Oxidation of perfluoroaromatics

Abstract

3,4,5,6-Tetrafluoro-2-nitroaniline (I), 2,3,5,6-tetrafluoro-4-nitroaniline (IV) and 2,5,6-trifluoro-4-nitro-1,3-phenylenediamine (VI) react with nitrous acid to give 3,4,5-trifluoro-6-nitro-1,2-diazo-oxide (III), 3,5,6-trifluoro-4-nitro-1,2-diazo-oxide and (V) 5-fluoro-6-nitro-bis-1,2:3,4-diazo-oxide (VII), respectively. Reduction of the diazo-oxide (III) with hypophosphorous acid gives 4,5,6-trifluoro-3-nitrophenol (VIII). Treatment of 2,3,4,6-tetrafluoroacetanilide with nitric acid affords trifluoro- p-benzoquinone (X), the reduction of which gives trifluorohydroquinone (XI). Proton and fluorine chemical shifts and coupling constants of the new compounds are reported.