Synthesis Of Diphenyl Carbonate Catalyzed By Ionic Liquids

Diphenyl carbonate is an important raw material for the production of polycarbonate,and its traditional synthetic route suffers from the high toxicity of phosgene which would be eliminated in the future.The greener and more environmental friendly routes,transesterification route and CO2 route,were investigated in this paper.The guanidine-based ionic liquids were synthesized,and the bascity strength tuned by adjusting the anion was determined([TMG]Cl<[TMG][BA]<[TMG][Ac]<[TMG][Phe]<[TMG][Im]<[TMG][TFE]).The catalytic activities were tested for the transeterification between the dimethyl carbonate and phenol,the conversion of phenol was less than 4.0%and the yield of diphenyl carbonate was no more than 0.5%under the condition of 160-180 ? and 8 h.The ionic liquids were also applied to the reaction between the dimethyl carbonate and glycerol.Under the optimized reaction conditions:80 ?,catalyst amout of 0.1 mol%,reaction time of 30 min,the TOF could reach 1754.0 h-1(91.8%of glycerol conversion and 95.5%of glycerol carbonate selectivity)and the anion-cation synergistic catalytic mechanism was proposed.The thermodynamic data of diphenyl carbonate was calculated based on the Beson group contribution method and the thermodynamic analysis such as enthalpy change,Gibbs free energy change and equilibrium constant of the reaction between the CO2 and phenol in presence of CCl4 was carried out.It turned out that it was an endothermic reaction and spontaneous to occur under the condition of 100-200 ?,4 MPa.A series of ionic liquids,especially the tertiary amine based ionic liquids,were synthesized and screened as the catalysts.The effect of carbon chain length and the ratio between the tertiary amine salt and zinc chloride in the ionic liquids were investigated.The tripropylamine hydrochloride contained ionic liquid showed the best performance when the ratio between tripropylamine hydrochloride and zinc chloride was 1:2.The reaction conditions such as pressure,temperature and reaction time were also optimized.At 4 MPa,150 ? and 8 h,the phenol conversion and diphenyl carbonate yield were 66.0%and 18.5%,respectively.