6-Bromonicotinic acid

3510-66-5

6311-35-9

General procedure for the synthesis of 6-bromonicotinic acid from 2-bromo-5-methylpyridine: 2-bromo-5-methylpyridine (100 g, 0.291 mol) was dissolved in 1000 mL of water and Aliquat 336 (2 mL) was added as a phase transfer catalyst. Subsequently, potassium permanganate (251 g, 0.797 mol) was added slowly over 1 hr. The reaction mixture was stirred at 110 °C for 30 min and continued for 1 h to ensure complete reaction. Upon completion of the reaction, the mixture was filtered through diatomaceous earth while hot and the diatomaceous earth was washed with hot water. The filtrate was concentrated to half the original volume under reduced pressure. To the concentrate was added 48% hydrobromic acid (about 300 mL), and the precipitated 6-bromonicotinic acid crystals were filtered, washed with water and dried to give 52 g of white crystals in 44% yield. The product was characterized by 1H-NMR (CDCl3) with chemical shift δ (ppm) of 7.64 (1H, d, J = 8.0 Hz), 8.08 (1H, d, J = 8.0 Hz), 9.03 (1H, s).