Study On Synthesis Of Diphenyl Carbonate And Polycarbonate

High pressure transesterification reaction and process from phenol and dimethyl carbonate?DMC?to methyl phenyl carbonate?MPC?and diphenyl carbonate?DPC?under different reaction condition have been studied in the paper.Also,polycarbonate?PC?catalytic process has been studied from bisphenol A?BPA?and refined and separated DPC.The studies of the transesterification reaction from phenol and DMC to MPC and DPC were carried in the self-designed high pressure distillation device.Based on the type of catalyst,raw material ratio,reaction temperature,reaction time and dosage of catalyst screening and optimization,the optimum condition of the catalytic reaction is:Bu₂SnO/CH₃SO₃H₃ as catalyst,ratio of DMC and phenol is 5:1,reaction temperature is 180?,reaction time is 12h,amount of catalyst for phenol content is0.3%?w?.Under the above process condition,the conversion ratio of phenol is more than 72%,selectivity to methyl phenyl carbonate is more than 99.8%,and methanol content in distillate fractions is above 95%.The catalyst can be easily recycled at least 3 times.DPC has been synthetized from MPC in the optimized condition used the same device.DPC obtained from above process and bisphenol A that are used in the synthesis of polycarbonate.Through the studies of the reaction,the optimized condition has been got as follows:LiOH is selected as a suitable catalyst,prepolymerization temperature is 170?,The pressure of the prepolymerization system is20mmHg-30mmHg,feed ratio of DPC vs bisphenol A is 1.06:1,the dosage of the catalyst is 2×10^-4mol/mol BPA,the polycondensation reaction temperature is 280?,and the polycondensation time is 20 minutes.Polycarbonate molecular weight obtained in the above process conditions is about 20000,the product is colorless and transparent.