Water → 2-Fluoro-5-methoxybenzoic acid

To a vigorously stirred mixture of 4-fluoro-3-methylanisole (12.0 g, 85.6 mmol) and pyridine (41.7 g, 527 mmol) in water (170 mL) at 50° C. was added portion-wise potassium permanganate (44.65 g, mmol) and then maintained at this temperature for 2 h. The resulting mixture was then allowed to cool to RT and allowed to stand overnight and then heated for a further 5 h at 50° C. Then the mixture was filtered over celite and then the residue was washed with sulfuric acid (conc. 100 mL). The combined filtrates were then half-evaporated and neutralised with potasssium carbonate. Then the mixture was washed with diethyl ether and then the aqueous layer was acidified with hydrochloric acid (conc.) and the product extracted with diethyl ether. The combined extracts were then dried over sodium sulphate. After filtration and evaporation the crude solid was recrystallised from 1,2,-dichloroethane to afford the title compound (4.4 g, 30%) as a light pink solid. MS m/e=168.9 (M−H).

1. temperaturemaintained at this temperature for 2 h
2. temperatureheated for a further 5 h at 50° C
3. filtrationThen the mixture was filtered over celite
4. washthe residue was washed with sulfuric acid (conc. 100 mL)
5. customThe combined filtrates were then half-evaporated
6. washThen the mixture was washed with diethyl ether
7. extractionthe product extracted with diethyl ether
8. dry with materialThe combined extracts were then dried over sodium sulphate
9. filtrationAfter filtration and evaporation the crude solid
10. customwas recrystallised from 1,2,-dichloroethane

ORD record

ord-6c292e92f9e04acf94f8f954c465fb21

Source dataset

uspto-grants-2005_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06846832B2