- Absorption and fluorescence of OClO A2A2-X2B1 in solid Ne, Ar, and Kr. I. Vibrationally unrelaxed A→X emission
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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.
- Liu, Chin-Ping,Lai, Lih-Huey,Lee, Ying-Yu,Hung, Shao-Ching,Lee, Yuan-Pern
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- Formation and Decay of (3PJ)O Atoms in the Laser Flash Photolysis of Chlorine Dioxide (OClO) at 308 nm
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The primary quantum yields of O(3PJ) and Cl(2P3/2) atoms in the laser flash photolysis of OClO(g) at 308 nm and 298 K and the kinetics of the subsequent oxygen atom decay have been investigated by time-resolved atomic resonance fluorescence measurements.The determined quantum yields are ΦO = 1.02 +/- 0.05 and ΦCl a finite intercept.The rate constant for the bimolecular channel O + OClO -> O2 + ClO (1) has a value of k1 = (1.6 +/- 0.4) * 10-13 cm3 molecule -1s-1.Termolecular reaction rates for O + OClO + Ar -> ClO3 + Ar (2) can be fit with k20 = (1.4 +/- 0.3) * 10-31 cm6 molecule-2s-1 and k2infinite = (3.1 +/- 0.8) * 10-11 cm3 molecule-1 s-1.A value of ΔHf(ClO3) = 55.6 +/- 4 kcal/mol is derived from k20 and unimolecular reaction theory by assuming a collision efficiency of β = 0.76 for argon.
- Colussi, A. J.
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- Temperature Dependence and Mechanism of the Reaction between O(3P) and Chlorine Dioxide
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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.
- Colussi, A. J.,Sander, S. P.,Friedl, R. R.
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- Outer-Sphere Electron-Transfer Reactions Involving the Chlorite/Chlorine Dioxide Couple. Activation Barriers for Bent Triatomic Species
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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.
- Stabury, David M.,Lednicky, Lynn A.
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- Kinetics and mechanisms of the ozone/bromite and ozone/chlorite reactions
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Ozone reactions with XO2- (X = Cl or Br) are studied by stopped-flow spectroscopy under pseudo-first-order conditions with excess XO2-. The O3/XO2- reactions are first-order in [O3] and [XO2-], with rate constants k1Cl = 8.2(4) × 106 M-1 s-1 and k1Br = 8.9(3) × 104 M-1 s-1 at 25.0 °C and μ = 1.0 M. The proposed rate-determining step is an electron transfer from XO2- to form XO2 and O3-. Subsequent rapid reactions of O3- with general acids produce O2 and OH. The OH radical reacts rapidly with XO2- to form a second XO2 and OH-. In the O3/CIO2- reaction, CIO2 and CIO3- are the final products due to competition between the OH/CIO2- reaction to form CIO2 and the OH/CIO2 reaction to form CIO3-. Unlike CIO2, BrO2 is not a stable product due to its rapid disproportionation to form BrO2- and BrO3-. However, kinetic spectra show that small but observable concentrations of BrO2 form within the dead time of the stopped-flow instrument. Bromine dioxide is a transitory intermediate, and its observed rate of decay is equal to half the rate of the O3/BrO2- reaction. Ion chromatographic analysis shows that O3 and BrO2- react in a 1/1 ratio to form BrO3- as the final product. Variation of k1X values with temperature gives ΔH?Cl = 29(2) kJ mol-1, ΔS?Cl = -14.6(7) J mol-1 K-1, ΔH?Br = 54.9(8) kJ mol-1, and ΔS?Br = 34(3) J mol-1 K-1. The positive ΔS?Br value is attributed to the loss of coordinated H2O from BrO2- upon formation of an [O3BrO2-]? activated complex.
- Nicoson, Jeffrey S.,Wang, Lu,Becker, Robert H.,Hartz, Kara E. Huff,Muller, Charles E.,Margerum, Dale W.
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- Kinetics and Products of the BrO + ClO Reaction
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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
- Poulet, G.,Lancar, I. T.,Laverdet, G.,Bras, G. Le
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- Fourier Transform Ultraviolet Absorption Spectroscopy of Jet-Cooled OClO
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The jet-cooled A(2A2) (2B1) absorption spectrum of OClO has been measured with an apparatus that combines a high-resolution Fourier transform UV spectrometer with a high-throughput, continuous molecular jet.The results reported here demonstrate the sensitivity of Fourier transform direct absorption techniques to the investigation of the excited-state dynamics of dissociative systems.Structural and dynamical information is obtained from the jet-cooled absorption spectra of the A transition of OClO.Rotational line width broadening due to predissociation is measured in the higher energy bands up to and beyond the Frank-Condon maximum at ca. 28500 cm-1.The resolution and sensitivity of this absorption technique for the study of the electronic spectroscopy of highly reactive molecules are dicussed.
- Richard, EriK C.,Wickham-Jones, C. Tom,Vaida, Veronica
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- Photodissociation dynamics of OCIO
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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.
- Davis, H. Floyd,Lee, Yuan T.
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- Vibrational mode-specific photochemical reaction dynamics of chlorine dioxide in solution
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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
- Fidder, Henk,Tschirschwitz, Frank,Duehr, Oliver,Nibbering, Erik T. J.
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- Short-wavelength photolysis of jet-cooled OClO(2A2 v1>20) →ClO(X2ΠΩ,v,J) + O(3PJ)
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Velocity map imaging was used to study the energy partitioning and anisotropy for the ClO (X2Π)+O (3P2) product channel. Very high anisotropy parameters and extreme channeling of available energy were found. This observation indicates a fundamental change of the fragmentation dynamics of OClO near UV absorption band.
