3-Chloro-5-(trifluoromethyl)pyridine

69045-84-7

85148-26-1

The general procedure for the synthesis of 3-chloro-5-trifluoromethylpyridine using 2,3-dichloro-5-trifluoromethylpyridine as starting material was as follows: zinc powder (1.18 g, 18.0 mmol) was added to a suspension of 2,3-dichloro-5-trifluoromethylpyridine (2.0 g, 9.30 mmol) in a solvent mixture of 80:20 (v/v) water and acetic acid (5 mL) at 90° C with stirring for 1 hour. Subsequently, zinc powder (1 g, 15.3 mmol) was made up and stirring was continued at 90°C for 15 minutes. After completion of the reaction, the mixture was cooled to room temperature, filtered and the filtrate was washed with dichloromethane. The filtrate was carefully concentrated and the residue was purified by silica gel column chromatography with an elution gradient of 100:0 to 0:100 (v/v) hexane:dichloromethane, resulting in 3-chloro-5-trifluoromethylpyridine as a colorless oil (0.120 g, 7% yield). The product was characterized by 1H NMR (300 MHz, CDCl3): δ 7.93 (s, 1H), 8.78 (s, 2H); GC-MS (EI) analysis showed m/z = 181.0, 183.0 [M].