An indirect coulometric determination of some aromatic amines with generated bromine

The possibilities of determining benzidine, 3, 3 ‘-dimethyl - benzidine, 1-naphtylamine and 2, 4-diaminotoluene with coulo-metrically generated bromine were studied. Conditions have been found for an indirect determination of 3, 3 -dimethylben-zidine and 2, 4-diaminotoluene based on the reaction with excess bromine. With 3, 3 -dimethylbenzidine, the unreacted bromine is reduced with excess arsenic (III) that is back-titrated with coulometrically generated bromine. With 2, 4-diamino-toluene, the excess bromine is titrated with copper (I) that is coulometrically generated in the same base electrolyte after changing the polarity of the generating electrode. Analytical use of the reactions of benzidine and 1-naphtylamine with bromine is prevented by non-stoichiometric courses of the reactions.