- Delmdahl, Ralph F.,Parker, David H.,Eppink, Andre T. J. B.
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- Kinetics and Product Studies of the Reaction ClO + BrO Using Flash Photolysis-Ultraviolet Absorption
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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
- Sander, Stanley, P.,Friedl, Randall R.
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- Dissection of the mechanism of manganese porphyrin-catalyzed chlorine dioxide generation
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Chlorine dioxide, an industrially important biocide and bleach, is produced rapidly and efficiently from chlorite ion in the presence of water-soluble, manganese porphyrins and porphyrazines at neutral pH under mild conditions. The electron-deficient manganese(III) tetra-(N,N-dimethyl)imidazolium porphyrin (MnTDMImP), tetra-(N,N-dimethyl)benzimidazolium (MnTDMBImP) porphyrin, and manganese(III) tetra-N-methyl-2,3-pyridinoporphyrazine (MnTM23PyPz) were found to be the most efficient catalysts for this process. The more typical manganese tetra-4-N-methylpyridiumporphyrin (Mn-4-TMPyP) was much less effective. Rates for the best catalysts were in the range of 0.24-32 TO/s with MnTM23PyPz being the fastest. The kinetics of reactions of the various ClOx species (e.g., chlorite ion, hypochlorous acid, and chlorine dioxide) with authentic oxomanganese(IV) and dioxomanganese(V)MnTDMImP intermediates were studied by stopped-flow spectroscopy. Rate-limiting oxidation of the manganese(III) catalyst by chlorite ion via oxygen atom transfer is proposed to afford a trans-dioxomanganese(V) intermediate. Both trans-dioxomanganese(V)TDMImP and oxoaqua-manganese(IV)TDMImP oxidize chlorite ion by 1-electron, generating the product chlorine dioxide with bimolecular rate constants of 6.30 × 10 3 M-1 s-1 and 3.13 × 103 M-1 s-1, respectively, at pH 6.8. Chlorine dioxide was able to oxidize manganese(III)TDMImP to oxomanganese(IV) at a similar rate, establishing a redox steady-state equilibrium under turnover conditions. Hypochlorous acid (HOCl) produced during turnover was found to rapidly and reversibly react with manganese(III)TDMImP to give dioxoMn(V)TDMImP and chloride ion. The measured equilibrium constant for this reaction (Keq = 2.2 at pH 5.1) afforded a value for the oxoMn(V)/Mn(III) redox couple under catalytic conditions (E′ = 1.35 V vs NHE). In subsequent processes, chlorine dioxide reacts with both oxomanganese(V) and oxomanganese(IV)TDMImP to afford chlorate ion. Kinetic simulations of the proposed mechanism using experimentally measured rate constants were in agreement with observed chlorine dioxide growth and decay curves, measured chlorate yields, and the oxoMn(IV)/Mn(III) redox potential (1.03 V vs NHE). This acid-free catalysis could form the basis for a new process to make ClO2.
- Umile, Thomas P.,Wang, Dong,Groves, John T.
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- Autocatalysis and self-inhibition: Coupled kinetic phenomena in the chlorite-tetrathionate reaction
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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
- Horvath, Attila K.,Nagypal, Istvan,Peintler, Gabor,Epstein, Irving R.
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- Kinetics and Mechanism of the Reaction between Chlorite Ion and Hypochlorous Acid
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The reaction between ClO2- and HOCl has been studied by spectrophotometrically monitoring the production of ClO2 at pH 5-6.In excess ClO2-, the reaction is first rder in ClO2-, HOCl, and H+, and the stoichiometry is given by HOCl + 2 ClO2- + H+ -> 2 ClO2 + Cl- + H2O.In excess HOCl and at higher pH's, ClO3- is produced, and the order of the reaction is between 1 and 2 for HOCl and between 0 and 1 for H+.By combining computer simulation and least-squares analysis, we obtain a mechanism in which the reaction 2 HOCl + ClO2- -> ClO3- + Cl2 + H2O (k=(2.1+/-0.1) x 10-3 M-2 s-1) plays a key role in explaining the behavior at high /->.
- Peintler, Gabor,Nagypal, Istvan,Epstein, Irving R.
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- Kinetics and Mechanism of the Reaction between Chlorine(III) and Bromide Ion
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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.
- Valdes-Aguilera, Oscar,Boyd, Donald W.,Epstein, Irving R.,Kustin, Kenneth
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- Effect of chloride ion on the kinetics and mechanism of the reaction between chlorite ion and hypochlorous acid
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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.
- Kormanyos, Balazs,Nagypal, Istvan,Peintler, Gabor,Horvath, Attila K.
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- A kinetic study on reactions of OBrO with NO, OClO, and ClO at 298 K
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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.
- Li, Zhuangjie,Tao, Zhining
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- Kinetics and Mechanism of the Reaction between Chlorine(III) and Molecular Bromine
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Reaction between chlorine(III) and bromine results in the oxidation of chlorine(III) to chlorine dioxide according to 2ClO2- (or 2HClO2) + Br2 -> 2ClO2 + 2Br- (+ 2H+) (reaction A).The kinetics of reaction A were studied by stopped-flow spectrophotometry in the range 0.58-4.23, leading to a proposed mechanism in which the rate-determining step is BrClO2 + ClO2- (or HClO2) -> 2ClO2 + Br- (+ H+) (reaction B).The rate data obtained at 25 deg C and ionic strength 0.66 M yield the rate constant of reaction B, kB = (2.94 +/- 0.25) * 103 M-1 s-1, and the acidity constant of the intermediate BrClO2H+, Ka = (1.23 +/-0.02) * 10-2M.At pH 7.41 bromine is present as BrOH and Cl(III) as ClO2-.Consequently the rate constant for the reaction between BrOH and ClO2-, 20.6 M-1 s-1, indicates that BrOH is less reactive than Br2 toward Cl(III).Formation of the intermediate is a complex process involving attack by chlorine(III) on molecular bromine followed by electron transfer and leaving of bromide ion.
