Hydrochloric Acid → 2-Bromopyridine-3-carboxylic acid

Participants

Reaction Steps

Potassium permanganate (18.4 g, 116 mmol) was dissolved in water (400 mL) and added to 2-bromo-3-methylpyridine (10.0 g, 58 mmol) and refluxed for 16 hours. After cooling to room temperature, the slurry was filtered through a celite plug and rinsed with water and chloroform. The entire filtrate was transferred to a separatory funnel and the layers were separated. The aqueous layer was extracted again with CHCl3 and acidified with 6N HCl to pH 1. A white solid was obtained on standing (2.08 g of product). The pH of the remaining aqueous was adjusted to pH 4 with 2M NaOH and 2M HCl, then concentrated to <100 mL. A white precipitate was filtered. The pH was adjusted to 4 and the mixture filtered again, combining the isolated solids for a total of 3.88 g of product. The filtrate was concentrated again to <100 mL and adjusted to pH 1.5 and an additional quanitity of white solid was obtained (1.80 g), for a combined yield of 3 crops, (8.76 g, 66%). 1H NMR (DMSO-d6): δ13.76 (bs, 1H), 8.46 (m, 1H), 8.09 (dd, 1H, J=7.7, J′=2.2), 7.51 (m, 1H).

Provenance & Evidence