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合成了具有不同ZnCl2摩尔分数的BrФnsted-Lewis双酸性离子液体[HO3S-(CH2)4-mim]Cl-xZnCl2,采用Hammett指示剂与紫外联用法测定了其酸强度,考察了其在苯氨基甲酸甲酯(MPC)与甲醛(HCHO)缩合制备二苯甲烷二氨基甲酸甲酯(MDC)反应中的催化性能,并考察了反应条件对MDC收率和MPC转化率的影响。结果表明,当x=0.7时该离子液体的催化活性最高。以[HO3S-(CH2)4-mim]Cl-0.7ZnCl2为催化剂兼溶剂,在反应温度70℃、反应时间60min、MPC与HCHO的摩尔比为10、离子液体与MPC的质量比为2的条件下,MDC收率最高可达99.1%。用水处理反应液并通过减压蒸馏回收的离子液体可以循环使用5次,其催化活性基本不变。
The BrФnsted-Lewis double acidic ionic liquids [HO3S- (CH2) 4-mim] Cl-xZnCl2 with different ZnCl2 mole fractions were synthesized and their acid intensities were determined by Hammett indicator and ultraviolet spectrophotometry. The catalytic performance of methyl methacrylate (MPC) and formaldehyde (HCHO) condensation in the preparation of methyl diphenyl methane dicarbamate (MDC) was investigated. The effects of reaction conditions on the yield of MDC and the conversion of MPC were also investigated. The results show that the ionic liquid has the highest catalytic activity when x = 0.7. The molar ratio of MPC to HCHO was 10 at a reaction temperature of 70 ℃ and a reaction time of 60 min with [HO3S- (CH2) 4-mim] Cl-0.7ZnCl2 as catalyst and solvent. The mass ratio of ionic liquid to MPC was 2 Under the MDC yield up to 99.1%. The ionic liquid recovered from the reaction solution by water and distilled under reduced pressure can be recycled 5 times without any change in its catalytic activity.