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 + BrO3-+ Mn(II) in aqueous acid medium (1.0 M H2SO4) at a fixed concentration of reacting species has been reported. On varying temperature, the oscillatory parameters like induction time, time period and number of oscillations show marked changes. These changes arise due to the position and number of hydroxyl groups in these isomers which affect the oscillations. Experimental observations have satisfactorily been explained by FKN mechanism and kinetic parameters. The oscillatory characteristics depend on the temperature dependence of the rate constant of the reaction controlling the inhibitory reaction steps (negative feedback)

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O presente trabalho estabelece e compara o comportamento oscilatório dos ácidos mono-, di-e trihidroxibenzóico, como substratos orgânicos em bromato-ácido (1,0 mol L -1 H 2 SO 4 ) sem catalisador e na presença de íon Mn 2+ como principal catalisador. As oscilações também são afetadas pelo uso de outro catalisador como íon Fe 2+ . Além disso, as oscilações diminuem em sistemas de catálise mista. Os parâmetros experimentais foram obtidos potenciometricamente e os resultados interpretados com base no mecanismo FKN.The present work establishes and compares the oscillatory behaviour of mono-, di-and trihydroxybenzoic acids as organic substrates in acidic bromate (1.0 mol L -1 H 2 SO 4 ) without catalyst and in the presence of Mn 2+ ion as the main catalyst. The oscillations are also affected by other catalyst such as Fe 2+ ion. Further, the oscillations start diminishing in mixed catalyst systems. The experimental parameters were obtained potentiometrically and the results have been interpreted on the basis of FKN mechanism.

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.