负载型硫酸催化合成二苯甲烷二氨基甲酸甲酯

制备了SiO2负载硫酸催化剂,并将其用于催化苯氨基甲酸甲酯(MPC)与甲醛进行缩合反应合成二苯甲烷二氨基甲酸甲酯(4,4′-MDC)。以碳酸二甲酯(DMC)为溶剂,考察了反应时间、反应温度、原料配比、催化剂用量、溶剂用量等因素对该缩合反应的影响。得到的适宜反应条件为:催化剂的酸量与甲醛的摩尔比为1.3、MPC与甲醛的摩尔比为4、DMC与MPC的质量比为8、反应温度80℃、反应时间3h。在此条件下,4,4′-MDC的收率为56.0%,选择性为75.0%。在催化剂循环使用过程中,催化剂初次使用后,活性有所降低,但选择性提高;此后其催化活性和选择性稳定,循环使用4次基本保持不变。

Synthesis of 4,4'-Methylene Diphenyl Dimethylcarbamate Catalyzed by Silica-Supported Sulfuric Acid

Silica-supported sulfuric acid was prepared and used as catalyst in synthesis of 4,4'-methylene diphenyl dimethylcarbamate(4,4'-MDC) from methyl N-phenyl carbamate(MPC) and formaldehyde with dimethyl carbonate(DMC) as solvent. The influences of reaction time,reaction temperature,mole ratio of MPC to formaldehyde,dosage of silica-supported sulfuric acid catalyst and amount of solvent on 4,4'-MDC synthesis were studied. Under optimal reaction conditions:80 ℃,mole ratio of MPC to formaldehyde 4,mole ratio of H+ of catalyst to formaldehyde 1.3,mass ratio of DMC to MPC 8 and reaction time 3 h,yield and selectivity to 4,4'-MDC are 56.0% and 75.0%,respectively. The preparation of silica-supported sulfuric acid catalyst is simple. The H+ amount on catalyst is determined by titration. Although after first run catalytic activity of silica-supported sulfuric acid catalyst decreases and selectivity increases,there is no significant loss in both catalytic activity and selectivity in the following four cycles of runs.