反应详情

温度

0 °C

Under an inert atmosphere of nitrogen 1-(2,3-difluoro-phenyl)-ethanone (5.0 g (32 mmol) was added dropwise to sulphuric acid (95-97%, 20 ml), cooled to 0° C., at such a rate that the temperature was maintained below 5° C. Thereafter, the reaction mixture was cooled to −15° C. and a solution of nitric acid (3.22 ml, 46.4 mmol) in sulphuric acid (95-97%, 4.6 ml) was added dropwise at −15° C. After stirring at −10° C. for 45 minutes, the mixture was poured on ice. Ethyl acetate was added, then the organic layer separated, washed with water, dried over sodium sulphate, and evaporated at reduced pressure. Purification of the crude light yellow oil (5.64 g) by chromatography on silica gel using a gradient of heptane/ethyl acetate=100:0 to 0:100 yielded the 1-(2,3-difluoro-5-nitro-phenyl)-ethanone (1.83 g, 28% of theory) as a light yellow oil together with a mixture of 1-(2,3-difluoro-5-nitro-phenyl)-ethanone and 1-(2,3-difluoro-6-nitro-phenyl)-ethanone.

1. temperatureat such a rate that the temperature was maintained below 5° C
2. temperatureThereafter, the reaction mixture was cooled to −15° C.
3. additionthe mixture was poured on ice
4. customthe organic layer separated
5. washwashed with water
6. dry with materialdried over sodium sulphate
7. customevaporated at reduced pressure
8. customPurification of the crude light yellow oil (5.64 g) by chromatography on silica gel using a gradient of heptane/ethyl acetate=100:0 to 0:100