反应详情

5 ml of concentrated sulfuric acid were added to a solution of 20.0 g (0.104 moles) of 2,4,5-trifluoro-3-hydroxybenzoic acid [(XXIII), X=X'=F] (prepared as described in Preparation 13) in 500 ml of ethanol, and the mixture was heated under reflux for 4 hours. The ethanol was then removed by distillation under reduced pressure, and the residue was extracted with ethyl acetate. The extract was washed with a saturated aqueous solution of sodium bicarbonate and with water, in that order, after which it was dried over anhydrous sodium sulfate and then concentrated by evaporation under reduced pressure, to give 16.9 g of ethyl 2,4,5-trifluoro-3-hydroxybenzoate as a colorless powder.

1. temperaturethe mixture was heated
2. temperatureunder reflux for 4 hours
3. customThe ethanol was then removed by distillation under reduced pressure
4. extractionthe residue was extracted with ethyl acetate
5. washThe extract was washed with a saturated aqueous solution of sodium bicarbonate and with water, in that order
6. dry with materialafter which it was dried over anhydrous sodium sulfate
7. concentrationconcentrated by evaporation under reduced pressure