Pulse radiolysis : adducts of vinyl compounds and simple free radicals

Abstract

Pulse radiolysis of (a) aqueous de-aerated solutions of acrylamide, methacrylamide, N-t-butyl acrylamide, acrylic acid and acrylonitrile and (b) styrene and α-methyl styrene in de-aerated cyclohexane, dioxane, tetrahydrofuran and benzene results in intense transient absorption spectra. Those for system (a) are assigned to monomer radical anions, m^–₁˙, and the products of reaction of a radical with the monomer. Their decay is second order and values of the extinction coefficients and bimolecular rate constants have been determined. Absolute rate constants( M^–1 sec^–1) were obtained for the reaction of acrylamide with (a) hydrated electrons, (2.1 ± 0.4)× 10¹⁰, (b) OH radicals, (2.0 ± 0.5)× 10⁹ and for the reaction of the product of the reaction of the radical and monomer with oxygen and ferricyanide ion, (1.9 ± 0.3 )× 10⁹ and (6.8 ± 0.4)× 10⁶ respectively. For system (b) the absorptions and decay kinetics observed are not completely understood. At least two distinct species are formed, one of which can be ascribed to a radical but neither to a radical anion.