General procedure for the synthesis of 2-methyl-3-hydroxybenzoic acid from 3-amino-2-methylbenzoic acid: to 5 mL of water containing 0.65 mL of concentrated sulfuric acid, a cold (0°C) suspension of 0.54 g (3.3 mmol) of 2-methyl-3-aminobenzoic acid was added, followed by 0.25 g (3.6 mmol) of solid sodium nitrite. After about 15 minutes of reaction, the mixture was poured into 20 mL of warm water containing 4 mL of concentrated sulfuric acid. The reaction mixture was slowly heated to 90°C and gas was observed to escape. When gas release ceased, the solution was cooled to room temperature and extracted with ethyl acetate. The organic layers were combined, washed with 0.5 N hydrochloric acid, dried and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: 5% dichloromethane solution in methanol) to give 350 mg of white solid (melting point: 137-138°C) in 69% yield.1H NMR (CDCl3) data: δ 8.18 (br.s, 1H), 7.42 (d, J = 7.7 Hz, 1H), 7.13 (t, J = 7.9 Hz, 1H) , 6.93 (d, J = 7.9 Hz, 1H), 2.46 (s, 3H). Elemental analysis (C8H8O3) results: calculated values: C, 63.15; H, 5.29; measured values: C, 63.32; H, 5.36.
