Wang Gongying

High selectivity to diphenyl carbonate synthesized via transesterification between dimethyl carbonate and phenol with C 60 -doped TiO 2

An environmentally friendly heterogeneous catalyst, C60-doped TiO2(denoted as C60-TiO2), was prepared and firstly used to catalyze the synthesis of diphenyl carbonate(DPC) via the transesterification of phenol and dimethyl carbonate(DMC). The characterization results of FTIR, XRD, XPS, SEM, TEM and digital optical microscope(MIC) show that C60 promotes the dispersion of TiO2 and the prepared conditions affect the dispersion and the electron density of Ti species. The C60-TiO2-8[n(Ti):n(C60)=8:1] prepared with toluene and calcined at 200 °C exhibits the best catalytic performance. The DPC selectivity of 86.5% attained over C60-TiO2-8 was much higher than that(about 50%) attained over Ti-based catalysts reported, which was originated from the electronic effect of C60 and the efficient dispersion of Ti species by C60. The phenol conversion slowly decreased from 34.4% to 26.7% after four consecutive runs due to the leach of Ti species. It also suggested that the C60 could relieve the leach of Ti species compared with other Ti-based catalysts reported. Moreover, C60-TiO2-8 exhibited excellent catalytic behavior for disproportionation of methyl phenyl carbonate(MPC) with high DPC selectivity.

Synthesis of Polycarbonate Diols(PCDLs) via Two-step Process Using CH 3 COONa as an Effective Catalyst

Polycarbonate diols(PCDLs) with a number average molecular weight(Mn) of 2800 and a narrow polydispersity index(PDI=1.33) were synthesized from dimethyl carbonate(DMC) and 1,4-butanediol(BD) via a two-step process. The influences of the molar ratios of DMC to BD in the feedstock, polycondensation temperature and polycondensation time on the PCDLs preparation were studied. CH3COONa showed the best catalytic performance among the catalysts studied. The highest BD conversion of 73.8% and PCDLs yield of 64.7% were achieved under its optimum reaction conditions. Furthermore, based on the results of 1H NMR, the relationships between the ratio of end groups (—OCH3/—OH) of oligomers, the Mn and chainend constitute of resultant polycarbonates were also investigated. The results indicate that PCDLs can be synthesized when the oligomers mostly bear hydroxyl end groups. In contrast, it was impossible to prepare PCDLs when the oligomers were enriched with methyl carbonate end groups.