The general procedure for the synthesis of 5-bromo-2-hydroxy-4-methylpyridine using 2-amino-5-bromo-4-methylpyridine as starting material was as follows: an aqueous solution (14 ml) of sodium nitrite (5.44 g, 78.8 mmol) was added slowly and dropwise at 0-5°C to 20% of a 20% solution containing 2-amino-5-bromo-4-methylpyridine (12.83 g, 68.6 mmol) in sulfuric acid solution (69 ml). The reaction mixture was stirred at 0°C for 1 hour and then heated to reflux for 1 hour. Subsequently, the reaction solution was alkalized to pH 10 with 40% sodium hydroxide solution and after cooling to 5°C, the precipitated product was isolated by filtration. The product was recrystallized from ethanol to give 5-bromo-2-hydroxy-4-methylpyridine (5.97 g, 31% yield) as white needle-like crystals (melting point 200°-201°C). NMR hydrogen spectrum (D6-DMSO) δH: 2.17 (3H, single peak, CH3), 6.40 (1H, single peak, 3-H), 7.76 (1H, single peak, 6-H), 11.58 (1H, single peak, NH). Mass spectrum (EI) m/z: 189 (M+, 100%), 187 (M+, 97%). Measured molecular weight: 186.9634 (theoretical molecular weight of C6H6NOBr is 186.9633).
