反应详情

温度

80 °C

A saturated aqueous solution of potassium permanganate (61.3 g, 388 mmol) was added in portions to a well stirred solution of 3,4-dibromotoluene (40.4 g, 162 mmol) in acetic acid (700 mL) while maintaining the temperature between 70 and 80° C. After addition, the suspension was stirred for an additional 4 hours at 80° C. The solution was concentrated on a rotary evaporator, the residue treated with 5 N NaOH (700 mL) and heated under reflux for 2 hours. The MnO2 cake was filtered from solution and washed thoroughly with hot water. The filtrate was extracted with hexane (2×100 mL) and acidified with concentrated HCl pH 2. Collected white precipitate by filtration. Washed precipitate with water and dried under high vacuum. Obtained 16.59 gram (37% yield) of 3,4-dibromobenzoic acid. 1H NMR (300 MHz, DMSO-d6): δ13.47 (singlet, 1H), 8.14 (singlet, 1H), 7.88 (doublet, J=8.1 Hz, 1H), 7.99 (doublet, J=8.1 Hz, 1H). 13C NMR (300 MHz, DMSO-d6): δ165.72, 134.42, 134.18, 132.07, 129.96, 129.32, 124.40.

1. temperaturewhile maintaining the temperature between 70 and 80° C
2. additionAfter addition
3. concentrationThe solution was concentrated on a rotary evaporator
4. additionthe residue treated with 5 N NaOH (700 mL)
5. temperatureheated
6. temperatureunder reflux for 2 hours
7. filtrationThe MnO2 cake was filtered from solution
8. washwashed thoroughly with hot water
9. extractionThe filtrate was extracted with hexane (2×100 mL)
10. customCollected white precipitate
11. filtrationby filtration
12. washWashed precipitate with water
13. customdried under high vacuum