- Valdes-Aguilera, Oscar,Boyd, Donald W.,Epstein, Irving R.,Kustin, Kenneth
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- Mechanistic study of a manganese porphyrin catalyst for on-demand production of chlorine dioxide in water
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A water-soluble manganese porphyrin complex was examined for the catalytic formation of chlorine dioxide from chlorite under ambient temperature at pH 5.00 and 6.90. Quantitative kinetic modeling allowed for the deduction of a mechanism that accounts for all experimental observations. Catalysis is initiated via an OAT (Oxygen Atom Transfer) reaction resulting in formation of a putative manganese(V) oxo species, which undergoes ET (Electron Transfer) with chlorite to form chlorine dioxide. As chlorine dioxide accumulates in solution, chlorite consumption slows down and ClO2 reaches a maximum as the system reaches equilibrium. In phosphate buffer at pH 6.90, manganese(IV) oxo accumulates and its reaction with ClO2 gives ClO3-. However, at pH 5.00 acetate buffer proton coupled electron transfer (PCET) from chlorite to manganese(IV) oxo is fast and irreversible leading to chlorate formation only via the putative manganese(V) oxo species. These differences underscore how PCET rates affect reaction pathways and mechanism. The ClO2 product can be collected from the aqueous reaction mixture via purging with an inert gas, allowing for the preparation of chlorine dioxide on-demand.
- Hicks, Scott D.,Xiong, Silei,Bougher, Curt J.,Medvedev, Grigori A.,Caruthers, James,Abu-Omar, Mahdi M.
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- Chlorite dismutation to chlorine dioxide catalyzed by a water-soluble manganese porphyrin
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Chloride oxyanions are of interest because of their use as disinfectants and concerns over their accumulation in the environment. A water-soluble manganese porphyrin catalyzes the dismutation of chlorite (ClO2 -) to chlorine dioxide
- Hicks, Scott D.,Petersen, Jennifer L.,Bougher, Curt J.,Abu-Omar, Mahdi M.
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- Oxidation of Chlorine(III) by Hypobromous Acid: Kinetics and Mechanism
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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.
- Toth, Zsuzsanna,Fabian, Istvan
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- Ultraviolet Absorption Cross Sections of Cl2O2 between 210 and 410 nm
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The ultraviolet and infrared absorption cross of Cl2O2 have been measured.The transient Cl2O2 molecule was produced by using the gas-phase reaction ClO + ClO + M -> Cl2O2 + M.Three independent ClO radical source reactions were used in this study: Cl + O3, Cl + Cl2O, and Cl + OClO.The Cl2O2 UV absorption spectrum was recorded over the range 200-450 nm with a diode array spectrometer over the temperature range 205-250 K.The Cl2O2 infrared absorption spectrum was recorded with a high-resolution Fourier transform spectrometer over the range 500-2000 1/cm.Both spectrometers were optically coupled to a fast flow multipass absorption cell.The UV absorption spectrum of Cl2O2 is a structureless continuum with a peak at 245 nm.The measurable absorption extends out to 410 nm.The UV absorption cross section at the peak of the spectrum, 245 nm, was measured to be (6.5+0.8-0.5) X 1E-18 cm2.Infrared absorption features centered at 560, 653, and 750 1/cm have been assigned to the Cl2O2 molecule.The present results are compared with other reported UV and IR measurements and the sources of discrepancies are discussed.The role of Cl2O2 in atmospheric chemistry and in particular the Antarctic ozone hole are discussed.
- Burkholder, James B.,Orlando, John J.,Howard, Carleton J.
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- Oxyhalogen-sulfur chemistry: Oxidation of taurine by chlorite in acidic medium
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The reaction between chlorite and the aminosulfonic acid, taurine, has been studied in neutral to acidic pH. The stoichiometry of the reaction was deduced as 3ClO2- + H2NCH2CH2SO3H + 3H+ a?? Cl(H)NCH2CH2SO3H + 2ClO2 + 2H2O. The formation of chlorotaurine is rapid and is followed by a slower accumulation of chlorine dioxide. The chlorotaurine disproportionates at low pH to give dichlorotaurine and taurine. There is no appreciable reaction between chlorine dioxide and any of the amine species in solution. The reaction is characterized by an induction period during which the reactive species HOCl and H(OH)NCH2CH2SO3H are formed. This is followed by the autocatalytic production of chlorotaurine and chlorine dioxide. The autocatalysis is mediated through the formation of the intermediate Cl2O2, which is typical of the reactions of chlorite. One notable result obtained in this study was that the C-S bond in taurine does not cleave even when subjected to a strong oxidizing agent, HOCl.
- Chinake, Cordelia R.,Simoyi, Reuben H.
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- Antioxidant chemistry: Oxidation of L-cysteine and its metabolites by chlorite and chlorine dioxide
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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.
- Darkwa, James,Olojo, Rotimi,Chikwana, Edward,Simoyi, Reuben H.
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- Infrared Spectroscopic and ab Initio Study of HOOClO2
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HOOClO2 was produced by addition of hydrogen atoms to a mixture of O2 and OClO on the surface of growing argon matrixes at 17 K. The compound was identified by infrared spectroscopy utilizing the H to D and 18O2 and 16,18O2 spectral shifts. The matrices were irradiated with the full radiation from a 300-W Xe lamp. HOOClO2 was eliminated by the irradiation, but we were unable to identify the photodecomposition product. Ab initio calculations show that HOO binds to OClO with a bond strength intermediate between a van der Waals interaction and a covalent bond.
