【摘要】 以硅钨酸为催化剂、二乙二醇二甲醚为溶剂,对苯氨基甲酸甲酯(M PC)与甲醛缩合反应制备二苯甲烷二氨基甲酸甲酯(MDC)进行了研究。考察了M PC与甲醛摩尔比、反应温度、反应时间和硅钨酸用量对M PC转化率和MDC收率的影响,得到最佳的反应条件:M PC与甲醛的摩尔比为8∶1,反应温度100℃,反应时间4.5h,硅钨酸与M PC的摩尔比为2.1∶100。在此优化条件下反应,MDC的收率为62.8%。对硅钨酸催化M PC与甲醛缩合反应的历程进行了讨论,硅钨酸既有催化反应物种形成活性中间体的活性质子,又有对活性中间体具有稳定化作用的硅钨酸阴离子,从而具有很高的催化活性。更多还原

【Abstract】 Methylene diphenyl dicarbamate(MDC),an important chemical intermediate for polyurethane,was synthesized from N-phenyl carbamate(MPC)and formaldehyde on silicotungstic acid catalyst with diethylene glycol dimethyl ether as solvent.Effects of mole ratio of MPC to formaldehyde,reaction temperature,reaction time and catalyst dosage on condensation reaction were studied.Optimal reaction conditions were:mole ratio of MPC to formaldehyde 8 ∶1,mole ratio of silicotungstic acid to MPC 2.1 ∶100,reaction time 4.5h and reaction temperature 100℃.Under above conditions,yield of MPC could reach 62.8%.Mechanism of the condensation reaction on silicotungstic acid catalyst was suggested according to experimental results.Silicotungstic acid possessed either H~+ as active intermediate formed in reaction,or silicotungstic acid group anion which could stabilize the active intermediate.Therefore activity of the catalyst was quite high.更多还原