14866-68-3Relevant academic research and scientific papers
Hypohalite ion catalysis of the disproportionation of chlorine dioxide
Wang, Lu,Margerum, Dale W.
, p. 6099 - 6105 (2002)
The disproportionation of chlorine dioxide in basic solution to give ClO2- and ClO3- is catalyzed by OBr- and OCl-. The reactions have a first-order dependence in both [ClO2] and [OX-] (X = Br, Cl) when the ClO2- concentrations are low. However, the reactions become second-order in [ClO2] with the addition of excess ClO2-, and the observed rates become inversely proportional to [ClO2-]. In the proposed mechanisms, electron transfer from OX- to ClO2 (k1OBr- = 2.05 ± 0.03 M-1 s-1 for OBr-/ClO2 and k1OCl- = 0.91 ± 0.04 M-1 s-1 for OCl-/ClO2) occurs in the first step to give OX and ClO2-. This reversible step (k1OBr-/k-1OBr- = 1.3 × 10-7 for OBr-/ClO2, k1OCl-/k-1OCl = 5.1 × 10-10 for OCl-/ClO2) accounts for the observed suppression by ClO2-. The second step is the reaction between two free radicals (XO and ClO2) to form XOClO2. These rate constants are k2OBr = 1.0 × 108 M-1 s-1 for OBr/ClO2 and k2OCl = 7 × 109 M-1 s-1 for OCl/ClO2. The XOClO2 adduct hydrolyzes rapidly in the basic solution to give ClO3- and to regenerate OX-. The activation parameters for the first step are ΔH1? = 55 ± 1 kJ mol-1, ΔS1? = - 49 ± 2 J mol-1 K-1 for the OBr-/ClO2 reaction and ΔH1? = 61 ± 3 kJ mol-1, ΔS1? = - 43 ± 2 J mol-1 K-1 for the OCl-/ClO2 reaction.
Photoinduced reaction between chlorine dioxide and iodine in acidic aqueous solution
Rabat, Gyula,Kovacs, Klara M.
, p. 6167 - 6170 (2001)
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.
New pathways for chlorine dioxide decomposition in basic solution
Odeh, Ihab N.,Francisco, Joseph S.,Margerum, Dale W.
, p. 6500 - 6506 (2002)
The product distribution from the decay of chlorine dioxide in basic solution changes as the ClO2 concentration decreases. While disproportionation reactions that give equal amounts of ClO2- and ClO3- dominate the stoichiometry at millimolar or higher levels of ClO2, the ratio of ClO2- to ClO3- formed increases significantly at micromolar ClO2 levels. Kinetic evidence shows three concurrent pathways that all exhibit a first-order dependence in [OH-] but have variable order in [ClO2]. Pathway 1 is a disproportionation reaction that is first order in [ClO2]. Pathway 2, a previously unknown reaction, is also first order in [ClO2] but forms ClO2- as the only chlorine-containing product. Pathway 3 is second order in [ClO2] and generates equal amounts of ClO2- and ClO3-. A Cl2O4 intermediate is proposed for this path. At high concentrations of ClO2, pathway 3 causes the overall ClO3- yield to approach the overall yield of ClO2-. Pathway 2 is attributed to OH- attack on an oxygen atom of ClO2 that leads to peroxide intermediates and yields ClO2- and O2 as products. This pathway is important at low levels of ClO2.
Kinetics and mechanism of catalytic decomposition and oxidation of chlorine dioxide by the hypochlorite ion
Csordas,Bubnis,Fabian,Gordon
, p. 1833 - 1836 (2001)
The oxidation of ClO2 by OCl-is first order with respect to both reactants in the neutral to alkaline pH range: -d[ClO2]/dt = 2kOCl[ClO2][OCl-]. The rate constant (T = 298 K, μ = 1.0 M NaCl
Spontaneous decomposition of industrially manufactured sodium hypochlorite solutions
Sizeneva,Kondrashova,Val'tsifer
, p. 541 - 545 (2005)
Spontaneous decomposition of industrially manufactured aqueous solutions of sodium hypochlorite was studied. The rate constants of the decomposition reactions were calculated for different pH values.
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 (2002)
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.
Concerted dismutation of chlorite ion: Water-soluble iron-porphyrins as first generation model complexes for chlorite dismutase
Zdilla, Michael J.,Lee, Amanda Q.,Abu-Omar, Mahdi M.
, p. 2260 - 2268 (2009)
Three iron-5,10,15,20-tetraarylporphyrins (Fe(Por-Ar4), Ar = 2,3,5,6-tetrafluro-N, N, N-trimethylanilinium (1), N, N, N-trimethylanilinium (2), and p-sulfonatophenyl (3)) have been investigated as catalysts for the dismutation of chlorite (CIO
Two-dimensional cluster catalysts with superior thermal stability and catalytic activity for AP
Guo, Yanli,Liang, Taixin,Liu, Wei,Song, Ruidong,Wang, Chao,Xiao, Fei,Zhang, Jiangbo
, (2022/01/08)
The preparation of catalysts with small particle size, large specific surface area and high atomic utilization has always been the focus of research in the field of catalysis. As for energetic materials, catalysts are always used to improve the thermal decomposition performance of ammonium perchlorate (AP) as it has significant effect on the power of engine. In this work, a two-dimensional metal clusters catalyst has been successfully prepared by solvothermal and heat treatment to improve thermal decomposition performance of AP. In detail, the transition metal ions were supported on the graphene oxide (GO) surface by organic ligands linking, followed by heat treatment to obtain two-dimensional rGO based metal clusters catalyst. The morphology and structure of the catalysts at different temperatures and their effect on AP decomposition were studied, the results show that catalyst at 300 °C has a particle size of 20 nm and uniformly distributed on rGO. The catalyst promotes the high temperature decomposition of AP by 73.7 °C with improved stability, and increases the heat release from 652.73 J/g to 1392.11 J/g. This may be attributed to good conductivity of GO and the strong gain-loss electron ability of the metal clusters. The presence of GO increased the active sites for cluster catalysis, additional, the metal clusters have a positive synergistic effect with GO. Thus, the thermal decomposition performance of AP was enhanced meanwhile thermal stability can also be improved.
Kinetics and mechanism of the chromium(VI) catalyzed decomposition of hypochlorous acid at elevated temperature and high ionic strength
Kalmár, József,Szabó, Mária,Simic, Nina,Fábián, István
, p. 3831 - 3840 (2018/03/21)
An important reaction step in the industrial production of NaClO3 (electrochemical chlorate process) is the thermal decomposition of HOCl/OCl- to yield ClO3- and Cl-. It is widely accepted that this reaction is accelerated by aqueous chromium(vi) species. A detailed kinetic study was conducted under industrially relevant conditions, i.e. at high ionic strength (6.0 M) and elevated temperature (80 °C), to investigate this phenomenon. The decomposition of hypochlorous acid was followed in the presence of Cr(vi) or phosphate (PO43-) or without any additive. In addition to the beneficial pH buffering effect of Cr(vi), the CrO42- form of chromium(vi) was found to slightly catalyze the decomposition of hypochlorous acid. The overall rate of HOCl decomposition can be expressed as -dcHOCl/dt = kdec[HOCl]2[OCl-] + kcat[HOCl]2[CrO42-]. The corresponding rate constants were determined, kdec = 9.4 ± 0.1 M-2 s-1 and kcat = 4.6 ± 0.8 M-2 s-1, and mechanistic interpretation of the catalytic rate law is given. The contribution of the catalytic path to the overall rate of decomposition changes from ca. 30% at pH = 8 to ca. 70% at pH = 6.
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
