Nadeem B. Ganaie

Catalyst, Co-ion and the media effect on the oscillatory behavior of resorcinol in the BZ reaction

The study pertains to the oscillatory behavior of resorcinol as organic substrate in Belousov-Zhabotinsky (BZ) reaction in presence of different metal ions as catalysts in aqueous acid media. It is found that Mn2+ ion as catalyst is most reactive in comparison to ferroin (Fe2+). On varying the aqueous acid media, it is observed that protonated species with respect to organic substrate (resorcinol) is more easily formed in aqueous sulfuric acid, owing to which maximum number of oscillations are observed in this medium. Moreover, the effect of different anions like acetate, carbonate and sulfate associated with the same metal ion (Mn2+) as catalyst on the oscillatory behavior of the reaction system was also studied. Mixed mode oscillations are seen while changing concentration of aqueous sulfuric acid medium.

Kinetic studies on resorcinol-bromate-manganese(II) ion oscillator with and without additives

The present work pertains to the effect of temperature on the oscillatory behavior of bromate driven, Manganese (II) ion catalyzed BZ reaction with aromatic substrate i.e. resorcinol under batch conditions in 1.3 M sulfuric acid as aqueous acid medium. In order to study the effect of methyl ketones as additives (co-substrates), acetone is added to the aforesaid reaction system and the oscillations of the mixed substrate systems were studied at different temperatures. Further the effect of temperature with respect to ternary systems comprising of acetone with other ketones like butanone, pentanone, hexanone and acetyl acetone in 1:1 (v/v) ratio is also studied. It is found that temperature has a marked influence on the reactivity of the reaction systems, with and without methyl ketones and at all concentrations of the additives. Moreover, the rate of enolization of ketones also affects the oscillatory parameters like tin and tp. Although the exact values of enolization constants for the methyl ketones are not known to us, but by studying the oscillatory behavior, a trend can be predicted. Further the formation of end products in the ternary systems is influenced due to hydrophobic interactions of the ketones.

Effect of Temperature on Oscillatory Behaviour of the System Containing Isomers of Hydroxybenzoic Acid in Batch Reactor

In the present paper a thorough study of temperature dependence on oscillatory behaviour of the Belousov-Zhabotinsky (BZ) system containing the isomers of hydroxybenzoic acids

Dynamical regime of resorcinol based Belousov–Zhabotinsky chemical oscillator in the presence or absence of some hydrophobic antioxidants in aqueous–organic mixed media

This study aims to overcome the difficulty of using hydrophobic moieties like antioxidants, hormones, etc. in oscillatory chemical reactions due to existing solubility problems in aqueous acid media. Several new perturbants viz. hydrophobic antioxidants have been found to affect the oscillatory parameters under batch conditions in the resorcinol based Belousov–Zhabotinsky (BZ) oscillating system performed in aqueous–organic mixed media. The α-tocopherol, 4,4,4-trifluoro-3-methyl-2-butenoic acid, melatonin and β-carotene react with radicals either generated from BZ reagents or from the organic solvents and scavenge them. One to one interactions of these additives with resorcinol, bromate or Mn(II) ions have been investigated using cyclic voltammetry and potentiometry. These interactions may lead to a better understanding of their mechanism corresponding to their role in the BZ chemical oscillators. A comparative trend of these antioxidants was observed. It is noteworthy to mention here that radical based polymerization has been achieved using a specific solvent system containing monomers of that polymer and an interesting behavior oscillatory parameters was observed during polymer synthesis in situ.

Oscillatory behaviour of resorcinol with manganese salts in different aqueous acid media

Studies on the oscillatory behavior of resorcinol with different catalysts, different co-ions for the same catalyst (acetate, carbonate, sulphate) and different media give different trends. The use of different catalysts shows that Mn(II) is most reactive and Ferroin is least reactive with respect to resorcinol with respect to different oscillatory parameters like time period and induction period. The use of different acidic media clearly shows the ease with which protonated species is formed in sulfuric acid and hence maximum number of oscillations is seen in this medium as compared to orthophosphoric acid where no oscillations are seen. Study on the different co-ions is carried out for the first time and it is observed that co-ions also have a good impact on nature of oscillations. Such ions can be treated as co-substrates although oscillations are not observed while using such compound separately with the bromate (i.e. in absence of resorcinol).

Effect of Position and Number of Hydroxyl Groups on the Oscillatory Behaviour of Isomers of Hydroxybenzoic Acid

In the present communication, the effect of isomers of hydroxybenzoic acids with respect to their oscillatory behaviour as organic substrates with inorganic bromate and manganese(II) ion as catalyst in aqueous acid medium (1.0 M H2SO4) have been studied. The number and the relative position of hydroxyl groups (-OH) in the aromatic ring is found to influence the oscillatory behaviour. Besides, the role of bromination reaction and the formation of corresponding bromoderivative is found to be an important step. The experimental findings are within the purview of Field, Koros and Noyes (FKN) mechanism.