A Study of the Cerium-catalyzed Briggs-Rauscher Oscillating Reaction

Abstract

Cerium(III) catalysts can replace manganese(II) in the classic Briggs-Rauscher oscillator also containing acid, iodate, hydrogen peroxide, and malonic acid. H 2 SO 4 was used as an acid; if HClO 4 is used, cerium iodate precipitates. Cerium(III) oxalate typically precipitates by the time oscillations end. Ce(III) at low concentrations is roughly three times as effective as Mn(II). At higher catalyst concentrations, there is a leveling effect for both. Oscillatory behavior with different concentrations is explored. Response to concentration change and inhibitors is similar with both catalysts. The mechanistic steps involving the catalysts must be similar. Ce(IV) is also an effective catalyst, although some cerium(IV) iodate may precipitate immediately.

The Briggs–Rauscher Reaction: A Demonstration of Sequential Spatiotemporal Patterns

“…To understand the origin of the patterns observed, it is useful to analyze the mechanistic origin for both BR (and BL) batch oscillations and the chemo-hydrodynamic characteristics. Batch oscillations for hydrogen peroxide decomposition are driven by HIO 2 autocatalysis. − After oscillations end, the transition from state I (low [I 2 ] and [I – ]) to state II (high [I 2 ] and [I – ]) occurs after a time delay at R ≪ 2. ,, Meanwhile, I – autocatalysis occurs via reactions (eqs and ), where X in eq denotes the agent consuming iodine and hypoiodous acid such as water, hydrogen peroxide, malonic acid, or iodomalonic acid from eq to eq , and Y and P are the general terms for the other products in eq and eq , respectively. The process in eq can be decomposed into two paths: ( + ) and ( + 0.5 + 0.5 + ).…”

“…23−25 After oscillations end, the transition from state I (low [I 2 ] and [I − ]) to state II (high [I 2 ] and [I − ]) occurs after a time delay at R ≪ 2. 21,26,27 Meanwhile, I − autocatalysis occurs via reactions (eqs R4 and R5), where X in eq R5-1 denotes the agent consuming iodine and hypoiodous acid such as water, hydrogen peroxide, malonic acid, or iodomalonic acid from eq R5-1 to eq R5-5, and Y and P are the general terms for the other products in eq R5-1 and eq R5-5, respectively.…”

A Briggs-Rauscher Reaction-based Spectrometric Assay to Determine Antioxidant Content in Complex Matrices in Low Technology Environments

“…Each potentiometric cycle is reliable, typically lasting 10-30 seconds, thus potentiometric methods have been developed to study the antioxidant concentration in complex matrices. [9][10][11][12][13][14][15] However, potentiometric measurement require platinum, silver or other similar electrodes that are not readily available in educational settings. This idea of using BR reaction to quantify antioxidant can be made simpler for use to the wider student and agricultural communities if potentiometric measurements can be replaced by color change, which can be monitored visually or be coupled with a simple spectrometer that is widely available.…”

Multiple iodide autocatalysis paths of chemo-hydrodynamical patterns in the Briggs–Rauscher reaction

“…Actually, H 2 O 2 as an oxidizing agent does not directly react with I 2 , but with HOI. 15–17 The mechanism of the subsystem in the BR reaction systems has been investigated by many reseachers 16–23 for elucidating the oscillatory behavior. In addition, after the ending of oscillations, the system may undergo a sudden transition from a state with low [I 2 ] and [I − ] (Type I) to a state with high [I 2 ] and [I − ] (Type II) through autocatalysis at certain conditions.…”