Chinese Journal of Chemical Engineering, Vol.13, No.6, 764-770, 2005
Enantioselective hydrogenation of ethyl 2-oxo-4-phenylbutyrate on cinchona-platinum catalysts
Enantioselective hydrogenation of ethyl 2-oxo-4-phenylbutyrate to ethyl (R)-2-hydroxy-4-phenyl- butyrate on Pt/gamma-Al2O3 modified by 10,11-dihydrocinchonidine was studied by investigating the influences of the amount of modifier, initial concentration of reactant, pressure and temperature on conversion and enantiometric excess in a stirred autoclave and the effects of the liquid velocity, gas velocity, modifier concentration and various catalytic beds in a trickle-bed reactor. The maximum optical yields were about 50% and 60% in the two types of reactors, respectively. It was assumed that the total hydrogenation rate included the reaction rates over the unmodified and modified active sites on platinum surface and a kinetic model, which fitted the experimental data well in autoclave, was obtained. A simplified plug-flow model was proposed to describe the bed average efficiency of trickle-bed reactor.
Keywords:enantioselective hydrogenation;ethyl (R)-2-hydroxy-4-phenylbutyrate;trickle-bed reactor;kinetics