- Lysosome-targeted two-photon fluorescent probe for detection of hypobromous acid in vitro and in vivo
-
It is found that hypobromous acid (HOBr) can affect the activity of type IV collagen. Herein, we synthesized a lysosome-targeted fluorescence probe NA-lyso based on Suzuki coupling reaction with naphthalimide as a fluorescent group. HOBr can oxidize the amino group and methylthio group, which increased the degree of conjugation of the probe, thereby affecting its optical properties. Accordingly, it can establish a method for the specific detection of HOBr. NA-lyso has the properties including fast response, high fluorescence quantum yield (Φ = 59.17%), high selectivity, low cytotoxicity and good membrane-permeability. The probe can locate to lysosome of cells. The potential of the probe as biosensor for HOBr was demonstrated by imaging of exogenous and endogenous HOBr in living cells and in mice. In consequence, NA-lyso is expected to be a powerful tool to detect HOBr in complex biosystem and provides a means of exploring physiological functions associated with HOBr in living organisms.
- Ma, Chen,Ma, Minrui,Zhang, Yida,Zhu, Xinyue,Zhou, Lin,Fang, Ran,Liu, Xiaoyan,Zhang, Haixia
-
-
- Cyclic Regulation of the Sulfilimine Bond in Peptides and NC1 Hexamers via the HOBr/H2Se Conjugated System
-
The sulfilimine bond (-S=N-), found in the collagen IV scaffold, significantly stabilizes the architecture via the formation of sulfilimine cross-links. However, precisely governing the formation and breakup process of the sulfilimine bond in living organisms for better life functions still remains a challenge. Hence, we established a new way to regulate the breaking and formation of the sulfilimine bond through hydrogen selenide (H2Se) and hypobromous acid (HOBr), which can be easily controlled at simulated physiological conditions. This novel strategy provides a circulation regulation system to modulate the sulfilimine bond in peptides and NC1 hexamers, which can offer a substantial system for further study of the physiological function of collagen IV.
- Luan, Dongrui,Gao, Xiaonan,Kong, Fanpeng,Song, Xiaoxiao,Zheng, Aishan,Liu, Xiaojun,Xu, Kehua,Tang, Bo
-
p. 9523 - 9528
(2018/07/05)
-
- Selective Monitoring and Imaging of Eosinophil Peroxidase Activity with a J-Aggregating Probe
-
The specific detection of eosinophil peroxidase (EPO) activity requires the difficult distinction between hypobromous acid generated by EPO and hypochlorous acid generated by other haloperoxidases. Here we report a fluorogenic probe that is halogenated with high kinetic selectivity (≥1200:1) for HOBr over HOCl. Heavy-atom effects do not quench the dibrominated product because of its self-assembly into emissive J-aggregates that provide a turn-on signal. Applications of this fluorogen to EPO activity assays, dipstick sensors, fluorescence imaging of EPO activity, assays of oxidative stress in cancer cells, and immune response detection in live mice are reported.
- Kim, Tae-Il,Hwang, Byunghee,Lee, Boeun,Bae, Jeehyeon,Kim, Youngmi
-
supporting information
p. 11771 - 11776
(2018/09/20)
-
- Characterisation of peroxidasin activity in isolated extracellular matrix and direct detection of hypobromous acid formation
-
Peroxidasin is a heme peroxidase that catalyses the oxidation of bromide by hydrogen peroxide to form an essential sulfilimine cross-link between methionine and hydroxylysine residues in collagen IV. We investigated cross-linking by peroxidasin embedded in extracellular matrix isolated from cultured epithelial cells and its sensitivity to alternative substrates and peroxidase inhibitors. Peroxidasin showed peroxidase activity as measured with hydrogen peroxide and Amplex red. Using a specific mass spectrometry assay that measures NADH bromohydrin, we showed definitively that the enzyme releases hypobromous acid (HOBr). Less than 1 μM of the added hydrogen peroxide was used by peroxidasin. The remainder was consumed by catalase activity that was associated with the matrix. Results from NADH bromohydrin measurements indicates that low micromolar HOBr generated by peroxidasin was sufficient for maximum sulfilimine cross-linking, whereas 100 μM reagent HOBr or taurine bromamine was less efficient. This implies selectivity for the enzymatic process. Physiological concentrations of thiocyanate and urate partially inhibited cross-link formation. 4-Aminobenzoic acid hydrazide, a commonly used myeloperoxidase inhibitor, also inhibited peroxidasin, whereas acetaminophen and a 2-thioxanthine were much less effective. In conclusion, HOBr is produced by peroxidasin in the extracellular matrix. It appears to be directed at the site of collagen IV sulfilimine formation but the released HOBr may also undergo other reactions.
- Bathish, Boushra,Turner, Rufus,Paumann-Page, Martina,Kettle, Anthony J.,Winterbourn, Christine C.
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p. 120 - 127
(2018/04/12)
-
- High-Quantum-Yield Mitochondria-Targeting Near-Infrared Fluorescent Probe for Imaging Native Hypobromous Acid in Living Cells and in Vivo
-
The discovery that hypobromous acid (HOBr) can regulate the activity of collagen IV has attracted great attention. However, HOBr as an important reactive small molecule has hardly ever been studied using a detection method suitable for organisms. Herein, a high-quantum-yield mitochondria-targeting near-infrared (NIR) fluorescent probe for HOBr, RhSN-mito, was designed. RhSN-mito was easily obtained by the Suzuki cross-coupling reaction. The test results show that RhSN-mito can rapidly respond to HOBr with ultrasensitivity and high selectivity. The achievement of ultrasensitivity lies in the high signal-to-noise ratio and the highest fluorescence quantum yield of the reaction product (φF = 0.68) in the near-infrared region, as far as we know. RhSN-mito is successfully applied to image native HOBr in mitochondria of HepG2 cells and zebrafish. Thus, RhSN-mito is a powerful tool for detecting native HOBr in vivo and is expected to provide a method to further study the physiological and pathological functions related to HOBr.
