Development of sustainable rea ction syst ems for the
palladiu m-catalyzed meth oxy- and hydro xycarbonylation of
alkenes: B oo n an d bane of multiphase system s

vorgelegt von
M.Sc.
Marcel Schmidt
aus Weißenfels

Falkult ä t II - Mathematik und Naturwissenschaften
der Technischen Universität Berlin
zur Erlangun g des akademischen G rades

Doktor der Ingenieurwissenschaften
- Dr.-Ing. -

genehmigte Dissertation

Promotionsausschuss:
Vorsitzender: Prof. Dr. Thomas Friedrich, TU Berlin
Gutachter: Prof. Dr. Reinhard S c homäcker, TU Berlin
Gutachter: Prof. Dr. Dieter Vogt, TU D ortm und

Tag der wissenschaftlichen Aussprache: 28.05.2019

Berlin 2019

Eidesstattliche Erklärung
I

Eidesstattlich e Erklärung
Hiermit erkläre ich an Eidesstatt, dass ich die vorl iegende Arbeit "Development
of sustainable reaction systems for the palladium-catalyzed methoxy- and
hydroxycarbonylation of alkenes: Boon and bane of multi phase systems"
selbstständig und eige nhändig sowie ohne unerlaubte Hilf e und ausschließlich
unter Verwendung der aufgeführten Qu elle n und Hilfsmittel angefertigt habe.
Die Darstellung meiner Eigenanteile in den aufgeführten Publikationen ist
zutreffend.

Ort, Datum Marcel Schmidt

Erklärun g z ur Dissertation
III

Erklärung zur Dissertati on
Ich erkläre hiermit, dass ich bisher an keiner anderen Hochschule oder Fakultät
meine Promotionsabsicht beantragt habe.
Die vorliegende kumulative Dissertation wurde bereits in Form von
wissensc haftl ichen Publikationen veröffentlicht. Es han delt sich hierbei um
folgend e Publikationen, die anhand d es Publikationsdatums c hronologisch
aufgelistet sind. Für alle in dieser Arbeit vorkommenden Publikationen liegen
die entsprechend en Genehmigungen d er Verlage (Reprint permissions) zur
Zweitpublikation vor.

PAPER 1: Superior catalyst recycling in surfactant based multiphase systems
- Quo vadis catalyst complex?
Tobias Pogrzeba, David Müller, Markus Illner, Marcel Schmidt , Yasemin
Kasaka, Ariane Weber, Günter Wozny, Reinhard Schomäcker, Michael
Schwarze
Chemical Engineering and Proc essing: Process Intensification, 2016, 99, 155-166
Eigenanteil: Vierter Autor. De r Ei nfluss vers chiedener Parame ter wie
Temperatur, Hydrophobi zität des Tensids etc . auf die Verteilung eines
homogenen Katalysatorkomplexes in Mikroem ulsionssystemen wurde gezeigt.
Weiterhin wurden diese Information en verwendet um einen En twurf für ein
entsprechendes Trennverfahren im industri ellen Maßstab zu erarbeiten. Das
gesamte Publi kationsteam hat die Konze ption des Forschungsansatzes u nd die
Versuchsplanung diskutiert. Ich habe mit Unterstützun g der stud entischen
Hilfskraft Ariane Weber die experime ntellen Untersuchungen zur
Katalysatorverteilung u nd deren Auswertung u nd Interpretation ü bernommen.
Außerdem wurde d er e ntsprechende Teil im Man uskript von mir verfasst. David
Müll er und Markus Illner, die wisse nschaftliche Mi tarbeiter in der Arbeitsgruppe
von Prof. Repke sind, h aben mit Unterstützung des üb rigen Publikationsteams
ein entsprechendes Prozesskonzept für Reaktionen im Mikroemulsionssystem
entworfen und verfasst.

Erklärun g z ur Dissertation
IV

PAPER 2: Verteilungsgleichgewichte von Liganden in mizellaren
Lösungsmittelsystemen
Marcel Schmidt , Tobias Pogrzeba, Dmitrij Stehl, René S ac hse, Mi chael
Schwarze, Regine von Klitzin g , Reinhard Schomäcker
Chemie Ingenieur Technik, 2016, 88, 119-127
Eigenanteil: Erstautor. Mizellare Medien als Reaktionssystem für die homogene
Katalyse sind eine vielversprechende Alternative zu konventionellen
Lösungsmittelsystemen. Dieser Beitrag untersucht die Verteilung von Liganden
bzw. des Katalysatorkomplexes in wässrig-mizellaren Medien und in einzelnen
Phasen eines tensid-basierten Mehrphasensystems. Die Konzeption des
Forschungsansatzes stammt von Michael Schwarze. Ich war
hauptverantwortlich für die Datenan alyse und -in terpretation u nd das Schreiben
des Manu skri ptes. Die Datenerhebu ng war Teil der Bachelorarbeit von René
Sachse. Ergänzende U ntersuchungen wurde von mir zur Vervollständ igung der
Daten durchgeführt. Der wissenschaftl iche Mitarbeiter Tobias Pogrzeba
unterstützte bei der Interpretation der Daten. Die Oberflächenspannun g wurde
von Dmitrij Stehl (wissenschaftlicher Mi tar beiter der Arbeitsgrup pe von Prof.
von Klitzing) gemesse n .

PAPER 3: Hydroformylation in microemulsions: Proof of concept in a minip lant
Markus Ill ner and David Müller, Erik Esche, Tobias Pogrzeba, Mar cel Schmid t ,
Reinhard Schomäcker, Günter Wozny, Jens-Uwe Repke
Indu stria l & Engineering Chemistry Rese arch, 2016, 55, 8616-8626
Eigenanteil: Vierter Autor. Die L a borergebnisse der Hyd ro formylierun g von
1-Dodecen wurden in einer kon tinuierlich-betriebenen Miniplant verifiziert. In
diesem Beitrag wurde der Aufbau und Betrieb dieser An lage, sow ie die
entsprechenden Ergebnisse , insbesondere zur Phasentrennung in dem speziell
dafü r entwickelten Dekanter, erläut ert. Ich lieferte einen erheblichen Beitrag bei
der Versuchsplanung, An al ytik und durchgehend en Betrieb
(200 Betriebsstunden) der Mi niplant. Hauptverantwortlich für den Betrieb der
Anlage waren Markus Ill ner, David Mü ller u nd Erik Esche, welche allesamt
wissensc haftl iche Mitarbeiter der Arbeitsgrupp e von Prof. Repke sind.

Erklärun g z ur Dissertation
V

PAPER 4: Catalytic reactions in aqueous surfactant-free multiph ase e mulsions
Tobias Pogrze ba, Marcel Schmidt , Lena Hohl, Ariane Weber, Georg Bu chner,
Joschka Schulz, Michael Schwarze, Matthias Kraume, Reinh ar d Schomäcker
Indu stria l & Engineering Chemistry Rese arch, 2016, 55, 12765-12775
Eigenanteil: Zweiter Autor. Am Beispiel der Hyd roformylierung von 1-Dodecen
und der Suzuki Kupplu ng wurde ein tensidfreies Reaktion ssystem mit einem
kurzkettigen Amphiphil als Lösungsvermittler vor ges tellt. Hau ptaugenmerk lag
hierbei auf der Möglich keit durch entsprechen de Wahl der Versuchsbedin g ungen
den Kataly satorkom plex quantitativ zu recyceln. Die Datenerhebun g erfolgte
größtenteils im Rah men der Bachelorarbeit von Ariane Weber
(Hydroformylierun g ) und der Masterarbeit von Georg Buchner (Suzuki
Kupplung). Ich habe Tobias Pogrzeba bei der Ve rsuchsplanung,
Dateninterpretation und bei ergänzenden Untersuchungen unterstützt. L ena
Hohl (wissenschaftl iche Mitarb eiterin der Arbeitsgrupp e von Prof. Kraume) und
der Stud en t Joschka Schulz haben die Phasenvolumina bestimmt.

PAPER 5: Microemulsion systems as switchable reaction media for the catalytic
upgrading of long-chain alkenes
Tobias Pogrzeba, Marku s Illn er, Marcel S chmidt , Jens-Uwe Rep ke, Rein har d
Schomäcker
Chemie Ingenieur Technik, 2017, 89, 459 -463
Eigenanteil: Dritter Autor. In d iese r Arbeit wurde die Anwendbarkeit von
Mikroemulsion ss ystemen für die Hydroformylierung von 1-Dodec en gezeigt.
Dabei wurde insbesondere au f die Übertragun g der Laborergebnisse auf d en
kontinuierlichen Betrieb der Min iplant eingegangen. Ich habe den
wissensc haftl ichen Mitarbeiter Tobias Pogrzeba b ei der Versuchsplanung und
Dateninterpretation unterstützt. Weiterhin war ich aktiver Bestandteil d es
Teams beim Betrieb d er Min i plant, welcher von Mark us Ill ner
(wissenschaftlicher Mitarbeiter der Arbeitsgrupp e von Prof. Repke ) geleitet
wurde.

Erklärun g z ur Dissertation
VI

PAPER 6: Improving th e catalytic activity in th e rhodium -mediated
hydroformylati o n of styrene by a Bis(N-heterocyc lic silyene) ligand
Marcel Schmi dt , Bu rgert Blom, Tib or Szilvási, Rein hard Schomäcker, Matth ias
Driess
European Journal of Inorganic Chemistry, 2017, 9, 1284-1291
Eigenanteil: Erstautor. Zur Steigerung d er Aktiv i tät von homogen-katalysierten
Reaktionen spielen neuartige Liganden eine entscheiden de Rolle. In d iese r
Arbeit wurden neuartige N-heterozyklische Silyene als Liganden am Beispiel der
rhodium-katalysierten Hydroformyl ieru ng von Styrol untersucht. Reinhard
Schomäcker und Mat thias Driess li eferten d as Kon ze pt d er For schungsarbeit.
Ich hab e die Versuche mit Unters tützun g von Burgert Bl om (Post-doc d er
Arbeitsgrupp e von Prof. Driess) geplan t, durchgeführt und ausge wertet, wobei
Burgert Bl om vorwiegend d en analytischen Teil du rchgeführt hat. Tibor S zilvási
hat die DFT Berechnungen ausgeführt. Ich war f ür das Schreiben d es
Manu skri ptes zuständig.

PAPER 7: Palladium-catalyzed methoxycarbonylation of 1-dodecene in biphasic
systems - Optimization of catalyst recycling
Marcel Schmidt , Tobias Pogrzeba, L ena Hohl, Ariane Weber, André Ki elholz,
Matthias Kraume, Reinhard Schomäcker
Molecular Catalysis, 2017, 439, 1-8
Eigenanteil: Erstautor. In d ieser Veröff entlichung wurde die Verwendung eines
Zweiphasensystems hin sichtlich der qu a ntitativen Abtrennung des Kat alysators
für die Methoxycarbonylierung von 1-Dodecen demonstriert. Besonderes
Augenmerk lag auf dem Zusammenhan g zwischen Reakt ionsperformance u nd
Güte des Kataly satorr ecyclings. Ich war hauptverantwortlich für die Konzeption
des Forschu ngsansatzes, der Planun g der Untersuchun gen sowie für das
Schreiben des Man uskriptes. Ein Großteil der experimentellen Untersuchu nge n
wurden im Zuge der Bachelorarbeit von André Kielhol z durchgeführt, die von
mir b etre ut wurde. Ergänzende experimentelle Un ters uchun gen wurden von mir
durchgeführt. Tobias Pogrzeba (wissenschaf tlicher Mitarbeiter) und Ariane
Weber (stu dentische Hilfskraft) unterstützen b ei der Int erpretation der Daten.
Lena Ho hl (wisse nschaf tliche Mitarbeiterin der Arbeitsgruppe von Prof.
Kraume) führte die Untersuchun gen zur Grenzflächenspann ung und
Tröpfchengröße durch.

Erklärun g z ur Dissertation
VII

PAPER 8: Understanding th e role of nonionic surfactants during the catalysis in
microemulsion systems on the example of rhodiu m-catalyzed hydrofor mylation
Tobias Pogrzeba, Mar cel Schmidt , Natasa Miloj ev ic, Carolina Urban, Markus
Illner, Jens-Uwe Repke, Reinh ar d Schomäcker
Indu stria l & Engineering Chemistry Rese arch, 2017, 56, 9934-9941
Eigenanteil: Zweiter A utor. In dieser Arbeit wurd e der Einfluss n ichtionischer
Tenside auf die Hydroformylierun g von 1-Dodecen un tersucht. Durch
systematische Variati on der Temperatur, Tensidkonzentration und der
Hydrophobizität d es Tensids kon nte der Einfluss des Phasenverhaltens des
Mikroemulsion ss ystems au f d ie Reaktionsergebnisse diskuti ert werden. Die
Datenerhebung erfolgte größtenteils im Rahmen der Bachelorarbeit von Natasa
Miloj ev ic und Carolina Urban , d ie b ei de von Tobias Pogrzeba betreut wurd en.
Ergänzende experimentelle Untersuchungen wurden von Tobias Pogrzeba
durchgeführt. Ich h a be Tobi as Pogrzeba bei d er Versuchsplanun g u nd
Dateninterpretation unterstützt.

PAPER 9: Alkaline hydrolysis of methyl decanoate in surf actant based systems
Marcel Schmidt , Johannes Deckwerth, Reinh a rd Schomäcker, Michael Schwarze
The Journal of Organic Chemistry, 2018, 83, 14, 7398-7406
Eigenanteil: Erstautor. Die basische Verseifu ng von lan gkettigen Estern ist
durch die geringe L ösl ichkeit d es Substrates in wässrige n Med ien gehem mt. In
dieser Veröffentl ichung wurd en systematisch eine Reihe von ionischen und
nichtionischen Tenside n zur Modifizierung des Reakt ionssystems getestet u m die
basische Verseifun g von Methyldecanoat in wässrigen Medien zu ermöglichen.
Es stellte sich heraus, dass das resultierende Produkt der Verse ifun g, die
Decansäure, selbst grenzfläch enaktiv ist und somit autokatal ytisch die
Verseifung beschleunigt. Für die Kon zeption des Forschungsansatzes un d die
Versuchsplanung war ich verantwortlich. Ein Großteil d er veröffentlichten
Daten wurden von Johannes Deckwerth im Rah men seiner Bachelorarbeit
erbracht, die von mir betreut wurd e, wobei ergänzende Untersuchungen von mir
durchgeführt wurden. Für das Schreiben des Manuskriptes war ich ebenfalls
zuständig, wobei Michael Schwarze die Einleitun g diese r Veröf fentlichung
verfasst hat.

Erklärun g z ur Dissertation
VIII

PAPER 10: Palladium- catalyzed m ethoxycarbonylation of 1-dodecene in a
two-phase system: The path toward a c ontinuous process
Markus Illn er and Marcel Schmidt , Tobias Pogrzeba, Carolin a Urban , Erik
Esche, Reinhard Schomäcker, Jens-Uwe Repke
Indu stria l & Engineering Chemistry Rese arch, 2018, 57, 8884-8894
Eigenanteil: Geteilte Erstautor enschaft mit Markus Illner. In d ies em Beitrag
werden Lab orergebniss e und d ere n Üb ertragung in eine kontinuierlich-betriebene
Miniplant für die p alladium-katalysierte Methoxycarbonylierung präse ntiert. Die
Erreichung eines stabilen Betriebspunk tes, der sich d urch eine hohe Ausbeute
mit stabiler Phasentrennung a uszeichnet, wa r h ierbei der Schwerpunkt. Für d ie
Konzeption d es Forschu ngsansatzes un d d ie Versuchsplanung waren Marku s
Illner (wissenschaftlicher Mitarb eiter d er Arbeit sgruppe von Prof. Repke) und
ich zuständ ig. Die Labordaten wurden von mir mit Un terstützung von der
studenti sc hen Hilfskraft Carolin a Urban erhob en, wobei deren Interpretation
mit den gesamten Pub likationsteam d iskutiert wurd en. Weiterhin habe ich beim
Betrieb des Prozesses i n d er Miniplant maßgeblich mitgearbeitet und au ch diese
Ergebnisse vorwiegend mit Markus Illner ausgewerte t und interpretiert. Für d as
Schreiben d es Manuskriptes waren in gleichen An teilen Markus Illner und ich
verantwortlich.

PAPER 11: Pall adium- catalyzed h ydroxycarbonylation of 1-dodecene in
microemulsion systems: Does reaction performance care about phase behavior?
Marcel Schmidt , Carolina Urban, Svenja Schmidt, Reinhard Schomäcker
ACS Omega, 2018, 3, 13355-13364
Eigenanteil: Erstautor. In diesem B eitrag wu rde die Hyd rocarbox ylierun g von
1-Dodecen im Mi kroemulsionssystem u ntersucht. S c hwerpunkt lag auf d e r
Erörterung des Zusammenhangs zwischen Phasenverhalten und
Reaktionsleistung u m die Rol le des Tensids zu verdeutlichen. Ich war fü r den
methodischen Schwerpunkt des Forschu ngsa nsatzes, die detaillierte
Versuchsplanung, d ie Datenauswertung und -interpretation sowie das S chreiben
des Manuskriptes zuständig. Ein Teil der Daten (ca. 30%) w urden von Svenja
Schmidt im Rahmen ihrer Bachelorarbeit erhoben, die von mir betreut wurde.
Ein Großteil der experimentellen Un tersuchungen wurden von mir mit
Unterstützung von Carolina Urban (stud en tische Hilfskraft) durchgeführt.

Erklärun g z ur Dissertation
IX

Im Anhang d iese r Dissertation sind die jeweiligen Exemplare der hier
aufgeführten Publikationen beigefü gt.

Ort, Datum Marcel Schmidt

Abstract
XI

Abstract
Catalysis plays a major role in chemistry. In particular, homogeneo us catal ysis
opens the door to a sustainable sy nthe sis of many products, offering mil d reaction
conditions, excellent ac tivity as well as selectivity. How ever, the recycling of the
expensive catalyst complexes is a major draw back, hampe ring the implementation
of homogeneous catalysis for industrial application. Hence, alt ernative approac he s
for the re cycling of homogeneous catalysts in its acti ve form are in the focus of
current researc h , combining the advantages of both, homogeneous and
heterogeneous catalysis. In this thesis, the applicability of multiphase systems fo r
the pall adium- catalyzed methoxy - and hydroxycarbonylation of different substrates
is investigated, enab ling a consecutive catalyst recycling and product separation via
temperature-induced phase separation. Special attention is given to the selec t ion of
the solvents/additives to ensure catalyst stability, quantitative cataly st recycling,
product separation and overall good reaction performance. The immobilization of
the palladium-based catalyst in the polar phase is guaranteed by the use of the
watersoluble ligand SulfoXantP hos and methane sulfonic acid as co‐catalyst in a
ratio of 1:4:40, facilitat ing the long term cata lyst stability.
For th e methoxycarbonylation of 1-dodecene in multiphase systems, the path
toward a continuous process is reported, inc lud ing solvent selection, parameter
studies and the proof of conce pt in a miniplant. A si mple biphasic system can be
used composed of water/methano l as polar phase and octane/1-dodecene as
nonpolar phase, leading to a good reaction performance and fast phase separation
at room temperature (Pd le aching < 1 ppm). Parameter studies reveal catalyst
stability up to 80 °C, achie ving a yield of 92% to the corresponding ester after a
reaction time of 20 h. Mor eover, the transf er of the lab scale results into a
continuously operated mini plant (reaction volume scale up factor: 19) is shown,
operating continuously ove r 100 h with stable phase separation (Pd le aching <
25 ppb) and under steady state conditions (yiel d to the ester = 83.5%).
In contrast, the palladium-catalyz ed hydroxycarbonylation of 1-dodecene is not
feasible in a si mp le bip hasic sy st em w ithout additives, since the solubility of the
substrate is too low in the catalyst phase. Herei n, the complex role of surfactants as
additives and the inter a ction between the phase behavi o r and re action performanc e
is in vestigated. The investigations reveal that not the ph ase beh avior of the
microemulsion system but mainly the size of the oil –wate r interface and the local
concentrations at this inte rface control the reaction performa nce of the
hydroxycarbonylation i n these systems.

Zusammenfassung
XIII

Zusammenfas sung
Katalyse spielt in der Chemie ei n e große Rolle. Insbesondere d ie homo gene Katalyse
ebnet den We g zu einer nachhaltigen Synt hese vieler Produkte, da mil d e
Reaktionsbedingungen, her vorragende Aktivi täten sowie Selektivitä ten re alisiert
werden können. Jedoch is t das Recycling des mei st teuren Katalysatorkomplexes
ein entscheidender Nachteil, der die industrielle Umsetzung der homogenen
Katalyse erschwert. D aher stehen a lternative Ansätze für das Rec ycling von
homogenen Katalysatoren im Fokus der aktuell en Forschung. In dieser Arbe it wird
die Anwendbarkeit von Mehrphasensystemen für die Pall adiu m-katalysierte
Methoxy- und Hydroxycarbonylierung verschiedener Substrate untersucht, was eine
anschließende Katalysatorrückfü hrung und Produktabtrennung durch
Phasentrennung ermöglicht. Bes onde res Augen merk wird dabei auf die Auswahl der
Lösungsmittel/Additive gelegt, um Katalysatorstabilität, quantitatives
Katalysatorrecycling, Produktabtrennung und ei ne gute Reaktion sleistung zu
gewährleisten. Die Immobilisierung des Palladium-basierten Katalysators in der
polaren Phase wird durch die V erwendung des wasserlöslich en Liganden
SulfoXantPhos ermöglicht. Um die Lang zeitstabilität des Katalysators zu
gewährleisten, wird Methansulfonsäure als Kokatalysator eingesetzt, wobei ein
Pd:Ligand:Kokatalysato r Verhältnis von 1:4:40 verw endet wird.
Für die Methoxycarbonyli erung von 1-Dodecen im Mehrphasensystem wird der
Weg vom Labor zu einem kontinuierl ichen Proz ess im P ilotanlagenmaßstab
beschrieben, einschließlich Lösungsmitte lauswah l, Parameterstudien und
Konzeptnachweis in der Pilotanlage. Es kann ein einfaches Zwe iphasensystem
verwendet werden, welches aus Wasser/Meth anol als polare Phase und Ok tan/1-
Dodecen als unpolare Phase besteht, was zu einer guten Re a ktionsleistung und
schnellen Phasentrennun g bei Raumtemperatur führt (Pd-Verlust < 1 ppm). Die
Parameterstudien zeigen, dass die Katalysators tabilität bis 80 °C gege b en ist, wobei
eine Ausbeute zum entspre ch enden Ester von 92% nach 20 h Reakti o nszeit erzielt
wird. Darüber hinaus wird die Übertragu ng der Laborergebnisse in eine
kontinuierlich-betrieben e Pilotanlage (Reaktionsvolumen-Skalierungsfaktor: 19)
gezeigt, welche über 100 Stunden kontinuie rlich mit stabiler Phasentr ennung (Pd-
Verlust < 25 ppb) und unter stationä ren Bedingungen (Ausbeute des Esters =
83,5%) betrieben wurde.
Im Gegensatz dazu is t die Palladium-kata lysierte Hydroxycarbony lierung von
1-Dodecen in einem einfachen Zweiphasensystem ohne Additive nic ht möglich, da
die Löslichkeit des Substrats in der Katalysatorphase zu gering ist. Hie rbei wird die
komplexe Rolle von Tensiden als Additiv und die Wechselwirkung zwischen
Phasenverhalten und Re aktionsverha lten untersucht. Die Untersuch ungen zeige n ,
dass nic ht das Phasenverhalten des Mikroemulsionssystems, sondern hauptsächlich
die Größe der Öl -W asser-Grenzfläche und die lokalen Konzentrationen de r
Substrate und des Katalysatorkomplex es an dieser Grenzfläche die
Reaktionsleistung der H ydroxycarbonylierung st euern.

List of Publications
XV

List of Publicati ons
Contributing publi catio ns
Here, all publication s are li sted in chronological order which contribu te to this
cumulative th es is.
PAPER 1: Superior catalyst recycling in surfactant based multiphase systems
- Quo vadis catalyst complex?
T. Pogrzeba, D. Müll er, M. Illn er, M. Schmidt , Y. Kasaka, A. Weber, G.
Wozny, R. S c homäcker, M. Schwarze:
Chem. Eng. Process.
, 2016 , 99, 155-166.
DOI: 10.1016/j.cep.2015.09.003
PAPER 2: Verteilungsgleichgewichte von L iganden in mizellaren Lösungsmittel-
systeme n
M. Schmidt , T. Pogrzeba, D. S tehl, R . S achs e, M . S chwarze , R. von Kl itzing ,
R. Schomäcker: Chem. Ing. Tech., 2016 , 88, 119-127.
DOI: 10.1002/cite.201500125
PAPER 3: Hydroformylation in microemulsions: Proof of concept in a minip lant
M. Illner and D. Müller, E. Esche, T. Pogrzeb a, M. S chmidt , R. S chomäcker,
G. Wozny, J.-U. Repke: Ind. Eng. Chem. Res ., 2016 , 55, 8616-8626.
DOI: 10.1021/acs.iecr.6b00547
PAPER 4: Catalytic reactions in aqueous surfactant-free multiph ase e mulsions
T. Pogrzeba, M. Schmidt , L . Hohl, A. Weber, G. Buchn er, J. Schu lz, M.
Schwarze, M. Krau me , R. Schomäc ker: Ind . Eng. Chem. Res., 2016 , 55,
12765-12775.
DOI: 10.1021/acs.iecr.6b03384
PAPER 5: Microemulsion systems as switchable reaction media for the catalytic
upgrading of long-chain alkenes
T. Pogrzeba, M. Illner, M. Schmidt , J.-U. Rep ke, R. S chomäcker: Chem. Ing.
Tech., 2017 , 89, 459-463.
DOI: 10.1002/cite.201600140

List of Publications
XVI

PAPER 6: Improvin g the catalyt ic activi ty in th e rhodium-mediated hydro-
formylation of styrene by a Bis(N-heterocyclic silyene) ligand
M. Schmidt , B. Blom, T. S zil vási, R. Schomäcker, M. Driess: Eur. J. Inorg.
Chem., 2017 , 9, 1284-1291.
DOI: 10.1002/ejic.201700148
PAPER 7: Palladium-catalyzed methoxycarbonylation of 1-dodecene in biphasic
systems - Optimization of catalyst recycling
M. S chmidt , T. Pogrzeba, L. Hohl, A. Weber, A. Kielholz, M. Kraume, R.
Schomäcker: Mol. Catal., 2017 , 439, 1-8.
DOI: 10.1016/j.mcat.2017.06.014
PAPER 8: Understanding th e role of nonionic surfactants during the catalysis in
microemulsion systems on the example of rhodiu m-catalyzed hydrofor mylation
T. Pogrze ba, M. Schm idt , N. Milojevic, C. Urban, M. Illner, J.-U. Repke, R .
Schomäcker: Ind. Eng. Chem. Res., 2017 , 56, 9934-9941.
DOI: 10.1021/acs.iecr.7b02242
PAPER 9: Alkaline hydrolysis of methyl decanoate in surf actant based systems
M. S chmi dt , J. Deckwerth, R. S chomäcker, M. Schwarze: J. Org. Chem.,
2018 , 83, 14, 7398-7406.
DOI: 10.1021/acs.joc.8b00247
PAPER 10: Palladium- catalyzed me thoxycarbon ylation of 1-dodecene in a two-
phase system: The path toward a continuous process
M. Ill ner and M. S chmidt , T. Pogrzeba, C. Urban, E. Esche, R . Schomäcker,
J.-U. Repke: Ind. Eng. Chem. Res., 2018 , 57, 8884-8894.
DOI: 10.1021/acs.iecr.8b01537
PAPER 11: Pall a dium-catalyzed hydroxycarbonylation of 1-dod ecene in micro-
emulsion systems: Does reaction performance care about ph ase behavior?
M. Schmid t , C. Urban, S . Schmidt, R. S chomäc ker: ACS Omega, 2018 , 3,
13355-13364.
DOI: 10.1021/acsomega.8b01708

List of Publications
XVII

Non-contributing p ubli cations
In th e following, all publications are li sted which were published d uring the time
as scientific assistant at the chair of technical chemistry, TU Berlin, but d o not
contribute to this thesis.
PAPER 12: A novel process concept for the three step Boscalid ® synth esis
I. Volov ych, M. Neumann, M. S chmidt , G. Bu chner, J.-Y. Yang, J. Wölk, T.
Sottmann, R. S trey, R. Schomäcker, M. Schwarze: RS C Adv., 2016 , 6, 58279-
58287.
DOI: 10.1039/C6RA10484C
PAPER 13: Characteristics of stable p ickering emulsion s under p roce ss
conditions
D. S tehl, L. Hohl, M. Schmidt , J. Hübner, M. Lehmann, M. Kraume, R.
Schomäcker, R. von Klitzing: Chem. Ing. Tech., 2016 , 88, 1806-1814.
DOI: 10.1002/cite.201600065
PAPER 14: Hyd rogenation of itaconic acid in micellar solut ions: Catalyst
recycling with cloud point extraction ?
M. Schmidt , S . Schreiber, L . Franz, H. L anghoff, A. Farhang, M. Horstmann,
H.-J. Drexler, D. Heller, M. S chwarze : Ind. E ng. Chem. Res., 2019 , 58, 2445-
2453.
DOI: 10.1021/acs.iecr.8b03313

Table of Contents
XIX

Table of C ontents
Eidesstattliche Erklärung ......... ......... ............ ........... ............ ......... ........... ........... I
Erklärung zur Dissertation ......... ......... ............ ........... ............ ......... ........... ...... III
Abstract ... ......... ............ ........... ......... ............ ........... ............ ......... ........... ........ XI
Zusammenfassung ......... ......... ............ ........... ............ ......... ........... ............ ..... XIII
List of Publications...... ............ ......... ........... ............ ......... ........... ............ ........ XV
Contributing publications ... ............ ......... ........... ............ ......... ........... ......... XV
Non-contributing publications ......... ......... ............ ........... ......... ............ .....XVII
Table of Contents ......... ......... ............ ........... ......... ............ ........... ............ ...... XIX
Symbols and Abbreviations ......... ......... ............ ........... ............ ......... ........... ... XXI
List of Figures ......... ............ ........... ............ ......... ........... ............ ......... ........ XXIII
List of Tables ......... ......... ............ ........... ............ ......... ........... ............ ........... XXV
1. Introduction ...... ......... ............ ........... ......... ............ ........... ............ ......... ....... 1
1.1 Motiv at ion ......... ............ ......... ........... ............ ......... ........... ............ ......... 1
1.2 Outline of this Work ... ............ ......... ........... ............ ......... ........... ........... 2
2. Theoreti ca l Background ... ......... ............ ........... ............ ......... ........... ............ . 4
2.1 Reppe Carbonylation ......... ............ ......... ........... ............ ......... ........... ..... 4
2.1.1 "Carboxy" vs. "Hyd ri de" Mec hanism ... ............ ......... ........... ............ .. 5
2.1.2 Mechanism of Methoxycarbonyl ation ... ............ ............ ........... ......... ... 6
2.1.3 Deactivation pathways of homogeneous pall a dium catalysts ......... ..... 8
2.1.4 Kin etic studies ...... ......... ............ ........... ......... ............ ........... ............ .. 9
2.1.5 Indu stria l application ......... ......... ............ ........... ......... ............ .......... 11
2.2 Green Chemistry ......... ......... ............ ........... ............ ......... ........... ......... 12
2.3 Multiphase Systems ...... ............ ......... ........... ............ ......... ........... ........ 13
2.3.1 Aqueous biphasic systems ... ............ ......... ........... ............ ......... ......... 15
2.3.2 Surfactant-b ase d multiphase systems ......... ......... ............ ........... ....... 16
2.3.3 Miscellaneous multi ph ase systems ...... ......... ............ ........... ............ ... 18
3. Experimental Part ......... ......... ............ ........... ............ ......... ........... ............ . 21
3.1 Chemicals ...... ............ ............ ........ ............ ............ ........... ......... ........... 21

Table of Contents
XX

3.2 Determination of CMC ...... ......... ............ ........... ......... ............ ........... .. 21
3.3 Investigation o n the phase behavior ...... ......... ............ ........... ............ .. 21
3.4 Preformation of th e Catalyst for Carbonylation Reactions ......... ......... 22
3.5 Setup for Carbo nylation Reactions ... ............ ......... ........... ............ ....... 22
3.6 Experimental Procedure for Carbonylation Reactions ... ............ .......... 23
3.7 Determination of Catalyst Leaching and Pro duct Distribution ......... .. 24
3.8 General procedure of the Alkali ne Hy drolysis ......... ............ ......... ........ 24
4. Results and Discussion ............ ......... ........... ............ ......... ........... ............ ... 26
4.1 Green Chemistry and InPROMPT ... ............ ............ ........... ......... ....... 26
4.1.1 Statu s Quo - Hydro formylation in Microemulsion Systems ......... ..... 27
4.1.2 Sil y lene Ligands as Alternatives ... ............ ......... ........... ............ ........ 28
4.2 Methoxy carbo nylation in Microemulsion Systems ...... ............ ............ . 30
4.2.1 Impact of Methan ol on the Phase Behavior ......... ............ ......... ....... 31
4.2.2 Impact of Methan ol on the Reaction Performance ......... ......... ......... 32
4.3 Methoxy carbo nylation in Biphasic Systems ... ............ ............ ........... ... 33
4.3.1 Solv ent Selection ...... ......... ............ ........... ............ ......... ........... ........ 34
4.3.2 Parameter studies ............ ......... ........... ............ ......... ........... ............ . 38
4.3.3 Proof of concept in a miniplan t ............ ............ ........ ............ ............ 40
4.4 Hydroxy carbo nylation in Microemulsion Systems ............ ............ ........ 42
4.4.1 Catalyst Behavi or in Microemulsion Systems ......... ......... ............ ..... 42
4.4.2 Nonionic Surfactants as Phase Transfer Agent... ............ ......... ......... 44
4.4.3 Ionic Su rfacta nts as Phase Transfer Agent ......... ............ ......... ......... 47
4.5 Alkaline Hydroly sis of long chain esters ...... ............ ......... ........... ......... 50
4.5.1 Alkaline Hydroly sis in Water ... ............ ............ ........ ............ ............ 50
4.5.2 Alkaline Hydroly sis in Surfactant-Based Systems ... ............ ......... ..... 51
5. Conclusion ............ ......... ........... ............ ............ ........ ............ ............ .......... 54
References ... ............ ............ ........... ......... ............ ........... ............ ......... ........... .. 56
Acknowledgement ... ......... ............ ........... ............ ......... ........... ............ ............ .. 63
Appendix ... ............ ............ ........... ......... ............ ........... ......... ............ ........... .... 64

Symbols and Abbreviation s
XXI

Symbols and Abbrevia tions
Table I. Lis t of abbreviations.
Abbreviation Description
CMC Critical micelle co ncentra tion
CTAB Hexadecyltrim ethylamm onium bromide
DecMIM 1-Methyl -3-decylimi dazolium bromide
DeTAB Decyltrime thylammoni um bromide
DFT Density func tional theor y
DodecMIM 1-Methyl -3-dodecylimi dazolium bromide
DTAB Dodecyltrime thlyammoni um bromide
d t bpx 1,2-bis(di-
tert
-butyl phosphi nomethyl )benzene
FID Flame ioniza tion detecto r
ICP-OES Inductively coupled plasma o ptical emissi on spec trometry
MMA Methyl metha crylate
MSA Methane sulfonic a cid
NHSi N-heterocyclic si lyene
NMR Nuclear magn etic resona nce
p
-TSA
para
-Toluen esulfonic aci d
OMIM 1-Methyl -3-octylimidazoli um bromide
RDS Rate-determini ng step
scCO
2

Supercritical carbon diox ide
SDS Sodium dodecyl sulfate
SX SulfoXant Phos
TFA Trifluoracetic acid
TMS Thermomorphic multico mponent syst em
TOF Turn over frequency
TPP Triphenylp hosphine
TPPTS 3,3',3''-Phosphanetriy ltris(benze nesulfonic a cid) tr isodium salt
TTAB Tetradecyl trimethylamm onium bromide

