Competition between substitution and electron transfer in some 1,4-dialkoxybenzenes in concentrated sulphuric acid and the influence of the ortho-substituent on the β-proton splitting constants of their cation radicals

Abstract

The e.s.r. spectra of some 1,4-dialkoxy-2,5-dialkylbenzene cation radicals in concentrated sulphuric acid have been investigated. t-Butylation or isopropylation of 1,4-dimethoxy- or 1,4-diethoxy-benzenes in concentrated sulphuric acid occurs before electron transfer. 1,4-Dialkoxy-2,5-dialkylbenzene cation radicals are not susceptible to dealkylation. The influence of ortho-substituents on the β-proton splitting constants of these cation radicals is explained in terms of steric hindrance to rotation of the substituents.