80434-34-0Relevant academic research and scientific papers
Kinetics and mechanisms of the reactions of hypochlorous acid, chlorine, and chlorine monoxide with bromite ion
Nicoson, Jeffrey S.,Perrone, Thomas F.,Huff Hartz, Kara E.,Wang, Lu,Margerum, Dale W.
, p. 5818 - 5824 (2003)
The reaction between BrO2- and excess HOCl (p[H +] 6-7, 25.0 °C) proceeds through several pathways. The primary path is a multistep oxidation of HOCl by BrO2- to form ClO3- and HOBr (85% of the initial 0.15 mM BrO 2-). Another pathway produces ClO2 and HOBr (8%), and a third pathway produces BrO3- and Cl - (7%). With excess HOCl concentrations, Cl2O also is a reactive species. In the proposed mechanism, HOCl and Cl2O react with BrO2- to form steady-state species, HOClOBrO - and ClOClOBrO-. Acid facilitates the conversion of HOClOBrO- and ClOClOBrO- to HOBrOClO-. These reactions require a chainlike connectivity of the intermediates with alternating halogen-oxygen bonding (i.e. HOBrOClO-) as opposed to Y-shaped intermediates with a direct halogen-halogen bond (i.e. HOBrCl(O)O -). The HOBrOClO- species dissociates into HOBr and ClO2- or reacts with general acids to form BrOClO. The distribution of products suggests that BrOClO exists as a BrOClO·HOCl adduct in the presence of excess HOCl. The primary products, ClO 3- and HOBr, are formed from the hydrolysis of BrOClO·HOCl. A minor hydrolysis path for BrOClO·HOCl gives BrO3- and Cl-. An induction period in the formation of ClO2 is observed due to the buildup of ClO 2-, which reacts with BrOClO·HOCl to give 2 ClO2 and Br-. Second-order rate constants for the reactions of HOCl and Cl2O with BrO2- are k1HOCl = 1.6 × 102 M-1 s -1 and k1Cl2O = 1.8 × 105 M-1 s-1. When Cl- is added in large excess, a Cl2 pathway exists in competition with the HOCl and Cl2O pathways for the loss of BrO2-. The proposed Cl 2 pathway proceeds by Cl+ transfer to form a steady-state ClOBrO species with a rate constant of k1Cl2 = 8.7 × 105 M-1 s-1.
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
Catalytic reactions of chlorite with a polypyridylruthenium(ii) complex: Disproportionation, chlorine dioxide formation and alcohol oxidation
Hu, Zongmin,Du, Hongxia,Man, Wai-Lun,Leung, Chi-Fai,Liang, Haojun,Lau, Tai-Chu
, p. 1102 - 1104 (2012/02/17)
cis-[Ru(2,9-Me2phen)2(OH2) 2]2+ reacts readily with chlorite at room temperature at pH 4.9 and 6.8. The ruthenium(ii) complex can catalyze the disproportionation of chlorite to chlorate and chloride, the oxidation of chlorite to chlorine dioxide, as well as the oxidation of alcohols by chlorite. The Royal Society of Chemistry 2012.
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 (2009/09/08)
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
Effect of chloride ion on the kinetics and mechanism of the reaction between chlorite ion and hypochlorous acid
Kormanyos, Balazs,Nagypal, Istvan,Peintler, Gabor,Horvath, Attila K.
, p. 7914 - 7920 (2009/02/08)
The effect of chloride ion on the chlorine dioxide formation in the ClO2--HOCl reaction was studied by following ?ClO2 concentration spectrophotometrically at pH 5-6 in 0.5 M sodium acetate. On the basis of the earlier experimental data collected without initially added chloride and on new experiments, the earlier kinetic model was modified and extended to interpret the two series of experiments together. It was found that the chloride ion significantly increases the initial rate of ?ClO2 formation. At the same time, the ?ClO2 yield is increased in HOCl but decreased in ClO2- excess by the increase of the chloride ion concentration. The two-step hydrolysis of dissolved chlorine through Cl2 + H2O ? Cl 2OH- + H+ and Cl2OH- ? HOCl + Cl- and the increased reactivity of Cl 2OH- compared to HOCl are proposed to explain these phenomena. It is reinforced that the hydrolysis of the transient Cl 2O2 takes place through a HOCl-catalyzed step instead of the spontaneous hydrolysis. A seven-step kinetic model with six rate parameters (constants and/or ratio of constants) is proposed on the basis of the rigorous least-squares fitting of the parameters simultaneously to 129 absorbance versus time curves measured up to ～90% conversion. The advantage of this method of evaluation is briefly outlined.
Three autocatalysts and self-inhibition in a single reaction: A detailed mechanism of the chlorite-tetrathionate reaction
Horvath, Attila K.,Nagypal, Istvan,Epstein, Irving R.
, p. 9877 - 9883 (2008/10/09)
The chlorite-tetrathionate reaction has been studied spectrophotometrically in the pH range of 4.65-5.35 at T = 25.0 ± 0.2°C with an ionic strength of 0.5 M, adjusted with sodium acetate as a buffer component. The reaction is unique in that it demonstrates autocatalysis with respect to the hydrogen and chloride ion products and the key intermediate, HOCl. The thermodynamically most-favorable stoichiometry, 2S4O6 2- + 7ClO2- + 6H2O → 8SO 42- + 7Cl- + 12H+, is not found. Under our experimental conditions, chlorine dioxide, the chlorate ion, or both are detected in appreciable amounts among the products. Initial rate studies reveal that the formation of chlorine dioxide varies in an unusual way, with the chlorite ion acting as a self-inhibitor. The reaction is supercatalytic (i.e., second order with respect to autocatalyst H+). The autocatalytic behavior with respect to Cl- comes from chloride catalysis of the chlorite-hypochlorous acid and hypochlorous acid-tetrathionate subsystems. A detailed kinetic study and a model that explains this unusual kinetic behavior are presented.
Kinetics and mechanism of the oxidation of sulfite by chlorine dioxide in a slightly acidic medium
Horvath, Attila K.,Nagypal, Istvan
, p. 4753 - 4758 (2008/10/09)
The sulfite-chlorine dioxide reaction was studied by stopped-flow method at I = 0.5 M and at 25.0 ± 0.1 °C in a slightly acidic medium. The stoichiometry was found to be 2 SO32- + 2-ClO2 + H2O → 2SO42- + Cl- + ClO 3- + 2H+ in ClO2 excess and 6SO 32- + 2·ClO2 → S2O 62- + 4SO42- + 2Cl- in total sulfite excess ([S(IV)] = [H2SO3] + [HSO 3-] + [SO32-]). A nine-step model with four fitted kinetic parameters is suggested in which the proposed adduct SO3C1O22- plays a significant role. The pH-dependence of the kinetic traces indicates that SO32- reacts much faster with ClO2 than HSO3- does.
Spontaneous decomposition of industrially manufactured sodium hypochlorite solutions
Sizeneva,Kondrashova,Val'tsifer
, p. 541 - 545 (2007/10/03)
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.
