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Platinum Metals Industrial Catalysts Catalysis of Organic Reactions EDITED by M Platinum Metals Industrial Catalysts Catalysis of Organic Reactions EDITED BY M. G. SCAROS AND M. L. PRUNIER, Marcel Dekker, New York, 1995, 599 pages, ISBN 0-8247-9364-1, U.S. $195.00 This book comprises a set of papers presented reactant purity, agitation and poisons are at the 15th Conference on Catalysis of Organic considered. This is followed by a paper detail- Reactions, held in Phoenix, Arizona, in May ing noble metal recovery operations and the var- 1994. It covers a variety of topics, such as het- ious steps involved in the noble metal “loop”. erogeneous catalysis, asymmetric hydrogena- Heterogeneous catalysis in organic synthesis tion, hydrogenation, oxidation, hydroformyla- is discussed by R. L. Augustine and colleagues tion, catalyst design and catalyst characterisation. from Seton Hall University, New Jersey. This One topic which is emphasised is hydrogena- is illustrated by the platinum catalysed oxida- tion (alpha to omega), and this is intended to tion of alcohols, carbon-carbon bond forming allow a better understanding of the entire reactions of supported palladium catalysts for process, from choosing a catalyst to the noble the Heck type arylation of allylic groups, and metal “loop”. There are over 60 papers and 186 by enantioselective heterogeneous catalysis, contributors, with a healthy number of these which includes the hydrogenation of a-ketoesters being from industry. A large proportion of the to chiral a-hydroxyesters using chinchona alka- papers deal with reactions involving platinum loid modified platinum catalysts. group metal catalysts, reflecting their impor- A detailed study of the homogeneously pal- tance to both academia and industry. ladium catalysed coupling of aryl halides and The initial paper, by R. J. McNair from aryl triflates to itaconate diesters is discussed by Johnson Matthey, provides an overview of the M. G. Scaros and co-workers from G. D. Searle process of catalyst selection for heterogeneous and Monsanto. This can provide a convenient platinum group metal catalysts in a new hydro- route to the intermediate E-benzylidene succi- genation process. It includes discussion on the nate diesters, which in turn can be hydrogenated reasons behind the choices of catalytic metal, to chiral R-benzylsuccinates with a high degree catalyst support, reactor design, catalyst design, of optical purity, using rhodium-dipamp com- catalyst separation, and spent catalyst recov- plexes as catalysts. In the coupling reactions aryl ery and refining. There is a description of the iodides were more effective than aryl bromides, influence of catalyst preparation methodology and the nature of the itaconate diester did not on the selectivity of supported metal catalysts, appear to affect the efficiency of the reaction: exemplified by the hydrogenation of phenyl- aryl triflates were more sensitive to the reaction acetylene using 5 per cent palladium on carbon. conditions than the aryl halides were. Other topics that are dealt with include the effect The DuPont process for the direct combina- of the preparative method on metal dispersion, tion of hydrogen and oxygen to form hydro- distribution and level of reduction and how each gen peroxide is described in a contribution by can affect the catalyst performance and, in par- J. R. Kosak from E. I. DuPont de Nemours. ticular, its selectivity. Some of the problems that are associated with The effect of reaction conditions on catalyst the traditional anthraquinone process, such as selectivity is then discussed by F. P. Daly and consecutive hydrogenation and oxidation steps, colleagues from Degussa, with reference to the and also aqueous-organic extractions have been hydrogenation of oximes and unsaturated C 18 overcome. It has been shown that doping a sup- acids using supported platinum group metal ported palladium powder with platinum has a catalysts. Several factors, such as temperature, synergistic effect, and this has resulted in an pressure, catalyst loading level, solvent system, improved yield and selectivity to hydrogen Platinum Metals Rev., 1995, 39, (2), 65-67 65 peroxide. The attachment of this catalyst to a Academy of Sciences, and R. A. Sheldon and stainless steel mesh using washcoating techniques co-workers from Delft University of Technology has avoided some of the drawbacks of a slurry and the Technical University of Budapest, cataly.t system and has provided an efficient means respectively, revisit the topic of heterogeneous for directly combining hydrogen and oxygen. asymmetric hydrogenation catalysts. In the paper The synthesis of primary amines from olefins, by Sheldon the influence of alkaloid-type chi- syngas and ammonia is dealt with by J. F. ral auxiliaries on the hydrogenation of carbonyl