水杨酸乙酯的硫酸催化合成工艺优化

Optimization of Ethyl Salicylate Synthesis Catalyzed by Sulfuric Acid

目的优化硫酸催化合成水杨酸乙酯的生产工艺。方法以水杨酸和乙醇为反应底物,硫酸为催化剂,在反应体系中匀速加入高浓度的乙醇,边蒸馏边回收乙醇和水的混合物。用水和碳酸钠(Na_(2)CO_(3))溶液清洗反应产物后,通过减压蒸馏精制得到高纯度的水杨酸乙酯。结果当起始投料质量比为水杨酸∶乙醇∶硫酸=50∶15∶1,乙醇浓度为95%,反应温度为110℃,乙醇回流比为55%~65%时,酯化收率大于90%,所得水杨酸乙酯的纯度高于99%,为最佳反应条件。结论该工艺催化活性高、选择性好,合成产物杂质少,符合药用级水杨酸乙酯的工业化生产。

OBJECTIVE To optimize the synthesis of ethyl salicylate catalyzed by sulfuric acid.METHODS Salicylic acid and ethanol were used as reactive substrates,with sulfuric acid as catalyst to synthesis ethyl salicylate.Dropwise added ethanol with high concentration in constant speed to the reactive system and recycled the mixture of ethanol and water during distillation.After the reaction products were washed with water and Na2CO3solution,ethyl salicylate was purified through vacuum distillation.RESULTS When the initial material weight ratio of salicylic acid,ethanol and sulfuric acid was 50∶15∶1,concentration of ethanol was 95%,reactive temperature was 110℃,reflux ratio of ethanol was 55%-65%,which was the optimal condition,the yield ratio and purity of ethyl salicylate was above 90%and 99%,respectively.CONCLUSION With the advantages including high catalytic activity,good selectivity,less impurities,the synthesis process could be applied to manufacture pharmaceutical grade ethyl salicylate.