Kinetic study of the Ce(III)-, Mn(II)- or Fe(phen)(3)(2+)-catalyzed Belousov-Zhabotinsky reaction with ethyl hydrogen malonate

In a stirred batch reaction, Fe(phen)(3)(2+) ion behaves differently from C e(III) or Mn (II) ion in catalyzing the bromate-driven oscillating reaction with ethyl hydrogen malonate [CH2COOHCOOEt, ethyl hydrogen malonate (EHM)] . The effects of N-2 atmosphere, concentrations of bromate ion, EHM, metal ion catalyst, sulfuric acid, and additive (bromide ion or bromomalonic acid ) on the pattern of oscillations were investigated, The kinetic study of th e reaction of EHM with Ce(IV), Mn(III), or Fe(phen)(3)(3+) ion indicates th at under aerobic or anaerobic conditions the order of reactivity toward rea ding with EHM is Mn(III) > Ce(IV) much greater than Fe(phen)(3)(3+), which follows the same trend as that of the malonic acid system. The presence of the ester group in EHM lowers the reactivity of the two methylene hydrogen atoms toward bromination or oxidation by Ce(IV), Mn(III), or Fe(phen)(3)(3) ion. No good oscillations were observed for the BrO3-CH2(COOEt)(2) reacti on catalyzed by Ce(III), Mn(II), or Fe(phen)(3)(2+) ion. A discussion of th e effects of oxygen on the reactions of malonic acid and its derivatives (R CHCOOHCOOR.) with Ce(IV), Mn(III), or Fe(phen)(3)(3+) ion is also presented . (C) 2000 John Wiley & Sons. Inc.