Combinatorial chemistry, catalyst development

The major impetus for the development of solid phase synthesis centers around applications in combinatorial chemistry. The notion that new drug leads and catalysts can be discovered in a high tiuoughput fashion has been demonstrated many times over as is evidenced from the number of publications that have arisen (see references at the end of this chapter). A number of )proaches to combinatorial chemistry exist. These include the split-mix method, serial techniques and parallel methods to generate libraries of compounds. The advances in combinatorial chemistry are also accompani by sophisticated methods in deconvolution and identification of compounds from libraries. In a number of cases, innovative hardware and software has been developed tor these purposes. 

In this brief review we illustrated on selected examples how combinatorial computational chemistry based on first principles quantum theory has made tremendous impact on the development of a variety of new materials including catalysts, semiconductors, ceramics, polymers, functional materials, etc. Since the advent of modem computing resources, first principles calculations were employed to clarify the properties of homogeneous catalysts, bulk solids and surfaces, molecular, cluster or periodic models of active sites. Via dynamic mutual interplay between theory and advanced applications both areas profit and develop towards industrial innovations. Thus combinatorial chemistry and modem technology are inevitably intercoimected in the new era opened by entering 21 century and new millennium. 

This chapter will cover the efforts that have been made to use the principles of combinatorial chemistry in the development of new catalysts. In the last few years there has been a lively discussion of what is the correct definition of combinatorial chemistry. Some workers reserve the term combinatorial chemistry for the synthesis and evaluation of mixtures. For the purpose of this chapter, we will employ a liberal interpretation of the term. Since one of the definitions of the word combinatorial is, of or involving combinations (14), we will use the term to include what may be referred to as parallel synthesis. In parallel synthesis, one generates a combination of molecules, be they in separate vials or on separate pins. One view may be that a collection of vessels represents a combination of molecules. It is for this... 

In this chapter, the recent advances in amidocarbonylations, cyclohydrocarbonylations, aminocarbonylations, cascade carbonylative cyclizations, carbonylative ring-expansion reactions, thiocarbonylations, and related reactions are reviewed and the scope and mechanisms of these reactions are discussed. It is clear that these carbonylation reactions play important roles in synthetic organic chemistry as well as organometallic chemistry. Some of the reactions have already been used in industrial processes and many others have high potential to become commercial processes in the future. The use of microwave irradiation and substitutes of carbon monoxide has made carbonylation processes suitable for combinatorial chemistry and laboratory syntheses without using carbon monoxide gas. The use of non-conventional reaction media such as SCCO2 and ionic liquids makes product separation and catalyst recovery/reuse easier. Thus, these processes can be operated in an environmentally friendly manner. Judging from the innovative developments in various carbonylations in the last decade, it is easy to anticipate that newer and creative advances will be made in the next decade in carbonylation reactions and processes. 

With the remarkable outcomes that were introduced above, a large number of industrial chemical companies now view combinatorial chemistry as important to the future of catalyst development, though it is very expensive to sustain substantial investment both in capital and in resources in order to establish an advanced combinatorial capability. 

Combinatorial chemistry is an important method for the development of pharmaceuticals [51], agrochemicals [52], catalysts [53] and materials [54]. It can be performed either on a solid phase or in solution, both processes having advantages and disadvantages. A procedure that combines the advantages of both is based on... 

Maier WF, Combinatorial Chemistry—Challenge and chance for the development of new catalysts and materials, Angew. Chem. Int. Ed., 38 9, 1999. 

Soluble polymers have attracted recent attention in catalysis and combinatorial chemistry.1 3 When used in catalysis by organometallic compounds, soluble polymer ligands offer the following advantages The reaction is homogeneous in nature and separation of catalysts can be easily achieved by filtration or precipitation. We have now developed a new class of polymer ligands based on fluoroacrylate-arylphosphine copolymers for catalysis in periluorocarbon solvents and supercritical C02 (scC02). 

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