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Abstract

In the Belousov-Zhabotinskii oscillation reaction with 2,4-pentanedione and Mn²⁺ /Mn³⁺ redox catalyst, also the enol form of the substrate has an oscillating concentration. The decrease of the concentration of the enol form is due to its reaction with bromine and Mn³⁺ ions; its increase corresponds to the reestablishment of the keto-enol equilibrium, when the concentrations of bromine and Mn³⁺ ions are low. An oscillating time-course was observed also with the concentration of the intermediate product of the reaction, of 2,4-pentanedione with Mn³⁺ ions, probably an intermediate complex [Mn(III)-enol], which oscilated with a phase shift against Mn³⁺ ions.