Hydrochloric Acid → 2-Chloro-5-pyridinesulfonyl chloride

Participants

Reaction Steps

A solution of 10 g (79.2 mmol) of 3-amino-6-chloropyridine in concentrated HCl (16 mL) and glacial acetic acid (89 mL) was cooled to 10° C. in an ice batch. 5.46 g (79.2 mmol) of sodium nitrite were added portionwise keeping the temperature below 15° C. The mixture was stirred for 1 h, then added dropwise to a solution of sulfur dioxide (ca. 27 mL), 2.77 g (16.2 mmol) of copper (II) chloride dihydrate and acetic acid (59 mL) in water (11 mL) over 10 min at 5° C. The reaction mixture was allowed to warm to room temperature and poured over ice/water (300 mL) and stirred for a further 15 min The resultant precipitate was isolated by filtration, washed with water (2×100 mL) and dried under reduced pressure to afford 12.99 g of 6-chloro-pyridine-3-sulfonyl chloride; 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.62 (1 H, d, J=8.31 Hz), 8.26 (1 H, dd, J=8.56, 2.69 Hz), 9.04 (1 H, d, J=2.69 Hz).

Provenance & Evidence