- Svensson, Thomas,Nelander, Bengt,Bernhardsson, Anders,Karlstr?m, Gunnar
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- Three autocatalysts and self-inhibition in a single reaction: A detailed mechanism of the chlorite-tetrathionate reaction
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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.
- Horvath, Attila K.,Nagypal, Istvan,Epstein, Irving R.
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- Studies of reactions of importance in the stratosphere. III. Rate constant and products of the reaction between ClO and HO2 radicals at 298 K
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The rate constant for the radical-radical reaction ClO+HO2HOCl+O2 was measured at 298 K by the discharge flow technique using mass spectrometry for detection of the HOCl product m/e=52.The ClO radical was generated by reacting ozone with chlorine atoms produced in a microwave discharge, and the concentration of ClO determined by measuring the decrease in ion current due to Cl2+ at m/e=70 upon activation of the discharge.This method was found to be in agreement with a nitric oxide titration of ClO and with the stochiometric conversion of ClO to NO2 by reactionwith a large excess of NO followed by absolute calibration for NO2 at m/e=46.Two reactions were used to generate the hydroperoxyl radical: (1) H+O2+M->HO2+M, and (2) Cl+H2O2->HCl+HO2.The rate constant k1 was found to be independent of pressure over the range 2-6 Torr, the result being k1=(4.5+/-0.9)*10-12 cm3molecule-1s-1, where the error includes our estimate of the maximum possible systematic error.An upper limit of 2percent for the branching ratio to the alternative products of this reaction, HCl+O3, was established by attempting to detect ozone as a reaction product.For these measurements the reactions Cl+ClOCl->Cl2+ClO and Cl+OClO->2ClO were used to generate the ClO radical in the absence of ozone.No other reaction products could be identified in the mass spectrum.
- Leck, Thomas J.,Cook, Jac-E L.,Birks, John W.
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- Quantum yield for ClOO formation following photolysis of aqueous OClO
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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.
- Thomsen,Reid,Keiding
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- Time-resolved infrared absorption studies of the solvent-dependent vibrational relaxation dynamics of chlorine dioxide
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We report a series of time-resolved infrared absorption studies on chlorine dioxide (OClO) dissolved in H2O, D2O, and acetonitrile. Following the photoexcitation at 401 nm, the evolution in optical density for frequencies corresponding to asymmetric stretch of OClO is measured with a time resolution of 120±50 fs. The experimentally determined optical-density evolution is compared with theoretical models of OClO vibrational relaxation derived from collisional models as well as classical molecular-dynamics (MD) studies. The vibrational relaxation rates in D2O are reduced by a factor of 3 relative to H2O consistent with the predictions of MD. This difference reflects modification of the frequency-dependent solvent-solute coupling accompanying isotopic substitution of the solvent. Also, the geminate-recombination quantum yield for the primary photofragments resulting in the reformation of ground-state OClO is reduced in D2O relative to H2O. It is proposed that this reduction reflects enhancement of the dissociation rate accompanying vibrational excitation along the asymmetric-stretch coordinate. In contrast to H2O and D2O, the vibrational-relaxation dynamics in acetonitrile are not well described by the theoretical models. Reproduction of the optical-density evolution in acetonitrile requires significant modification of the frequency-dependent solvent-solute coupling derived from MD. It is proposed that this modification reflects vibrational-energy transfer from the asymmetric stretch of OClO to the methyl rock of acetonitrile. In total, the results presented here provide a detailed description of the solvent-dependent geminate-recombination and vibrational-relaxation dynamics of OClO in solution.
- Bolinger, Joshua C.,Bixby, Teresa J.,Reid, Philip J.
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- CARS detection of ClO2
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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
- Zhang,Aker
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- Rate constant measurement for the reaction of OClO with NO at 220-367 K
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The reaction kinetics for the reaction OClO + NO → ClO + NO2 at 220-367 K was studied using fast flow coupled with MS. Under pseudo-first-order condition, the rate constant for the reaction of OClO with NO was in contrast to the positive temper
- Li,Wuebbles,Pylawka
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- Kinetics and mechanism of the initial phase of the bromine - chlorite ion reaction in aqueous solution
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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.
- Toth, Zsuzsanna,Fabian, Istvan
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- UV absorption spectrum of the ClO dimer (Cl2O2) between 200 and 420 nm
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The UV photolysis of Cl2O2 (dichlorine peroxide) is a key step in the catalytic destruction of polar stratospheric ozone. In this study, the gas-phase UV absorption spectrum of Cl2O2 was measured using diode arr
- Papanastasiou, Dimitrios K.,Papadimitriou, Vassileios C.,Fahey, David W.,Burkholder, James B.
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- General-acid-catalyzed reactions of hypochlorous acid and acetyl hypochlorite with chlorite ion
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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.
- Jia, Zhongjiang,Margerum, Dale W.,Francisco, Joseph S.
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- AQUEOUS COMPOSITION AND METHOD OF PRODUCING CHLORINE DIOXIDE USING AQUEOUS COMPOSITION
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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.
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- Reactions of aquacobalamin and cob(II)alamin with chlorite and chlorine dioxide
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Reactions of aquacobalamin (H2O–Cbl(III)) and its one-electron reduced form (cob(II)alamin, Cbl(II)) with chlorite (ClO2 ?) and chlorine dioxide (ClO2 ?) were studied by conventional and stopped-flow UV–Vis spectroscopies and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). ClO2 ? does not react with H2O–Cbl(III), but oxidizes Cbl(II) to H2O–Cbl(III) as a major product and corrin-modified species as minor products. The proposed mechanism of chlorite reduction involves formation of OCl? that modifies the corrin ring during the course of reaction with Cbl(II). H2O–Cbl(III) undergoes relatively slow destruction by ClO2 ? via transient formation of oxygenated species, whereas reaction between Cbl(II) and ClO2 ? proceeds extremely rapidly and leads to the oxidation of the Co(II)-center.
