Premium
Newer aspects of electron transfer in electrophilic Aromatic Nitration. Radical pairs as reactive intermediates by time‐resolved spectroscopy
Author(s) -
Bockman T. Michael,
Kochi Jay K.
Publication year - 1994
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610070703
Subject(s) - nitration , chemistry , anisole , photochemistry , electrophile , electrophilic aromatic substitution , electron transfer , toluene , electrophilic substitution , catalysis , organic chemistry
Aromatic nitration is effectively carried out by the deliberate irradiation of the charge‐transfer absorption band ( hv CT ) of the transient electron donor–acceptor complex [ArH, NO 2 Y + ], where NO 2 Y + represents common nitrating agents. Time‐resolved spectroscopy demonstrates that the charge‐transfer nitration effected in this way proceeds via an electron‐transfer mechanism, in which the collapse of the reactive triad, [ArH + · , NO 2 · , Y] is critical to the formation of the Wheland intermediate. Comparative product analyses of toluene and anisole nitrations together with the ‘non‐conventional’ products arising from NO + catalysis, ipso attack and addition/elimination show that the activation process leading to charge‐transfer (photochemical) nitration is indistinguishable from that leading to electrophilic (thermal) aromatic nitration.