Pt-containing zeolites for enantioselective catalytic hydrogenation of ethylpyruvate – effects of zeolite structures, solvent and modifier concentration

Abstract

Platinum-containing zeolites of the types Y, ZSM-5, ZSM-35 and β demonstrate their suitability as catalysts for enantioselective hydrogenation of ethyl pyruvate to ethyl lactate. The catalyst on the basis of a ZSM-35 shows the best enantioselectivity with conversions of more than 99% and it permits high reaction rates. Enantiomeric excess is strongly influenced by the type of solvent selected. Best results in selectivity are attainable by using solvents with dielectric constants of less than 10. An increase in chiral modifier concentration leads to a decrease in reaction rate of the hydrogenation of ethyl pyruvate. In this case the enantiomeric excess remains almost constant.