反应详情

A solution of 28 g (112 mmol) of 2-amino-5-nitro-4-trifluoromethyl-benzoic acid in 550 ml of methanol is cooled to 0° C. under nitrogen and concentrated H2SO4 is added dropwise in order to keep the temperature around 20° C. Upon completion of the addition, the mixture is heated to reflux for 24 hours. It is then allowed to cool to room temperature and the mixture is concentrated in vacuo to about 50 ml. This residue is poured onto ice and extracted with ethyl acetate. The organic phase is washed with a saturated aqueous solution of NaHCO3 and brine, dried over Na2SO4, filtered and concentrated in vacuo. The crude product is recrystallized in toluene to give 26.7 g (90%) of 2-amino-5-nitro-4-trifluoromethyl-benzoic acid methyl ester as yellow crystals, m.p. 174-175° C.

1. customthe temperature around 20° C
2. additionUpon completion of the addition
3. temperaturethe mixture is heated
4. temperatureto reflux for 24 hours
5. concentrationthe mixture is concentrated in vacuo to about 50 ml
6. additionThis residue is poured onto ice
7. extractionextracted with ethyl acetate
8. washThe organic phase is washed with a saturated aqueous solution of NaHCO3 and brine
9. dry with materialdried over Na2SO4
10. filtrationfiltered
11. concentrationconcentrated in vacuo
12. customThe crude product is recrystallized in toluene