5470-65-5

591-20-8

5470-65-5

Example 1 Synthesis of 3-bromo-4-nitrophenol (Compound 4): concentrated sulfuric acid (98%, 10.0 mL, 187.4 mmol) was slowly added dropwise to a solution of NaNO3 (13.5 g, 159.6 mmol) in water (30 mL), and the reaction temperature was maintained at 0-5°C. Subsequently, a solution of 3-bromophenol (12.0 g, 69.4 mmol) dissolved in ethanol (25 mL). The reaction mixture was stirred overnight at room temperature before being poured into ice water (300 mL) and extracted with dichloromethane (3 × 100 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated, and purified by silica gel column chromatography (eluent: hexane solution of 30% ethyl acetate) to afford the target product, compound 4, in 37.1% yield (5.59 g) as a yellow solid. The structure of the product was confirmed by 1H-NMR (DMSO-d6, 400 MHz), 13C-NMR (CDCl3, 100 MHz) and mass spectrometry (ESI).