反应详情

A solution of 4-benzoyl-3-hydroxy-5-nitrobenzoic acid, monohydrate prepared as described in Example 1, step A, (100 g) in dry ethanol (2 liter) is evaporated in vacuo in order to remove the water of crystallization. The residue is redissolved in dry ethanol (2 liter), conc. sulfuric acid (45 ml) is added and the solution is refluxed for 20 hours. The excess of ethanol is removed in vacuo, and the residue is triturated with a saturated sodium hyrogen carbonate solution (about 900 ml). The resulting material is collected by filtration and washed with water. After drying and recrystallization from aqueous ethanol, ethyl 4-benzoyl-3-hydroxy-5-nitrobenzoate is obtained with a melting point of 167°-168° C.

1. customis evaporated in vacuo in order
2. customto remove
3. customthe water of crystallization
4. dissolutionThe residue is redissolved in dry ethanol (2 liter)
5. additionconc. sulfuric acid (45 ml) is added
6. temperaturethe solution is refluxed for 20 hours
7. customThe excess of ethanol is removed in vacuo
8. customthe residue is triturated with a saturated sodium hyrogen carbonate solution (about 900 ml)
9. filtrationThe resulting material is collected by filtration
10. washwashed with water
11. customAfter drying
12. customrecrystallization from aqueous ethanol