Benzylmalonic acid reaction with iodine and behavior in a Briggs–Rauscher oscillator

Cervellati, Rinaldo; Furrow, Stanley D.; Pompeis, Silvia De

doi:10.1002/kin.10062

Cited by 7 publications

(6 citation statements)

References 25 publications

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“…For this reason, the temperature of the reacting mixtures was monitored during all the reactions with a temperature sensor, then an average temperature was calculated. With regard to the noninhibited BR reaction, some studies have shown that the inverse of the oscillatory time (1/d) vs. the temperature T shows an Arrhenius behavior [11] [12]. This result was verified in the present work by using an uninhibited aqueous BR mixture that gave a long duration of oscillations, in order to study the dependence of this parameter on the temperature.…”

Section: Simulations For the Nonoscillating Subsystems Inhibitor Oxisupporting

confidence: 74%

An Experimental and Mechanistic Investigation of the Complexities Arising During Inhibition of the BriggsRauscher Reaction by Antioxidants

Cervellati

Höner

Furrow

et al. 2004

Helvetica Chimica Acta

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A method to determine the relative antioxidant capacity of radical scavengers based on the inhibition of the oscillations of the BriggsÀRauscher (BR) oscillating reaction was previously reported. A semiquantitative mechanistic interpretation of the inhibitory effects required two steps to obtain simulated inhibition times in very good agreement with the experimental ones. The first step is inhibitory, involving H-atom transfer from antioxidant to the HOO . radical; the second step is a first-order degradation of the antioxidant to unspecified products. Since the degradation may be due to oxidation and/or iodination of the antioxidant, we studied the kinetics of the subsystems IO À 3 (H ) antioxidant and I 2 (H ) antioxidant. We used 2,5-and 2,6-dihydroxybenzoic acids, caffeic acid ( 3-(3,4-dihydroxyphenyl)prop-2-enoic acid), ferulic acid ( 3-(4-hydroxy-3-methoxyphenyl)prop-2-enoic acid), pyrocatechol ( benzene-1,2-diol), and hydroquinone ( benzene-1,4-diol) as antioxidants. Spectra in the wavelength range 500 ± 250 nm were repeated at given time intervals to follow the peaks of the iodine and oxidation products, which were mainly quinones. For the iodination of the above diphenols ( benzenediol derivatives) the substitution and/or addition reactions with I 2 or HOI were found to be relatively slow compared to oxidation by IO À 3 . Approximate rate constants for oxidation were obtained on the basis of a reasonable kinetic model by using a suitable numerical integration program. Although these complexities can arise also in the completely inhibited BR oscillator, we believe that the inhibitory effects are due to the HOO . scavenging action by diphenols or by quinones since HOO . radicals are also potential reducing agents. We propose two steps that could maintain a small reservoir of diphenol, while both quinone and diphenol deplete HOO . radicals. In short, the complexities do not affect the method for monitoring the relative activity of antioxidants based on the BR oscillating reaction. The effects of temperature on the inverse of the oscillatory time in the BR-uninhibited system, on the inverse of inhibition times, and on the time length of the resumed oscillations for four antioxidants were also investigated. Apparent average activation energies were obtained.

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Section: Simulations For the Nonoscillating Subsystems Inhibitor Oxisupporting

confidence: 74%

An Experimental and Mechanistic Investigation of the Complexities Arising During Inhibition of the BriggsRauscher Reaction by Antioxidants

Cervellati

Höner

Furrow

et al. 2004

Helvetica Chimica Acta

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“…Activation energies from 60 to 90 kJ mol À1 have been reported for the Briggs-Rauscher reaction with different substrates. [25][26][27] Temperature coefficients from 0.67 to 1.80 were observed in a temperature interval of 10 1C for the oscillatory decomposition of hydrogen peroxide in an acidic aqueous solution in the presence of potassium iodate (Bray reaction). 28 It is important to point out that the apparent activation energy of about 60 kJ mol À1 estimated here under oscillatory conditions is of the same order than that obtained under voltammetric and chronoamperometric conditions.…”

Section: Resultsmentioning

confidence: 99%

Temperature effects on the oscillatory electro-oxidation of methanol on platinum

Carbonio

Nagao

González

et al. 2009

Phys. Chem. Chem. Phys.

