Effects of impregnation solvents on asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutyrate on Pt/alumina-carbon catalysts

Alumina-Carbon composites, synthesized by chelate-assistant co-assembly method, were impregnated by solution of H2PtCl6 dissolved in water, ethanol and their mixture to prepare Pt/Alumina-Carbon catalysts. Our current study by using X-ray diffraction (XRD), N2 sorption and transmission electron microscopy (TEM) revealed that ethanol solution of H2PtCl6 was favorable for the high Pt dispersion, while the catalyst prepared from the mixed solution of H2PtCl6 obtained the largest Pt particles. The results of asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutyrate showed that the Pt particle size of the catalyst prepared from the aqueous solution of H2PtCl6 was in favor of high enantioselectivity. And this cinchonidine-modified catalyst afforded the highest enantiomeric excess in acetic acid. Moreover, the catalyst showed excellent reusability, which could be reused for 22 times without distinct loss in activity and enantioselectivity.