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Substrate selectivity and mechanism of oxidation of alkanes by peroxynitrous acid in aqueous solution

“…Difficulties in the study of these reactions are due to the instability of PA in neutral and acidic media and the large number of transformation paths [1]. Earlier we found that alkanes, alkenes, and arenes are oxidized by aqueous solutions of PA [9] and by solutions of H 2 O 2 -HNO 2 in an acetate buffer [10,11] and in the phosphate system (H 3 PO 4 -KH 2 PO 4 ) [12,13], in which HOONO is 0040-5760/06/4205-0303 …”

“…(1). The kinetic data for the H 2 O 2 -HNO 2 /acetate buffer system were explained quantitatively [10,11] on the assumption of rapid equilibrium distribution of the PA and the substrate between the gas and the solution, isomerization of the PA to HNO 3 , the formation of OH radicals, and their reaction with the hydrocarbon in the gas (g) and the solution (l). It was found that in this system the alkanes and alkenes react predominantly with the PA in the gas phase (the contribution from the liquid-phase path to the overall rate of decrease of the substrate amounts to 5-15%), whereas the rates of the gas-phase and liquid-phase reactions are commensurable.…”

“…It was found that in this system the alkanes and alkenes react predominantly with the PA in the gas phase (the contribution from the liquid-phase path to the overall rate of decrease of the substrate amounts to 5-15%), whereas the rates of the gas-phase and liquid-phase reactions are commensurable. The small contribution from the liquid-phase reaction (k l RH ) to the overall rate of decrease of the alkanes and alkenes was explained [10,11] by their extremely low solubility in water and by the fact that the main path for destruction of the OH radicals under the investigated conditions is their reaction with the components of the acetate buffer. The aim of the present work was to measure directly the relative liquid-phase rate constants for the reactions of alkanes with PA by the syringe reactor method [14] (in the absence of the gas phase) and to establish the nature of the active particle.…”