2,6-Diiodopyridine

626-05-1

53710-17-1

General procedure for the synthesis of 2,6-diiodopyridine from 2,6-dibromopyridine: A mixture of 2,6-dibromopyridine (4.83 g, 20.4 mmol), sodium iodide (NaI, 4.00 g, 26.7 mmol, 1.3 eq.), and a 57% aqueous hydriodic acid (HI, 15 mL, 0.20 mol, 9.8 eq.) in water was placed in a sealed tube suitable for a high pressure reaction in a sealed tube and stirred at 140°C for 12 hours. Upon completion of the reaction, the resulting yellow slurry was cooled to room temperature and the reaction mixture was poured into crushed ice (which could be remelted using a hot air gun if necessary). The pH of the mixture was adjusted to neutral with concentrated aqueous sodium hydroxide, followed by extraction with ether (Et2O, 3 × 200 mL). The organic extracts were combined, washed sequentially with saturated aqueous sodium bicarbonate (NaHCO3, 50 mL) and saturated aqueous sodium bisulfite (NaHSO3, 50 mL), dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. Purification was carried out by dry column vacuum chromatography (0-10% ethyl acetate/heptane, 1% increments, 100 mL steps), and finally recrystallized from boiling heptane to afford the target product 2,6-diiodopyridine (3.33 g, 20.4 mmol, 49% yield) as colorless fine needle-like crystals.