反应详情

A solution of 2.6 g of 4-hydroxy-3-methoxy-5-nitrobenzoic acid in 26 ml of constant-boiling hydrobromic acid is heated under reflux for 2 hours. After cooling the solvent is distilled in a water-jet vacuum. The crystalline residue is recrystallized from 50 ml of water at boiling temperature. There is obtained 3,4-dihydroxy-5-nitrobenzoic acid in the form of yellow crystals of m.p. 224°-226°.

1. temperatureunder reflux for 2 hours
2. temperatureAfter cooling the solvent
3. distillationis distilled in a water-jet vacuum
4. customThe crystalline residue is recrystallized from 50 ml of water