10049-04-4Relevant articles and documents
King, F. E.,Partington, J. R.
, (1926)
Absorption and fluorescence of OClO A2A2-X2B1 in solid Ne, Ar, and Kr. I. Vibrationally unrelaxed A→X emission
Liu, Chin-Ping,Lai, Lih-Huey,Lee, Ying-Yu,Hung, Shao-Ching,Lee, Yuan-Pern
, p. 978 - 987 (1998)
Dispersed laser-induced fluorescence of the A2A2→X2B1 transition of OClO in solid Ne in the spectral range 500-770 nm was recorded when the origin at 20991cm-1 was excited. Progressions with spacings near 939 and 446cm-1 are associated with vibrational modes ν1 and ν2 of the X state. A simultaneous fit of both modes yields ω1″=957.1±1.4, ω2″=452.6±0.4, x11″=4.47±0.04, x22″=0.54±0.05, and x12″=4.00±0.05cm-1. When the 101 line of the A-X system at 21699cm-1 was excited, vibrationally unrelaxed emission was observed in the spectral region 480-600 nm. Excitation of the 201 line at 21284cm-1 generated weak vibrationally unrelaxed progressions. The visible absorption spectrum of OClO in solid Ne in the region 415-488 nm was recorded with a Fourier-transform spectrometer, yielding ν00=20991.3, ν1′=707.9, ν2′=292.5, and 2ν3′=887.6cm-1 for the A state. Simultaneous fits considering either only ν1 and ν2 modes or all three modes yield corresponding spectral parameters. Similar experiments were performed with OClO in solid Ar and Kr. Pronounced increases in ν1′ (716.0cm-1 in Ar and 712.5cm-1 in Kr) and ν2′ (302.3cm-1 in Ar and 303.0cm-1 in Kr) and a decrease in ν00 (188cm-1 and 331cm-1 red-shifted, respectively) from that in the gas phase indicate substantial perturbation of the A state in solid Ar and Kr. An absorption continuum underlying the A-X system is attributed to absorption to the 12A1 state above the predissociation barrier. The phonon interaction increases and the threshold of the continuum decreases as the matrix host is altered from Ne to Ar to Kr.
Temperature Dependence and Mechanism of the Reaction between O(3P) and Chlorine Dioxide
Colussi, A. J.,Sander, S. P.,Friedl, R. R.
, p. 4442 - 4445 (1992)
Second-order rate constants for the decay of O(3P) in excess chlorine dioxide, k11, were measured by flash photolysis-atomic resonance fluorescence as a function of total pressure (20-600 Torr argon) and temperature (248 - 312 K).It was found that (1) k11 is pressure dependent with a value kb that is nonzero at zero pressure and (2) both the third order rate constant (dk11/d)=0 = k0 and kb have negative temperature dependences.These results are consistent with an association reaction leading to an intermediate having two decomposition channels:O + OClO ClO3* (1,2); ClO3* + M -> ClO3 + M (3); ClO3* -> ClO + O2* (4), with E02 > E04.The measured k0 values were used in conjunction with Troe's expression for unimolecular decomposition eates in the low-pressure limit to derive a critical energy for ClO3 of 10700 cm-1, which leads to Δ Hf(ClO3) = 51.9 +/- 5 kcal/mol.This is ca. 4 kcal/mol smaller than the value derived in our previous room temperature study of this reaction.
Outer-Sphere Electron-Transfer Reactions Involving the Chlorite/Chlorine Dioxide Couple. Activation Barriers for Bent Triatomic Species
Stabury, David M.,Lednicky, Lynn A.
, p. 2847 - 2853 (1984)
The kinetics of several redox reactions involving the ClO2/ClO2- couple have been determined in aqueous solution by stopped-flow spectrophotometry.ClO2 is reduced by 2+ to produce ClO2- and 3+ with simple bimolecular kinetics (k=2.1E7 M-1 s-1 at 25 deg C, μ=0.1 M (NaCF3SO3)).ClO2- is oxidized by IrCl62- to produce ClO2 and IrCl63-; the rate law is -d ln 2->/dt = k1/(1++>/Ka), with k1=1.06E4 M-1 s-1 and Ka=1.6E-2 M, the acid dissociation constant of HClO2.For the reaction of ClO2- with IrBr62- k1 is 1.86E4 M-1 s-1.Application of the Marcus-Hush cross relationship to these outer-sphere electron-transfer reactions leads to a self-consistent self-exchange rate constant of 1.6E2 M-1 s-1 for the ClO2/ClO2- couple.An explicit equation for the classical contributions of molecular vibrations to the activation free energy of self-exchange reactions of bent triatomic species has been derived.Calculations of these barriers show that both bending and stretching are important in the activation process.With this equation the activation barriers for the ClO2/ClO2-, NO2/NO2-, and SO2/SO2- redox couples have been rationalized.Nuclear tunneling introduces a correction to the classical rate constant by a factor of 79 for the NO2/NO2- couple.
