Hydrogen Bromide → 4-Bromo-2-hydroxybenzoic acid

Temperature

5 °C

In water (22.5 ml) and a 47% aqueous solution of hydrobromic acid (22.5 ml), 4-amino-2-hydroxybenzoic acid (5.04 g) was dissolved. While the resulting solution mixture was maintained at 5° C. or lower, an aqueous solution (water: 15.0 ml) of sodium nitrite (2.26 g) was added dropwise thereto, followed by stirring for 30 minutes under ice cooling. The reaction mixture was added, in portions, to a solution of cuprous bromide (5.63 g) dissolved in a 47% aqueous solution of hydrobromic acid (15 ml) under ice cooling. The resulting mixture was stirred at room temperature for 150 minutes. Ethyl acetate was added to the reaction mixture for extraction. The organic layer so obtained was washed with water and then dried over anhydrous sodium sulfate. The residue obtained by distilling off the solvent under reduced pressure was purified by chromatography on a silica gel column (dichloromethane˜10% methanol-dichloromethane), whereby 4-bromo-2-hydroxybenzoic acid (5.51 g) was obtained as a crudely purified product.

1. stirringThe resulting mixture was stirred at room temperature for 150 minutes
2. customThe organic layer so obtained
3. washwas washed with water
4. dry with materialdried over anhydrous sodium sulfate
5. customThe residue obtained
6. distillationby distilling off the solvent under reduced pressure
7. customwas purified by chromatography on a silica gel column (dichloromethane˜10% methanol-dichloromethane)

ORD record

ord-e625e6349f5a4ea38855065a1a016440

Source dataset

uspto-grants-2003_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06525042B1