List of Figures
XXIII

List of Figures
Figure 1. Ou tline of this work. .... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... .... 2
Figure 2. Repp e Carbony lation of alkenes with diff erent nucleo philes . .. .... ...... .... ...... ..... 4
Figure 3. Propos ed "hydride" and "carboxy" mechani sm for the methoxycarbonylati on
of ethene. .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... .... . 5
Figure 4. Propos ed "hydrid e" mechanism for the me th oxycarbonyl ation of an olefin
(green background) inclu ding the formation of activ e palladium-hydride species (yellow
background ) and possible cataly st deactiv ation p athways (red backgroun d), L = CO,
MeOH, solvent, coordinating anion of the acid or anion of pall adium pr ecursor, li gand. 7
Figure 5. The Twelve Principl es of Green Che mistry. .. ...... .... ...... ...... .... ...... .... ...... ..... 12
Figure 6. Gibbs phase pr ism for a microemulsi on sy stem consi sting of oil, water and a
nonionic surfac tant (left pi cture), cut of the phase prism at α=0 .5 (right pi cture).. .. ... 17
Figure 7. Experim ental s etup for methox y- and h ydroxy carbonylation rea ction. .. .... ... 22
Figure 8. Sche matic process concept for the hydroformyl ation of long-chain alkenes in
microemulsi on systems. .... ...... .... ...... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... .... 26
Figure 9. Mini plant oper ation results for the hydr oformylation of 1-dode cene. .... .... .... 28
Figure 10. Sche matic comparison bet ween the hydrofo rmylation and
methoxycarbonyl ation re action. .... .... ...... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... .... ...... . 30
Figure 11. Phase boundaries for the microe mulsion system consisting of water, 1-
dodecene and Marli pal 2 4/70 with different amou nts of MeOH. .. .... ...... .... ...... ...... .... .. 31
Figure 12. Yiel d of tridecanoic acid, dodecane and methyl tridec anoate f or the
methoxycarbonyl ation in microemulsi on systems. .. .... ...... .... ...... ...... .... ...... .... ...... .... .... 33
Figure 13. Rea ction mixture after phase separation at room temperature (separation
time of 10 min). ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... .... ...... .... ...... ... 36
Figure 14. Mini -plant op eration results fo r the me thoxycarbonyl ation of 1 -dodecene. .. 41
Figure 15. Sche matic pic tures of the oil-in-water microemulsi on, triphasic system and
water-in-oil microemulsion for the palladium-cataly zed hydroxycarb onylati on of
1-dodecene. ...... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... 44
Figure 16. Phase diagram of a mixture of 1-dodecene, dodecane, water, and Marlipal
(24/50). .. ...... .... ...... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ... 45
Figure 17. Effe ct of the surfactant concentrati on on the hydr oxycar bonylation of
1-dodecene. .. ...... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .. 46
Figure 18. Rea ction sequence for the synthesi s of carboxyli c acids fro m olefins. .... ...... 50
Figure 19. Effe ct of the temperature on the conv ersi on plot of th e alkali ne hydrol ysis of
methyl decano ate in wat er. .. ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... 51

List of Tables
XXV

List of Table s
Table 1. Conversi on, l:b ratio and T OF of the hydrofor mylation wi th
[HRh(CO)(P Ph 3 )L 2 ] complexes containing bidentate ligands L 2 at different
temperatures . .... ...... .... ...... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... ... 29
T a b l e 2 . Methoxy carbonyl ation of 1-dodecene: M odifi cation of the polar p hase. .. ...... . 35
T a b l e 3 . Methoxy carbonyl ation in biphasi c systems: Substr ate scop e. ...... ...... .... ...... .. 37
T a b l e 4 . Methoxy carbonyl ation of 1-dodecene: Va riation of the temperatur e. .... ...... ... 39
T a b l e 5 . Hydroxy carbonylati on of 1-dodec ene: Ioni c surfactants as phase transfer
agents. .... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... ... 47
T a b l e 6 . Hydroxycarbo n ylation of 1 -dodecene: Ioni c liquid s as phase trans fer agents . . 48
T a b l e 7 . Hydroxycarbo n ylation of 1 -dodecene: Va riation of OMIM conc entration. .... . 49
T a b l e 8 . CMC values and initial reaction rates for the alkali ne hydrolys is in surfactant-
based systems. .. ...... ...... .... ...... .... ...... ...... .... ...... .... ...... .... ...... ...... .... ...... .... ...... ...... .... ... 52

Introdu ct ion
1

1. Introduction
1.1 Motivation
The world changes. Futuristic cars cre ep without a sound along the street, wind
parks emboss th e n atural scenery, biobased f oodstuffs capture the racks in
supermarkets, p hotovoltaic systems cove r the roofs of many houses, dif ferent
colored waste contain er await s you in th e backyard of buildings, green labels
mark the packin g of consumer produ cts and many more. All th es e f acts can be
connected to the term sustainability. Circ umstances h ave changed and as a
result, the thinking of hu mans changed. 200 years ago, the term sustainability
had no relevance in society b ec ause human action is subliminally based on
sustainability. With the beginning of the Industrial Revolution at the end of the
18th century, the structural c hange from agricul ture to industry is strongly
associated with a h uge growth of population an d t he increase in living stand ar d.
Thus, fossil resources h ave been made accessible to meet th e n eeds of the
growing society li ke energy demand and th e craving for new p roducts. However,
the consumption of f o ssil resources is limited, which was not considered for a
long time. Nowaday s, the global annual o il p r oduction is st ill increasing bu t it is
a question of ti me that th e oil peak will come in near future and new solutions
have to be establi shed. Not on ly in this field b ut also in a lot of different areas
like tran sportatio n, living, food, materials and many more, th e gl obal society
faces new challenges b ec ause of the chan ged way of life. In all th es e areas, th e
term sustain ability is on ever yone´s li ps. A major role can be attributed to the
natural and engineering sciences to meet the new requi rem ents. Especially in
chemistry, the way of th inking has chan ged. Formerly, the produ ct itself with a
certain functionality and its synthesis as m uch cheap as possible was in th e
focus. Nowaday s, th e term sustainabil ity hovers ab ove all . This mean s th at not
only economical but also ecological and social aspects have to b e considered.
Pioneering work was done by Paul Anastas and John Warner who established a
guideline for a green and sustainable chemistry, opening out in to the Twelve
Principl es of Green Chem istry. 1
In this doctoral thesis, chemistry an d engineering have been done, following th e
requirements of Gre en Chemistry. For su re, in the context of all global
challenges, this work is only a drop in the bucket but it is a step in the right
direction, gaining vi sibility a nd sensitizi ng the society f or th e fu ture challenges.
Herein, alternati ve reaction media f or organic transformations, especially for the
palladiu m- catalyzed methoxy- and hydroxycarbonyl ation reaction, have been
investigated in th e context of Green Chemistry, avoidin g toxic solvents and
using aqueous multiphase systems as the desired rea ction medium. This

Introdu ct ion
2

approach facilitates the recycling of the exp e nsive catalyst in it s active form an d
the se paration of the p roduct f rom the re action mixture v ia simple phase
separation. Moreover, the applicability of m ultiphase systems with subsequent
catalyst recycling has b een studied in a continu ously operate d miniplant. This
methodology represen ts a green and sustainable approach for organi c
transformations on large s cale with respect to economic, ecological, and even
human demand.
1.2 Outline of this Wo rk
This doctoral th es is is a cumul ative work, based on eleven p ee r-reviewed papers
in different international j ourna ls. Additional to the data f rom th e p apers,
unpublished results are presented to illustrate the to pical context of the
published results. Mainly, this work is divided in to three topics, which are
depicted in Figure 1.

Figure 1. Outline of this wo rk.
First, the status quo for th e hyd ro formylation of 1-dodec ene in microemulsion
systems is presented, which was main ly a result of th e d octoral thesis of former
members from our group . 2,3 Addit ionally, new ligan ds f or the hydroformyl ation

Introdu ct ion
3

reaction th at are based on sili con were tested, giving a signifi cant boost in the
catalytic activity. Second, the methoxycarb onylation o f different alk enes in
biphasic systems is investigated, including solvent selection, parameter studies,
and the proof of concept in a continuously operated miniplant. Moreover, the
methoxycarbonylation of 1-dodecene in mi croemulsion systems i s p resented,
investigating the phase behavior and the reac tion performance. Third, t he
hydroxycarbonylation of 1-dod ecene in surfactant-based systems is stud ied,
containing the catalyst behavi or in microemu lsion systems, the p has e behavi or
of these systems, and parameter studies such as surfactant concentration .

Theoretical Background
4

2. Theoretical B ackground
2.1 Reppe Carbonyla tion 4–6
Since the d iscovery in th e 1930s, the Rep pe carbonylati o n is on e of the most
important reactions functionalizing low-value feedstocks. 7–12 Ini tially, Walter
Reppe reported th e successful transformation of ethylene with carbon monox ide
and water to acrylic acid, using nickel as catalyst. The principles of this reaction
can b e easily extended to a broad range of substrates, particularly alkenes and
alkyn es , which offers access to a wide spectrum of bulk and fine chemicals as
well as intermediates for organi c synthesis. Furth ermore , a lot of different
fun ct ional groups are tolerated du ring the reaction sequence, in creasing the
spectrum of possible products and thus, the attention of chemists.
In general, the Reppe carbon ylation is a very atom economic transformation
combinin g three different reactants: an unsaturated carbon cha in, a source for
the carbonyl unit and a n ucleophile. Herein, the carbonylati on of alk enes is in
the f ocus (see Figu re 2), but alkynes and conjugated dienes, especially
butadiene 13 , can be used as well. Mostly, pure carbon monoxide is u se d as the
carbonyl source. However, d ue to th e dif ficult handling of gas eous carbon
monoxide a nd its to xic properties, a lternative carbonyl sources h as been
investigated like formic acid and its derivatives, metal carbon yl complexes or
even aldehyd es . 14

Figure 2. Reppe Carbonylat ion of alkene s with different nucleophiles.
Depending on the applied nucleophile, different functional groups can b e
incorporated into th e f inal product. If water or an alcohol is used as the
nucleophile, th e corresponding carbo xylic acid or es ter is forme d, w hich is
known as hydroxycarbonyl at ion or alkoxycarbonylation, respectively. Moreover,
carboxylic acids, amines or th iols can also be used as th e nucleophil e , produ cing
the corres pond ing d erivatives of t he carbo xylic acid. The reaction itself is
catalyzed b y several tran sition metals like Fe, Ru, Co, Rh, Ir, Pd and Pt.
However, p alladium as th e catalyst precursor outperforms clearly the others in
its catalytic activity and selectivity and thus, it is in focus of current researc h.
To obtai n high activity and selectivity, the presence and interaction of the

Theoretical Background
5

catalytic system consistin g of the metal p rec ursor, ligan ds and acidic co-
catalysts is crucial, which is still intensively investigated. 15–18
2.1.1 "Carboxy" vs . "Hydride" M echa nism
In order to control th e activity and selectiv ity of any reaction sequence, a
profound kn owledge abou t a detailed mechanism of th e reaction is
indispensable. Initially, two different mechanism s f or th e me thoxycarbon ylation
of olefin s were proposed, which are schematically depicted in Figure 3. 15,19,20

Figure 3. Pr oposed "hyd ride" and " carboxy" mech anism for the methoxyca rbonylation o f
ethene.
On the one hand, the "carboxy" mechanism is b ased on the assumption of the
formation of a palladium-methoxycarbonyl complex ( 5 ) from the CO insertion
into the active p alla dium-methoxy species ( 4 ). The n ucleophili c attack of
methanol into the p a lladium-carbonyl spec ies is also conceivab le to obtain
complex ( 5 ). Sub se quently, an olefin insertion ( 6 ) and methanoly sis step leads to
the corresponding ester and reactivated methoxy species ( 4 ). In c ontrast, the
"hydride" mechanism proposes a pallad ium-hydride ( 1 ) as the activ e catalyst
species. The f ormation of the palladium-alkyl complex ( 2 ) by ol efin insertion
follows a CO i nsertion, forming t he palladium-acyl spec ies ( 3 ). The last step of
the catalytic cycle is the nucleophilic attack of me thanol, res ulting in the
corres pond ing ester and regeneratin g the active p alladium-hydride c omplex ( 1 ).
Based on theoretical an d experimental studies with ethyl e ne as the substrate,
the "hyd ride" mechanism was f ound to d o minate the methoxy carbonylation
reaction. 19,21–23 The "h ydride" mechanism was also conf irmed for other sub strates
like styrene, methyl oleate an d octene. 24–26 Nevertheless, dependent on the

Theoretical Background
6

reaction cond itions and applied catalytic system, th e "carboxy" mechanism
cannot be excluded or both cycles could operate simultanously . 27
It is worth menti o ning th at two dif ferent p roducts can b e obtained u sing
ethylene as substrate: Firstly, the methoxy ca rbonylation leads to the formation
of the low boiling liquid methyl propanoate. Secondly, an alt ernating
copolymerization of ethene and carbon monoxide can occ ur f orming polyketones,
which is a widely used thermoplast with an extra high resilience. Here by, the
chemose l ec tivity of the reaction is d etermined mainly b y the ch oice of an
appropriate phosphine ligand. Electron-do nating and bulky diph osp hines with a
wide bite-angle favors the formation of t he ester over the copolymerisation. 28
2.1.2 Mechanism of Me thoxyca rbonylatio n
In the following, the "hydride" mechanism for the methoxycarbonylation of
olefins is considered in more detail. Hereby, the f ormation of the active
palladiu m- hydride complex, possible deactivation pathways of the catalyst
system as well as the equilib ria between th e different intermediates in the
catalytic cycle are in f ocus, whi ch is il lus trated in Figure 4. Particularl y,
bidentate phosphines are promising li gands for th e methoxycarbo nylation,
leading to a good catalytic performance and se lectivity, where by 1,2 -bis(di-
tert
-
butylphosphinomethyl)benzene (d
t
bpx) as ligand outperforms th e other
diphosphines with its superior li near to branched selectivity. 16 Hence, th e
illu strated catalytic cycle is established for diphosphines. Moreover, acids with
non-coordin a ting anions such as para-toluenesulf onic acid (p-TSA), methane
sulfonic acid (MSA) or trifluoroacetic acid (TFA) act as co -catalyst and are
necessary to perform the methoxycarbonylation reaction. Exemplarily, MSA is
described in the proposed catalytic cycle.
Initially, th e formation of the active pall a dium-hydride species is crucial for the
methoxycarbonylation reac tion, which was in vestigated in se veral studies.
Starting from a palladium(II)-precursor, m ostly the acetate or h alide salt of
palladiu m, the addition of a diphosphine and an acidic co-catalyst leads to the
formation of cationic pall a dium complex ( 7 ), stabilized by th e cis-coordinated
diphosphine and co ordinated acid. Af te r ad dition of methanol, which
coordinates to palladium complex ( 7 ), formaldehyde is eliminated via a
β-hydride elimination. 1 5,23 As a result, the p alladium-hydride complex ( 8 ) is
formed, in w hich the solvent methan ol i s at the free coordination site.
Depending on th e reaction medium and conditions, th e coordinated methan ol
could d issociate, giving th e palladium complex ( 9 ). In contrast, pallad ium(0)-
precursor are also suitab le precursors to form the active p alladium-hydride
complex. Here by, traces of oxygen or add itional oxidizing agents could oxidize
the zerovalent pall adi um precursor to pall adium(II) in the presence of acid. 23

Theoretical Background
7

Moreover, an oxidative addition of p rotonated phosphin e li gand in to zerovalent
palladiu m spec ies could form the active palladium-hydride com plex ( 9 ). 26

Figure 4. Pr oposed "hydride" mechanism for the methoxyca rbonylation of an olefin (green
background), inc luding the formation o f a ctive pallad ium-hydride species (yellow backg round)
and pos sible ca talyst deactivation pathwa ys (red bac kground), L = CO, MeOH, solvent,
coordinating a nion of the a cid or anio n of the palla dium precursor, liga nd.
Indeed, the formation of the active catalyst complex is a d ifficult issue .
However, d ifferent pathways occur presumab ly in p ara llel, dependin g on the

Theoretical Background
8

applied p rec ursor, acid, li ga nd, solvent s, reactants and con ditions li ke
temperature and pressure.
After f ormation of the active p alladium-hydride complex ( 9 ), the first step of
the catalytic cycle is the coordination of th e olefin , giving th e π-complex ( 13 ).
This complex is a reactive intermediate and cou ld not b e observed via
spectrosc opic method s. Af ter that, th e in serti on of the olefin into the palladium-
hydride b ond takes place, forming eith er the linear p alladium-alkyl complex ( 14 )
or the branch e d one ( 17 ). Both complexes are stabi lized by weak β-agostic
interaction. It was sh own that a series of β-hyd ride elimination and olefi n
insertion steps lead to the formation of internal olefins. 24 Furth ermore, based on
the branched palladium -alkyl complex ( 17 ), internal esters can b e formed. Thu s,
the li near to branched regioselectivity of the methoxycarbonylation is
determined by the olefin insertion step. Addition of CO to complex ( 14 ) gives
the palladium-acyl complex ( 15 ) via a insertion of CO into the palladium-alkyl
bond. Notably, the CO in sertion step is reversible, which was observed by NMR
measurements and co nfirmed by DFT calculat io ns. 24 Moreover, d epending on
the partial pressure of CO, the corresponding palladium-acyl-carbonyl complex
can be formed, inh ibiting th e subsequent methanoly sis step. Finall y, the
methanolysis of the pall a diu m-acyl complex ( 15 ) rege nerates the active
palladiu m- hydride complex ( 9 ) and the corresponding linear alkyl ester ( 16 ) as
the final product is eliminated.
It is worth to mention that the proposed catalytic cycle is also valid for the
hydroxycarbonylation of olefins, althou g h the f ormation o f the active pall adium-
hydride species is not in itiated by a β-hydride elimin at ion of the coordinated
methanol. However, the pall a dium-hydride could be formed vi a a kind of water-
gas shif t reaction. The p alladium complex could coordinate CO and water,
givin g a palladium-COOH complex. The sub sequent elimination of carbon
dioxide leads to the active pall a dium-hydride complex. 26,29
2.1.3 Deactivation p athways of hom ogeneous pall adium catalysts
Since deactivation of the active catalyst complex in homogeneous catalysis i s
unavoidable, p art icularly in pall a dium chemistry, a deeper look in to this topic
was taken. An overall review concerning the stabili ty of homogeneous metal
catalysts was publi she d by Robert Crabtree. 30 In Figure 4, just a few possible
deactivation pathways for the p alladium-catalyzed methoxycarbonylation are
shown, leading to a lower amoun t of th e active palladium-hydride species an d
thus, to an overall lower rea ction performance. On the one han d, it was shown
that b ase d on comple x ( 8 ) and after p res surizing with CO, the corresponding
palladiu m- hydridocarbonyl complex ( 10 ) is f orme d. The hydridocarbonyl
complex undergoes dimerization, giving th e palladium dimer ( 11 ), in whi ch CO

Theoretical Background
9

and th e h ydride act as bridging li gand. 29,31,32 However, these species are in
equilibriu m to each other, which is affected by the local concentration s and
conditions. Thu s, the dimer is a kind of reservoir for the formation of th e active
palladiu m- hydride species ( 9 ). Moreover, Claver and coworkers observed that
the amount and type of acid can be crucial for the stability of th e catalyst
system. 15 Dependin g on the basicity of the ligand and strength of the applied
acid, t he d i phosphine can be p rotonated. Hence, a decoordination o f the
diphosphine leads to destabilization of the h o mogeneous p alladium complex and
thus, palladium black is formed in th e reaction mixtu re. Another p ossible
deactivation pathway is the irreversible bimolecular reaction of pall a diu m-
hydride species ( 9 ), which was investigated by Mecking and coworkers. 33 The
produ cts are the fully coordin ated palladium complex ( 12 ), palladium black and
hydrogen, whi ch could hyd rogena te the olefin. Furth ermore, this side reaction is
also possible between the palladium-alkyl complex ( 14 ) and pall a dium-hydride
species ( 9 ), forming the correspondin g alka ne and palladium black.
2.1.4 Kinetic studies
For the design and optimization of chemical reactors as well as the improvement
of the reaction performance , a kin etic analysis of the reaction is essential. A n
empirical model based on a f ormal kin etic app roach, in which a simple power
law is u sed, is th e easiest way to describe th e reaction rate of chemical
transformations. However, catalytic reactions und ergo a series of elementary
steps, forming very reactive in termediates in the catalytic cycle, whi c h make the
description of the kin etics via a power law not reliab le. Furthermore,
preformation steps of the catalyst, catalyst d eactivation process es, in teractions
of different reactants and catalytic as well as non-catalyt ic side reactions are
involved in many metal-catalyzed reactions, which make the u se of a f ormal
kinetic approach only useful in a li mited and narrow concentrati o n range. 34 In
addition, mass tran sfer, especially f or liquid-gaseous reactions su ch as th e
methoxycarbonylation, has to be consid ere d t o get a r eal pictu re of the ki netics.
Hence, kin etic studies have to be p erformed und er reactions conditions, in which
the reaction is not limited b y mass tran sfer. A general approach to study the
kinetics of a chemical transformation is based on a mechanistic ap proach. On
the basis of the reaction mechanism, a mathematical model is developed,
describing the kinetic on a molecular level. All intermediates of th e reaction
mechanism are in volved, in which the different reaction steps in the catalytic
cycle are a ssumed to be reversible and not rate-determining. 35 Not on ly the
description o f on e-site catalytic cycles is possible with this general approach, but
also the kinetic analysis of coupled cycles, competin g cycles, connected cycles as
well as p re-equilibria for instance the formation of the active catalyst complex.
Semi-empirical app roa ches includ e rate-determinin g steps (RDS), irreversible

Theoretical Background
10

steps an d/or th e concept of the most abund a nt species in the catalytic cycle i n
order to reduce the complexity of the mathematical description.
The kinetic an alysis of the methoxycarbonylation reaction was in v estigated in
literature for different substrates an d catalyt ic systems. Morris an d co-workers
studied the methoxycarbon ylation of ethylene, u sing a catalytic system
containing a palladium source, th e li gand d
t
bpx and MSA in a ratio
Pd:ligand:MSA = 1:5:450. 36 Assumin g an irreversible methanoly sis step and
steady-state condit ions f or all catalytic intermediates, a ki netic model is
proposed, in which the methanoly sis step is rate-determinin g with f irst order
concerning MeOH, a fractional order for CO and zero order relating to ethylene.
Furthermore, Cavin ato and co-workers investigated th e methoxycarbonylation
of cyclohexene with a catalyt ic system containing palladium acetate,
triph en ylphosphine (TPP) and p -TSA, showing also the methanolysis as RDS. 37
In contrast to the methoxycarbon ylatio n of ethylene, a linear dependency
concerning cyclohexene was found. Rodionova and co-workers stud ied th e same
catalytic syste m for the methoxy carbonyla tion of cyclohexene, i nvestigating
additionally the impact of TPP and p-TSA concentration on th e reaction rate. 38
Similar results were o btained compared to the investigati ons of Cavinato and
co-workers. However, a complex d ependency of TPP and p -TSA concentration
was imp leme nted in th eir kin etic model, suggesting ligand exchange and
decomposition processes of th e active catalyst complex. Moreover, the
methoxycarbonylation of the long chain olefin 1-hexene h as been studied by
Baricelli and co-workers . 39 It was f ound that the methanolysis step is rate-
determining. Hereby, a rate law was derived as shown in equat ion 1. The
parameters a,b and c are constants, in cluding th e product of di fferent rate
constants and equilib r ium constants.
 =  [  ][  ][  ] [ ]
1 +  [  ] +  [  ] []

(Eq. 1)
Recently, the rate law for the methoxycarbonylation of 1-decene was d erived
using a semi-em pirical approach for the catalytic system Pd/d
t
bpx. 40 Not only
the methoxycarbonylation to the linear ester but also reaction ne twork to th e
branched ester and the isomerization of 1-decene was consid ere d. In agreement
with th e investigations of Baricelli and co-workers, an inhibiting effect of the
substrate 1-decene was observed as seen in equation 2. Furthermore, it was
found that the isomerization of 1-decene is in hibited by an increased partial
pressure of CO (see equati o n 3). The coefficient s d , e, and f are temperature-
dependent, d escribing the produ ct of different equilib r ium constants. The
coefficients k methoxy. and k isom. are th e correspond ing rate constants for the
methoxycarbonylation and isom erization, respectively.

Theoretical Background
11

  . =  . [  ][  ][  ] [ ]
1 +  [  ]

(Eq. 2)
  . =  . [ ]  [ 1 −  ] − [ − ]
 
1 +  [  ] +  [ ]

(Eq. 3)
In summary, it is mentionable that the mathematical description of the reaction
rate depends on the applied catalytic system and the substrate. However, the
methanolysis step seem s to b e t he rate-determining step in the catalytic cycle of
the methoxycarbonylation as showed for different substrates and ligands.
2.1.5 Industrial appli cation
The production of methyl methacrylate (MMA) represents th e most p rominent
example for an industrial appli catio n of the methoxy carbonylation reaction,
commercialized by Lu c ite International with the Alpha process in 2008. MM A is
the building block for the p roduction of the polymeric poly-methyl methacrylate
(pMM A ), which is mainly used as a substitut e of glasses. Sin ce pM MA d oes not
interact with the hu m an body, it is also applicable f or artificial lenses, bone
cement, and dentures. 41 The ap plication of MMA with oth er monome rs offers
access to many other poly mers with uniq ue p roperties, which are used in
specialized end products. The worldwide demand for MMA is steadi ly increasing
and reached 3 million tons per year in 2007. 42 Besides the Alpha process, there
are some tradition al synt hetic routes still existin g. For instance, the ACH
process wa s developed in the late 1930s, using acetone and the extrem ely toxic
hydrogen cyanide and sulphuric acid, which is still the most wid ely used p roce ss
for MMA production . In contrast, th e Alpha proce ss is a gr een and sustain a ble
alternative, involving a two-step process and starting with easily available
feedstocks. In a first step, ethylene is catalyt i cally converted with methanol and
carbon monox ide to methyl p ro pionate. Hereby, a catalytic system comprising a
palladiu m source, the diphosphine d
t
bpx, and MSA is used, offering a high
activity and se lectivity. Since the b oiling point of t he produced methyl
propionate is low, the product can be easily separated via distillation and t he
catalytic system can be re cycled. In a second condensation step, methyl
propionate is heterogeneously converted with formaldehyde to the correspond ing
MMA. Lucite International h as buil t a plant with an annual capacity of 120.000
tons MMA in Singap o re and has advanced p lans f or a second plant producing
MMA. 41
Inspired by this process, oth er feedstocks have a high industrial potential for t he
Reppe carbonylation in the future. Rece ntly, Walther p ublished an article
focussing on renewable feedstocks based on plan t oil s. 43 Diesters can be obtained
after the functionalization with the methoxycarbonylation reaction, which are

Theoretical Background
12

platf orm chem icals for the corres pondin g dia cids, diols or diamines. With these
intermediates, p olyme rs like polyamid es , polyu rethanes or polyesters can be
produ ce d with established procedures based on renewables. Furthermore, the
hydroxycarbonylation of styrene derivatives off ers easy access to arylp ropionic
acids like Ibuprofen, Naproxen or Ketoprofen, which are pharmaceutical active
ingredient s in anti-inflammatory drugs. 44,45
2.2 Green Chemistry
For decades, the final chemical p roduct and its function were paramount in
classical chemistry. But classical chemistry has changed due to the pioneering
work of Paul T. Anastas and John C. Warner at the end of the 1990s. They
introduced the term Gre en Chemistry, which is d efined as th e "design o f
chemical products and p roce sses to reduce o r elimin ate th e u se and generation
of hazardous substances". 1 The concept of Gre en Chemistry has th e goal to
achieve sustain ability in the field of chemistry and its f ollowing sectors. To
reach th e goal, the Twe lve Principles of Green Chemistry were introduced as a
guideline f or chemists, in cluding rules for designin g sustainable chemicals and
processes (see Figure 5).

Figure 5. The Twelve Princ iples of Green Che mistry.
Rule n umber 1 is wast e prevention. Especially in organic synt hesis, plent y of
toxic solvents are used, which have to be c leaned after their use. To qu antify
the eff iciency of waste prevention in chemical processes , S heldon and co-workers

Theoretical Background
13

introduced the E-Factor (En vironmental Impact Factor), which is d e fined as th e
mass of waste (reage nts, solvent s, additives, and requi red fuels or energy)
produ ce d du ri ng the whole process related to th e mass of the final p roduct. 46 In
fine chemistry, th e E-factor reaches often values above 50, meaning th at f or the
synthesis of 1 kg o f the d esired p roduct 50 kg of waste is produced. Designing
synthetic routes with a high atom ec onomy is d irectly linked to waste
prevention, whi ch represents th e s ec ond of the Twelve Principles. An easy
methodology to achieve a high atom economy is the u se of catalysis in stead of
stoichiometric reactions (Prin ciple 9). Furtherm ore, catalysis can help to
improve the selectivity, p reventing undesired side p roducts and increase the
atom economy. A p oint, which is considered with much eff ort in res earch, is the
use of safer solvents for chemical synth es is (Prin ciple 5). In fact, solventless
systems are the best solution , what reac hes its limits in many chemical
transformations. Instead, greener solvent s like water or supercritical flu i ds are
tested as an alternati ve to organi c solvents. Sin ce the safer solvent s must be
isolated af ter the use from the desired p rod uct, the separation process got in to
the f ocus of green chemists . Conn ec ted to that, the p roce ss should be d esigned
for energy efficiency, operatin g chemical reaction and separation p rocess es at
mild p res sures and temperatures (Principle 6). Furth ermore, chemicals should
be developed, min imi zing the risk to the envi ronment an d human, while
maintaining the fun cti on of the final p roduct (Principle 4). Not only the final
produ ct itself but a lso the route to it sho uld be designed in a less hazardous way
with less impact for human health and environment (Prin ci ple 3). As a result,
processes ar e safer an d acc idents can be prevented (Principle 12). Besid es that,
chemicals and process es shou ld be designed considering th e use of renewable
feedstocks, reduction of derivatization, design for biod egrada tion and online
monitorin g for pollution prevention.
In summar y, the Twel ve Prin ciples are a guid eline to meet th e req uirements of
Green Chemistry. It is not wise to consid er ea ch point independently. In
contrast, all prin ci ples are interconnected, constitu ting t he framework of Green
Chemistry. These prin ciples of Green Chemistry, realized in part or even
completely, can lead not only to ecological advan tages and social acceptance of
chemistry but also to processes which are economically beneficial.
2.3 Multiphase S ystems
As mentioned, th e search f or an alternative, environmentally friendly reac tion
media f or organic reactions is of high interest in th e current researc h, meeting
the requirements of green and sustain able chemistry. Particu larly, multiphase
systems f or metal-catalyzed organic transformations combine advantages such
as th e substitution of conventional organic solvents, h aving of ten toxic
properties, and the possibility of recycling the catalytic system, which prevents

Theoretical Background
14

waste. Besid es the ap plication of multiphase systems for efficient catalyst
recycling, several other techniques are reviewed such as immobilization of the
catalysts on solid sup ports or organic nan ofiltration. 47,48 In the case of
multiphase systems, t he reaction system consists id eally of two ph ases, one
produ ct containing phase, which h as p referably no additional organic solvent,
and a second phase containing th e catalytic system, which can b e re cycled via a
liquid/liquid phase separation several times. In order to reach a high separation
efficiency, the homogeneous catalyst is functionalized with specific
groups/ligands to immobilize quantitatively the catalyst into the catalyst
containing phase. Despite th e high p otential of mul tiphase systems for
homogeneously catalyzed reactions, the use of th ese systems is boon and b ane at
the same moment. On th e one h and, the recycling and reuse of the often
expensive catalytic system in its active form is the main be nefit u si ng
multiphase systems, which is imp ortant for ecological and economic reasons.
Furthermore, e nergy-demandin g separation processes such as distillation can be
substituted through a non -energy intensive liquid/liquid phase separation. As
well, conventional solv ents, whi ch have of ten toxic p ro perties, can be avoided b y
the u se of multiphase systems, particu larly if water is applied as the catalyst or
produ ct containin g phase . On t he oth er h and, the use of mult iphase systems in
lab and indu stria l p rocesses bear some drawbacks and diff ic ulties. The catalytic
performance is mainly determined b y th e solubility of the substrate in th e
catalyst containing phase . The lower th e solubility of th e substrate, the lower is
the reaction rate. Moreover, since two phases exist, the catalytic activity can be
limited by mass transfer of the substrate into th e catalyst phase, lowering th e
catalytic performance. Hence, the determination of th e kinetics is m ore complex
in multiphase systems compared to ordinary organi c solvents. Not only the
microkinetics of the reaction has to be investigated, but also th e rate f or mass
transport is important to obtain the macrokinetic picture, describing the
catalytic performance. Anoth er point to cons ider in multiphase systems is the
catalyst stabili ty, which can be p roblematic, especially if water is a pplied as the
solvent. Moreover, the com patib ility of th e app lied multiph ase syste m with th e
substrates, p roducts an d reaction itself has to be consid ere d to avoid side
reactions and maintain product stability. These points h i nder the fast process
development of organic reactions in mul tiphase systems, whi ch h ave to be
solved in future to establish these systems in indu stria l processes.
In the f ollowing, some mul tiphase systems are p resented an d examples for
catalytic tran sformations in these systems wit h subsequent catalyst recycling,
particularly for the Rep pe carbonylation, are giv en. S i nce surfactant based
systems ar e the main element of this thesis, the focus has been set on these
systems .

Theoretical Background
15

2.3.1 Aqueous biphasi c systems
The easiest ap proach to p erform organ ic reactions i n multiphase sy stems is th e
application o f aqueous biphasic systems, in whi ch the homogeneous catalyst is
modified with water-soluble ligands to imm obilize it into th e aqueous phase.
The Ruhrchemie/Rhone Poulenc (RCH/RP) process represent s a milestone of
aqueous b i phasic systems on in dustrial scale, developed i n th e 1980s. Propylene
is converted with synthesis gas (a mixture of CO and H 2 ) to butanal, using a
rhodium catalyst, which is immobilized with the water-soluble ligand 3,3',3'' -
Phosphanetriyltris(benzenesulfonic acid) trisodium salt (TPPTS) in the aqueous
phase. The product f o rms th e upp er p hase an d can b e continuously separated
via f acile li quid/liquid ph ase separation , whereas the catalyst can be re cycled
back to the reactor. The leaching of the rhodium catalyst is lower than 1 ppb. 49
Inspired by this p roce ss, the transfer of this concept to the methoxy - and
hydroxycarbonylation was studied in academia. The first attempts to p erform
the hyd rox ycarbonylation of alk enes in aqueous biphasic systems were
independently reported in 1997 by th e groups of Mortreux 50 and Sh eldon 51 . In
both groups, TPPTS has been used as the ligan d to immobilize the
homogeneous palladium catalyst in th e aqu e ous phase, testing several substrates
like propylene, styrene an d its d eriva tives. However, recycling experiments were
not reported and the produ ct was extracted with an organic solvent,
subsequently. In cont rast, Chaudhari and co-workers have in ves tigated the
hydroxycarbonylation of different vinyl aromatics with pall a dium as the
catalyst, modified with pyridine carboxylate and TPPTS. 52 The biphasi c
mixture was composed of water as the catalyst p hase and toluene as the organic
phase. Wi th that, subsequent recycling experiments were performed via
liquid/liquid phase separation and the pall adium loss was lower than 0.1 ppm.
Besides propylene and styrene derivatives as substrates for the
hydroxycarbonylation, several other alkenes, espec ially linear α-olefi ns, h ave
been also investigated. Sh eldon and co-workers have studied the
hydroxycarbonylation of 1-octene in aqueous biphasic systems, leading to a very
low catalytic activity, caused by the low so lubility of 1-octene in the aqueous
catalyst ph ase. 53 With the introduction of th e b identate water-soluble
SulfoXantPhos (SX) ligand by van Leeuwen and co-workers 1998, leadin g to an
increased regioselectivity for lin ear α-olefins an d enhanced stability of th e
catalyst complex, the application of biph asic palladium-catalyzed
hydroxycarbonylation have got much more atten tion. 54 Claver and co-workers
have investigated the hydroxycarbonylation of styrene with novel su lfonated
diphosphines and found that th e catalyst can be rec ycled several times. 55
However, th e u se of an aqu eous b iphasic system, in whi ch the catalyst system is
immobilized in the aqueous p hase, is limited to substrates being slightl y soluble

Theoretical Background
16

in the catalyst ph ase. To overcome li mitations by the solubility of th e sub strate
and mass transfer, plent y of innovative multi phase systems have been
developed. S ome of them are presented in the f ollowing sections. Furth ermore,
aqueous b iphasic systems are n ot suitable for the hyd roes terification of alkenes
due to th e formation of the corres pond ing acid as a side p roduct. Hence, som e
studies with organi c/o rganic biphasic systems are available. Monflier an d co-
workers have in vestigated the hyd roesterification of several lin ear α-olefins
und er p ol yol/organic ph ase biphasic cond itions. 56 For this pu rpose, the ligand
TPP, functionali ze d with dimethylamin o groups, was used to immobi lize the
catalytic system in th e poly ol phase. The polyol, mainly ethylene gly col, acts as
both, the reactant an d th e ph ase for catalyst immobilization. Even biob ased
polyols like isosorbide can b e tran sformed into the corresponding diester und er
biphasic conditions. 57
2.3.2 Surfactant-based multiphas e systems
A promising tool to overcome p roblems cau sed by ordinary biphasic systems,
especially mass trans fer li mitations, is the u se of surf ace active agents
(surfactants), whereby th e se lection of an appropriate surfactant is crucial f or
the catalytic activity and separation behavior. For instance, th e charge, costs,
physiochemical properties such as the critical micelle conce ntration (CMC) and
the environmental impact have to take into account for the sel ec tion of an
suitable surfactant for homogeneously catalyzed organi c reactions in water. A
whole zoo of different surfactant s is available, making the selection of the
surfactant rather difficult. In p rinciple, surfac tants can be classified b y their
charge in to cationic, anionic, zwitterionic and nonionic ones, whereby classical
representatives are cethy ltrimethylammonium bromide (CTAB), sodium dodecyl
sulfate (SDS) or Triton X-100.
In general, th ere are t wo di fferent possibiliti es to perform organi c reactions in
surfactant-based media. On t he one ha nd, an aqueous mice llar solution is
formed by adding a surfactant to water, if the surfactant concentration is above
the CMC. Mi celles are aggregates of surfactants, acting as nanoreactors due to
the different hydrophobicity in th e core of t he micelles. The size a nd shape of
the f ormed micelles are inf luence d by the type and concentration of th e ap plied
surfactant. Thus, small amoun ts of th e organic substrate can be solub ilized into
the n a noreactors. Due to the e nhanced solubility of the organic substrate in th e
aqueous phase, the organi c tran sformation proceeds with much faster rea ction
rates. A sub se quent separation of th e dissolve d catalyst complex and the organic
produ ct can be realized with micellar enh a nced u ltrafiltration (MEUF) or cloud
point extraction (CPE). However, only small amoun ts of the organic substrate
can be app lied to ob t ain a macroscopic homogeneous reaction system, which
makes this app roach not app licable to the produ ction of large-scale chemicals.

