New substrates in the ferroin‐catalyzed bromate system in aqueous‐organic mixed media

Lalitha, P.; Ramaswamy, R.

doi:10.1002/kin.550250605

Cited by 11 publications

(11 citation statements)

References 12 publications

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“…This can be attributed to the fused ring structure of flavones. The mechanism of the catalyzed bromate system in mixed media is found to be the same as that in pure aqueous medium, even though the oscillatory characteristics are altered in the presence of an organic solvent (15). As these substrates are not water soluble, a comparison of the oscillatory behaviour in mixed medium and pure aqueous medium could not be made.…”

Section: Results and Discussion (A) Gallic Acid As Substratementioning

confidence: 89%

“…(ii) Since it is water soluble, the study would enable a comparison of its dynamic behaviour in different mixed media as well as in pure aqueous medium. In fact, aqueous-organic media have been used successfully in the ferroin-catalyzed as well as the uncatalyzed bromate systems with gallic acid as substrate (15,16).…”

Section: Results and Discussion (A) Gallic Acid As Substratementioning

confidence: 99%

“…A systematic study of the aromatic bromate oscillators has been rendered difficult by the poor solubility of many organic compounds and the bromo derivatives in pure aqueous medium. This difficulty has been overcome by employing aqueous-organic mixed media, containing a small percentage of organic solvent in oscillatory systems (13)(14)(15)(16)(17)(18). This paper reports on the study of oscillatory behaviour of gallic acid in the Ce(II1)-catalysed system in nine different aqueous-organic mixed media.…”

Section: Introductionmentioning

confidence: 99%

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The oscillatory Belousov–Zhabotinsky reaction with flavones in batch systems using aqueous–DMF mixed medium

Maya¹,

Lalitha²,

Ramaswamy³

1994

Can. J. Chem.

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G. MAYA, P.V. LALITHA, and R. RAMASWAMY. Can. J. Chem. 72, 1537Chem. 72, (1994. Oscillatory systems of the Belousov-Zhabotinsky type with flavones as substrates are described for the first time. Since quercetin and morin are water insoluble, a mixed medium containing DMF and water was used with one of the three catalysts Ce(III), ferroin, or Mn(I1). The oscillatory behaviour of a water-soluble substrate (gallic acid) was studied in nine different aqueousorganic mixed media as well as in pure aqueous medium in the bromate-Ce(II1) system. The results obtained from a catalyzed system with quercetin or morin as the substrate in an aqueous-organic mixed medium are in agreement with the accepted (FKN) mechanism for an aqueous system. G. MAYA, P.V. LALITHA et R. RAMASWAMY. Can. J. Chem. 72, 1537 (1994). On dCcrit pour la premikre fois des systkmes oscillatoires du type Belousov-Zhabotinsky impliquant des flavones comme substrats. La quercktine et la morine Ctant insoluble dans l'eau, on a utilisk un milieu mixte contenant du DMF et de l'eau avec un des trois catalyseurs suivants: le Ce(III), la ferro'ine ou le Mn(I1). On a CtudiC le caractkre oscillatoire d'un substrat soluble dans l'eau (l'acide gallique) dans neufs milieux mixtes (eau/solvants organiques) ainsi que dans de l'eau pure dans le systkme bromatel Ce(II1). Les rksultats obtenus dans le systbme catalysC avec la quercCtine ou la morine comme substrats, dans un milieu mixte organique aqueux, sont conformes au micanisme accept6 (FKN) du systkme aqueux.[Traduit par la RCdaction]

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Section: Results and Discussion (A) Gallic Acid As Substratementioning

confidence: 89%

Section: Results and Discussion (A) Gallic Acid As Substratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The oscillatory Belousov–Zhabotinsky reaction with flavones in batch systems using aqueous–DMF mixed medium

Maya¹,

Lalitha²,

Ramaswamy³

1994

Can. J. Chem.

