Hydrochloric Acid → 2-Chloro-5-pyridinesulfonyl chloride

Participants

Reaction Steps

Sodium nitrite (3.45 g, 0.05 mol) was added portion wise to a stirred solution of 6-chloro-pyridin-3-ylamine (6.4 g, 0.05 mol) in acetic acid (56 ml) and HCl (conc) (9.92 ml) while maintaining the temperature below 15° C. This solution was then added drop wise to a stirred solution of sulfur dioxide (17.2 g, 0.27 mol), copper (II) chloride (1.85 g, 0.011 mol) and water (2.2 ml) in acetic acid (37 ml) at 5° C. The reaction mixture was allowed to warm to room temperature and poured over ice water and stirred for a further 15 min. The resultant precipitate was collected by filtration, washed with water and dried overnight in a vacuum oven to give 6-chloro-pyridine-3-sulfonyl chloride (6.41 g, 60.5% yield); (400 MHz; d6-DMSO) 8.54 (1H, d), 7.96 (1H, dd), 7.50 (1H, d).

Provenance & Evidence