Theoretical Background
17

The second approach is based on adding larger amoun ts of oil to an aqueous
micellar solution , leading to the formation of microemulsion systems . The basics
of th es e systems were elaborately d es cribed in PAPER 11 . Microemulsions are
mixtures of two immiscible liquid s, predominantly water and oil, with an
amphiphile as th e e mulsifier. The phase behavi or can be easily d es crib ed by the
Gibbs p hase prism in which th e base of this prism repres ents the te rnary system
of oil, water, and the amph iphile (Figure 6, left). The composition of the ternary
system is charact erized by the surfactant co ncentration γ, denoted as th e mas s
fraction of the amphi phile to the total mass of th e microemulsion system
(Equati o n 4), and the oil mass fraction α in the water-oil mixture (Equati o n 5).
 =  
   +  +  

(Eq. 4)
 =  
  +  

(Eq. 5)
The Gibb s phase p ris m can be reduced to Kah lweit´s fish diagram whi ch is
created by cutting the Gibbs phase p ris m at a fixed oi l ma ss f raction α,
exemplarily illustrated in Figure 6 (right).

Figure 6. Gibbs p hase pris m for a mic roemulsion syst em consis ting o f oil, wate r, and a nonionic
surfactant (left pic ture), cu t of the phase prism at α=0 .5 (right picture) , taken fro m PAPER 11 .
The ph ase b oundaries resemble the shape of the fish where the body of the fish
represents th e three-phase region of the microemulsion system. In the fish-
diagram,   marks th e minimal concentration of surfactant whi ch is n eeded to
form a micro emulsion system. The solubility of the n onionic surfactant changes
with th e temperature causing th e transiti on of th e system b etween d ifferent
phase states . At low temperatures th e nonion ic surf actant is more hyd rophilic
and thus mainly soluble in the water phase, forming an oil-in-water
microemulsion with an excess oil phase (2Φ). In contrast, increas ing the
temperature leads to a water-in-oil microemulsion with an excess water p hase
( 2
 Φ) caused by the higher solubil ity of the surfactant in th e corresponding oil
phase. In b etwe en, the mixt ure f orms a three-phase region in which the mid dle

Theoretical Background
18

phase is the surfactant-rich microemulsion phase. At high surfactant
concentrations, the microe mulsion system r eaches a macroscopic one phase
state. The min imal surfactant concentration, at which a one phase
microemulsion is ob tained, is d enoted with   with the associated temperature 
 .
Since th e d ifferent phase s can be converted in to each other by changing the
temperature, th e reaction system can b e adapted for diff ere nt requirements.
Obvi o usly, the recycling of the catalyst complex or other additives and t he
separation of the p ro duct can be easily indu ced by a temperature-controlled
liquid/liquid phase separation.
To th e best of our knowledge, surfactant based multiphase syst ems ar e not
applied so far in th e hyd ro xy- or methoxycarbonylation reaction. However,
several other organic reactions are perform ed in these systems su ch as C-C
coupling reactions 58–60 , hydroly ses 61 or hyd rogenations 62,63 . Furthermore, the
application o f surfactant b ase d systems f or organic transformations is reviewed
in li terat ure. 64–66 Even the synth esis of p harmac eutical active ingredient s (API)
can benefit from the ap plication of micellar systems in an ecological and
economic pers pective, s howed rece ntly b y Novartis Pharma AG . 67
2.3.3 Miscellaneous mul tiphase sys tems
Besides the addit ion of surfactants as p hase transfer agents, th ere are several
further p ossibilities to overcome the limits of ordinary biphasic systems. In
particular, switchable solvents, whi ch change the p hysical properties b y an
external stimulus like temperature or pressure, are in focus of current rese arch.
This includ es for instance cyclod extrin modified aqueous biph a sic syst ems,
which is in tensively investigated by the group of Mo nflier and coll aborators. 68,69
Cyclodextrins are b iobased compoun ds from sugar molecules, which are li nked
together forming a ring. Due to the ring formation, th e core of the cyclodextrins
acts as a li pophilic carrier, whereby the external surface facili tates the water
solubility. Dependent on the number of sugar molecules, the size of th e ring can
be varied to ad apt it to the size of th e molecule, whi ch should be tran sferre d to
the aqu eous ph ase such as th e substrate. Hence, the r eaction performance is
enhanced by hampering mass tran sfer limitation s and the p oss ibil it y to recycle
the catalyst is giv en . Interestingly , a thermocontrolled approach is possible in
which th e cyclodextrins act as the carr ier of the catalyst. 70 At high
temperatures, the carrier releases the ligand-modi fied organometallic catalyst
and thus, the reaction takes p lace in th e organi c p hase. Af terward, th e
temperature is de creased, leadi ng to an encapsulation of the catalyst in the core
of the cyclodextrin. Hence, the catalyst can be immobilized in the aqueous phase
and recycled for a n ext catalytic run. The applicability of cyclode xtrin-based
biphasic reaction media has been studied for th e hydroxycarbonylation of 1-

Theoretical Background
19

decene. 71 The reaction p erformance is mainly in fluenced by the solubil i ty o f t he
cyclodextrin in b ot h, th e aqueous and organi c phase. Hence, chemical
modifications of cyclodextrins b y substituting the hydroxyl groups with other
fun ct ional moieties was shown to be effective for improving the catalytic
activity. Furthermore, the regioselectivity toward the terminal acid can b e
significantly increased b y shielding the internal double bond through the
encapsulated sub strate. Recycling experiments h ave been successfull y done,
whereby the palladium leaching was less than 1 pp m. Howe ver, the leaching of
the applied ligand TPPTS was rather high with 10 pp m.
Moreover, th ermomorphic multicomponent systems (TMS ), which were
introduced in catalysis by Behr and co-workers, are p romising conce rning the
recycling of h omogeneously dissolved catalyst systems. 72 The TMS benefits from
the miscibility gap between a p olar and nonp o lar organic solvent, whi ch is
controlled b y temperature. Heating of th e solvent mixt ure leads to a
homogeneous reac tion media, in which th e reaction can tak e place withou t any
mass transfer limitations. After the reaction, the mixtu re is cooled and a phase
separation of the TMS occurs, in which t he catalyst and product are located in
different ph ases. Thus, the catalyst p hase can b e re cycled f or a n ext run.
Hereby, the selection of appropriate solvents f or TMS is crucial in order to
adju st the separation in a certain temperature wind ow and to obtain low
leaching of the catalyst into th e product ph ase . Behr and co-workers h ave
studied t he methoxycarbonylation of methyl oleate in a TMS composed of
methanol and decane. 73 The selection of methanol as the polar p hase is
beneficial since methanol acts also as the s ubstrate in this reaction. The proof of
concept for catalyst recycling was shown in th ree consecutiv e recyclin g runs.
However, the leaching of pal ladium and phosphorous into the product phase was
3 ppm and 2 ppm, respectively, which is too high for an industrial application.
Afterward, the methoxycarbonylation of methyl 10-u ndec anoate has been
investigated, in which eight recycling run s could be p erformed, due to th e
addition of co -catalyst after each recycling procedure. 74
In th e last years, th e use of sup erc ritical carbon dioxide (scCO 2 ) as reaction
media op ened a wid e field for homogeneous catalysis. 75 Besides r eaching high
activities and selectivities for gas-liqu id reactions, f or instance, h ydrogenation 76
and hyd ro formylation reaction s 77 , th e u se of scCO 2 offers the ad vantage to
recycle the homogeneo us catalyst. Due to th e creativi ty of researchers, several
methods are avai lable for the recycling of the catalyst from scCO 2 based reaction
media, including for instance lowering the pressure for catalyst precipitati o n or
using b i phasic reaction media with scCO 2 as one phase. The Rep pe
carbonylation has also been investigated in scCO 2 . Estorach and co-workers
have stud ie d the methoxycarbonylation of li near alpha olefins in scCO 2 , using
fluorinated ligands. 78 As a r esult, the catalyst complex shows an enh anced

Theoretical Background
20

solubility in the supercritical f luid and thus, better reaction ra tes could be
obtain e d. Furthermore , th e methoxycarbonylation o f norbornene in scCO 2 has
been d escribed by the group of Li. 79 However, b oth groups d id not show any
recycling experiments, which can be expected for the Reppe carbon y lation in
scCO 2 based reaction media in near fu ture.

Experimental Part
21

3. Experimental Pa rt
3.1 Chemicals
The ap plied chemicals, the supplier and the p urity are listed in the appendix
(Table A1-A4). All chem icals were used as received with out further purification
steps.
3.2 Determination of C MC
The bubb le pressure tensiometer BP50 of the company
Krüss
was u se d to
determine the critical micelle concentration (CMC) of th e a pplied surfactants.
For th is purpose, aqueous solut ions with different concentrati ons of the
corres pond ing surfactants were prepared and measured. The d ynamic surf ace
tension of the solution was measured, starting at th e surface age of 30 ms and
endin g at 16 s. After each measurement, the capillary was flushed with air for
5 s. Three valu es w ere measured at each surface age and the average was
calculated. At a surfac e age of 14 s, when the surf ace tension remains constant,
the surface tension value was taken and plotted versus the concentration of th e
surfactant to determine th e CMC. All reported valu es were measur ed at 25 °C
and are indicated as moles of surfactant per volume.
3.3 Investigation on th e phase beh avior
The investigations on the phase behavior were performed in 10 mL S chlenk
tubes. In case of n onionic surfactants as ph ase transfer agents, the co-solvent
dodecane (2.25 g), 1-dodec ene (0.75 g), the surfactant, sodium sulfate (Na 2 SO 4 )
and the co-catalyst methanesulfonic acid (MSA) were weighted into th e Schlenk
tube an d f lushed with Argon. A stock solution of th e p rec ursor Pd 2 (al lyl) 2 Cl 2
and the ligand SulfoXantPhos (SX) was prepared in water with standard
Schlenk technique and stirre d overnight. The catalyst solution (3.0 g) was
added to the Schlenk tub e under Argon c ounterflow, simulating the in i tial
reaction mixt ures and th e tub es were clos ed with a septum. Aft erward, th e
Schlenk tubes were placed in a water b at h and the phase behavior of the
microemulsion systems was in vestigated in a temperature range between 50 °C
and 90 °C in 1 °C steps. For that, the temperature of the water bath was
adju sted as d esired, then the tubes were shaken and the p hase separation was
observed visually after 10 minutes. In the same manner, th e phase behavior was
investigated f or the ionic surfactant s using th e co-solvent octane (2.25 g),
1-dodecene (0.75 g), the ionic surfactant, and the co-catalyst methanesulfonic
acid (MSA) . A stock solution o f t he p re cursor Pd (OAc) 2 and the l igand

Experimental Part
22

SulfoXantPhos (SX) was prepared in water with stand ar d Schlenk technique,
which was added through a septum into th e Sc hlenk tube.
3.4 Preformation of t he Catalys t for Carbonylatio n Reactio ns
The catalyst precursor Pd (OAc) 2 or Pd 2 (a llyl) 2 Cl 2 and the ligand S X were
evacuated an d flushed with argon three times in a Schlenk tube. The degassed
polar phase (methanol an d/or water) was added through a septum and the
reaction mixt ure was stirred overnigh t. A homogenous green solut ion indicates
the formation of the catalyst complex.
3.5 Setup for Carbonyl ation R eactions
All experiments were carried out in a 100 mL stainless steel autoclave built by
Halmosi GmbH. An overview of the reactor setup is given i n Figure 7.

Figure 7. Experimental setup fo r methoxy- a nd hydroxyca rbonylation reactio n.
The autoclave ( 10 ) is equipped with a gas dispersion stirrer, a PTFE b affle to
ensure th e dispersion of the reaction mixture, and a PTFE in la y to avoid t he
formation of pallad i um black at th e inner surf ace of th e reac tor wall. To
maintain isobaric reaction conditions a pressure tran smitter ( 4 ) is connected to
a mass flow controller ( 3 ) to the reactor. Fo r a f ast in itial p ressurization of the
reactor with carbon monoxi de, a b ypass was installed ( 6 ), whic h can be
controlled with a pressure indicator ( 5 ) c onnected d irectly to the reac tor.

Experimental Part
23

Additionally, the autoclave has connections f or sampling ( 13 ), in er tization ( 7 a )
and the injection of reactants ( 12 ) under n itrogen counterflow. A process control
system moni tors all process- and the correspond ing set-values li ke pressure,
temperature, gas flow and stirring speed and records th e d ata. A pressure relief
valve ( 8 ) is used to limit the p ressure to 60 bar. After finishing t he reaction, the
toxic gas can be exhausted ( 9 ) to the ventilation of the fume hood. For safety
reasons, th e gas containers ( 1 ) are located in a gas cyl inder cabinet, equipped
with a gas alarm d evice, in which th e gas c harge can be disconnected with a
pneumatic valv e.
3.6 Experimental P rocedure for C arbonyla tion Reactio ns
In a typical experiment, the co-solvent, the substrate, the surfactant, n onane as
internal standard (300 mg) and MS A as co- catalyst were weighted into the
PTFE in lay and introduced to th e reactor. After evacuation and flu shing the
reactor with nitrogen three times, the catalyst solution was injec ted with a
syringe und er nitrogen coun terflow. Under stirring at 200 rpm, the reactor was
heated up to the desired reaction temperatu re and pressurized with carbon
monoxide. Af ter reachi ng the process values, the stirrer speed was increased to
1200 rpm, marking the start of the reaction . Samples were tak en at f ixed time
intervals, diluted with acetone and centrifuged in order to p rec ipitate the ligand
from the sol ution. GC analysis was performed on a Shimad zu GC2010 Plus with
a FID (f lame ion ization detector) packed with a Restek RTX5-MS column
(30 m × 0.25 mm × 0.25 µm). Nonan e was used as in ternal stand ar d to
calculate th e conversion of dodecene, yield of acid and ester, che moselectivity
and linear to branched regioselectivity (l:b), expressed as the ratio of linear acid
to the sum of linear and bran ched acid, as shown in equations 4-7.
 (  ) =   (  )    (  )
  () (Eq. 4)
 (  ) =  ,
  () (Eq. 5)
  (  ) =   (  )
( ) (Eq. 6)
  : (  ) =    (  )
   (  )     (Eq. 7)

Experimental Part
24

3.7 Determination of C at alyst L eaching a nd Produc t Distribu tion
After finishing the reaction, the reactor was cooled down, depressurized, and
flushed with nitrogen. The reaction mixture was f illed in to a graduated cyli nder,
which was closed with a septu m. After compl eted ph ase separation, GC samples
were taken from both phases to determine th e distributi o n of th e product. The
nonp o lar phase was transferred into a round bottom flask, weighted, and
distilled under redu ced pressure (3.6 mbar, 180 °C). The residue was d igested
with 1 mL nitric acid (65 wt%), 3 mL hydrochloric acid (37 wt%) an d 2 mL
sulfu r ic acid (96 wt%) and filled up to 20 mL with water (HPLC grade). The
solution was analy ze d by inductively coup led plasma o ptical em ission
spectrometry (ICP-OE S) for pall adi um and p hosphorus concentration using a
Varian ICP-OES 715 ES in strument. An external calibration was d one with
standard solutions of palladium and phosphorus. The concen tration of
palladiu m and phosphorus were measured at a wavelength of 363.5 and
213.6 nm, respec tively. The results are stated as th e amount of p a lladium and
phosphorous in the nonpolar phase denoted in parts per million (ppm).
During t he continu o us miniplant operation, the produ ct stream was collected for
8 h, transferred to a flask and distilled under reduced pressure (4 mbar). The
residue was solu bilized with h ydrochloric acid (9 mL), 65 wt% n itric acid
(3 mL) and sulfuric ac id (6 mL) in the f lask and filled up to 50 mL with water
(HPLC grade) . The solut ion was analyzed with ICP-OES as described ab ove
and results are denoted as parts per billion (ppb ).
3.8 General proced ure of the Alkaline Hyd rolysis
The main p art of the setup for the alk aline h ydrolysis is a 40 mL d ouble-wall
reactor to adj ust the temperature via a thermostat. The sub strates can b e
injected th ro ugh a two-way valve at the reac tion temperature, whereby th e
mixture is mechanically stirred. To follow the reaction progress the condu ctivity
is measured
in-situ,
using a conductivity elec trode f rom th e compan y WTW.
The thermostat and the conductiv i ty p robe are connected to a computer to
monitor the reaction progress. To perform th e reaction, a st ock solution
containing th e surf act ant and sodi um hyd ro xide (4 mmol, 1 eq.) was filled in to
the reactor, stirred mechanically and h e ated up to the desired reaction
temperature. Immediately af ter reaching the reaction temperature, th e substrate
methyl decanoate (4 mmol, 1 eq.) was inj e cted via a syringe into the reactor.
The bulk volume was 20 mL for each experiment. The reaction was stopp ed
when the conductivity remains constant, or latest after 24 hours.
Since the conversion depends linear on th e cond uctivity of the mixture, th e
conductivity was measu red to determine th e conversion of me thyl decanoate to
sodium d ecanoate. For th at, sodium hydroxide, which main ly contributes to the

Experimental Part
25

conductivity of th e mixture, and the product sodiu m d ec anoate were mixed,
adapted to th e concentrations from th e previous section, simulatin g d ifferent
conversions between 0% and 100%. After waitin g fou r minutes for temperature
equilibriu m, the corresponding conductivity was measured at 40 °C, 60 °C and
80 °C and p lotted versus th e associated conv ers ion. A two-poin t calibration was
done for th e cation ic surfactants, mixing the tenf old critical micelle
concentration (CMC) of the correspond i ng s urfactant, sodium hydroxide, and
sodium decanoate and measuring the conductivity at 80 °C.

Results and Discussion
26

4. Results and Di scussion
4.1 Green Chemistry and InPR OMPT
In the sense of sustainability and Green Chemistry, th e collaborative researc h
center called InPROMPT (Integrated Chemical Proce sses in L iquid Mu ltiphase
Systems) was established in 2010, aiming f or the environmentally friendly
produ ctio n of chemicals. The overall aim of InPROMPT is th e d ev elopment of
phase systems for an efficient catalyst recyclin g in its active f orm by a simple
phase separation , meetin g the requi rements of Green Chemistry. Of special
interest are surf acta nt-based multiphase systems , thermomorph ic solve nt
systems , an d pickering emulsions. The schematic p roce ss conc ept for the
hydroformylati o n of long-chain al kenes, which was investigated as a b enchmark
reaction in the first funding p eriod, is shown in Figure 8. Multiphase systems
offer th e p oss ibil ity to separate the p roduct by an easy p hase sepa ration. The
expensive catalyst complex can be eas ily recycled back to the reactor for further
use.

Figure 8. Schematic proce ss concept for t he hyd roformylation of long- chain alkene s in
microemulsio n systems ( PA PER 5 ).
Besides the chemical and physical fund amentals of th e novel p hase systems and
the catalysis in such a system, the design and development o f continuous
produ ctio n processes as well as their optimization and cost evalu at ion are in th e
focus of th e p roject. As an associate m ember of th e collab orative research
center, I was in volved in the d evelo pment of surfactant-based multiphase
systems for dif ferent homogeneously catalyzed reactions, f inding suit able
reaction media and appropriate reaction and separation conditions.

Results and Discussion
27

4.1.1 Status Quo - H ydroform ylation in Micr oemul sion Systems
The app licability of microemulsion syste ms as reaction media for me tal-
catalyzed reactions was shown in detail for the h ydroformylation of 1-dod ecene ,
mainly in the doctoral thesis of Pogrzeba. 2 The main f ocus was set on th ree key
aims:
1. Understanding the role of the nonionic surfactant during catalysis
2. Analyzing the kinetics of the hydroformylation in microe mulsion systems
3. Transferring the lab scale results in a continuously operated miniplant
The corres pond ing results for the h ydroform ylation of 1-dodecene can be found
in PAPER 3 , PAPER 4, PAPER 5 and PAPER 8 . A microemulsion system
containing water, the substrate 1-dodecene and Marlipal 24/70 as phase tran sfer
agent was found to be suit able f or th e hydroformylation reac tion. Additionally,
sodium sulfate was u se d to facili ta te and acceler ate the phase sep aration for
catalyst recycling. In order to f acilitate a fast proce ss development for catalytic
reactions in microemulsion systems, a better un derstanding of catalysis in such
systems is necessary, whi ch is presented in PAPER 5 an d PAPER 8 . Th e
results reveal that th e amount and type of nonionic surfactant are crucial for
the catalyt ic activity of the h ydroformylation reaction. Int ere stingly, the p hase
behavior of the microemulsion system has n o impact on the reaction
performance. Instead, the catalyt ic activity is determined b y the in terfacial area
between water and oil, main ly influenced by the surfactant concentration, and
the local concentrations of the substrate as well as th e active catalyst complex
at th is interface, affected by the physicochemical properties of the surf actant.
Moreover, du e to th e surface active properties of the ap plied catalyst complex,
the dynamic equilibrium b etween active and inactive catalyst spec ies can be
shifted, leading to an increased amount of active catalyst species at high er
surfactant concentrations and thus, to a higher catalyt ic activi ty. Based on th e
mechanism for catalysis in th e microemulsion system, a kinetic model was
derived u sing a parameter estimation from experimental data . The adapted
kinetic model includes th e impact of the surfactant a nd the local catalyst
concentration at the interface.
Finally, the lab-scale results were successf ully tran s ferred to a miniplant,
operated continuously over a period of 150 h with a stable phase separation (see
Figure 9). The correspond ing results are shown in PAPER 3 . A stable ald eh yde
yield of 21% was achieved and a stabl e p hase separati on was m aintained by
exact temperature co ntrol of the decanter during the whole operation time,
which enables quan titative catalyst recycling and product separation . The loss
of rhodiu m into the product phase was below 0.1 pp m, which is in accordance

Results and Discussion
28

with previou s lab findings. These results show th e applicability of microemulsion
systems for continuou s ly operated, catalytic reac tions on a larger scale.

Figure 9. Miniplant operatio n results for the hydrofor mylation of 1-dodecene ( PAPER 3 ). Case
1: continuous ope ration, τ Re actor = 0 .5 h, recycle ratio (oil:mix:wa ter) = 0.19 :0.57 :0.24, Ca se 2 : full
recycle, τ Reac tor = 3.2 h, recycle ratio (oil:m ix:water) = 0. 40:0.20 :0.40, Case 3: continous operation,
τ Reactor = 2.8 h, recycle ratio (oil:mix:wate r) = 0.40 :0.28:0.32 , Case 4 : continous operation, τ Reactor =
2.8 h, recyc le ratio (oil:mix: water) = 0 .24:0.52 :0.24.
Not only microemulsion systems have been investigated for th e
hydroformylati o n o f 1-dodecene bu t also the applicab ility o f surfactant-f ree
multiphase systems was tested, whi ch is show n in PAPER 4 . Ordinary aqueous-
organic biphasic systems suf fer from the low solub ility of th e substrate in the
aqueous catalyst phase, leading to very low catalytic activity. An easy way to
avoid the limitation s by the solubility is t he use of co-solvents, which enhan ces
the reaction rate d ue to the h igher solubility of th e substrate in the catalyst
phase. Hence, d iethylene glycol buty l ether, a short chain amphiphile as co-
solvent, h as b een investigated for the h ydroformylation reaction, leading to a
good reac tion performance an d enabling subsequent catalyst recycl ing by phase
separation.
4.1.2 Silylene Ligan ds as Alterna tives
Besides the development of sustainable reaction media for metal-catalyzed
reactions, the design and syn thesis of new ligands are in focus of current
research. The specific d esign of novel l igands offers the opp or tunity of an
enhanced catalytic activi ty and improved selectivity, covering the challenges of
Green Chemistry. In this context, the catalytic properties of monodentate and

Results and Discussion
29

bidentate NHSi ligands h ave b een in vestigated in h ydroformylation reaction for
the first time (PAPER 6) . Due to the spe cial electronic properties of NHSi
ligands, particularly t he enhanced σ- donor/π-acceptor properties, these new
class of ligands is a promising substitute for commercially available ligands.
Unexpectedly, the hydroformylation of styrene with [HRh(CO)(PPh 3 ) 3 ] and a n
excess of the monodentat e NHSi ligands [{PhC(N
t
Bu) 2 }SiNMe 2 ] and
[{C 2 H 2 (N
t
Bu) 2 }Si:] sho w a lower catalytic activi ty to th e ald ehyde product
compared to the benchmark system [HR h(CO)(PPh 3 ) 3 ] with or withou t an
excess of TPP. NMR studies reveal trisubstituted coordination of th e NHS i
ligands to th e rhod ium center, with or with out an excess of N HSi li gand.
However, th e strong dati ve S i-Rh bond h inde rs th e decoordin ation of th e ligand
to form the active 16-valence-elec tron rhodium com plex, hampering th e styrene
coordination, resulting in low catalytic activi ty.
In contrast, a ferrocenediyl based bidentate NHSi , used as the li gand in
hydroformylati o n reaction, enhances signif icantly the catalytic activity
compared to benchmark phosphines DPPF a nd XantPhos (see Table 1). Due to
the strong σ-don or ability of th e bis-NHSi, the formed [HRh(CO)(PPh 3 )(κ 2 -L 2 )]
complex, evid enced by NMR experiments, facilitates the dissociation of the
remained TPP and stabili zes the active 16-valence-electron complex.
Furthermore, the abil ity of th e NHS i ligand to act as π-acceptor promotes the
hydride migration ste p, accelerating th e reaction rate. As a resu lt, higher
conversions and TOFs are achieved.
Table 1. Conversion, l:b ratio and TOF of the hy droformylation with [HRh (CO)(PPh 3 )L 2 ]
complexes c ontaining biden tate liga nds L 2 at different tempe ratures (adap ted from PAPER 6 ). a
Entry Ligand L 2 Temperatu re T [°C] Conversion X b,c [%]

l:b b,c TOF b [h -1 ]
1 DPPF 50 traces - 3
2 XantPhos 50 2.2 43:5 7 32
3 Bis-NHSi 50 10.2 16:84 8 3
4 DPPF 80 3.9 34:6 6 91
5 XantPhos 80 29.4 47:53 646
6 Bis-NHSi 80 98.9 12:88 26 21
7 DPPF 100 12.5 35:65 589
8 XantPhos 100 56.4 49:51 30 07
9 Bis-NHSi 100 99.7 25:75 90 75
a Experimental conditions : 4 0 g toluene as solvent, n styrene = 38 mmol, p = 30 bar,
n [HRh(CO)(PPh3)3] = 0 .01 mmol, n ligand = 3 eq., stirrer speed = 1200 rpm.
b Determined by GC -FID.
c Determined at 5 0 °C after 240 min., at 80 °C after 12 0 min and a t 100 °C after 60 min. by GC-
FID.

Results and Discussion
30

Moreover, DFT calculation s were d one to confirm the diff ere nces in the
catalytic activity of the bis-NHSi and XantPhos ligand, showing a lower
activation barrier of the rate determin ing hydri de migration step for the bis-
NHSi li gand. The relativ e activation b arrier betwee n the phosph ine and th e bis-
NHSi is 0.7 kcal/mol for the linear product and 1.7 kcal/mol for the branched
produ ct, lead ing to the enhanced reaction rate for the silylene ligan d. Due to the
enhanced catalytic activity of NHS i, this n e w class of ligands can be seen as
green alternati ves to commercially available ligands based on nitrogen or
phosphorus.
4.2 Methoxycarbon ylatio n in Microemul sion Systems
After succes sful implementati on of microemulsion systems f or the
hydroformylati o n of 1-dodecene, the developed concept is to b e transferred to
another catalytic reaction. For this purpose, the p alla dium-catalyzed
methoxycarbonylation is investigated to validat e the p revio us findings and to
extend th e methodical toolb ox for catalysis in microemulsion systems.
Furthermore, the spectrum of raw materials is expanded to find a general
approach. Compared to the hyd roformylation reaction, th e f ormation of the
reaction mixture for the methoxycarbon ylation is more challenging, whi ch is
illu strated i n Figure 10.

Figure 10 . Schematic co mpariso n between the hyd roformylation a nd metho xyca rbonylation
reaction.
On th e one hand, a second liqu id substrate ( B ) is invol ved in the reaction,
which is an additional amphiphilic compon ent, af fecting strongly the p hase
behavior o f the microemulsion system. On the other h and, an acidic co-catalyst
is requi red to form the active p alladium-hydride complex. The unknown imp act
of the acid and the addit ional amphiphilic component on the catalysis and phase
separation of the microemulsion system makes the methoxycarbonylation more
complex. Furth erm ore, the f ormed ester ( D ) is surface active it se lf and b eha ves
like a surfactant, which complicates the p roduct separation. In order to valid ate
the feasibility of mic roemulsion systems f or the methoxycarbonyl ation, the
phase separation behavior and the reaction performance was considered.

Results and Discussion
31

4.2.1 Impact of M ethanol on the Phase B eha vior
Initially, t he impact of th e ad ditional amphiphilic reactant methan ol on the
phase behavior has be en investigated, w hich is depicted i n Figure 11. Base d on
the experiences from th e hydroformylation reac tion, Marlipal 24/70 as the
surfactant was chosen as the benchmark. The vari ation of the methanol amount
is expressed as the mol ar ratio with respect to the molar amount of 1-dodecene,
whereby the oil content α was f ixed at 50%. Furthermore, the investigati ons
were d one without any catalyst components to exclude the impact of these
additives on the phase behavior.

Figure 11 . Phase boundarie s for the microemulsion sy stem co nsisting of water, 1-dodecene and
Marlipal 24/70 with diff erent amounts of MeOH. Experimental conditions: m 1-dod ecene =12 g ,
m water =12 g, 1wt% Na 2 SO 4 , Marlipal 2 4/70 as surfactant.
In general, alth o ugh methan ol was ad ded to th e microemulsion system, the
phase separation is still f ast and complete in the th ree- phase region of th e
microemulsion system. However, the ph ase boun daries are signi ficantly shifted,
even with the addition of small amounts of methan ol, which can be summarized
in three p oints. First, with an in creasing amount of methanol in th e
microemulsion system, the three-phase region shifts to h igher temperatures.
Second, the min imal surf actant concentrati on   shifts to higher surfactant
concentrations with increasing amount of methanol. Third, the temperature
range for th e th ree- phase region of the microemulsion syste m enlarges. As

Results and Discussion
32

expected, methanol ac ts as a co-solvent and not as a co-surfactant, expl aining
the shif t of the three-phase region to higher temperatures. Since methanol is a
co-solvent, dissolved in the water ph ase, the water ph ase becomes more
hydrophobic and thus, th e surfactant inverts its solub ility now at higher
temperatures. All in all, despite the addition of methanol, the sensitive phase
separation of the microemulsion system is fe asible, whi ch is a b asic requirement
for catalysis in microemulsion systems with subsequent catalyst recycling .
4.2.2 Impact of Methanol on the Reaction P erforman ce
Not only the impact o f methanol on the ph a se behavior but also the impact of
methanol on th e reaction performance has been in vestigated to examine th e
feasibility of micr oemulsion systems for the p alladium-catalyzed
methoxycarbonylation. Hence, the methoxycarbon ylation was carried out in t he
benchmark microemulsion system, u sing Marl ipal 24/70 as the surf actant,
varying the methanol amount. Preliminary in vestigations revealed th at th e
composition of th e catalytic system is essenti al to ensure catalyst s tability and
reaction progress. Thu s, th e ratio of the pall adium precursor to th e water-
soluble li gand to co-catalyst (Pd:SX:MSA) was fix ed to 1:4:40 in the following
experiments. As expected, th e yi eld of the correspon ding ester methyl
tridecanoate in crease s with increasing amount of methanol in the microe mulsion
system, a s seen in Fi gure 12. The l: b regio selectivity remains ne arly constant
around 86:14. However, the correspondin g carboxyli c acid is also f ormed in
significant amoun ts as high -value side produ ct b ecause of th e av ailability of
water in the microemulsion system. Furthermore, the hydrogenation product is
also p roduced with low yields (Y Dodecane <5%), caused by the formation of
hydrogen in a water-gas shif t reaction. The carboxy lic acid is located in th e
nonp o lar ph ase , containing currentl y the ester, the carboxylic acid, dodecane,
and un consumed 1-dodecene, making further steps necessary to purify the
nonp o lar phase in order to ob tain th e ester as the final product. Ind eed, the
ester to acid ratio can be in crease d to 2 .3 b y in creasing the methanol to
substrate ratio to 2. However, a f urther increase of the methanol amount
hampers the ph ase separation after the reaction, making catalyst recycling
impossible. The impact of temperature and amount of co-catalyst on th e ratio of
the formed ester and carboxylic acid was also investigated but h as only a minor
impact. As a result, a microemulsion system is inap propriate ly f or the
methoxycarbonylation reaction. First, th e formation of the carboxyli c acid as
side p roduct cannot be avoided, complicat ing the purification of the crude
produ ct mixture. Second, the atom economy of the reaction is reduced, whi ch is
not in the sense of Green Chemistry.
In contrast, if the carboxylic acid is th e desired fin al product, microemulsion
systems are promising systems and a yield of 16% af ter 20 h reaction ti me can

Results and Discussion
33

be achieved. It is worth mentioning that no hydroxycarbonylation reac tion can
be observed in aqueous biphasic catalysis without surfactant. Hence, the
methoxycarbonylation and h ydroxycarbonylation are separably investigated in
the following sections.

Figure 12 . Yield o f trideca noic acid, dodeca ne and methyl tridecan oate for the
methoxyca rbonylation in microe mulsion syste ms. Experimental condi tions: T=11 0°C,
p CO =30 bar, m 1- dodecene =12 g, m water =12 g, n Pd(OAc)2 =0.16 mmol, Pd:S X:MSA=1 :4:40, 1 wt%
Na 2 SO 4 , n=120 0 rpm, t=20 h, γ=9%, Marlipal 24/7 0 as surfactant.
4.3 Methoxycarbon ylatio n in Biphasic Sys tems
In order to avoid the formation of th e acid, the methoxy carbonylati on h as been
carried out in an ordinary biphasic system, investigatin g the catalytic
performance and separation b ehavior. In this section, the path toward a
continuous process for th e methoxycarbonylation of 1-dodecene in miniplant
scale is shown, including the solvent selection in lab scale to optimize the
catalyst recycling, the variation of the reaction conditions in lab experiments
(temperature, p res sure) to d efine an operation window for the miniplant and
finally th e proof of co ncept in th e miniplant with continuous catalyst recycling
and product separation. Furth erm ore, th e impact of the applied sub strate has
been in vestigated to fi nd an appropriate biphasic system f or dif ferent substrates,
enabling the consecutive catalyst recycling and product separation.

Results and Discussion
34

4.3.1 Solvent Selec tion
In the sense of Green Chemistry, a solventless system is the best option to
perform metal-catalyzed organi c transformations, which can be ad apted to
multiphase catalysis for catalyst recycling via phase separation. For th e
methoxycarbonylation of 1-dodecene, the simplest b iphasic mixture is composed
of methanol as p olar ph ase and the substrate 1-dodecene as nonpolar phase,
using n o a dditional solvent. The catalyst can be immobi l ized in the methanol
phase due to the water -soluble li gand SX. The experimental results for th e
solventless, b iphasic methoxycarbon ylatio n are shown in PAPER 7 . It was
found th at the methoxycarbonylation can be p erformed without any additives.
The vari ation o f the catalyst concentration showed th at the TOF remains
constant around 80 h -1 , indicating a first-order depende nce on the reaction rate.
In contrast, the initial concentration of the cataly st is crucial for the recycling of
the catalyst complex after the reaction. At low pall adium concentrati o ns, no
recycling is possible via phase separation because of the formati on of a one
phase system after th e reaction. The more hyd ro philic ester, which is formed
during th e reaction, can solubilize th e catalyst containing methanol p hase,
inhibitin g catalyst recycling. However, phase separation tak es p lace at h igh
palladiu m concentrations, whereas th e leach ing of palladium and phosphorus
into the nonpolar phase is 4.6 p pm an d 45.7 ppm, respectively (see Tabl e 2,
entry 10). Thu s, the percentage loss of pallad ium is 0.5%, whi ch is too h igh
und er consideration of ecological an d economic factors. Add itionally, the imp act
of additional solvent s on the reaction performance and separation p roperties has
been investigated in PAPER 7 to optimize catalyst recycling. It was f ound that
modifications of both, the polar and nonpolar ph ase, lead to a drastic
improvement of catalyst rec yclin g.
First, it turned out that th e ad dition o f water is an easy approach to reduce the
leaching of the catalyst in to th e organic product p hase, as s een in Table 2. The
palladiu m leaching could be d rastically reduce d by the addition of 15 wt% water
to the p o lar phase from 4.6 ppm without water as a promoter (Table 2, entry
10) to 0.5 ppm (Table 2, entry 13). Moreover, the phosphorus loss could be
diminished to on e fiftieth adding 15 wt% of water. It is mentionab le that the
mass of the polar phase, which is th e sum of methanol and water, was constant.
The reaction mixture after t he reaction (Table 2, entry 12) is exemplarily shown
in Figure 13, in which a clear produ ct ph ase is formed, indicating almost no
catalyst leachin g. In addition, the modi fication of the polar methanol phase by
adding water increases slightly the ester amount in the n o npolar phase, resulting
in quan titative separation of the produ ct. The results prove th at the add ition of
water increases the polarity of th e polar me thanol p hase, leading to an improved
produ ct d istribution and a decreased catalyst leaching.

