Negative activation energies and compensation effects for the reactions of diarylanimyl radicals with phenols

Article abstract of DOI:10.1007/BF00713594

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.