- Dereven’kov, Ilia A.,Shpagilev, Nikita I.,Valkai, László,Salnikov, Denis S.,Horváth, Attila K.,Makarov, Sergei V.
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p. 453 - 459
(2017/06/05)
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- DUAL BIOCIDE GENERATOR
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Methods and apparatus for generation of dual biocides are provided. The electrolytic generation of chlorine as a biocide is employed for further generation of additional biocides within a single system or generator, including bromine, iodine, chlorine dioxide, fluorine, or chloramines from their respective salts and/or precursors. A single on-site generating system produces a combination of biocides for applications of use providing cost, safety and efficacy improvements. Methods of using the disinfecting biocides provide a synergistic effect through simultaneous or sequential applications.
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Paragraph 0100; 0101
(2016/02/21)
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- Kinetics and Mechanism of the Chlorite-Periodate System: Formation of a Short-Lived Key Intermediate OClOIO3 and Its Subsequent Reactions
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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
- Baranyi, Nóra,Cseko, Gy?rgy,Valkai, László,Xu, Li,Horváth, Attila K.
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p. 2436 - 2440
(2016/03/19)
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- Chemoselective catalytic oxidation of 1,2-diols to α-hydroxy acids controlled by TEMPO-ClO2 charge-transfer complex
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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.
- Furukawa, Keisuke,Shibuya, Masatoshi,Yamamoto, Yoshihiko
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supporting information
p. 2282 - 2285
(2015/05/13)
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- NOVEL REDUCING AGENTS FOR PRODUCING CHLORINE DIOXIDE
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Methods of producing chlorine dioxide including providing an acid, a chlorate salt and an organic water treatment additive that can form a reducing agent in situ, mixing the acid, the chlorate salt and the organic water treatment additive, and reacting th
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- Photoreduction of Pt(IV) halo-hydroxo complexes: Possible hypohalous acid elimination
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Concentrated hydrogen peroxide addition to trans-Pt(PEt3) 2Cl(R) [1 (R = 9-phenanthryl), 2 (R = 4-trifluoromethylphenyl)] yields hydroxo-hydroperoxo complexes trans-Pt(PEt3) 2(Cl)(OOH)(OH)(R) [5 (R = 9-phenanthryl), 4 (R = 4- trifluoromethylphenyl)], where the hydroperoxo ligand is trans to R. Complex 5 is unstable and reacts with solvent CH2Cl2 to give trans,cis-Pt(PEt3)2(Cl)2(OH)(9-phenanthryl) (3). Treatment of 4 with HCl yields analogous trans,cis-Pt(PEt3) 2(Cl)2(OH)(4-trifluoromethylphenyl) (6) and HBr gives trans-Pt(PEt3)2(Br)(Cl)(OH)(4-trifluoromethylphenyl) (7), where the Br and 4-trifluoromethylphenyl ligands are trans. Photolysis of 3 or 6 at 313 or 380 nm causes reduction to trans-Pt(PEt3)2Cl(R) (1 or 2, respectively). Expected coproduct HOCl is not detected, but authentic solutions of HOCl are shown to decompose under the reaction conditions. Chlorobenzene and other unidentified products that oxidize PPh3 to OPPh3 are detected in photolyzed benzene solutions. Photolysis of 3 or 6 in the presence of 2,3-dimethyl-2-butene (TME) yields the chlorohydrin (2-chloro-2,3-dimethyl-3-butanol), 3-chloro-2,3-dimethyl-1-butene, and acetone, all expected products from HOCl trapping, but additional oxidation products are also observed. Photolysis of mixed chloro-bromo complex 7 with TME yields the bromohydrin (2-bromo-2,3-dimethyl-3-butanol) and 2, consistent with cis-elimination of HOBr. Computational results (TDDFT and DFT) and photochemistry of related complexes suggest a dissociative triplet excited state reaction pathway and that HOCl elimination may occur by an incipient hydroxo radical abstraction of an adjacent halogen atom, but a pathway involving hydroxo radical reaction with solvent or TME to generate a carbon-based radical followed by halogen abstraction from Pt cannot be eliminated.
- Wickramasinghe, Lasantha A.,Sharp, Paul R.
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p. 1430 - 1442
(2014/03/21)
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- METHOD FOR PRODUCING AN AQUEOUS STABLE CHLORINE DIOXIDE SOLUTION
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The invention relates to a method for producing an ultrapure, aqueous, long-term- and storage-stable, and thus transportable, chlorine dioxide solution, comprising the steps of: providing chlorite, providing peroxodisulfate, and combining chlorite and peroxodisulfate in an aqueous system and in a molar ratio of peroxodisulfate to chlorite [S2O82?]/[ClO2?] of greater than 1, forming the aqueous chlorine dioxide solution, wherein no additional buffer is added to produce the aqueous chlorine dioxide solution. The invention further relates to a corresponding chlorine dioxide solution, to the use of said chlorine dioxide solution, and to a device for producing the chlorine dioxide solution.
