己内酰胺对甲基苯磺酸离子液体中甲苯的选择性硝化反应

Regioselective Nitration of Toluene in Caprolactam-p-toluenesulfonate Ionic Liquid

制备了一种低毒性的新型Brφnsted酸性离子液体己内酰胺对甲基苯磺酸([CP]PTSA)作为催化剂和溶剂,用于催化甲苯与等摩尔的体积分数为67%HNO3的硝化反应,用核磁共振、红外光谱对[CP]PTSA的结构进行了表征。考察了不同的反应温度、反应时间及催化剂用量等因素对甲苯硝化反应的产率和对位选择性的影响。得出最佳反应条件为:温度55℃,时间24h,离子液体用量占甲苯摩尔分数的20%,产物硝基甲苯中邻与对位异构体质量比为1.2,较硝-硫混酸硝化的相应比值(1.6)显著降低,硝基甲苯的产率达37.1%。离子液体重复使用4次仍表现出较好的催化活性及对位选择性。用质谱分析对回收的离子液体的结构进行了表征。结果表明,该离子液体的结构稳定。

A novel low toxicity eaprolaetam-eation-based Bronsted acid ionic liquid （IL） was prepared and used as the solvent and catalyst in the nitration of toluene with 1 equiv of 67% nitric acid. The structure of the ionic liquid was characterized by ^1 H NMR and FTIR. The effect of reaction temperature, reaction time and the amount of catalyst on product yield and para-selectivity for the nitration of toluene was investigated. Nitrotoluene with a yield of 37. 1% and an ortho-para isomer ratio of 1.2 was obtained under the optimal conditions. The ionic liquid was recycled 4 times with a slightly decreased yield and the same para-selectivity. The structure of the reused ionic liquid was characterized by MS, and it was found that the IL was stable under the reaction conditions