Nitric Acid → 2,6-Difluoro-3-nitrobenzoic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of 31.4 grams (0.498 mole) of 70% nitric acid and 107.1 grams (1.092 moles) of concentrated sulfuric acid was cooled to 10° C. and added dropwise to 75.0 grams (0.474 mole) of stirred 2,6-difluorobenzoic acid. The complete addition required 25 minutes during which time the resultant reaction caused the reaction mixture temperature to rise to 50° C. Upon complete addition the reaction mixture temperature was maintained at 50° C. for one hour, then allowed to cool to ambient temperature where it stirred for 16 hours. The reaction mixture was poured into 250 ml of ice-water and stirred until the ice melted. The mixture was poured into a separatory funnel and extracted with three portions of diethyl ether. The combined extracts were washed with three portions of 400 ml of an aqueous solution saturated with sodium chloride. The organic layer was filtered through phase separation paper and the filtrate concentrated under reduced pressure to a residual solid. The solid was recrystallized from heptane-ethyl acetate to give 19.4 grams of 2,6-difluoro-3-nitrobenzoic acid. The mother liquor was concentrated under reduced pressure to give an additional 56.5 grams of this product.

Provenance & Evidence