METHOD OF SYNTHESIS OF 2,5-BIPHENYLDICARBOXYLIC ACID Russian patent published in 1997 - IPC

FIELD: organic chemistry and technology. SUBSTANCE: product: 2,5-biphenyldicarboxylic (phenylterephthalic) acid. Method involves alkylation of p-xylene with cyclohexanol followed by dehydrogenation of cyclohexyl-p-xylene formed, oxidation of 2,5-dimethylbiphenyl and isolation of the end product. Oxidation of 2,5-dimethylbiphenyl is carried out in liquid phase with oxygen or air in acetic acid medium at the parent concentration of 2,5-dimethylbiphenyl 0.1-1.0 M in the presence of catalytical system consisting of cobalt acetate, manganese acetate, sodium bromide at molar ratio = (5-50): (1-2.5): (5-50), at 80-110 C for 3-6 h followed by crystallization. Synthesized 2,5-biphenyldicarboxylic acid is purified by its dissolving in an aqueous ammonia and precipitation of the formed ammonium salt with dioxane, salt dissolving in water and acidification with hydrochloric acid. Synthesized compound can be used for production of thermotropic mesomorphic polyesters. EFFECT: increased yield and quality of product. 1 tbl