- Liu, Xiaojun,Zheng, Aishan,Luan, Dongrui,Wang, Xiaoting,Kong, Fanpeng,Tong, Lili,Xu, Kehua,Tang, Bo
-
p. 1787 - 1792
(2017/08/08)
-
- SELENO-COMPOUNDS AND THERAPEUTIC USES THEREOF
-
The present invention relates to compounds and compositions useful as antioxidants and in particular to selenium containing compounds of formula (I): wherein n is 1, 2, or 3; m is 2, 3, 4, or 5; and each R] is independently -(optionally substituted C 1 -C3 alkylene) p-OH, where p is 0 or 1, or a salt thereof. The invention also relates to the use of these seleno-compounds in the treatment of diseases or conditions associated with increased levels of oxidants produced by myeloperoxidase (MPO), such as for instance, atherosclerosis.
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Page/Page column 62-63
(2012/05/19)
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- Preventing protein oxidation with sugars: Scavenging of hypohalous acids by 5-selenopyranose and 4-selenofuranose derivatives
-
Heme peroxidases including myeloperoxidase (MPO) are released at sites of inflammation by activated leukocytes. MPO generates hypohalous acids (HOX, X = Cl, Br, SCN) from H2O2; these oxidants are bactericidal and are key components o
- Storkey, Corin,Pattison, David I.,White, Jonathan M.,Schiesser, Carl H.,Davies, Michael J.
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p. 2589 - 2599
(2013/01/15)
-
- Growth of spherulitic crystal patterns in a Belousov-Zhabotinski type reaction system
-
The growth of spherulitic crystal patterns in a Belousov-Zhabotinski (BZ) type reaction system by using acetyl acetone (AA)-succinic acid (SA) as dual organic substrates has been reported. The reaction system in the liquid phase has been found to show concentric ring-like wave patterns. A colloidal phase composed of numerous fine particles has also been observed during reaction. The solid phase nucleation has been found to occur in the colloidal phase, which leads to the formation of some stable nucleus centers. The solid phase nucleus has been found to grow in symmetric crystal patterns, with the progress of reaction, exhibiting spherulitic morphology. The possible growth behavior of spherulites has also been discussed. The spherulitic structure composed of fine crystal fibrils diverging from a common center have been observed by a scanning electron microscopy (SEM) technique. The polymorphic crystalline phase, found in spherulites has been supported by thermal characterization (TGA/DTA) and X-ray diffraction (XRD) patterns of crystal materials. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.
- Yadav, Narendra,Srivastava
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p. 1080 - 1087
(2011/07/08)
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- Methods and compositions for the reduction of pathogenic microorganisms from meat and poultry carcasses, trim and offal
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The invention includes a method of preparing hypochlorite-activated solutions of hypobromous acid and/or hypobromite ion. The method includes the steps of mixing a solution of a source of bromide ion with a solution of a source of hypochlorite ion to activate the bromide ion, allowing sufficient time to maximize the activation of the bromide ion, and storing the solution before use. The invention also includes a method of using the solution to wash meat and poultry carcasses, trim, and offal to reduce pathogenic microorganisms. The solutions may also be used to reduce pathogenic microorganisms in industrial cooling water and on food contact hard surfaces and equipment. The solutions may be stored for up to about three hours before use and are stable for that period of time.
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Page/Page column 5
(2011/09/14)
-
- Matrix-isolation infrared spectra of HOOBr and HOBrO produced upon VUV light irradiation of HBr/O2/Ne system
-
Vacuum ultraviolet (VUV) light photolysis of an HBr/O2 mixture in a Ne matrix has produced HO2Br isomers (HOOBr and HOBrO), which are important reaction intermediates in atmospheric chemistry. The observed bands have been assigned with an aid of a quantum chemical calculation at CCSD/aug-cc-pVDZ. These assignments have been confirmed by the experimental results using isotopic species of 18O2 or DBr. Their characteristic bands are discussed in comparison with those of HOOCl and HOClO from an HCl/O2 mixture [7]. Both HOOBr and HOBrO are found to be photolyzed with the UV light below 385 nm.
- Akai, Nobuyuki,Wakamatsu, Daisuke,Yoshinobu, Takeo,Kawai, Akio,Shibuya, Kazuhiko
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p. 117 - 120
(2011/01/05)
-
- One- versus two-electron oxidation with peroxomonosulfate ion: reactions with iron(II), vanadium(II), halide ions, and photoreaction with cerium(III)
-
The kinetics of the redox reactions of the peroxomonosulfate ion (HSO 5-) with iron(ll), vanadium(IV), cerium(lll),chloride, bromide, and iodide ions were studied. Cerium(lll) is only oxidized upon illumination by UV light and cerium
- Lente, Gabor,Kalmar, Jozsef,Baranyai, Zsuzsa,Kun, Aliz,Kek, IIdikoe,Bajusz, David,Takacs, Marcell,Veres, Lilla,Fabian, Istvaen
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p. 1763 - 1773
(2009/06/17)
-
- Uptake of NH3 and NH3 + HOBr reaction on ice surfaces at 190 K
-
The uptake of NH3 and the heterogeneous reaction of NH 3 + HOBr → products on ice surfaces at 190 K have been investigated in a flow reactor coupled with a differentially pumped quadrupole mass spectrometer. The uptake coefficient γt for NH3 was determined to be (3.8 ±1.4) × 10-4 on ice films at 189.8 K, for a partial pressure of NH3 in the range of 7.0 × 10-7 to 3.8 × 10-6 torr. The amount of NH 3 uptake on the ice film was determined to be >2.9 × 10 15 molecules/cm2, based on the total ice surface area at 189.2 K. The heterogeneous reaction of NH3 + HOBr on ice surfaces has been studied at 190 K. The reaction probability γt was determined to be (5.3 ±2.2) × 10-4 and was found to vary insignificantly as HOBr surface coverage changes from 2.1 × 10 13 to 2.1 × 1014 molecules/cm2. A reaction pathway is proposed on the basis of experimental observations.
- Jin, Ronghua,Chu, Liang T.
