Extractive-spectrophotometric determination of some 2- and 10-disubstituted phenothiazines with dipicrylamine.

Dipicrylamine reacts in neutral medium with some 2,10-disubstituted phenothiazines (promazine, chlorpromazine and promethazine hydrochlorides, trifluoperazine dihydrochloride, thioproperazine dimethanosulphonate) forming orange or brown ion-association compounds. The compounds are insoluble in water but quantitatively extracted into chloroform. These properties have been exploited for the determination of phenothiazines in pure solutions and pharmaceuticals.