Hydrochloric Acid → 5-Bromo-3,4-dihydroxybenzaldehyde

Participants

Reaction Steps

To a vigorously stirred suspension of 3-bromo4-hydroxy-5-methoxy-benzaldehyde (15.20 g, 65.8 mmol), AlCl3 (9.65 g, 72.4 mmol) in CH2Cl2 (100 mL) at 0° C. with exclusion of moisture was added pyridine (22.90 g, 290 mmol, 23.4 mL) to keep the temperature below 32° C. The resulting clear dark solution was heated to reflux for 24 hours and cooled to RT. The mixture was poured into a slurry of 1 N HCl and ice. The CH2Cl2 layer was removed and the aqueous suspension was extracted with ether till clear. The combined ether layers were dried over anhydrous magnesium sulfate, filtered and evaporated to a volume of approximately 200 mL and cooled to 0° C. for 2 hours. The resulting suspension was collected by filtration and dried under high vacuum to give 10.12 g of 3-bromo-4,5-dihydroxybenzaldehyde (71%) as a tan solid. 1H NMR (500 MHz; CDCl3): δ 7.18 (s, 1H); 7.37 (d, J=2.0 Hz, 1H); 8.48 (brs, 1H); 9.40 (brs, 1H); 9.56 (s, 1H).

Provenance & Evidence