The Study Of New Schiff Base Palludium Complexes For Oxidative Carbonylation Of Phenol

Diphenyl carbonate(DPC) as a harmfulless and non-polluting chemical intermediate is the indispensable intermediate for producing polycarbonate by non-phosgene method. There are mainly three methods to synthesize DPC: oxidative carbonylation and phosgene method. Among them, oxidative carbonylation of phenol is a the most valuable industrial route. And the research of oxidative carbonylation process focus on the searching of catalyst with high catalytic performance, mainly. The study show that shicff base palladium complexes which can be synthesized easily showed catalytic activity in the oxidative carbonylation of phenol to DPC. In this paper, a series of Schiff base palladium complexes were synthesized. The catalytic performance of them in oxidative carbonylation of phenol to DPC was investigated and the reaction conditions of some of them were optimized.Three series of Schiff base ligands: salicylaldehyde, o-phenylenediamine, p-aminobenzoic acid, and their palladium complexes were synthesized. The structure of them was characterized by means of UV-vis、FT-IR、1H-NMR and ICP. The catalytic performance of the Schiff base palladium complexes in oxidative carbonylation of phenol to DPC were investigated and the reaction conditions of Pd(S3)2,PdL1 and Pd(D3)2 which showed better catalytic activity were optimized. For Pd(S3)2,PdL1 and Pd(D3)2, under the suitable reaction condition, the yield and selectivity of DPC were 51.7% and 64.9%,48.5% and 72.1%, 53.5% and 68.5%, respectively. A series of supported Pd(D3)2 were synthesized from ZSM-5,MCM-41,SAPO-34,HMS and Hβ,and the structure of them was characterized by the means of FT-IR, XRD, and so on. The catalytic activity of the supported Schiff base palladium complexes in oxidative carbonylation of phenol to DPC were investigated and the reaction conditions of Pd(D3)2/Hβ which showed better catalytic activity were optimized. For Pd(D3)2/Hβ,under the suitable reaction conditions,the yield and selectivity of DPC were 36.1% and 82.2%, respectively.The catalytic performance in oxidative carbonylation of phenol to DPC of homogeneous and heterogeneous Schiff base palladium complexes were compared and the results showed that the structure of Schiff base ligands and the surface area, bore diameter of molecular sieve have effects on the catalytic performance of Schiff base palladium complexes. The Schiff base ligands containing aromatic hydrocarbon showed better catalytic activity than those schiff base ligands only containing aliphatic hydrocarbon(PdS6﹥PdS4).;the catalytic activity of Schiff base palladium complexes will decrease when the Schiff base ligands contain bulk substituent groups(PdL2<Pd L5 and Pd(D2) 2<Pd(D2) 2),which may be caused by the increasing of steric hindrance; the electronic effect of substituent groups on schiff base ligands will effect the catalytic activity of the schiff base palladium complexes too because the electrondrawing groups or electron-donating groups can effect the strength of the coordinate bonds between N,O,Cl with Pd; the surface area and bore diameter of molecular sieves will effect the catalytic performance of supported schiff base palladium complexes,the increasing of the surface area and smaller bore diameter will be conducive to the increasing of the he catalytic performance of supported schiff base palladium complexes in oxidative carbonylation of phenol to DPC.