Synthesis of Diphenyl Carbonate from Carbon Dioxide, Phenol, and Carbon Tetrachloride Catalysed by ZnCl2 Using Trifluoromethanesulfonic Acid as Functional Co-Catalyst

Abstract

Diphenyl carbonate (DPC) was synthesised from carbon dioxide, phenol, and carbon tetrachloride catalysed by the Lewis acid ZnCl2 with the addition of co-catalyst. It was found that common bases are not effective co-catalysts for the production of DPC, and only slight enhancement in the catalytic activity of ZnCl2 was observed in the presence of inorganic additives such as inorganic carbonates and quaternary ammonium salts. Although poor conversion of phenol and yield of DPC were obtained using ZnCl2 or trifluoromethanesulfonic acid (CF3SO3H) as the sole catalyst, the catalytic activity of ZnCl2 was significantly improved by the addition of a catalytic amount of CF3SO3H. CF3SO3H has been proven to be an effective co-catalyst. The conversion of phenol and the yield of DPC were dependent on the amount of ZnCl2 and CF3SO3H, the reaction temperature, and the pressure of CO2. A possible reaction mechanism for the synthesis of DPC catalysed by the co-catalytic system including ZnCl2 and CF3SO3H was also proposed.