5-Bromo-2-furfuraldehyde is a light yellow powder, soluble in carbon dichloride , carbon tetrachloride, ether and other organic solvents.
A three-necked 50 mL round bottom flask was charged with [bmim]Br3 (20 mmol) followed by dropwise addition of freshly distilled 2-furfural (20 mmol) over a period of 0.5 h and the reaction mixture was stirred for at 40 ℃ 2.5 h under nitrogen atmosphere. The mixture was extracted with petroleum ether (30 mL × 3), the organic layer was washed with water, dried (sodium sulfate) and concentrated. The crude product was purified by distillation and recrystallization with 10 % ethyl acetate-ether solution.
5-Bromo-2-furfural of yellowish crystal in 88 % yield was obtained. Mp. 82-85 ℃, 1H NMR (CDCl3), δ: 9.55 (s, 1H), 7.25 (s, 1H), 6.57 (s, 1H).