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(2013/11/06)
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- A much-needed mechanism and reaction rate for the oxidation of phenols with ClO2: A joint experimental and computational study
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The oxidation of phenols with chlorine dioxide, a powerful means to eliminate phenol pollutants from drinking water, is explored. Kinetic experiments reveal that 2,4,6-trichlorophenol exhibits a lower oxidation rate than other phenols because the chlorine atoms (σ≤0.22) at ortho and para-positions decrease the benzene's electron density, in agreement with the Hammett plot. The oxidation of phenol was found to be second order with respect to phenol and first order with respect to ClO2 and a possible mechanism is proposed. The phenol/ClO2 oxidation was found to be pH-dependent since the reaction rate constant increases with increasing pH. The oxidation rate was also significantly enhanced with an increasing methanol ratio in water. The oxidation products, such as benzoquinones, were analysed and confirmed by liquid chromatography and gas chromatography-mass spectrometry. Density functional theory computations at both the B3LYP/6-311+G(d,p) and M06-2X.6-311+G(d,p) levels with the SCRF-PCM solvation model (i.e. with water) further supported the proposed mechanisms in which activation barriers predicted the right reactivity trend as shown by the kinetic experiments. CSIRO 2013.
- Aguilar, Carlos Alberto Huerta,Narayanan, Jayanthi,Manoharan, Mariappan,Singh, Narinder,Thangarasu, Pandiyan
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p. 814 - 824
(2013/08/23)
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- CHLORINE DIOXIDE SOLUTION COMPOSITION
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There are provided a chlorine dioxide solution composition whose solute includes dissolved chlorine dioxide and chlorite; and a solution composition encapsulating body including a glass vessel or enameled vessel and the chlorine dioxide solution composition hermetically sealed therein.
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- Composition and method for enhanced sanitation and oxidation of aqueous systems
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This invention relates to a method for enhanced sanitation and oxidation of aqueous solutions at aquatic facilities. The method provides a means for the in-situ generation of chlorine dioxide from dilute solutions of chlorite anions at near neutral pH, and enhanced inactivation rates of microbiological organisms including cryptosporidium.
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- MULTI-PART DISINFECTANT
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Disclosed is a multi-part disinfectant composition, wherein the parts thereof are solid and are packaged separately prior to use, and wherein the separately-packaged parts, when combined in the presence of water or an aqueous solution, react to form chlor
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- THERAPEUTIC AGENT FOR INFECTIOUS SKIN OR MUCOSAL DISEASE
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A therapeutic agent for infectious skin and mucosal diseases to be applied to an infected area for ameliorating a symptom of the infected area caused by infection with a pathogenic microorganism includes: a chlorine dioxide solution including a dissolved
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- ENERGY-ACTIVATED COMPOSITIONS FOR CONTROLLED SUSTAINED RELEASE OF A GAS
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A composition for energy-controlled generation and release of at least one gas, which includes an energy-activated catalyst capable of being activated by electromagnetic energy, and a solid or a liquid containing anions capable of being oxidized by the activated catalyst or reacted with species generated during activation of the catalyst to generate at least one gas. The composition, when exposed to electromagnetic energy, is capable of generating and releasing the gas after activation of the catalyst and oxidation or reaction of the anions.
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Page/Page column 12; 9/13; 10/13; 11/13
(2008/06/13)
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- A METHOD OF PRODUCING STABLE OXY-CHLORO ACID
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The invention is a method of producing stable chlorous acid for use as a cleaning agent and biocidal composition. The method passes a salt of an oxy-chloro acid over a resin to allow for an ion exchange that produced the oxy-chloro acid. The invention all
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Page/Page column 7
(2008/12/07)
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- Portable bio-chemical decontaminant system and method of using the same
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The present invention relates to a portable bio-chemical decontaminant system and methods of using the same. Specifically, the present invention provides a portable bio-chemical decontaminant system that is rapidly effective across a broad range of chemic
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Page/Page column 10
(2008/12/07)
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- Technique for treatment and prevention of fungal diseases in field-grown grains and legumes by application of acid-activated sodium chlorite solution
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A technique for reducing fungal disease in growing grain-producing grasses and growing legume plants involves the generation of chlorine dioxide gas by dissolution of sodium chlorite with an activating acid in an aqueous solution, followed by foliar application of the gas to grasses or legume plants growing in fields. The most preferred acid solution contains urea sulphuric acid (monocarbamide dihydrogen sulphate).
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Page/Page column 2
(2009/01/20)
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- Ultraviolet absorption spectrum of chlorine peroxide, ClOOCl
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The photolysis of chlorine peroxide (ClOOCl) is understood to be a key step in the destruction of polar stratospheric ozone. This study generated and purified ClOOCl in a novel fashion, which resulted in spectra with low impurity levels and high peak abso
- Pope, Francis D.,Hansen, Jaron C.,Bayes, Kyle D.,Friedl, Randall R.,Sander, Stanley P.
