Synthesis of Heat-Resistant Polyester Containing Rigid Biphenyl Moiety by Palladium-Catalyzed Carbonylation-Polycondensation

For the purpose of synthesizing heat-resistant polyesters, the one-step synthesis of a rigid biphenyl-containing polyester from dihalobiphenyl and diol by palladium-catalyzed carbonylation-polycondensation was examined. The reaction parameters, such as the base, solvent, palladium–phosphine catalyst and CO pressure in the reaction of 2,7-dibromo-9,10-dihydrophenanthrene and 4,4′-(1-methylethylidene)bisphenol (bisphenol A), were found to significantly affect the molecular weight of the resulting polyester. Under the optimum conditions, poly[oxy-1,4-phenylene(1-methylethylidene)-1,4-phenyleneoxycarbonyl(9,10-dihydro-2,7-phenanthrenediyl)carbonyl] (1) were obtained in 95% yield with high molecular weight (polystyrene equivalent Mw = 102600). By choosing the phosphine ligands and controlling the pressure of carbon monoxide, polymer 1 was obtained with a Mw of 10000—100000. The procedure was applied to various dihalobiphenyls and diols. Polycondensation with 1,10-decanediol gave poly[oxydecamethyleneoxycarbonyl(9,10-dihydro-2,7-phenanthrenediyl)carbonyl] (15) with a much lower molecular weight (Mw = 4900) than polyester 1. On the basis of a thermal analysis, a 5% weight-loss temperature (T5) and a 10% weight-loss temperature (T10) of 1 in air was 394 and 414 °C, respectively, whereas melting temperature (Tm), T5, and T10 of 15 were 148, 369, and 383 °C, respectively.