The kinetics of oxidation of p-aminodiphenylamine with the peroxydisul
phate ion were investigated spectrophotometrically. The oxidation was
accompanied by the appearance of a wine-red colour, which changed to b
ecome colourless. ne reaction rate was measured by the stopped-flow te
chnique with a UV spectrophotometer. The reactions proceeded with seco
nd-order kinetics, first-order for each individual reactant. Cationic
micelles (cetyltrimethyl ammonium bromide) caused an enhancement in th
e reaction rate followed by inhibition at higher concentrations. Anion
ic micelles (sodium dodecyl sulphate), on the other hand, had a slight
ly retarding effect. The effects of radical scavenger, pH and ionic st
rength on the fast oxidation mte were examined. A mechanism consistent
with the observations is discussed.