15454-31-6Relevant articles and documents
Kinetics of the Oxidation of chromium(III) by Periodate
Abdel-Khalek, Ahmed A.,Elsemongy, Mahmoud M.
, p. 4407 - 4410 (1988)
The kinetics of oxidation of III(H2O)(TOH)>, (TOH=N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetate) by periodate in aqueous solutions has been found to obey the following equation: where k2 is the rate constant for
Photochemically induced autocatalysis in the chlorate ion-iodine system
Galajda, Monika,Lente, Gabor,Fabian, Istvan
, p. 7738 - 7739 (2007)
Light initiates an autocatalytic reaction sequence in the chlorate ion-iodine reaction. A previous report on the same system (Oliveira, A. P.; Faria, R. B. J. Am Chem. Soc. 2005, 127, 18022-18023.) failed to recognize the role of photoinitiation by the diode-array spectrophotometer used in the experiments. A mechanism is proposed to interpret the observations. Copyright
Disproportionation Kinetics of Hypoiodous Acid As Catalyzed and Suppressed by Acetic Acid-Acetate Buffer
Urbansky, Edward T.,Cooper, Brian T.,Margerum, Dale W.
, p. 1338 - 1344 (1997)
The kinetics of the disproportionation of hypoiodous acid to give iodine and iodate ion (5HOI ? 2I2 + IO3- + H+ + 2H2O) are investigated in aqueous acetic acid-sodium acetate buffer. The rate of iodine formation is followed photometrically at -log [H+] = 3.50, 4.00, 4.50, and 5.00, μ = 0.50 M (NaClO4), and 25.0°C. Both catalytic and inhibitory buffer effects are observed. The first process is proposed to be a disproportionation of iodine(I) to give HOIO and I-; the iodide then reacts with HOI to give I2. The reactive species (acetato-O)iodine(I), CH3CO2I, is postulated to increase the rate by assisting in the formation of I2O, a steady-state species that hydrolyzes to give HOIO and I2. Inhibition is postulated to result from the formation of the stable ion bis(acetato-O)iodate-(I), (CH3CO2)2I-, as buffer concentration is increased. This species is observed spectrophotometrically with a UV absorption shoulder (λ = 266 nm; ∈ = 530 M-1 cm-1). The second process is proposed to be a disproportionation of HOIO to give IO3- and I2. Above 1 M total buffer, the reaction becomes reversible with less than 90% I2 formation. Rate and equilibrium constants are resolved and reported for the proposed mechanism.
Pitfall of an initial rate study: On the kinetics and mechanism of the reaction of periodate with iodide ions in a slightly acidic medium
Horvath, Attila K.
, p. 890 - 896 (2007)
The kinetics of the periodate-iodide reaction has a contradictory history dating back to almost a century. This reaction has been reinvestigated spectrophotometrically in the pH range 3.13-5.55 in both buffered (acetic acid/acetate) and unbuffered solution at T = 25.0 ± 0.1 °C with an I = 0.5 M ionic strength. The spectra between 290 and 500 nm were recorded and the reaction was followed until at least 95% of one of the reactants was consumed. The stoichiometry has been found to be strongly dependent on pH, but the rate of the initial step is independent of pH within the pH range studied. An eight-step kinetic model is proposed with four fitted kinetic parameters to take all the important characteristics of the experimental curves into account. On the basis of the model, a perfect reconciliation of the previous contradictory results is presented. It is shown that the kinetic parameters obtained from the initial rate of formation of a product unavoidably leads to misinterpretation of the results in the case of a branching mechanism (and stoichiometry).
Oxidation of hexaaquoiron(II) by periodate in aqueous acidic solution
El-Eziri,Sulfab, Yousif
, p. 15 - 20 (1977)
The oxidation of Fe(II) by periodate in aqueous acidic solutions obeys the rate law (i) {A figure is presented} where [L6]T represents the total periodate concentration. The magnitudes of k0, k′1, k″2 and k3 are 0.235 sec-1, 120 sec-1, 7.5 ± 1.5 sec]-1, and (7.3 ± 0.5) X 104M-2 sec-1 respectively at 25 °C and I = 1.0 M. The terms in equation (i), that are first order in [L-]T, correspond to the oxidation process with possibly one-electron (term showing first order in [Fe(11)] and two electron-transfer (term showing second order in [Fe(II)]. At low [H+] (0.10 M), the pathway first order in [Fe(II)] predominates, whereas at high [H+] (0.80 M), the term second order in [Fe(II)] prevails. An explanation of the term independent of [L-]T is not quite obvious.
