title: Electrophilic aromatic nitration: understanding its mechanism and substituent effects.
abstract: Theoretical calculations and gas-phase mass spectrometric studies were performed for the reaction of the naked (NO2+) and monosolvated (CH3NO2.NO2+) nitronium ion with several monosubstituted aromatic compounds. From these studies, we propose a general model for regioselectivity based on the single-electron transfer (SET) mechanism and an alternative mechanistic scheme for electrophilic aromatic nitration. This scheme considers the SET and the polar (Ingold-Hughes) mechanisms as extremes in a continuum pathway, the occurrence and extents of both mechanisms being governed mainly by the ability, or lack of ability, of the aromatic compound to transfer an electron to NO2+.
authors.affiliation: Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, s/n, 24020-150, Niterói-RJ, Brazil.
authors.forename: Jorge Freire
authors.initials: JF
authors.lastname: de Queiroz
authors.forename: José Walkimar de M
authors.initials: JW
authors.lastname: Carneiro
authors.forename: Adão A
authors.initials: AA
authors.lastname: Sabino
authors.forename: Regina
authors.initials: R
authors.lastname: Sparrapan
authors.forename: Marcos N
authors.initials: MN
authors.lastname: Eberlin
authors.forename: Pierre M
authors.initials: PM
authors.lastname: Esteves