Ultraviolet absorption spectra of the 2-Phenylethyl radical formed during pulse radiolysis

Abstract

2-Phenylethyl radicals (Ph-CH₂-·CH₂) were prepared by the decarboxylation reaction of 3-phenylpropanoic acid with sulfate radical ions (SO₄^-·) formed during the pulse radiolysis of aqueous solutions containing peroxydisulfate (S₂O₈^2-) ions. The ultraviolet absorption spectrum of the transient radicals consisted of a band centred at 309nm with an extinction coefficient of 5000 1, mol^-1 cm^-1. Attempts were made to form phenylethyl radicals by the electron-attachment dissociation reaction of (2-haloethy1)benzenes. Contrary to literature reports, it was found that the latter reaction does not occur in either cyclohexane, benzene or aqueous solutions of (2-chloroethyl)- and (2-bromoethyl)-benzenes.