The reactions of O(3P) with acetonitrile and propionitrile

Abstract

The reactions of O(3P) with acetonitrile and propionitrile have been studied kinetically in the gas phase as a function of temperature and nitrile concentration. The rate constants obtained experimentally for the consumption of O(3P) in these reactions, in the units L mol−1 s−1, obey the following relations: O + acetonitrile: In k = 20.98 ± 0.23 − 2100 ± 200/T; and O + propionitrile: In k = 21.01 ± 0.19 − 1900 ± 200/T. Mechanisms are discussed in which the reaction is initiated by hydrogen atom abstraction and in which initiation is by addition of O(3P) to the nitrile, followed by decomposition of the addition complex. The kinetic and analytical results are best explained by the mechanism in which the reactions are initiated by RCN + O → R + OCN. In the case of the reaction with acetonitrile, the absolute rate constant is smaller than the experimental value by a factor of 7 ± 20%, independent of temperature, as a result of secondary reactions. Keywords: kinetics, reactions of O(3P) with nitriles.