Kinetics of the oxidation of phenylhydrazine and phenylhydrazinesulfonic acids. Part II: Oxidation by cationic iron(III) complexes

The kinetics of the oxidation of phenylhydrazine and its sulfonic acids by cationic iron(III) complexes has been studied at constant temperature and ionic strenght in 0.1 to 1.0 M aqueous perchloric and hydrochloric acid. After correcting for associations, the reactions are first order in the iron(III) and the phenylhydrazines. Only the unprotonated phenylhydrazines are oxidized. All evidence points to an outer sphere mechanism for the reactions. Complex formation between metal ions (Fe3+, Mn2+, Ni2+) and the sulfonic acids seems to occur via the oxygen donor atoms of the sulfonic acid group.