Preparation Of Schiff Base Palladium Complexs Catalyst For Oxidative Carbonylation Of Phenol To Diphenyl Carbonate

In recent years, research has shown that schiff base metal complexes in analyticalchemistry, biochemistry and catalytic aspects have very widely application. Researchersgradually started to attach great importance to the study of this series of catalysts, and haveachieved much achievements. In this paper, a series of schiff base complexes and metalschiff base complexs catalysts were synthesized. The novel structure of palladium dinuclearand palladium-copper hetero-dinuclear complexes were synthesized by amino acids withspecial structure of the ligand atoms （N,O）. Their structures have been characterized anddetermined and these complexes were used in the oxidative carbonylation phenol todiphenyl carbonate. Effects of some factors on the catalytic performance were investigated,and the reaction conditions were optimized.Synthesis of the four series of ten kinds of schiff base ligands: paratoluidineseries,vanillin series, p-aminobenzoic acid series and amino acids series, include p-hydroxybenzaldehyde-paratoluidine ligands（L₁）, vanillin-paratoluidine ligand （L₂）, p-aminobenzoicacid-salicylaldehyde ligand （L₃）, and their palladium complexes （L₁-L₃） were synthesizedby microwave solvothermal method; Iigands （L₄-L₆） were synthesized by L-leucine/glycine/L-glutamic acid and salicylaldehyde, and dinuclear （Pd₂（L₄-L₆）） and palladium-copper hetero-dinuclear complexes （PdCu（L₄-L₆）） were synthesized;Complexes （Pd（L₁）₂Cl₂、Pd（L₂）₂Cl₂、Pd（L3）₂） and supported amino acids schiff basewere synthesized by microwave solvothermal method. Their structures and performancecharacterization have been characterized and determined by means of FT-IR, UV-vis,¹H-NMR, ICP, XRD, N₂adsorption-desorption, TG-DTA. The catalytic performance of theschiff base complexs in oxidative carbonylation of phenol to diphenyl carbonate （DPC） wasinvestigated. The Pd（L₁）₂Cl₂/PdCuL₄/PdCuL₄/ZSM-5complexes were showed bettercatalytic performance.Compared the catalytic performance of the different kinds of schiff base palladiumcomplexes. The results showed that the ligands type, ligands space structures, substituenttype and amount of complexes, interaction between complexes and molecular sieve play animportant role in the catalytic properties. CO and phenol activation and reactiveintermediates production in the reaction have an important influence on reaction yield and selectivity, and strong alkaline and low affinity of alkali is beneficial to reaction.The catalytic performance of the schiff base complexs in oxidative carbonylation ofphenol to diphenyl carbonate （DPC） was investigated. The effects of reaction temperature,time, pressure and co-catalyst amount on the DPC yield and selectivity in the oxidativecarbonylation were studied. The DPC yield and selectivity was27.35%and66.96%respectively under the appropriate reaction conditions of (Pd（L₁）₂Cl₂:TBAB: H₂BQ=1:50:100(molar, n(Pd²⁺)=0.02mmol)), co-catalyst amount0.04g, reaction temperature90℃, reaction pressure4.5MPa （O2:CO=1:8）, reaction time8h; The DPC yield andselectivity was20.0%and47.3%respectively under the appropriate reaction conditions of(CuPdL₄:TBAB:H2BQ=1:50:100(molar, n(Pd²⁺)=0.02mmol)), co-catalyst amount0.03g,reaction temperature110℃, reaction pressure4.5MPa （O2:CO=1:8）, reaction time8h; TheDPC yield and selectivity was18.3%and47.4%respectively under the appropriate reactionconditions of (CuPdL₄/ZSM-5:TBAB:H₂BQ=1:50:100(molar, n(Pd²⁺)=0.02mmol)), reacti-on temperature100℃, reaction time8h and co-catalyst amount0.03g.