REVERSIBLE TWO STEP OXIDATION

Abstract

In general, an organic dye stuff of quinoid structure is reduced by accepting from the reducing agent two hydrogen atoms or two electrons at once. Until recently no case had been known in which the reduction would occur in two separate steps in succession, each involving the acceptance of one electron (or hydrogen atom). This experience seemed to be quite natural and in agreement with the customary formulae, used in organic chemistry, for a quinoid or a benzoid compound. No intermediary form seemed to be imaginable, because one valence in this imaginary “semiquinoid” form would have to stand aloof and unsaturated: