Asymmetric hydrogen transfer reactions promoted by homogeneous transition metal catalysts

Article Abstract:

The catalytic asymmetric reduction of multiple bonds by hydrogen transfer, known as transfer hydrogenation, is described. The hydrogen donor, which is rarely a dihydrogen, may be an olefin, a primary or secondary alcohol or formic acid and its salts. The hydrogen acceptors are usually ketones, alpha,beta-olefinic carbonyls, acids and esters, imines and nitro compounds. The discovery of active homogeneous catalysts and more efficient H-donors has given impetus to wider use of the process, the various types of which are discussed.

Chirality

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Catalysis by heteropoly acids and multicomponent polyoxmetalates in liquid-phase reactions

Article Abstract:

Heteropoly acids (HPAs) are found to be good acid and oxidation catalysts for liquid-phase organic reactions in homogeneous and heterogeneous systems as they have strong Bronsted acidity, which greatly exceeds that of ordinary mineral acids and solid acid catalysts. Furthermore, HPAs' abilities to stabilize organic intermediates, be in its pseudoliquid phase and to have no side reaction effects, have contributed to heighten its catalytic activity and reaction selectivity.

Acids

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Heterogeneous catalysis

Article Abstract:

Heteropoly compounds have been found to be good acid and oxidation catalysts because of their molecularity, unique reaction field, catalysts design at both atomic and molecular levels and the unique basicity of their polyanions. These compounds are already being applied to a number of industrial processes. One of which is the direct oxidation of ethylene to acetic acid, which is catalyzed by palladium plus heteropoly acids.

Analysis, Heterogeneous catalysis

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