2,3-Difluoro-5-(trifluoromethyl)pyridine

69045-84-7

89402-42-6

The general procedure for the synthesis of 2,3-dichloro-5-trifluoromethylpyridine from 2,3-dichloro-5-trifluoromethylpyridine is as follows: 1500 mL of DMSO, 363 g of cesium fluoride, and 8 g of potassium carbonate were added to a 5000 mL reaction flask and heated in an oil bath. Concentrate and cool 600 mL of DMSO under reduced pressure to below 80 °C. Under nitrogen protection, 318 g (1.58 mol) of 2,3-dichloro-5-trifluoromethylpyridine was added to the reaction system and the reaction was carried out at about 110 °C for 48 hours. After completion of the reaction, 600 mL of water was added to the yellow liquid for liquid-liquid separation. The organic phase was dried with anhydrous magnesium sulfate and filtered to give a crude product of 188 g. The 100-102 °C fractions were collected by distillation to give 139 g of 2,3-difluoro-5-trifluoromethylpyridine in 47.6% yield.