Stereoselective reduction of 2-phenylpropionaldehyde by alcohol dehydrogenase with cofactor regeneration

Abstract

Stereoselective reduction of 2-phenylpropionaldehyde catalyzed by alcohol dehydrogenase was investigated. Because of the water insolubility of the substrate and the target product (2-phenyl-1-propanol) organic solvent was used. The process was intensified by the cofactor (NADH) regeneration in the same media, using ethanol/acetaldehyde reaction as hydrogen carrier system. The aim of the study was to realize the enzymatic process and in situ cofactor regeneration, simultaneously. Laboratory experiments in shake flasks system were carried out to determine the optimal reaction conditions. Gas chromatography was used to follow the conversion and the enantioselectivity of this reaction. Different organic solvents were tested and isopropyl ether was found the most suitable. In water - isopropyl ether solvent system (ψr(VW/VO) = 37/63), optically pure (min. 95 %) (S)-2-phenyl-1-propanol was produced with 25 % yield after 2 h of reaction time.