Redox reaction of iodine and phenols II microdetermination of phenols with iodine by potentiometry

ABSTRACT

A new rapid and accurate method for the determination of amino, nitro-and bromophenois is adopted. This is based on their oxidation with iodine aqueous ethanolic solution and titration of the iodide equivalent to the phenol derivative with mercury [II] using silver amalgam and SCE combination. The possible schemes for the course of the redox reactions are suggested. The procedure Is also evaluated, in comparison with those mentioned in the line rature. A series of experiments is performed for each phenol, a; the optimum conditions, covering a wide range of Its concentration. The mean deviation, the relative mean deviation and the coefficient of variation are calculated for the determination of p-amino-phenol to test the reproducibility of the suggested procedure. The standard deviation 0.002 indicates high accuracy of the present method. All end points are attended with large potential breaks ranging from 140 -240 mV/O.I ml of 0.05 M mercury [II]