Single-step catalytic synthesis of diphenyl carbonate over transition-metal-substituted Keggin-type tungstophosphoric acid

Single-step catalytic synthesis of diphenyl carbonate (DPC) through the transesterification of dimethyl carbonate (DMC) and phenol could be firstly arrived by using the transition-metal-substituted polyoxometalates (TMS-POMs) K5[PW11O39M(H2O)]/TiO2 system (M = MnII, CoII, NiII, CuII, ZnII). The catalytic activity of this transesterification was strongly influenced by the type of transition metal in the TMS-POMs. Among them, the K5[PW11O39Zn(H2O)]/TiO2 catalytic system showed the highest activity and selectivity for DPC. The conversion of phenol reached 12.8%, and the selectivity to DPC was 83.6%. The turnover number (TON) reached 6.44 × 104 mol/mol [PW11O39Zn(H2O)]5−/TiO2. A possible mechanism that the transition metal in the polyoxometalates anchored DMC to form intermediate compound in the transesterification was proposed.