- Negative activation energies and compensation effects for the reactions of diarylanimyl radicals with phenols
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The temperature dependence of the rate constants of the reaction of 4,4'-disubstituted diphenylaminyl radicals (ArAr'N.) with phenols has been studied by a laser pulse photolysis technique.The linear relationships between activation energies E1 (negative in the majority of cases) and logarithms of pre-exponential factors logA1 have been established.These results coincide with the two-parametric correlations of logk1 with ?+ constants of substituents in phenol and aminyl radicals under isothermal conditions.The reaction rate constants decrease considerably when toluene is used instead of n-decane. - Key words: aminyl radicals, phenols, negative temperature coefficient, isoparametric correlations.
- Varlamov, V. T.,Denisov, N. N.,Nadtochenko, V. A.
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- KINETICS AND MECHANISM OF THE THERMAL DISSOCIATION OF O,O'-BIS(1,3,5-TRI-tert-BUTYL-4-OXO-2,5-CYCLOHEXADIENYL)-p-BENZOQUINONE DIOXIME IN SOLUTION
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The kinetics and mechanism of the thermal dissociation of O,O'-bis(1,3,5-tri-tert-butyl-4-oxo-2,5-cyclohexadienyl)-p-benzoquinone dioxime (quinol ether) in solutions in nonpolar solvents were investigated.The dissociation of the quinol ether is a reversible two-stage process and involves the formation of an intermediate radical.In relation to the reaction conditions (initial concentration, temperature) the dissociation rate of the quinol ether obeys the kinetic equations ω = keff.c1/2 or ω = k1c.The change in the reaction order is due to the ratio of the rates of dissociation of the intermediate radical and of its reaction with the phenoxyl radical.
- Khizhnyi, V. A.,Danilova, T. A.,Goloverda, G. Z.,Dobronravova, Z. A.
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p. 776 - 781
(2007/10/02)
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