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Bromide Ion Impurity-Induced Reaction between Selenium(IV) and Acidic Bromate: Prototype of a Cycle with
György Csekő1, Attila K Horváth1
1Department of General and Inorganic Chemistry, Faculty of Sciences, University of Pécs, Ifjúság útja 6, H-7624 Pécs, Hungary.
Inorganic Chemistry
|January 16, 2024
Summary
The selenium(IV)-bromate reaction is autocatalytic, driven by trace bromide impurities. This unexpected finding reveals a new cycle where bromide ions regenerate, acting as a catalyst.
Area of Science:
- Chemical Kinetics
- Reaction Mechanisms
Background:
- The selenium(IV)-bromate reaction is a complex redox system.
- Understanding reaction pathways is crucial for chemical kinetics.
Purpose of the Study:
- To investigate the reaction mechanism of selenium(IV)-bromate in acidic medium.
- To clarify the difference between autocatalytic cycles and reactions.
Main Methods:
- UV-vis spectroscopy was used to monitor bromine formation.
- Kinetic traces were analyzed under varying reactant concentrations.
Main Results:
- The reaction exhibits sigmoidal or rise-and-fall behavior depending on reactant excess.
- A trace bromide impurity initiates an autocatalytic cycle, not a direct reaction.
- Bromide ions are regenerated, leading to an autocatalytic rise in their concentration.
Conclusions:
- The selenium(IV)-bromate system operates via an autocatalytic cycle initiated by bromide impurities.
- This cycle serves as a prototype for understanding autocatalysis.
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