The rapid interaction between sodium chlorite and dissolved chlorine
Emmenegger, Franzpeter,Gordon, Gilbert
, p. 633 - 635 (1967)
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Kinetics and Products of the BrO + ClO Reaction
Poulet, G.,Lancar, I. T.,Laverdet, G.,Bras, G. Le
, p. 278 - 284 (1990)
The overall rate constant of the BrO + ClO reaction has been measured by the discharge flow mass spectrometry method.The value found at 298 K is k1 = (1.13 +/- 0.15) x 10-11 cm3 molecule-1 s-1.Branchi
Photodissociation dynamics of OCIO
Davis, H. Floyd,Lee, Yuan T.
, p. 8142 - 8163 (1996)
Photofragment translational energy spectroscopy was used to study the dissociation dynamics of a range of electronically excited OCIO(A 2A2) vibrational states. For all levels studied, corresponding to OCIO(A 2A2←X 2B1) excitation wavelengths between 350 and 475 nm, the dominant product (>96%) was ClO(2Π)+O(3P). We also observed production of Cl+O2 with a quantum yield of up to 3.9±0.8% near 404 nm, decreasing at longer and shorter wavelengths. The branching ratios between the two channels were dependent on the OClO(A 2A2) excited state vibrational mode. The Cl+O2 yield was enhanced slightly by exciting A 2A2 levels having symmetric stretching+bending, but diminished by as much as a factor of 10 for neighboring peaks associated with symmetric stretching+asymmetric stretching. Mode specificity was also observed in the vibrationally state resolved translational energy distributions for the dominant ClO(2Π)+O(3P) channel. The photochemical dynamics of OClO possesses two energy regimes with distinctly different dynamics observed for excitation energies above and below ～3.1 eV (λ～400 nm). At excitation energies below 3.1 eV (λ>400 nm), nearly all energetically accessible ClO vibrational energy levels were populated, and the minor Cl+O2 channel was observed. Although at least 20% of the O2 product is formed in the ground (X 3∑-g) state, most O2 is electronically excited (a 1Δg). At E2A1 and 2B2. Long dissociation time scales and significant parent bending before dissociation led to nearly isotropic polarization angular distributions (β～0). At excitation energies above 3.1 eV (λ2 yield began to decrease sharply, with this channel becoming negligible at λa large fraction of the excess energy was channeled into C1O+O translational energy. The photofragment anisotropy parameter (β) also increased, implying shorter dissociation time scales. The sharp change in the disposal of excess energy into the ClO products, the decrease of Cl+O2 production, and more anisotropic product angular distributions at E>3.1 eV signify the opening of a new ClO+O channel. From our experimental results and recent ab initio calculations, dissociation at wavelengths shorter than 380 nm to ClO+O proceeds via a direct mechanism on the optically prepared A 2A2 surface over a large potential energy barrier. From the ClO(2Π)+O(3P) translational energy distributions, D0(O-ClO) was found to be less than or equal to 59.0±0.2 kcal/mol.
Vibrational mode-specific photochemical reaction dynamics of chlorine dioxide in solution
Fidder, Henk,Tschirschwitz, Frank,Duehr, Oliver,Nibbering, Erik T. J.
, p. 6781 - 6794 (2001)
The excited electronic state of OClO in solution was assessed. It was found that the fate of this state depends on which vibronic state is created. In general, the reaction dynamics scheme of OClO in solution that emerges from the data is far more complex
Calvert,Davies, E.
, p. 193 - 193 (1859)
Kinetics and Product Studies of the Reaction ClO + BrO Using Flash Photolysis-Ultraviolet Absorption
Sander, Stanley, P.,Friedl, Randall R.
, p. 4764 - 4771 (1989)
The flash photolysis-ultraviolet absorption method has been used to study the BrO + ClO reaction over the pressure range 50-700 Torr and temperature range 200-400 K.The rate constant for the overall reaction is given by k1=(6.1+/-1.2)x1E-12exp
Autocatalysis and self-inhibition: Coupled kinetic phenomena in the chlorite-tetrathionate reaction
Horvath, Attila K.,Nagypal, Istvan,Peintler, Gabor,Epstein, Irving R.
