Hydrolysis and Esterification with Lipase from Candida Cylindracea. Influence of the Reaction Conditions and Acid Moiety on the Enantiomeric Excess |
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Authors: | Erland Holmberg Peter Szmulik Torbj
Rn Norin Karl Hult |
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Affiliation: | a Department of Biochemistry and Biotechnology, The Royal Institute of Technology, Stockholm, Swedenb Department of Organic Chemistry, The Royal Institute of Technology, Stockholm, Sweden |
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Abstract: | The enantiomeric ratio for hydrolysis and synthesis of 1-phenyl ethanol esters of straight chain aliphatic carboxylic acids catalyzed by Candida cylindracea lipase was determined. A distinct maximum in enantiomeric ratio was observed for valeric and caproic acid in the hydrolytic direction. No significant maximum could be determined in the esterification reaction. Even though the enzyme provided larger enantiomeric ratios in the synthetic direction the enantiomeric excess of the alcohol was not higher. The enantiomeric excess was depressed by racemization reactions in the esterification as the reaction approached thermodynamic equilibrium at an insufficient conversion. While choosing the optimal chain length of the acyl donor is important in hydrolytic reactions it seems to be of greater value to raise the equilibrium conversion in the esterification reactions. |
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Keywords: | Lipase Candida cylindracea hydrolysis esterification enantiomeric excess enantiomeric ratio equilibrium conversion carboxylic acid chain length |
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