Reactions of alkoxy and peroxy radicals with carbon monoxide

Abstract

Experimental rate constants of the reactions HO· + CO → H· + CO2, RO· + CO → R· + CO2, HO2· + CO → HO· + CO2, and RO2· + CO → RO· + CO2 are analyzed in the framework of the intersecting-parabolas model. The transition states of the additions of the methoxy and methylperoxy radicals to carbon monoxide were calculated by quantum-chemical methods. The reactions occur in two consecutive steps: first the HO· (RO·, RO2·) radical adds to CO and then the resulting unstable intermediate radical decomposes to evolve CO2. The kinetic parameters of these reactions are calculated by two methods (using the intersecting-parabolas model and the quantum-chemical method). The activation energies and rate constants of a series of RiO· + CO and RiO2· + CO reactions are calculated. A comparison of the kinetic parameters suggests close similarity between the transition states in the additions of the O-centered radicals to CO and olefins.