稀土金属在离子液体中催化甲苯的硝化反应

Rare-earth Metals Catalyzed Nitration of Toluene in Ionic Liquid

将稀土金属盐负载在己内酰胺类离子液体上组成稀土金属盐和离子液体的复合物作为催化剂和溶剂,用于催化甲苯与等摩尔67%HNO3的硝化反应,利用核磁共振对离子液体的结构进行了表征。考察了不同的反应温度、反应时间及催化剂的种类和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:反应温度55℃,反应时间24h,苯磺酸镱[Yb(BSO)3]和苯磺酸己内酰胺离子液体(CPBSO)用量分别占甲苯的摩尔分数为5%和10%。产物硝基甲苯中邻、对位异构体质量比o/p=1.1,较硝硫混酸硝化(o/p=1.6)显著降低,产率达46.5%。离子液体重复使用4次均表现出较好的催化活性及对位选择性。

Composites of rare-earth metal complexes supported on caprolactam-cation-based Bronsted acid ionic liquids（IL） were prepared, and used as solvents and catalysts in the nitration of toluene by equiv mole of 67% nitric acid. The structure of the ionic liquid was characterized by ^1H NMR. The effects of reaction temperature, reaction time and the type and amount of catalyst on product yield and para-selectivity for the nitration of toluene were investigated. Nitrotoluene with a yield of 46.5% and an ortho-para isomer ratio of 1.1 was obtained under the optimal conditions. In addition, the mixture of IL and rare-earth complexes could be removed easily and recycled 4 times with the same ortho-para selectivity and only a small decrease in the yield, suggesting a possibility of a more economic and green process.