Hydrogen Atom Abstraction Reactions by Cyanide Ion‐Radicals

Abstract

Ion‐molecule reactions of low energy (0–0.15 ev) CHN⁺ and CH₃N⁺ are shown conclusively to follow a hydrogen atom abstraction mechanism of the type, XH⁺+YH→XH₂⁺+Y. These reactions are presumably bimolecular being first order with respect to each reactant over the pressure range 10^—7—10^—3 mm Hg. The rates of these reactions are markedly influenced by the molecular structure of both the cyanide ion and the hydrogen donor (YH). Ion‐molecule reactions of this type are similar to the hydrogen atom abstraction processes of free radicals, but differ in having no appreciable temperature coefficients (in the range of 100–215°C), and in having much larger rate constants. On the basis of this study, chemical species having unpaired electrons whether charged (ion‐radicals) or uncharged (free radicals) are shown to undergo similar types of reactions. Possible implications of these observations to the field of radiation chemistry are discussed.