反应详情

2-Bromo-6-fluoro-5-trifluoromethylbenzoic acid 50 mmol of 4-bromo-2-fluoro-1-trifluoromethoxybenzene [105529-58-6] are added at −75° C. to a solution of 52.5 mmol of diisopropylamine and 52.5 mmol of n-butyllithium (1.6 M solution in n-hexane) in 100 ml of dry tetrahydrofuran. The reaction mixture is left at this temperature for 2 h and then added to dry ice. Hydrolysis is effected using water, acidification with hydrochloric acid and extraction with tert-butyl methylether. The combined organic extracts are washed with saturated sodium chloride solution and dried over sodium sulfate. After removing the solvent under reduced pressure, the crude product is purified by recrystallization from n-heptane. 2-Bromo-6-fluoro-5-trifluoromethoxybenzoic acid is obtained in the form of colorless crystals. Melting point: 112° C. 1H NMR (300 MHz, DMSO-d6/TMS): δ=7.67 and 7.71 (overlapping multiplets, 2H)—19F NMR (282.4 MHz, 1H broadband decoupled, DMSO-d6/CFCl3): δ=−57.6 (d, 5J(FF)=5 Hz, OCF3), 129.0 (q, 5J(FF)=5 Hz, CF).

1. customHydrolysis
2. extractionwith hydrochloric acid and extraction with tert-butyl methylether
3. washThe combined organic extracts are washed with saturated sodium chloride solution
4. dry with materialdried over sodium sulfate
5. customAfter removing the solvent under reduced pressure
6. customthe crude product is purified by recrystallization from n-heptane