Results and Discussion
35

Table 2 . Met hoxycarbonyl ation of 1-dode cene: Modif ication of the pola r phase (adapted from
PAPER 7 ). a
Entry

water in
polar phase
[wt%]
Yield
(Ester) b [%]

TOF c
[h -1 ] l:b b Pd
leaching d
[ppm]
P
leaching d
[ppm]
product in
nonpolar phase b
[%]
10 0 97.6 63 67:3 3

4.6 45.7 94.7
11 5 95.1 47 68:3 2

1.0 4.4 96.1
12 10 93.6 31 70:3 0

0.8 1.7 98.7
13 15 84.6 29 69:3 1

0.5 0.9 99.0
14 20 44.5 14 72:2 8

0.1 0.3 99.4
15 50 0.9 - 80:2 0

0.1 0.9 99.8
a Experimental co nditions: Pd(OAc) 2 (0.16 mmol), Pd:SX:MS A:1-dodecene (1:4:40:44 5), pola r
phase (methanol a nd wate r) = 12 g, nonpo lar phase (1-dode cene) = 1 2 g, p(CO) = 3 0 bar,
T = 8 0 °C, t = 20 h, n =1200 rpm, phase separation a t room temperature.
b Determined by GC.
c Determined by g as co nsumption at a c onversion of 20%.
d Determined by IC P-OES.
However, the mod i fication of t he polar phase with water has a negat ive eff ect o n
the reaction performance. The addition of water to the biph asic mi xture showed
that the TOF d ecreas es signif ica ntly from 63 h -1 to 14 h -1 using 20 w t% water in
the polar phase. Assuming a kinetically con trolled biphasic reac tion, which was
also shown in PAPER 7 by vari a tion of the stirrer speed havin g n o in fluence on
the reaction rate, th e rate of m ethoxycarbonyl at ion can be li mited by the
concentrations of the reac tants 1-dodecene, carbon monoxide, and methanol in
the catalyst phase. It was fou nd that the pressure of carbon monoxid e has no
impact on the reaction rate ( PAPER 10 ). However, th e solubility of 1-dod ecene
is decreased b y adding water to the polar p hase, which could lead to lower
reaction rates. On th e other hand, the concentration of methanol is also reduced
by adding water to th e polar phase, which could result in the ob se rved
reduction o f reac tion rate, indicating th e methanoly sis as th e RDS of th e
methoxycarbonylation. Interestingly , the experime ntal results rev ealed th at th e
addition of water for recycling optimization does not lead to the f ormation of
significant amounts of the carboxy l ic acid as a side produ ct. T he yield of th e
acid does not exceed 1.8% for the in vestigated reac tion mixtures, meanin g th at
the hydrolysis-equilibrium is fully shifted to the side of the ester and the ester to
acid ratio is ab ove 50. Hence , th e b iphasic me thoxycarbon ylatio n of 1-dodecene
outperforms clearly t he methoxycarbonylation in microe mulsion syste ms, i n
which the ester to acid ratio is at most 2.3.
Second, it was found that the modi fication of th e nonpolar phase by adding
alkanes as co-solvents is a p romising tool to redu ce catalyst leach ing into the

Results and Discussion
36

produ ct p hase. Compared to the system with out co-solvent, the leaching of
palladiu m and phosphorus can be decr eased to 0.5 ppm and 2.3 ppm,
respectively, using octane as co-solvent. The type of alkane as co-solvent showed
no impact on the leaching and reaction performance .

Figure 13 . Reaction mixtu re a fter phase separation a t roo m temperatu re (sepa ra tion time of
10 min) for the des cribed e xperiment in Ta ble 2, entry 12 (PAP ER 7) .
As shown, good leachin g results could be obtai ned usi ng at least 10 wt% water
in th e polar phase. T o in vestigate th e impact of d ifferent substrates on the
reaction performance and ph ase separation behavior of the
methoxycarbonylation, a biph asic system with 10 wt% water in the polar
methanol phase was used as a b enchmark. Add itionally, octane as co-solvent
was added to avoid rigorous shifts because of the f ormation of the corresponding
produ ct, makin g the res ults better comparable. The corresponding results are
shown in Table 3. Furth ermore, preliminary investigations s howed th a t
solventless b iphasic systems are n ot f easible for the methoxycarbonyl at ion of
styrene, methyl 10-undec enoate, and 1-octene, since n o p hase se paration occurs
after the reaction at room temperature, preventing subseque nt catalyst
recycling. As expected, th e type of the substrate and its p olarity has a hu ge
impact on the reaction p erformance and the phase separation. C omparing the
linear α-olefins 1-dodecene an d 1-octene ( Table 3, entry 16 and 17), similar
yields an d l:b selectivities can b e achieved af ter a reaction time of 20 h.
However, th e TOF for 1-octene is signi ficantly higher th an the TOF of
1-dodecene, which can b e expl ained with two reasons. Firstly, the solubil ity of
1-octene in the polar catalyst phase is higher than that of 1-dodec ene, leadi ng to
a h igher concentration of 1-octene in th is phase and thu s, to an advanced

Results and Discussion
37

reaction rate. Secondly, the length of th e linear α-olefin has an impact on the
catalytic activity. Th e longer the hydrocarbon chain is, th e lower is the catalytic
activity, due to the hampered formation of th e p alladium-alkyl species.
Nevertheless, th e p hase separation p roceeds very fast after th e reaction, leading
to a polar catalyst phase an d n onpolar p r oduct phase. In both cases, the
leaching of palladium and phosphorus is under the detection li mit of ICP. Sli ght
differences can b e measured in the product distrib ution after phase separation,
97% of th e p ro duct is located in the n o npolar ph ase for the 1-dodecene
methoxycarbonylation and as expected, th e content of the more polar product
methyl nonanoate reaches only 89%.
Table 3. Methoxycarbonyla tion in biphasic sy stems: Substrate s cope. a
Entry

substrate Yield
(Ester) b
[%]
TOF c
[h -1 ] l:b b Pd
leaching d
[ppm]
P
leaching d
[ppm]
product in
nonpolar phase b
[%]
16 1-dodecene 91.7 9 68:3 2

- - 97.0
17 1-octene 93.1 15 68:3 2

- - 89.0
18 styrene 96.8 41 55:4 5

0.5 4.5 35 .4
19 methyl 10-
undecenoate

84.6 19 63:3 7

0.6 1.7 60 .4
20 cyc lohexene

44.5 12 - - - 63 .5
a Experimental condi tions: Pd( OA c) 2 (0.16 mmol), Pd:SX:MSA (1:4:4 0), p olar phas e:
methanol 1 0.8 g, water = 1 .8 g, nonpolar phase: substrate = 3 g, octane = 9 g,
p(CO) = 3 0 bar, T = 80 °C, t = 2 0 h, n =1200 rpm, phase separation at room temperat ure.
b Determined by GC.
c Determined by g as co nsumption at a c onversion of 20 %.
d Determined by IC P-OES.
Similar trends can b e observed f or the oth e r in vestigated substrates (Table 3,
entries 18-20). The higher the polarity of the substrate, the higher is the
reaction rate but the lower is the content of the corresponding p ro duct in the
nonp o lar phase. For styrene methoxycarbon ylation, the content of the
corres pond ing product is very low with 35.4%. Hence, th e applied biph asi c
system is not suitable for styrene as th e substrate. However, the b iphasic system
can b e modified with th e addition of fu rt her co-solvents, eith er to the polar or
nonp o lar phase, imp ro ving th e catalyst recycling and p ro duct separation after
the reaction, which was shown in PAPER 7 for 1-dodecene.
In summary, the results reveal the f easibility of th e methoxycarbonyl ation of
different substrates in liquid/liquid biphasic systems. Considering the reaction
performance an d separation behavi or, the biphasic system has to b e select
carefully to meet the requirements of an ecological and economical b iphasic
reaction. Moreover, simple modifications of both , the p olar and nonpolar phase,

Results and Discussion
38

by adding co-solvents can lead to a significant optimization of catalyst recycling
and p roduct separation p ro perties. To transfer th e methoxycarbonylation of
1-dodecene to a contin uously op erated process, a b iphasic system was chos en
composed of 10 wt% water/methanol as the p olar ph ase an d octane/1-dodecene
in a mass ratio 3 :1 as th e no npolar phase. The mas s of the polar a nd nonpolar
phase is the same with 12 g. Furthermore, palladium acetate as th e precursor is
applied with a molar amoun t of 0.16 mmol, in which th e Pd:SX:MSA ratio was
kept constant with 1:4 :40, ensuring phase s eparation and catalyst s tabil i ty.
4.3.2 Parameter s tudies
For the tran sfer of the lab scale results to a miniplan t , not only a n ap propriate
biphasic system is crucial, but also suitable reaction conditions to ensure th e
long-term stabi lity of the catalytic system, g eneral ph ase separation , and good
reaction performance. Hence, th e temperatur e and pres sure have b een varied i n
lab scale experiments with special focus on the reac tion performance an d phase
separation b ehavior, which was investigated in PAPER 10 . The appli cability of
the phase separation was first investigated at room temperature. It was found
that b ot h, reaction pres sure and temperature, have no in fluence on the ph ase
separation properties, particularly on the dynamic of phase separation,
distribution of the p ro duct, and catalyst leachin g. Thus, the solvent se lection,
which was described i n the p revious section, d etermines th e qu ality of phase
separation. Consid ering th e d escribed b iphasic reaction mixture, the leachin g of
palladiu m and phosphorus is less th an 0.1 p pm and 1 ppm, respectively. As
expected, th e distribution of th e product in to the no npolar phase is rather h igh
and exceeds 95%, independent from the reaction condition s.
In contrast, the variation of the reaction conditions showed a hu g e impact on
the reaction performance. It was foun d that the methoxy carbonylation can
already be carried out at low carbon monoxi de pressure (5 bar) without loss in
catalytic activity. The experimental results hint that the methanolysis step is
rate d etermining, in w hich the palladium-acyl spec ies is the res ting state of the
catalytic cycle. Af ter 20 h reaction time at 5 bar carbon m onoxide, the
conversion of 1-do decene was 94.8%, in which a y ield to th e ester of 72.6% was
achieved. The l:b reg ioselectivity was 69:31, which was independent on the
carbon monox ide p ressure. However, th e investigations tu r ned out that th e
pressure of carbon monoxide af fects strongl y th e isomerization of 1-dod ecene.
The higher th e pressure, th e lower is the yield of dodecene isomers, in dicating a
suppression of isomerization at high carbon monoxide p res sure. As expected, the
variation of th e reaction temperature showed that the initial reaction rate
increases with higher temperatures (see Table 4). An Arrhenius behavi or was
observed up to 80 °C, indicating a kinetically controlled biphasic reaction, whic h
is in agreement with th e investigations in PAPER 7 . An activation energy of

Results and Discussion
39

203 KJ/mol could be c alculated. A further increase of th e reaction temperature
deviates from the Arrheni us behavior, which cann ot be attributed to mass
transfer li mitations since th e formation of palladiu m black could be ob se rved
above 80 °C. Thu s, th e conversion of 1-dodecene after 20 h reaction ti me
reaches a maximum of 94.8% at a reaction temperature of 80 °C. The in fluence
of temperature and catal yst concentration on catalyst stabi lity has been also
studied in PAPER 11 . Moreover, the experimental results revealed that the
isomerization of 1-dodece ne can b e suppressed at high temperatures, improving
significantly the chemoselectivity of th e methoxy carbo nylation up to 92% at
100 °C. The energetic barriers for th e methoxycarbonylation and isomerization
reaction are rath er dif ferent, leading to an increase of th e selectivi ty with higher
temperature. Meckin g et al. showed similar result s in DFT calculations for th e
isomerizing me thoxy carbonylation of me thyl heptenoat e, in which a higher
activation b arrier for the methoxycarbonylation was found compared to the
isomerization. 25
Table 4 . Methoxyca rbonylation of 1 -dodecene: Vari ation o f the tem perature (adapted f rom
PAPER 1 0 ). a
Entry

T
[°C] Co nversion b
[%]
Yield
(Ester) b
[%]
TOF c
[h -1 ] Sele ctivity b
[%] l:b b Product in
nonpolar phase b
[%]
21 60 13.9 1.7 0.1 12.2 73:2 7

95.2
22 70 38.1 12.5 0.7 32.8 71:2 9

97.4
23 80 94.8 72.6 6.4 76.6 69:3 1

97.7
24 d 90 85.8 72.4 11.3 84 .4 68:3 2

97.5
25 d 100 87 .2 80.2 17 .8 92.0 6 9:31

96.7
a Experimental conditions : Pd(OAc) 2 (0.16 mmol), Pd:SX:M SA (1:4 :40), pola r phase
(m methanol = 1 0.8 g, m water = 1 .2 g), nonpola r phas e (m 1-dod ecene = 3 g, m octane = 9 g),
p(CO) = 5 bar, t = 2 0 h, n =1,2 00 rpm, phase sepa ration at room temperatu re.
b Determined by GC.
c Determined by g as co nsumption at a c onversion of 10%.
d Pd black formation at the end of the reaction.

Based on these results, a temperature of 80 °C was chosen to transfer th e results
into th e continuously operated min iplant, ensuring lon g-term catalyst stabi lity
and good reaction p erf ormance. Moreover, th e pressure wa s s et to 5 bar carbon
monoxide despite enhanced isomerization at low p res sures. However,
isomerization can be suppressed b y an appropriate choice of the op erating
conditions in the miniplant, which is showed in the next section.

Results and Discussion
40

4.3.3 Proof of conc ept in a miniplant
The proof of concept for the biphasic methoxycarbonylation was done in a
miniplant, op erated conti nuously 100 h ( PAPER 10 ). S pecial attention was paid
on the imp act of the in ternal cycles and conce ntration shifts on th e reaction
performance and phase separation properties. Diff ere nt op eration modes (SP)
have b een applied during the continu o us p roce ss, in vestigating the imp act of
residence ti me and stirrer speed on bo th, the reaction performance and
separation results. Figure 14 shows the min i plant operation results for the
methoxycarbonylation of 1-dodecene with respect to th e reaction performance.
After inertization wi th nitrogen, all components were in troduced into the high-
pressure section of the miniplant, according to the masses described in section
4.3.1. Afterward, the recycle pumps of th e decanter were started, establishing
stable phase separation under full rec ycling cond itions. The reac tor was heated
to 80 °C and the nitrogen atmosphere was replaced b y 5 bar carbon monoxide,
marking the start of the rea ction at operation hour 0. The miniplant was
operated i n full recycle mode to operation ho ur 20 (SP 1) in order to reach the
first working point quickly. Despite the formation of more h ydro philic esters,
the phase separation could be initiate d at 25 °C in the decanter. A t the end of
SP 1, a yield to the esters of 54.9% an d a conversion of 1 -dodecene of 82% could
be obtained. Interestingly, it was found that the l:b regioselectivity in the
miniplant is constant around 82:1 8, which outperforms the findings in the lab
scale experiments. This fact could be explained by the observed ind uc tion period
in lab sc ale experiments (se e PAPER 7 and PAPER 10 ), w hich could b e
suppressed in the min iplant operation b ecause of appli ed catalyst cond itioning.
Thus, the active p alladium hy drid e spec ies is available i n sufficient amounts a t
operation hour 0, resulting in a h igher l:b regioselectivity and h igher in i tial
reaction rates in min iplant scale. However, it was shown in PAPER 10 that and
efficient catalyst preformation can b e adapted to lab scale, hampering th e
induction period of the methoxy carbo nylation. In SP 2, the continuous
operation was initiated by activating the 1-dodecene feed stream. The
continuous operation could be stabilized at leas t for 40 h o urs with only small
changes in the reaction performance because of th e d i lution of the reactor
content with fresh 1-dodecene and concentration shifts due to internal recycles ,
indicating steady state conditions at th e end of SP 2. Moreover, it was f oun d
that the reaction residence time has an impact on the chemoselectivi t y of t he
reaction. The lower th e res idence time, th e higher is th e chemoselectivity
because of the hampered isomerization, which was in vestigated in S P 3.1 and
3.2. It is important to consider that steady state conditions could not be
awaited due to lack of total operation time. Additionally, the st irrer spee d was
reduced in SP 3.2, increasing abruptl y the chemoselectivity of
methoxycarbonylation to 91%. It was show n th at the absence of th e catalyst

phase in the d ec anter d u e to th e redu ce d sti rrin g spee d leads to the in cre ase of

chemose l ec tivity .
Figure 14 . Mini
plant opera tion results for

PAPER 10 ). S P 1 :
Full r e cyc le

rate = 0
g/h, Stirrer Spee d = 1 3 0 0

ratio (nonpolar:pola r
) = 0 .

Continuous Ope ration, τ
R ea ct or

100
g/h, Stirrer Speed = 1 3 0 0

(nonpolar:pola r) = 1:0,
Fee d ra te = 1 0 0
Furthermore, it tu rne d ou t t h at th e phase se p aration i n th e d ec ante r could b e
maintain e d during t h e whol e o p eration ti me . First, t h e p al l ad iu m a nd
phosphorus leaching i n to th e n onpolar p rod u ct p h ase

250
ppb , respectively, conf irmin g t h e lab res u lt s. S ec on d, th e es ter content i n
the nonpolar product p h ase exce eds 99%, whi ch is also i n acc orda n ce with lab

findings.
In summary,
the fe asibi li t y of t h e p roce ss conce p t was sho wn f or
methoxycarbonylation of 1
simple b iphasic system .
reaction cond itions was p roven wit h
separation with low c atal
Moreover, it was sh own th at t h e ti me for makin g n ew p roc es s conce p ts
applicable in larger sc ale can b e d rasticall y redu ce d worki n g h a n d in h and wit h
constant interaction b etwe en

Resul t s an d D iscuss ion
p h ase in th e d ec an ter due to the redu ce d sti rring speed leads to the in cre ase of
plant o per ation results for

the methoxyca rbonylation of 1-
d ode ce ne
Full recycle

, τ Reactor = 0.51 h, recycle ratio (
nonpolar: p ola r
g / h, Stir re r Spe e d = 1 300

rpm, S P 2 : Con tinuous Operation, τ
R eac tor
) = 0.

5:0.5, Feed rate = 30
g/h, Stirrer Speed = 1 3 0 0
Reactor

= 0.45 h, recycle ratio (nonpola r:polar
) = 0 .
g / h, Stir re r Spee d = 1 300

rpm, SP 4 : Continuou s Operatio n, τ Reactor
= 0 .
Fe ed rate = 1 00

g/h, Stirrer S peed = 70 0 rpm.
Furth erm ore, it tu rne d out that th e phase separation in th e d ec ante r could b e
main tai n e d duri n g the whol e operation time. First, the p al l ad iu m a nd
p h osp h orus leachin g into th e nonpolar product ph ase

were
b elow 25
p p b , res p ec ti vely , conf irming the lab result s. S econd, th e es ter content i n
th e n o n p olar p ro d u ct p hase exceeds 99%, whi ch is also in acc orda n ce with lab
th e f easibility of the process concept was sho wn f or
me th oxy carbon y lat io n of 1

-dodecene
in a continuously operat e d mi n i
simple b i p h asic syste m.

The ap plicability of the ap plied biph asic mixt u re a n d
reac ti on cond i ti on s was proven with

long-
term catalyst stabi lity, phase
se p aration with low catal

yst leaching, and good
overall reac ti on p erformance .
Moreover, it was s hown th at the ti me for makin g new p roc es s conce p ts
ap p l icabl e i n larger s c ale can be d rastically redu ce d working h a n d in h and wit h
constant in terac ti on b etween

the lab and min i plan t o perators.

Resu lts and Discussion

41
p h ase in th e d ec an ter d u e to th e redu ce d sti rrin g spee d leads to the in crease of

dodecene

(taken fr om
nonpo la r: p olar

) = 0.5 :0.5, Feed
Reactor

= 0 .49 h, recycle
g / h, Stirrer Speed = 1 30 0

rpm, SP 3 :
) = 0.

5:0.5, Feed rate =
= 0.

45 h, recycle ratio
Furth erm ore, it tu rne d ou t t h at th e phase se p aration i n th e d ec anter could be
main tai n e d duri n g t h e whol e o p eration ti me . First, t h e palladium and
below 25

ppb and
p p b , res p ec ti vely , conf irmin g t h e lab res u lt s. S ec on d, th e ester content in
th e n o n p olar p ro d u ct p h ase exce eds 99%, whi ch is also i n ac cordance with lab
th e f e asibi li t y of t h e p roce ss conce p t wa s sho wn f or

the
in a con ti n u o u sly op erat ed mini

plant in a
The ap plicability o f t h e ap plied b i p hasic mixtu re and
term catalyst stability, phase
overall reac tion performance.
Moreover, it was shown th at t h e ti me for makin g n ew p roc ess concepts
ap p l icabl e i n larger sc ale can b e d rasticall y redu ce d worki n g ha nd in hand wit h

Results and Discussion
42

4.4 Hydroxycarbon ylation i n Microemul sion Systems
In contrast to the meth oxycarbonylation of 1-d odecene, a solventless biph asic
hydroxycarbonylation, in which water act as catalyst ph ase and 1-dodecene as
nonp o lar phase, cannot b e appli ed. Since the solubility of 1-d o decene is too low
in th e aqueous phase, n o reaction p rogress could b e observed. Indeed, p o lar
organic co-solvents such as acetonitrile or dimethylformamide can be used to
modify the p olarity of th e aqu eous phase, leading to an enhan ced solub ility of
1-dodecene and th us, to an overall better reaction p erformance. However, th e
use of these toxic solvents is incompatible with the requi rem ents of Green
Chemistry and should be avoided. A smart an d sustain a ble ap proach to
overcome limitati ons by the solvent less bip hasic syst em is th e use of surfactants
as ph ase tran sfer age nt f or the hydroxycarbon y lation of 1-dodecene, which is
described in this section. Moreover, the temperature-induced switchabil i ty of the
phase b ehavior can be u sed to separate the produ ct and recycle th e catalytic
system via ph ase separation . Special attention was paid to the catalyst behavior
in microemulsion systems ( PAPER 1 and PAPER 2 ) to recycle the catalyst
quantitatively. Furthermore, the hydroxy carbonylation of 1-dod ec ene h as been
studied in microemulsion systems to correlat e the phase b ehavior and reaction
performance ( PAPER 11 ).
4.4.1 Catalyst Behavio r in Micro emulsion Sy stems
Detailled knowledge of the catalyst d istribution in surfactant-based systems is
important for an efficient catalyst recycling as well as f or evaluating the
reaction performance. In contrast to ordi nary biphasic systems, microstructures
are formed in systems with a surf acta nt as phase tran sfer agent, affecting
strongly the catalyst distribution in such a system. Hence, th e impact of the
type of li gand, the type of surfactant, and the temperature on th e d istribution
of th e catalyst complex has b een systematically investigated. Special focus was
set on th e water-soluble li gands TPPTS and SX and the nonionic surfactants to
exclude ionic interaction between t he surfactant and li gand. I nitially, the effect
of the ligands on the distrib ution in aqueous micellar solut ions h as been stud ied
to avoid in teractions with the corresponding oil phase and the f or mation of the
entire catalyst complex. As expect ed, it was f ound in PAPER 2 th at th e
hydrophobic li ga nds TPP and XantPhos show similar partition coefficients in
water/octanol and aqueous micellar solution s. In contrast, th e water-soluble
analogs TPPTS and SX exhibit a completely different b ehavior in both systems .
On th e one hand, the logarithm of the partition coefficient is low in
water/octanol for b oth ligan ds, indi cating the solubil ity of these ligand s in the
water ph ase. On th e oth er hand, a high partition coefficient was ob tained in
aqueous micellar sol ution s, leading to the conclusion th at the ligand is
incorporated in to th e micellar microstructure. It turned out th a t the surface

Results and Discussion
43

active properties, which were determined in investigati ons of the surface tension,
lead to the in clusion of the water-soluble li gands in the micelle. Furth ermore, a
minor impact of th e hyd rophobicity of the surfactant was fou nd with respect to
the partit ion coefficient, in whi ch a more hydrophilic surfactant increas es the
micelle-water p artition coefficient. Besides t he p olarity of the ligan d, further
effects have to be considered to p redict the partition coefficients in aqueous
micellar solut ions, particularly the surface active properties of the ligand and
molecular interactions between ligand and surfactant.
However, to perform organi c tran sformations in surfactant-based systems , these
basic findings h ave to be extended to th e enti re catalys t complexes.
Furthermore, th e impact of the addit ional organic phase contai ning the
substrate has to b e considered. Hence, the distribution of catal yst com plexes in
microemulsion systems h as been investigated in PAPER 1 , in which rhodiu m as
the metal center was chosen. In general, the same b ehavior could be ob se rved
for the en tire cataly st complex compared to the sole li gand. Using the
hydrophobic ligands TPP and XantPhos in microemulsion systems composed of
water, 1-dodecene, and Marlipal 24/70 as the surf actant, most o f the rhodium
complex is located in the oil excess phase of the triphasic microemulsion system.
In contrast, it was f ound that th e rhodium complexes formed with TPPTS and
SX are located in the surfactant-rich phase to a larger extent. Interestingly,
using SX as the li gand, 96.3% of th e catalyst complex are in th e bicont inuous
middle phase of th e microemulsion system, whi ch is due to the surface active
properties of the ligand. It was conclud ed that the ligand determines the surface
active properties of the whol e catalyst complex an d thus, the catalyst complex
behaves like a surfactant, accumulating in the middle phase of the
microemulsion system. Investigations on the surface tension of th e whole
catalyst complex confirm this observation. Moreover, th e distribut ion of the S X-
modified rhodium complex in the different phase regions has b ee n stud ied. As
expected, it was found that in the 2Φ region, 99.99% of the cataly st is located in
the microemulsion phase, whereas in th e 2
 Φ region the catalyst is in b oth
phases equal ly distributed. However, n ot only the catalyst distribution but also
the phase separation dyn amics has to be considered for the application of
microemulsion systems with subsequent catalyst recycling. Thu s, the ti me f or
phase separation in the d ifferent ph ase regions of the microemulsion system h as
been in vestigated in PAPER 1 . It turned out th at the th ree-phase region of the
microemulsion system is of great interest for the application of metal-catalyzed
reactions in microemulsion systems. First, th e time for p hase separati on can be
decreased, enabling a smaller decanter in a continuou s p roce ss. S econd, th e oil
and water excess phase allows separation of hyd ro phobic and hydrophilic side
and mai n products. Changing th e catalytic system from rhod ium-SX to
palladiu m- SX, the same catalyst b ehavior in microemulsion systems could b e

Results and Discussion
44

observed, whi ch is depicted in Figu re 15. Due to the surface active properties of
the catalyst complex, it is like a surfactant and follows the surfactant into the
corres pond ing phase.

Figure 15 . Schematic pictures o f the oil-in- water microemulsion, triphasic system and water-in-
oil microemulsio n for t he pa lladium-catalyzed hydroxy carbonylation of 1 -dodecen e (taken f rom
PAPER 1 1 ). Test conditio ns: T=8 5 °C, α=0.5, 1 wt% Na 2 S O 4 , Pd 2 (allyl) 2 C l 2 (0.02 mmol),
Pd:SX:MSA:1- dodecene=1:4 :40:110, mas s ratio 1-dodecene to dode cane=1:3 , Marlipal 24 /50 as
the surfactan t, γ=4% (left), γ=9% (middle) , γ=14% (ri ght).
4.4.2 Nonionic Surf actants as P hase Tra nsfer Ag ent
Besides th e catalyst b ehavior, the phase behavi or of microemulsion systems
plays a crucial role to evalu ate the reaction performance in these systems an d to
ensure catalyst rec ycling via ph ase separation. Particularly, th e interaction
between phase b ehavior and reaction performance is of great in terest to identi fy
crucial operatio n parame ters such as surfactant concentrati on, the
hydrophobicity of the surf actant, and react ion temperature, whi c h h as been
investigated in PAPER 11 . Figu re 16 s hows th e ph ase diagram of the
microemulsion system composed of 1-dodecene/dodecane as the nonpolar phase,
water and th e surfactant Marlip al 24/50. It is imp or tant to notice th at all
reaction components such as catalyst precursor, ligand, a nd co-catalyst were
added to scree n the ph ase behavior, since th eir addition can lead to a
remarkable shift in t he phase boundaries. For instance, it was found in
PAPER 1 that the addition of S X as the ligand can lead to a switch of the
phase boundaries up to 10 K, dependent on th e SX amou nt. Investigation s on
the phase behavior were li mited to temperatures up to 90 °C, since the

Results and Discussion
45

formation of p alladium black was observed at higher temperatures. It tu rned
out in PAPER 11 that the investigated microemulsion system can be
characterized with a minimal surfactant concentration   of 14% with a
corres pond ing temperature 
 of 61 °C. Investigation s on the phase behavi or are
the basis to f ind a suitab le operation window for the subsequent catalyst
recycling and should be considered for an efficient selection of the surfactan t.

Figure 16 . Phase diagram of a mixture of 1- dodecene, dode cane, water, a nd Ma rlipal (24/ 50)
(taken and modi fied from PAPER 11 ). Tes t conditi ons: α =0.5, 1 wt% Na 2 SO 4 , Pd 2 (allyl ) 2 Cl 2
(0.02 mmol), Pd:SX:MSA:1 -dodecene= 1:4:40 :110, mass ratio 1 -dodecene to dodecane=1:3.
With the phase behavior of the microemulsion system in mind, the impact of
surfactant concentration, reaction temperat ure, type of surf acta nt, organic
co-solvents an d catalyst concentration on the reaction performance h as been
systematically studied in PAPER 11 . It was found that th e
hydroxycarbonylation of 1-dod ecene in microemulsion systems is a kin etically
controlled multiphase reaction, indicated by a typical Arrhenius type b ehavior
at mild reaction temperatures. However, increasing th e temperature above 90 °C
leads to a significant loss of catalytic activi ty due to th e formation of p alladium
black which is similar to the methoxycarbonyl at ion of 1-dodecene in b iphasic
mixtures (see PAPER 10 ). Variation of the surfactant concentration shows th at
the catalyt ic activity, indicated by the yield of linear acid and conversion of
1-dodecene, increases with higher amounts of surfactant (see Figure 17). As

Results and Discussion
46

expected, a minimal s urfactant concentrati o n ( γ>3%) is necessary to accelerate
significantly t he rate of hyd roxycarbonyla tion, marked b y the surfactant
concentration   , which is needed to form a microemulsion.

Figure 17 . Effect of the surfactant concent ration o n the hydroxy carbonylation of 1 -dodecene
(taken from PA PER 11 ). Experimen tal co nditions: Pd 2 (allyl) 2 Cl 2 (0.0 8 mmol), Pd:SX:MS A:1-
dodecene=1 :4:40:1 10, α =0.5, dode cane as the co-so lvent (9 g), wate r (12 g), Marlipal 24/5 0 as
the surfactan t, Na 2 SO 4 (1 wt%), p (CO)=30 bar, T=85 °C, n=120 0 rp m, t=20 h.
Interestingly, the p has e behavi or changes f ro m an oil -in-water microemulsion to
a trip hasic system at a surfactant concentration of γ=7% and f inally to a water-
in-oil microemulsion at γ=11%. However, t he yield and conversion in crease
steadily, indicating n o impact of the ph ase behavior on the reaction
performance. Further investigation s wit h modification of the nonpolar phase and
the variation of the degree of ethox ylation confirm that the reaction
performance does not care about the phase behavi or of the microemulsion
system. Fro m th ese r esults, it could b e conclu ded how catalysis, espec ially
metal-catalyzed transformations, works in microemulsion systems. S ince the
applied water-solub l e catalyst complex is surface active, the
hydroxycarbonylation tak es mainly place at the interface b etwe en th e oil and
water. Thu s, the local concentration s of the reac tants at th e oil-water interface,
includin g the concentrati on of the active cataly st complex, and the size of th e
interface are crucial for th e reac tion performance. Hence, it was found that
amount and hyd ro philicity of the surf acta nt should be consid ere d as the main
parameters influ enci ng the reaction p erfor mance. First, the amoun t of the

Results and Discussion
47

surfactant provides the size of the in terfacial area, aff ecting strongl y the
reaction performance. The higher th e amount of surf acta nt, th e h igher is the
interfacial area, th e better is the catalytic activity. However, the in terfacial area
can only b e in cre ased to a maximu m at whi ch f urther effects like viscosity have
to be considered. S econd, the typ e of surfactant, particularly the degree of
ethoxylation, is crucial for the reaction p erfo rmance. The hydrophilicity of the
surfactant determines the local conce ntrations of the reac tants at the in terface.
Thus, an accumulation of the reactants at th e interface by the choice of an
appropriate surfactant enh ances the reaction performance in microemulsion
systems . These f indings are in agreeme nt with PA PER 8 , in which the role of
nonionic surf actants for the rhod ium catalyzed hyd roformylation h as b ee n
investigated. Here, the amoun t and ty pe of surf actant are also of utmost
importance for the catalytic activity in microemulsion systems.
4.4.3 Ionic Surfac tants as Phas e Transfer Ag en t
Additionally, ionic surfactants as phase tran sfer agents h ave been in vestigated
for the p a lladium-catalyzed hydroxy carbo nylation of 1-dodecene. Here, ion ic
interactions b etween the catalyst complex and the surf acta nt h ave to be
considered to evalu ate the r eaction performance and separation behavior.
Initially, the ionic surfactants S DS and CT AB were test ed as a b enchmark,
which is shown in Table 5.
Table 5. Hydroxycarbonyla tion of 1 -dodecene: Io nic surfactants as phase transfe r agents. a
Entry

Surfactant

Surfactant
concentration
γ [%]
Conversio n b
[%] Yie ld (Acid) b
[%] TOF c
[h -1 ] l:b b Phase
separation

26 SDS 2 <1 0 0 / No
27 CTAB 2 27.3 19.9 33.1 90:10

No
28 CTAB 1 20.7 15.8 24.0 89:11

No
29 CTAB 0.5 10.1 7.9 4.7 8 8:12

No
30 CTAB 0.2 2.3 1.6 0.9 84:1 6

Yes
a Experimental condi tions: Pd(OAc) 2 (0.05 mmol), Pd:SX:MSA (1:4 :120 ), m water = 12 g ,
m 1-dodecene = 1 2 g, p(CO) = 30 bar, T = 80 °C, t = 6 h, n =1200 rpm, phas e sepa ration at roo m
temperature.
b Determined by GC.
c Determined by G C after 1 h reaction time.

Clear dif ferences are visible comparing th e cation ic CTAB an d an ionic SDS
(Table 5, entries 26 and 27) at a fixed surf act ant concentrati o n (γ=2%). A TOF
of 33.1 h -1 an d a yield to th e carboxylic acid of 19.9% could be achieved with
CTAB as the phase transfer agent, whereas no reaction takes place u sing the
anionic S DS . The ligand SX is used to make the catalyst water- soluble, resulting

Results and Discussion
48

in a n egatively charged catalyst complex. Thu s, repulsiv e interaction between
the anionic SDS and a nionic catalyst complex occurs, hindering the catalyst to
come to th e oil -water interface. Since the h ydroxycarbonylation mainly tak es
place at the oil -water interface, the reaction is hampered. In contrast, an
attractive interaction between the surfactant an d catalyst complex results using
CTAB as th e surfactant. Hence, th e catalyst is strongl y attached to the
interface and the reaction tak es place. However, ph ase separation is n ot
possible, since a stabl e emulsion is f ormed after th e reaction. Decreasing the
amount of CTAB leads to a redu ction of the catalytic activity from 33.1 h -1 at
γ=2% to 0.9 h -1 with a surfactant concentrati on of γ =0.2% (Table 5, entries 27-
30). Here, th e interface between the oil and water is d ecrease d, whi ch leads to a
retardation of the reaction rate. Nevertheless, the phase separation is possible
using γ=0.2%.
Promising res ults wit h respect to reaction pe rformance and separation behavior
were obtain ed with other cationic p hase transfer agents. The io nic liquid 1-
Methyl-3-octyli mi dazolium bromide (OMIM) outp erforms clearly the cationic
benchmark CTAB, leadin g to a h ig h catalyt ic activi ty and quantitative catalyst
recycling after the reaction (see Tabl e 6, entry 31). To understand the role of
the ionic liquid, actin g as a cationic surfactant in t his case, the ionic liquids of
the homolog series have been in vestigated using a constant concentration of th e
phase transfer agent (0.5 M) and th e fivefold CMC (see Table 6). It is
mentionable that the concentrati on is expressed as moles of the ionic liquid in
the water ph ase. Additionally, the CMC was measured with the bubb le
tensiometer at 25 °C.
Table 6. Hydroxycarbonyla tion of 1 -dodecene: Io nic liquids as phase transfer ag ents. a
Entry

Surfactant

CMC b
[mM]
Yield (Acid) c
[%]
5 x CMC
TOF d [h -1 ]
5 x CMC
Yield (Acid) c
[%]
c = 0 .5 M
TOF d [h -1 ]
c = 0 .5 M
31 OM IM 135 .3 51.4 10.5 4 3.8 13.1
32 DecMM 3 1.3 45.7 9.2 57 .4 17.8
33 DodecMIM

10.0 1 6.7 3 .1 60.5 29.9
a Experimental conditio ns: Pd(OAc) 2 (0.05 mmol), Pd:SX:TS A (1:4:4 0), m water = 1 2 g,
nonpolar phase (m 1-dod ecene = 3 g, m octane = 9 g), p(CO) = 30 bar, T = 8 5 °C, t = 20 h,
n =12 00 rpm.
b Determined by bubble pre ssure tensiomete r at 25 °C.
c Determined by G C.
d Determined by gas co nsumption at a c onversion o f 20%.

