2,3-Difluorobenzoic acid

124-38-9

126163-64-2

4519-39-5

Carbon dioxide gas was passed into a reaction solution containing lithium 2,3-difluorobenzene (CAS:126163-64-2) at a temperature of -65 to -60 °C, ensuring that the molar ratio of carbon dioxide to lithium 2,3-difluorobenzene was 1.5:1. The reaction was maintained at this temperature for 4 hours. Upon completion of the reaction, water was added for hydrolysis at a mass ratio of water to reaction solution of 1.5:1 and the hydrolysis temperature was controlled at 15-20 °C. Subsequently, the organic solvent was removed by heating distillation and the reaction mixture was concentrated. The temperature was adjusted to 20-22 °C and the reaction mixture was acidified with a 10% hydrochloric acid solution with a molar ratio of hydrochloric acid to lithium 2,3-difluorobenzene of 2:1. After acidification, the reaction was kept for 3 hours. The reaction mixture was cooled to 0°C and the crystals formed were collected by diafiltration. The crystals were washed with a buffer solution of pH=2 and subsequently dried to give 2,3-difluorobenzoic acid. The purity of the final product was 99.5% and the yield was 90%.