Knifton from Texaco Chemical Company and and olefinic groups by supported palladium and by J. J. Lin from Shell Development Company. platinum catalysts is described, and shows that This oxoamination reaction has been extended the highest enantioselectivities, comparable with to butenes and homogeneous cobalt, ruthenium the previously reported chinchonidine, were and rhodium systems have all proved effective, obtained with the vinca-type alkaloid with ruthenium being the most productive. vinpocetinm. The theme of the application of catalysis to Asymmetric Catalysis the life sciences is continued by D. Forster and Several chapters then deal with the topic of co-workers !?om Monsanto and Searle Discovery asymmetric synthesis. There has been partic- Research, who have used homogeneous cataly- ular interest in this as chiral molecules have sis including hydroformylation with rhodium, become indispensable in the life sciences where reductive amination with ruthenium, and there is a drive towards more active, specific hydrosilylation with rhodium-phosphines, for drugs which do not have the undesired side reactions on template polymers which can result effects that are associated with the presence of in the synthesis of tailored polymeric drug unwanted isomers. Ruthenium-BINAP com- delivery systems. plexes have become a popular catalyst system Some catalytic problems relating to rapid deac- to study, since they have been shown to be effec- tivation and scale up during the reductive ami- tive with a range of substrates. S. Akutagawa nation of aldehydes and ketones, using palla- from Takasago International Corporation, dis- dium or platinum on carbon catalysts, are cusses this area, with reference to the hydro- described by J. J. Birtill from ICI. This is genation of aliphatic ketones, a-substituted P- followed by a paper from R. E. Malz and ketoesters, and also the practical application colleagues of Uniroyal Chemical Company and of this technology towards the synthesis of Georgetown Medical School, on the reductive Vitamin E, p-lactam intermediates and bio- alkylation of acetophenone with aniline. They degradable polymers. show that bisulphided catalysts are more effec- Further chapters deal with the use of ruthe- tive than their unsulphided counterparts and nium-BINAP systems for the hydrogenation of that a 3 per cent PtS, on carbon catalyst is supe- unsaturated carboxylic acids and with multi- rior to sulphided rhodium, ruthenium, nickel nuclear NMR observations on the nature of the or palladium systems for that reaction. catalyst in the reduction of ketoesters. The influence of the medium on the nickel The homogeneous hydrogenation of imines is catalysed hydrogenation of 2-methyl glutaro- discussed by B. R. James from the University of nitrile is described by G. Cordier from RhBne- British Columbia, who describes work on asym- Poulenc. In this reaction subsequent dehydro- memc imine hydrogenation with rhodium phos- genation of the intermediate by a catalyst of phine catalysts, and by P. A. Chaloner and col- palladidsilica in a fixed bed configuration gave leagues from the University of Sussex who the desired product, P-picoline, in high yield. A describe the reduction of PhN=CHPh using paper by D. G. Blackmond and A. Waghray from iridium phosphine complexes. the University of Pittsburgh, demonstrates the J. L. Margitfalvi, from the Central Research role that alkali promoters can play in hydro- Institute for Chemistry of the Hungarian genation. During the hydrogenation of 3-methyl Platinum Metals REV.,1995, 39, (2) 66 2-butenal, catalysed by ruthenium/silica, the selective transformations of polyols are described addition of potassium results in a shift in selec- by P. Gallezot and colleagues from the Institut tivity towards the unsaturated alcohol, provided de Recherches sur la Catalyse-CNRS. In par- that the potassium is in close proximity to the ticular they discuss the oxidation of glyoxal to ruthenium. glyoxylic acids using platinum on carbon, and Further examples of the influence of promot- the conversion of glucose to gluconic acid using ers in hydrogenations are given in other papers. a palladium on carbon catalyst impregnated with These include rhodium-tin on silica catalysts, bismuth. The latter catalyst system possesses which give high selectivities to crotyl alcohol some advantages over the commercial enzymatic in the hydrogenation of crotonaldehyde; the process in that the reaction is carried out in one selective hydrogenation of carboxylic acids to step in a single vessel with high yield per alcohols by sol-gel ruthenium-tin catalysts; the catalyst weight. hydrogenation of bisphenol A using lithium Papers by G. G. Stanley from Louisiana State hydroxide as a modifier, and the influence of University, on the uses of homobimetallic co- alloying
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