The general procedure for the synthesis of 3-bromo-4-iodobenzotrifluoride from 2-bromo-4-(trifluoromethyl)aniline and potassium iodide was as follows: 2-bromo-4-(trifluoromethyl)aniline (3.00 g, 12.50 mmol) and concentrated hydrochloric acid (15 mL) were added to a solvent mixture of acetonitrile (30 mL) and water (10 mL), and cooled to -10°C. At -10°C, a slow solution of sodium nitrite (0.95 g, 13.75 mmol) in water (5 mL) was added dropwise. The resulting reaction mixture was stirred at -10°C for 30 minutes, then a solution of potassium iodide (2.49 g, 15.00 mmol) in water (5 mL) was added and stirring was continued for 2 hours, then the reaction mixture was allowed to slowly warm to room temperature and reacted overnight. Upon completion of the reaction, saturated sodium bicarbonate solution (30 mL) was added to the reaction mixture and extracted with dichloromethane (50 mL x 3). The organic phases were combined and washed sequentially with saturated sodium thiosulfate solution (30 mL) and saturated brine (30 mL). The organic phase was separated, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (petroleum ether as eluent) to afford 3-bromo-4-iodobenzotrifluoride as a yellow oily liquid (3.95 g, 90.0% yield).
