O:Oxidizing agent;
7758-05-6Relevant articles and documents
Thermal decomposition of potassium metaperiodate doped with trivalent ions
Muraleedharan,Kannan,Gangadevi
, p. 24 - 29 (2010)
The kinetics of isothermal decomposition of potassium metaperiodate (KIO4), doped with phosphate and aluminium has been studied by thermogravimetry (TG). We introduced a custom-made thermobalance that is able to record weight decrease with time under pure isothermal conditions. The decomposition proceeds mainly through two stages: an acceleratory stages up to α = 0.50 and the decay stage beyond. The decomposition data for aluminium and phosphate doped KIO4 were found to be best described by the Prout-Tompkins equation. Separate kinetic analyses of the α-t data corresponding to the acceleratory region and decay region showed that the acceleratory stage gave the best fit with Prout-Tompkins equation itself whereas the decay stage fitted better to the contracting area equation. The rate of decomposition of phosphate doped KIO4 increases approximately linearly with an increase in the dopant concentration. In the case of aluminium doped KIO4, the rate passes through a maximum with increase in the dopant concentration. The α-t data of pure and doped KIO4 were also subjected to isoconversional studies for the determination of activation energy values. Doping did not change the activation energy of the reaction. The results favour an electron-transfer mechanism for the isothermal decomposition of KIO4, agreeing well with our earlier observations.
Thermal Decomposition of KIO4 and NaIO4 in Relation to Solid-state Isotopic Exchange Reactions
Takriti, Salaheddin,Duplatre, Gilles
, p. 2831 - 2842 (1988)
The thermal decomposition of KIO4 and NaIO4 has been studied.The decomposition product, KIO3 or NaIO3, suffers a very efficient exodiffusion during heating in such a way that the partly decomposed crystals consists of two parts: the outer part is a fragile layer of almost pure iodate, while the inner part is a solid crystalline lattice of almost pure periodate.The dimensions of the latter are not affected by the decomposition, so that its density decreases in proportion to the decomposed fraction.The decomposition isotherms present a saturation at long heating times which is not due to atmospheric effects, but is supressed when heating is performed with continuous removal of the outer layer.Kinetic analysis of the data shows a remarkable continuity between the exchange process, occurring at lower temperatures, and the decomposition.In paticular, the dimensionality of the reaction, n, from the Erofeev equation, ranges in KIO4 roughly from 1 to 2 with increasing temperature in the former case, then from 2 to 3 in the latter.These values are systematically higher by one unit in NaIO4, indicating that the nucleation process, which creates the driving defect, cannot be neglected as it can for KIO4.Both exchange and decomposition are dominated by the exodiffusion of some combined vacancy type defect, promoting the exodiffusion of the iodate and eventually triggering the decomposition; at sufficiently high temperature, the latter process becomes autocatalytic and develops three-dimensionally (n= 3 or 4).
Thorpe,Perry
, p. 925 - 925 (1892)
A new oscillatory mechanism for the electro-oxidation of iodide involving two phase transitions and a disproportional reaction
Chen, Shu,Huang, Wei,Niu, Zhenjiang,Li, Zelin
, p. 161 - 165 (2006)
Oscillations have been first observed during iodide oxidation in alkaline solution on a static platinum electrode, where phase transitions at the interface of electrode/solution are essential. The film formation of solid iodine acts as a negative nonlinear feedback slowing down the iodide oxidation due to its poor conductivity, and oxygen evolution as a positive nonlinear feedback by destroying the iodine film mechanically and by promoting its dissolution through convection mainly via a disproportional reaction. Based on the results of electrochemical experiments and in situ Raman spectroscopy, a tentative mechanism is given concerning the interfacial phase transitions and the disproportional reaction.
New approach to electrochemical iodination of arenes exemplified by the synthesis of 4-iodopyrazoles of different structures
Lyalin,Petrosyan
, p. 360 - 367 (2015/02/05)
The two-stage electrosynthesis of 4-iodosubstituted pyrazole derivatives was performed. At the first stage, KIO3 was obtained at the Ni anode under the undivided galvanostatic conditions of electrolysis of an aqueous alkaline solution of KI (or I2) at the Ni anode. At the second stage, pyrazole and its derivatives were iodinated in the heterophase (H2O-CHCl3 (CCl4)) medium by the KIO3-KI (or KIO3-I2) system in the presence of H2SO4. The yields of iodopyrazoles were 74-92%. The electrochemical iodination of anisole, 2-methylpyrazole, and thiophene was carried out to form 4-iodoanisole (88% yield), 4,5-diiodo-2-methylimidazole (54% yield), and a mixture of 2-iodothiophene (60% yield) and 2,5-diiodothiophene (4% yield).
