超声辅助稀土改性二氧化锡催化合成乙酰水杨酸

以水杨酸、乙酸酐为原料,稀土钇（Y³⁺）、铈（Ce³⁺）、镧（La³⁺）改性氧化锡（SnO₂）为催化剂,在超声辅助下合成乙酰水杨酸,Y³⁺/SnO₂催化剂表现出最佳的催化效果。通过单因素实验考察了水杨酸与乙酸酐物质的量比、催化剂用量、反应时间、超声功率、反应温度、析晶时间对合成乙酰水杨酸反应的影响。通过红外光谱（FT-IR）、扫描电镜（SEM）和X射线衍射（XRD）等手段对催化剂和合成的产物进行了表征。最佳实验条件：水杨酸与乙酸酐物质的量比为1∶2、催化剂（Y³⁺/SnO₂）用量为水杨酸质量的8%、反应时间为30 min、反应温度为70 ℃、超声功率为70 W、析晶时间为2 h。在此条件下,乙酰水杨酸的产率为83.6%。催化剂重复使用5次后仍有较高的催化活性。该催化剂具有催化效果好、无污染、无腐蚀性、重复利用率高等优点。

Catalytic synthesis of acetosalicylic acid over ultrasound-assisted rare earth modified SnO2

Acetylsalicylic acid was synthesized with salicylic acid and acetic anhydride as raw materials,rare earth(Y³⁺,Ce³⁺,La³⁺)modified SnO2 as catalyst assisted by ultrasound irradiation and the Y³⁺/SnO₂ catalyst showed the best catalytic performance.The effects of amount-of-substance ratio of salicylic acid to acetic anhydride,amount of catalyst,reaction time,ultrasonic power,reaction temperature and crystallization time on the synthesis of acetylsalicylic acid were investigated.The catalysts and synthetic products were characterized by FT-IR,SEM and XRD.The optimum experimental condition with the yield of acetylsalicylic acid of 83.6%was obtained as follows:the amount of substance ratio of salicylic acid to acetic anhydride is 1∶2,the amount of catalyst(Y³⁺/SnO2)is 8%that of salicylic acid,reaction temperature is 70℃,ultrasonic power is70 W,reaction time is 30 min and crystallization time is 2 h.The catalyst can be reused for 5 times which still remains high catalytic activity.The catalyst has the advantages of good catalytic effect,no pollution,no corrosion and high reuse rate.