Resolution of racemic1-(4-methoxyphenyl) ethanol using immobilized lipase with high substrate tolerance

Abstract

The resolution of (R,S)-1-(4-methoxyphenyl) ethanol ((R,S)-MOPE) using an immobilized enzyme PM1000-TiO2-lipase in organic solvents was investigated. Under optimal conditions, the application of isopropyl as the organic solvent resulted in a reaction temperature of 40 °C, a ratio of (R,S)-MOPE to vinyl acetate of 2:1, the a water content of 0.56, a (R,S)-MOPE concentration of 200 mM, a (R,S)-MOPE conversion of 49.1 % and an enantiomer excess (ee) of (R)-ethyl acyl-MOPE of 99.1 %. These results indicate the high tolerance of immobilized lipase to the substrate with excellent enantioselectivity. The initial reaction rate increased with (R,S)-MOPE and vinyl acetate concentrations, thus a ping-pong Bi-Bi mechanism without inhibition model was selected for the (R,S)-MOPE resolution using PM1000-TiO2-lipase in the isopropyl ether. The fitting results of the kinetic parameters were as follows: a Michaelis constant for vinyl acetate KmA of 343.64 mM, a Michaelis constant for (R,S)-MOPE KmB of 104.81 mM, and a maximum reaction rate rmax of 0.49 mM min−1 mg−1. Moreover, the PM1000-TiO2-lipase demonstrated a high operational stability and maintained a relative activity of 86.0 % following 10 batch reactions.