Hydrogen Peroxide → 2-Amino-6-bromobenzoic acid

Temperature

80 °C

To 4-bromoindoline-2,3-dione (8.94 g, 39.6 mmol) was added 1.0 M sodium hydroxide (40 mL, 120 mmol) to give a dark brown mixture. The mixture was heated to 80° C. then 20% hydrogen peroxide (9 mL, 88 mmol) was added slowly over 15 min (caution: a strong exotherm was observed upon reagent addition). The mixture was then stirred at 80° C. for 1 h. After this time, the mixture was cooled in an ice bath to ˜10° C. and then concentrated to a residue. HCl was added cautiously to the residue until the pH of the mixture was 4-5. Once at the prescribed pH, the mixture was then concentrated to dryness and MeOH (150 ml) was added. The resulting suspension stirred for 15 min and then filtered. The filtrate was concentrated to dryness and dried under vacuum for 14 h to yield 2-amino-6-bromobenzoic acid (9.18 g) as a brown solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 6.72 (1H, t, J=7.91 Hz), 6.60 (1H, dd, J=7.78, 1.00 Hz), 6.52 (1H, dd, J=7.91, 1.13 Hz). LCMS Method D: retention time 0.68 min, [M+1] 200.0.

1. customto give a dark brown mixture
2. additiona strong exotherm was observed upon reagent addition)
3. temperatureAfter this time, the mixture was cooled in an ice bath to ˜10° C.
4. concentrationconcentrated to a residue
5. additionHCl was added cautiously to the residue until the pH of the mixture
6. concentrationOnce at the prescribed pH, the mixture was then concentrated to dryness and MeOH (150 ml)
7. additionwas added
8. stirringThe resulting suspension stirred for 15 min
9. filtrationfiltered
10. concentrationThe filtrate was concentrated to dryness
11. customdried under vacuum for 14 h

ORD record

ord-597f038de8e647c7806973fbfef947fd

Source dataset

uspto-grants-2013_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08575184B2