Under argon protection, 5-bromo-2-fluoroaniline (45.6 g, 240 mmol) was dissolved in water (120 mL), stirred and concentrated hydrochloric acid (120 mL) was added slowly. After the reaction mixture was cooled to -20 °C, aqueous sodium nitrite (19.9 g, 288 mmol dissolved in 80 mL of water) was added dropwise. Stirring was continued at -20 °C for 20 min, followed by the addition of aqueous potassium iodide solution (59.8 g, 360 mmol dissolved in 60 mL of water) and stirring was continued for 30 min. After completion of the reaction, the reaction mixture was extracted with hexane and the organic layer was washed sequentially with saturated aqueous sodium bicarbonate and sodium sulfite solutions and dried over anhydrous sodium sulfate. After evaporation of the solvent under reduced pressure, the residue was purified by silica gel column chromatography to afford 5-bromo-2-fluoroiodobenzene (54.6 g, 181 mmol) in 76% yield.
