A new non-phosgene route for synthesis of methyl N-phenyl carbamate from phenylurea and methanol

Methyl N-phenyl carbamate (MPC) was synthesized via a new non-phosgene route by reaction of phenylurea with methanol. The effects of catalysts, reaction temperature, reaction time and molar ratio of methanol to phenylurea were investigated. It was found that the catalyst played an important role in this reaction. Although MPC can be prepared in the absence of catalyst, 95.21% conversion of phenylurea and 84.75% selectivity of MPC were obtained in the presence of methanol-pretreated PbO catalyst under the reaction condition of 413 K for 4 h. In addition, XRD and IR were used to identify the structure of pretreated PbO catalyst. It was found that PbO was transformed into Pb(OCH3)(2) after the pretreatment with methanol at 413 K. An addition-elimination reaction mechanism for the formation of MPC via the reaction between phenyl urea and methanol was proposed, based on the product distribution. (C) 2003 Elsevier B.V. All rights reserved.