The electron spin resonance spectra of alkyl aryl ether radical cations

Abstract

Radical cations of alkyl aryl ethers may be generated in a flow system by means of oxidation of the ethers by cerium(IV) in concentrated sulphuric acid solution. The spin distributions and g values are similar to these in corresponding phenol radical cations. The 1,3-benzodioxoles give rise to particularly intense spectra which characteristically have triplet splittings close to 2.0 mT, which can be explained in terms of the molecular orbital theory of hyperconjugation. The relatively marked stability of the cations from the 1,3-benzodioxoles made it possible to obtain intelligible data from some complex natural products containing this group. Evidence from the spectra for various types of conformational isomerism is discussed.