- N,N-di(4-halophenyl)nitrenium ions: Nucleophilic trapping, aromatic substitution, and hydrogen atom transfer
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(Figure Presented) The reactive intermediates N,N-di(4-chlorophenyl) nitrenium ion and N,N-di(4-bromophenyl)nitrenium ion were generated through photolysis of the corresponding N-amino(2,4,6,-collidinium) ions. The behavior of these diarylnitrenium ions was characterized by laser flash photolysis, analysis of the stable photoproducts, and ab initio calculations with density functional theory. The latter predict these species to have singlet ground states. The halogenated diarylnitrenium ions are significantly longer lived than the unsubstituted diphenylnitrenium ion. Specifically, cyclization to form carbazole derivatives occurs negligibly, if at all, with the halogenated derivatives. They do, however, carry out most of the characteristic reactions of singlet arylnitrenium ions, including combining with nucleophiles on the aryl rings, adding to arenes, and accepting electrons from readily oxidized traps. Interestingly these species also abstract H atoms from 1,4-cyclohexadiene and various phenol derivatives. The implication of the latter process in relation to the computed singlet-triplet energy gaps of ca. -12.5 kcal/mol is discussed.
- Thomas, Selina I.,Falvey, Daniel E.
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p. 4626 - 4634
(2008/02/07)
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- KINETICS OF THE REACTION OF THE 2,4,6-TRI-TERT-BUTYLPHENOXYL RADICAL WITH AROMATIC AMINES UNDER QUASIEQUILIBRIUM CONDITIONS, AND THE DISSOCIATION ENERGY OF THE N-H BOND IN AROMATIC AMINES
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We have studied the kinetics of the reaction of the 2,4,6-tri-tert butylphenoxyl radical with 11 aromatic amines under quasiequilibrium conditions.The equilibrium constant for each amine was determined from the kinetic results.These values, together with their temperature dependence, were used to calculate the dissociation energy of the N-H bond in the 11 aromatic amines.By using earlier results for the reaction of the aroxyl radical with cumyl hydroperoxide, catalyzed by aromatic amines, we have calculated the rate constants for the reaction of 10 aminyl radicals with cumyl hydroperoxide and of cumylperoxy radicals with 10 aromatic amines.
- Varlamov, V. T.,Denisov, E. T.
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p. 657 - 662
(2007/10/02)
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