7486-26-2Relevant articles and documents
Bromite ion catalysis of the disproportionation of chlorine dioxide with nucleophile assistance of electron-transfer reactions between ClO2 and BrO2 in basic solution
Wang, Lu,Nicoson, Jeffrey S.,Huff Hartz, Kara E.,Francisco, Joseph S.,Margerum, Dale W.
, p. 108 - 113 (2008/10/08)
The rate of ClO2 conversion to ClO2- and ClO3- is accelerated by BrO2-, repressed by ClO2-, and greatly assisted by many nucleophiles (Br- > PO43- > HPO42- > CO32- > Cl- ～ OH- > CH3COO- ～ SO42- C5H5N ? H2O). The kinetics (at p[H+] = 9.3-12.9) show that the first step of the mechanism is an electron transfer between ClO2 and BrO2- (k1 = 36 M-1 s-1) to give ClO2- and BrO2. This highly reversible reaction (k1/k-1 = 1 × 10-6) accounts for the observed inhibition by ClO2-. The second step is an electron transfer between ClO2 and BrO2 to regenerate BrO2- and form ClO3-. A novel aspect of the second step is the large kinetic contribution from nucleophiles (kNu) that assist the electron transfer between ClO2 and BrO2. The kNu (M-2 s-1) values at 25.0 °C vary from 2.89 × 108 for Br- to 2.0 × 104 for H2O.
On the Use of Ion-Selective Electrodes for Monitoring Oscillating Reactions. 2. Potential Response of Bromide- and Iodide-Selective Electrodes in Slow Corrosive Processes. Disproportionation of Bromous and Iodous Acids. A Lotka-Volterra Model for the Halate Driven Oscillators
Noszticzius, Z,Noszticzius, E.,Schelly, Z. A.
, p. 510 - 524 (2007/10/02)
The potential response of silver halide membrane electrodes to the corrosive bromous, bromic, iodous, and iodic acids is investigated in sulfuric acid solutions ( = 0.15 and 1.5 M), typical media for several well-known oscillating reactions.The syntheses of the materials (bromide-free NaBrO2 and HIO2) needed for the experiments are described.The potentials recorded as a function of time were used for the determination or estimation of several rate constants at 24 +/- 1 deg C: the disproportionation rate constant of HBrO2 is kB1 = (1.4 +/- 0.2) * 103 M-1 s-1 (in 0.15 M H2SO4) and (3.8 +/- 1.0) * 103 M-1 s-1 (in 1.5 M H2SO4): the corresponding value for HIO2 is KI1 -1 s-1 (in 0.05-0.15 M H2SO4); the disproportionation of HIO2 is autocatalytic, the rate-determining step is a reaction of HIO2 with H2OI+, the rate constant of which is kI5 = 130 +/- 5 M-1 s-1 ( in 0.15 M H2SO4); the rate constants of the reactions of HBrO2 with Br- and H+, and HIO2 with I- and H+ are 106 B2 6 M-2 s-1 (in 1.5 M H2SO4) and 106 I2 7 M-2 s-1 (in 0.15 M H2SO4), respectively.The corrosive reactions of the halous and halic acids with halide ions are much slower than those of hypohalous acids, which fact required the development of the theory for slow corrosive reactions.Criteria for the definitions of slow and fast corrosive reactions are given.The possibility of a second autocatalytic process in the halate driven oscillating reactions is demonstrated.On the basis of these results, a generalized Lotka-Volterra scheme is proposed for the BZ, BL, and BR oscillators.
