Influence of coordination groups on the catalytic performances of organo-titanium compounds for disproportionation of methyl phenyl carbonate to synthesize diphenyl carbonate

Abstract

The disproportionation of methyl phenyl carbonate (MPC) to synthesize diphenyl carbonate (DPC) catalyzed by organo-titanium compounds with different coordination groups was systematically investigated. The results of the molecular structure analysis, the catalytic performance evaluation and the chemical computational studies revealed that both the electron effect and steric hindrance of the coordination groups together affected the active Ti center and therefore influenced the catalytic performance of the catalysts. The influence of the electron effect was more important than the steric hindrance. The catalytic activity is in the order of Ti(O-iC3H7)4>Ti(OC6H5)4>Ti(OC4H9)4>TiO(OOCCH3)2>TiO(acac)2>Cp2TiCl2, and Ti(O-iC3H7)4 exhibited the best catalytic performance, due to its appropriate steric hindrance and electron effect for the coordination group. Under the optimum condition (n(Cat.)/n(MPC)=0.04, reacted at 180°C for 3h), the MPC conversion of 90.4% and DPC selectivity of 99.6% were attained, respectively, which are comparable to those of other catalysts reported. Moreover, the catalyst is low cost, non-toxic and easily obtained by readily commercial-available purchase, and this catalytic system is also easy operation and convenient-controllable, indicating that it is conducive to future industrial application. In addition, a possible reaction mechanism catalyzed by the organo-titanium compounds with Lewis acid was also proposed for the process.