As expected, th e CMC decreases with incr easing carbon chain length from
135.3 mM f or OMIM to 10.0 mM for DodecMIM. Moreover, a signi ficant d ro p
of the yield and the TOF can be found using th e fiv efo ld CMC of each ionic

Results and Discussion
49

liquid in the h ydroxyc arbonyl a tion reaction. The TOF d ecreases f rom 10.5 h -1
with OMIM to 3.1 h -1 with DodecMIM as the phase transfer agent. Since th e
fourfold CMC of eac h ionic liquid is res ponsible for the formation of t he
interfacial area, the oil-water in terface decreases f rom OMIM to DodecMIM,
leading to smaller TOF. In contrast, th e yi e ld and TOF in crease signi ficantly
from OMIM to Dodec MIM u si ng a constant concentration of the ionic liqui d of
0.5 M. Since the CMC is the lowest for DodecMIM, we assu me th at the
interface is larger compared to th e other ionic liquids, res ulting in a high er
TOF. Besides the impac t of the homolog series of the ionic li quid, th e effect o f
concentration has b een stud ied. For this purpose , the OM IM concentrati o n has
been vari ed between 0.1 M and 1.0 M (see Table 7). No reaction takes place
using 0.1 M OMIM in th e water phase because th e CMC was not reached
(Table 7, entry 34). Increasing the OMIM concentration to 0.2 M, the
conversion, yield, and TOF can be significantly enh ance d which is similar to t he
results with non ionic surfactants as th e ph ase tran sfer agent ( PAPER 11 ). In
general, the h igher the OMIM concentration , the hi g her is the in terfacial area
between water and oil, resultin g in an enhancement of conversion, yield, and
TOF. The l:b selectivi ty remains constant at 88:12 and 89:11, respectively.
Interestingly, the isomerization of 1-d odecene accelerates with in creasing OM IM
concentration, leading to the high conversions at high OMIM concentrations.
Table 7. Hydroxycarbonyla tion of 1 -dodecene: Variatio n of OMIM concen tration. a
Entry

Surfactant Surfactant
concentration
[M]
Conversion b
[%] Yield
(Acid) b [%] TOF c
[h -1 ] l:b b Phase
separa-
tion
34 OMIM 0 .1 tr aces traces - - Yes
35 OMIM 0 .2 28.3 22.1 3.6 88:1 2 Yes
36 OMIM 0 .3 37.2 27.8 6.0 89:1 1 Yes
37 OMIM 0 .5 51.1 34.8 7.0 89:1 1 Yes
38 OMIM 0 .7 76.9 52.6 10.4 89:1 1 Yes
39 OMIM 1 .0 84.3 54.9 10.7 88:1 2 Yes
a Experimental conditio ns: Pd(OAc) 2 (0.05 mmol), Pd:SX:TS A (1:4:4 0), m water = 1 2 g,
nonpolar phase (m 1-dod ecene = 3 g, m octane = 9 g), p(CO) = 30 bar, T = 8 0 °C, t = 20 h,
n =12 00 rpm, phase sepa ration at room tempe rature.
b Determined by GC.
c Determined by g as co nsumption at a c onversion of 20%.

In all cases , th e ph ase separation was p ossible at room temperature after th e
reaction, resultin g in quantitative separation into a p ro duct phase (<90% of th e
produ ct) and catalyst containing water ph ase (Pd leachin g <0.5 ppm).
Furthermore, recycling runs indicate th e feasibilit y of th ese systems for th e
hydroxycarbonylation of 1-dod ecene , in cludi ng a sub sequent catalyst recycling

Results and Discussion
50

and p roduct separation. Four runs could be performed without any loss in
catalytic activity a nd low leaching of palladium and phosphorous.
4.5 Alkaline Hydrolysis of long chain ester s
As shown in the p revious sections, the methoxycarbonylation and
hydroxycarbonylation d emand different multiphase systems to facilitate th e
reaction step and the subsequent catalyst recycling step. On the on e h and, a
simple bip hasic system is suff icient for the methoxy carbonylation reaction,
which enab les an excellent reaction performance and qu antitative catalyst
recycling. The proof of concept was al so shown in a continuou s ly operated
miniplant, confirming long-term catalyst stability. On the othe r hand, the
hydroxycarbonylation reaction has to be carried out in microemulsion systems,
since the reaction is hampered in aqueous organic systems b ecause of the low
solubility of the substrates in water. If the carboxy lic acid is th e d esired final
produ ct, two reac tion sequences are supposable (see Figure 18).

Figure 18 . Reaction seq uence for the synthesis of carbo xylic acids from olefins.
First, the described one-pot synt hesis in microemulsion syste ms. Second, a two-
step sequence is possi ble in whi ch th e methoxycarbonylation is performed in
biphasic catalysis, f or ming the corresponding ester, foll owed by an alk aline
hydrolysis to produce the desired carboxyli c acid. Hence, th e alk al ine h ydrolysis
of methyl decanoate has b een investigated as a model reaction, which is
described in detail in PAPER 9 .
4.5.1 Alkaline Hydrolysis in Water
Initially, the alkaline hydrolysis of methyl decanoate has been invest igated in an
aqueous sodium hydroxide solution with n o further additives, vary ing the
temperature between 40 an d 80 °C (see Fi gure 19). For 40 an d 60 °C th e
conversion after 20 h r eaction time is 3 % and 5%, respectively . As exp ected, th e
low solub ility of methyl decanoate in water causes the low r eaction rates,
resulting in low conversions. Su rprisingly, the conversion obtained af ter 20 h
reaction time at a reaction temperature of 80 °C is 82%, although n o further

Results and Discussion
51

additives were u sed. Furth erm ore, the slope of the conversion plot f or the
reaction temperature of 80° C in creases as the reaction proceeds, whi ch is an
atypical trend for a second-order reaction. Obvi o usly, the conversion of methyl
decanoate to sodiu m decanoate accelerates t he reaction. It was found that the
CMC of sodi um decanoate at room temperature is 0.1 mol/L, which is equal to
50% conversion of methyl decanoate. Hence, the f ormation of micelles, init iate d
by the formation of sodiu m decanoate d uring t he reaction, increases the
solubility of methyl decanoate, resultin g in an enh a ncement of th e reaction rate
with proceeding reaction time.

Figure 19 . Effect of the temperat ure o n the co nversion plot of the alka line hydrolys is of methyl
decanoa te in water. Experimen tal conditions: V=2 0 mL, c methyl decanoate =0.2 mol/L,
c NaOH =0.2 mol/L (take n from PAPER 9 ).
Obvi o usly, th e slope of the conversion plot is sligh tly increasing at a conversion
of 40% (see Figu re 19), which confirms this assumpti on, since the CMC of
sodium d ecanoate is reached. We have to keep in mind that the CM C of sodiu m
decanoate is slightly temperature-depend ent, which coul d lead to a small
mismatch.
4.5.2 Alkaline Hydrol ysis in Surf actant-Base d Systems
To enh ance the reac tion performance compared to the unmodified system,
surfactant-based systems has been studied. It was found that both, ionic and
nonionic surfactants, incre ase signi ficantly the in itial reaction rate (see Tabl e 8).
However, the appli cati on of cationic surfactants outp erforms clearly the results

Results and Discussion
52

with the n onionic b enchmark TX100. Since th e head groups of the applied alkyl
trimethylammonium bromides carry a p ositive charge, an electrostatic
attraction of the hydroxide ions is obtained, increasing the local concentration
of hydroxide ion s at the water-oil interface, whi ch enh a nces the init ia l rate of
hydrolysis.
Table 8. CMC va lues and initial reaction rates for the alka line hydrolysis in surfactant-bas ed
systems (take n and modifie d from PAPER 9 ). a
Entry

Surfactant

CMC b
[mM]
Initial rate r 0 c
[mmol/(L·h)]
10 x CMC
Normalized
rate [%]
Initial rate r 0 c
[mmol/(L·h)]
c-CMC = 10 mM

Normalized
rate [%]
40 DeTAB 61.1 383 9 11.9 10 23 3 .5
41 DTAB 1 4.4 2813 8.7 63 2 2.2
42 TTAB 5.8 703 2.2 4 61 1.6
43 CTAB 1.4 322 1 291 1
44 TX100 0.4 81.3 0.25 2 / /
45 / / 5 0 .015 / /
a Experimental conditions: V = 20 mL, c methyl decanoate = 0.2 mol/ L, c NaOH = 0.2 mol/L.
b Determined by bubble press ure tensiometer at 25 °C.
c Determined from the conversio n plot at X = 10%.

Additionally, th e eff ect of th e CMC towards th e reaction performan ce h as b een
investigated for the cationic surfactants. Therefore, th e amoun t of surf actant
was varied in two series of experiments, in which f irstly the tenfo ld CMC a nd
secondly a constant c-CMC val ue o f 10 mM was used. The results are giv en in
Table 8 expressed as t he in itial rates an d normalized rates b ased o n CTAB as
the benchmark . Moreover, the CMC values were d etermined by b ubble pressure
tensiometer. As expected, with in cre asing chain length of th e alkyl chain from
10 to 16, the CMC decreases signif icantly from 61.1 mm ol/L to 1.4 mmol/L,
indicating a higher hydroph o bicity of the cationic surfactant. Using the tenfold
CMC, th e initial rate of hydrolysis decreases from 3839 mm ol/(L ·h) with
DeTAB to 322 mmol/(L·h) with CTAB as th e surfactant. Since the CMC
increases from CTAB to DeTAB, the amoun t of surfactant in the reaction
mixture increases d rastically using the tenfold CMC, res ulting in higher
solubilization of methyl decanoate and thus, in a much higher in itial reaction
rate. Hence, experiments were carried out using th e same concent ration of the
surfactant bu t corrected with the determined CMC (c-CMC = 10 mM). As a
result, the molar concentrati on f or micellization is constant which all ows for a
fairer comparison of the used cation ic surfactants. Interestingly, the same trend
can be observed wher eby the in itial rate decre ases from 1023 mmol/(L·h) f or
DeTAB to 291 mm ol/( L·h) for CTAB. From th e normalized reaction rates, it is
obvious that for the same micellar concentr ation, the rates are closer togeth er,

Results and Discussion
53

showing that the CMC cannot be n eglected in the scree ning of ionic surf actants.
After correction of the surf actant concentrati on by its CMC, the more
hydrophilic cationic surfactant still shows a h igher reaction rate. Two more
effects have to b e cons idered f or the discussion of th e observed reactions rates:
(a) th e solub ilization of methyl decanoate an d (b) the local concentrati on of
hydroxide ions at the water-oil in terface. Considering the aggregation nu mber
for the investigated surfactants, which decreas es from CTAB to DeTAB by a
factor of ab o ut two, the nu mber of micelles for DeTAB as the phase transfer
agent is higher. Hence, th e concentration o f methyl decanoate is higher in the
water phase which explains the higher initial reaction rate. As a result, to
und ers tand the role of th e surfactant in detail, investigation s of the aggregation
behavior, solubilization capacity and p hase behavior is essential.

Conclusion
54

5. Conclusion
Sustainability, recycling and Green Chemistry are n ot only words circlin g in
people´s min ds, th ese words are an inh ere nt part of our life, anchored in all
areas of our society. Particularly in chemical research, much eff o rt is done to
meet the requirements of sustain ability, which has opened the door s to a lot of
new field s in res earch, fulfilling t he d em ands of the society. This th es is is p art of
these efforts, showin g th e ap plicability of alternati ve reaction systems for
chemical synthesis, which makes th e p ro duction of chemicals more sustain able,
more ecological and even more economica l. In general, th e feasibil ity of
multiphase syste ms for the pa lladium-catalyzed met hoxy- a nd
hydroxycarbonylation of different sub strates is shown in this thesis, f acil itating
an easy recycling of the expensive homogeneous catalyst system i n its active
form and the separation of the product via phase separation.
The f irst research focus aimed th e design of a multiphase sys tem for the
palladiu m- catalyzed methoxy carbonylation of 1-dodecene and it s
implementation in a continuously operate d mini plant. For this purpose, an
ordinary liquid/liquid b iphasic system consistin g of methanol as polar catalyst
containing phase and 1-dodecene/oc tane as nonp olar p hase fulfils the
requirements of a good reaction performance and phase separation. It was
shown that the modification of the polar phase with small amounts of water
improves drastically the qu ality of catalyst recycling. Parameter studies in dicate
that the methoxycarbonylation of 1-dodecene in the liquid/liquid biphasic
system is kinetically control led. Moreover, the transfer of the lab scale results to
a continuou sly operated min i plant was successfully p res ented (reaction volu me
scale u p factor: 19), operating continuously over 100 h with stable phase
separation (Pd leaching < 25 ppb) and under steady state cond itions. A
substrate scope was don e to identify th e limitations of the applied b iphasic
system, showin g a stro ng imp act of the hydrophobicity of th e substrate an d the
catalyst concentrati on on the quality of p roduct separation an d catalyst
recycling.
The second research f ocus was set on th e hydroxycarbonylation of 1 -dodecene in
multiphase systems. Alth ough j ust water is used in stead of methanol, compared
to th e methoxycarbonylation, the design of th e multiphase system b ecome s
much more complicated. The solubility of 1-dodecene in the catalyst containing
water ph ase is too low, sup pressing the hyd roxycarbonylation in ordinary
liquid/liquid bip hasic systems. This part focused on th e addition of surfactants
as phase transfer agen ts, acceler ating th e reaction rate an d facilitating the
temperature-induced phase separation for catalyst recycling and p ro duct
separation. While anionic surf acta nts like SDS hamper th e

Conclusion
55

hydroxycarbonylation du e to repulsive interac tion of the a pplied catalyst
complex and the surfactant, cationic and n o nionic surfactants showed p romising
results in terms of reaction performance an d p hase separati on. With th e ionic
liquid OMIM as p hase tran sfer agent, the hyd roxycarbonylation could b e
successfully performed in four consecutive run s without loss in activity and
stable phase se paration . Moreover, th e complex role of non ionic surfactants in
the palladium-catalyzed hyd roxycarbonylation of 1-dodecene was i nvestigated.
Due to th e s urface active properties of the applied catalytic system consistin g of
palladiu m and SulfoXantPhos, it was concluded that the reaction takes place at
the in terface between the oil and water. Hence, not the ph ase b e havior of the
microemulsion system b ut the size and properties of the oil-water interface
determine the reaction performance, whi ch is mainly influenced by the ki nd and
amount of surfactant. In addition, the alkaline hydrolysis of methyl decanoate in
surfactant-based systems was investigated, whi ch can be used to form the
corres pond ing carbo xylic acid as a consecutive step after the
methoxycarbonylation reac tion. The reaction rate can be significantly
acceler at ed by th e ad dition of n onionic and cation ic surfactants, whereby the
electrostatic interaction between th e cationic surfactants an d hydroxide ion s
lead to a stronger improvement of the reaction performance.
All th ings summarized, multiph ase syste ms are a promising tool f or the
recycling of homogeneously d issolved catalyst complexes. How ever, th e selection
of a suitable reaction system is a challenging task, since a lot of aspec ts li ke th e
catalytic syste m, reaction itself, applied substrates, d istribution coefficients and
possible side reactions h ave to b e considered to achieve good reaction
performance an d complete phase separation for catalyst recycling. With that in
mind, multiphase systems can be an i mportant contribution to Green
Chemistry, helping to change the world.

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Monflier, E. Catalysis in Cyclodextrin-Based Unconventional Reaction
Media: Recent Developments and Future Opp ort unities.
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Chem. Eng.
2017 ,
5
(5), 3598.
(69) Hap iot, F.; Bricout, H.; Menuel, S.; Tilloy, S.; Monflier, E. Recent
Breakthroughs in Aqueous Cyclod extrin-Ass isted Su pramolec ular
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of Higher Olefins.
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(8), 1347.
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Cyclodextrins in Biph a sic Cataly sis: A Fruitful Contr ibution of the Host-
Guest Chemistry to th e Transition -Metal Catalyzed Reaction s.
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Hydroesterification of Methyl 10-Undec enoate in Thermomorphic
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of Sustainable Polymer Prec ursors.
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(75) Jessop, P. G. Homogeneous Catalysis Using Supercritical Fluids: Recent
Trends and Systems Studied.
J. Supercrit. Fluids
2006 ,
38
(2), 211.
(76) Bh anage, B. M.; Shirai, M.; Arai, M. ; Ikushima, Y. Mu ltiphase Catalysis
Using Water-Solubl e Metal Complexes in Supercritical Carbon D ioxid e.
Chem. Commun.
1999 , No. 14, 1277.
(77) Koch, D.; Leitner, W. Rh odium-Catalyze d Hyd ro formylation in
Sup erc ritical Carbon Dioxide.
J. Am. Chem. Soc.
1998 ,
120
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(78) Estorach, C. T.; Masdeu-Bult ó, A. M. Hydroesterification of 1 -Alke nes in
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Acknowledgement
63

Acknowled gement
Diese Arbeit hat viel Zeit und Nerven gekostet, aber auch extrem viel Spaß und Freude
bereitet. Zweit eres liegt an der tollen Unterstütz ung von Prof. Schomäck er, der nicht
nur wissens chaftliche Fre iräume zugelassen hat, sondern auch durch viele Diskuss ionen
zum Gelingen dies er Arb eit beige tragen hat.
Ich möchte mich auch bei Prof. Vogt bedanke n, der nicht nur das Zweitgutachte n
übernommen hat, sondern auch durch hervorragenden fachlichen Input bei
verschiedenen Seminaren einen großen Beitrag gelei stet hat.
Für die Übernahm e des Vorsi tzes des Promotions ausschusses möchte ich mich bei Prof.
Friedrich bedank en.
Unzählige Stunden wur den im Labor verbra cht, was jedoch durch meine beiden
blonden Engel Ariane und Caro erheblich vereinfacht wurd e, da eigentlich Sie ja die
ganze Arbeit gemacht haben und mich mit Da ten zugeschüt tet haben. Dank e dafür ! ;)
Auch wenn sie mich manchmal an den Rand eines Nervenzusammenbru chs gebracht
haben, weil Sie per Geisterhand meine Compute rmaus steuer ten oder gefühlte 15 000
Kopien einer Masterarbe it auf me inen Desktop verteil t haben, vermisse ich schon jetzt
die Büroreg eln, Fluchkasse, komi sche Sch reigeräusche und all e ander en B ürospäße. Ih r
seid die Bes ten!
Besonders möchte ich mich auch bei Tobi bedanken, der nicht dur ch fachliche
Disk ussionen extrem geholfen hat, sond ern auch in allen anderen Lebenssituationen da
war.
Ich möchte mich auch bei allen Kollegen de s Sonderforschungsb erei ches TRR 63
bedanken, besond ers aber bei Markus für die hervorragende Zusa mmenar beit während
des letzten Jahre .
Auch bei meinen Studenten Frank, André, Svenja, Johannes und Philipp möchte ich
mich bedanken, die me ine Ideen in Form von Abschlussarbeiten umgeset zt haben un d
somit auch einen g roßen Beitrag di eser Arbeit geleis tet haben.
Ein Dank gehört auch allen Kollegen des AK Schomäcker – Gabi, die immer zur Stelle
war, wenn die GC nicht so wollte wie ich – Fra u Löh r, di e die unl iebsame Bürokra tie
der Uni für mich übernommen ha t – Micha, der immer für neue Ideen zu begeistern ist
– Samira, dass sie auch mal einen Burani geholt hat – M ax und L ukas für die
verrückten Disk ussionen – Natasa und Martin, dass sie oft Zuflucht auf unserer Couch
gesucht haben, u m eine Kaf feepause zu mach en und Juli an, den ich seit de m ersten Tag
des Studiums ken ne und nun auch wi eder bei mir im Büro ist. :)
Zu guter Letzt möchte ich mich bei meinen Eltern bedanken, da sie immer für mich da
sind und bei meiner Michi, dass sie zum Einen schon seit 3 Jahren wöchentlich fragt,
wann ich denn endlich mit der Promotion fertig sei ;) und zum Anderen, dass Sie mich
immer unterstützt hat, die Doktorarbeit versu cht hat zu vers tehen ;) und einfach
immer für mich da ist. I ch hab dich l ieb! ;)

Appendix
64

Appendix
Table A1 . Applied catalyst components, s upplier and purity .
Catalyst pre cursors and l igands Supplier Purity [%]
2,7-Bis(SO 3 Na) -4,5-Bis(d iphenyl phosphino)-
9,9-dimethylx anthene (S ulfoXant Phos) Molisa GmbH -
3,3',3''-Phosphane triyltri s(benzenesul fonic
acid) trisodi um salt (T PPTS) ABCR 95
4,5-Bis(diphenyl phosphi no)-9,9-
dimethylxanthen e (Xan tPhos) Sigma-Aldrich 97
Dicarbonyl (acetylaceton ato)rhodi um(I) Umicore
Dichloro-(1,5- cyclooctadi ene)-palladiu m(II) Sigma-Aldrich 99
Methane sulfonic a cid Sigma-Aldrich 99.5
Palladium a cetate Sigma-Aldrich 99.9
Allyl palladium(II) chlori de dimer Sigma-Aldrich 98
p
-Toluene sulfonic acid Sigma-Aldrich 98
Triphenylp hosphine (TP P) Sigma-Aldrich 99

Table A2 . Applied substrate s, supplier and p urity.
Substrates Supplier Purity [%]
1-Dodecene Merck 94
1-Octene Sigma-Aldrich 98
10-Undecenoic acid meth ylester Sigma-Aldrich 96
Cyclohex ene Sigma-Aldrich 99
Methyl decanoat e Sigma-Aldrich 99
Styrene Sigma-Aldrich 99

Appendix
65

Table A3 . Applied solve nts, supplier and pu rity.
Solvents Supplier Purity [%]
1-octanol Roth 99
n-octane ABCR 98
n-decane Merck 94
n-dodecane Fluka 98
n-tetradecane Sigma-Aldrich 92
n-hexadecane Merck 99
methanol VWR HPLC grade
water VWR HPLC grade

Table A4 . Applied surfacta nts, supplie r and purity.
Surfactants Supplier Purity [%]
Marlipal 24/20-9 0 Sasol technical grade

Marlipal 24/20-9 0
Sodium dodecyl sulfate ( SDS)
Sasol
Sigma-Aldrich
technical grade
99
Tetradecyl trimethylamm onium bromide (TTAB ) Sigma-Aldrich 99
Triton X-100 Sigma-Aldrich tec hnical grade

Triton X-114 Sigma-Aldrich tec hnical grade

Decyltrime thylammoni um bromide (DeT AB) ABC R 99
1-Methyl -3-decylimi dazolium bromide (DecMIM ) Iol itec 99
1-Methyl -3-dodecylimidazol ium bromide (DodecM IM) Iol itec 99
1-Methyl -3-octylimidazoli um bromide (OMIM) ABCR 99
Dodecyltrime thylammoni um bromide (DTAB ) Sigma-Aldrich 98
Hexadecyltrim ethylamm onium bromide (CTAB ) Roth 99

PAPER 1
Superior cataly st recyclin g in surf actant based mul tiphase
systems - Qu o vadis catalyst c omplex?
Tobias Pogrzeba, David Müller, Markus Illner, Marcel Schmidt, Yasemin
Kasaka, Ariane Weber, Günter Wozny, Reinhard Schomäcker, Michael
Schwarze
Chemical Engineering and Proc essing: Process Intensification, 2016, 99, 155-166

Online Article:
http s://www .sciencedirect.com/science/article/pii/S0255270115300957

Reprinted w ith permission from “Superior catalyst recycling in surfac tant base d
multiphase systems – Quo vadis catalyst compl ex?; Tobias Pogrzeba, David
Müll er, Markus Illner, Marcel Schmid t, Yasemin Kasaka, Arian e Weber, Günter
Wozny, Reinhard Schomäc ker, an d Michael Schwarze. Chemical En gineering
and Processing, 2016, 99, 155-166.” Copyright (2015) Elsevier B.V.

Superior

cataly st

recy cling

in

surfactant

based

multiphase

syst ems

–
Quo

v adis

cataly st

comple x?
T.

Pogrzeba
a ,
* ,

D.

Müller
b
,

M.

Illner
b
,

M.

Schmidt
a
,

Y.

Kasaka
a
,

A.

W eber
a
,

G.

W ozn y
b
,
R.

Schomäcker
a
,

M.

Schw arze
c
a
T echnische

Universität

Berlin,

Department

of

Chemistry ,

TC-8,

Str .

des

17 .

Juni

124 ,

1 0623

Berlin,

Germany
b
T echnische

Universität

Berlin,

Chair

of

Process

Dynamics

and

Operation,

KWT

9,

Str.

des

17 .

Juni

1 35,

1 0623

Berlin,

Germany
c
T echnische

Universität

Berlin,

Chair

of

Plant

and

Processs

Safety ,

TK -0 1 ,

Str a ß e

des

17 .

Juni

1 35,

1 0623,

Berlin,

Germany
A

R

T

I

C

L

E

I

N

F

O
Article

history :
Receiv ed

9

March

20 1 5
Receiv ed

in

revised

form

7

July

20 1 5
Accepted

3

September

20 1 5
A v ailable

online

9

September

20 1 5
K eywords:
Microemulsion

systems
Surfactants
Catalyst

R ecycling
Process

Design
Separation
A

B

S

T

R

A

C

T
Microemulsion

systems

are

smart

solvent

systems

which

can

be

applied

in

homogeneous

catalysis.

We
investigate

these

multiphase

systems

to

e xploit

their

charact eristics

for

catalytic

gas/liq uid

reactions

and
processes

in

aqueous

media.

One

critical

aspect

from

an

economic

perspective

is

the

q uantitative
recy cling

of

the

catalyst

complex

dissolved

in

the

multiphase

system.

Therefore,

it

is

important

to

know
the

distribution

of

the

catalyst

complex

in

each

of

the

single

phases.

In

this

contribution

we

analyse

the
different

parameters/fact ors

that

may

have

an

in fl uence

on

the

distribution

of

catalyst

complex es

in
microemulsion

systems,

e.g.

temper ature,

type

of

ligand,

structure

of

surfactant,

and

chain

length

of
surfactant.

Afterwar ds,

the

derived

information

is

used

for

the

design

of

a

real,

industry-oriented
application:

h ydroform ylation

of

long

chained

alkenes.

Hereby ,

special

attention

is

giv en

to

the
separation

step

of

a

process,

which

is

performed

after

a

homogeneously

catalyzed

reaction

step

in

a
microemulsion

system.

Process

and

economic

constraints

are

brie fl y

outlined

and

compared

with
operation

data,

aiming

for

the

reuse

of

the

catalyst

in

the

reaction

step

and

reduced

leaching

into

product
streams,

even

in

the

case

of

operational

disturbances

and

shifts

in

the

catalyst

distribution.
ã

20 1 5

Elsevier

B.V.

All

rights

reserved.
1.

Introduction
Expen siv e

nobl e

metal

cat al ysts

ar e

oft en

appl ie d

in

homog e-
neous

cat al ysi s.

The

aims

here b y

ar e

high

acti vity

and

selec ti vi ty

at
moder ate

reac tion

condi tio ns .

Ho wev er ,

to

esta bl ish

a

lar ge-s cal e
pr oce ss,

the

q uan tit ativ e

reco very

of

thes e

cata ly sts

is

cruc ial

and
shoul d be pos si ble withou t lo ss in act iv it y/sel ect i vity . Hence , reac tion
media

that

combi ne

the

adv antag es

of

homog enous

catal ysi s

(high
turno ver

fr eq uencies

and

high

sele cti vity)

and

tw o-p hase-c atal ysi s
(easy

sepa r ation

of

cat al yst

and

pr oduct )

ar e

of

gr eat

int er es t.

Besi de
the

cla ssi cal

aq ueo us-or ganic

tw o-pha se

sy st ems,

i.e .

for

the
h ydrofo rm yla tio n

of

1-pr op ene

to

n-b utanal

in

the

Ruh r che mie/
Rhône -Po ule nc

Pr ocess

[1] ,

man y

ne w

sy st ems

ha v e

been

dev el oped
durin g

the

last

decade s.

We l l

kno wn

e xa mples

ar e

ion ic

liq uids

[2,3] ,
supe rc ri tical

media

based

on

CO
2
[4,5] ,

therm omo rp hic

sol v ent
mixtu r es

[6] ,

supp ort ed

ion ic

liq uid-ph ase

(SI LP)

[7] ,

or

sol-g el
immob ili zed

catal yst

sy st ems

[8] .

An

alt er nati v e

appr oach

is

the
appl ica tion

of

micr oemulsi on

sy st ems

as

tune abl e

sol v ents

for

the
recy cli ng

of

w at er -solubl e

cat al yst s.

Micr oem uls io n

sy st ems

ar e
ter nar y

mixtu r es

cons is ting

of

a

non-p olar

compo un d

(oil) ,

a

pola r
com pound

(w ater) ,

and

a

surf act ant

(oft en

non-i onic

surf act an ts

ar e
chos en

in

this

cont e xt ).

The y

pr ovi de

a

high

int erf ac ial

ar ea

betw een
the

polar

and

non-p olar

dom ain s

durin g

the

reac tion.

Addi ti on all y ,
thei r

phase

sepa r ati on

beha viou r

can

be

manip ula t ed

thro ugh
tem pe ra tur e ch ang es . Ho wev er , for th e ap plica tion of mic r oem uls ion
sy st ems

their

phase

beh a viour ,

which

no t

onl y

depen ds

on
tem pe ra tur e

but

also

on

their

com posit ion

and

the

int er ac tio n
betw een

the

surf act ant

and

the

cata ly st/re act ant s,

has

to

be

studi ed
in

det ail

[9] .

Among

the

a v ai lable

gr een

solv ents,

micr oem uls io n
sy st ems, easily tuneab le b y the selecti on of an appr opriat e surfact an t,
show

supe rio r

char acter is tics

for

catal ytic

reac tions

and

pr oce sses

in
aq ueo us

media .

Furt hermor e,

the y

ful fi l

all

req uir eme nts

neede d

for
succ essf ul

and

ef fi cie nt

catal yst

recy cli ng.

Exa mples

for

the

appli ca-
tion

of

micr oem uls ion s

as

reac tion

sy st em

ar e

the

h ydrog en ati on

of
dimet hy l

itaco na te

with

Rh/ TPPT S

[1 0] ,

the

Suz uki

coupl ing

of

2-
br omob enz onit ril e

and

4-met hy lb enzen eb or oni c

acid

with

Pd/
TPPT S

[1 1]

and

the

h ydrofo rm yla ti on

of

1-dod ecene

with

Rh/SX
[1 2] .

For

furth er

e xam ples

see

also

[9] .
In

this

contribution

we

will

ev aluate

and

discuss

the

distribu-
tion

of

homogeneous

cataly st

complex es

in

microemulsion
*

Corresponding

author .
E-mail

address:

[email protected]

(T .

Pogrzeba).
http://dx.doi.org/1 0. 1 01 6/j.cep.20 1 5.09.0 03
0255-270 1/ ã

20 1 5

Elsevier

B.V.

All

rights

reserved.
Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6
Contents

lists

available

at

ScienceDirect
Chemical

Engineering

and

Pr ocessing:
Pr ocess

Intensi fi cation
journa l

homepa

ge:

www.elsev

ier.com/locate/cep

syst ems

by

the

v ariation

of

different

parameters,

e.g.

temper ature,
ligand,

structure

of

surfactant,

and

chain

length

of

surfactant.

We
will

also

discuss

sever al

aspects

which

are

important

for

the
application

of

microemulsion

syst ems

for

a

closed

recy cle

catalytic
process

with

respect

to

the

choice

of

the

surfactant.

In

addition,

we
will

present

a

case

study

to

design

a

process

for

homogeneous
catalysis

in

a

microemulsion

syst em

with

ef fi cient

catalyst
recy cling

based

on

the

results

of

the

fi rst

part

of

this

contribution.
2.

Aqueous

surfactant

media
Wa t e r

can

act

as

a

solv ent

for

w ater -soluble

catalysts

and
enables

the

biphasic

extraction

of

non-polar

products

as

well

as

the
recy cling

of

catalysts.

How ever ,

in

case

of

h ydrophobic

reactants

it
has

the

disadvantage

of

poor

reactant

solubility .

The

addition

of

a
surfactant

increases

the

solubility

of

non-polar

reactants

in

the
aqueous

phase.

Generally ,

there

are

two

different

approaches

to
create

aq ueous

surfactant

media

for

homogeneousl y

catalysed
reactions.
The

fi rst

approach

is

to

creat e

an

aq ueous – micellar

solution

by
the

addition

of

a

surfactant

to

wate r ,

which

ex ceeds

the

critical
micelle

concentration

(cmc).

Micelles

are

nano-scale

aggregates

of
surfactant

monomers,

which

are

able

to

solubilize

organic
components

in

their

cores.

Since

the

size

of

micelles

is

usually
very

small,

the

concentration

of

substrate

in

an

aq ueous – micellar
solution

is

often

low er

than

in

conventional

organic

solv ents.

The
cmc

and

the

size

of

micelles

depend

on

the

type

of

surfactant.

In
general,

non-ionic

surfactants

form

larger

micelles

and

ha ve

a

low
cmc

in

comparison

to

ionic

surfactants.
The

second

approach

is

the

use

of

microemulsion

syst ems,
which

are

formed

at

surfactant

concentrations

much

higher

than
the

cmc.

By

the

addition

of

a

non-ionic

surfactant

of

the

type

C
i
E
j
to
a

biphasic

mixture

of

w ater

and

oil,

usually

four

different

states

can
be

observed

that

wer e

classi fi ed

by

Winsor

(Winsor

systems

I – IV).
In

C
i
E
j
, i

is

the

number

of

h ydr ocarbon

groups

of

the

surfactant ’ s
h ydrophobic

part,

and

j

is

the

number

of

ethoxylat e

groups

of

its
h ydrophilic

part.

Important

parameters

to

characterize

the
mixture

are

the

weight

fractions

a

and

g .

In

Eq.

(1)

m
oil
is

the
mass

of

oil,

m
water
is

the

mass

of

water

and

m
surf
is

the

mass

of

non-
ionic

surfactant.
a

¼ m
oil
m
oil
þ

m
water
g

¼ m
surf
m
oil
þ

m
water
þ

m
surf
ð 1 Þ
In

Fig. 1

the

phase

beha viour

of

a

tern ary

mixtu r e

of

oil,

wa ter

and
non -ioni c

surfa cta nt

is

sche mat ica ll y

show n

for a

const an t

va lu e

of a .
At

low

temper atures

the

surfactant

is

mainly

solubilized

in

w ater ,
whereas

its

solubility

in

oil

increases

at

higher

temper atures.

Thus,
the

illustrat ed

seq uence

of

phases

as

a

function

of

temperatur e

is

the
result

of

the

gradual

change

in

the

surfactant's

solubility

from
h ydrophilic

to

h ydrophobic.

The

phase

sequence

generally

starts

at
low

temper atures

with

an

oil-in-water

(o/w)

microemulsion

( 2 ,
Winsor

I).

This

microemulsion

consists

of

oil-bearing

micelles

in

a
continuous

wate r

phase

which

is

in

equilibrium

with

an

organic
ex cess

phase.

At

intermediate

temper atures

a

three-phase

region
(3,

Winsor

III)

exists,

where

the

surfactant

is

almost

equall y

soluble
in

both

liq uids

and

forms

a

surfactant

rich

microemulsion

phase

in
the

middle

of

two

ex cess

phases.

For

even

higher

temperatur es

a
wat er -in-oil

(w/o)

microemulsion

( 2,

Winsor

II)

is

formed.

Here,
wat er -bearing

inverse

micelles

exist

in

a

continuous

oil

phase,
which

is

in

equilibrium

with

a

wate r

ex cess

phase.

If

the
concentration

of

surfactant

in

the

ternary

mixture

is

high

enough
for

the

complete

solubilization

of

oil

and

w ater ,

a

one-phase
microemulsion

(1 ,

Winsor

IV)

of

the

entire

volume

will

be

formed,
which

can

be

an

o/w-,

bicontinuous-

or

w/o-microemulsion
depending

on

the

oil

content

in

the

mixture.
In

general,

each

of

the

four

Winsor

states

can

be

applied

as

a
reaction

medium

for

homogeneous

catalysis.

Since

the

phase
behaviour

of

a

microemulsion

system

can

be

changed

as

a

function
of

temperatur e

and

surfactant

concentration,

it

is

possible

to

adjust
the

reaction

syst em

between

different

process

steps

with

v arying
req uirements

[1 3] .

The

choice

of

the

applied

surfactant

has

to

be
made

carefully

so

that

the

req uirements

for

a

homogenousl y
catalysed

reaction

with

subsequent

product

separation

and
catalyst

recy cling,

can

be

ful fi lled.

Besides

its

in fl uence

on

the
phase

beha viour ,

the

surfactant

will

ha ve

a

strong

impact

on

the
distribution

of

reactants

and

cataly sts

between

the

aq ueous

and
the

organic

phase.

For

the

q uantitative

recy cling

of

a

homo-
geneousl y

dissolved

catalyst

comple x

from

multiphase

syst ems

as
well

as

the

ev aluation

of

the

reaction

kinetics

it

is

important

to
know

the

distribution

of

the

catalyst

comple x

between

the

single
phases.

