负载型PVP-Pt催化剂催化2-氧-4-苯基丁酸乙酯的不对称加氢

Asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutyrate with PVP-Ptsupported catalysts

分别采用乙醇、甲醛、甲酸钠、硼氢化钠为还原剂,聚乙烯吡咯烷酮(PVP)为稳定剂,制备了负载型PVP-Pt/γ-Al2O3催化剂,考察了催化剂对2-氧-4-苯基丁酸乙酯不对称加氢合成(R)-2-羟基-4-苯基丁酸乙酯的性能,其中硼氢化钠作为还原剂时性能最佳。研究了制备条件如还原温度、还原浓度、还原介质、PVP/Pt物质的量比以及反应溶剂、时间等因素对催化结果的影响。实验结果表明,在PVP/Pt=5∶1、还原温度0℃、NaBH4浓度为0.5 mol/L、乙醇作为还原介质制备的催化剂,对2-氧-4-苯基丁酸乙酯(EOPB)不对称加氢的转化率可达100%,对映选择性为76.8%e.e.。

A series of catalysts PVP-Pt/γ-Al2O3 were prepared by different reduction methods （ethanol,HCHO,HCOONa,and NaBH4） in the presence of PVP （polyvinylpyrrolidone） as stabilizer,the catalytic performance for asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutyrate to ethyl （R）-2-hydroxy-4-phenylbutyrate was tested.The catalyst prepared by using NaBH4 as reducing agent showed the best overall performance.The effect of various catalyst preparation conditions,such as reduction temperature,NaBH4 concentration,the medium in which reduction was carried out, PVP/Pt mole ratio and reaction solvent and time,was also investigated. Ethyl （R）-2-hydroxy-4-phenylbutyrate could be obtained with 100% yield and 76.8% e.e. when catalyst was prepared at 0 ℃ using 0.5 mol/L NaBH4 in a medium of ethanol.