In a round-bottom flask (500 mL), add glacial acetic acid (30 mL) and bubble with gaseous sulfur dioxide for 30 minutes. Add an aqueous solution of copper chloride (1.5 g, 10 mL) to the solution to obtain a suspension of copper chloride (suspension A). Dissolve an appropriate amount of fluoro-2-fluoroaniline (1.5 g) in a mixture of glacial acetic acid (30 mL) and 12N hydrochloric acid (15 mL) in another flask, and cool the resulting solution (solution B) in an ice/salt bath. Add an aqueous solution of sodium nitrite (2.5 g) (10 mL) dropwise to solution B. Slowly add the resulting mixture to suspension A and stir in an ice bath for 15 minutes. Pour the reaction mixture into water (200 mL) and ether (200 mL), separate the organic layer, and concentrate under reduced pressure to dryness to obtain the target product.
Figure 2, Synthetic route of 2,6-Difluorobenzenesulfonyl chloride
