Benzoic acid, 4-hydroxy-3-nitro-, methyl ester → Methyl 3-amino-4-hydroxybenzoate

To a 2000 ml three-necked flask containing 3-Nitro-4-hydroxy-benzoic acid methyl ester (43 g, 2188 mmol) in MeOH (860 ml; 20 vols) was added palladium on carbon in water (2 g in 10 ml of water). Ammonium formiate (68.76 g, 5 eq.) was added in a single portion under stirring. After 2 to 3 minutes a suspension was observed, and temperature raised from 20° C. to 30° C. Ice bath was used to cool reaction mixture to 20° C. and the reaction was stirred at 20° C. for 40 minutes until completion (no more yellow color). Reaction mixture was filtered on silica plug, rinsed with MeOH, and the filtrate was concentrated under vacuum to give a green oil which was taken up in ethyl acetate (400 ml). The organic phase was washed twice with water, dried over MgSO4, filtered and concentrated to give a cream solid m=31.35 g (86%).

1. temperaturetemperature raised from 20° C. to 30° C
2. customIce bath was used
3. temperatureto cool
4. customreaction mixture to 20° C.
5. stirringthe reaction was stirred at 20° C. for 40 minutes until completion (no more yellow color)
6. customReaction mixture
7. filtrationwas filtered on silica plug
8. washrinsed with MeOH
9. concentrationthe filtrate was concentrated under vacuum
10. customto give a green oil which
11. washThe organic phase was washed twice with water
12. dry with materialdried over MgSO4
13. filtrationfiltered
14. concentrationconcentrated
15. customto give a cream solid m=31.35 g (86%)

ORD record

ord-8c37a229fd9340f6bc02b32fc4466462

Source dataset

uspto-grants-2010_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07846925B2