Pd(Ⅱ)/γ-Al_2O_3催化下有机锡试剂和α-卤代酸酯偶联反应

Pd(Ⅱ) Catalyst on γ-Al_2O_3 in Coupling Reaction of Organotin and Organtic Halides

用浸渍法制备了Pd(Ⅱ)/γ-Al2O3催化剂。制备了有机锡试剂三丁基苯基锡、三丁基苄基锡、三丁基烯丙基锡,详细考察了影响有机锡试剂和α-卤代酸酯偶联反应的各种因素,得出了反应的最佳条件:有机锡试剂与α-卤代酸的摩尔比为10.4:10,丙酮溶剂最佳用量15mL,反应时间20h,催化剂用量1.5g。结果表明,在有机锡试剂和α-卤代酸酯偶联反应中,钯实际用量很少,对有机锡的摩尔比为8.6×10-3:1。该催化剂有较高的选择性,很高的催化活性,酯基在反应中不被破坏。催化剂可以重复使用,催化剂循环使用5次,偶联反应的产率还很高。用XPS、XRD、电镜等方法对催化剂进行了表征,证明了催化活性中心是金属态的钯。

Pd(Ⅱ) catalyst on γ-Al 2O 3 was prepared by soak method, and Bu 3SnPh、Bu 3SnCH 2Ph、Bu 3SnCH 2CH=CH 2 were prepared too. The influence of catalyst amount, organotins/organic halides mole ratio, reaction time and solvent was studied and the optimum reaction conditions were determined. They are as follows: organotins/organic halides in mole ratio 10.4:10, acetone amount is 15 mL and reaction time is 20 h, catalyst amount is 1.5 g. The result shows that in the coupling reaction a few amout of Pb is consumed and the mole ration of it to organotin is 8.6×10 -3 :1. The catalyst has high catalytic activity and chemical selectivity in coupling reaction of organotins and organic halides. The ester is not destroyed. The catalyst can be reused and the yields is still higher after using of five times. The catalyst has been investigated by XPS, XRD and electron microscope. The experimental results show that the metallic Pd is the active center.