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p. 4322 - 4332
(2008/10/09)
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- TECHNIQUE FOR TREATMENT AND PREVENTION OF FUNGAL DISEASES IN GROWING GRAPES BY APPLICATION OF A SODIUM CHLORITE, UREA SULFURIC ACID SOLUTION
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A technique for reducing fungal disease in grape vineyards involves the generation of chlorine dioxide gas by dissolution of sodium chlorite with a urea sulphuric acid (monocarbamide dihydrogen sulphate) activating acid in water, followed by foliar applic
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Page/Page column 3
(2008/06/13)
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- CONFIGURATIONS FOR CHLORINE DIOXIDE PRODUCTION
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Methods and compositions to produce chlorine dioxide by reacting one or more reactants under the presence of polarized ultraviolet radiation, an electromagnetic field (EMF), successive chambers, and coiled configurations are disclosed. Polarized ultraviol
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Page/Page column 12-14
(2008/06/13)
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- Plant life control composition
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Plant life control composition including stabilized chlorine dioxide. A method of controlling plant life or removing contaminants from plant life comprising contacting the plant life with a composition including stabilized chlorine dioxide. The plant life
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Page/Page column 2
(2008/06/13)
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- Simple apparatus for producing chlorine dioxide gas
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The present invention relates to a simple apparatus for producing chlorine dioxide gas, and more specifically, a simple apparatus for producing chlorine dioxide gas in which a sand or silica gel layer, a chlorine dioxide producing layer and, if necessary,
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Page/Page column 4
(2008/06/13)
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- Method and apparatus for microbial decontamination
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A process and apparatus is provided for generating chlorine dioxide gas for the fumigation of enclosed spaces that includes adding reactants for generation of chlorine dioxide by dropwise addition to an aqueous reaction medium in a sealed reaction chamber
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Page/Page column 5
(2008/06/13)
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- Reactions of POxCly-ions with H and H 2 from 298 to 500 K
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Rate constants and product branching ratios for POxCl y-ions reacting with H and H2 were measured in a selected ion flow tube (SIFT) from 298 to 500 K. PO2Cl-, PO2Cl2-, POCl2-, and POCl3- were all unreactive with H2, having a rate constant with an upper limit of -12 cm 3 s-1. PC2Cl2- did not react with H atoms either, having a similar rate constant limit of -12 cm3 s-1. The rate constants for PO 2Cl-, POCl2-, and POCl 3- reacting with H showed no temperature dependence over the limited range of 298-500 K and were approximately 10-20% of the collision rate constant Cl abstraction by H to form HCl was the predominant product channel for PO2Cl-, POCl2-, and POCl3-, with a small amount of Cl- observed from POCl2- + H. Reactions of O2 and O 3 with the POCl- products ions from the reaction of POCl2- + H were observed to yield predominantly PO 3- and PO2-, respectively. POCl - reacted with C2 and O3 with rate constants of 8.9 ± 1.1 × 10-11 and 5.2 ± 3.3 × 10 -10 cm3 s-1, respectively. No associative electron detachment in the reactions with H atoms was observed with any of the reactant ions; however, detachment was observed with a PO- secondary product ion at high H atom concentrations. Results of new G3 theoretical calculations of optimized geometries and energies for the products observed are discussed.
- Midey, Anthony J.,Miller, Thomas M.,Morris, Robert A.,Viggiano
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p. 2559 - 2563
(2008/03/12)
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- Kinetics and mechanisms of bromine chloride reactions with bromite and chlorite ions
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Chloride ion catalyzes the reactions of HOBr with bromite and chlorite ions in phosphate buffer (p[H+] 5 to 7). Bromine chloride is generated in situ in small equilibrium concentrations by the addition of excess Cl - to HOBr. In the BrCl/ClO2- reaction, where ClO2- is in excess, a first-order rate of formation of ClO2 is observed that depends on the HOBr concentration. The rate dependencies on ClO2-, Cl-, H+, and buffer concentrations are determined. In the BrCl/BrO2- reaction where BrCl is in pre-equilibrium with the excess species, HOBr, the loss of absorbance due to BrO2- is followed. The dependencies on Cl-, HOBr, H+, and HPO4 2- concentrations are determined for the BrCl/BrO2 - reaction. In the proposed mechanisms, the BrCl/ClO2 - and BrCl/BrO2- reactions proceed by Br + transfer to form steady-state levels of BrOClO and BrOBrO, respectively. The rate constant for the BrCl/ClO2- reaction (k2Cl) is 5.2 x 106 M-1 s-1 and for the BrCl/BrO2- reaction (k 2Br) is 1.9 × 105 M-1 s -1. In the BrCl/ClO2- case, BrOClO reacts with ClO2- to form two ClO2 radicals and Br -. However, the hydrolysis of BrOBrO in the BrCl/ BrO 2- reaction leads to the formation of BrO3 - and Br-.
- Odeh, Ihab N.,Nicoson, Jeffrey S.,Huff Hartz, Kara E.,Margerum, Dale W.
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p. 7412 - 7420
(2008/10/09)
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- Oxidative transformation of 1,3-dioxacycloalkanes induced by chlorine dioxide
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The products and kinetic regularities of the reactions of 1,3-dioxacycloalkanes with chlorine dioxide were studied. The effects of the nature of solvent and the temperature on the reaction rate were considered and the activation parameters were determined.
- Abdrakhmanova,Kabal'nova,Rol'nik,Yagafarova,Shereshovets
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p. 1755 - 1760
(2007/10/03)
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- Reaction kinetics of PO2Cl-, PO2Cl 2-, POCl2- and POCl3 - with O2 and O3 from 163 to 400 K
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Rate constants and product ion branching fractions for the gas-phase reactions of O2 and O3 with the anions (a) PO 2Cl-, (b) POCl3-, (c) POCl 2-, and (d) PO2Cl2- were measured in a selected-ion flow tube (SIFT). The kinetics were measured at temperatures of 163-400 K and a He pressure of 0.4 Torr. Only PO 2Cl- reacts with O2 to a measurable extent, having k(163-400 K) = 1.1 × 10-8(T/K)-1.0 cm 3 molecule-1 s-1, while O3 reacts with all of the anions except PO2Cl2-. The fitted rate constant expressions for the O3 reaction with anions a-c are as follows: ka(163-400 K) = 3.5 × 10-6(T/K) -1.6, kb(163-400 K) = 4.0 × 10 -7(T/K)-1.2, and kc(163-400 K) = 3.7 × 10-7(T/K)-1.4 cm3 molecule-1 s -1. Calculations were performed at the G3 level of theory to obtain optimized geometries, energies, and electron affinities (EAs) of the reactant and product species, as well as to determine the reaction thermochemistry to help understand the experimental results. The POxCly - anions that have lower electron binding energies (eBE) and higher spin multiplicities are more reactive. The doublets are more labile than the singlets. How the extra electron density is distributed in the anion does not predict the observed reactivity of the ion. The reactions of PO 2Cl- with O2 and O3 yield predominantly PO3- and PO4-. The reaction of POCl2- with O3 yields mostly Cl- and PO2Cl2-, while the POCl 3- reaction with O3 yields mostly O 3- and PO2Cl2-.
