Electrophilic aromatic substitution. Part 37. Products of aromatic nitrations of some chloronitrobenzenes and substituted benzoic acids in solutions of dinitrogen pentaoxide and of nitronium salts in nitric acid
Yields of aromatic products of nitration in nitric acid solutions containing dinitrogen pentaoxide or nitronium salt have been determined. Evidence for the intrusion of a mechanism other than the normal nitronium ion one comes from comparison of products in the two media and from the observation of 15N NMR CIDNP effects. The additional mechanism operative with some substrates in concentrated solutions of dinitrogen pentaoxide is postulated to be one in which reversible addition of the NO3 radical is followed by combination with NO2. Dienes produced in this way can give aromatic nitroproducts by elimination of nitric acid. Nitrodecarboxylation of substituted benzoic acids occurs by a radical process.