, p. 6246 - 6247 (2004)
The initial rate of formation of chlorine dioxide in the chlorite-tetrathionate reaction changes in an unusual fashion. The formal kinetic order of both reactants varies over a very wide range. Moreover, chlorite ion behaves not just as a simple reactant, but also as a self-inhibitor. A five-step scheme, derived from an eight-step mechanism, is proposed in which the autocatalytic formation of HOCl plays a central role in accounting for this kinetic behavior. Copyright
Kinetics and Mechanism of the Reaction between Chlorine(III) and Bromide Ion
Valdes-Aguilera, Oscar,Boyd, Donald W.,Epstein, Irving R.,Kustin, Kenneth
, p. 6702 - 6708 (1986)
The stoichiometry and kinetics of the reaction between chlorine(III) and bromide ion were studied spectrophotometrically at 25.0 +/- 0.5 deg C and ionic strength 1.2 M (NaClO4).The main products are Br3- and Cl- when bromide ion is in excess, ClO2 and Br2 when chlorine(III) is in excess.With sufficient acid and excess bromide ion, the stoichiometry of the reaction is HClO2 + 6Br- + 3H+ -> 2Br3- + Cl- +2H2O.The rate law for this reaction is (1/2)d->/dt = k+>-> where k = (9.51 +/- 0.14) * 10-2 s-1.When the reaction is carried out with > ->, the stoichiometry is difficult to define.In the range ca.= (1.50-2.00) * 10-3 M, -> ca.= 5.00 * 10-4 M, and ca.=0.20 M, a clock reaction occurs, the lag time of which decreases with addition of small amounts (-4 M) of molecular bromine.The complex rate law for the chlorine(III)-bromide ion reaction with excess Cl(III) can be explained by a 16-step mechanism including oxidation of bromide ion to bromine by chlorine(III), reduction of bromine to bromide ion, and decomposition of chlorous acid.A reduced set of 10 reactions and associated rate and equilibrium constants successfully modeled the clock reaction by computer simulation.
A kinetic study on reactions of OBrO with NO, OClO, and ClO at 298 K
Li, Zhuangjie,Tao, Zhining
, p. 117 - 123 (1999)
Kinetics for reactions of OBrO with NO, OClO, and ClO were examined using discharge flow coupled with mass spectrometer (DF/MS) technique at 298 K and total pressure of 1 torr under the pseudo-first-order condition in which OBrO was a minor reactant. The rate constant for the reaction of OBrO with NO was determined to be k2=(1.77±0.32)×10-12 cm3 molecule-1 s-1. NO2 was found to be the product for OBrO+NO. The rate constants for OBrO reactions with OClO and ClO were estimated to be k3-14 and k4-13 cm3 molecule-1 s-1, respectively.
Rollefson, G. K.,Byrns, A. C.
, p. 364 - 367 (1934)
Eachus, Raymond S.,Symons, Martyn C. R.
, (1976)
Oxidation of Chlorine(III) by Hypobromous Acid: Kinetics and Mechanism
Toth, Zsuzsanna,Fabian, Istvan
, p. 2717 - 2723 (2004)
The kinetics and mechanism of the chlorine(III)-HOBr reaction were studied by the stopped-flow method under acidic conditions, pH 1.0-3.0, in 1.0 M NaClO4 and at 25.0 °C. The overall redox process occurs in two consecutive steps via the formation of the BrClO2 intermediate. The electron transfer reactions are coupled with bromine hydrolysis, the formation of the tribromide ion, and the protolytic equilibrium of chlorine(III). On the basis of simultaneous evaluation of the kinetic traces, the following rate constants were obtained for the redox steps: HClO2 + HOBr ? BrClO2 + H2O, k3 = (3.34 ± 0.02) × 104 M-1 s-1, k-3 = (3.5 ± 1.3) × 103 s-1; BrClO2 + ClO2- ? 2ClO2 + Br-, k 4 = (2.9 ± 1.0) × 107 M-1 s -1. The second step was practically irreversible under the conditions applied, and the value of k-4 could not be determined. The equilibrium constant for the formation of BrClO2, K3 = 9.5 M-1, was calculated from the kinetic results, and it was confirmed that this species is a very powerful oxidant. The redox potential was also estimated for the BrClO2 + e- = Br- + ClO2 reaction: ε0o ～ 1.70 V.
