作　　者： ; ; ; ; ; ; ; ;

机构地区： 华东理工大学化学与分子工程学院工业催化研究所

出　　处： 《分子催化》 2004年第6期456-461,共6页

摘　　要： 将天然手性高分子聚合物壳聚糖(CS)负载到SiO2上制得CS-SiO2载体,通过配位反应将Pd链接到该载体上,制得多相Pd-CS-SiO2手性加氢催化剂.以苯乙酮不对称氢转移加氢为模型反应,在空气氛围中研究了Pd-CS-SiO2的催化反应性能,考察了Pd的负载量、碱助剂、反应温度、反应时间等对反应转化率、选择性和对映选择性等的影响.结果表明,Pd-CS-SiO2催化剂具有较好的催化活性和选择性.使用强碱NaOH为助催化剂时,可提高氢转移加氢反应的速率和转化率;高的Pd负载量有利于苯乙酮转化率的提高,降低Pd的负载量有利于提高产物的对映选择性;提高反应温度有利于提高催化剂的反应活性,降低反应温度有利于提高产物的对映选择性.在30℃反应24h,产物R-1-苯乙醇的对映体过量值可达13.7%. The natural biopolymer of chitosan was supported on the surface of silicon dioxide, and then palladium was coordinated on it, to prepare the palladium-chitosan-silica complex (Pd-CS-SiO_2)chiral heterogeneous catalyst. The asymmetric transfer hydrogenation of acetophenone to R(S)-1-phenyl ethanol in atmosphere with 2-propanol as H-donor and solvent was studied as a model reaction. The effects of the Pd loading, reaction temperature, reaction time, and promoter of base on the performance of the catalyst were investigated. The results indicate that the Pd-CS-SiO_2 catalyst has a good catalytic activity and selectivity to the product for the asymmetric hydrogen transfer reduction of acetophenone. The addition of NaOH can increase the reaction rate and conversion of acetophenone significantly. The conversion of acetophenone increases with an increase of the Pd loading, but the enantiomeric excesses of 1-phenyl ethanol is higher at lower Pd loading. After reaction at 80 ℃ for 24 h, the conversion of acetophenone is 100% with 98% selectivity to 1-phenyl ethanol. At 30 ℃, the enantiomeric excess of R-1-phenyl ethanol reaches to 13.7%.

关 键 词： 苯乙酮 苯乙醇 氢转移 多相手性加氢 壳聚糖 对映选择性

领　　域： [理学] [理学]