反应详情

2,3,6-Trifluorobenzoic acid (21.0 g) is added to conc. sulfuric acid (120 ml) under ice-cooling. To the mixture is added dropwise a solution of potassium nitrate (14.5 g) in conc sulfuric acid (30 ml) at below 20° C. After the addition, the mixture is stirred at room temperature for one hour. The reaction mixture is poured into ice water and extracted with diethyl ether. The extract is dried over magnesium sulfate, and then the solvent is distilled off. The residue is recrystallized from dichloromethane-n-hexane to give 2,5,6-trifluoro-3-nitrobenzoic acid (22 g), as colorless prisms, m.p. 98°-99° C.

1. temperaturecooling
2. additionAfter the addition
3. extractionextracted with diethyl ether
4. dry with materialThe extract is dried over magnesium sulfate
5. distillationthe solvent is distilled off
6. customThe residue is recrystallized from dichloromethane-n-hexane