Electrophilic aromatic nitration: understanding its mechanism and substituent effects.
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+.
de Queiroz
Jorge Freire
JF
Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, s/n, 24020-150, Niterói-RJ, Brazil.
Carneiro
José Walkimar de M
JW
Sabino
Adão A
AA
Sparrapan
Regina
R
Eberlin
Marcos N
MN
Esteves
Pierre M
PM