Hydrogen Bromide → 2-Bromo-5-chloro-3-nitropyridine

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Reaction Steps

To a stirred, ice bath cooled solution of HBr (48%, 214 mL, d=1.49, 1.89 mol) was added 2-amino-5-chloro-3-nitropyridine (2) (66.0 g, 376 mmol). The mixture was stirred until the internal temperature was less than 0° C., and then bromine (65 mL, d=3.102, 1.3 mol) was added dropwise. The resulting orange mixture was stirred at a temperature below 0° C. A solution of NaNO2 (91.3 g, 1.32 mol, used as received) in water (125 mL) was added slowly to the mixture so as to maintain the internal temperature below 0° C. The mixture was stirred for an additional 45 min at below 0° C., and then NaOH (139.3 g, 3.482 mol) in water (200 mL) was slowly added to the mixture to maintain the internal temperature below 20° C. The mixture was stirred at below 20° C. for an additional hour, and then gravity filtered. The recovered brown solid was dried at 25° C. under vacuum for 6 h. It was purified by recrystalization from 95% ethanol to obtain 103 as a yellow solid (46.0 g, 51.5%), mp 68°-73° C. (Lit., 75° C., Berrie et al., J. Chem. Soc. 2042 (1952)); 1H NMR (CDCl3): δ8.15 (d, J=2.1 Hz, 1H), 8,57 (d, J=2.1 Hz, 1H).

Provenance & Evidence