Sulfuric Acid → 7-Chloro-6-fluoro-1-(2,4-difluoro-5-nitrophenyl)-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid

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Reaction Steps

To 25 ml of conc. sulfuric acid was added 6.0 grams of 7-chloro-1-(2,4-difluorophenyl)-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid. With ice cooling and stirring, to the solution was added 5.0 g of potassium nitrate in portions. The temperature was slowly elevated to 80° C. at which stirring was continued for 2 hours. The reaction solution was allowed to cool, poured into 200 g of ice water, and allowed to stand overnight. The precipitate was collected by filtration, washed with distilled water, ethanol and diisopropyl ether, and air dried, to give 6.4 g of the title compound.

Provenance & Evidence