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p. 7833 - 7840
(2008/10/09)
-
- The far infrared rotational spectrum of HOBr: Line positions and intensities
-
The far infrared absorption spectrum of HOBr has been measured at high resolution between 100 and 400 cm-1 using high-resolution Fourier transform spectroscopy. It was possible to identify not only 1403 pure rotation lines within the vibrational ground state involving levels with rather high Ka quantum numbers (up to Ka=9) but also 457 pure rotation lines within the first excited vibrational state 31 up to K a=7. The ground state lines, combined with 32 microwave transitions available in the literature, were used for a new determination of the rotational constants up to higher orders for both isotopomers HO79Br and HO81Br, by least squares fitting of the observed line positions using a Watson-type Hamiltonian for the calculation of rotational energy levels. In the same way the 31 rotational lines were fitted together with the few existing microwave transitions and the energy levels derived from the study of the ν3 band (J. Orphal, Q. Kou, F. Kwabia Tchana, O. Pirali, and J.-M. Flaud, J. Mol. Spectrosc. 221 (2003), 239-243) leading to an improved set of Hamiltonian constants. Finally relative line intensities were measured and used for the determination of rotational corrections to the b-component of the permanent dipole moment.
- Orphal,Flaud,Kou,Kwabia Tchana,Pirali
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p. 153 - 159
(2007/10/03)
-
- Method of treating addiction or dependence using a ligand for a monoamine receptor or transporter
-
One aspect of the present invention relates to a method of treating of drug addiction or drug dependence in a mammal, comprising the step of administering to a mammal in need thereof a therapuetically effective amount of a heterocyclic compound, e.g., a 3-substituted piperidine. In a preferred embodiment, the method of the present invention treats cocaine addiction or methamphetamine addiction.
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-
-
- Methods for the preparation of concentrated aqueous bromine solutions and high activity bromine-containing solids
-
The invention includes convenient methods of preparing: (1) highly concentrated liquid bromine-containing biocidal solutions, (2) highly concentrated mixed halogen liquid bromine and chlorine-containing biocidal solutions, and (3) high-activity bromine-containing biocidal solids, all having excellent physical and chemical stability. One method yields solutions that have concentrations of bromine in excess of 18% as Br2 (8% as Cl2) in which the mole ratio of hydroxide ion to hydrogen ion source is at least 1.9:1. Another method employs elemental bromine in conjunction with a solid organic or inorganic halogenating agent to yield halogen solutions at concentrations greater than 22.9% as Br2 (10.2% as Cl2). This method can be performed under conditions that exceed the solubility of the active ingredient such that it crystallizes and is recovered as a hydrated or anhydrous salt in good yield.
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Page/Page column 6
(2008/06/13)
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- Mechanistic investigations of the BZ reaction with oxalic acid substrate, I. The oscillatory parameter region and rate constants measured for the reactions of HOBr, HBrO2, and acidic BrO3- with oxalic acid
-
This paper is the first part of a study reinvestigating the mechanism of the Belousov-Zhabotinsky (BZ) reaction of oxalic acid, which is the simplest organic substrate for a BZ oscillator. New experiments are performed to find the oscillatory region in 1 M sulfuric acid at 20°C. The removal rate of the end product bromine by an inert gas stream is a critical parameter here: oscillations can be observed only in a window of that parameter. The rate constant for the physical removal of bromine is measured as a function of the gas flow rate and reactor volume; furthermore, the rate constants of three component reactions important in this system are also determined. These are oxygen atom transfer reactions to die oxalic acid substrate from Br(I) (hypobromous acid), from Br(III) (bromous acid), and from Br(V) (acidic bromate) compounds. In these second-order reactions, the partial order of each oxybromine species is 1. The measured rate constants are kI = 17 ± 2 M-1 s-1, kIII = 4.2 ± 0.5 M-1 s-1, and kv = (7.47 ± 0.1) × 10-4 M-1 s-1. In the case of the HOBr-oxalic acid reaction, however, an additional parallel reaction route was found that has importance at higher HOBr concentrations. In the mechanism of that new route, the active species is Br2O, and the reaction order is not 1 but 2 with respect to HOBr. The rate constant of this parallel reaction is k I(2) = (1.2 ± 0.2) × 105 M 2 s-1. The k values measured here are compared with those reported earlier. A comparison of experimental results with computer simulations shows that free radicals play a negligible role or no role in the mechanism of the oxygen atom transfer reactions studied here.
- Pelle, Krisztina,Wittmann, Maria,Lovrics, Klara,Noszticzius, Zoltan,Liveri, Maria L. Turco,Lombardo, Renato
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p. 5377 - 5385
(2007/10/03)
-
- 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)
-
- Calorimetric study of the component steps of oscillating chemical reactions
-
The complexity of oscillating chemical reactions makes difficult a direct calorimetric study of them. It is more advantageous to carry out studies of the component steps and then try to put the parts together. Here, a mass-flow heat conduction calorimeter was used to study component reactions of two of the principal chemical oscillators. The studied reactions were: the net reaction of the inorganic set of the Belousov-Zhabotinsky reaction (BrO3; -+4Ce3++5H+?4Ce 4++HOBr+2H2O), and the Dushman reaction (IO 3-+5I-+6H+?3I 2+3H2O), which is a component of the Bray-Liebhafsky oscillator. The experimental values of the enthalpies of these two reactions are reported in this work.
- Agreda,Barragan,Gomez
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p. 875 - 881
(2008/10/09)
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- Vacuum synthesis and determination of the ionization energies of different molecular orbitals for BrOBr and HOBr
-
HOBr, as a reservoir for bromine, is an important bromine species in the atmosphere, and BrOBr as a precursor of HOBr. However, far less is known about their properties in the gas phase, and no gas-phase photoelectron spectroscopy (PES) investigation is available to date. This paper discusses vacuum synthesis of pure BrOBr and HOBr, and determination of ionization energies of different molecular orbitals by the PES and both the GAUSSIAN 2 (G2) and the outer valence Green's functional (OVGF) calculations.
- Qiao, Zhimin,Sun, Shutao,Sun, Qiao,Zhao, Jincai,Wang, Dianxun
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p. 7111 - 7114
(2007/10/03)
-
- Ligands for monoamine receptors and transporters, and methods of use thereof
-
One aspect of the present invention relates to heterocyclic compounds. A second aspect of the present invention relates to the use of the heterocyclic compounds as ligands for various mammalian cellular receptors, including dopamine, serotonin, or norepinephrine transporters. The compounds of the present invention will find use in the treatment of numerous ailments, conditions and diseases which afflict mammals, including but not limited to addiction, anxiety, depression, sexual dysfunction, hypertension, migraine, Alzheimer's disease, obesity, emesis, psychosis, schizophrenia, Parkinson's disease, inflammatory pain, neuropathic pain, Lesche-Nyhane disease, Wilson's disease, and Tourette's syndrome. An additional aspect of the present invention relates to the synthesis of combinatorial libraries of the heterocyclic compounds, and the screening of those libraries for biological activity, e.g., in assays based on dopamine transporters.