In

general,

based

on

the

experience

with

conventional
organic-aqueous

two-phase

syst ems,

water -soluble

catalyst

com-
plex es

are

preferentiall y

dissolv ed

in

the

aqueous

phase

(see

e.g.
the

Rh/TPPTS

comple x

in

the

R CH/RP

process)

and

h ydr ophobic
counterparts

are

dissolv ed

in

the

oil

phase.

For

microemulsion
syst ems,

the

interactions

between

the

surfactant

and

the

catalyst
complex

can

in fl uence

the

solubility

of

the

latter

considerably .

In
man y

cases

the

cataly st

follow s

the

surfactant

into

the

corre-
sponding

microemulsion

phase,

which

results

in

different

separa-
tion

tasks

for

the

catalyst

recy cling

during

a

process

step
depending

on

the

phase

behaviour

of

the

microemulsion

syst em.
Therefore,

it

is

necessary

to

indicate

the

parameters

which

are
responsible

for

the

catalyst

distribution

in

such

surfactant

based
multiphase

syst ems

to

select

the

best

surfactant

as

well

as

ideal
operating

conditions

that

result

in

a

q uantitative

catalyst

recy cling
and

an

optimal

separation

process.
3.

Catalyst

distribution

in

multiphase

systems
To

analy se

the

effects

of

the

different

parameters

on

the

catalyst
distribution

multiple

experiments

wer e

carried

out.

The

obtained
information

from

these

experiments

wa s

then

used

for

an

actual
industry-oriented

application.

In

the

following,

details

on

these
experiments

as

well

as

the

results

are

presented.
3. 1 .

Experimental
3. 1 . 1 .

Chemicals
The

solv ents

1-dodecene

(94%),

w ater

(HPLC

grade),

and
tetrah ydrofuran

(THF ,

99.5%)

were

purchased

from

VWR.

The
Fig.

1.

Phase

diagram

(commonly

called

fi sh-diagram)

for

a

ternary

mixture

of

oil,
water ,

and

non-ionic

surfactant

at

a

constant

ratio

of

oil

and

water

with

normal
(bottom)

and

inv erse

(top)

micelles.

The

fi gure

has

been

modi fi ed

from

[1 3] .
15 6

T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

surfactants

Marlipal

24/50,

Marlipal

24/60

and

Marlipal

24/70

were
a

donation

from

Sasol.

The

surfactant

T riton

X- 1 1 4 ,

the

amphi-
philes

C
4
E
1
(99%)

and

C
4
E
2
(99.2%),

the

h ydrophobic

ligands
triphen ylphosphine

(TPP ,

99%)

and

Xantphos

(97%)

and

the
rhodium

standard

solution

(1 01 1

mg/L)

for

ICP-OES

analysis

were
receiv ed

from

Sigma – Aldrich.

The

wat er -soluble

ligands

3,3
0
,3
00
-
phosphanetriyltris(benzenesulfonic

acid)

trisodium

salt

(sodium
triphen ylphosphine

trisulfonate,

TPPTS,

95%)

and

sulfonated

4,5-
bis(diphen ylphosphino)-9,9-dimeth ylxanthene

(SulfoXantphos,
SX)

wer e

purchased

from

ABCR

and

Molisa

GmbH,

respectivel y .
The

rhodium

precursor

Rh(acac)(CO)
2
was

a

donation

from
Umicor e.

To

adjust

the

ionic

strength

we

used

sodium

sulfate
(Na
2
SO
4
,

99%)

purchased

from

Merc k.

All

the

chemicals

wer e

used
without

further

puri fi cation.
3. 1 .2.

Prepar ation

of

the

catalyst

complex
For

the

prepar ation

of

the

catalyst

comple x,

1 2.9

mg
(0.05

mmol,

1

eq.)

Rh(acac)(CO)
2
and

the

investigat ed

ligand
(1 0

eq.

for

the

monodentate

ligands

and

5

eq.

for

the

bidentate
ligands)

were

ev acuated

three

times

in

a

Schlenk

tube

and

fl ushed
with

argon.

The

solv ent

(2

g

degassed

wate r

for

the

h ydrophilic
ligands

and

3

g

THF

for

the

h ydrophobic

ligands)

was

added
through

a

septum.

Then

the

catalyst

solution

wa s

stirred

ov er

night
at

room

temperatur e

to

ensure

the

formation

of

the

catalyst
comple x.
3. 1 .3.

In vestigation

of

the

phase

behaviour
Standard

experiments

were

carried

out

by

using

a

micro-
emulsion

syst em

consisting

of

w ater

as

the

h ydr ophilic

compound,
1-dodecene

as

the

h ydr ophobic

oil

( a

=

50%),

the

investigat ed

non-
ionic

surfactant

( g

=

8%)

and

a

sodium

sulfate

amount

of

1

wt%.

To
ensure

the

three

phase

region

for

the

other

amphiphiles,

C
4
E
1
and
C
4
E
2
,

the

concentration

had

to

be

increased

to

g

=

20%.

The
compounds

were

weighted

into

a

glass

reactor

with

a

heating
jacket.

The

lid

of

the

react or

offers

connections

for

sampling,

for
v acuum

establishment,

and

argon

inertisation.

The

samples

were
ev acuated

and

fl ushed

with

argon

three

times.

Then

the

catalyst
solution

wa s

injected

with

a

syringe.

We

studied

the

phase
behaviour

from

25

C

to

91

C

in

1

C

steps.

For

this

purpose,

we
adjusted

the

temperatur e

with

a

thermostat

while

stirring

the
microemulsion.

After

the

desired

temperatur e

wa s

reached,

the
stirrer

was

stopped

and

the

phase

separation

was

observed.
Samples

of

the

different

phases

wer e

taken

to

determine

the
rhodium

concentration

in

each.
3. 1 .4.

Determination

of

the

rhodium

concentration
The

concentration

of

rhodium

in

the

different

phases

wa s
determined

by

inductively

coupled

plasma

optical

emission
spectrometry

(ICP-OES)

using

a

Varian

ICP-OES

71 5

ES

instrument.
In

each

case,

we

analysed

the

aqueous

phase

and

the

middle

phase
of

the

three

phase

syst em.

Therefore,

2

mL

of

the

wate r

or

1

mL

of
the

middle

phase

wer e

added

to

an

ICP

tube

and

treated

with
freshl y

prepar ed

aqua

regia.

Afterw ards,

the

samples

were

diluted
with

degassed

w ater

and

the

rhodium

concentration

was
measured

at

a

wa velength

of

369

nm.

A

calibration

of

the

setup
wa s

performed

with

rhodium

standard

solutions

ha ving

concen-
trations

of

1,

5

20,

50,

and

15 0

mg/L.
3.2.

Phase

behaviour

of

the

in vestigated

microemulsion

systems
To

ensure

an

ef fi cient

recy cling

of

the

cataly st

comple x

after

the
reaction,

it

is

of

utmost

importance

to

know

the

phase

behaviour

of
the

reaction

mixture.

This

phase

behaviour

strongly

depends

on
the

selected

amphiphile.

Several

publications

generalize

observed
effects

[1 4, 1 5] ,

but

to

date

and

to

the

best

of

our

know ledge

the
in fl uence

of

the

used

catalyst

comple x

has

not

been

studied

in
detail.

Therefore,

we

fi rstly

tested

different

amphiphiles

to

obtain
the

in fl uence

of

the

chain

length,

structure,

and

the

h ydrophobic
character

of

the

amphiphiles

to wards

the

position

of

the

three
phase

region

on

the

temperatur e

scale

(see

Fig.

2 ).

Based

on

this
information,

the

next

step

was

to

investigate

the

in fl uence

of
ligands

and

thus

the

catalyst

complex

in

particular

in

the
subseq uent

sections.

For

the

sake

of

completeness

it

has

to

be
mentioned,

that

some

of

the

applied

chemicals

are

technical

grade
and

may

contain

impurities

which

can

hav e

an

impact

on

the

phase
behaviour

of

the

investigat ed

microemulsion

syst ems

and
therefor e

ha ve

to

be

considered.
3.2. 1 .

Hydrophobicity

in fl uence
It

is

well

known

that

the

three

phase

region

for

short

chained
amphiphiles,

such

as

C
4
E
1
and

C
4
E
2
,

has

a

broad

temper ature

range.
As

expected,

for

the

h ydrophilic

amphiphiles

the

position

of

the
Fig.

2.

Phase

behaviour

for

different

surfactants

(
a

=

50%,

g

=

8%

(
g

=

20%

for

C
4
E
1
and

C
4
E
2
),

1

wt.%

sodium

sulfate,

n
Rh(acac)CO
2
=

0.05

mmol,

n
SX
=

5

eq.).
T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

15 7

three

phase

region

is

shifted

to

higher

temperatur es.

The

same
effect

of

the

three

phase

region

being

shifted

to

higher

temper -
atures

with

increasing

h ydrophobicity

e xists

for

technical

grade
surfactants

of

the

Marlipal

series,

which

are

long

chain

aliphatic
surfactants

(see

Fig.

3 ).

It

is

characteristic

for

these

surfactants

that
they

form

micelles

as

a

microstructure.

By

increasing

the

degree

of
ethoxylation

from

5

in

Marlipal

24/50

to

7

in

Marlipal

24/70

the
h ydrophilic

character

increases

and

the

three

phase

region

is
shifted

to

higher

temper atures.

In

comparison

to

the

short

chained
amphiphiles

the

temper ature

range

of

the

three

phase

region

is
often

limited

to

5 – 10

K.

It

must

be

kept

in

mind

that

short

chained
amphiphiles

only

act

as

solubilisers

and

do

not

form

micellar
structures.
3.2.2.

Chain

length

in fl uence
The

difference

in

the

size

of

the

temper ature

range

of

the

three
phase

region

of

short

compared

to

long

chain

amphiphiles

is

due

to
their

different

solubilisation

properties

in

oil

and

w ater .

Short
chained

amphiphiles,

which

act

as

an

additional

solv ent,

can
dissolve

more

oil

and

w ater

in

their

own

phase

compared

to

the
technical

grade

surfactant

Marlipal.

This

leads

to

a

broad

range

of
the

three

phase

region.
3.2.3.

Surfactant

structure
Of

special

inter est

is

the

in fl uence

of

the

structure

of

the
surfactant

to wards

the

position

of

the

three

phase

region.
Therefore,

we

compared

different

surfactants

with

the

same
degree

of

ethoxylation

which

are

illustrat ed

in

Fig.

3 :

Marlipal

24/
70

with

a

linear

h ydrophobic

carbon

chain,

T riton

X- 1 1 4

holding

a
branched

carbon

chain

with

a

phen y l

unit

as

linker ,

and

NP7 ,

which
also

has

a

phen yl

unit

as

linker ,

but

a

linear

carbon

chain.

Due

to

the
different

properties

of

the

h ydr ophobic

part

of

the

surfactants,

we
obtain

v ariable

positions

of

the

three

phase

region.

T riton

X-
11 4

and

NP7

ha ve

the

same

number

of

carbon

atoms,

but

T riton

X-
11 4

is

branched.

Hence

Trito n

X- 1 1 4

is

more

h ydrophilic

than
NP7

and

so

the

three

phase

region

is

established

at

higher
temperatur es.
3.2.4.

Ligand

in fl uence
Another

important

in fl uence

factor

on

the

position

of

the

three
phase

region

is

the

type

of

applied

ligand.

The

experimental

results
are

shown

in

Fig.

4 .

The

refer ence

is

a

mixture

with

rhodium
precursor

without

an y

ligand.

We

test ed

the

monodentate

ligands
TPP

and

TPPTS

and

the

bidentate

ligands

Xantphos

and

SulfoX -
antphos

(see

Fig.

5 ).

At

fi rst

glance,

the

water -soluble

ligands

TPPTS
and

SulfoXantphos

shift

the

three

phase

region

to

higher
temper atures.

This

is

a

result

of

the

catalyst

prepar ation

though.
The

h ydrophobic

catalyst

complex es

wer e

prepared

using

little
amounts

of

THF ,

which

is

more

h ydrophilic

in

comparison

to

1-
dodecene.

It

is

well

known

that

the

h ydr ophobicity

of

the

oil
in fl uences

the

position

of

the

three

phase

region

[1 5] .

The

less
h ydrophobic

the

oil,

the

low er

the

position

of

the

three

phase
region

is.

The

difference

of

the

position

of

the

three

phase

region
for

TPPTS

and

SulfoXantphos

is

due

to

the

ligand

concentration.

We
used

10

eq.

of

the

monodentate

TPPTS

and

5

eq.

of

the

bidentate
SulfoXantphos.

As

a

result

the

w ater

solubility

of

the

surfactant
decreases

according

to

the

salting

out

phenomenon

of

the

sulfate
anions

[1 6] ,

thus

shifting

the

position

of

the

three

phase

region

to
low er

temper atures

[1 4] .
Based

on

these

results,

we

mov ed

on

to

investigat e

the
parameters

in fl uencing

the

distribution

of

the

whole

catalyst
complex.
3.3.

Distribution

of

the

catalyst

complex
Not

only

is

the

temper ature

range

for

the

different

phases
crucial

for

the

separation

process,

but

also

the

distribution

of

the
catalyst

complex

between

the

different

phases.

For

a

feasible

and
economic

process

it

is

necessary

to

achieve

a

quantitativ e
separation

of

the

expensiv e

catalyst

comple x.

Therefore,

it

is
essential

to

estimate

or

manipulate

the

interactions

between

the
catalyst

complex

and

the

amphiphile.

For

this

reason

we
investigat ed

different

amphiphiles

and

different

ligands,

which
ha ve

an

in fl uence

on

the

distribution

characteristics

of

the

catalyst
complex.

Qualitatively

speaking,

the

distribution

can

be

estimated
visually

by

the

colour

of

the

different

phases

(see

Fig.

6 ),

but

for
quanti fi cation

we

measured

the

amount

of

rhodium

by

ICP-OES.

In
Fig.

7

the

in fl uence

of

different

amphiphiles

on

the

distribution

of
the

water -soluble

Rh/SX

comple x

is

shown.

The

rhodium

content
in

the

oil

phase

is

negligible

because

of

the

w ater -soluble
SulfoXantphos

ligand

as

shown

in

[1 7 , 1 8] .

So

for

the

inv estigation
of

the

catalyst

comple x

distribution

only

the

rhodium

amount

in
the

aq ueous

phase

and

the

middle

phase

wa s

considered.

How ever ,
it

should

be

mentioned

that

minor

rhodium

leeching

into

the

oil
phase

was

found

in

the

order

of

0. 1

ppm

[1 8]

so

that

post-
treatment

of

the

organic

phase

would

be

necessary

for

complete
rhodium

recove ry .
For

the

short

chain

amphiphiles

C
4
E
1
and

C
4
E
2
a

high

amount

of
the

rhodium

complex

is

present

in

the

aqueous

phase.

The
distribution

of

the

rhodium

complex

depends

on

the

partition
coef fi cient

between

the

phases.

For

the

short

chain

amphiphiles,
the

ma jor

reason

for

the

cataly st

distribution

is

the

different
polarity

of

the

phases,

which

increases

from

the

oil

phase

ov er

the
amphiphile

rich

middle

phase

to

the

wate r

phase.

For

the
amphiphile

C
4
E
1
,

the

middle

phase

is

too

non-polar

to

dissolv e
the

catalyst

comple x

to

a

suf fi cient

e xtent

and

only

34%

of

the
rhodium

is

located

in

the

middle

phase.

For

the

amphiphile

C
4
E
2
,
the

middle

phase

is

more

h ydr ophilic

and

allows

for

about

82%

of
the

catalyst

complex

to

be

located

there.

As

a

consequence,

the
amount

of

rhodium

in

the

aq ueous

phase

is

higher

in

the

C
4
E
1
syst em

in

comparison

to

the

C
4
E
2
syst em.

In

contrast,

the

rhodium
amount

in

the

aq ueous

phase

of

the

Marlipal

systems

is

only
between

1 .7%

and

3.7%

of

the

ov erall

amount

of

rhodium

in

the
syst em.

Apparently ,

the

catalyst

comple x

follow s

the

surfactant
Fig.

3.

Structures

of

the

different

investigated

surfactants.
15 8

T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

into

the

surfactant

rich

middle

phase

of

the

microemulsion
syst ems.

We

assume

that

the

water -soluble

catalyst

complex

is
also

surface

active

and

attaches

itself

to

the

oil – wate r

interface

of
the

bicontinuous

phase

of

the

microemulsion

system.
Besides

the

amphiphile

the

kind

of

ligand

has

a

strong

in fl uence
on

the

distribution

of

the

cataly st

comple x.

In

Fig.

8

the
distribution

of

rhodium

in

the

presence

of

different

ligands

is
shown.

It

is

clear

that

the

h ydrophobicity

of

the

ligand

is

crucial

for
the

distribution

of

the

rhodium.

For

the

w ater -soluble

ligands
TPPTS

and

SulfoXantphos

the

rhodium

comple x

is

located

in

the
middle

phase

to

a

larger

extend.

The

high

amount

of

Rh/TPPTS

in
the

aqueous

phase

(40%)

is

due

to

the

high

number

of

sulfonate
groups

per

comple x.

In

comparison

to

the

w ater -insoluble

ligands
TPP

and

Xantphos,

as

well

as

for

the

unmodi fi ed

rhodium
precursor ,

the

rhodium

species

is

mainly

located

in

the

oil

phase.
Here,

only

10 %

of

the

Rh/TPP

complex

and

26%

of

the

Rh/Xantphos
comple x

are

located

in

the

middle

phase.

The

comparison

of

mono-
and

bidentate

ligands

with

respect

to

the

distribution

of

the
rhodium

complex

is

dif fi cult,

because

a

different

number

of
comple x

species

can

be

formed.

The

number

of

coordinat ed

ligands
is

important

for

the

h ydrophilic

or

h ydrophobic

character

of

the
catalyst

comple x.
Furthermore,

we

investigat ed

the

distribution

of

the

Rh/
SulfoXantphos

catalyst

in

a

Winsor

I

and

II

system

with

the
surfactant

Marlipal

24/7 0,

since

this

catalyst

comple x

is

of

high
interest

for

the

discussion

in

Section

4 .

We

found

that

in

a

Winsor

I
syst em

ov er

99.99%

of

the

catalyst

is

located

in

the

microemulsion
phase,

whereas

in

a

Winsor

II

syst em

the

catalyst

is

eq ually
distributed

between

both

phases.
Fig.

4.

Phase

behaviour

of

Marlipal

24/70

in

the

presence

of

different

ligands

(
a

=

50%,

y

=

8%,

1

wt%

sodium

sulfate,

n
Rh(acac)CO
2
=

0.05

mmol,

n
Ligand
=

5

or

10

eq.).
Fig.

5.

Structures

of

the

investigated

ligands.
T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

15 9

Howev er ,

concluding

from

these

results

it

is

clear

that

only
water -soluble

ligands

should

be

used

in

connection

with

three-
phase

microemulsion

syst ems,

if

an

ef fi cient

recy cling

of

the
catalyst

combined

with

a

h ydrophobic

product

isolation

are
desired.
3.4.

T emper ature

in fl uence
The

prior

results

show

that

the

distribution

of

the

rhodium
complex

in

a

microemulsion

syst em

strongl y

depends

on

the
h ydrophobicity

of

the

ligand

and

on

the

kind

of

the

amphiphile.

It
Fig.

6.

Examples

of

catalyst

distribution

obtained

for

the

three

phase

microemulsion

system:

Marlipal

24/70

and

Rh/Xantphos

(left)

and

Marlophen

NP7

and

Rh/SX

(right).
Fig.

7.

Rh-content

in

the

aq ueous

phase

by

the

use

of

different

amphiphiles

(
a

=

50%,

y

=

8%

(
g

=

20%

for

C
4
E
1
and

C
4
E
2
),

1

wt%

sodium

sulfate,

n
Rh(acac)CO
2
=

0.05

mmol,
n
SX
=

5

eq.).
Fig.

8.

Distribution

of

the

Rh

catalyst

for

different

ligands

(
a

=

50%,

y

=

8%

(Marlipal

24/70), 1

wt%

sodium

sulfate,

n
Rh(acac)CO
2
=

0.05

mmol,

n
bidentate
=

5

eq.,

n
monodentate
=

10

eq.).
T able

1
Rhodium

content

in

the

aqueous

phase

at

different

temperatures

with

the

amphiphile

C
4
E
2
(
a

=

50%,

y

=

20%,

1

wt%

sodium

sulfate,

n
Rh(acac)CO
2
=

0.05

mmol

( m
Rh
=

514 5

mg),
n
SX
=

5

eq.)
T emperature

(

C)

Volume

aqueous

lay er
(mL)
Volume

middle

lay er
(mL)
Volume

oil

lay er
(mL)
Rh-concentration

aqueous

lay er
(ppm)
Rh-content

aqueous

lay er

(mg)
60

1 6.0

1 0.4

24.6

34.5

0.55
70

17. 0

9.0

25.0

52.7

0.90
80

17. 0

8.0

26.0

60.3

1 .03
16 0

T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

is

well

known

that

the

temper ature

shows

a

tremendous

in fl uence
on

the

partition

coef fi cient

of

salts

like

the

catalyst

complex.
Hence,

we

investigat ed

the

rhodium

content

in

the

aqueous

phase
at

different

temper atures

(see

T able

1 ).

Since

most

of

the

syst ems
are

extrem ely

temper ature

sensitive,

we

decided

to

choose

the
microemulsion

syst em

formulated

with

of

the

amphiphile

C
4
E
2
.

As
illustrat ed

in

Fig.

2

it

has

a

broad

three

phase

region,

which

allows
us

to

study

the

effect

of

temper ature

without

changing

other
experimental

conditions.
The

results

listed

in

T ab.

1

state

that

the

temperatur e

has

a
strong

in fl uence

on

the

distribution

of

the

catalyst

comple x.

The
results

are

comparable,

because

the

volume

of

the

three

lay ers
stays

almost

constant.

There

is

only

a

small

reduction

of

the

middle
phase

due

to

the

fact

that

the

solubility

of

the

amphiphile

in

the

oil
phase

increases

with

increasing

temper ature.

Hence,

the

volume

of
the

oil

phase

increases

and

that

of

the

middle

phase

decreases.
Howev er ,

we

can

clearly

show

that

the

rhodium

content

in

the
aq ueous

lay er

is

a

function

of

the

temper ature.

The

higher

the
temper ature,

the

higher

is

the

rhodium

content

in

the

aqueous
lay er .

The

amount

of

rhodium

wa s

almost

doubled

by

increasing
the

temper ature

from

33 3

K

to

353

K.

The

results

verify

the

typical
properties

for

the

solubility

of

a

salt.

Most

salts

(the

w ater -soluble
catalyst

complex

is

an

organic

salt)

show

an

increasing

solubility

in
wate r

with

temperatur e.

Thus,

the

separation

temperatur e

is

also
an

important

factor

besides

the

kind

of

amphiphile

and

ligand

to
obtain

a

quantitativ e

recy cling

of

the

catalyst

complex.
3.5.

Tr ansfer

of

the

lab

results

to

a

continuous

process
The

experimental

results

for

the

distribution

of

homogeneous
catalyst

comple x es

in

microemulsion

syst ems

in

the

fi rst

part

of
this

contribution

demonstrate

sever al

possibilities

to

tune

a
reaction

syst em

with

respect

to

an

optimal

cataly st

recy cling
and

separation

process.

The

inter actions

between

the

surfactant
and

the

catalyst

comple x

in fl uence

the

solubility

of

the

latter

and
thus

enable

the

control

of

catalyst

distribution

in

the

different
phases

by

the

choice

of

surfactant.

For

a

fi xed

microemulsion
syst em

the

application

of

different

ligands

has

a

strong

in fl uence
on

the

distribution

of

the

catalyst

complex

as

well.

How ever ,

a
change

of

the

applied

ligand

is

rather

unusual

for

an

established
reaction

process

and

may

result

in

a

modi fi cation

of

the

reaction
kinetics.

Therefore,

the

adjustment

of

the

catalyst

distribution

by
the

choice

of

surfactant

and

the

determination

of

the

optimal
temperatur e

range

for

the

phase

separation

of

the

applied
microemulsion

syst em

should

be

the

preferred

option

for
optimization

of

catalyst

recy cling.
In

order

to

establish

a

closed

recy cle

catalytic

process,

the
Winsor

III

syst em

is

of

great

interest

due

to

its

two

ex cess

phases
allowing

for

separation

of

h ydr ophobic

products

and

h ydrophilic
side-products

in

the

same

separation

step.

Since

the

phase
separation

req uires

a

certain

amount

of

time

depending

on

the
state

and

temper ature

of

the

syst em,

the

reaction

and

cataly st
recy cling

should

be

performed

in

different

process

steps

to

enable
a

continuous

process.
Process

design

for

homogeneous

catalysis

and

catalyst

reco very
in

microemulsion

syst ems

enables

new

paths

in

chemical
engineering.

Ex emplarily ,

the

homogeneousl y

catalysed

conver -
sion

of

long

chained

ole fi ns

becomes

feasible,

as

the

surfactant
compensates

the

miscibility

gap

between

the

ole fi n

and

a

cataly st
solv ed

in

an

aq ueous

phase.

As

part

of

the

Collaborative

R esearch
Center/T ransr egio

63,

“ Integr ated

Chemical

Processes

in

Liq uid
Multiphase

Systems ”

(InPROMPT)

such

a

novel

process

concept

is
being

inv estigated.

One

aim

is

to

design,

construct,

and

operate

a
mini-plant

for

the

continuous

h ydroform ylation

in

such

a
multicomponent

syst em.

Primary

target

is

the

combined

homo-
geneous

catalysis

and

catalyst

reco very

using

this

multiphase
surfactant

syst em.

In

the

following,

the

task,

the

constraints,

and
the

applied

syst em

is

presented

as

well

as

an

actual

application

in
the

mentioned

mini-plant.
3.6.

T ask

formulation
The

task

is

to

design

a

process

in

which

the

catalyst

is

recy cled
reliably

in

order

to

be

reused

in

the

reaction

step

and

leaching

via
product

streams

is

minimized

or

even

eliminated.

After

the
determination

of

a

suitable

tuned

micellar

solv ent

system,

arising
process

constraints

in

terms

of

remaining

catalyst

leaching,
catalyst

stability ,

and

separation

dynamics

ha ve

to

be

outlined,
leading

to

the

development

of

separation

unit

design

for

the

given
task.

To

keep

things

focussed,

we

consider

that

the

product

is
alway s

an

oily

component,

thus

forming

the

upper

ex cess

phase,
and

that

the

cataly st

complex

is

h ydrophilic.

Howeve r ,

parts

of

the
metal

comple x

structure

could

be

h ydr ophobic

and

thus

inducing
side

effects,

which

ha ve

to

be

considered

for

the

separation

step.
The

thermomorphic

behaviour

of

the

microemulsion

syst em

and
the

catalyst

behaviour

described

in

Section

3

are

summarized

in
Fig.

9.

Catalyst

distribution

and

formed

exce ss

phases

in

the

different

phase

separation

systems

for

a

microemulsion

system

tuned

tow ards

oily

product

separation

and
h ydrophilic

catalysts.

Blue:

aqueous

exce ss

phase,

yellow :

oily

exce ss

phase.

The

cy cle

indicates

the

location

of

the

h ydrophilic

catalyst

complex.

(For

interpretation

of

the
references

to

colour

in

this

fi gure

legend,

the

reader

is

referred

to

the

web

version

of

this

article.)
T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

16 1

Fig.

9 ,

showing

the

main

catalyst

position

in

the

described

Winsor
syst ems,

as

well

as

formed

ex cess

phases.
We

assume

that

the

corresponding

phase

shows

the

ma jor
catalyst

concentration

Howev er ,

small

amounts

of

catalyst

could
still

remain

in

the

directly

neighbouring

phases.

The

starting

point
for

the

separation

process

is

right

after

a

reaction

step,

in

which

a
homogeneous

emulsion

is

creat ed.
3.6. 1 .

Phase

separ ation

dynamics
An

important

issue

which

has

to

be

considered

in

terms

of
operation

conditions

and

eq uipment

sizing

(costs)

is

that

of

the
phase

separation

dynamics.

In

the

e xample

shown

in

Fig.

10

the
dependence

of

the

separation

time

t
sep
on

the

temper ature

can

be
seen.

Fortunately ,

the

Winsor

III

state

show s

a

fast

phase
separation

as

opposed

to

the

other

states.

This

means,

a

short
residence

time

in

the

separation

step

is

possible.

F rom

an

economic
point

of

view

this

means

a

smaller

settler ,

the

operation

unit

in
which

the

phase

separation

will

take

place,

can

be

built

or

the
through-put

can

be

increased.

Outside

of

the

Winsor

III

temper a-
ture

interv al

the

separation

time

increases

drastically .

For

the
applied

syst em,

a

separation

in

the

Winsor

I

or

Winsor

II
temperatur e

interv al

was

not

observed,

even

after

several

hours.
Other

experimental

results

as

well

as

a

discussion

on

this

issue
regarding

process

applicability

can

be

found

in

[1 9] .
3.6.2.

Process

constraints
In

addition

to

the

determination

of

catalyst

distribution

and

the
overal l

phase

separation

dynamics,

process

constraints

depending
on

the

applied

substances

and

microemulsion

syst em

need

to

be
speci fi ed.
To

maintain

a

viable

lifetime

of

the

active

catalyst

species

in

a
continuous

process,

operation

temper atures

should

be

low ,

as

the
ligand-metal-complex

is

likely

to

decompose

or

initiate

v arious
side

reactions

at

too

high

temperatur es.

This

implies

limitations

for
applicable

thermal

separation

processes

or

prev ents

for

e xample
the

use

of

distillation

steps,

as

the

catalyst

comple x

would

be
completely

deactiv ated

and

mainly

transformed

into

metal
particles

in

the

reboiler .

The

system

pressure

should

be

kept
constant

or

shifted

smoothly

for

the

overal l

process.

F ailing

that,
irreversible

clustering

of

the

metal-comple xes

may

be

observed,

as
shown

in

inv estigations

of

[20] .

Moreo ver ,

aspects

of

chemical
stability ,

such

as

degradation

through

the

presence

of

oxy gen,

as
well

as

electro

chemical

stability

of

the

catalyst

complex

ha ve

to

be
considered.

R egarding

the

formation

and

thermomorphic

behav -
iour

of

microemulsions,

a

variety

of

side

effects

could

in fl uence

the
separation

dynamics

[9] .

It

is

ob vious

that

for

the

surfactant
concentration

certain

upper

and

low er

bounds

are

req uired

to
maintain

a

microemulsion

syst em.

Impurities

(salts)

cause

shifts

in
the

observed

temperatur e

domains

of

the

emulsion

syst ems,

as
shown

by

Pfennig

et

al.

[2 1] .

Additionally ,

process

pressur e,

stirrer
speed

in

the

react or ,

and

in

gener al

the

occurring

chemical
reactions

in fl uence

the

phase

separation

dynamics

and

feasible
temper ature

domains

for

the

separation

[1 9] .
The

previous

fi ndings

are

summarized

in

Fig.

11 ,

which

outlines
feasible

operation

conditions

and

critical

aspects

of

the

phase
separation

states.

At

this

point

we

de fi ne

a

critical

rhodium

loss,
the

rhodium

mass

fraction

within

the

oil

phase,

which

exits

the
plant

as

a

product

stream.

Considering

only

rhodium

precursor
prices

as

catalyst

costs,

a

value

of

0. 1

ppm

eq uals

monthly

costs

of
around

20 0,0 0 0

for

the

catalyst

(Rhodium

price

of

287

/g

[22] ,
industrial

scale

product

stream

10

t / h ).

This

underlines

the
necessity

for

a

low

rhodium

loss.

Accor ding

to

the

catalyst
distribution

in

the

Winsor

syst em,

the

Winsor

II

state

is

highly
economical

infeasible,

as

high

rhodium

leaching

would

occur .
Additionally ,

the

separation

dynamics

are

expected

to

be

very

slow ,
impairing

the

productivity

of

the

plant.

This

fact

also

ex cludes

the
Winsor

I

system

for

operating

points

of

a

separator

unit,

because
massively

large

units

with

high

residence

times

would

be
necessary ,

although

the

rhodium

loss

poses

to

be

optimall y

low .
Therefore,

only

the

Winsor

III

syst em

seems

economically

feasible,
concerning

both

criteria

and

is

in

scope

for

separator

unit

design
and

operating

conditions.
3.7.

Application

example
The

general

process

concept

is

depicted

in

Fig. 1 2

and

consists

of
2

main

unit

operations:

mixing

and

settling.

In

the

mixer

part,

the
ole fi n,

the

surfactant,

and

an

aq ueous

catalyst

solution

are

mix ed.
By

introducing

syngas

into

the

syst em,

the

h ydr oform ylation
reaction

is

initiated,

thus

forming

aldeh ydes

and

byproducts

[23] .
Afterw ards

the

reaction

media

is

heated

or

cooled

down

to

a
desired

temperatur e

and

separated

accordingly .

The

idea

is

to
exploit

the

thermomorphic

beha viour

and

catalyst

distribution
according

to

Figs.

1

and

9 .

The

goal

is

to

obtain

a

catalyst-fr ee

oil
phase,

in

which

the

product

can

be

found,

and

a

mix ed

phase,
containing

the

v ast

ma jority

of

the

dissolv ed

catalyst.

The

mixed
0
1
2
3
4
5
6
7
8
9
10
65

67

69

71

73

75

77

79
Separ ation time t Sep [min]
Te m p e r a t u r e

T [ ° C]
W insor II

I
W insor

I W insor

II
∞
Fig.

10 .

T emperature

dependency

of

the

phase

separation

time

and

occurring

phase

states

of

a

microemulsion

system

consisting

of

1-dodecene/water/M arlipal

24/70
(
a

=

50%,

y

=

8%,

1

wt%

sodium

sulphate,

n
Rh(acac)CO
2
=

0.05

mmol,

n
SX
=

5

eq.).
16 2

T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

phase

is

then

recy cled,

thus

enabling

the

reuse

of

catalyst

and
surfactant

mixture.
For

the

investigat ed

reaction

system

the

h ydr ophilic

catalyst
comple x,

consisting

of

the

rhodium

precursor

Rh(acac)(CO)
2
and
the

ligand

SulfoXantphos,

is

applied.

Hamerla

et

al.

[1 2]

hav e
shown

that

with

this

comple x

good

reaction

rat es

as

well

as

a

high
selectivity

regarding

the

linear

aldeh yde

are

achiev able.

Moreo ver ,
the

application

of

a

suitable

surfactant

is

outlined,

whereby
according

to

experimental

data

the

use

of

Marlipal

24/7 0

is
Fig.

11 .

Qualitative

evaluation

of

the

rhodium

loss

via

the

product

phase

and

the

economic

feasibility

of

a

settler

operation

in

the

corresponding

Winsor

systems.

Phase
separation

dynamics

are

considered

for

the

feasibility

evaluation.
Fig.

12 .

Process

concept

for

the

h ydroform ylation

of

long-chained

aldeh ydes

in

microemulsion

systems

[24] .
Fig.

13 .

General

mixer -settler

setup

for

the

separation

of

up

to

three

liquid

phases.
T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

16 3

preferential

due

to

its

applicability

for

the

reaction

and

separation
purposes

[25] .
3.8.

Separ ation

unit

design

and

experimental

data
Focussing

on

the

separation

step,

the

results

from

the

fi rst

part
of

this

contribution,

together

with

outlined

process

constraints
and

challenges

are

applied

for

a

separation

unit

design.

Opera-
tional

and

economic

aspects

are

then

discussed

on

basis

of
experimental

data

of

the

respectiv e

unit.
3.8. 1 .

Settler

dev elopment
The

pre-setting

of

a

thermomorphic

multiphase

syst em,
containing

an

oily

component,

w ater ,

and

a

surfactant

for

the
regarded

application

offers

the

exploitation

of

suitable

phase
states.

Due

to

the

density

differences

of

the

components,

a
separation

of

the

emulsion

takes

place

in

a

composition

dependent
temperatur e

domain,

forming

the

three

de fi ned

phases.
F ast

phase

separation

dynamics

for

the

Winsor

III

state

and

a
suitable

catalyst

distribution

(see

Figs.

10

and

11 )

with

almost

no
catalyst

located

in

the

oily

product

could

be

used

in

a

simple

settler
setup.

With

the

knowledge

of

the

component

concentration

range
in

the

react or

outlet

and

corresponding

useful

separation

temper -
atures,

we

propose

a

temper ature

controlled

settler

setup,
depicted

in

Fig.

13 ,

for

which

the

desired

phase

behaviour

could
be

easily

achieved.

In

this

case

a

cylindrical

tank

with

heating
jacket,

feed

inlet,

and

3

outlets

for

the

corresponding

phases

is
applicable.

Adjusting

the

residence

time

via

fl ow

controllers

and
pumps

and

controlling

the

separation

temper ature,

a

phase

split
could

be

realized,

gaining

a

pure

oily

product

stream

at

the

upper
settler

outlet.

Lacking

the

input

of

mechanical

and

large

quantities
of

thermal

energy ,

along

with

needed

internal,

this

set

up

offers
low

investment

and

operational

costs.
In

[1 9]

a

work fl ow

is

presented

on

how

to

syst ematically
analyse

surfactant

containing

multiphase

syst ems

regarding

their
applicability

for

mix er -settler

processes.

With

respect

to

opera-
tional

criteria,

controllability

and

modularization

a

settler
construction

is

present ed,

which

was

realised

and

integrat ed

in
the

regarded

mini-plant.
3.8.2.

Settler

oper ation
Given

a

settler

design,

as

well

as

a

speci fi c

microemulsion
syst em,

the

economic

and

operational

feasibility

has

to

be
validated.

