Determination of bromide and nitrite by indirect redox titration using phenyl iodosoacetate

Abstract

Bromide has been determined by its oxidation with an excess of phenyl iodosoacetate in the presence of acetanilide to give bromine which subsequently reacts with acetanilide to form 4-bromoacetanilide. The residual amount of phenyl iodosoacetate was evaluated iodometrically. Thus, for every mol of bromide one mol of phenyl iodosoacetate was consumed. For the determination of bromine in organic compounds, the test substance was decomposed by fusion with alkali peroxide to liberate bromide which was then evaluated by the phenyl iodosoacetate method. For its determination, nitrite has been reacted with an excess of isoniazid in acid medium to form isonicotinyl azide (which does not react with phenyl iodosoacetate) and the residual amount of isoniazid was titrated with phenyl iodosoacetate in the presence of acidified bromide and methyl red indicator (when isoniazid and phenyl iodosoacetate react in a 1∶2 molar ratio). Each mol of nitrite is equivalent to 2 mol of phenyl iodosoacetate.