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-
-
- MCH antagonists and their use in the treatment of obesity
-
The present invention discloses compounds which, are novel antagonists for melanin-concentrating hormone (MCH), as well as methods for preparing such compounds. In another embodiment, the invention discloses pharmaceutical compositions comprising such MCH antagonists as well as methods of using them to treat obesity, metabolic disorders, eating disorders such as hyperphagia, and diabetes.
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-
- Heterogeneous hydrolysis and reaction of BrONO2 and Br2O on pure ice and ice doped with HBr
-
The rate of uptake of bromine nitrate (BrONO2) and dibromine monoxide (Br2O) on different types of ice, such as condensed (C), bulk (B), and single-crystal ice (SC) have been investigated in a Teflon-coated Knudsen flow reactor in the temperature range 180-210 K using mass spectrometric detection. For the whole temperature range the Br2O uptake kinetics is first order in [Br2O] with a mean initial uptake coefficient of γ0 = 0.24 ± 0.10, which leads to the exclusive formation of HOBr. The BrONO2 hydrolysis has been measured on B-,C-, and SC-type ice and leads to HOBr and Br2O on all types of ice. At a fixed temperature the rate law is first order in [BrONO2] with γ ≈ 0.3 at 180 K. The observed negative temperature dependence for the heterogeneous hydrolysis of BrONO2 on pure ice leads to Ea of -2.0 ± 0.2, -2.1 ± 0.2, and -6.6 ± 0.3 kcal/mol on C-, B- and SC-type ice, respectively. Despite the high reactivity of BrONO2 on ice substrates, the kinetics of interaction of BrONO2 on ice nevertheless depends on the type of ice used. No saturation of the uptake coefficient has been observed during the BrONO2 hydrolysis on ice in contrast to the ClONO2/ice system. On ice samples doped with approximately 5 × 1016 molecules HBr per cm3 the kinetics of the interaction of BrONO2 with HBr leads to an uptake coefficient similar to that for BrONO2 hydrolysis. The interaction of BrONO2 with HBr occurs via the hydrolysis of BrONO2 to HNO3 and HOBr where the latter reacts with HBr in a fast secondary reaction to produce Br2 with Ea = -1.2 ± 0.2 kcal/mol.
- Aguzzi, Arnaud,Rossi, Michel J.
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p. 5891 - 5901
(2007/10/03)
-
- Pulsed-accelerated-flow studies of the temperature dependence of fast reactions
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A pulsed-accelerated-flow (PAF) spectrometer (model V) capable of non-ambient temperature studies of fast reaction kinetics is described. The PAF method uses accelerated flow mixing of reactants during short time periods to enable the resolution of mixing and reaction rate constants. A new mixing/observation cell and cell supports are designed to permit measurement of reaction kinetics from 40°C to below 0°C. The cell consists of two machined PEEK [(-OC6H4OC6H4COC 6H4-)n] pieces joined together to give an internal solution distribution system, which greatly reduces the number of connections needed compared to previous instruments to bring the reactants together. The reaction between W(CN)84- and IrC 62- in 0.50 M H2SO4 is studied at 0.0, 25.0, and 40.0°C. Second-order rate constants of 0.650 × 10 8 M-1 s-1, 1.05 × 108 M -1 s-1, and 1.29 × 108 M-1 s-1 are obtained, respectively. These data give activation parameters of ΔH? = 10.0 ±0.8 kJ mol-1 and ΔS? = -58 ± 3 J mol-1 K-1. Activation parameters for reverse bromine hydrolysis (HOBr + Br- + H- → Br 2 + H2O) were determined from rate constants measured from 0.0 to 40.0°C. These were used to calculate the activation parameters for the forward bromine hydrolysis (ΔH? = 66 ±1 kJ mol -1 and ΔS? = 10 ± 20 J mol-1 K -1). The temperature dependence of the extremely rapid BrCl hydrolysis reaction (in equilibrium with BrCl2-) is determined as well. For reactions at temperatures of 25.0°C, 10.0°C, and 0.0°C the values are 3.3 × 106 s-1, 2.06 × 106 s-1, and 1.75 × 106 s -1, respectively. These values correspond to activation parameters of ΔH? = 15 ± 7 kJ mol-1 and ΔS ± = -71 ± 24 J mol-1 K-1 for BrCl hydrolysis. The Royal Society of Chemistry 2002.
- Becker, Robert H.,Bartlett, Wenzel P.,Urbansky, Edward T.,Margerum, Dale W.
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p. 695 - 700
(2007/10/03)
-
- Kinetic and products of the BrO+CH3SH reaction: Temperature and pressure dependence
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The kinetics and the mechanism of the reaction BrO + CH3SH → P (1) have been studied using the mass spectrometric discharge-flow method over the temperature range 259-333 K and at low total pressure between 0.5 and 3 Torr. The temperature depen
- Aranda, Alfonso,Díaz De Mera, Yolanda,Rodríguez, Diana,Salgado, Sagrario,Martínez, Ernesto
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p. 471 - 476
(2008/10/08)
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- Temperature-dependent rate coefficients for the reactions of Br(2P3/2), Cl(2P3/2), and O(3PJ) with BrONO2
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A laser flash photolysis-resonance fluorescence technique has been employed to investigate the kinetics of reactions of the important stratospheric species bromine nitrate (BrONO2) with ground-state atomic bromine (k1), chlorine (k2), and oxygen (k3) as a function of temperature (224-352 K) and pressure (16-250 Torr of N2). The rate coefficients for all three reactions are found to be independent of pressure and to increase with decreasing temperature. The following Arrhenius expressions adequately describe the observed temperature dependencies (units are 10-11 cm3molecule-1s-1): k1 = 1.78 exp(365/T), k2 = 6.28 exp(215/T), and k3 = 1.91 exp(215/T). The accuracy of reported rate coefficients is estimated to be 15-25% depending on the magnitude of the rate coefficient and on the temperature. Reaction with atomic oxygen is an important stratospheric loss process for bromine nitrate at altitudes above approximately 25 km; this reaction should be included in models of stratospheric chemistry if bromine partitioning is to be correctly simulated in the 25-35 km altitude regime.
