Synthesis of high-purity 2-hydroxyterephthalic acid

2-hydroxyterephthalic acid（HTA）was synthesized by modified Koble-Schmitt atmospheric carboxylation method. and refined. The new synthesis method was compared with 2-bromoterephthalic acid（BTA）catalytic hydrolysis. The results showed that crude product HTA with purity of 90% was prepared from HBA by CO₂ atmospheric carboxylation for 6 h at 230—240 ℃ in the presence of K₂CO₃ and potassium formate solvent，and purified through two times acid-alkali refining to obtain polymerization-grade HTA with high-purity of 99.5 % and metal ions of below 50 mg/kg，total yield of  above 56%（base on HBA）. The prepared HTA was identified by FT-IR and MS，and the process had the advantages of atmospheric carboxylation，convenient operation，excellent product quality，good economy and easy commercialization. The prepared HTA could provide the raw material for new high-preformance materials modified with hydroxy group and new monomers.