Heterogeneous Catalytic Hydrogenation of Chiral Amino Acid Methyl Esters to Amino Alcohols with Retention of Configuration Over Mg-Modified Cu/ZnO/Al2O3 Catalyst

Abstract

Selective hydrogenation of amino acid methyl esters to chiral amino alcohols is an important and fascinating process. The CuZn0.3Mg0.1AlOx catalyst for the synthesis of chiral amino alcohols was prepared by the fractional co-precipitation method in the 50–100 g scale. The effect of the reduction gas on the catalytic activity, and the effects of the reaction conditions (R-p-m/Cat, temperature, reaction time, H2 pressure and solvent) on the catalytic hydrogenation of R-phenylglycine methyl ester (marked as R-p-m) were investigated. When R-p-m in the ethanol solvent was hydrogenated at 5 MPa of H2 and 80 °C for 10 h over this catalyst reduced by H2, 87.7% yield of R-phenylglycinol with ~ 100% ee value was obtained, and its reaction activation energy (Ea) was 36.7 kJ/mol. After repeated usage 16 times, its catalytic activity was hardly varied. Using this catalyst to catalyze the preparation of other amino alcohols, the high yield of product with ~100% ee value was obtained also.