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Transfer hydrogenation is the addition of hydrogen (H2; dihydrogen in inorganic and organometallic chemistry) to a molecule from a source other than gaseous H2. It is applied in industry and in organic synthesis, in part because of the inconvenience and expense of using gaseous H2. One large scale application of transfer hydrogenation is coal liquefaction using "donor solvents" such as tetralin.〔Speight, J. G. "The Chemistry and Technology of Coal" Marcel Dekker; New York, 1983; p. 226 ff. ISBN 0-8247-1915-8.〕 ==Organometallic catalysts== In the area of organic synthesis, a useful family of hydrogen-transfer catalysts have been developed based on ruthenium and rhodium complexes, often with diamine and phosphine ligands.〔T. Ikariya, K. Murata, R. Noyori "Bifunctional Transition Metal-Based Molecular Catalysts for Asymmetric Syntheses" Org. Biomol. Chem., 2006, volume 4, 393-406.〕 A representative catalyst precursor is derived from (cymene)ruthenium dichloride dimer and the tosylated diphenylethylenediamine. These catalysts are mainly employed for the reduction of ketones and imines to alcohols and amines, respectively. The hydrogen-donor (transfer agent) is typically isopropanol, which converts to acetone upon donation of hydrogen. Transfer hydrogenations can proceed with high enantioselectivities when the starting material is prochiral: :RR'C=O + Me2CHOH → RR'C *H-OH + Me2C=O where RR'C *H-OH is a chiral product. A typical catalyst is (cymene)''R,R''-HNCHPhCHPhNTs, where Ts = SO2C6H4Me and ''R,R'' refers to the absolute configuration of the two chiral carbon centers. This work was recognized with the 2001 Nobel Prize in Chemistry to Ryōji Noyori.〔Shimizu, H., Nagasaki, I., Matsumura, K., Sayo, N., and Saito, T. "Developments in Asymmetric Hydrogenation from an Industrial Perspective" Acc. Chem. Res. 2007, vol. 40, pp. 1385-1393. 〕 Another family of hydrogen-transfer agents are those based on aluminium alkoxides, such as aluminium isopropoxide in the MPV reduction; however their activities are relatively low by comparison with the transition metal-based systems. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「transfer hydrogenation」の詳細全文を読む スポンサード リンク
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