Abstract:

Screening of catalyst for clean synthesis of methyl N-phenyl carbamate (MPC) through coupling route was performed under pressure, and process optimization, recycling of catalyst, and characterization of catalyst were also studied.The results showed that Bu₂SnO was the best one among the screened catalysts.Under the conditions that the molar ratio of dimethyl carbonate (DMC) to N,N′-diphenyl urea (DPU) was 10∶1, the amount of catalyst Bu2SnO was 2%, reaction temperature was 160℃, and reaction time was 2 h, the yield of MPC reached 98%, which was more than 77%, the reported yield of MPC with catalyst Bu₂SnO in the literature.Catalytic performance of Bu₂SnO was constant after four cycles.Catalyst Bu₂SnO before reaction and after reaction was characterized with FTIR, XPS and XRD.The analysis of XRD and XPS showed that the catalyst separated by the precipitator water from reaction solvent was still Bu₂SnO, but FTIR showed presence of new compounds.Since trace components or amorphous compounds in samples can not be detected by XPS or XRD, it could be concluded that most of the catalyst separated by the precipitator water from reaction solvent was Bu₂SnO with a small amount of possibly catalytic intermediates.