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We report in this paper the effect of temperature on the oscillatory electro-oxidation of methanol on polycrystalline platinum in aqueous sulfuric acid media. Potential oscillations were studied under galvanostatic control and at four temperatures ranging from 5 to 35 degrees C. For a given temperature, the departure from thermodynamic equilibrium does not affect the oscillation period and results in a slight increase of the oscillation amplitude. Apparent activation energies were also evaluated in voltammetric and chronoamperometric experiments and were compared to those obtained under oscillatory conditions. In any case, the apparent activation energies values fell into the region between 50 and 70 kJ mol(-1). Specifically under oscillatory conditions an apparent activation energy of 60 +/- 3 kJ mol(-1) and a temperature coefficient q10 of about 2.3 were observed. The present findings extend our recently published report (J. Phys. Chem. A, 2008, 112, 4617) on the temperature effect on the oscillatory electro-oxidation of formic acid. We found that, despite the fact that both studies were carried out under similar conditions, unlike the case of formic acid, only conventional, Arrhenius, dynamics was observed for methanol.

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“…10,11 Growing attention has recently also been dedicated to the production of gas, [12][13][14] to some extent accompanying a vast majority of oscillating reactions, however, with particularly dramatic examples in the family of the BR reaction and its substitutions or additions. 8,[15][16][17] The BR reaction with acetone as the organic substrate has already been considered for its exceptionally well-defined oscillations in the rate of gas production and their practical measurement 18 and effects of the interphase transport of oxygen and iodine on the reaction have been modeled, 19 suggesting a possible interplay of the physical process of gas production and the chemistry of the reaction, which is normally neglected.…”

Section: Introductionmentioning

confidence: 99%

“…The core mechanism of the BR reaction has been considered to be established for the most part since the works of Furrow with Noyes and De Kepper with Epstein, who simultaneously proposed almost identical representations of the reaction, consisting of 11 pseudoelementary steps, as designed in eqs R1−R11 of Table , although its detailed examination remains a fruitful field even today. , Growing attention has recently also been dedicated to the production of gas, – to some extent accompanying a vast majority of oscillating reactions, however, with particularly dramatic examples in the family of the BR reaction and its substitutions or additions. ,– The BR reaction with acetone as the organic substrate has already been considered for its exceptionally well-defined oscillations in the rate of gas production and their practical measurement and effects of the interphase transport of oxygen and iodine on the reaction have been modeled, suggesting a possible interplay of the physical process of gas production and the chemistry of the reaction, which is normally neglected.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Interactions Between Iodine Interphase Transport and Oxygen Production in the Modified Briggs−Rauscher Reaction with Acetone

Szabo

Ševčı́k

2010

J. Phys. Chem. A

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Novel aspects of influence of gas evolution on oscillating chemical reaction are considered on a model of the modified Briggs-Rauscher reaction with acetone. The mechanism proposed by Noyes with Furrow and De Kepper with Epstein, adapted for acetone and expanded with oxygen evolution and first-order escape of iodine by interphase transport, was subjected to further extension, and calculations assuming direct proportionality of the rate of iodine escape on the surface area of the oxygen gas trapped in the solution as well as calculations considering first-order back-flow of iodine from the gas phase into the solution were performed. Furthermore, the concentrations of iodine vapors were considered to be variable within the bubble population, as all the bubbles are not in contact with the reaction mixture for the same length of time. Distribution functions of the surface size over the range of concentrations of iodine in the contacting gas phase were introduced and derived, and whereas they were proved not to play any role in the total intensity of iodine return when it is first-order, the article also demonstrates their explicit consideration in calculations to be essential if the dependence of the rate of iodine return into the solution on its concentration is not linear, for example, in future extensions of the model with bubble radius also considered variable.

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Benzylmalonic acid reaction with iodine and behavior in a Briggs–Rauscher oscillator

Cited by 7 publications

References 25 publications

An Experimental and Mechanistic Investigation of the Complexities Arising During Inhibition of the BriggsRauscher Reaction by Antioxidants

An Experimental and Mechanistic Investigation of the Complexities Arising During Inhibition of the BriggsRauscher Reaction by Antioxidants

Temperature effects on the oscillatory electro-oxidation of methanol on platinum

Modeling of Interactions Between Iodine Interphase Transport and Oxygen Production in the Modified Briggs−Rauscher Reaction with Acetone

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