反应详情

温度

-10 °C

20.0 g (114.9 mmol) of 2,2,2-trifluoroacetophenone were initially charged in 80 ml of conc. sulphuric acid, and the mixture was cooled to −10° C. A solution, prepared beforehand at −10° C., of 4.8 ml (114.8 mmol) of nitric acid in 20 ml of conc. sulphuric acid was added dropwise to this mixture such that the reaction temperature did not exceed −5° C. After the addition had ended, the reaction mixture was stirred between −10° C. and 0° C. for 1 h and then added carefully to ice-water. By addition of 50% strength aqueous sodium hydroxide solution, the pH of the mixture was adjusted to about 9-10. The mixture was extracted three times with ethyl acetate, and the combined organic phases were dried over magnesium sulphate and concentrated under reduced pressure. The residue was purified by chromatography on silica gel (mobile phase initially cyclohexane/dichloromethane 2:1 to 1:1, finally pure dichloromethane). This gave 19.2 g of the target product (76.2% of theory).

1. customA solution, prepared
2. additionwas added dropwise to this mixture such that the reaction temperature
3. customdid not exceed −5° C
4. additionAfter the addition
5. extractionThe mixture was extracted three times with ethyl acetate
6. dry with materialthe combined organic phases were dried over magnesium sulphate
7. concentrationconcentrated under reduced pressure
8. customThe residue was purified by chromatography on silica gel (mobile phase initially cyclohexane/dichloromethane 2:1 to 1:1, finally pure dichloromethane)