5409-39-2

21427-62-3

(Step 1) 5-Chloro-3-nitropyridin-2-amine (10.0 g, 57.6 mmol) was dissolved in concentrated hydrochloric acid (100 mL), cooled to -10 °C and stirred continuously. An aqueous solution of sodium nitrite (9.94 g, 144 mmol) was slowly added dropwise (20 mL) over 30 min. After the dropwise addition, the reaction mixture was kept at 0 °C with continued stirring for 1 hour. Subsequently, the pH of the reaction solution was adjusted to 9 with 1N aqueous sodium hydroxide solution and then extracted with ethyl acetate. Insoluble impurities were removed by filtration and the organic layer was washed with saturated brine and dried with anhydrous magnesium sulfate. After filtration, the solvent was removed by distillation under reduced pressure to afford the target product 2,5-dichloro-3-nitropyridine (6.50 g, yield: 58.5%) as a solid.1H-NMR (CDCl3) δ: 8.60 (1H, d, J = 2.9 Hz), 8.24 (1H, d, J = 2.6 Hz).