- Soller,Nicovich,Wine
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p. 1416 - 1422
(2007/10/03)
-
- Kinetic study of the reactions of BrO radicals with HO2 and DO2
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The kinetics of the reactions of BrO radicals with HO2 and DO2 radicals, HO2 + BrO → products (1) and DO2 + BrO → products (3), have been studied by the mass spectrometric discharge flow method at temperatures between 230 and 360 K and at a total pressure of 1 Torr of helium. The rate constant of reaction 1 as determined by monitoring either the HO2 or the BrO decay (in excess of BrO or HO2, respectively) is given by the Arrhenius expression k1 = (9.4 ± 2.3) × 10-12 exp[(345 ± 60)77] cm3 molecule-1 s'1, with k1 = (3.1 ± 0.8) × 10-11 cm3 molecule-1 s-1 at T = 298 K, where the uncertainties represent 95% confidence limits and include estimated systematic errors. The rate constant of reaction 3, measured under pseudo-first-order conditions in an excess of BrO, is k3 = (3.9 ± 1.2) × 10-12 exp[(410 ± 80)/T] cm3 molecule-1 s-1, with k3 = (1.6 ± 0.4) × 10-11 cm3 molecule-1 s-1 at T = 298 K, where the uncertainties represent 95% confidence limits and include estimated systematic errors. The value of k3 was measured for the first time, whereas the value of k1 was compared with those from previous studies. From the observation that no ozone formed among the products of the HO2 + BrO reaction, an upper limit was derived for the channel HO2 + BrO → HBr + O3 (1b) of reaction 1: k1b/k1 0.004 at T = 298 K. The implication of this result for stratospheric bromine partitioning is briefly discussed.
- Bedjanian, Yuri,Riffault, Véronique,Poulet, Gilles
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p. 3167 - 3175
(2007/10/03)
-
- Kinetics and mechanisms of aqueous ozone reactions with bromide, sulfite, hydrogen sulfite, iodide, and nitrite ions
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Reactions of ozone with Br-, SO32-, HSO3-, I-, and NO2-, studied by stopped-flow and pulsed-accelerated-flow techniques, are first order in the concentration of O3(aq) and first order in the concentration of each anion. The rate constants increase by a factor of 5 × 106 as the nucleophilicities of the anions increase from Br- to SO32-. Ozone adducts with the nucleophiles are proposed as steady-state intermediates prior to oxygen atom transfer with release of O2. Ab initio calculations show possible structures for the intermediates. The reaction between Br- and O3 is accelerated by H+ but exhibits a kinetic saturation effect as the acidity increases. The kinetics indicate formation of BrOOO- as a steady-state intermediate with an acid-assisted step to give BrOH and O2. Temperature dependencies of the reactions of Br- and HSO3- with O3 in acidic solutions are determined from 1 to 25 °C. These kinetics are important in studies of annual ozone depletion in the Arctic troposphere at polar sunrise.
- Liu,Schurter,Muller,Aloisio,Francisco,Margerum
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p. 4436 - 4442
(2008/10/08)
-
- Kinetics of peroxynitric acid reactions with halides at low pH
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The oxidation of iodide, bromide, and chloride by peroxynitric acid (HOONO2) was studied by spectroiodometry. The second-order rate constants were found to be 890 (I-, 295 K), 0.54 (Br-, 295 K), and 0.0014 M-1 s-1 (Cl-, 298.2 K). No pH dependence was observed in any of the systems (pH 1.2-4.9). The temperature and ionic-strength dependencies of the chloride oxidation rate constant are 4.8×107 M-1 s-1 exp(-60 kJ mol-1/(RT)) and 6.0×10-4 M-1 s-1+1.7×10-4 M-2 s-1 μ, respectively, where μ is the ionic strength. HOONO2 also reduces halogens (X2), the active species being HO2, a radical in constant equilibrium with HOONO2. Under most conditions, the reduction can be explained quantitatively with a free-radical mechanism using known rate constants. Reduction by H2O2 was not significant. These systems also seem to be affected by reactions in addition to the direct oxidation and free-radical reduction. First, some iodine atoms are stored in a reservoir when initial concentrations of iodide and peroxynitric acid are near stoichiometric values, but we could not identify this reservoir. Second, reaction of HOONO2 with large excesses of KBr (in the 10-2 M range) gave inordinately fast and variable bromide oxidation. The addition of Cu2+ suppressed this at pH 1.7, suggesting an additional oxidation mechanism that involves HO2. On the basis of the above results, the potential role of HOONO2 in sea-salt chemistry has been evaluated. Given typical marine boundary layer conditions, it should be negligible in warm, clean, remote oceanic areas. In polluted coastal regions and/or at low temperatures, it might become marginally significant compared to other known reactions leading to halogen release from sea-salt particles.
- Regimbal, Jean-Michel,Mozurkewich, Michael
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p. 6580 - 6589
(2007/10/03)
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- Oscillations in the Bromomalonic Acid/Bromate System Catalyzed by [Ru(phen)3]2+
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We investigated the oscillatory behavior of a BZ system with bromomalonic acid and bromate as substrates and with [Ru(phen)3] SO4 as a catalyst. The observed oscillations can be well modeled with a theory based on two different feedback loops originally developed for a corresponding BZ system with [Ru(bipy)3] SO4 as a catalyst. Furthermore, we have reexamined the decomposition of acidic bromate. We conclude that the products of this reaction are HOBr and O2 rather than HOBr and perbromate; the rate constant for the decomposition reaction turns out to be 1000 times smaller for 1 M sulfuric acid solution than expected from earlier experiments performed with 3 M sulfuric acid solutions.
- Szalai, Istvan,Oslonovitch, Julia,Foersterling, Horst-Dieter
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p. 1495 - 1498
(2007/10/03)
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- Fourier transform infrared spectroscopic study of Br2O and OBrO
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Vibrational frequencies of gaseous Br2O and OBrO were observed using the Fourier transform infrared spectrometer. For the first time, bands at 629.0 cm-1 (ν3) and 532.9 cm-1 (ν1) were recorded for both Br-O asymmetric and symmetric stretching vibrations of gaseous Br2O. Two fundamental vibrations were observed at 798.7cm-1(ν1) and 846.3cm-1(ν3) for the O18BrO radical. In addition, two new peaks at 2333 cm-1 and 668 cm-1 were observed in a HOBr spectrum. They are tentatively assigned to the H-Br and Br-O stretching vibrations of a HOBr isomer on the basis of ab initio computational results.
