N-substituted phenothiazines as redox indicators in titrations with N-bromosuccinimide

Abstract

Butaperazine dimaleate, trifluoperazine dihydrochloride, diethazine hydrochloride, promethazine hydrochloride, prochlorperazine maleate and chlorpromazine hydrochloride are proposed as redox indicators in the macro- and micro-titration of hydroquinone, Metol (N-methyl-4-aminophenol sulphate) and ascorbic acid with N-bromosuccinimide in hydrochloric, sulphuric and acetic acids. They give very sharp and reversible colour changes at the equivalence point. A simple titrimetric method for the determination of hydroquinone, Metol and ascorbic acid and a potentiometric method for the determination of Metol are described.