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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([Bz Mim]Cl),而后与氟硼酸钠交换阴离子合成了一种新的离子液体[Bz Mim][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。结果表明,[Bz Mim][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C12mim Br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[Bz Mim][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℃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%。
The intermediate 1-benzyl-3-methylimidazolium chloride ([Bz Mim] Cl) was synthesized from 1-methylimidazole and benzyl chloride and then a new ionic liquid was synthesized by anion exchange with sodium fluoborate [Bz Mim] [BF4], and investigated the catalytic activity and selectivity of the ionic liquid for the chloromethylation of toluene with hydrochloric acid and polyoxymethylene. The results showed that [Bz Mim] [BF4] could catalyze the chloromethylation reaction with concentrated hydrochloric acid. The yield of methylbenzyl chloride was similar to that reported in the literature using the catalytic hydrogenation of C12mim Br as raw material. For the chloromethylation reaction of concentrated hydrochloric acid, the selectivity to monochloromethylation is much higher than 35% of that reported in the literature [emim] BF4 as a catalyst. When [Bz Mim] [BF4] and toluene , The mole ratio of paraformaldehyde (PF) to toluene was 1.3, the molar ratio of concentrated hydrochloric acid to toluene was 7.5, the reaction time was 8 h at 80 ℃, the yield of methylbenzyl chloride was 88.5 %, Monochloromethylation selectivity higher than 99%.