- Chu, Liang T.,Li, Zhuangjie
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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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p. 117 - 123
(2008/10/08)
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- Heterogeneous interaction and reaction of HOBr on ice films
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The uptake coefficient γ of HOBr on the ice surface from 190 to 239 K has been investigated in a flow reactor interfaced with a differentially pumped quadrupole mass spectrometer, γ of HOBr on ice is in the range 0.11-7 × 10-3 at 190-218 K and is in the range 2 × 10-3 to 6 × 10-4 at 223-239 K. The desorption temperature Td of HOBr on the ice film was determined. Td increases with the HOBr exposure. The Monte Carlo simulation was used to shed light on the nature of the desorption and gas-surface interactions. This study extends our investigations to the reaction probability of the HOBr + HCl reaction. The reaction probability ranges from 0.05 to 0.23 at 190 K and 0.004 to 0.19 at 222 K as a function of PHCl, which varies from 1.3 × 10-7 to 8.8 × 10-6 Torr and 4.2 × 10-7 to 1.5 × 10-5 Torr, respectively. Kinetic analysis indicates that the heterogeneous reaction of HOBr + HCl follows the Langmuir-Hinshelwood type.
- Chu, Liang,Chu, Liang T.
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p. 8640 - 8649
(2007/10/03)
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- HOBr in Sulfuric Acid Solutions: Solubility and Reaction with HCl as a Function of Temperature and Concentration
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A detailed study of the interaction of HOBr and HCl in cold sulfuric acid solutions has been performed using a coated-wall flow tube coupled to an electron-impact mass spectrometer. The liquid-phase bimolecular rate constants, measured over a temperature range from 213 to 238 K and in solutions from 59.7 to 70.1 wt % composition, show a strong positive dependence on both acid composition and temperature. The solubility of HOBr has also been measured in these solutions by analyzing its time-dependent uptake. Henry's Law constants (H) determined from the measured values of HD1/2 and the liquid-phase diffusion coefficient (D) are independent of acid composition over the above range of solution compositions. The values of H demonstrate a clear Clausius-Clapeyron temperature dependence, with a heat of solution of -9 ± 1 kcal/mol. When the atmospheric importance of these data is assessed, two conclusions are reached. In the stratosphere, under aerosol conditions observed soon after the Mt. Pinatubo volcanic eruption, the rates of HCl activation via the HOBr/HCl heterogeneous reaction are comparable with the rate of activation via gas-phase reaction with OH at relatively warm temperatures (205-220 K), where other HCl-activating heterogeneous reactions occur slowly. In the high Arctic boundary layer, it is possible that significant HCl activation could occur when elevated levels of photochemically active bromine are present.
- Waschewsky, Gabriela C. G.,Abbatt, Jonathan P. D.
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p. 5312 - 5320
(2007/10/03)
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- On the mechanism of the BrO+HBr reaction
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The reaction of the bromine oxide radical, BrO, with HBr has been examined with coupled-cluster methods. The HO+HCl reaction is also examined and is used to calibrate the results for the BrO+HBr reaction. The heat of reaction and activation energy barrier
- Hansen, Jaron C.,Li, Yumin,Li, Zhuangjie,Francisco, Joseph S.
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p. 341 - 346
(2008/10/08)
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- Heterogeneous kinetics of the uptake of HOBr on solid alkali metal halides at ambient temperature
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The heterogeneous reactions of HOBr with solid crystalline NaCl [HOBr(g) + NaCl(s) → BrCl(g) + NaOH-(s)] and KBr [HOBr(g) + KBr(s) → Br2(g) + KOH(s)] substrates at ambient temperature have been investigated using a Teflon coated Knudsen cell reactor. Powder, grain, and spray-deposited salt substrates were used for the measurement of the HOBr reactivity. The observed uptake probability depends on the total external surface area of the salt substrates. For NaCl substrates, Br2 and BrCl are observed as products; for KBr substrates, Br2 is observed as the sole product. In both cases, a dependence of the initial uptake probability γ0 on HOBr flow rate has been observed. The initial uptake is large at low flow rate and 10 times smaller at high flow rate. Values of γ0 ≤ (6.5 ± 2.5) × 10-3 for NaCl and γ0 ≤ 0.18 ± 0.04 for KBr are obtained under our experimental conditions of limiting low flow rates akin to atmospheric conditions. The production of Br2 is observed even for HOBr interacting on solid NaNO3, a non-halogen containing substrate. The yield measurements imply that a HOBr self-reaction occurs on salt surfaces according to 2HOBr → Br2 + H2O + 1/2O2. The decrease in Br2 yield with increasing HOBr flow rate from 100 to 50% indicates that a competition between the heterogeneous reaction of HOBr with NaCl or KBr and the self-reaction of HOBr takes place on the solid salt surface under laboratory experimental conditions. The decrease of γ0 with time indicates that approximately 5-10% of the Br atoms on a KBr surface interact with HOBr.
- Mochida,Akimoto,Van Den Bergh,Rossi
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p. 4819 - 4828
(2007/10/03)
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- Fluorinated 2-nitroimidazole analogs for detecting hypoxic tumor cells
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Agents useful for detecting hypoxic tumor cells are provided. The compounds have the structural formula (I) STR1 Methods of using the compounds to detect hypoxic tumor cells are also provided, as are pharmaceutical compositions formulated with the novel compounds.
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- Photo-induced excitability in the tris-(bipyridyl) ruthenium(II)-catalyzed minimal bromate oscillator
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The tris-(bipyridyl)rutnenium(II)-catalyzed minimal bromate oscillator in its reduced state was found to exhibit an excitable pulse response to the pulsed light perturbation in the visible region, while the oxidized steady state did not respond to the light pulse. The oxidized steady state under the continuous illumination was also found to be insensitive to a negative light pulse perturbation. These results are successfully accounted for by the reaction scheme in which the photo-excited metal complex produces additional HBrO2 to enhance the autocatalytic process. No evidence was found to support the photo-production of Br- in the minimal bromate oscillator.
