Catalytic action of comicelles containing imidazolyl and hydroxyl groups in the hydrolysis of enantiomeric esters |
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Authors: | Yasuji Ihara Yoshiharu Kimura Mamoru Nango Nobuhiko Kuroki |
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Institution: | Yamaguchi Women''s University, 3-2-1 Sakurabatake, Yamaguchi 753, Japan;Department of Applied Chemistry, University of Osaka Prefecture, Sakai, Osaka 591, Japan |
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Abstract: | The rate constants for hydrolysis of the enantiomers of amino acid p-nitrophenyl esters catalyzed by bifunctional comicellar catalysts containing the imidazolyl and hydroxyl groups have been determined at pH 7.30, 0.02 m phosphate buffer, and 25°C. The kinetic analysis suggests a reaction scheme which involves acylation followed by deacylation at the imidazolyl group. Although no appreciable cooperative catalytic efficiencies are observed between the bifunctional groups in the acylation step, it is found that the deacylation rates are thus accelerated by surfactant hydroxyl groups, and some of the stereoselective acyl transfer reaction occurs from the imidazolyl to the hydroxyl group in optically active comicellar systems. |
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Keywords: | To whom correspondence should be addressed |
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