Mechanism for the Oscillatory Bromate-Iodide Reaction
Citri, Ofra,Epstein, Irving R.
, p. 357 - 363 (1986)
A mechanism is proposed for the reaction between bromate and iodide ions in acidic solution.The mechanism consists of 13 elementary steps and involves the interhalogen compound IBr but does not contain any radical species.Extensive numerical simulations show that the mechanism gives good agreement with the observed clock behavior in batch and with the bistability and oscillations observed in a CSTR.The present system appears to be the first in which bistability between a stationary and an oscillatory state has been succesfully described by a mechanism consisting of elementary steps.
Kinetics and Mechanism of the Chlorite-Periodate System: Formation of a Short-Lived Key Intermediate OClOIO3 and Its Subsequent Reactions
Baranyi, Nóra,Cseko, Gy?rgy,Valkai, László,Xu, Li,Horváth, Attila K.
, p. 2436 - 2440 (2016/03/19)
The chlorite-periodate reaction has been studied spectrophotometrically in acidic medium at 25.0 ± 0.1 °C, monitoring the absorbance at 400 nm in acetate/acetic acid buffer at constant ionic strength (I = 0.5 M). We have shown that periodate was exclusive
On the complexity of kinetics and the mechanism of the thiosulfate- periodate reaction
Rauscher, Evelin,Cseko, Gyoergy,Horvath, Attila K.
, p. 5793 - 5802 (2011/07/29)
The thiosulfate-periodate reaction has been studied spectrophotometrically in a slightly acidic medium at 25.0 ± 0.1 °C in an acetate/acetic acid buffer by monitoring the absorbance in the 250-600 nm wavelength range at a constant ionic strength adjusted by the buffer component sodium acetate. In agreement with a previous study, we found that the reaction cannot be described by a single stoichiometric equation, tetrathionate and sulfate are simultaneously formed, and its ratio strongly depends on the pH. As expected at certain initial concentration ratios of the reactants, the reaction behaves as a clock reaction, but after its appearance, iodine is slowly consumed mainly because of the moderate tetrathionate-iodine reaction. It is also enlightened that the initial rate of the reaction is completely independent of the pH, which apparently contradicts a previous study, which postulates a "supercatalytic" behavior of the hydrogen ion on the title reaction. Significant buffer assistance that may change the absorbance-time profiles was also observed. On the basis of the kinetic data, a robust 28-step kinetic model with 22 fitted parameters is proposed and discussed to explain adequately all of the important characteristics of the kinetic curves.
Photoinduced reaction between chlorine dioxide and iodine in acidic aqueous solution
Rabat, Gyula,Kovacs, Klara M.
, p. 6167 - 6170 (2007/10/03)
Photoinduced reaction between ClO2 and I2 has been discovered under illumination with 460 nm lightband. The photochemical reaction has a variable stoichiometry in acidic aqueous solution because the induced disproportionation of ClO2 to ClO3- and Cl- competes with the oxidation of I2 to IO3- by ClO2 in the illuminated reaction mixture. The reaction rate depends on the light power of illumination and on the concentration of I2, but it is independent of the concentration of ClO2. It is also independent of the pH in the range of 0-2.0 and of the ionic strength in the range of 0.01-1.0 M. Reversible dissociation of I2 has been identified as the primary photochemical process and rate-determining step in the mechanism. Reactive I atoms are considered to initiate fast reaction steps, leading to the formation of products through reactive intermediates such as IClO2, ClO, IO, and HOCl. This mechanism is proposed for explaining the photoresponses of the CDIMA oscillatory reaction system to the illumination with visible light.
A new type of oxyhalogen oscillator: The bromite-iodide reaction in a continuous flow reactor
Orbán, Miklós,Epstein, Irving R.
, p. 1252 - 1256 (2007/10/02)
The reaction between bromite and iodide ions in a flow reactor shows two steady states and sustained oscillations in pH, redox potential, and [I-]. The oscillatory behavior is extremely sensitive to the inflow ratio [BrO2-]/[I-], the flow rate, the initial pH of the input solutions, and the stirring rate. Batch experiments suggest that the system behaves in several respects like the analogous chlorite-iodide oscillator. The bromite-iodide system, however, is also a pH oscillator and is the first oxyhalogen oscillator to oscillate in the neutral and basic pH range.
