微波辐射SnCl_4/C催化对羟基苯甲酸乙酯的合成与表征

Synthesis and Characterization of Ethyl p-Hydroxylbenzoate Catalyzed by SnCl_4/C under Microwave-Assisted Condition

在微波辐射条件下,以对羟基苯甲酸与乙醇为原料,SnCl4/C为异相催化剂,高效、绿色地合成对羟基苯甲酸乙酯.分别研究催化剂用量、醇酸摩尔比、反应时间、反应温度、微波辐射功率等对收率的影响,并采用傅里叶变换红外光谱(FT-IR)、核磁共振氢谱(1 H NMR)和质谱(MS)确定产物的结构.结果表明:合成对羟基苯甲酸乙酯最佳条件为n(对羟基苯甲酸)∶n(乙醇)=1∶4,反应时间为25min,催化剂的质量分数为10%,反应温度为120℃,微波辐射功率为640W,产品收率为95%;SnCl4/C催化剂循环使用4次后,仍然显示出良好的催化活性,产率可达89%.

Ethyl p-hydroxylbenzoate was produced from p-hydroxy benzoic acid and ethanol as starting materials by u- sing SnC14/C as efficient and green heterogeneous catalyst under microwaveassisted condition. The influences of the quantity of SnC14/C, the ratio of acid and ethanol, and reaction time and temperature factors on the esterification yield are discussed. The structure of ethyl p-hydroxylbenzoate was characterized by Fourier-transform infrared spectroscopy （FT- IR）, 1 H nuclear magnetic resonance spectroscopy （1 H NMR） and mass spectroscopy （MS）. The results showed that the optimal reactive conditions were as following： 10% catalyst, the ration of acid and ethanol I ： 4, the radiation time 25 minutes, the reaction temperature 120℃, the microwave power 640 W. Under the optimal reactive conditions, the yield of ethyl p-hydroxylbenzoate was up to 95 %. Moreover, SnC14/C catalyst can be recycled and reused at least 4 consecutive runs without a noticeable drop in the product yield （89%）.