Kinetics and Mechanism Studies of Oxidation of Dibromothymolsulfonphthalein Toxic Dye by Potassium Permanganate in Neutral Media with the Synthesis of 2-Bromo-6-isopropyl-3-methyl-cyclohexa-2,5-dienone

Hazim M Ali; Mohamed Abd El-Aal; Ahmed F Al-Hossainy; Samia M Ibrahim

doi:10.1021/acsomega.2c01462

Kinetics and Mechanism Studies of Oxidation of Dibromothymolsulfonphthalein Toxic Dye by Potassium Permanganate in Neutral Media with the Synthesis of 2-Bromo-6-isopropyl-3-methyl-cyclohexa-2,5-dienone

ACS Omega. 2022 Apr 28;7(18):16109-16115. doi: 10.1021/acsomega.2c01462. eCollection 2022 May 10.

Authors

Hazim M Ali¹, Mohamed Abd El-Aal², Ahmed F Al-Hossainy³, Samia M Ibrahim³

Affiliations

¹ Department of Chemistry, College of Science, Jouf University, P.O. Box 2014, Sakaka 72388, Aljouf, Saudi Arabia.
² Catalysis and Surface Chemistry Lab, Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt.
³ Chemistry Department, Faculty of Science, New Valley University, El-Kharga, New Valley 72511, Egypt.

Abstract

The oxidation of 3',3″-dibromothymolsulfonphthalein (DBTS) in neutral medium by potassium permanganate multi-equivalent 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.