Application of a Burkholderia cepacia lipase-immobilized silica monolith micro-bioreactor to continuous-flow kinetic resolution for transesterification of ( R, S)-1-phenylethanol

Abstract

Burkholderia cepacia lipase was immobilized in silicates forming from n-butyl-substituted precursors within a silica monolith from methyl-substituted precursors. The resultant preparation gave about 12 times higher rates of transesterification of ( R, S)-1-phenylethanol with vinyl acetate and an approximately two-fold increase in the enantioselectivity toward ( R)-1-phenylethanol, as compared to a non-immobilized counterpart. The highest enzymatic activity and enantioselectivity (reaching 250) were found at a low water activity of 0.11. The continuous-flow kinetic resolution of ( R, S)-1-phenylethanol was successfully conducted using lipase-immobilized silica monolith micro-bioreactors with various inside diameters ranging from 0.25 to 1.6 mm. The reactor performance during continuous operation was consistent with the prediction from the batch reactor. A steady state conversion of 40% and enantiomeric excess more than 98% were maintained over a time period of 15 days.