水溶剂体系液体酸催化合成二苯甲烷二氨基甲酸甲酯

Synthesis of methylene diphenyl dicarbamate in water-solvent system over mixed acid catalyst

以水作溶剂、液体酸为催化剂,对苯氨基甲酸甲酯(MPC)与甲醛缩合制备二苯甲烷二氨基甲酸甲酯(MDC)的反应进行了研究,考察了硫酸为单一液体酸催化剂以及硫酸、盐酸、羧酸等各种液体酸互相混合后形成混合酸的催化活性。实验发现,在水溶剂体系中,以n(H2SO4)∶n(有机弱酸)=2∶1的混合酸为催化剂的催化活性最佳,在反应温度95℃、反应时间3.5 h,n(MPC)∶n(HCHO)=2∶1的条件下,MPC转化率达95.1%,MDC收率达79.6%;将混合酸催化剂循环3次后,MDC的收率仍保持68.9%。

The synthesis of methylene diphenyl dicarbamate(MDC) from methyl phenyl carbamate(MPC) and formaldehyde with liquid acids as catalysts was studied in aqueous phase using water as reaction medium.The catalytic activity of sulphuric acid as well as mixed acids containing a series of mineral acids and organic acids were investigated.The mixed acid containing the sulphuric acid and organic acid was found to display better catalytic activity than others in aqueous solvent.It was found that the mixed acid had the highest catalytic activity when the molar ratio wasn(H2SO4)/n(organic acid)=2∶1.The conversion of MPC was 95.1% and the yield of MDC reached 79.6% under the optimum conditions thatn(H2SO4)/n(organic acid)=2∶1,n(MPC)/n(HCHO)=2∶1,reaction temperature of 95℃,reaction time of 3.5 h.The mixed acid still shown high catalytic activity even it was reused for 3 times,here the yield of MDC was 68.9%.