The oxidation of 3′,3″-dibromothymolsulfonphthalein (DBTS) in neutral medium by potassium permanganate multiequivalent oxidant has been studied spectrophotometrically. Pseudo-first-order plots showed inverted S-shape throughout the entire
course of the reaction. The initial rates were found to be relatively fast in the early stages, followed by a decrease in the oxidation
rates over longer time periods in the slow stage. Under pseudo-first-order conditions where [DBTS] ≫ 10 [MnO4-], the
experimental results showed a first-order dependence in [MnO4-] and fractional-first-order kinetics in the [DBTS] concentration.
The formation of 1:1 coordination intermediate complex prior to the rate-determining step was revealed kinetically. In addition, the
intermediate species involving complexes of Mn(V) coordination has been detected. The oxidation product of DBTS was identified
by Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometry, and gas chromatography-mass analysis. The
obtained results indicated the formation of 2-bromo-6-isopropyl-3-methyl-cyclohexa-2,5-dienone as a derivative oxidation of DBTS