反应详情

9.82 g (44.6 mmol) of the above O-ethoxycarbonyl-2,3,4-trifluorophenol was dissolved in 25 mL of concentrated sulfuric acid under ice-cooling, 8.0 mL of fuming nitric acid was added at an internal temperature of 50° C. or below and the mixture was further stirred for 2 hours. The reaction solution was poured into 300 mL of ice water and the mixture was extracted once with ethyl acetate. The organic layer was washed once with water and twice with an aqueous saturated solution of sodium chloride and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (n-hexane:ethyl acetate=20:1) to give 1.44 g of O-ethoxycarbonyl-2,3,4-trifluoro-5-nitrophenol (yield: 12%)

1. temperaturecooling
2. extractionthe mixture was extracted once with ethyl acetate
3. washThe organic layer was washed once with water and twice with an aqueous saturated solution of sodium chloride
4. dry with materialdried over anhydrous sodium sulfate
5. distillationThe solvent was distilled off under reduced pressure
6. customthe residue was purified by silica gel column chromatography (n-hexane:ethyl acetate=20:1)