硅胶固载[HSO_3-Pmim]HSO_4催化合成对羟基苯甲酸乙酯

Synthesis of ethyl p-hydroxybenzoate with ionic liquid [HSO_3-Pmim]HSO_4 immobilized on silica gel as catalyst

采用硅胶固载离子液体[HSO3-Pmim]HSO4催化对羟基苯甲酸和无水乙醇合成对羟基苯甲酸乙酯,考察了反应温度、反应时间、醇酸摩尔比和固载化离子液体用量对产率的影响。结果表明:硅胶固载离子液体[HSO3-Pmim]HSO4对对羟基苯甲酸乙酯的合成有较好的催化作用,在反应完毕后趁热过滤即可与对羟基苯甲酸乙酯分离;当醇酸摩尔比为3.5∶1,催化剂用量相对于酸的物质的量为4%,反应温度为95℃,回流反应3 h时,对羟基苯甲酸乙酯产率可达到92%以上;催化剂重复使用5次,其催化活性下降不明显。

Ethyl p- hydroxybenzoate was synthesized with ionic liquid [ HSO3 -Pmim] HSO4 immobilized on silica gel as catalyst. Effects of reaction temperature, reaction time, molar ratio of alcohol to acid and dosage of immobilized ionic liquid on the product yield were investigated. Results indicated that ionic liquid [ HSO3 - Pmim ] HSO4 immobilized on silica gel displays good catalytic action on the reaction for synthesis of ethyl p - hydroxybenzoate. After completion of the reaction, the catalyst can be easily separated from the reaction mixture by filtration during hot state. Under conditions as：molar ratio of alcohol to acid 3.5： 1, dosage of catalyst with respect to the acid 4% , reaction temperature 95 ℃ and reaction time with reflux 3 h, the yield can achieve higher than 92%. The catalyst can be reused for 5 cycles without significant loss of activity.