Polarography of carbonium ions in acid solution. Part I. The triphenylmethyl ion in sulphuric acid

Abstract

The triphenylmethyl cation in aqueous sulphuric acid is reduced at the dropping mercury electrode to triphenylmethane in a reversible two-electron step, if the protonation of the radical formed by the first one-electron uptake is sufficiently fast. ([H₂SO₄] > ca. 23N). When it is not ([H₂SO₄] < ca. 20N), the radical can be reduced further to triphenylmethane in a second one-electron step at more negative potentials. The triphenylmethane, formed by either route, can be reoxidised to the original cation. Dimerization of radicals competes with their protonation or reduction. Interpretation of the polarograms is complicated by maxima. Reversibility of the reductions was proved by the commutator method.