Novel usage of palladium complexes with P-N-P ligands as catalysts for diphenyl carbonate synthesis

Two palladium complexes with P-N-P ligands [Pd{(sPPh(2))(2)N}(2)]{Pd(S,S)} and [Pd{(SePPh)(2)N}(2)] {PPd(Se,Se)} were prepared and investigated as nov el polladium catalysts for oxidative carbonylation of phenol using carbon m onoxide and oxygen along with a redox catalyst (for in situ regeneration of palladium) and ammonium halide, The efficiency of these new catalysts was compared with that of a PdCl2-based catalyst system. In order to obtain the maximum efficiency, the effects of various parameters such as concentratio n of redox catalyst and ammonium halide, the effect of solvent, the influen ce of a quinone-type redox catalyst in addition to inorganic redox catalyst , and the effect of temperature were studied, Under the reaction conditions employed, the Pd(S,S) catalyst was found to perform better than PdCl2-base d catalyst system, whereas the Pd(Se,Se) catalyst had extremely low efficie ncy.