DIRECT POLYCONDENSATION OF HYDROXYBENZOIC ACIDS WITH THIONYL CHLORIDE IN PYRIDINE

The reaction promoted by thionyl chloride and pyridine could selectively activate carboxyl groups of hydroxybenzoic acids to give polyesters of high inherent viscosities up to 3. 8. Favorable conditions were studied in terms of the temperatures for the initial reaction with the acids and subsequent aging at room temperature. Copolymers of several combinations of hydroxybenzoic acids with high molecular weights were obtained in quantitative yield by carrying out the polycondensation at 80 degree C for 3 h. The reaction could also produce high molecular polyesters in a simpler process without the initial activation of dicarboxylic acids by adding a mixture of these monomers of the condensing agent, and a tough film- and fiberforming polymer was obtained from 4,4'-dihydroxphenylsulfone of low nucleophilicity whose polymer of high molecular weight is difficult to obtain.