Naphthidines and o-dianisidine as redox indicators in titrations with N-bromosuccinimide

Abstract

The optimum conditions for the successful use of naphthidine, 3,3′-dimethyl-naphthidine, 3,3′-dimethylnaphthidinedisulphonic acid and o-dianisidine as indicators in macro- and micro-titrations of hexacyanoferrate(II), iron(II), hydroquinone, metol and ascorbic acid with N-bromosuccinimide have been established. The indicators give a very sharp reversible colour change at the equivalence point and have advantages over the existing redox indicators. Hydrazinium sulphate and hydroxylammonium chloride have been determined indirectly. Anhydrous hexacyanoferrate(II) and iron(II) are suggested for the standardisation of N-bromosuccinimide solutions.