Catalytic Synthesis Of Benzene, Methyl Carbamate

Methyl N-phenyl carbamate (MPC) is an important organic intermediate, it mainly used in the preparation of pesticide, medicine and isocyanate and other chemicals. In this dissertation, a process of MPC catalytic synthesis from dimethyl carbonate and diphenyl urea with various catalysts was investigated under low pressure condition, and the optimal catalyst was established. The various reaction conditions on the synthesis of methyl N-phynel carbamate were studied as well as the reaction mechanism. Moreover, The experiments of producing MPC hundred-ton per year under low-pressure condition were investigated. The main research contents and results are as follows:(1) The effects of various catalysts on the synthesis of MPC under low pressure condition were investigated. It was found that HOPbOCH₃ played higher performance than others.(2) The factors such as reaction pressure, reaction time, reaction temperature, raw material ratio, the dosage of catalyst and catalyst reusage influenting on synthesis of MPC were investigated under low-pressure condition. It was found that the yield of MPC reached 98.9% under the optimal condition that n (DMC): n (DPU) is 5: 1, temperature is 160°C, reaction time is 120 min, reaction pressure is 0.5 Mpa ,the dosage of catalyst is 1 wt %.(3) Catalysts before reaction and after reaction were characterized with FT-IR, SEM, XRD, and the results showed that catalyst after reaction may be changed into Pb₃ (CO₃)₂.(OH)₂, 2PbCO₃.Pb(OH)₂ or the mixture. Based on the results of this analysis, the reaction mechanism was discussed.(4) The experiments of producing MPC hundred-ton per year under low-pressure condition were investigated. It was found that the yeild of MPC can reach 99.0%, and some techenial specification Has been obtained.