Baluev, A. V.,Nikitina, Z. K.,Fedorova, L. I.,Rosolovskii, V. Ya.
, (1980)
Symons, Martyn C. R.,Zimmerman, Donald N.
, (1976)
Antioxidant chemistry: Oxidation of L-cysteine and its metabolites by chlorite and chlorine dioxide
Darkwa, James,Olojo, Rotimi,Chikwana, Edward,Simoyi, Reuben H.
, p. 5576 - 5587 (2004)
The oxidation of L-cysteine and its metabolites cystine and L-cysteinesulfinic acid by chlorite and chlorine dioxide has been studied in unbuffered neutral and slightly acidic media. The stoichiometry of the oxidation of L-cysteine was deduced to be 3ClO2- + 2H 2NCH(COOH)CH2SH → 3Cl- + 2H 2NCH(COOH)CH2SO3H with the final product as cysteic acid. The stoichiometry of the chlorite-cysteinesulfinic acid gave a ratio of 1:2, ClO2- + 2H2NCH(COOH)CH 2SO2H → Cl- + 2H2NCH(COOH) CH2SO3H. There was no further oxidation past cysteic acid, and there was no evidence of sulfate formation which would have indicated the cleavage of the carbon-sulfur bond. The reaction is oligooscillatory in chlorine dioxide formation. In conditions of excess oxidant, the reaction is characterized by a short induction period followed by a rapid and autocatalytic formation of chlorine dioxide. Chlorine dioxide is formed by the reaction of intermediate HOCl with the excess chlorite: 2ClO2- + 2HOCl + H- → 2ClO2(aq) + Cl- + H2O. Oligooscillations observed in chlorine dioxide formation result from the competition between this pure oxyhalogen reaction and reactions that consume chlorine dioxide. The rate of the reaction of chlorine dioxide with cysteine and its metabolites is fast and is of comparable magnitude with the reactions that form chlorine dioxide. The reaction of chlorine dioxide with L-cysteine is first order in both oxidant and substrate, retarded by acid, and has a lower-limit bimolecular rate constant of 405 ± 50 M-1 s-1, while for the reaction with L-cysteinesulfinic acid the rate constant is 210 ± 15 M-1 s-1. It would appear that the existence of a zwitterion on the asymmetric carbon atom precludes the formation of N-chloramines as has been observed with taurine and aminomethanesulfonic acid. The mechanism for the reaction is satisfactorily described by a network of 28 elementary reactions which include autocatalysis by HOCl.
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 (2006)
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.
Quantum yield for ClOO formation following photolysis of aqueous OClO
Thomsen,Reid,Keiding
, p. 12795 - 12801 (2000)
The photochemistry of chlorine dioxide (OClO) in aqueous solution was investigated by femtosecond transient absorption spectroscopy. Following the photoexcitation of OClO at 400 nm, the transient absorption dynamics were probed in the spectral range from 400 to 220 nm. As expected from earlier studies, the main photolytic products ClO + O, formed with a quantum yield of ～90%, disappear through fast geminate recombination producing OClO in the electronic ground state. The total quantum yield for chlorine atom production is (ΦCl) ～10%, with the chlorine atom production occurring through two competing processes. The dominant channel for chlorine atom production involves the formation of a short-lived intermediate on a ～6 ps time scale with a quantum yield of 8 ± 2%. The remaining 2 ± 1% is formed through the formation and decomposition of ClOO. The lifetime of ClOO was found to be ～0.32 ns, in very good agreement with the result of a recent time-resolved resonance Raman study. Finally, the UV absorption spectrum for aqueous ClOO is reported and compared with previously reported spectra obtained in condensed media.
