Enzymatic kinetic resolution of secondary alcohols by esterification with FA under vacuum |
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Authors: | Roxana?Irimescu Takao?Saito Email author" target="_blank">Katsuya?KatoEmail author |
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Affiliation: | (1) Bio-functional Ceramics Group, Ceramics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, 463-8560 Nagaoya, Japan |
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Abstract: | Kinetic resolution of some chiral secondary alcohols 2-octanol, 1-phenylethanol, and 1-(2-naphthyl)ethanol] with high enantioselectivity
(E>300) was achieved by direct esterification with FFA catalyzed by immobilized Candida antarctica B lipase. The reaction equilibrium was shifted toward the synthetic side by the removal of the water formed under vacuum.
Esterification of rac-2-octanol at an alcohol/FFA molar ratio of 2∶1 was used as a model reaction. The chain length of FFA and their structure
influenced the reaction rate but did not have a measureable effect on E. The best acyl donor was decanoic acid: >47% conversion at 4 h with virtually perfect E. Temperature did not affect E in the range studied (15–45°C), but temperatures at the higher end afforded improved reaction rates. The reaction rates and
E were compared for three different acyl donors. The initial reaction rate increased in the following order: ethyl laurate
< lauric acid < vinyl acetate. E was high (E>300) for all acyl donors. Racemic 1-phenylethanol and 1-(2-naphthyl)ethanol were also resolved by direct esterification with
decanoic acid in short times (3 and 4 h, respectively) with E>300 and excellent conversions. Preparative-scale kinetic resolution of 2-octanol was also performed. |
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Keywords: | Enantioselectivity enzymatic kinetic resolution free fatty acid lipase secondary alcohol vacuum |
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