Kinetic Studies on the Optical Resolution of 2-Alkanol by Pseudomonas cepaciaLipase Catalyzed Transesterification with Vinyl Acetate in Organic Solvent.

Abstract

The optical resolution data were analyzed for Pseudomonas cepacia lipase (PCL) catalyzed transesterification between vinyl acetate and 2-alkanol in organic solvent. The plots of log E (E: the enantiomeric ratio as the reaction is irreversible) agaist the extent of conversion (c) showed the maxima for all systems used. The competitive reaction in the optical resolution was verified by the analysis of the resolution data and an accordance of the enantiomeric excess (ee) vs. c plots between racemic and optically pure alcohols. The reverse reaction in the optical resolution was experimentally proved by a decrease in optical purity for the reaction of optically pure 1-methylheptyl acetate and 2-octanol in the presence of PCL. The first order plot showed a lenearity for the reaction with (R)-2-octanol but curveture for the (S) counterpart. Based on the above observations, we concluded that the transesterification with vinyl acetate did not obey the reported optical resolution equations because acetylation of the (S) isomer in racemic 2-alkanol with the acetyl-enzyme intermediate was surpressed. Thus, E increased with c in the range of below 0.5.