- Kaminaga, Akiko,Hanazaki, Ichiro
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- Cryptophycin derivatives and their use as anti-microtubule agents
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The invention provides novel cryptophycin compounds which can be useful for disrupting the microtubulin system, as antineoplastic agents, and for the treatment of cancer. The invention further provides a formulation for administering the novel cryptophycin compounds. The compounds are of the formula wherein Ar is phenyl or any simple unsubstituted or substituted aromatic or heteroaromatic group; R1is halogen, SH, amino, monoalkylamino, dialkylamino, trialkylammonium, alkylthio, dialkylsulfonium, sulfate, or phosphate; R2is OH or SH; or R1and R2may be taken together to form an epoxide ring, and aziridine ring, an episulfide ring, a sulfate ring, or monoalkylphosphate ring; or R1and R2may be taken together to form a second bond between C18and C19; R3is a lower alkyl group; R4is H; R5is H; R4and R5may be taken together to form a second bond between C13and C14; R6is benzyl, hydroxybenzyl, alkoxybenzyl, halohydroxybenzyl, dihalohydroxybenzyl, haloalkoxybenzyl, or dihaloalkoxybenzyl group; R7is H or a lower alkyl group; R8is H or a lower alkyl group; or R7and R8may optionally be taken together to form a cyclopropyl ring; R9is selected from the group consisting of H, a lower alkyl group, (C1-C3) alkylaryl, and aryl; R10is selected from the group consisting of H, a lower alkyl group, (C1-C3) alkylaryl, and aryl; R11is H; simple alkyl; phenyl, substituted phenyl, benzyl, substituted benzyl; X is O, NH or alkylamino; Y is C, O, NH, S, SO, SO2or alkylamino; and a pharmaceutically acceptable salt or solvate thereof.
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- Rate Coefficients for the Thermal Decomposition of BrONO2 and the Heat of Formation of BrONO2
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Rate coefficients (k-7) for the thermal decomposition of bromine nitrate, BrONO2 + M -> BrO + NO2 + M, have been obtained at temperatures between 320 and 340 K and pressures between 100 and 1000 Torr.These data are combined with recommended values for the reverse reaction to obtain an equilibrium constant for the reaction pair, KP,7 = 5.44E-9 exp(14192/T) atm-1, and a heat of reaction for the thermal dissociation of 28.2 +/- 1.5 kcal/mol at 298 K.This reaction enthalpy is used in conjunction with literature data to arrive at a consistent set of ΔH0f(298 K) data for BrONO2 (10.1 +/- 2.0 kcal/mol), BrO (30.4 +/- 2.0 kcal/mol), HOBr (-14.1 +/- 2.0 kcal/mol), and Br2O (27.3 +/- 2.0 kcal/mol).Additional measurements were made to determine the rate coefficient for Br atom reaction with BrONO2 (k11) relative to the rate coefficient for its reaction with CH3CHO (k12) at 298 K: k11/k12 = 12.5 +/- 0.6.This relative rate measurement yields a rate coefficient of (4.9 +/- 1.5)E-11 cm3 molecule-1 s-1 for k11, using the currently recommended value for k12.Approximate rate constant for reaction of NO (reaction 17) and BrNO (reaction 19) with BrONO2 were also obtained: k17 = 3E-19 cm3 molecule-1 s-1, k19 > 1E-16 cm3 molecule-1 s-1.
- Orlando, John J.,Tyndall, Geoffrey S.
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p. 19398 - 19405
(2007/10/03)
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- Dibromine monoxide, Br2O, and bromine dioxide, OBrO: Spectroscopic properties, molecular structures, and harmonic force fields
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Two bromine oxides with more than two atoms have been structurally characterized for the first time in the gas phase. Both molecules occur over a solid product formed in the reaction of O and Br2. Under certain conditions BrO, OBrO, and Br2O were obtained simultaneously.
- Muller,Miller,Cohen
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p. 2129 - 2131
(2008/10/09)
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- A gaskinetic investigation of HOBr reactions with Cl(2P), O(3P) and OH(2Π). the reaction of BrCl with OH(2Π)
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The reactions of HOBr with atomic chlorine (1), with oxygen (2) and with hydroxyl radicals (3) have been investigated at 300 K using the discharge flow technique with mass-spectrometric detection. The rate constants based on HOBr consumption have been determined to be k, = (8.0±0.4) · 10-11 and k2 = (3.1±0.2)· 10-11. For the reaction with OH radicals k3-13 was obtained. All rate constants are given in units cm3 molecule-1 s-1. The reactions of HOBr with Cl and with O are shown to proceed via bromine abstraction with formation of BrCl and BrO, respectively. The predominant channel in the reaction of OH with BrCl was identified to be step (4a) OH + BrCl → HOBr + Cl (4a) Based on the present kinetic investigation the heat of formation for HOBr at T = 300 K was evaluated to be ΔHf0 (HOBr) = -(60.22 ± 2) kJ · mol-1. VCH Verlagsgesellschaft mbH, 1996.
- Kukui,Kirchner,Benter, Th,Schindler
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p. 455 - 461
(2007/10/03)
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- Near-Threshold Photodissociation Dynamics of HOBr: Determination of Product State Distribution, Vector Correlation, and Heat of Formation
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The photodissociation dynamics of HOBr to give OH + Br fragments is investigated at 490 and 510 nm, close to the threshold for dissociation.The available energy resulting from dissociation at these wavelengths corresponds respectively to ca. 3500 and ca. 2700 cm-1.The nascent OH photofragments are characterized via polarization and Doppler spectroscopy using laser-induced fluorescence.At both wavelengths the OH fragments are found to be in their vibrational ground state with approximately ca. 150 cm-1 of rotational excitation.Almost the entire allotment of available energy is deposited into relative translation of the products (ca. 95percent).An analysis of the OH Doppler line shapes reveals that the correlation parameter is strongly positive (βμv = 0.72), indicating a definite preference for parallel alignment of the electronic transition moment and the recoil velocity vector of HOBr.This trend is independent of the photolysis wavelengths examined within the visible absorption band.All other vector correlations (,, and , although discernible, are not very pronounced.Comparison of the measured correlation with predictions of recent ab-initio calculations leads us to propose that the visible absorption band of HOBr arises from excitation to a low-lying triplet state of A symmetry which borrows intensity from singlet electronic state(s) of A' character.Furthermore, the present measurements allow us to determine the heat of formation of HOBr to be ΔHf0(0 K) = -49.5 +/- 4 kJ/mol (ΔHf0(300 K) = -60.0 +/- 4 kJ/mol).
