Synthesis of Diphenyl Carbonate from Phenol and Carbon Dioxide in the Presence of Carbon Tetrachloride and Zinc Chloride

Diphenyl carbonate (DPC) was synthesized from phenol and dense phase CO2 in the presence of CCl4 and K2CO3 using different catalysts of ZnCl2, ZnBr2, Lewis acid ionic liquids including 1-butyl-3-methylimidazolium chloride (BMIMCl) and bromide (BMIMBr). It was found that K2CO3 was not required, ZnCl2 and ZnBr2 were similar in the catalytic performance, and the use of BMIMCl and BMIMBr was not effective for the production of DPC. For the reactions with ZnCl2 in CCl4, the effects of such reaction variables as temperature, CO2 pressure, the amount of ZnCl2, and the volume of CCl4 were studied in detail. It was shown that the pressure was less influential while a larger amount of ZnCl2, a smaller volume of CCl4, and a low temperature of around 100A degrees C were beneficial for the synthesis of DPC. On the basis of the results obtained, possible reaction mechanisms were discussed.