Complex kinetics and significant influences of bromine removal in ferroin–bromate–metol reaction

Abstract

This study presents a new bromate-based chemical oscillator that employs metol as the organic substrate. Complex reaction behaviors were observed when the system was subjected to bromine removal and oxygen exposure. Transitions from simple to sequential oscillations took place as a function of the age of the metol stock solution. MS spectroscopy measurements and parallel kinetic experiments with a mixture of metol and hydroquinone suggest that the decomposition of metol to hydroquinone was responsible for the observed influence of oxygen and the age of the metol solution. GS/MS and NMR measurements revealed that 1,4-benzoquinone and bromobenzoquinones were the major final products, regardless of the presence of oxygen and bromine removal. Preliminary exploration in a capillary tube showed some interesting propagating pulse behavior.

Current and potential oscillations during the electro-oxidation of bromide ions

“…On the other hand, the importance of bromide ions in chemical and electrochemical oscillations is well documented [5][6][7][8][9][10]. For example, oscillations have been observed during the electro-dissolution of gold in an electrolyte solution containing bromide ions [9].…”

Long-Lasting Complex Reaction Behavior in a Closed Ferroin–Bromate–Hydroxybenzenesulfonate System

“…The reaction behavior of several uncatalyzed bromate oscillators including the bromate–phenol system has been reported to exhibit great dependence on stirring. ,,− Such a dependence may arise from its influences on the extremely fast reaction steps or the influence on the diffusion of volatile species as well as oxygen out/into the reaction solution. It has previously been shown that oxygen can increase the induction period as well as gradually decrease the amplitude of the oscillatory behavior in the BZ oscillator. , To shed light on the effects of oxygen on this reaction, the reaction solution was first purged with nitrogen gas to remove any excess oxygen.…”

Complex Dynamical Behavior in the Highly Photosensitive Cerium–Bromate–1,4-Benzoquinone Reaction

“…29 Our earlier study has shown that bromine removal could have significant impact on the behavior of modified BZ reactions. 30 To examine whether the escape of volatile species played a key factor in causing the oscillatory behavior in the above reaction, we have run parallel experiments by flowing nitrogen or air above the reaction solution surface. Figure 2 presents the results achieved under the flow of air at 60 mL/ min.…”