磷钨酸银催化合成柠檬酸三丁酯

Synthesis of Tributyl Citrate Catalyzed by Silver Salts of Phosphotungstic Acid

采用沉淀法制备了三种磷钨酸银盐(Ag_xH_(3-x)PW_(12)O_(40),x=1,2,3),并考察了它们对酯化合成柠檬酸三丁酯(TBC)的催化性能。FT-IR和XRD表征结果表明,三种磷钨酸银盐均较好的保持了Keggin结构。在三种磷钨酸银盐中,Ag_1H_2PW_(12)O_(40)的催化活性最高。以Ag_1H_2PW_(12)O_(40)为催化剂,考察了催化剂用量、酸醇比、反应温度和时间对合成TBC反应的影响。当正丁醇与柠檬酸的物质的量之比为4:1,Ag_1H_2PW_(12)O_(40)用量为柠檬酸质量的1.5%,温度150℃,反应时间为3h,酯化率可达到95.3%。此外,Ag_1H_2PW_(12)O_(40)易于分离,经过4次使用后,其催化活性没有发生显著变化。

Three silver salts of phosphotungstic acid（AgxH3（3-x）PW（12）O（40）, x = 1,2, 3） were prepared by the method of precipitation, and used as catalysts for the synthesis of tributyl citrate（TBC） by esterification.According to the results of characterization by means of FT-IR and XRD,the Keggin structure was maintained on three AgxH（3-x）PW（12）O（40） catalysts. Among them, Ag1 H2 PW（12）O（40） performed the highest catalytic activity.Effects of catalyst dosage, molar ratio of citric acid to n-butanol, temperature and reaction time on the synthesis of TBC were also investigated.The optimal molar ratio of citric acid to n-butanol was 10 ： 1,and the esterification rate could reach to 95. 3% using 1. 5% Ag1 H2 PW（12）O（40）（based on the mass of citric acid） as catalyst at 150℃ within3 h.In addition, the separation of Ag1 H2 PW（12）O（40） from reaction mixture was simple, and the catalytic activity of Ag1 H2 PW（12）O（40） had no viewable change after 4 runs.