Kinetic applications of electron paramagnetic resonance spectroscopy. XX. 2,4,6-Tri(tert-butyl)benzyl, -anilino, -phenoxy, and -phenylthiyl radicals

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DOIResolve DOI: http://doi.org/10.1021/ja00854a032
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TypeArticle
Journal titleJournal of the American Chemical Society
ISSN0002-7863
Volume97
Issue21
Pages61516154; # of pages: 4
AbstractThe title radicals have been generated, and their kinetic behavior has been examined. The EPR parameters for the benzyl and anilino radicals indicate that the benzylic and amino hydrogens are coplanar with the aromatic rings. The benzyl radical decays rapidly with second-order kinetics (k = (5 ± 2) × 108 M-1 sec-1 at 24°) to give the bibenzyl. The anilino radical exists in equilibrium with the hydrazine (ΔH = -13.1 ± 0.5 kcal/mol, ΔS = -27 ± 2 gibbs/mol). The rate constant for anilino decay to its dimer can be represented by log (k-1/M-1 sec-1) = 6.3(±1.0) - 2.5(±0.8)/θ, where θ = 2.3RT kcal/mol, and that for decomposition of dimer to two anilino radicals by log (k1/sec-1) = 12.2 - 15.6/θ. The phenylthiyl radical is also in equilibrium with its dimer at ambient temperatures (ΔH = -23.3 kcal/mol), but the phenoxy radical shows no sign of dimerization even at -100°. The behavior of these four radicals is discussed in terms of the strengths of the bonds formed by head-to-head dimerization.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC)
Peer reviewedYes
NPARC number21276433
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Record identifier3c63960e-a5fa-4f79-98d1-599ace4d3c53
Record created2015-10-13
Record modified2016-05-09
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