Spectrophotometric Identification and Determination of p-Phenylenediamine Type of Antioxidants in Vulcanised Rubber

A method has been proposed for the identification and quantitative determination of antioxidants, derived from p-phenylenediamine. It consists in the formation of a highly coloured solution, presumably Wurster's salt, by a reaction of the diamine derivative with acidic permanganate in ethanolic media, and measurement of the absorption with a spectrophoto­meter. The method has been found suitable for all the four antioxidants studied and also for the p-phenylenediamine derivative present as one of the components in a mixed antioxidant.