Electrophilic aromatic substitution. Part 17. Products, kinetics, and mechanism of nitration in trifluoroacetic acid

Abstract

Benzene, chlorobenzene, toluene, and the di- and tri-methylbenzenes are mononitrated quantitatively at a rate convenient for kinetic study at 25 °C in trifluoroacetic acid containing nitric acid and up to 1 mol dm^–3 of water. Product yields suggest that the consequence of ipso-attack of nitronium ion is migration of the nitro-group to an unsubstituted position. The formation of the nitryl cation can be rate-limiting. When it is not, rate limitation by a step which is insensitive to the nature of sufficiently reactive aromatic compounds is observed. The level of reactivity at which this limiting rate is observed is compared with that found in seven other media.