Isopropanol → 2-Amino-4-fluorophenol

In a 500-ml flask, place 39.3 g (0.25 m) of 4-fluoro-2-nitrophenol (2a) and 120 ml of isopropyl alcohol and warm to 40° C. Add 1.5 g of 5% Pd/C wet with 1.5 ml of water and stir the mixture vigorously. Add a solution of 84.1 g (1.0 m) of potassium formate in 85 ml of water in drop wise over an hour keeping the temperature at 45°-53° C. Stir the mixture at 50° C. for 2.5 hrs. Add 150 ml of propyl acetate and 100 ml of water and stir for a few min. Filter off catalyst and wash with 100 ml of propyl acetate and 100 ml of water. Separate propyl acetate solution, and wash with 150 ml water and 150 ml of brine containing 1-2 g sodium hydrosulfite. Dry propyl acetate solution over magnesium sulfate and concentrate to approximately 75 ml. Add 300 ml of heptane slowly with gentle stirring. Concentrate under a reduced pressure till most of propyl acetate evaporated. Add 150 ml of heptane to resulting mush and cool in an ice bath for about an hour. Collect solid, wash with heptane, and dry in a vacuum oven to give 29.0 g (91%) of 2-amino-4-fluorophenol (3a; X=F) as gray solids.

1. customat 45°-53° C
2. stirringStir the mixture at 50° C. for 2.5 hrs
3. stirringstir for a few min
4. filtrationFilter off catalyst
5. washwash with 100 ml of propyl acetate and 100 ml of water
6. washSeparate propyl acetate solution, and wash with 150 ml water and 150 ml of brine containing 1-2 g sodium hydrosulfite
7. concentrationDry propyl acetate solution over magnesium sulfate and concentrate to approximately 75 ml
8. additionAdd 300 ml of heptane slowly with gentle stirring
9. concentrationConcentrate under a reduced pressure till most of propyl acetate
10. customevaporated
11. additionAdd 150 ml of heptane
12. customto resulting mush
13. temperaturecool in an ice bath for about an hour
14. customCollect solid
15. washwash with heptane
16. customdry in a vacuum oven

ORD-Eintrag

ord-6b14a3d63e7046aaa4fa1c6fc2a3d9dd

Quelldatensatz

uspto-grants-2002_11

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06482985B1