Asymmetric Reduction of Acetophenone to α-Phenylethanol by Candida valida under Compressed CO2

The asymmetric reduction of acetophenone to optically active α-phenylethanol catalyzed by cells of Candida valida CICC1444 under compressed CO2 without agitation was investigated. The reaction by the unimmobilized whole cells under compressed CO2 was feasible, and the R-enantiomer of α-phenylethanol was excessive. The yield of α-phenylethanol was greatly influenced by operating parameters such as concentration of acetophenone, cell mass, temperature, and pressure. Compared with the reaction at ambient pressure without agitation, the conversion of acetophenone and yield of α-phenylethanol under compressed CO2 were increased by 20% and 40%, respectively, and the enantiomeric excess of (R)-α-phenylethanol was increased by 5%–10%.