反应详情

A solution of 65.0 g (300 mmol) of N-(2-methyl-5-trifluoromethyl-phenyl)-acetamide in 520 ml of concentrated H2SO4 is treated dropwise with a solution of 152.5 g (1.5 mol) of potassium nitrate in 520 ml of concentrated H2SO4 under N2 and the mixture is kept at room temperature with an ice-bath. The mixture is then stirred for another 2 hours at room temperature and then poured onto ice. The suspension is filtered and the filter cake is dissolved in ethyl acetate, dried over anhydrous Na2SO4, filtered and concentrated in vacuo. Crude product is purified by flash chromatography (SiO2, hexane/ethyl acetate 1:1) to furnish the nitration product as a mixture of regioisomers (62.44 g, 238 mmol). 51.0 g (195 mmol) of this crude product are dissolved in 1000 ml water and heated to 100° C. and treated portionwise with a mixture of 184 g (1167 mmol) of potassium permanganate and 70.4 g (585 mmol) of magnesium sulfate monohydrate. The mixture is kept at 100° C. for another 2 hours and then allowed to cool to room temperature. The mixture is then filtered and the filtrated is extracted with ethyl acetate. The organic phase is dried over anhydrous Na2SO4, filtered and concentrated in vacuo to give 19.3 g (27% over 2 steps) of 2-acetylamino-5-nitro-4-trifluoromethyl-benzoic acid as yellow crystals. 1H-NMR (DMSO-d6, 400 MHz) 9.13 (s, 1H), 8.67 (s, 1H), 1.98 (s, 3H).

1. customthe mixture is kept at room temperature with an ice-bath
2. additionpoured onto ice
3. filtrationThe suspension is filtered
4. dissolutionthe filter cake is dissolved in ethyl acetate
5. dry with materialdried over anhydrous Na2SO4
6. filtrationfiltered
7. concentrationconcentrated in vacuo
8. customCrude product is purified by flash chromatography (SiO2, hexane/ethyl acetate 1:1)
9. customto furnish the nitration product
10. additionas a mixture of regioisomers (62.44 g, 238 mmol)
11. temperatureheated to 100° C.
12. waitThe mixture is kept at 100° C. for another 2 hours
13. temperatureto cool to room temperature
14. filtrationThe mixture is then filtered
15. extractionthe filtrated is extracted with ethyl acetate
16. dry with materialThe organic phase is dried over anhydrous Na2SO4
17. filtrationfiltered
18. concentrationconcentrated in vacuo