Catalysis overview

D Souza98] D Souza, D. 1998. Interfaces, collaborations, refinements, and frameworks in Catalysis. Software Development, March Journal of 00 Programming, May. See also http //www.iconcomp.com/papers/catalysis-overview/catalysis-overview.pdf. 

Catalysis of reductive processes is extensively practiced, but since the catalysts are often organometallic, the discussion of this topic is diferred to the companion article (Organometallic Catalysis (Overview)). 

This chapter concludes our discussion of applications of surface chemistry with the possible exception of some of the materials on heterogeneous catalysis in Chapter XVIII. The subjects touched on here are a continuation of Chapter IV on surface films on liquid substrates. There has been an explosion of research in this subject area, and, again, we are limited to providing just an overview of the more fundamental topics. 

Finally, Chapter 6 will provide an overview and some important conclusions will be drawn concerning the use of aqueous media in oiganic chemistry with a special emphasis on catalysis. 

A micelle-bound substrate will experience a reaction environment different from bulk water, leading to a kinetic medium effect. Hence, micelles are able to catalyse or inhibit organic reactions. Research on micellar catalysis has focused on the kinetics of the organic reactions involved. An overview of the multitude of transformations that have been studied in micellar media is beyond the scope of this chapter. Instead, the reader is referred to an extensive set of review articles and monographs" ... 

In summary, the work in this thesis provides an overview of what can be achieved with Lewis-acid and micellar catalysis for Diels-Alder reactions in water as exemplified by the reaction of3-phenyl-l-(2-pyridyl)-2-propene-l-ones with cyclopentadiene. Extension of the observed beneficial effect of water on rates and particularly enantioselectivities to other systems is envisaged. 

Very recently, Olivier-Bourbigou and Magna [15], Sheldon [16], and Gordon [17] have published three excellent reviews presenting a comprehensive overview of current work in transition metal catalysis involving ionic liquids, with slightly different emphases. All three update previously published reviews on the same topic, by Wasserscheid and Keim [18], Welton [19] and Seddon and Holbrey [20]. 

Abstract After an overview of chiral urea and thiourea synthetic methods, this review describes the main applications of urea and thiourea complexes in asymmetric catalysis. Some recent examples of thioureas as catalysts are also presented. Coordination chemistry of ureas and thioureas is briefly discussed. 

In addition, there are the highly appreciated review journals, which publish overviews of the status of certain topics of interest in the field. Advances in Catalysis, Catalysis Reviews Science Engineering and Catalysis, Specialist Periodical Reports publish the most exhaustive reviews. CaTTech is a colorful magazine that publishes shorter reviews along with news from the catalysis community. Also the News Brief section of Applied Catalysis fulfills this important role. 

The development of ammonia synthesis represents a landmark in chemical engineering, as it was the start of large-scale, continuous high-pressure operation in flow reactors, and in catalysis, because the numerous tests of Mittasch provided a systematic overview of the catalytic activity of many substances. 

Surface science studies have generated much insight into how hydrocarbons react on the surfaces of platinum single crystals. We refer to Somorjai [G.A. Somor-jai. Introduction to Surface Chemistry and Catalysis (1994), Wiley, New York] for a detailed overview. Also, the reactions of hydrocarbons on acidic sites of alumina or on zeolites have been studied in great detail [H. van Bekkum, E.M. Flanigan and J.C. Jansen (Eds.), Introduction to Zeolite Science and Practice (1991), Elsevier, Amsterdam],... 

The reader is referred the recent book by Bell and Pines [2] for a more complete overview of the various methods and objectives in NMR studies of solid acids and other heterogeneous catalysis. In the present contribution we illustrate the application of H, and MAS NMR to two archetypal solid acids, Brpnsted sites in zeolites and solid metal halides such as aluminum chloride and bromide powders which exhibit "Lewis superacidity". An important characteristic of the more recent work is the integration of quantum chemical calculations into the design and interpretation of the NMR experiments. 

Support materials are commonly u.sed in heterogeneous catalysis. Their major function is to maximize the dispersion of the active phase by providing a large surface area over which the active phase can be distributed. In this way the cataly.st material is shaped into a form suitable for use in technical reactors. Supports are not always chemically inert they can also show certain catalytic activity and often they act as a stabilizer for the actual active phase. A number of materials are u.sed as catalyst supports. Table 3.2 gives an overview. 

Huber, G. W. Dumesic, J. A., An overview of aqueous-phase catalytic processes for production of hydrogen and alkanes in a biorefinery. Catalysis Today 2006, 111, 119. 

Various other biphasic solutions to the separation problem are considered in other chapters of this book, but an especially attractive alternative was introduced by Horvath and co-workers in 1994.[1] He coined the term catalysis in the fluorous biphase and the process uses the temperature dependent miscibility of fluorinated solvents (organic solvents in which most or all of the hydrogen atoms have been replaced by fluorine atoms) with normal organic solvents, to provide a possible answer to the biphasic hydroformylation of long-chain alkenes. At temperatures close to the operating temperature of many catalytic reactions (60-120°C), the fluorous and organic solvents mix, but at temperatures near ambient they phase separate cleanly. Since that time, many other reactions have been demonstrated under fluorous biphasic conditions and these form the basis of this chapter. The subject has been comprehensively reviewed, [2-6] so this chapter gives an overview and finishes with some process considerations. 

Why are transition metals so well suited for catalysis A complete treatment of this critical question lies well beyond the scope of this book, but we can focus on selected aspects of bond activation and reactivity for dihydrogen and alkene bonds as important special cases. Before discussing specific examples that involve formal metal acidity or hypovalency, it is convenient to sketch a more general localized donor-acceptor overview of catalytic interactions in transition-metal complexes involving dihydrogen49 (this section) and alkenes (Section 4.7.4). 

A large number of (mostly zero-valent) nickel-alkene complexes has been reported. Although these complexes have not been recently reviewed, their general properties and structures were expertly described in 1982 [21]. A complete overview of the reported nickel-alkene and nickel-alkyl complexes is beyond the scope of this section, in which a selection of nickel-alkene and nickel-alkyl complexes is described, mostly related to possible intermediates in hydrogenation catalysis. 

Asymmetric catalysis is a vital and rapidly growing branch of modern organic chemistry. Within this context, Ti- and Zr-based chiral catalysts have played a pivotal role in the emergence of a myriad of efficient and enantioselective protocols for asymmetric synthesis. In this chapter, a critical overview of enantioselective reactions promoted by chiral Zr-based catalysts is provided. Since an account of this type is most valuable when it provides a context for advances made in a particular area of research, when appropriate, a brief discussion of related catalytic asymmetric reactions promoted by non-Zr-based catalysts is presented as well. 

For a general overview of recent advances in this area, see Comprehensive Asymmetric Catalysis (Eds. E. N., Jacobsen, A. Pfaltz, H. Yamamoto), Springer, Berlin, 1999. 

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