Aromatic sulphonation. Part XLIII. Selenonation and sulphonation of polyalkylbenzenes with selenic and sulphuric acids in acetic anhydride

Abstract

The selenonation of a series of polyalkylbenzenes with a mixture of H₂SeO₄ and acetic anhydride (i.e. with acetylselenic acid) at 0° has been studied. The isomer distributions of the selenonic acids are similar to those determined for sulphonation with acetylsulphuric acid as reagent. The isomer distributions indicate high selectivity for the two substitutions. The n.m.r. spectra of the polymethylbenzene-selenonic and -sulphonic acids in water are almost identical, illustrating that the shielding parameters of the SeO₃^– and SO₃^– groups on aromatic hydrogen atoms and methyl groups are about the same.