反应详情

A solution of KMnO4 (39.3 g, 249 mmol) in water (600 mL) was added slowly to a solution of (3-bromo-5-methylphenyl)methanol (25.0 g, 124 mmol) in acetone (500 mL), then the mixture was kept at reflux for 60 min. After cooled to room temperature, the mixture was acidified with HCl (2N, 100 mL). The brown precipitate was dissolved by adding a solution of saturated sodium bicarbonate (100 mL), and then acetone was concentrated in vacuum. Ammonia (150 mL) was added. The mixture was filtered over Celite and acidified with concentrated HCl. The product was extracted with diethyl ether (3×150 mL), the combined organic phases were dried (Na2SO4) and concentrated in vacuum to obtain 16.0 g of the acid 3-bromo-5-methylbenzoic acid as white crystals (yield: 60%). 1H NMR (400 MHz, CDCl3): δ 8.05 (s, 1 H), 7.85-7.84 (m, 1 H), 7.58 (s, 1 H), 2.40 (s, 3 H).

1. temperatureat reflux for 60 min
2. dissolutionThe brown precipitate was dissolved
3. concentrationacetone was concentrated in vacuum
4. additionAmmonia (150 mL) was added
5. filtrationThe mixture was filtered over Celite
6. extractionThe product was extracted with diethyl ether (3×150 mL)
7. dry with materialthe combined organic phases were dried (Na2SO4)
8. concentrationconcentrated in vacuum