Study On Synthesis Of Terephthaloyl Dichloride By Phase Transfer Catalysis

In the paper,phase transfer catalyst and polymer-supported catalyst were used for the synthesis of terephthaloyl dichloride from terephthalic acid and thionyl chloride.Firstly,effects of catalysts,solvents,solvent,reaction temperature,reaction time on yield and purity of the product were studied and the best response condition to the response determined.The reaction mechanism was proposed.The suited conditions were determined as:the mole ratio of thionyl chloride to terephthalic acid was 4:1, the reaction temperature was 85℃and reaction time was 4h under solvent-free condition.The yield and purity of terephthaloyl dichloride was not less than 96%and the purity was not less than 98.8%.Secondly,four kinds of new polymer-supported catalysts were synthesized under the improved conditions,and were analyzed and attributed by IR and content determination.The catalytic system was used for the acyl chloride reaction of terephthalic acid,and the reaction mechanisms were discussed.The reaction conditions optimized are as follows:terephthalic acid 16.6g,SOCl₂ 30mL,toluene 32mL,dosage of catalyst 3g,time 6h and temperature 85℃.Under the optimized condition,yield was 89.6%and the purity of terephthaloyl dichloride was 99.6%, with the catalyst recovery 93.6%.The catalytic activity remained stable after the six recycles.The structure of the target product was identified by melting point determination, IR and 'H-NMR.A reversed phase high performance liquid chromatographic method with pre-column derivation was described for analyzing medical intermediate terephthaloyl dichloride.The SunFire C18 column was used with the mobile phase of methanol and water.The relative standard deviation and average recovery was 0.1490%and 99.53%.