Synthesis
Potassium nitrate (51.5 g, 509 mmol) was slowly added to a mixed solution of concentrated sulfuric acid (32.6 mL) and water (105 mL) at 10 °C. The reaction mixture was stirred for 5 min and then 3-bromophenol (49.35 g, 285 mmol) was added dropwise while the reaction temperature was controlled to be maintained at about 10 °C. After addition, the reaction mixture was continued to be stirred at room temperature for 2 hours. Upon completion of the reaction, the reaction solution was diluted with water (350 mL) and subsequently extracted with ether. The organic layers were combined, washed with saturated saline, dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was purified by fast column chromatography (silica gel, 19:1 hexane/ethyl acetate) to afford 5-bromo-2-nitrophenol (11.3 g, 18% yield) as a yellow-green solid. Its 1H NMR (DMSO-d6, 300 MHz) data were as follows: δ 11.44 (s, 1H), 7.84 (d, J = 8.7 Hz, 1H), 7.33 (d, J = 2.1 Hz, 1H), 7.18 (dd, J = 8.7, 2.1 Hz, 1H).
References
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[4] Patent: WO2011/44134, 2011, A1. Location in patent: Page/Page column 107
[5] Patent: EP1956013, 2008, A1. Location in patent: Page/Page column 37
