Abstract
The stopped-flow method has been used to investigate the kinetics of the rapid reaction between manganese(III) and hydroquinone in aqueous perchlorate solution at 25°. The sole oxidation product was p-benzoquinone using spectrophotometric analysis, and the stoichiometry of the reaction corresponded to 2Mn(III)+ p-C6H4(OH)2→ 2Mn(II)+ p-C6H4O2+ 2H+. The reaction rate was first-order in each reactant, and was independent of variations in [Mn(III)]0, [p-hydroquinone]0, [Mn(II)], total ionic strength, [NaClO4], [NaNO3] and the presence of oxygen, at fixed acidity. Variation of acidity in the range [HClO4]= 0.60–3.60 M was used to determine the rate constants k1= 0.48 × 104 M–1 sec–1 and k1′= 3.28 × 104 M–1 sec–1 for reaction of Mn3+aq and MnOH2+aq with the hydroquinone molecule, respectively.