The kinetics and mechanism of oxidation of sulfanilic acid by hexacyanoferrate (III) catalyzed by osmium (VIII) and ruthenium (III) respectively have been studied spectrophotometrically. The uncatalyzed reaction simultaneously occurring in absence of these catalysts is suspected due to catalysis by any trace metal-ion present as an impurity either in the reagents or water. The rate of the reaction was also retarded by hexacyanoferrate (II).
The energy and entropy of activation were calculated in these reactions. A plausible reaction mechanism has been suggested in each case accounting for all the experimental observations.