Chlorosulfonic acid → 2-Amino-5-bromopyridine-3-sulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

5-Bromo-pyridin-2-ylamine (10 g, 57.8 mmol) was added to chlorosulfonic acid (40 mL, 602 mmol) while stirring at 25° C. The mixture was heated at 160° C. while stirring for 3 h. Upon cooling to 25° C., the brown solution was carefully poured over ice (˜500 g). The resulting precipitate was collected by vacuum filtration and rinsed with water to afford the intermediate, 2-amino-5-bromo-pyridine-3-sulfonyl chloride, as a beige solid. The solid was suspended in a 15% aqueous ammonium hydroxide solution. The reaction mixture stirred for 45 min. Everything was completely dissolved at this point. The mixture was cooled to 0° C. and the pH was adjusted to ˜8 by the careful addition of 12.0 M aqueous hydrochloric acid solution. A solid precipitated and was collected by vacuum filtration, rinsed with water (2×50 mL) and dried in vacuo to afford the desired product, 2-amino-5-bromo-pyridine-3-sulfonic acid amide (7.48 g, 29.7 mmol, 51%), as a light beige solid. 1H NMR (400 MHz, DMSO-d6) δ: 6.69 (2H, bs), 7.54 (2H, bs), 7.91 (1H, d, J=2.5 Hz), 8.22 (1H, d, J=2.3 Hz).

Provenance & Evidence