Formation and photolysis of alkyl and peroxy radicals in dilute glass matrices

Abstract

The use of molecular oxygen as a spin trap in rigid glassy hydrocarbon media at 77 K is investigated. By slight warming of the matrix, oxygen is found to effectively scavenge the isolated alkyl radicals produced by γ-irradiation to give RO2•, but does not react with radical pairs lying in the ionization tracks. The yield of scavengable radicals in 3MP is determined and compared to the findings of other workers. The butyl radical yields for γ-irradiated 1.0 mol l−1 butyl chlorides in 3MP are found to be: t-BuCl, 5.8; i-BuCl, 5.1; 2-BuCl, 4.9; and 1-BuCl, 2.2. Alkyl radicals cannot be recovered from either RO2 or BuO2 by uv photolysis due to solvent abstraction reactions, or because of photon induced reactions of the alkyl radicals. Photolysis of the butyl radicals themselves at 253.7 nm give rise to decomposition and solvent abstraction reactions.

Photochemical Reactions of Free Radicals in the Solid Phase

“…The formation of 3-methylpentyl radicals when alkyl radicals, obtained on y-irradiation of 1 M solutions of alkyl chlorides in 3-MP, are exposed to radiation with A = 253.7 nm at 77 K, was observed also in another study 62 . The fact that t-butyl radicals are partly converted into isobutyl radicals in solutions of t-butyl chloride in 3-MP is apparently associated with the high concentration of the solutions and the possibility of reactions involving associated species.…”