General procedure for the synthesis of 2,3-difluorobenzotrifluoride from 2-chloro-3-fluorobenzotrifluoride: First, 11,490 g of DMI (1,3-dimethyl-2-imidazolidinone) was added as a solvent to a reactor, followed by the addition of 20 L of fluoroalkyl compounds, 1,125 g of high-purity water, spray-dried KF (potassium fluoride), 35 g of 18-crown ether-6, and 805 g of toluene. Reduced pressure distillation was carried out to remove toluene and further purified using azeotropy with water. Subsequently, the clear grade fraction was dried with high purity nitrogen. 93.1% pure 3-fluoro-2-chlorobenzotrifluoride (134% dosage with toluene as solvent) was heated to 230°C and the reaction lasted for 8 hours. After completion of the reaction, distillation was carried out under reduced pressure (0.01 to 0.02 MPa) and the fractions from 44 to 46 °C were collected to give 1184.8 g of 2,3-difluorobenzotrifluoride, with a product purity of 98.9% and a yield of 95.9%.
