Double oscillations in reaction in bromate-manganese(II, III)-acetylacetone system

Abstract

The Belousov--Zhabotinskii oscillating chemical reactions with the participation of acetylacetone, a representative of the class of 8-diketones with an activated methylene group as the reducing agent, have several characteristic features. In a study of the oscillating reaction in the bromate--manganese(ll)--acetylacetone system it was found [1-4] that: i) the reaction proceeds without an induction period, 2) after consumption of the reducing agent and cessation of regular oscillations, chaotic oscillations of the measured characteristics are observed, 3) with simultaneous action of other reducing agents (malonic acid, ethyl acetonate) together with acatylacetone, acetylacetone is the first to enter the reaction, and only after its complete consumption does the next reducing agent react, rThe last fact, as well as spectrophotometric investigations [I], confirm the special role of the complexation between the manganese ions and acetylacetone. In [5, 6] it has already been shown that in the oscillating process in the Belousov--Zhabotinskii systems, complexation between the catalyst ions and the reducing agent plays an important role. To explain the role of this complexation, in the present work we carried out a comparative study of the parameters of the oscillating chemical reactions, with manganese(Ill) sulfate, manganese(II) acetylacetonate, and manganese(Ill) acetylacetonate serving as components.