Chemiluminescent stages of Belousov-Zhabotinskii reactions in systems with ruthenium complexes

Abstract

The autooscillatory catalytic oxidation of malonic acid (MA) by bromate (the Belousov-Zhabotinskii reaction) in the presence of the trisbipyridyl complexes of ruthenium Ru(II, III) is accompanied by bright chemiluminescence (CL) which appears during the reduction of the Ru(III) by the active intermediate products (organic radicals). It was shown that the chemiluminescence results from interaction of the Ru(III) not with MA radicals formed at the first stage of its oxidation but with stronger reducing agents, i.e., the radicals of hydroxymalonic acid and, probably, the ĊOCOOH and HĊO2 radicals. The main paths leading to the formation and consumption of these radicals are reactions involving the bromate. A simplified scheme is presented for the process leading to the appearance of chemiluminescence in the MABrO3−-Ce(III, III) and MA-BrO3−-Ce(III, IV)-Ru(II, III) systems. It confirms the experimental relatinships between the maximum intensity of the chemiluminescence and the concentrations of the reagents.