Collect. Czech. Chem. Commun. 1995, 60, 781-787

Design of Transition-Metal Oscillators Based on the Reduction of Permanganate Ions by Keto Dicarboxylic Acids

Milan Melicherčík, Marta Mrákavová, Arpád Nagy, Anna Olexová and Ľudovít Treindl

Department of Physical Chemistry, Comenius University, 842 15 Bratislava, Slovak Republic


Permanganate chemical oscillators with some keto dicarboxylic acids in the presence of phosphoric acid in a continuously stirred tank reactor (CSTR) are described in terms of the phase diagrams in the [ketomalonic acid]o-ko, [oxalacetic acid]o-ko, and [α-ketoglutaric acid]o-ko planes, and in the [H3PO4]o-ko , [MnO4-]o-ko , temperature-ko planes. The results show that an optimum degree of stabilization of the Mn(IV) colloid, which may serve as a reservoir of solvated Mn(IV) ions participating in the elementary reaction steps, is a prerequisite for the oscillations in the MnO4--keto dicarboxylic acid system. A skeleton mechanism for permanganate oscillators with keto dicarboxylic acids involving five reaction steps is proposed.