Phosgene → 2H-3,1-Benzoxazine-2,4(1H)-dione, 5-nitro-

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Reaction Steps

A solution of 56.5 g of 2-amino-6-nitrobenzoic acid hydrochloride in 200 ml of demineralized water and 200 ml of tetrahydrofuran is cooled to 10° while stirring and treated with phosgene at 10°-30° for 1 hour, a precipitate resulting. The mixture is subsequently diluted with 300 ml of demineralized water and air is conducted through the suspension vigorously for about 3 hours (until the sample is negative for phosgene). The precipitate is filtered off, washed with water and dried in vacuo over phosphorus pentoxide. There is obtained 6-nitroisatoic acid anhydride as beige crystals of m.p. 220°-222° (decomposition).

Provenance & Evidence