Therefore,

experimental

results

of

a

mini-plant

run

will
be

discussed

in

this

section.

Additional

information

about

the
h ydroform ylation

mini-plant

operation

is

given

by

Müller

et

al.
[26] .
The

operating

point

for

the

reaction

step

of

the

h ydro-
form ylation

in

microemulsions

was

set

to

a

pressure

of

15

bar
(g),

temper ature

of

95

C

and

a

composition

of

a

=

50%,

y

=

8%,

w
Rh
(acac)CO
2
=

298

g/g

w
SX
=

450 0

g/g,

using

Marlipal

24/70

as

a

technical
grade

surfactant.

The

plant

wa s

operated

mostly

in

steady

state
condition

(residence

time

settler

appro x.

40

min),

using

a

settler
with

no

internals.
For

the

observation

of

the

phase

separation

state,

samples

at

the
outlet

of

the

upper

oily

phase

and

the

lower

w ater

phase

were
taken

and

analysed

using

of fl ine

gas

chromatogr aph y .

T aking

a
closer

look

at

Fig.

14 ,

it

is

possible

to

identify

time

periods

where
the

separation

was

adeq uately .

This

is

shown

by

the

sum

of

the
mass

fraction

of

oily

components,

which

reaches

v alues

close

to
10 0 %

for

the

oily

phase

and

simultaneously

low

v alues

in

the

water
phase.

However ,

due

to

concentration

shifts,

caused

by

the

ongoing
reaction,

the

phase

separation

was

partly

lost.
It

has

to

be

mentioned

that

for

the

case

of

equal

mass

fractions
in

oil

and

wate r

phase

basically

no

separation

took

place

and

large
amounts

of

surfactant

and

catalyst

solution

are

introduced

into

the
oil

outlet

stream.

The

ov erall

high

oil

concentrations

in

both

phases
at

these

points

indicate

tempor ary

shifts

in

the

oil

content

of

the
settler ,

caused

by

inappropriate

recy cle

ratios.

By

adjusting
relev ant

process

parameters,

as

temper ature,

recy cle-ratio

and
surfactant

concentration,

the

re-establishment

of

the

separation
was

achieved,

showing

feasible

settler

operation

for

different
operational

states

of

the

mini-plant.
In

addition,

Fig.

15

depicts

the

mass

fraction

of

rhodium

in

the
oil

outlet

stream

of

the

settler .

As

this

is

the

product

stream,

high
rhodium

contents

cause

a

high

economic

loss.
Assuming

a

critical

rhodium

fraction

of

0. 1

ppm

related

to

the
oil

phase,

feasible

operation

periods

are

shown.

For

established
phase

separation,

identi fi ed

by

a

signi fi cant

difference

in

the

oil
content

of

the

regarded

phases

( Fig.

14 ),

rhodium

contents

below
0.05

ppm

wer e

achieved

(Operation

time

35 – 60

h).

With

lost

phase
separation

within

the

ne xt

5

h

of

operation,

the

rhodium

fraction
increases

immediately .

R eferring

to

the

sampling

point

for
operation

time

63

h

this

behaviour

is

indicated

and

even

higher
rhodium

contents

are

expected

in

the

period

of

totally

lost

phase
separation.

Given

the

plant

data,

it

could

be

seen

that

concentra-
tion

shifts

led

to

a

drift

to wards

the

Winsor

I

state,

where
separation

time

increase

massively .

Inter estingly

no

signi fi cant
0
10
20
30
40
50
60
70
80
90
100
35

40

45

50

55

60

65

70

75

80

85
Mass fr action w oil [wt.%]
Operation

time [h]
Oil p

hase
Wate

r ph as e
Fig.

14 .

Mini-plant

operation

data:

mass

fraction

of

total

oily

components

in

the

upper

oily

phase

and

lower

water

phase.
16 4

T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

decrease

of

rhodium

concentration

was

achieved

with

re-
established

phase

separation

(70 – 80

h).

In

this

case

the

settler
temper ature

wa s

set

to

high

and

the

syst em

mov ed

to wards

the
Winsor

II

state,

whereas

phase

separation

slow ed

down

again

and
was

subsequently

lost.
Concluding,

it

is

ob vious

that

the

expect ed

behaviour

for

the
catalyst

distribution

and

phase

separation

dynamics

is

successfully
con fi rmed

in

a

mini-plant

operation.

How ever ,

challenges

still
exist

to

control

the

phase

separation

throughout

all

operational
states

and

under

process

disturbances.

For

these

cases

different
options

for

an

advanced

process

concept

seem

possible

and

are

in
the

scope

of

future

investigations.

Among

these

are

liq uid – liquid
extraction

for

catalyst

and

surfactant

separation

from

an

oily

phase
or

micellar

enhanced

ultra fi ltr ation

techniq ues,

as

described

in
[2 7 ,28] .
4.

Conclusions
The

aim

of

this

contribution

wa s

to

analy se

the

effects

that

can
ha ve

an

in fl uence

on

the

distribution

of

homogeneous

catalyst
comple xes

between

the

different

phase

lay ers

of

microemulsion
syst ems

to

ensure

an

ef fi cient

catalyst

recy cling

for

processes
applying

these

multiphase

systems.

A

profound

knowledge

of

the
thermodynamics

of

microemulsion

systems

and

their

phase
behaviour

as

a

function

of

temper ature

and

composition

is
necessary

to

get

a

quantitati ve

separation

of

the

expensiv e

catalyst
comple x.

Especially

the

three-phase

region

is

of

great

interest

for

a
mix er -settler

process

due

to

its

two

ex cess

phases

allowing

for
separation

of

h ydrophobic

products

and

h ydrophilic

side-products
in

the

same

separation

step.

We

ha ve

shown

that

the

distribution
of

catalyst

in

a

microemulsion

system

can

be

manipulated

by

the
choice

of

the

surfactant,

the

applied

ligand,

and

the

temperatur e.
The

surfactant

seems

to

attract

the

cataly st

comple x,

which

follow s
the

surfactant

into

the

corresponding

microemulsion

phase.
Howev er ,

the

higher

the

h ydrophilicity

of

the

ligand,

the

higher
is

the

amount

of

cataly st

that

remains

in

the

aqueous

phase.

In
contrast,

catalyst

complex es

involving

h ydr ophobic

ligands

stay
almost

in

the

oil

phase

and

should

not

be

used

in

the

presence

of
h ydrophobic

reactants

as

the

separation

is

more

challenging

and
req uires

further

process

steps.

In

addition,

an

increase

of
temper ature

improves

the

solubility

of

the

catalyst

complex

in
the

aq ueous

phase

as

well.

In

summary ,

these

results

establish

the
base

for

integrat ed

processes

using

microemulsion

syst ems.

We
presented

a

case

study

for

the

design

of

a

continuous

mix er -settler
process,

realized

in

a

mini-plant

for

the

Rh/SX

catalysed

h ydr o-
form ylation

of

1-dodecene

to

tridecanal

in

a

microemulsion
syst em.

Analy sing

operation

data,

a

temperatur e

controlled

settler
is

shown

to

be

a

feasible

concept

for

a

separation

step,

gaining

an
oily

product

phase

and

recy cle

a

v aluable

cataly st

rich

phase.

Due
to

disturbances,

temporary

high

rhodium

losses

ha ve

to

be

tackled.
Here,

different

process

options

like

liq uid – liquid

extraction

and
membrane

processes

exist,

which

are

of

future

research

interest.
How ever ,

summarizing

the

existing

options

for

manipulating

the
phase

behaviour

of

the

microemulsion

system

for

the

application
example,

maintaining

the

three

phase

condition

is

desirable

due

to
bene fi cial

separation

dynamics

and

moderate

rhodium

losses.
R egarding

microemulsion

syst ems

in

general,

this

contribution
gives

information

for

a

reasoned

tailoring

of

the

component
syst em

for

an

optimal

catalyst

distribution

within

the

syst em,
where

a

catalyst

rich

aqueous

phase

and

fast

separation

dynamics
is

the

desired

situation

for

an

easy

and

quantitativ e

cataly st
recy cling.
Ackno w ledgements
This

work

is

part

of

the

Collaborative

R esearch

Centre
“ Integr ated

Chemical

Processes

in

Liquid

Multiphase

Systems ”
coordinated

by

the

T echnische

U niversität

Berlin.

Financial

support
by

the

Deutsche

Forschungsg emeinschaft

(DFG)

is

gratefully
acknow ledged

(TRR

63).
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Cornils,

J.

Hibbel,

W.

Konkol,

B.

Lieder ,

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Much,

V.

Schmidt,

E.

Wiebus,
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Zur

Herstellung

von

Aldeh yden

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P .B.

W ebb,

M.F .

Sellin,

T .E.

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S.

Williamson,

A.M.Z.

Slawin,

D.J.

Cole-
Hamilton,

J.

Am.

Chem.

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L.

Leclercq,

I.

Suisse,

F.

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[4]

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Leitner ,

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Fehrmann,

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Volovy ch,

M.

Schwarze,

T.

Hamerla,

J.

Blum,

R.

Schomäcker ,

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Mol.

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A
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(20 1 3)

359 .
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M.

Schwarze,

T.

Pogrzeba,

I.

Volovy ch,

R.

Schomäcker ,

Catal.

Sci.

T echnol.

5
(20 1 5)

24 .
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0
10
20
30
40
50
60
70
80
90
100
35

40

45

50

55

60

65

70

75

80

85
Ma ss fraction w oil [wt.%]
Operation

time [h]
Oil phas e
Rho

di um
Mass fracon Rhodiu m w
Rh

[ppm]
Fig.

15 .

Mini-plant

operation

data:

mass

fraction

of

total

oily

components

(educt,

products)

in

the

upper

oily

phase

and

mass

fraction

of

rhodium

in

the

oily

phase

(product
stream).

Rhodium

was

measured

using

ICP-OES

with

a

Varian

ICP-OES

71 5

ES

instrument,

oil

component

data

was

gathered

from

gas

chromatograph y .
T.

Pogrzeba

et

al.

/

Chemical

Engineering

and

Processing

99

(20 1 6)

15 5 – 16 6

16 5

[1 0]

J.S.

Milano-Brusco,

M.

Schwarze,

M.

Djennad,

H.

Nowot hnick,

R.

Schoma cker ,
Ind.

Eng.

Chem.

Res.

47

(20 08)

7586 .
[1 1]

H.

Nowo thnick,

J.

Blum,

R.

Schomäcker ,

Angew .

Chem.

Int.

Ed.

Engl.

50

(20 1 1)
19 18 .
[1 2]

T.

Hamerla,

A.

Rost,

Y.

Kasaka,

R.

Schomäcker ,

ChemCatChem

5

(20 1 3)

1 854 .
[1 3]

R.

Schomäcker ,

M.

Schwarze,

H.

Nowo thnick,

A.

R ost,

T.

Hamerla,

Chem.

Ing.
T ech.

83

(20 1 1)

1 .
[1 4]

M.-J.

Schwuger ,

K.

Stickdorn,

R.

Schomäcker ,

Chem.

Rev.

95

(1 995)

849 .
[1 5]

M.

Kahlweit,

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Lessner ,

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PAPER 2
Verteilungs gleichgewichte von Ligan den in mizellar en
Lösungsmittelsy stemen
Marcel Schmidt, Tobi a s Pogrzeba, Dmitrij Stehl, René Sachse, Michael
Schwarze, Regine von Klitzin g , Reinhard Schomäcker
Chemie Ingenieur Technik, 2016, 88, 119 -127

Online Article:
http s://o nlinelibrary.wiley.com/doi/full/10.1002/cite.201500125

Reprinted wi th permission from “Verteilungsgleichgewichte von L iganden in
mizellaren Lösungsmittelsystemen; Marcel Schmidt, Tobias Pogrzeba, Dmitrij
Stehl, René S achse, Michael Schwarze, Regine von Klitzing, and Reinhard
Schomäcker. Chemie I ngenieur Technik , 2016, 88, 119-127.“ Copyrigh t (2016)
Wiley-VCH.

V erteilungsgleichgewichte von Liganden
in mizellaren Lo ¨ sungsmittelsystemen
Marcel Schmidt
1,
*, T obias Pogrezba
1
, Dmitrij Stehl
1
, Rene
´ Sachse
1
, Michael Schwarze
2
,
Regine von Klitzing
1
und Reinhard Schoma ¨ cker
1
DOI: 10.1002/cite.201500125
Herrn Prof. Dr .-Ing. Matthias Kraume zum 60. Geburtstag gewidmet
Im Rahmen des Sonderforschungsbereichs SFB/TRR 63 ,,InPROMPT‘‘ (Integrierte chemische Prozesse in flu
¨ ssigen Mehr -
phasensystemen) wird der Einsatz mizellarer Lo ¨ sungsmittelsysteme als schaltbare mehrphasige Reaktionsmedien fu
¨ r die
homogene Katalyse untersucht. In diesem Beitrag wird das V erteilungsgleichgewicht von vier repra ¨ sentativen Liganden in
unterschiedlichen wa ¨ ssrig-mizellaren Systemen analysiert und die Abha ¨ ngigkeit ihrer V erteilung – und damit auch der
eines homogen gelo ¨ sten Katalysators – in den einzelnen Phasen dieser Mehrphasensysteme diskutiert. Die Kenntnis der
V erteilungskoeffizienten ist von entscheidender Bedeutung fu
¨ r eine effiziente und quantitative Katalysatorru
¨ ckfu
¨ hrung in
wa ¨ ssrig-mizellaren Systemen.
Schlagwo
¨ rter: Liganden, Mizellen, T enside, V erteilungskoeffizient
Eingegangen: 14. A ugust 2015; akzeptiert: 29. September 2015
Equilibrium Distribution of Ligands in Micellar Solutions
The applicability of micellar solvent systems as tuneable multiphase reaction media for homogeneous catalysis is being
examined within the framework of the collaborative research centre SFB/TRR 63 ‘ ‘InPROMPT’ ’ (Integrated Chemical Pro-
cesses in Liquid Multiphase Systems). In this contribution the equilibrium distribution of four representative ligands in
different aqueous-micellar systems was investigated and the dependency of their distribution – and thereby the distribu-
tion of a homogeneously dissolved catalyst – in the different phases of these multiphase systems is discussed. The know-
ledge of the distribution coef ficients is of utmost importance for an efficient and quantitative catalyst recycling in aque-
ous-micellar systems.
Keywords: Equilibrium distribution, Ligands, Micelles, Surfactants
1 Einleitung
Fu
¨ r die W irtschaftlichkeit eines chemischen Prozesses in
der homogenen Katalyse ist vor allem die quantitative
Ru
¨ ckfu
¨ hrung der teuren Edelmetall-Katalysatoren von ent-
scheidender Bedeutung. Den Idealfall fu
¨ r homogene Reak-
tionsmedien stellen deshalb sogenannte schaltbare Reak-
tionssysteme dar , deren Phasenverhalten sich zwischen den
verschiedenen Prozessschritten vera ¨ ndern la ¨sst. So sollte ein
Reaktionsmedium wa ¨ hrend der Reaktion homogen sein,
um Stofftransporthemmungen zu vermeiden, und fu
¨ r die
Katalysatorabtrennung in ein Zweiphasensystem umschalt-
bar sein, in dem Produkt und Katalysator in unterschied-
lichen Phasen vorliegen. Zur vollsta ¨ ndigen Abtrennung des
Katalysators vom Produkt empfiehlt sich der Einsatz von
Zweiphasensystemen mit sehr breiten Mischungslu
¨ cken, da
darin die V erteilungskoeffizienten der Katalysatoren ha ¨ ufig
große W erte zugunsten einer der beteiligten Phase anneh-
men. So bieten z. B. wa ¨ ssrig-or ganische Systeme oft optima-
le V erha ¨ ltnisse fu
¨ r die Katalysatorabtrennung, da die Ligan-
den fu
¨ r die Katalysatoren durch funktionelle Gruppen sehr
gut in ihrer Lo ¨ slichkeit (polar/unpolar) eingestellt werden
ko ¨ nnen (s. Abb. 1). Durch einfache Modifikationen am
Liganden (z. B. das Anbringen von Sulfonat-Gruppen zur
Chem. Ing. T ech. 2016 , 88 , No. 1–2, 1 19–127 ª 2016 WILEY -VCH V erlag GmbH & Co. KGaA, W einheim www .cit-journal.com
–
1
Marcel Schmidt ( [email protected] ), T obias Pogrezba,
Dmitrij Stehl, Rene
´ Sachse, Prof. Regine von Klitzing, Prof. Rein-
hard Schoma ¨cker , T echnische Universita ¨ t Berlin, Institut fu
¨ r
Chemie, Straße des 17. Juni 124, 10623 Berlin, Deutschland;
2
Prof.
Michael Schwarze, T echnische Universita ¨ t Berlin, Fachgebiet Anla-
gen- und Sicherheitstechnik, Straße des 17. Juni 135, 10623 Berlin,
Deutschland.
Forschungsarbeit 11 9
Chemie
Ingenieur
Technik

Erho ¨ hung der W asserlo ¨ slichkeit) kann somit dafu
¨ r gesorgt
werden, dass der Katalysator quantitativ in nur einer Phase
vorliegt.
Das Hauptproblem der Anwendung von W asser in der
or ganischen Synthese ist die Unlo ¨ slichkeit vieler Reagenzien
in diesem Medium. Neben zahlreichen Mo ¨ glichkeiten wie
dem Zusatz von hydrophilen Lo ¨ severmittlern, dem Einsatz
von Phasentransfer -Katalysatoren oder pH-Regulierung der
Reaktionslo ¨ sung, bietet der Einsatz von T ensiden eine wei-
tere Option zur Behebung des Lo ¨ slichkeitsproblems. Hier-
bei u
¨ bertragen Mizellen unpolare Reaktanden in die wa ¨ ss-
rige Phase oder polare Komponenten in die organische
Phase. Diese V ariante zur Modifikation von Zweiphasen-
systemen bietet eine hohe Flexibilita ¨ t in ihrer Anwendung,
da eine breite Palette an T ensiden auf dem Markt verfu
¨ gbar
ist. A ußerdem ero ¨ f fnet der Einsatz von T ensiden durch die
Bildung von Mikroemulsionen den Zugang zu schaltbaren
Reaktionsmedien, deren Phasenverhalten stark von der
Zusammensetzung und T emperatur abha ¨ ngig ist.
In den folgenden Kapiteln wird der Einfluss von unter -
schiedlichen Liganden und T ensiden auf die Katalysator-
ru
¨ ckfu
¨ hrung in mizellaren Systemen diskutiert. Fu
¨ r
ausgewa ¨ hlte repra ¨ sentative Liganden wurden die V ertei-
lungskoef fizienten in diesen Systemen experimentell und
rechnerisch ermittelt. A uf Basis dieser Ergebnisse wird die
A ussagekraft der V erteilungskoeffizienten zur V orhersage
der Qualita ¨ t der Katalysatorru
¨ ckfu
¨ hrung in wa ¨ ssrigen
Mehrphasensystemen u
¨ berpru
¨ ft.
2 Grundlagen und Methoden
Fu
¨ r die Bestimmung des polaren Charakters eines Substra-
tes kann der Oktanol/W asser -V erteilungskoeffizient P
OW
,
der nach Gl. (1) definiert ist, herangezogen werden.
P OW ¼ c i
O
c i
W
(1)
In Gl. (1) steht c i
O fu
¨ r die Konzentration des Substrats in
der Oktanolphase und c i
W fu
¨ r die Konzentration in der
W asserphase. Fu
¨ r die Bestimmung des W ertes wird in der
Regel die Shake-Flask-Methode (OECD-Richtline 107) ein-
gesetzt, bei der Oktanol und W asser intensiv gemischt wer-
den, wobei die zu verteilende Substanz in einer der Phasen
vor gelo ¨ st wird. Nach erfolgter Phasentrennung wird die
Konzentration der Substanz in den einzelnen Phasen
bestimmt. Der V orteil der Methode besteht darin, dass die
Phasentrennung zumeist sehr schnell verla ¨ uft und die V er-
suche einfach zu realisieren sind. Fu
¨ r die Bestimmung von
V erteilungskoeffizienten im Allgemeinen existieren aber
auch andere experimentelle Methoden, z. B. u
¨ ber die
Bestimmung von Lo ¨ slichkeiten oder die Flu
¨ ssigkeitschro-
matographie. Eine U
¨ bersicht ist in [1] gegeben. Anstelle der
Konzentrationen kann der V erteilungskoeffizient auch u
¨ ber
die Molenbru
¨ che als K
OW
(Gl. (2)) definiert werden.
K OW ¼ u O
u W
c i
O
c i
W
¼ 6 ; 63 P OW (2)
In Gl. (2) steht u O fu
¨ r das molare V olumen der Oktanol-
phase und u W fu
¨ r das molare V olumen der W asserphase.
Da nach der Phasentrennung die Oktanolphase ca. 28 %
W asser entha ¨lt, wa ¨ hrend die W asserphase nahezu rein
vorliegt, muss dies bei der Berechnung beru
¨ cksichtigt wer -
den, weshalb sich ein V orfaktor von 6,63 ergibt. Neben der
experimentellen Bestimmung der V erteilungskoeffizienten
kann auch eine V orhersage durch Simulationsrechnung
erfolgen. Hierfu
¨ r bietet sich das freiverfu
¨ gbare Programm
ALOGPS2.1 an, das mithilfe ku
¨ nstlicher neuronaler Netze
arbeitet. Dabei werden Modelle fu
¨ r die Lipophilie von che-
mischen Substanzen und die Lo ¨ slichkeit in einer wa ¨ ssrigen
Lo ¨ sung kombiniert, um dies auf unbekannte Stoffe zu u
¨ ber-
tragen. So ko ¨ nnen V erteilungskoeffizienten anhand der che-
mischen Struktur kalk uliert werden – fu
¨ r weitere Infor matio-
nen s. [2]. Dieses Programm eignet sich gut zur V orhersage
der V erteilungsk oef fizienten von nicht-ionisch en V erbindun-
gen, wie z. B. Itaconsa ¨ ureest er [3]. W eiterhin bietet das Pro-
gramm den V orteil, dass auch V erteilungsko ef fizienten
bestimmt werden ko ¨ nnen, wo die experimentelle Erfa ssung
sehr aufwendig ist, z. B. bei Substanzen deren Konzentration
in einer Phase so gering ist, dass sie analytisch kaum erfassba r
ist. Da die V erteilungsko ef fizienten in der Regel u
¨ ber mehrere
Zehnerpote nzen variieren ko ¨ nnen, wird zumeist der log P
OW
bzw . log K
OW
angegebe n.
A uch in T ensidsystemen erfolgt die V erteilung eines Sub-
strats zwischen Doma ¨ nen unterschiedlicher Hydrophobizi-
ta ¨t. Im V ergleich zu den Oktanol/W asser-V erteilungskoeffi-
zienten ist jedoch die experimentelle Bestimmung der
V erteilung in T ensidsystemen aufwendiger , da z. B. fu
¨ r
wa ¨ ssrig-mizellare Lo ¨ sungen oder Mikroemulsionen makro-
skopisch einphasige Systeme vorliegen. W eiterhin ko ¨ nnen
in diesen Systemen, bedingt durch die Anwesenheit des
T ensids, zusa ¨ tzliche Ef fekte die V erteilung stark beeinflus-
sen. Fu
¨ rw a ¨ ssrig-mizellare Lo ¨ sungen findet man in der Lite-
ratur unterschiedliche Methoden zur Bestimmung des V er-
teilungskoeffizienten, die im Folgenden erla ¨ utert werden.
Eine Methode, die sich gut fu
¨ r Feststof fe eignet, ist die
Methode der erho ¨ hten Lo ¨ slichkeit (ESM ; enhanced solu bility
www .cit-journal.com ª 2016 WILEY -VCH V erlag GmbH & Co. KGaA, W einheim Chem. Ing. T ech. 2016 , 88 , No. 1–2, 1 19–127
Abbildung 1. Schematische Darstellung zur V erteilung von
Katalysatoren mit verschiedenen Liganden in einem Flu ¨ ssig/
flu ¨ ssig-Mehrphasensystem.
120 Forschungsarbeit
Chemie
Ingenieur
Technik

method). Dabei steigt die Lo ¨ slichkeit eines Stoffes mit der
T ensidkonzentration aufgrund einer gro ¨ ßeren Anzahl an
Mizellen, die fu
¨ r die Solubilisierung zur V erfu
¨ gung stehen.
W ie in [4] beschrieben, la ¨ sst sich der V erteilungskoeffizient
aus Gl. (3) berechnen.
K MW ¼ S M  S W
ðÞ V W
S W C  cmc ðÞ (3)
In Gl. (3) ist S
M
die Lo ¨ slichkeit des Substrates in der wa ¨ ss-
rig-mizellaren Lo ¨ sung, S
W
die Lo ¨ slichkeit in W asser , C die
T ensidkonzentration, cmc die kritische Mizellbildungskon-
zentration und V
W
das molare V olumen von W asser
(55,55 mol L
–1
). Die Methode ist einfach durchzufu
¨ hren, da
der Bodensatz des nicht gelo ¨ sten Substrates abfiltriert und
nur die gesa ¨ ttigte Lo ¨ sung analysiert wird. Fu
¨ r nicht-ionische
T enside wird oft die T ru
¨ bungspunk textraktio n (CPE; cloud
point ext raction) angew endet. Dabei wird eine, mit dem Sub-
strat gesa ¨ ttigte, wa ¨ ssrig-miz ellare Lo ¨ sung oberhalb der T ru
¨ -
bungstemp eratur in eine wasserreiche und tensidreiche Phase
aufgespal ten. Durch Bilanzier ung der einzelnen Phasen kann
der V erteilungskoef fizient aus Gl. (4) erhalten werden.
K MW ¼ x i
M
x i
W
(4)
In Gl. (4) ist x i
M der Molenbruch des Substrates in der
tensidreichen Phase und x i
W der Molenbruch in der wasser-
reichen Phase. Da die CPE nur fu
¨ r nicht-ionische T enside
geeignet ist, ko ¨ nnen V erteilungen fu
¨ r ionische T enside
damit nicht bestimmt werden. Eine Methode, die fu
¨ r alle
T enside gleichermaßen geeignet ist, ist die Ultrafiltration
wa ¨ ssrig-mizellarer Lo ¨ sungen (MEUF; micellar enhanced
ultrafiltration). Dabei wird eine mit dem Substrat gesa ¨ ttigte,
wa ¨ ssrig-mizellare Lo ¨ sung durch eine Membran mit einem
Porendurchmesser unterhalb der Mizellgro ¨ ße filtriert,
wobei die Mizellen von der Membran zuru
¨ ckgehalten wer -
den. Nur der Anteil an Substrat, der in der kontinuierlichen
W asserphase gelo ¨ st vorliegt, sowie das T ensid in mono-
merer Form passieren ungehindert die Membran. Durch
Bilanzierung des T ensidsystems vor und nach der Filtration
la ¨ sst sich der V erteilungskoeffizient, wie von Schwarze et al.
in [3] gezeigt, bestimmen. Da die experimentellen Metho-
den sehr aufwendig sind, wurden Methoden zur V orhersage
der V erteilungskoeffizienten fu
¨ r T ensidsysteme untersucht.
Eine Methode, die gute V orhersagen liefert, ist COSMO-RS
(conductor-like screening model for real solvents). Diese
Methode konnte bereits anhand von V erteilungskoeffizien-
ten aus CPE [5] oder MEUF [3] validiert werden.
3 Experimentelles
3.1 Chemikalien
Die Lo ¨ sungsmittel 1-Dodecen (94 %) und W asser (HPLC
grade) wurden von VWR bezogen. 1-Oktanol (99 %) wurde
von Roth erhalten. Die technischen T enside Marlipal 24/40,
24/50 und 24/70 sind eine Spende der Firma Sasol. Die T en-
side T riton X-1 14 und T riton X-100, sowie die Liganden
T r iphe ny lpho sp hin ( TP P , 9 9 % ), 4 ,5 -B is(d ip heny lp hosp hi no) -
9, 9- dime thyl xan then e (Xan tP ho s, 97 %) und T ri-( nat rium -
meta-sulfonatophenyl)-phosphan (TPPTS, 95 %) wurden
von Sigma-Aldrich erhalten. Das sulfonierte Analoga zum
XantPhos Ligand, SulfoXantPhos, wurde von der Molisa
GmbH hergestellt. Der Rhodium-V orla ¨ ufer Rh(acac)(CO)
2
ist eine Spende von Umicore. Alle Chemikalien wurden
ohne A ufreinigung verwendet.
3.2 Methoden
Bestimmung des Oktanol/W asser V erteilungskoeffizienten
Zur Bestimmung des Oktanol/W asser -V erteilungskoeffi-
zienten wurden jeweils 5 mL von mit W asser gesa ¨ ttigtem
Oktanol und mit Oktanol gesa ¨ ttigtem W asser gemischt.
Anschließend wurden 100 mg SulfoXantPhos bzw . TPPTS
hinzugegeben und u
¨ ber Nacht auf einer Ru
¨ ttelplatte ver-
mischt. Die Konzentration der Liganden in den einzelnen
Phasen wurde nach der Phasentrennung mit einer HPLC-
Anlage der Serie 1200 von Agilent untersucht. Als Sa ¨ ule
wurde eine Multospher 120 RP18-5 m L verwendet. Die Pro-
ben wurden bei einer Flussrate von 1 mL min
–1
mit einem
Lo ¨ semittelgemisch aus W asser/Acetonitril von 30:70 ver-
messen.
Erho ¨ hte Lo ¨ slichkeitsmethode
Zur Bestimmung des Mizelle/W asser-V erteilungskoeffizien-
ten mittels der Methode der erho ¨ hten Lo ¨ slichkeit (ESM)
wurden verschiedene tensidhaltige Lo ¨ sungen hergestellt
und der zu untersuchende Ligand bis zur Bodensatzbildung
hinzugegeben. Die mizellare Lo ¨ sung wurde u
¨ ber Nacht auf
einer Ru
¨ ttelplatte gemischt, anschließend filtriert und das
Filtrat auf die Konzentration des Liganden analysiert.
Tr u ¨ bungspunkt-Extraktion
Fu
¨ r die T ru
¨ bungspunkt-Extraktion (CPE) wurden 5 Gew .-%
des T ensids mit den zu untersuchenden Liganden in einer
wa ¨ ssrigen Lo ¨ sung gemischt. Die T emperatur wurde schritt-
weise erho ¨ ht, bis der Tru
¨ bungspunkt erreicht wurde. Nach
erfolgter Phasentrennung wurden die einzelnen Phasen
mittels HPLC hinsichtlich der Ligandenkonzentration
untersucht. Fu
¨ r den Liganden XantPhos wurde die Kon-
zentration mittels induktiv gekoppeltem Plasma mit opti-
scher Emissionsspektroskopie (ICP-OES) bestimmt. Fu
¨ r die
analytische Messung wurde das ICP-OES V arian 714 ES
verwendet und zur Kalibrierung wurden Phosphorlo ¨ sungen
mit 1, 10, 100 und 1000 mg L
–1
her gestellt. Die A uswertung
erfolgte bei einer W ellenla ¨ nge von 213 nm.
Bestimmung der Oberfla ¨ chenspannung der Liganden
Die Messungen zur Oberfla ¨ chenspannung der Liganden-
lo ¨ sungen wurden mit einem DCA T 1 1 der Firma
Chem. Ing. T ech. 2016 , 88 , No. 1–2, 1 19–127 ª 2016 WILEY -VCH V erlag GmbH & Co. KGaA, W einheim www .cit-journal.com
Forschungsarbeit 121
Chemie
Ingenieur
Technik

