Kinetic model of resolution of 4-methoxymandelic acid enantiomers by lipase-catalyzed transesterification reaction

Abstract

This paper reports the kinetics resolution of (R,S)-4-methoxymandelic acid (4-MMA) by lipase AK-catalyzed transesterification reaction, using vinyl acetate (VA) as acyl donor in methyl tert-butyl ether (MTBE). Considering the Ping-Pong bi-bi mechanism with 4-methoxymandelic acid inhibition, the kinetic model was established. Kinetic parameters were obtained by fitting time-concentration curves for different initial 4-methoxymandelic acid concentrations. The average relative error below 3.0% indicated that the model predictions were in good agreement with the experimental data. Furthermore, the kinetic model was employed to predict the effects of enzyme loading, initial vinyl acetate concentration and reaction time on enantiomeric excess (ees) and conversion of substrate (c), and to optimize the conditions. The excellent results with high conversion of 4-MMA (50.2%) and large enantiomeric excess of substrate (98.6%) were achieved under the optimal conditions.