微波辐射下磺酸基功能化离子液体无溶剂催化合成4-甲基香豆素及其衍生物

研究了3种磺酸基功能化离子液体催化香豆素及其衍生物的合成,取代酚与乙酰乙酸乙酯在无溶剂微波辐射条件下,通过Pechmann缩合反应,合成了一系列4-甲基香豆素衍生物,探讨了反应时间、反应温度、催化剂用量、离子液体重复使用性能诸因素对产品产率的影响。结果表明,离子液体C3SO3Hmim]HSO4是合成目标产物的良好催化剂,微波辐射时间10 min,反应温度100℃,n(酚)∶n(乙酰乙酸乙酯)=1∶1,催化剂用量x(C3SO3Hmim]HSO4)=20%时,最高产率可达94%。该法反应条件温和,操作简便,产物易分离,产率高,环境友好,离子液体可重复使用4次。

Synthesis of Coumarin Derivatives with Microwave Irradiation Solvent-Free Catalyzed by SO3H Functionalized Ionic Liquid

The coumarin derivatives of phenols and ethyl acetoacetate were synthesized via Pechmann condensation using SO3H functionalized ionic liquid as catalyst.The optimum reaction conditions were as follows:n(phenols)∶ n(ethyl acetoacetate)=1∶ 1,microwave irradiation reaction time 10 minute and reaction temperature 100 ℃.The highest yield can reach 94% in the presence of x(C3SO3Hmim]HSO4)=20% as catalyst and under solvent-free conditions.This method has the advantages of mild reaction conditions,easy operation,high yields and being environmentally benign.Moreover,the catalyst could be reused for at least four times.