General procedure for the synthesis of 4-iodo-3-(trifluoromethyl)benzoic acid from 3-trifluoromethyl-4-aminobenzoic acid: 4-amino-3-trifluoromethylbenzoic acid (1.8 g, 8.8 mmol) was suspended in 30 mL of hydrochloric acid. An aqueous solution (15 mL) of sodium nitrite (0.76 g, 11.0 mmol) was slowly added dropwise at 0°C. The reaction mixture was stirred at 0-10 °C for 30 min. Subsequently, an aqueous solution (25 mL) of potassium iodide (14.6 g, 88 mmol) was added dropwise. The mixture was stirred at room temperature for 1 hour. After completion of the reaction, the product was extracted with ethyl acetate (80 mL) and the organic layer was washed with brine (80 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give the crude product. The crude product was purified by fast chromatography using a gradient elution with ethyl acetate/hexane, resulting in 4-iodo-3-(trifluoromethyl)benzoic acid (2.4 g, 86% yield) as a solid.LC-ES/MS analysis showed m/e 339.3 (M+23) and 315.0 (M-1).