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“…As far as antioxidants more lipophilic than those studied here are concerned, it is our intention to study the behavior of the BR reaction and inhibitory effects in mixed organic/aqueous media (20% (v/v)) with other organic solvents as i-PrOH, THF, and MeCN where it has been reported that the well-known Belousov [21]-Zhabotinsky [22] reaction can occur [23].…”

Section: 2mentioning

confidence: 99%

Inhibitory Effects by Antioxidants on the Oscillations of the Briggs-Rauscher Reaction in Mixed EtOH/H2O Medium

Cervellati

Höner

Furrow

et al. 2002

HCA

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The Briggs-Rauscher (BR) oscillating reaction in mixed 20% EtOH/H 2 O (v/v) medium is studied together with the inhibitory effects by the addition of hydroalcoholic solutions of antioxidants on its oscillatory regime. As in aqueous BR mixtures, the inhibitory effect consists of an immediate cessation of oscillations, an inhibitory time that linearly depends on the concentration of the antioxidant added, and subsequent regeneration of oscillations. The effects of several water-insoluble and water-soluble antioxidants were investigated: at a parity of concentration of antioxidant added, inhibition times in the mixed EtOH/H 2 O medium are 2 ± 3 times lower than those reported previously in aqueous solution. However, the mechanism of the BR reaction, as far as that of the inhibitory effect, seems to be the same in either aqueous or mixed medium. The findings reported and discussed here are an indication that the analytical procedure to assess the activity of free radical scavengers based on the BR reaction can be extended to lipophilic antioxidants. Introduction. ± This paper is the third of a series [1] [2] concerning the inhibitory effects by antioxidants on the oscillations of the Briggs-Rauscher (BR) reaction [3], which consists of the iodination and oxidation of an organic substrate (in general, malonic acid (MA) or its derivatives) by acidic iodate in the presence of H 2 O 2 and with the Mn 2 ion as catalyst. The inhibitory effect consists of an immediate cessation of oscillations, an inhibition time that linearly depends on the concentration of the antioxidant added, and subsequent regeneration of oscillations.Among the main intermediates for which concentrations oscillate in the BR mixture, there is the hydroperoxyl radical HOO . . It was well-established that phenolic OH group(s) attached to ring structures present in several components of plants as well as in synthetic compounds are responsible for the antioxidant activity [4] against free radicals of oxygen. We have ascribed inhibitory effects on the oscillations of the BR reaction to scavenging of HOO . radicals by phenolic OH contained in the antioxidants added to an active BR mixture [1] [2]. The dependence of the inhibition time (i.e., the time elapsed between the cessation and the regeneration of the oscillatory regime) on the concentration of antioxidants added was found to be linear over a wide range of concentration [2].On the basis of inhibition times, it was possible to set up a new method (the BRreaction method) to assess the relative antioxidant activity with respect to a substance chosen as a standard [2]. This new method has been successfully tested on 16 German

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“…spectrophotometry [5,6], potentiometry [7], and thermometry [7][8][9][10]. In the recent past, a number of organic and mixed substrates have been used to obtain more informations regarding the mechanism of such reactions [11][12][13][14][15][16][17][18]. In our earlier communication [19], we have reported the temperature oscillation of bromate/gallic acid/sulfuric acid system as a function of bromate concentration with and without ferroin in a calorimeter with elaborate thermodynamic and mechanistic analysis of the results.…”

Section: Introductionmentioning

confidence: 99%

Oscillatory Reaction of Bromate-Gallic acid. A Calorimetric and Electrometric Study in Aquo-Organic Solvent Media

Biswas¹,

Mukherjee²,

Basu³

et al. 2001

Zeitschrift Für Physikalische Chemie

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B-Z Reaction / Gallic Acid / Ferroin / Enthalpy Change / Solvent and KCl EffectThe oscillatory reaction between potassium bromate and gallic acid (in presence of sulfuric acid and ferroin indicator) has been calorimetrically and potentiometrically studied in binary mixtures of water and organic solvents viz. dimethyl formamide, acetonitrile, tetrahydrofuran and 1,4-dioxan. The effects of solvent polarity, stirring condition, indicator concentration, aerial oxygen and chloride ion on the oscillatory process have been examined. The oscillatory behaviour of the reaction probed by the potentiometric method has a general agreement with the calorimetric method. An attempt has been made to determine the order of the Fe 2+ →Fe 3+ oxidation reaction. The damping coefficients of the oscillatory process in aqueous and mixed solvent media have been estimated.

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New substrates in the ferroin‐catalyzed bromate system in aqueous‐organic mixed media

Cited by 11 publications

References 12 publications

The oscillatory Belousov–Zhabotinsky reaction with flavones in batch systems using aqueous–DMF mixed medium

The oscillatory Belousov–Zhabotinsky reaction with flavones in batch systems using aqueous–DMF mixed medium

Inhibitory Effects by Antioxidants on the Oscillations of the Briggs-Rauscher Reaction in Mixed EtOH/H2O Medium

Oscillatory Reaction of Bromate-Gallic acid. A Calorimetric and Electrometric Study in Aquo-Organic Solvent Media

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