13517-11-8Relevant articles and documents
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
Pelle, Krisztina,Wittmann, Maria,Lovrics, Klara,Noszticzius, Zoltan,Liveri, Maria L. Turco,Lombardo, Renato
, p. 5377 - 5385 (2004)
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.
On the Use of Ion-Selective Electrodes for Monitoring Oscillating Reactions. 2. Potential Response of Bromide- and Iodide-Selective Electrodes in Slow Corrosive Processes. Disproportionation of Bromous and Iodous Acids. A Lotka-Volterra Model for the Halate Driven Oscillators
Noszticzius, Z,Noszticzius, E.,Schelly, Z. A.
, p. 510 - 524 (1983)
The potential response of silver halide membrane electrodes to the corrosive bromous, bromic, iodous, and iodic acids is investigated in sulfuric acid solutions ( = 0.15 and 1.5 M), typical media for several well-known oscillating reactions.The syntheses of the materials (bromide-free NaBrO2 and HIO2) needed for the experiments are described.The potentials recorded as a function of time were used for the determination or estimation of several rate constants at 24 +/- 1 deg C: the disproportionation rate constant of HBrO2 is kB1 = (1.4 +/- 0.2) * 103 M-1 s-1 (in 0.15 M H2SO4) and (3.8 +/- 1.0) * 103 M-1 s-1 (in 1.5 M H2SO4): the corresponding value for HIO2 is KI1 -1 s-1 (in 0.05-0.15 M H2SO4); the disproportionation of HIO2 is autocatalytic, the rate-determining step is a reaction of HIO2 with H2OI+, the rate constant of which is kI5 = 130 +/- 5 M-1 s-1 ( in 0.15 M H2SO4); the rate constants of the reactions of HBrO2 with Br- and H+, and HIO2 with I- and H+ are 106 B2 6 M-2 s-1 (in 1.5 M H2SO4) and 106 I2 7 M-2 s-1 (in 0.15 M H2SO4), respectively.The corrosive reactions of the halous and halic acids with halide ions are much slower than those of hypohalous acids, which fact required the development of the theory for slow corrosive reactions.Criteria for the definitions of slow and fast corrosive reactions are given.The possibility of a second autocatalytic process in the halate driven oscillating reactions is demonstrated.On the basis of these results, a generalized Lotka-Volterra scheme is proposed for the BZ, BL, and BR oscillators.
Pulsed-accelerated-flow studies of the temperature dependence of fast reactions
Becker, Robert H.,Bartlett, Wenzel P.,Urbansky, Edward T.,Margerum, Dale W.
, p. 695 - 700 (2002)
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.
Growth of spherulitic crystal patterns in a Belousov-Zhabotinski type reaction system
Yadav, Narendra,Srivastava
, p. 1080 - 1087 (2011)
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.
Selective Monitoring and Imaging of Eosinophil Peroxidase Activity with a J-Aggregating Probe
Kim, Tae-Il,Hwang, Byunghee,Lee, Boeun,Bae, Jeehyeon,Kim, Youngmi
, p. 11771 - 11776 (2018)
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.
High-Quantum-Yield Mitochondria-Targeting Near-Infrared Fluorescent Probe for Imaging Native Hypobromous Acid in Living Cells and in Vivo
Liu, Xiaojun,Zheng, Aishan,Luan, Dongrui,Wang, Xiaoting,Kong, Fanpeng,Tong, Lili,Xu, Kehua,Tang, Bo
, p. 1787 - 1792 (2017)
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.
Heterogeneous hydrolysis and reaction of BrONO2 and Br2O on pure ice and ice doped with HBr
Aguzzi, Arnaud,Rossi, Michel J.
, p. 5891 - 5901 (2002)
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.
Kinetics of peroxynitric acid reactions with halides at low pH
Regimbal, Jean-Michel,Mozurkewich, Michael
, p. 6580 - 6589 (2000)
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.
The Disproportionation of HBrO2, Key Species of the Belousov-Zhabotinskii Oscillating Reaction
Ariese, Freek,Ungvarai-Nagy, Zsuzsanna
, p. 1 - 4 (1986)
The rate constant of the disproportionation of HBrO2, 2HBrO2->HBrO3 + HOBr, an important step of the Belousov-Zhabotinskii oscillating system, was measured spectrophotometrically at 240 nm by using stopped-flow techniques.Its value at =0.5 M, T=24
Kinetic and products of the BrO+CH3SH reaction: Temperature and pressure dependence
Aranda, Alfonso,Díaz De Mera, Yolanda,Rodríguez, Diana,Salgado, Sagrario,Martínez, Ernesto
, p. 471 - 476 (2002)
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
