Homolytic reactions of aromatic side-chains. Part IV. Relative rates of α-hydrogen abstraction by methyl radicals

Abstract

The relative rates (k_rel, toluene = 1) of abstraction of α-hydrogen atoms from alkyl side-chains attached to aromatic nuclei are reported for methyl radicals formed by the photolysis of methylmercuric iodide. The measurements were made by the competitive technique. The results obtained with alkylbenzenes show that the reactivity of α-hydrogen atoms increases in the order: primary < secondary < tertiary. Polar influences exerted by nuclear substituents appear to have no influence on the rate of α-hydrogen abstraction by methyl radicals, since the values of k_rel for p-halogenotoluenes are close to unity.