Comparison of the nitration of polyfluoronitrobenzenes by nitronium salts in superacidic and aprotic media: activation of the nitronium ion by protosolvation.

The reactivity of nitronium tetrafluoroborate in the nitration of deactivated di- and trifluoronitrobenzenes is enhanced in superacidic trifluoromethanesulfonic (triflic) acid compared with aprotic methylene chloride and sulfolane solutions. The enhanced reactivity is discussed in terms of better solubility and higher dissociation of the nitronium salts, as well as protosolvation of NO2+ by superacids.