离子液体[BzMim][BF4]催化甲苯与盐酸和聚甲醛的氯甲基化反应

Chloromethylation of Toluene with Hydrochloric Acid and Polyformaldehyde Catalyzed by Ionic Liquid [BzMim][BF4]

摘要:

以1-甲基咪唑和氯化苄为原料合成中间体氯化1-苄基-3-甲基咪唑（[BzMim]Cl），而后与氟硼酸钠交换阴离子合成了一种新的离子液体[BzMim][BF4]，并考察了该离子液体催化甲苯与盐酸和聚甲醛的氯甲基化反应的催化活性和选择性。实验结果表明，[BzMim][BF4]能够催化以浓盐酸为原料的氯甲基化反应，目标产物甲基苄基氯的产率与文献报道以离子液体C12mimBr催化干燥氯化氢为原料的相仿；对同为浓盐酸原料的氯甲基化反应，其单氯甲基化选择性远高于文献报道的以离子液体[emim]BF4为催化剂的35%；当[BzMim][BF4]与甲苯的摩尔比为0.3，多聚甲醛（PF）与甲苯的摩尔比为1.3，浓盐酸与甲苯的摩尔比为7.5，80 oC下反应8 h时，目标产物甲基苄基氯的产率达到88.5%，单氯甲基化选择性高于99%。

Abstract:

A new ionic liquid catalyst [BzMim][BF4] was synthesized through a two-step reaction. First, [BzMim]Cl was synthesized by 1-methylimidazole and benzyl chloride, and then exchanged with NaBF4 to prepare [BzMim][BF4]. Its catalytic performance and product selectivity were investigated in the Blanc chloromethylation reaction of toluene. And the experimental results indicated that [BzMim][BF4] could catalyze the chloromethylation reaction using hydrochloric acid as reactant. Compared with similar reactions catalyzed by other ionic liquid catalysts in literature, the yield of reaction catalyzed by [BzMim][BF4] was similar with that using dry HCl catalyzed by ionic liquid C12mimBr; and the selectivity of mono chloromethylation was obviously higher than the reported 35% in the case of hydrochloric acid catalyzed by ionic liquid [emim]BF4. And when the mole ratio of [BzMim][BF4] to toluene was 0.3, the mole ratio of PF to toluene was 1.3, the mole ratio of hydrochloric acid to toluene was 7.5, and when the reaction was carried out at 80 oC for 8 h, the yield of the target product methyl benzyl chloride was as high as 88.5%, and the selectivity of mono chloromethylation was more than 99%.