- Lock, Michael,Barnes, Rhett J.,Sinha, Amitabha
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p. 7972 - 7980
(2007/10/03)
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- Temperature dependence of the rate constant for the HO2 + BrO reaction
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The rate constant for the HO2 + BrO reaction has been measured using the turbulent flow technique with high-pressure chemical ionization mass spectrometry for the detection of reactants and products. At room temperature and 100 Torr pressure, the rate constant (and the two standard deviation error limit) was determined to be (1.4 ± 0.3) × 10-11 cm3 molecule-1 s-1. The temperature dependence of the rate constant was investigated between 298 and 210 K, and the data was fit to the following Arrhenius expression: (2.5 ± 0.8) × 10-12 exp[(520 ±80)/T] cm3 molecule-1 s-1. Although the negative activation energy value agrees well with the current recommendation for stratospheric modeling, our absolute values for the rate constant are about a factor of 2 lower than this same recommendation.
- Elrod, Matthew J.,Meads, Roger F.,Lipson, Jennifer B.,Seeley, John V.,Molina, Mario J.
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p. 5808 - 5812
(2007/10/03)
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- Equilibrium and Kinetics of Bromine Hydrolysis
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Equilibrium constants for bromine hydrolysis, K1 = [HOBr][H+][Br-]/[Br2(aq)], are determined as a function of ionic strength (μ) at 25.0 °C and as a function of temperature at μ ? 0 M. At μ ? 0 M and 25.0 °C, K1 = (3.5 ± 0.1) × 10-9 M2 and ΔH° = 62 ± 1 kJ mol-1. At μ = 0.50 M and 25.0 °C, K1 = (6.1 ± 0.1) × 10-9 M2 and the rate constant (k-1 for the reverse reaction of HOBr + H+ + Br- equals (1.6 ± 0.2) × 1010 M-2 s-1. This reaction is general-acid-assisted with a Bronsted a value of 0.2. The corresponding Br2(aq) hydrolysis rate constant, k1, equals 97 s-1, and the reaction is general-base-assisted (β = 0.8).
- Beckwith, Richard C.,Wang, Tian Xiang,Margerum, Dale W.
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p. 995 - 1000
(2008/10/09)
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- Observation of a New Absorption Band of HOBr and Its Atmospheric Implications
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A new absorption band of HOBr centered near 440 nm is detected by monitoring the yield of OH radicals as the wavelength of an excitation laser is scanned over the region from 440 to 650 nm.The band is believed to arise from excitation to a triplet state of HOBr, and although its peak absorption cross section is fairly modest, ?max ca. 9E-21 cm2, its influence on determining the photochemical lifetime of HOBr is large due to its proximity to the peak of the solar actinic flux.Preliminary estimates suggest that inclusion of absorption by this new band system will shorten the photochemical lifetime of tropospheric HOBr in the polar regions by a factor of 2 compared to the recently recommended value based on the near-UV absorption bands alone.
- Barnes, Rhett J.,Lock, Michael,Coleman, Jack,Sinha, Amitabha
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p. 453 - 457
(2007/10/03)
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- Bromine Superoxide: Generation and Photoisomerization into Bromine Dioxide
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Flash pyrolysis of a gas mixture containing bormine, oxygen and argon yields bromine superoxide, which can be identified IR- and UV-spectroscopically after trapping the pyrolysate at 12 K. Matrix irradiation transfers bromine superoxide into bromine dioxide. The backreaction can be induced by changing the wavelength. Even at room temperature a detectable amount of bromine superoxide is formed upon preparing a mixture of gaseous bromine, oxygen and argon.
- Maier, G.,Bothur, A.
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- Non-metal redox kinetics: Oxidation of bromide ion by nitrogen trichloride
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Bromide ion reacts with NCl3 to generate NBrCl2 with the rate expression d[NCl3]/dt = 12[Br-][NCl3] (M s-1 at 25.0°C, μ = 0.50 M). The NBrCl2 intermediate subsequently reacts with Br- to give N2, Br2, and Cl- with the rate expression -d[NBrCl2]/dt = (0.05 + 5.3[Br-])[NBrCl2]. The overall stoichiometry from pH 3.2 to 6.5 corresponds to 2NCl3 + 6Br- → N2 + 3Br2 + 6Cl-. Rate constants for NCl3 reactions show extreme sensitivity to nucleophilic strength with SO32- > CN- > I- ? Br-. Aqueous absorption spectra are determined for NCl3 with maxima at 336 nm (∈ 190 M-1 cm-1) and 220 nm (∈ 5320 M-1 cm-1) and for NBrCl2 with a maximum at 228 nm (∈ 4800 M-1 cm-1). Spectral bands for NCl3, NBrCl2, NBr2Cl, and NBr3 shift systematically with the number of bromine atoms from 220 to 256 nm. The rate constants for the reactions of NHCl2 with Br2, HOBr, and Br- are much larger than that for the reaction of NCl3 with Br-.
- Gazda, Michael,Kumar, Krishan,Margerum, Dale W.
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p. 3536 - 3542
(2008/10/08)
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- Gas-Phase UV/Visible Spectra of HOBr and Br2O
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The gas-phase UV/visible absorption spectrum of HOBr, an important atmospheric trace species, is reported for the first time.The HOBr spectrum, measured over the range 200-420 nm, consists of two absorption bands peaking near 280 nm (?max = (3.
- Orlando, John J.,Burkholder, James B.
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p. 1143 - 1150
(2007/10/02)
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- Kinetics and Mechanism of the BrO+HO2 Reaction
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Using the discharge flow-mass spectrometric technique, the kinetics and mechanism of the BrO+HO2 reaction have been investigated in the temperature range 233-344 K.With an excess of HO2 over BrO, the rate constant was found to be k1=(4.77+/-0.3
- Larichev, Michael,Maguin, Francoise,Bras, Georges Le,Poulet, Gilles
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p. 15911 - 15918
(2007/10/02)
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