The general procedure for the synthesis of 1,3,5-trifluoro-2,4,6-triiodobenzene from 1,3,5-trifluorobenzene was as follows: potassium iodide (KI, 7.14 g, 43.56 mmol) was slowly added to a stirring mixture of periodate (3.30 g, 14.50 mmol) and concentrated sulfuric acid (20 mL) at 0 °C. The resulting dark-colored mixture was cooled in an ice bath while 1,3,5-trifluorobenzene (1.0 mL, 9.68 mmol) was added dropwise over 25 min. Subsequently, the reaction mixture was heated to 70 °C and maintained at this temperature for 4 hours. After completion of the reaction, the mixture was cooled to room temperature and poured into ice water. Extraction was carried out with ether (3 x 50 mL) and the organic phases were combined. The organic phase was washed sequentially with saturated aqueous sodium bicarbonate (NaHCO3), aqueous sodium thiosulfate (Na2S2O3) and distilled water, and then dried with anhydrous sodium sulfate (Na2SO4). After evaporation to remove the solvent, the pure white powdery product 1,3,5-trifluoro-2,4,6-triiodobenzene was obtained in 80% yield. The product was characterized as follows: 19F NMR (CDCl3, 235MHz): δ-69.90ppm; melting point: 158-159°C; FT-IR (KBr pressed sheet, cm-1): 1561, 1401, 1325, 1048, 704, 652.
