Synthesis of Aromatic Carbonates by Oxidative Carbonylation: Development of Efficient Palladium Complex Catalyst Systems and Their Application to One-step Polycarbonate Synthesis

摘要

New catalyst systems for the direct synthesis of diphenyl carbonate (DPC) from carbon monoxide (CO) and phenol were investigated. Palladium-tin complexes [Pd_2(dppm)_2(SnCl_3) and Pd_2(dppm)_2(SnCl_3)_2, dppm: bis(diphenylphospino)methane] with manganese redox catalyst [Mn(TMHD)_3, TMHD: 2,2,6,6-tetramethyl-3,5-heptanedionate] were found to produce DPC effedctively without any addition of ammonium halied. Furthermore, palladium catalyst systems such as, palladium dinuclear complexes, palladium-diimine complexes, and palladium-6,6#min#-dimethyl-2,2#min#-bipyridyl complexes promoted the oxidative carbonylation of phenol more effectively in the presence of a ammonium halide. Especially, the efficiencies of Pd_2(Ph_2PPy)_2(NO_2)_2 (Ph_2Ppy:2-pyridyldiphenylphosphine) and Pd(6,6#min#-Me_2bby: 6,6#min#-dimethyl-2,2#min#-bipyridyl) were highest among these palladium complexes. These palladium catalyst systems were applied for the direct synthesis of polycarbonate (PC) from bisphenol A and CO. PC with the number and weight-average molecular weights of 5600 and 12900 respectively, was successfully obtained using Pd(6,6#min#-Me_2bby)Cl_2 catalyst system. These molecular weights were highest among the direct syntheses of PC by oxidative carbonylation.