2-Methyl-3-nitrobenzoic acid → 3-Hydroxy-2-methylbenzoic Acid

Temperature

40 °C

3-Nitro-2-methyl benzoic acid (90.5 g, 0.500 mol) was dissolved in 1.0 mol/L aqueous solution (500 ml) of sodium hydroxide. 10% Palladium-carbon (4.5 g) was added and the mixture was stirred under a hydrogen atmosphere (2-3 atm) for 9 hours at 40° C. The catalyst was filtered off and conc. sulfuric acid (94.0 ml) was added under ice-cooling. An aqueous solution of sodium nitrite (35.0 g, 0.500 mol/150 ml) was added over one hour while stirring the mixture at riot more than 6° C., and after the dropwise addition, the mixture was heated at 65° C. for 1.5 hours. The inner temperature rose to 57° C. in an hour. The reaction mixture was cooled to room temperature, and saturated brine (300 ml) was added. The mixture was extracted with ethyl acetate (700 ml). The organic layer was washed with saturated brine (200 ml) and dried over magnesium sulfate. The solvent was distilled away to give 3-hydroxy-2-methyl benzoic acid as a pale brown solid.

1. filtrationThe catalyst was filtered off
2. additionconc. sulfuric acid (94.0 ml) was added under ice-
3. temperaturecooling
4. stirringwhile stirring the mixture at riot more than 6° C.
5. additionafter the dropwise addition
6. temperaturethe mixture was heated at 65° C. for 1.5 hours
7. waitThe inner temperature rose to 57° C. in an hour
8. temperatureThe reaction mixture was cooled to room temperature
9. extractionThe mixture was extracted with ethyl acetate (700 ml)
10. washThe organic layer was washed with saturated brine (200 ml)
11. dry with materialdried over magnesium sulfate
12. distillationThe solvent was distilled away

ORD record

ord-151c97eb709142f3b5da62beabef8d0c

Source dataset

uspto-grants-2000_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06133461