Azobisisobutyronitrile → 1,3-Dibromo-2-(bromomethyl)benzene

Participants

Reaction Steps

A 250-mL single-neck round-bottomed flask equipped with a magnetic stirrer, reflux condenser and nitrogen inlet was purged with nitrogen and charged with 2,6-dibromotoluene (2.50 g, 10.0 mmol), N-bromosuccinimide (1.78 g, 10.0 mmol) and carbon tetrachloride (40 mL). The solution was heated to 80° C. (oil bath temperature), and 2,2′-azobisisobutyronitrile (164 mg, 1.00 mmol) was added. The resulting mixture was refluxed for 14 h. After that time, the mixture was cooled to room temperature and filtered. The filter cake was washed with carbon tetrachloride (2×20 mL). The filtrate was diluted with ethyl acetate (200 mL) and washed with water (40 mL), saturated aqueous sodium bicarbonate (40 mL) and brine (40 mL). The organic layer was dried over sodium sulfate and concentrated under reduced pressure to afford a quantative yield (3.28 g) of 1,3-dibromo-2-(bromomethyl)benzene as a yellow solid: mp 77-78° C.; 1H NMR (300 MHz, CDCl3) δ 7.55 (d, 2H, J=8.1 Hz), 7.07 (t, 1H, J=8.1 Hz), 4.83 (s, 2H). A 250-mL single-neck round-bottomed flask equipped with a magnetic stirrer and nitrogen inlet was purged with nitrogen and charged with this residue (3.28 g, 10.0 mmol), potassium acetate (3.93 g, 40.0 mmol) and DMF (100 mL). The solution was stirred at room temperature for 14 h. After that time, the reaction mixture was diluted with water (900 mL) and extracted with ethyl acetate (3×200 mL). The combined organic layers were washed with brine (100 mL), dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography to afford an 88% yield (2.70 g) of 103d as an off-white solid: mp 62-65° C.; 1H NMR (300 MHz, CDCl3) δ 7.57 (d, 2H, J=8.0 Hz), 7.07 (t, 1H, J=7.9 Hz), 5.42 (s, 2H), 2.11 (s, 3H); MS (ESI+) m/z 306.9 (M+H).

Provenance & Evidence