Matviyenko Y. Kinetics, substrate selectivity and mechanisms of oxidation of alkanes by peroxynitrous acid

The thesis is devoted to the study of the kinetics, selectivity and KIE interaction of hydrocarbons with peroxynitrous acid (HOONO) in aqueous solutions and gas phase to establish the mechanisms of these reactions. A striking similarity of substrate selectivities in a wide range of alkanes, KIE and their temperature dependences for the reactions of hydrocarbons with HOONO acid and OH-radicals in aqueous solutions as well as in gas has been found. For the first time a KIE anomaly was observed: the quantities kН/kD increase with temperature in the reactions of cyclohexane and cyclohexane-d12 with peroxynitrous acid and hydroxyl radicals in water. Low values of relative rate constants for the reactions of cyclohexane and cyclopentane in water and their reverse temperature dependence compared with gas-phase reactions has also been found. These anomalies are explained by the solvent cage effect model at the meeting stage of reactants. The data obtained in this work permit to conclude unequivocally that the active particles in the reactions of RH + HOONO in both phases are OH radicals formed during the homolysis of the HO-ONO bond.