Catalytic Synthesis of Methylene Diphenyl Dicarbamate in AcOH/H2O Mixed Solvent

In a mixed solvent of acetic acid(AcOH)/water, methylene diphenyl dicarbamate(MDC) was synthesized by the condensation of methyl phenyl carbamate(MPC) and formaldehyde in the presence of an inorganic acid catalyst. Based on the different solubilities to MPC and MDC, the mixed solvent showed higher catalytic performance than pure water. The mixed solvent not only promoted the condensation of MPC but aslo exhibited the advantage of the product separation with the reactants. Under the optimized conditions: a H2SO4 mass fraction of 31%, a reaction temperature of 95 degrees C and reaction time of 3.5 h, the yield of MDC reached 74.3%. In addition, the recycle of the solvent was also investigated.