2,5-Dibromo-3-nitropyridine is used as organic synthesis intermediate and pharmaceutical intermediate, mainly used in laboratory research and development process and chemical production process.
synthesis of 2,5-Dibromo-3-nitropyridine: To a suspension 5-bromo-3-nitro-pyridin-2-ol (20 g, 91.32 mmol) in toluene (100 ml) was added DMF (0.7 ml, 9.13 mmol) and the mixture was heated to 90C. (the reaction mixture was protected from light). A solution of POBr3 (31. 41 g, 109.51 mmol) in toluene (40 ml) was added dropwise at 90C. and the reaction mixture was stirred at that temperature for 16 h. The mixture was allowed to cool to room temperature and toluene (50 ml) and water (50 ml) were added. The organic layer was separated, washed successively with aqueous 1N NaOH (60 ml), water (60 ml) and brine (30 ml), dried with Na2SO4 and evaporated obtain 2,5-Dibromo-3-nitropyridine. Yellow solid, yield 25.2 g, 97%.
(1) Preparation of 2,5-dibromo-3-nitropyridine: 5-bromo-3-nitropyridin-2-amine (5.0 g, 22.9 mmol) was slowly added dropwise to a stirring aqueous hydrogen bromide solution (48%, 13 mL) at 0 °C, keeping the internal temperature of the reaction system not exceeding 5 °C. The reaction was completed by the addition of liquid bromine (4.69 mL) and sodium sulfite (6.32 g). After the dropwise addition, liquid bromine (4.69 mL) and sodium sulfite (6.32 g) were added sequentially. The reaction mixture was continued to be stirred at 0 °C for 45 min, followed by the addition of aqueous sodium hydroxide (9.16 g dissolved in 10 mL of water). The reaction system was brought to room temperature and stirred for 1 hour. Upon completion of the reaction, the precipitated solid product was collected by filtration, washed thoroughly with water and dried to give 2,5-dibromo-3-nitropyridine (3.80 g, 58.9% yield).
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