Reactions of the hydrogen atom with azide, bromide and iodide ions in aqueous solution

Abstract

The reactions of H atoms in aqueous solutions with the halides, bromide and iodide and the pseudo-halide, azide, have been investigated. H atoms were conveniently generated in situ using γ-radiolysis. In no case was molecular hydrogen formed as a result of H atoms reacting with these ions. Major products in the azide system are nitrogen and ammonia, a reaction scheme consistent with both our results from product studies under a variety of conditions and reported pulse radiolysis data is proposed. Deuterated propan-2-ol, which reacts with H atoms to form HD, was used to compete with bromide or iodide ions for reaction with H atoms. The dependence of the HD yield on the relative concentrations of halide and propanol was that expected for simple competition. However, our values for the rate constants k(H+Br -) and k(H+I -) of ⩽2×10 4 and 1×10 6 M -1 s -1, respectively, are considerably smaller than those currently given in the literature.