Über die Autorin bzw. den Autor

Boy Cornils has worked at the former Hoechst AG in Germany, where he was the director of the reasearch. He is the editor of several bestselling titles.

Wolfgang A. Herrmann is president of the Technical University of Munich and has received several awards for his work in organometallic chemistry, like the Otto-Bayer Medal, the ACS Award in Organometallic Chemistry, the Werner-Heisenberg Medal of the Alexander von Humboldt foundation and many more. He has authored a plethora of publications and is the editor of numerous bestselling books.

Istvan Horvath is Professor at the Eötvös Universitiy in Budapest. He is the Editor-in-Chief of the "Encyclopedia of Catalysis" and has chaired many meetings and symposia in the areas of green chemistry and catalysis.

Walter Leitner holds the chair of Technical Chemistry and Petrochemistry at RWTH Aachen (successor to Prof. Keim). In November 2003 he became external scientific member of the Max-Planck-Institut für Kohlenforschung.

Stefan Mecking was research associate at the Freiburg Materials Research Center and Institute of Macromolecular Chemistry of Albert-Ludwigs-University Freiburg. Since March 2004 he is full professor at Konstanz University, Chair of Chemical Materials Science. He has received the BASF Catalysis Award and the Otto-Roelen-Medaille.

H. Olivier-Bourbigou is research associate at the Ecole du Petrole et du Moteurs and her research interest are ionic liquids and green chemistry.

Dieter Vogt is full professor in inorganic chemistry and catalysis. He received his Ph.D. from Aachen University of Technology in 1992 with prof. W. Keim as supervisor. He did his Habilitation at the Institute of Industrial Chemistry and Petrochemistry of the RWTH Aachen. End of 1998 he was appointed as full professor of Inorganic Chemistry and Coordination Chemistry at Eindhoven University of Technology. His main research interest are in the field of homogeneous catalysis, catalyst recycling and new materials for application in catalysis.

Von der hinteren Coverseite

This long-awaited two-volume handbook is the one-stop reference for everybody working in the field of multiphase catalysis. Covering academic and industrial applications, it will set the standard for future developments.
All editors are top scientists with an industrial or academic background and have put together an international team to present every facet of this fascinating methodology -- including aqueous-phase catalysis, ionic liquids, fluorous-phase chemistry, supercritical solvents, and catalysis with polymer-bound ligands -- in a compact and competent manner.

From the Contents:

Organic Chemistry in Water
Homogeneous Catalysis in the Aqueous Phase
Technical Solutions
Technical Applications of Supercritical Fluids
Organic-Organic Biphasic Catalysis on a Laboratory Scale
Enantioselective Catalysis in the Fluorous Phase
Catalysis in Nonaqueous Ionic Liquids
Commercial Applications and Aspects of Ionic Liquids
Catalysis using Supercritical Solvents
Soluble Polymer-Bound Catalysts
Polymer-Bound Metal Complexes as Catalysts for C-C and C-N Coupling

Aus dem Klappentext

This long-awaited two-volume handbook is the one-stop reference for everybody working in the field of multiphase catalysis. Covering academic and industrial applications, it will set the standard for future developments.
All editors are top scientists with an industrial or academic background and have put together an international team to present every facet of this fascinating methodology -- including aqueous-phase catalysis, ionic liquids, fluorous-phase chemistry, supercritical solvents, and catalysis with polymer-bound ligands -- in a compact and competent manner.

From the Contents:

Organic Chemistry in Water
Homogeneous Catalysis in the Aqueous Phase
Technical Solutions
Technical Applications of Supercritical Fluids
Organic-Organic Biphasic Catalysis on a Laboratory Scale
Enantioselective Catalysis in the Fluorous Phase
Catalysis in Nonaqueous Ionic Liquids
Commercial Applications and Aspects of Ionic Liquids
Catalysis using Supercritical Solvents
Soluble Polymer-Bound Catalysts
Polymer-Bound Metal Complexes as Catalysts for C-C and C-N Coupling

Auszug. © Genehmigter Nachdruck. Alle Rechte vorbehalten.

Multiphase Homogeneous Catalysis, 2 Volumes

John Wiley & Sons

Chapter One

Boy Cornils, Wolfgang A. Herrmann, Istvn T. Horvth, Walter Leitner, Stefan Mecking, Hlne Olivier-Bourbigou, and Dieter Vogt

"Sipping a cup of decaffeinated coffee the reader may wonder on the somewhat unusual classification of solvents as 'alternative': alternatives to what? And why would we need alternative media for doing chemistry or for any other purpose? These may be the first questions for those who are just starting to discover the existing new developments on using solvents other than volatile and often toxic organics for synthesis and especially for catalytic reactions. Yes, indeed, ...".

Yes, indeed, similarly to an opening cornucopia, the arsenal of methods and techniques in homogeneous catalysis has offered remarkable progress in recent years. Above all, these improvements concentrate on the modification and the handling of homogeneous catalysts in general and the removal and subsequent recycling of catalysts in particular. The progress to be dealt with in this book has been rendered essentially possible by the introduction of separate phases in the context of "homogeneous" catalysis: an apparent contradiction with far-reaching consequences. For the first time, this book reviews all the realistic possibilities described so far using multiphase operation of homogeneous catalysis: processes with organic/organic, organic/aqueous, or "fluorous" solvent pairs (solvent combinations), nonaqueous ionic solvents, supercritical fluids, and systems with soluble polymers. In Figure 1, the family tree of homogeneous catalysis proves that this recent research extends considerably the scope of the work.