DA T APHYSICS durchgefu
¨ hrt. Der Messko ¨ rper war ein Du
Nou
¨ y-Ring bestehend aus einer Platin-Iridium-Legierung
mit einer Ringho ¨ he von 25 mm, einen Ringdurchmesser
von 18,7 mm und einer Drahtdicke von 0,37 mm. Es wur -
den verschieden konzentrierte Lo ¨ sungen der Liganden
TPPTS und SulfoXantPhos hergestellt und vermessen. Nach
jeder Messung wurde der Messring mit einer Butangas-
flamme gereinigt.
Bestimmung der V erteilung des Katalysators in der
Mikr oemulsion
Die Konzentration von Rhodium in den unterschiedlichen
Phasen eines mehrphasigen Mikroemulsionssystems wurde
mittels ICP-OES bestimmt. Es wurde jeweils die wa ¨ ssrige
Phase und die Mittelphase des Mikroemulsionssystems
untersucht. Dazu wurden 2 mL der wa ¨ ssrigen bzw . 1 mL der
Mittelphase mit Ko ¨ nigswasser versetzt und mit destilliertem
W asser verdu
¨ nnt. Die Rhodiumkonzentration wurde bei
einer W ellenla ¨ nge von 369 nm gemessen. Die Kalibrierung
erfolgte mit Rhodiumstandard-Lo ¨ sungen der Konzentration
1, 5, 20, 50 und 150 mg L
–1
.
4 Ergebnisse und Diskussion
Fu
¨ r die effektive Abscha ¨ tzung der V erteilung von homo-
genen Katalysatorkomplexen in tensidmodifizierten Flu
¨ ssig/
flu
¨ ssig-Mehrphasensystemen spielt die Polarita ¨ t des Kom-
plexes eine entscheidende Rolle. Diese kann maßgebend
durch die Lo ¨ slichkeitseigenschaften des verwendeten Ligan-
den gesteuert werden. Das W issen u
¨ ber die V erteilung des
Liganden ist somit essentiell fu
¨ r die quantitative Abtren-
nung des homogenen Katalysatorkomplexes.
Das V erteilungsgleichgewicht eines homogenen Katalysa-
torkomplexes soll fu
¨ r mizellare Lo ¨ sungsmittelsysteme quali-
tativ vorhergesagt werden, wobei ein besonderes A ugen-
merk auf die Art der Liganden und die Struktur des T ensids
gelegt wird. Dazu wird schrittweise die Komplexita ¨ t des
Flu
¨ ssig/flu
¨ ssig-Mehrphasensystems erho ¨ ht um eine aussage-
kra ¨ ftige Beurteilung zu gewa ¨ hrleisten.
4.1 V erteilungskoeffizienten fu
¨ r verschiedene
Liganden zwischen 1-Oktanol und Wasser
Fu
¨ r die A uswahl eines Katalysatorkomplexes fu
¨ r Flu
¨ ssig/
flu
¨ ssig-Mehrphasensysteme spielt der V erteilungskoeffi-
zient des Liganden zwischen den nicht mischbaren Pha-
sen eine entscheidende Rolle. A uf der einen Seite muss
die lokale Konzentration aller Reaktionsteilnehmer so
hoch sein, dass eine wirtschaftlich sinnvolle Reaktions-
geschwindigkeit resultiert. A uf der anderen Seite muss
sichergestellt werden, dass ein Recycling des ligand-modi-
fizierten, meist teuren Katalysatorkomplexes und eine
T rennung des Reaktionsproduktes durch eine Phasensepa-
ration ermo ¨ glicht wird.
Die V erteilungskoeffizienten von nicht-ionischen Ligan-
den sind fu
¨ r Flu
¨ ssig/flu
¨ ssig-Mehrphasensysteme wie Okta-
nol/W asser bekannt bzw . ko ¨ nnen mit verschiedenen Metho-
den berechnet werden, jedoch findet man kaum
Informationen fu
¨ r ionische Liganden, die sulfoniert und
somit wasserlo ¨ slich sind. Deshalb wurden die Oktanol/
W asser -V erteilungskoef fizienten K
OW
fu
¨ r TPPTS und
SulfoXanthPhos – die sulfonierten Analoga zu TPP und
XantPhos – bestimmt (T ab. 1). Fu
¨ r die Berechnung der V er -
teilungskoeffizienten wurde das Programm ALOGPS2.1
verwendet, das fu
¨ r nicht-ionische und nicht-geladene Mole-
ku
¨ le gute V orhersagen liefert.
Die berechneten Oktanol/W asser -V erteilungskoeffizien-
ten zeigen, dass das bidentate XantPhos im V ergleich zu
TPP viel hydrophober ist, was auf die gro ¨ ßere Anzahl an
Phenylringen zuru
¨ ckzufu
¨ hren ist (Abb. 2). Der berechnete
W ert fu
¨ r TPP stimmt dabei mit dem experimentell ermittel-
ten Literaturwert u
¨ berein. Eine Berechnung fu
¨ r die wasser-
lo ¨ slichen Analoga konnte aufgrund ihres ionischen Cha-
rakters nicht durchgefu
¨ hrt werden. Die experimentellen
Daten zeigen jedoch deutlich, dass die Sulfonierung eine
Umkehrung der Lo ¨ slichkeit hervorruft und TPPTS bzw .
SulfoXantPhos sich vorwiegend in der W asserphase lo ¨ sen.
Dabei zeigt TPPTS im V ergleich zu SulfoXantPhos einen
kleineren Oktanol/W asser -V erteilungskoeffizienten, da drei
www .cit-journal.com ª 2016 WILEY -VCH V erlag GmbH & Co. KGaA, W einheim Chem. Ing. T ech. 2016 , 88 , No. 1–2, 1 19–127
T abelle 1. Experimentelle und berechnete Oktanol-Wasser-V er-
teilungskoeffizienten K
OW
fu ¨ r verschiedene Liganden (berech-
net mit ALOGPS2.1).
Ligand log( K
OW
) exp. log( K
OW
) ber .
TPP 6,02 [6] 6,2 ± 0,5
TPPTS –3,07 –
XantPhos – 1 1,1 ± 1,4
SulfoXantPhos –1,21 –
Abbildung 2. Strukturformeln der Liganden TPP , TPPTS, Xant-
Phos und SulfoXantPhos.
122 Forschungsarbeit
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statt zwei Sulfonat-Gruppen fu
¨ r eine gro ¨ ßere
Hydrophilie im Moleku
¨ l sor gen. A ußerdem
besitzt SulfoXantPhos eine gro ¨ ßere Anzahl an
Phenylgruppen.
4.2 V erteilungskoeffizienten fu
¨ r
verschiedene Liganden in einem
mizellaren Lo ¨ sungsmittelsystem
Ein basiertes W issen u
¨ ber den Mizelle/W asser -
V erteilungskoeffizienten K
MW
ist entscheidend,
um den T rennungsprozess fu
¨ r homogene Kata-
lysatorkomplexe in mizellaren Lo ¨ sungsmittelsys-
temen zu verstehen und das Recycling zu opti-
mieren. Fu
¨ r neutrale, nicht oberfla ¨ chenaktive
Komponenten besteht ein linearer Zusam-
menhang zwischen den Oktanol/W asser- und
Mizelle/W asser -V erteilungskoeffizienten [7], der
durch die Collander-Gleichung [8] beschrieben
werden kann (Gl. (5)). Collander beobachtete in
verschiedenen zweiphasigen Systemen einen
linearen Zusammenhang zwischen den logarith-
mierten V erteilungskoeffizienten einer Kom-
ponente, wobei K
1
und K
2
die V erteilungskoeffi-
zienten in den Systemen 1 und 2 wiederspiegelt
und a und b empirische Konstanten sind.
log ð K 1 Þ¼ a log ð K 2 Þþ b (5)
Jedoch ist dieser Zusammenhang fu
¨ r ionische
Spezies nicht nachweisbar , so dass dort zusa ¨ tz-
liche Effekte bei der V erteilung in einem mizella-
ren Lo ¨ sungsmittelsystem eine wesentliche Rolle
spielen und untersucht werden mu
¨ ssen. Im Fol-
genden wird der V erteilungskoeffizient fu
¨ r einige
Modell-Liganden, die ha ¨ ufig in Metallkom-
plexen eingesetzt werden, diskutiert, wobei ein
A ugenmerk auf die T ensidauswahl sowie auf die
Struktur des Liganden gelegt wird.
4.2.1 T ensideinfluss
Zuna ¨ chst wurde der Einfluss des T ensids auf die V erteilung
des hydrophoben Liganden TPP und des hydrophilen
Liganden SulfoXantPhos untersucht (Abb. 3). Dazu wurden
die nichtionischen T enside NP9, T riton X-100, T riton
X-1 14, Marlipal 24/40, 24/50 und 24/70, und das anionische
T ensid Natriumdodecylsulfat (SDS) verwendet. T ypische
Eigenschaften der T enside sind in T ab. 2 aufgelistet und die
T ensidstrukturen sind in Abb. 4 gezeigt.
Der Mizelle/W asser -V erteilungskoeffizient K
MW
von TPP
liegt in der Gro ¨ ßenordnung von K
OW
fu
¨ r TPP . Demnach
wird TPP vorwiegend innerhalb des hydrophoben Kerns
der gebildeten Mizellen eingelagert. Des W eiteren war die
Struktur des T ensids hinsichtlich des Mizelle/W asser-V ertei-
lungskoef fizienten von Interesse, weshalb zwei T enside mit
identischen Ethoxylierungsgrad, aber unterschiedlichem
hydrophoben Rest verglichen wurden: T riton X-100 besitzt
einen verzweigten hydrophoben Rest und Marlophen NP9
weist eine lineare Alkylkette mit vergleichbarer Kohlenstof f-
anzahl auf. Es wurden bedingt durch die unterschiedlichen
Alkylketten leicht unterschiedliche V erteilungskoeffizienten
bestimmt. Durch die verzweigte Alkylkette ist der Kern der
gebildeten T riton X-100-Mizelle hydrophiler im V er gleich
zu Marlophen NP9. Dadurch ist der V erteilungskoeffizient
geringer , da das stark hydrophobe TPP somit den Kern der
Mizelle von Marlophen NP9 pra ¨ feriert.
W eiterhin wurde der Einfluss des Ethoxylierungsgrad
untersucht, wobei die T enside T riton X-100 (9 – 10
Ethoxyeinheiten) und Triton X-1 14 (7 – 8 Ethoxyeinheiten)
Chem. Ing. T ech. 2016 , 88 , No. 1–2, 1 19–127 ª 2016 WILEY -VCH V erlag GmbH & Co. KGaA, W einheim www .cit-journal.com
Abbildung 3. V erteilungskoeffizienten von TPP (links) und SulfoXantPhos
(rechts) in mizellaren, wa
¨ ssrigen Lo
¨ sungen mit der Methode nach der erho
¨ hten
Lo
¨ slichkeit (ESM) und der Tru ¨ bungspunkt Extraktion (CPE).
T abelle 2. Molare Masse, Tru ¨ bungspunkt, cmc und HLB-Wert der verwendeten
T enside.
T ensid Molare Masse
[g mol
–1
]
Tr u
¨ bungspunkt
[  C]
cmc
[mol L
–1
]
HLB-W ert
T riton X-100 » 625 65 2  10
–4
13,5
T riton X-1 14 » 537 23 2  10
–4
12,4
Marlophen NP9 » 600 52 – 56
a)
6,7  10
–5
–
SDS 288,38 – 8,2  10
–3
40
d)
Marlipal 24/40 » 376 66 – 68
b)
––
Marlipal 24/50 » 420 72 – 74
b)
––
Marlipal 24/70 » 508 53 – 56
c)
––
a) 1 % in deionisiertem Wasser , b) 10 % in 25 % BDG-Lo
¨ sungen, c) 2 % in deioni-
siertem Wasser , d) nach der Methode von Davies.
Forschungsarbeit 123
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mit identischer hydrophober Alkylkette, jedoch unter-
schiedlicher Anzahl an Ethoxyeinheiten verglichen wurden.
Die Schicht der hydrophilen Kopfgruppen von Triton
X-100 ist im V er gleich zu T riton X-1 14 aufgrund der ho ¨ he-
ren Anzahl an Ethoxyeinheiten hydrophiler . Als Folge wird
der Ligand TPP zusa ¨ tzlich aus der kontinuierlichen wa ¨ ss-
rigen Phase verdra ¨ ngt und es resultiert bei T riton X-100 ein
ho ¨ herer V erteilungskoeffizient im V er gleich zu T riton
X-1 14. Fu
¨ r T riton X-100 und den Liganden TPP wurde mit-
tels COSMO-RS ein Mizelle/W asser -V erteilungskoeffizient
von 7,1 bestimmt, der sich zwei Gro ¨ ßenordnungen von den
experimentellen unterscheidet [9]. Der V erteilungskoeffi-
zient fu
¨ r SulfoXantPhos P
MW
, bestimmt durch eine T ru
¨ -
bungspunkt-Extraktion, zeigt eine identische T endenz. Je
hydrophiler das T ensid ist, desto ho ¨ her ist der V erteilungs-
koef fizient. Demzufolge reichert sich SulfoXantPhos, ab-
ha ¨ ngig von der Hydrophilie des T ensids, bevorzugt in der
tensidreichen Phase an, wobei jedoch zusa ¨ tzliche Effekte
eine entscheidende Rolle spielen, die im na ¨ chsten Abschnitt
diskutiert werden. U
¨ berraschend ist dabei der positive
W ert des Mizelle/W asser-V erteilungskoef fizienten, da der
Oktanol/W asser -V erteilungskoeffizient log K
OW
fu
¨ r
SulfoXantPhos stark negativ war . Fu
¨ r T riton X-1 14 ist
exemplarisch gezeigt, dass die gewa ¨hlte Methode fu
¨ r die
Bestimmung des V erteilungskoeffizienten keine Rolle fu
¨ r
das Ergebnis spielt, da sich die log K
MW
-W erte innerhalb
der Messgenauigkeit decken. Zusa ¨ tzlich wurde der Einfluss
eines ionischen T ensids (SDS) auf den V erteilungskoeffi-
zienten von TPP untersucht. Im V ergleich zu den anderen
T ensiden erha ¨ lt man hier einen a ¨ hnlichen V erteilungskoeffi-
zienten wie fu
¨ r TX-1 14. Da TPP keine Ladung tra ¨ gt, kann
nur eine W echselwirkung mit dem hydrophoben Mizellkern
des SDS erfolgen und nicht zusa ¨ tzlich mit den ionischen
Kopfgrupp en. Jedoch kann es zu attraktiv en W echselwirkun-
gen kommen, wenn das Substrat eben falls Ladu ngen tra ¨gt.
A us der W asseraufbereitung mittels mizellgestu
¨ tzter
Ultrafiltration (MEUF) ist bekannt, dass sich Metallionen
an die negativen Kopfgruppen von anionischen T ensiden
anbinden, wodurch aufgrund der vorliegenden Komplexie-
rung der V erteilungkoeffizient zugunsten der Mizelle ver -
schoben wird. Dadurch ko ¨ nnen die Metallionen leicht abge-
trennt werden [10, 1 1]. Dasselbe Prinzip gilt auch fu
¨ r
gelo ¨ ste Anionen und kationische T enside. So wurde in fru
¨ -
heren Arbeiten zur Hydroformulierung von Olefinen in
Gegenwart des kationischen T ensids Cetyltrimethylammo-
niumbromid (CT AB) unter V erwendung des hydrophilen
Liganden TPPTS oft ho ¨ here Aktivita ¨ ten beobachtet, die sich
neben einer ho ¨ heren Eduktkonzentration im Mizellkern
auch durch einen ho ¨ heren V erteilungskoeffizienten von
TPPTS erkla ¨ ren lassen; auch wenn dieser nie bestimmt wur-
de [12].
4.2.2 Ligandeneinfluss
Wa ¨ hrend in Abschn. 4.2.1 gezeigt wurde, dass sich durch
die A uswahl des T ensids Einfluss auf die V erteilung des
Liganden nehmen la ¨sst, wird nun der Einfluss des Liganden
selbst diskutiert. Fu
¨ r die beiden nicht-ionischen T enside
TX-100 und TX-1 14 sind die V erteilungskoeffizienten der
untersuchten Liganden in Abb. 5 gezeigt.
W ie schon zuvor diskutiert, ist bei allen Liganden ein
kleinerer V erteilungskoeffizient bei T riton X-1 14 zu be-
obachten. U
¨ berraschend ist, dass der V erteilungskoeffizient
von XantPhos im V ergleich zu TPP kleiner ist, obwohl K
OW
fu
¨ r XantPhos deutlich u
¨ ber den von TPP liegt. W eiterhin ist
interessant, dass fu
¨ r das wasserlo ¨ slichen SulfoXantPhos ein
experimenteller V erteilungskoeffizient log K
MW
von ca. 2,4
ermittelt wurde. Dies bedeutet, dass SulfoXantPhos vorwie-
gend in oder an der Mizelle eingelagert ist, was in Kontrast
zu den Ergebnissen fu
¨ r K
OW
steht. Erwartungsgema ¨ß h a ¨ tte
www .cit-journal.com ª 2016 WILEY -VCH V erlag GmbH & Co. KGaA, W einheim Chem. Ing. T ech. 2016 , 88 , No. 1–2, 1 19–127
Abbildung 4. Strukturformeln der T enside T riton X-100, T riton
X-1 14, Marlophen NP9, Marlipal 24/40, 24/50 und 24/70 und
SDS.
Abbildung 5. V erteilungskoeffizienten von TPP , XantPhos und
SulfoXantPhos in mizellaren, wa
¨ ssrigen Lo
¨ sungen mit T riton
X-100 und Triton X-1 14, bestimmt mittels ESM.
124 Forschungsarbeit
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auch fu
¨ r den Mizelle/W asser -V erteilungskoeffizienten auf-
grund der Polarita ¨t von SulfoXantPhos ein negativer W ert
resultieren mu
¨ ssen. Jedoch scheinen hier zusa ¨ tzliche Ef fekte
eine entscheidende Rolle zu spielen. Da das Moleku
¨ l Sulfo-
XantPhos a ¨ hnlich wie ein T ensid u
¨ ber einen hydrophoben
und hydrophilen T eil verfu
¨ gt, ist anzunehmen, dass Sulfo-
XantPhos eine oberfla ¨ chenaktive Substanz ist, die somit als
T ensid fungieren kann. Demnach lagert sich SulfoXantPhos,
bedingt durch dessen Oberfla ¨ chenaktivita ¨ t, an der Mizelle
an und es er gibt sich ein ver gleichsweiser hoher Mizelle/
W asser -V erteilungskoef fizient. Dies wird auch durch die
Messung der Oberfla ¨ chenspannung von wa ¨ ssrigen Lo ¨ sun-
gen der Liganden besta ¨ tigt. Die sulfonierten Liganden
SulfoXantPhos und TPPTS zeigen beide oberhalb einer
Konzentration von 1  10
–4
mol L
–1
einen Abfall der Oberfla ¨-
chenspannung (Abb. 6). Dies erkla ¨ rt den großen Mizelle/
W asser -V erteilungskoef fizienten von SulfoXantPhos.
4.3 V erteilung des Katalysatorkomplexes in einem
Mikroemulsionssystem
Die W echselwirkungen zwischen verschiedenen
Liganden und den Komponenten eines mizella-
ren Lo ¨ sungsmittelsystems sind nun weitest-
gehend bekannt. Jedoch erho ¨ ht sich die Kom-
plexita ¨ t des Lo ¨ sungsmittelsystems, wenn ein
hydrophobes Lo ¨ sungsmittel hinzukommt und
eine Mikroemulsion gebildet wird. In Abb. 7
sind schematisch die V erteilungsgleichgewichte
eines homogenen Katalysatorkomplexes zwi-
schen den einzelnen Phasen eines Mikroemul-
sionssystems im Dreiphasengebiet aufgezeigt. Es
wird angenommen, dass die V erteilung des Kata-
lysatorkomplexes vorwiegend durch die Eigen-
schaften der Liganden bestimmt wird.
Durch die zusa ¨ tzliche O
¨ lkomponente spielt nicht nur die
V erteilung des Katalysators zwischen der wa ¨ ssrigen und
tensidreichen Phase, sondern auch die V erteilung zwischen
der tensidreichen und o ¨ ligen Phase eine Rolle. Fu
¨ r eine
quantitative Abtrennung der teuren homogenen Katalysato-
ren ist es somit essentiell, die V erteilungsgleichgewichte zu
kennen bzw . vorhersagen zu ko ¨ nnen. In Abb. 8 ist die
V erteilung des Rhodium-Katalysators fu
¨ r die Liganden
XantPhos und SulfoXantPhos in einem Mikroemulsionssys-
tem dar gestellt. Als T ensid wurde Marlipal 24/70 verwen-
det.
Es ist deutlich zu erkennen, dass die Hydrophilie und
Grenzfla ¨ chenaktivita ¨ t des Liganden entscheidend fu
¨ r die
V erteilung des Katalysatorkomplexes ist. Fu
¨ r den hydropho-
ben Liganden XantPhos ist der Katalysatorkomplex zu 74 %
in der O
¨ lphase enthalten, was auch optisch durch die inten-
sive Rotfa ¨ rbung der O
¨ lphase ersichtlich ist. Der restliche
Anteil befindet sich in der tensidreichen Mittelphase, die
selbst ca. 1/4 der organischen Phase entha ¨ lt. Interessant ist,
dass fu
¨ r den wasserlo ¨ slichen Katalysatorkomplex mit Sulfo-
XantPhos eine klare wa ¨ ssrige Phase vorhanden ist und sich
der Großteil (96,3 %) des Katalysatorkomplexes in der ten-
sidreichen Mittelphase anreichert. Dies ist, belegt durch die
Mizelle/W asser -V erteilungskoeffizienten K
MW
von Sulfo-
XantPhos, auf die attraktiven W echselwirkungen und die
Grenzfla ¨ chenaktivita ¨ t des Liganden mit dem T ensid zuru
¨ ck-
zufu
¨ hren, wodurch der gesamte Katalysatorkomplex in die
Chem. Ing. T ech. 2016 , 88 , No. 1–2, 1 19–127 ª 2016 WILEY -VCH V erlag GmbH & Co. KGaA, W einheim www .cit-journal.com
Abbildung 6. Oberfla
¨ chenspannung s von wa
¨ ssrigen TPPTS-
und SulfoXantPhos-Lo
¨ sungen in Abha
¨ ngigkeit der Konzentra-
tion.
Abbildung 7. Schematische Darstellung des V erteilungsgleich-
gewichtes eines Katalysators in einer Mikroemulsion.
Abbildung 8. V erteilung des Rhodium-Katalysators bei Verwendung von
SulfoXantPhos (links) und XantPhos (rechts) mit dem Tensid Marlipal 24/70 und
1-Dodecen als Lo
¨ sungsmittel ( m
Wasser
= m
1-Dodecen
=2 0 g , m
Marlipal 24/70
= 3,47 g,
1 Gew .-% Natriumsulfat, n
Rh(acac)(CO)2
= 0,05 mmol, n
Ligand
= 5 eq.).
Forschungsarbeit 125
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tensidreiche Mittelphase eingelagert wird. Somit ko ¨ nnen die
Mizelle/W asser -V erteilungskoeffizienten genutzt werden,
um erste Hinweise u
¨ ber die V erteilung von Katalysatorkom-
plexen in einem Mikroemulsionssystem zu erhalten.
Die Er gebnisse fu
¨ r die Anreicherung des Rh/SulfoXanth-
phos-Komplexes in der tensidreichen Phase lassen sich
auch auf einen kontinuierlichen V ersuch in einer Miniplant
u
¨ bertragen, in der 1-Dodecen zu T ridecanal in einem
Mikroemulsionssystem bestehend aus 1-Dodecen, W asser
und Marlipal 24/70 hydroformuliert wurde. Die Phasen-
trennung des Reaktionsgemisches wurde bei der kontinuier-
lichen Prozessfu
¨ hrung von ca. 200 h in einem Dekanter rea-
lisiert. Dabei separierte das Reaktionsgemisch in eine
Produktphase, die abgefu
¨ hrt wurde, und eine katalysator-
reiche Phase, die zuru
¨ ck in den Reaktor gefu
¨ hrt wurde.
U
¨ ber 99,99 % des Katalysators blieben in der Katalysator -
phase im aktiven Zustand erhalten [13]. Die gute Trennung
und hohe Ru
¨ ckfu
¨ hrrate besta ¨ tigen die V orhersagen zur
Katalysatorverteilung auf der Grundlage der V erteilung des
Liganden.
5 Zusammenfassung
Fu
¨ r Flu
¨ ssig/flu
¨ ssig-Zweiphasenreaktionen bieten sich ten-
sidmodifizierte Reaktionsmedien an, da diese nicht nur zu
wirtschaftlich sinnvollen Reaktionsgeschwindigkeiten fu
¨ h-
ren, sondern es auch ermo ¨ glichen, homogene Katalysatoren
vom Produkt abzutrennen und nochmals zu verwenden.
Ein entscheidender Faktor fu
¨ r die quantitative Abtrennung
des Katalysators ist die W ahl eines geeigneten Liganden und
die Art des verwendeten T ensids. Es konnte gezeigt werden,
dass die Struktur und Art des T ensids nur einen geringen
Einfluss auf den V erteilungskoeffizienten von nichtioni-
schen Liganden in einem mizellaren Reaktionssystem hat.
A usschlaggebenden Einfluss auf den V erteilungskoeffizien-
ten in mizellaren Systemen hat nicht nur wie erwartet die
Hydrophobizita ¨ t der Liganden, sondern auch deren Grenz-
fla ¨ chenaktivita ¨t . F u
¨ r grenzfla ¨ chenaktive sulfonierte Phos-
phinliganden konnte gezeigt werden, dass sich diese an die
T ensidphase anlagern, wodurch ein unerwartet hoher
Mizelle/W asser -V erteilungskoeffizient resultiert.
Diese Arbeiten sind T eil des von der TU Berlin
koordinierten Sonderforschungsbereichs/Transregios 63
,,Integrierte chemische Prozesse in flu
¨ ssigen Mehr -
phasensystemen‘ ‘. Die A utoren bedanken sich bei der
DFG fu
¨ r die finanzielle Unterstu
¨ tzung des Projektes
(TRR63).
Formelzeichen
c i
O [mol L
–1
] Konzentration des Substrats i
in der Oktanolphase
c i
W [mol L
–1
] Konzentration des Substrats i
in der W asserphase
cmc [mol L
–1
] kritische Mizellbildungskonzen-
tration
K
OW
[–] V erteilungskoeffizient Oktanol-
W asser , berechnet aus den
Molenbru
¨ chen
K
MW
[–] V erteilungskoeffizient Mizelle-
W asser
m [kg] Masse
n [mol] Stof fmenge
P
OW
[–] V erteilungskoeffizient Oktanol-
W asser , berechnet aus den
Konzentrationen
S
M
[mol L
–1
]L o ¨ slichkeit des Substrats in der
mizellaren Lo ¨ sung
S
W
[mol L
–1
]L o ¨ slichkeit des Substrats
in W asser
V
W
[m
3
mol
–1
] molares V olumen von W asser
x i
M [–] Molenbruch des Substrats i in der
mizellaren Phase
x i
W [–] Molenbruch des Substrats i in der
W asserphase
n
O
[m
3
mol
–1
] molares V olumen der
Oktanolphase
n
W
[m
3
mol
–1
] molares V olumen der
W asserphase
s [mN m
–1
] Oberfla ¨ chenspannung
Abku ¨ rzungen
BDG 2-(2-Butoxyethoxy)ethanol
COSMO-RS conductor-like screening model for real
solvents
CPE T ru
¨ bungspunkt-Extraktion
CT AB Cetyltrimethylammoniumbromid
ESM erho ¨ hte Lo ¨ slichkeitsmethode
HLB hydrophilic-lipophilic balance
ICP-OES Optische Emissionsspektrometrie mit
induktiv gekoppeltem Plasma
ME Mikroemulsion
MEUF micellar enhanced ultrafiltration
OECD Organisation for Economic Cooperation and
Development
SDS Natriumdodecylsulfat
TPP T riphenylphosphin
TPPTS T ri-(natrium-meta-sulfonatophenyl)-
phosphan
XantPhos 4,5-Bis(diphenylphosphino)-9,9-dimethylxan-
thene
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126 Forschungsarbeit
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Ingenieur
Technik

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PAPER 3
Hydroformylati on in micr oemulsions: Proof of concept in a
miniplan t
Markus Illn er and David Müller, Erik Esche, Tobias Pogrzeba, Marcel Schmidt,
Reinhard Schomäcker, Günter Wozny, Jens-Uwe Repke
Indu stria l & Engineering Chemistry Rese arch, 2016, 55, 8616-8626

Online Article:
http s:// pubs.acs.org/doi/abs/10.1021/acs.iecr.6b00547

Reprodu ce d (or 'Reproduced in part') with permiss ion from “ Hyd ro formylation
in Microemulsions: Proof of Concept in a Miniplant; Markus Illner, David
Müll er, Erik Esche, Tobi as Pogrzeba, Marcel Schmidt, Reinhard Schomäcker,
and Jens-Uwe Repke. Industrial & Engineering Chemistry Research, 2016, 55,
8616-8626.” Copyright (2016) American Chemical Society.

Hydroformylation in Microemulsions: Proof of Concept in a
Miniplant
Markus Illner, *
, † , ∥
David Mu ller, *
, ‡ , ∥
Erik Esche,
†
Tobias Pogrzeba,
§
Marcel Schmidt,
§
Reinhard Schoma cker,
§
Gu nter Wozny,
†
and Jens-Uwe Repke
†
†
Process Dynamics and Operations Group, Technische Universita t Berlin, Strasse des 17. Juni 135, Sekr. KWT-9, D-10623 Berlin,
Germany
§
Department of Chemistry, Technische Universita t Berlin, Strasse des 17. Juni 135, Sekr. TC8, D-10623 Berlin, Germany
‡
Evonik Technology & Infrastructure GmbH, Process Technology & Engineering, Paul-Baumann-Strasse 1, 45772 Marl, Germany
ABSTRACT: The implementation of the hydroformylation
reaction for the conversion of long-chain alkenes into
aldehydes still remains challenging on an industrial scale.
One possible approach to overcoming this challenge is to apply
tunable systems employing surfactants. Therefore, a novel
process concept for the hydroformylation of long-chain alkenes
to aldehydes in microemulsions is being investigated and
developed at Technische Universita t Berlin, Germany. To test
the applicability of this concept for the hydroformylation in
microemulsions on a larger scale, a miniplant has been
constructed and operated. This contribution presents the proof
of concept for hydroformylation in microemulsions carried out
during a 200 h miniplant operation. Throughout the operation
a stable aldehyde yield of 21% and a catalyst loss in the product
phase below 0.1 ppm were achieved, which con fi rms previous lab scale fi ndings. Additionally, solution strategies for a stable
continuous operation to overcome challenges such as foaming, phase separation issues, and coalescence dynamics are discussed
herein.
1. INTRODUCTION
One of the world ’ s most important applications of homoge-
neous catalysis on an industrial scale is the reaction known as
hydr ofo rmy lati on.
1 , 2
Toda y, pr odu cti on pl ants f or hy dro-
formylation products have reached a capacity of 11 million
tons per year.
3 − 5
The reaction, also known as oxo synthesis,
was originally discovered in 1938 by Otto Roelen.
6
In the
presence of an adequate transition metal, such as cobalt (Co)
or rhodium (Rh), unsaturated hydrocarbons (alkenes) react
with c arbon monoxid e and hy drog en to for m linea r or
branched aldehydes ( Figure 1 ). In general, n -aldehydes are
desired a s intermedi ates for sub sequent reac tions tow ard
alcohols, detergents, softening agents, fl avorings, and other
chemicals and are of great value by themselves.
A steady move from cobalt to rhodium-based catalysts has
taken place during the past few decades. The main reasons were
higher achievable activities and selectivities at overall milder
reaction conditions.
5
Additionally, improvements regarding the
normal:iso selectivity of the reaction have been obtained by
selecting and modifying the employed catalysts with stereo-
active ligands.
5 , 9
Obviously, these advancements have come at
the cost of more expensive catalyst complexes.
Therefore, increasing e ff ort has been made on developing
process concepts with a special focus on catalyst recovery. The
Ruhrchemie/Rho ne Poulenc (RCH/RP) process presents a
milestone in the process development of the hydroformylation
reaction.
3
A major advantage of this biphasic process is the
solubilization of the highly reactive ligand-modi fi ed rhodium-
based catalyst complex in an aqueous phase. In principle,
separation of the product can easily be achieved by simple
means of phase decantation. Catalyst leaching via the product
stream of the process, which is the standard disadvantage of
homogeneous catalysis, becomes negligible. Additionally, as
discussed by Haumann et al.,
10
the operating conditions of the
RCH/RP process are mild with pressures below 60 bar and
temperatures around 120 ° C. Given that negligible amounts of
Received: February 8, 2016
Revised: July 18, 2016
Accepted: July 21, 2016
Published: July 21, 2016
Figure 1. Reaction equation of the hydroformylation reaction. R is an
alkyl group.
7 , 8
Article
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Ind. Eng. Chem. Res. 2016, 55, 8616 − 8626
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catalyst are lost via the product phase, no side reactions are
observed in subsequent distillation steps. However, a major
drawback of the process lies in its limitation to short-chain
alkenes. Since alkenes longer than hexene have a limited
solubility in the aqueous phase, which results in a severe
decrease of reactivity, they are inadequate for the RCH/RP
process.
11
For longer-chain alkenes Bo rner et al.
5
report that
the conversion is carried out in single phase reactions at severe
process conditions (up to 300 bar and 200 ° C), using mainly
cobalt catalysts. Modifying the catalysts with phosphines, these
process conditions can be lowered signi fi cantly. Nevertheless,
these processes su ff er from lower selectivities toward the
desired aldehydes and thus a rather costly product separation.
Cons equ entl y, swi tchi ng the fee dst ock to war d long- cha in
alkenes remains challenging for the chemical industry to date.
To overcome this hurdle, a novel process concept is currently
under investigation within the Collaborative Research Center
InPROMPT/TRR 63 and presented in this contribution.
Therein, a surfactant is added to the system, to enhance the
miscibility between the long-chain alkene and an aqueous
catalyst solution leading to the formation of a microemulsion. A
highly hydrophilic ligand-modi fi ed rhodium catalyst is used to
achieve high selectivities at mild process conditions.
2
To carry out the hydroformylation reaction, the catalyst
needs to be activated. This is done by introducing synthesis gas
into the system. Carbon monoxide transforms the catalyst into
its active species.
12
With carbon monoxide and hydrogen as
reactants present, the formation of aldehydes starts immedi-
ately. After the reaction step, the mixture is led into a phase
separation unit, within which the thermomorphic behavior of
the micellar system can be exploited to separate and recycle the
catalyst from the oily product. The process concept can thus be
summarized as a mixer − settler concept shown in Figure 2 .
In order to investigate this novel concept at a larger scale, a
miniplant has been designed, constructed, and operated at
Tec hnisc he Univer sita t Berl in (TU Be rli n). The rein, the
hydroformylation of 1-dodecene as a model, biobased ole fi n
using a nonionic surfactant is carried out.
The aim of this contribution is to present the results from
long-term miniplant operation and to discuss the applicability
of such a process concept. Keeping an eye on economic
viability and sustainability, the presented results are analyzed
regarding speci fi c targets:
• long-term stable application of ligand-modi fi ed rhodium-
based catalysts for high reaction activity and normal:iso
selectivity
• realization of a homogeneous catalysis at mild reaction
conditions (low pressures and low temperatures)
• adequate separation of the catalyst complex from the
product phase after the reaction
Additionally, special attention is given to challenges which
have arisen during the implementation of this concept as well as
strategies to overcome these challenges.
2. BACKGROUND INFORMATION
The following sections discuss the state of the art of
microemulsions as reaction media and their capabilities for
catalyst recovery. Consequently, characteristics of oil − water −
surfactant systems and phenomena exploited to achieve the
desired process steps are highlighted.
2.1. State of the Art and Preliminary Investigations.
To date, various applications of surfactant containing reaction
systems have been reported. Among them, several organic
applications such as reduction, oxidatio n, and coupling
reactions at C  C bonds can be found.
14 , 15
For long-chain
alkenes of chain lengths up to C 16 , a feasible application of
ho moge neo usly c ata lyz ed hyd rof ormy lati on u sin g mice lla r
reaction media was presented by Van Vyve and Renken in
1999
16
for a lk enes . Al so, L i et a l.
17
reported increased
selectivities and higher reaction yields for the conversion of
1-dodecene in biphasic mixed micelle systems, depending on
the surfactant composition and micellar state. The direct
in fl uence of surfactants on the reaction performance was the
main focus of the studies of Haumann et al. in 2002.
10
They
reported the hydroformylation of 1-doecene in microemulsions
using wate r-soluble li gands. Compar ed to those, biphasic
water − oil systems showed no signi fi cant conversion of long-
chain alkenes to aldehydes. The addition of a surfactant,
however, enables the reaction. The main challenge lies in
determining an appropriate surfactant. The surfactant selection
is crucial for both the reaction performance and the subsequent
product separation.
18
The thermomorphic behavior of micellar
systems (see section 2.2 ) and therefore also the distribution of
the catalyst between all formed phases strongly depend on the
surfactant ’ s properties.
19
Furthermore, high reaction rates, clear
phase separation, and catalyst recovery also have to be realized
as continuous operations in a technical system to estimate
economic viability. Regarding the process concept in Figure 2 ,
no continuous operation on a miniplant or any comparable
scale was reported until now.
2.2. General Phase Separation Characteristics of Oil −
Water − Surf act an t Sys tem s. The addition of su ffi cient
amounts of surfactant to an oil and water mixture leads to
the formation of a microemulsion. From a macroscopic point of
view a microemulsion can be regarded as homogeneous. On a
microscopic scale it is heterogeneous with coexisting, nano-
meter-thin hydrophobic and hydrophilic layers.
20 , 21
For the
application here, a microemulsion can be used in two ways. It
acts as a tunable solvent, which on the one hand increases the
interfacial area during the reaction, and on the other hand
changes its phase separation behavior dependent on temper-
ature.
22
Thus, the reaction can be carried out in a homogeneous
mixture followed by a fast and pure phase separation in a
settler.
23
However, for this purpose the phase separation
characteristics of oil − water − surfactant systems must be well
understood.
24
The phase separation characteristics of a microemulsion
system formed with nonionic surfactants can be described by
Kahlweit ’ s fi sh diagram. The diagram is created by slicing
Gibbs ’ phase prism of an oil − water − surfactant system at an oil
Figure 2. Process concept for the hydroformylation of long-chain
alkenes in microemulsions.
13
Industrial & Engineering Chemistry Research Article
DOI: 10.1021/acs.iecr.6b00547
Ind. Eng. Chem. Res. 2016, 55, 8616 − 8626
8617

to water ratio of 1:1. Thus, the various phase states at di ff erent
temperatures and surfactant concentrations become visible.
Figure 3 shows a qualitative sketch of Gibbs ’ phase prism for an
arb itrar y oil − wa ter − su rfac tant s yste m and Ka hlw eit ’ s fi sh
therein.
A closer look at Kahlweit ’ s fi sh reveals several distinct phase
states. The fi sh ’ s body (micellar system) is established in case a
su ffi cient amount of surfactant is present (greater than the
critical micellar concentration, γ 0 ). A two-phase regime (2  )i s
created at low surfactant concentrations and low temperatures.
This is governed by a water and surfactant rich emulsions phase
at the bottom and an oily excess phase on top. As mentioned by
Mu ller et al., “ the surfactant is mainly dissolved in the water-
rich phase due to it s higher solubility the re at lower
temperatures. Hence, an oil-in-water (o/w) microemulsion is
formed. This regime can be desired for the product separation
step of a mixer − settler process as a pure product phase can be
removed while recycling the surfactant and water (aqueous
catalyst solution). ”
26
By increasing the temperature, a three-
phase region (3) is established in which the bulk of the
surfactant is located in a middle phase. In coexistence with this
middle phase an oil-rich top phase and a water-rich bottom
phase appear. Here, the catalyst is also mainly located in the
middle phase, whereas the oily excess phase still remains free of
catalyst.
19
Given its pure oil phase, this region is desirable for
the separation step. Two more regions are shown in Figure 3 .
The fi rst is the single-phase region on the right-hand side ( fi sh ’ s
fi n). Obviously this region may be suitable for the reaction, but
inadequate for separation purposes. The second undesired
region is the upper two-phase (2  ) region. There, the surfactant
lies dissolved in the top phase. This may be problematic,
because phase separation would lead to drastic surfactant and
water loss with the product phase. The surfactant as well as the
water (catalyst solution) trapped therein would have to be
replenished and separated in additional separation steps from
the product.
19
Regarding the phase separation dynamics, microemulsion
systems show a distinct reduction of the separation time in the
three-phase region (3) compared to the two-phase regions (2  ,
2  ). Depending on the applied surfactant, the required time for
achieving an equilibrium state increases by several orders of
magnitude on leaving this area.
19
Hence, for the construction of
a decanter with reasonable residence time, solely the three-
phase region is of interest. However, this causes two major
chal lenges t owar d proces s desig n and con trol. Firs t, the
concentration dependent location of Kahlweit ’ s fi sh needs to
be intensively investigated for the considered component
system in the miniplant. Second, the temperature only o ff ers a
small operational window regarding the temperature in the
decanter. Using this information on th e general phase
separation characteristics, the miniplant, and the settler in
particular, was constructed and operated. Here, an approach
described by Mu ller et al.
26
was applied, to systematically tackle
the unit design for such a multiphase system.
3. MATERIALS AND METHODS
At this point, the applied substances as well as the constructed
miniplant are introduced. A miniplant operation schedule is
presented to highlight applied operation strategies and discuss
their in fl uence on the system. Additionally, operational
challenges and solution approaches are discussed.
3.1. Materials. The applied substances can be categorized
into several groups: reactants, catalyst compounds, solubilizing
substances, and products.
The fi rst reactant is 1-dodecene (CAS Registry Number 112-
41-4, purchased from VWR), a C 12 alkene, which is used as an
exemplary unsaturated, long-chain hydrocarbon. The second
reactant is synthesis gas with a composition of 1:1 mol %
CO:H 2 with a purity of 5.0 purchased from Linde.
The applied catalyst consists of a rhodium-based precursor
[Rh(acac)(CO) 2 ] (CAS Registry Number 14874-82-9), spon-
sored by Umicore, and the water-soluble ligand SulfoXantPhos
(sulfonated form of XantPhos, CAS Registry Number 161265-
03-8), purchased from MOLISA GmbH. Both precursor and
ligand are dissolved in water.
The miscibility of 1-dodecene and the catalyst solution is
enabled by the nonionic surfactant Marlipal 24/70 (CAS
Registry Number 68439-50-9), sponsored by Sasol Germany
GmbH. Additionally, Na 2 SO 4 , purchased from Th. Geyer, is
added in small amounts as a separation enhancing additive.
Figure 3. Gibbs ’ phase prism of oil − water − surfactant mixtures at di ff erent temperatures (left) and Kahlweit ’ s fi sh (right). The fi gures are based on
and partially redrawn in accordance with the original images presented in ref 25 .
Industrial & Engineering Chemistry Research Article
DOI: 10.1021/acs.iecr.6b00547
Ind. Eng. Chem. Res. 2016, 55, 8616 − 8626
8618

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