Generation of radical-cations from naphthalene and some derivatives, both by photoionization and reaction with SO4–˙: formation and reactions studied by laser flash photolysis

Abstract

Radical-cations from naphthalene and some derivatives have been generated in aqueous acetonitrile both by direct photolysis (with λ 248 nm light via biphotonic ionization) and via reaction with SO₄^–˙. The radical-cation reacts rapidly with the parent substrate (k ca. 10⁸ dm³ mol^–1 s^–1) and with nucleophiles (e.g. with N₃^–k= 4.2 × 10⁹ dm³ mol^–1 s^–1 or with water, k 4 × 10⁴ s^–1). The radical-cation from 1-naphthylethanoic acid undergoes rapid decarboxylation (k 5 × 10⁵ s^–1). The radical cations from 4-methyl- and 4-methoxy-phenylethanoic acid also rapidly decarboxylate to yield the corresponding benzyl radicals.