Hydrochloric Acid → 2-Amino-4,6-difluorobenzoic acid

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Reaction Conditions

Reaction Steps

Hydrogen peroxide (35% solution in water, 23 ml) was added dropwise to a stirred solution of 4,6-difluoro-2,3-dioxoindoline (14 g) in a concentrated aqueous sodium hydroxide solution (33%, 115 ml) that was heated to 70° C. The mixture was heated to 70° C. for 15 minutes. The resultant mixture was cooled to 0° C. and the the mixture was acidified to pH4 by the addition of concentrated aqueous hydrochloric acid. The mixture was extracted with ethyl acetate. The organic layer was separated, washed with brine, dried over magnesium sulphate and evaporated to give 2-amino-4,6-difluorobenzoic acid (12 g); NMR Spectrum: (DMSOd6) 6.25 (m, 1H), 6.38 (m, 1H).

Provenance & Evidence