- Fernandez, Abel I.,Midey, Anthony J.,Miller, Thomas M.,Viggiano
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p. 9120 - 9125
(2008/10/09)
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- Kinetics and mechanisms of the reactions of hypochlorous acid, chlorine, and chlorine monoxide with bromite ion
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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.
- Nicoson, Jeffrey S.,Perrone, Thomas F.,Huff Hartz, Kara E.,Wang, Lu,Margerum, Dale W.
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p. 5818 - 5824
(2008/10/08)
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- Kinetics and mechanisms of aqueous chlorine reactions with chlorite ion in the presence of chloride ion and acetic acid/acetate buffer
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The kinetics and mechanism of the reaction between Cl2 and CIO2- are studied in acetate buffer by stopped-flow spectrometric observation of CIO2 formation. The reaction is first-order in [CI2] and [CIO2-], with a rate constant of k1 = (5.7 ± 0.2) × 105 M-1 s-1 at 25.0 °C. Nucleophilic attack by CIO2- on CI2, with CI+ transfer to form CIOCIO and CI-, is proposed as the rate-determining step. A possible two-step electron-transfer mechanism for CI2 and CIO2- is refuted by the lack of CIO2 suppression. The yield Of CIO2 is much less than 100%, due to the rapid reactions of the metastable CIOCIO intermediate via two competing pathways. In one path, CIOCIO reacts with CIO2- to form 2CIO2 and CI-, while in the other path it hydrolyzes to give CIO3- and CI-. The observed rate constant also is affected by acetate-assisted hydrolysis of CI2. The rate of CI2 loss is suppressed as the concentration of CI- increases, due to the formation of CI3-. In excess CIO2-, a much slower formation of CIO2 is observed after the initial CI2 reaction, due to the presence of HOCI, which reacts with H+ and CI- to re-form steady-state levels of CI2.
- Nicoson, Jeffrey S.,Margerum, Dale W.
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p. 342 - 347
(2008/10/08)
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- Resonance Raman intensity analysis of chlorine dioxide dissolved in chloroform: The role of nonpolar solvation
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An absolute resonance Raman intensity analysis (RRIA) of OClO dissolved in chloroform is presented. It is shown that solvent invariance is consistent with nonpolar or mechanical solvation dynamics dominating the solvent response to OClO photoexcitation. F
- Foster,Barham,Reid
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p. 8492 - 8504
(2007/10/03)
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- The catalytic behaviour of NiFe2-xCrxO4 (0.0≤×≤ 2.0) during the thermal decomposition of ammonium perchlorate, polystyrene and their composite propellants
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NiFe2O4, NiFeCrO4 and NiCr2O4 catalysts have been prepared by solid state reaction and characterised by using chemical analysis and X-ray diffraction techniques. Electrical conductivity and thermoelectric power measurements have shown that the catalysts are p-type semiconductors. The thermal decomposition of ammonium perchlorate, polystyrene and a composite propellant of ammonium perchlorate and polystyrene has been studied in the presence of these catalysts using thermogravimetric analyser. The effectiveness of the catalysts during the decomposition of ammonium perchlorate (AP), polystyrene (PS) and a composite propellant of AP+PS has the following order respectively: NiCr2O4 > NiFeCrO4 > NiFe2O4 NiFeCrO4 > NiCr2O4 > NiFe2O4 and NiFeCrO4 > NiFe2O4.
- Dubey,Singh,Srivastava,Ojha
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p. 841 - 847
(2007/10/03)
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- Interaction of ozone with HCl sorbed on a thin layer of ice at 77 K
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A heterogeneous reaction of ozone with the ice-HCl(ads) system is studied over the temperature range 77-223 K. The process occurs extremely rapidly with the formation of a red condensate, which is supposedly (from the IR absorption spectroscopy data) composed of Cl2O and ClO2. At 77 K, the reaction supposedly proceeds according to the tunneling mechanism.
- Yagodovskaya,Savilov,Zosimov,Lunin
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p. 1028 - 1030
(2007/10/03)
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- Unexpected phenomena in the mercury(II)-chlorite ion system: Formation and kinetic role of the HgClO2+ complex
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On the basis of time-resolved spectrophotometric measurements, the formation of a novel chlorito complex, HgClO2+, was confirmed under acidic condition in the mercury(II)-chlorite ion system. The complex formation occurs within the dead time of the stopped-flow instrument applied (τd approximately 1 ms). The stability constant of HgClO2+ was determined from the initial part of the kinetic traces recorded at the characteristic 325 nm absorbance maximum of the complex: K = 41.7±1.9 M-1, ε325 = 727±24 M-1 cm-1 (I = 1.0 M (NaClO4), 25.0 °C). An intense formation of chlorine dioxide was observed which is due to mercury(II)-catalyzed decomposition of chlorite ion. At longer reaction times, when most of the chlorite ion is consumed, the concentration of chlorine dioxide abruptly drops to its final value. This unique feature of the reaction is attributed to an autocatalytic redox cycle which is initiated by an electron transfer step between the coordinated chlorite ion and chlorine dioxide. The proposed mechanism postulates the formation of a Cl(II) intermediate which rapidly oxidizes both ClO2- and ClO2.
- Fabian, Istvan,Szuics, Dora,Gordon, Gilbert
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p. 8045 - 8049
(2007/10/03)
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