Kinetics of bimolecular decay of α‐tocopheroxyl free radicals studied by ESR

Abstract

The kinetics of bimolecular decay of α-tocopheroxyl free radicals (T^.) was studied by ESR mainly in ethanol and heptanol solvents. A second-order kinetic law was observed during the whole course of reaction (-d[T^.]d t = 2 k[T^.]²) and the following rate constants were determined with good accuracy in the temperature range 281–321 K: ethanol: log(2 k) = 8.2 ± 0.5 — (6.6±0.7 kcal/mol)/(2.3 RT) M⁻¹·s⁻¹; heptanol: log(2 k)=6.1±0.4-(4.3±0.6 kcal/mol)/(2.3 RT) M⁻¹.s⁻¹. The global rate constant clearly increases with solvent polarity.