The general procedure for the synthesis of 2-chloro-3-nitro-4-hydroxypyridine from 2,4-dichloro-3-nitropyridine was as follows: 2,4-dichloro-3-nitropyridine (100 g, 518 mmol) was dissolved in N,N-dimethylformamide (500 mL) at room temperature, followed by the addition of sodium acetate (106 g, 1295 mmol). The reaction mixture was heated to 120 °C and stirred continuously for 5 hours. The progress of the reaction was monitored by thin layer chromatography (TLC) and after confirming the completion of the reaction, the mixture was cooled to room temperature. The reaction mixture was diluted with water (500 mL) and the pH was adjusted to less than 4 with aqueous 2N hydrochloric acid.Subsequently, the aqueous layer was extracted several times with ethyl acetate (5 x 750 mL). All organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give the crude product. The crude product was further ground with water, filtered to collect the solid, and dried under vacuum to give 2-chloro-3-nitro-4-hydroxypyridine (63 g, 65% yield). Mass spectrum (ESI) m/z: 175.1 ([M+H]+); 1H NMR (400 MHz, DMSO-d6) δ: 7.10 (d, J=6.0 Hz, 1H), 8.25 (d, J=5.6 Hz, 1H), 13.10 (br s, 1H).