CARS detection of ClO2
Zhang,Aker
, p. 765 - 767 (1994)
Coherent anti-Stokes Raman scattering (CARS) spectroscopy has been used to detect the v1 fundamental of gas-phase ClO2. CARS detection limits are reported. The results show that the CARS technique is ideally suited for gas-phase ClO
Kinetics and mechanism of the initial phase of the bromine - chlorite ion reaction in aqueous solution
Toth, Zsuzsanna,Fabian, Istvan
, p. 4608 - 4614 (2000)
The kinetics and mechanism of the chlorine(III)-bromine reaction are studied by the stopped-flow method under acidic conditions in 1.0 M NaClO4 and at 25.0 °C. There are two kinetically well-separated phases in this reaction. A detailed mechanism is proposed for the first phase of the reaction, in which Br2 oxidizes ClO2- to chlorine dioxide. It is confirmed that the oxidation occurs via competing parallel reaction steps. The autoinhibition observed in the reaction is attributed to a backward shift in the reversible initial step as the oxidation proceeds. On the basis of simultaneous evaluations of the kinetic traces, the following forward rate constants are obtained for the kinetically significant reaction steps: Br2 + ClO2- = ClO2 + Br2-, k1 = (1.3 ± 0.2) x 103 M-1 s-1 (k-1 = 1.1 x 109 M-1 s-1); Br2- + ClO2- = ClO2 + 2Br-, k2 = (4.0 ± 0.1) x 106 M-1 s -1; Br + ClO2- = ClO2 + Br-, k8 = (2.3 ± 0.7) x 108 M-1 s-1; HOBr + HClO2 = BrClO2 + H20 (BrClO2 + ClO2- = Br- + 2ClO2, very fast), k9 = (1.9 ± 0.1) x 105 M-1 s-1. The possible kinetic role of the reactive BrClO2 intermediate is discussed in detail.
Spinks, J. W. T.
, p. 129 - 139 (1940)
General-acid-catalyzed reactions of hypochlorous acid and acetyl hypochlorite with chlorite ion
Jia, Zhongjiang,Margerum, Dale W.,Francisco, Joseph S.
, p. 2614 - 2620 (2000)
The rate of oxidation of ClO2- by HOCl is first order in each reactant and is general-acid catalyzed. In the initial steps of the proposed mechanism, a steady-state intermediate, HOClOClO-, forms (k1 = 1.6 M-1 s-1) and undergoes general-acid (HA)-catalyzed reactions (k2(HA)) to generate a metastable intermediate, ClOClO. Values of k2(HA)/k-1 are 1.6 x 104 M-1 (H3O+), 20 M-1 (HOAc), and 8.5 M-1 (H2PO4-). Subsequent competitive reactions of ClOClO with ClO2- (k3) to give 2ClO2 and with OH- (k4(OH)) and other bases (k5(B)) to give ClO3- are very rapid. The relative yields of these products give k4(OH)/k3 = 1.3 x 105, k5(HPO)4/k3 = 0.20, and k5(OAc)/k3 = 0.06. At low pH and low buffer concentrations, the apparent yield of ClO2, based on 2ClO2 per initial HOCl, reaches 140%. This anomaly is attributed to the induced disproportionation of ClO2- by ClOClO to give ClO3- and additional HOCl. A highly reactive intermediate, ClOCl(O)OClO-, is proposed that can undergo Cl - O bond cleavage to give 2ClO2 + Cl- via one path and ClO3- + 2HOCl via another path. The additional HOCl recycles in the presence of excess ClO2- to give more ClO2. Ab initio calculations show feasible structures for the proposed reaction intermediates. Acetic acid has a second catalytic role through the formation of acetyl hypochlorite, which is much more reactive than HOCl in the transfer of Cl+ to ClO2- to form ClOClO.
AQUEOUS COMPOSITION AND METHOD OF PRODUCING CHLORINE DIOXIDE USING AQUEOUS COMPOSITION
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, (2018/07/15)
An aqueous composition includes an activator, a chlorite ion source, and water. The aqueous composition is alkaline. The aqueous composition produces chlorine dioxide upon contact with an acid. A method of producing chlorine dioxide includes contacting the aqueous composition with an acid.
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
Chemoselective catalytic oxidation of 1,2-diols to α-hydroxy acids controlled by TEMPO-ClO2 charge-transfer complex
Furukawa, Keisuke,Shibuya, Masatoshi,Yamamoto, Yoshihiko
supporting information, p. 2282 - 2285 (2015/05/13)
Chemoselective catalytic oxidation from 1,2-diols to α-hydroxy acids in a cat. TEMPO/cat. NaOCl/NaClO2 system has been achieved. The use of a two-phase condition consisting of hydrophobic toluene and water suppresses the concomitant oxidative cleavage. A study of the mechanism suggests that the observed selectivity is derived from the precise solubility control of diols and hydroxy acids as well as the active species of TEMPO. Although the oxoammonium species TEMPO+Cl- is hydrophilic, the active species dissolves into the organic layer by the formation of the charge-transfer (CT) complex TEMPO-ClO2 under the reaction conditions.