Following the logic of this tree, the multiphase processes on the left-hand side belong among the operations with "immobilized catalysts" but on "liquid supports". The topics of this book are the processes with the liquid supports water, supercritical fluids, ionic liquids, organic liquids, soluble polymers, and fluorous liquids; among these, only two processes (Ruhrchemie/Rhne-Poulenc and Shell SHOP) are operative industrially so far. The more important "leaves" of the family tree are shaded in gray.

In Figure 2, demonstrating the genesis of homogeneous and heterogeneous catalysis, the topical processes are on the borderline between heterogeneous and homogeneous catalysis (and catalysts).

Why multiphase systems? This goes back to the 1980s and the enormous impetus which was given to the homogeneous catalysis community by the first realization of Ruhrchemie/Rhne-Poulenc's oxo process at the Oberhausen plant site. Astonishingly, it was this development (and not the earlier SHOP process of Shell) that sensitized the scene to the possibilities of multiphase action: only on the basis of the "aqueous" activities that so much widespread and multi-faceted research work, with effects on the newer areas mentioned has been accomplished successfully. There was earlier work and proposals to imitate the decisive advantage of heterogeneous catalysis: the immediate separation of catalyst and substrates/ products just after reaction which makes it possible to avoid additional separation steps post-reaction, such as distillations and other thermally stressing procedures. All proposals have the same target: to enable the homogeneous catalyst to be bound to a suitable "support", i.e., another phase, without losing its superior homogeneous catalytic activity and selectivity. Within the scope of this book the editors define "phases" not only thermodynamically (as uniform states of matter of one substance which are separated (and separable) from each other by unequivocal phase boundaries; for example, water-ice or normal-supercritical states) but also as different states of aggregation of different compounds, such as systems consisting of water-organic liquids. Thus this book deals with homogeneous catalysts on liquid supports. Additionally, the processes described imply two- or three-phase reactions (the latter is the case if gaseous reactants complete the reaction scheme, e.g., hydrogen in hydrogenations or syngas in hydroformylations).

The use of liquids in homogeneous catalysis thus means not only a liquid support and from there a basic intervention in the handling and the operation of the catalyst, but also a modern separation technique for efficient work-up in organic synthesis. Figure 3 illustrates the enormous importance of the biphasic technique for homogeneous catalysis: the catalyst solution is charged into the reactor together with the reactants A and B, which react to form the solvent-dissolved reaction products C and D. The products C and D have different polarities than the catalyst solution and are therefore simple to separate from the catalyst phase (which may be recycled in a suitable manner into the reactor) in the downstream phase separation unit.

This double meaning of the multiphasic approach is specially visible in the case of fluorous liquids, where organic chemists are at least as interested as the catalytic community in the use of these fluids.

The ability of different combinations of solvent pairs to enable biphasic operation can be estimated on the one hand according to the principle of "like dissolves like" ("similia similibis solvuntur", as the old alchymists used to say) in respect to the solvent for the catalyst and, on the other hand, with the help of diagrams as shown in Figure 4 and of fundamental investigations.

The fundamentals of miscibility (solvation power, [E.sup.N.sub.T]) of various solvents from nonpolar, aprotic tetramethylsilane (TMS; with [E.sup.N.sub.T] = 0 as defined) to polar water ([E.sup.N.sub.T] = 1) are given by the solvent polarity scale in Figure 5.

This graph gives a selection of 14 (out of approximately 360) of the usual solvents above the baseline and seven more exotic solvents (supercritical C[O.sub.2] and ionic liquids included) below. The 14 compounds, from left to the right with increasing solvent polarity, include apolar, aprotic (such as TMS, cyclohexene, or benzene), bipolar (such as acetone or DMF), and eventually bipolar, protic solvents (cyclohexanol, ethanol, phenol). Using the [E.sup.N.sub.T] values, numerous solvent-dependent processes may be correlated with each other. Other measures that can be used for the estimation of miscibility/solvent power are the cohesive pressures, solubility parameters, dispersive forces, Kamlet-Taft parameters, etc. Solvent combinations of exotic members and systems with more than two members are known and have been recommended, but their application has been concentrated in the lab because of economic disdavantages with their handling and recyclability/ separability.

A recent proposal concerns mixed organic-aqueous tunable solvents (OATS) such as dimethyl ether-water, the solubility of which for substrates can be influenced by a third component such as carbon dioxide. C[O.sub.2] acts as a "antisolvent" and as a switch to cause a phase separation and to decant the phases from each other (preferably under pressure). This behavior makes the operation of bi- or multiphase homogeneous catalytic processes easier and more economic: the preferential dissolution at modest pressure of carbon dioxide causes phase separation which results in large distribution coefficients of target molecules in biphasic organic-aqueous systems. This extraordinary behavior lead to a sophisticated...