Tribromide Ion Research Articles

Singlet oxygen production by lactoperoxidase: Halide dependence and quantitation of yield

Chemiluminescence at 1268 nm was used to measure singlet oxygen production in the lactoperoxidase(hydrogen peroxide)halide systems. The use of a liquid-nitrogen-cooled germanium detector permitted the measurement of singlet oxygen production rates as low as 30 nmol min −1. Under optimal conditions using bromide ion as a substrate, lactoperoxidase produced singlet oxygen in stoichiometric amounts consistent with the mechanism. ▪ ▪ The oxidized bromine species, tribromide ion, bromine and hypobromous acid, were not significant final reaction products. No 1268 nm chemiluminescence was detected with chloride ion or iodine ion. Lactoperoxidase does not oxidize chloride ion. The absence of 1268 nm chemiluminescence does not rule out some singlet oxygen production in the lactoperoxidase(hydrogen peroxide)iodide system, since iodine is known to quench single oxygen.

ChemInform Abstract: SURFACE‐ENHANCED RAMAN SPECTROSCOPY OF PLATINUM. 3. ENHANCED LIGHT SCATTERING G OF ELECTROGENERATED BROMINE AND TRIBROMIDE IONS COADSORBED ON A PLATINUM ELECTRODE

Chemischer InformationsdienstVolume 15, Issue 22 Physical Inorganic Chemistry ChemInform Abstract: SURFACE-ENHANCED RAMAN SPECTROSCOPY OF PLATINUM. 3. ENHANCED LIGHT SCATTERING G OF ELECTROGENERATED BROMINE AND TRIBROMIDE IONS COADSORBED ON A PLATINUM ELECTRODE B. H. LOO, B. H. LOOSearch for more papers by this authorY. G. LEE, Y. G. LEESearch for more papers by this author B. H. LOO, B. H. LOOSearch for more papers by this authorY. G. LEE, Y. G. LEESearch for more papers by this author First published: May 29, 1984 https://doi.org/10.1002/chin.198422009Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume15, Issue22May 29, 1984 RelatedInformation

Singlet oxygen production by chloroperoxidase-hydrogen peroxide-halide systems.

Singlet oxygen production in the chloroperoxidase-hydrogen peroxide-halide system was studied using 1268 nm chemiluminescence. With chloride or bromide ions, singlet oxygen is produced by the mechanism (formula; see text) (formula; see text) where X- is chloride or bromide ion. Under conditions where there is high enzyme activity and when Reaction B is fast relative to Reaction A, singlet oxygen is produced in near stoichiometric amounts. In contrast, when Reaction A is fast relative to Reaction B, oxidized halogen species (chlorine and hypochlorous acid for chloride ion; bromide, tribromide ion, and hypobromous acid for bromide ion) are the principle reaction products. With iodide ion, no 1268 nm chemiluminescence was detected. Past studies have shown that iodine and iodate ion are the major end products of this system.

Surface-enhanced Raman spectroscopy of platinum. 3. Enhanced light scattering of electrogenerated bromine and tribromide ions coadsorbed on a platinum electrode

Observation d'une diffusion Raman augmentee en surface a partir d'ions bromure et tribromure, electrogeneres anodiquement et coadsorbes sur une electrode de platine

On bromination of 2,4-pentanedionato-copper(II)

Treatment of bis-2,4-pentanedionato-copper(II), with liquid bromine, at room temperature, gave a low melting dark green reaction product containing weakly coordinated tribromide ion. Characterization of this product using elemental analysis, conductivity, electronic, IR and ESR-spectra was carried out and suggested that the composition of the product was [Cu(HacacBr)Br(Br 3)].

Contribution a L'Étude du Comportement du Chlore et du Brome Dans Les Solvants Nucléophiles

AbstractIn this paper, we study the oxydant concentration stability of diluted halogen solutions of bromine, chlorine in organic solvents: acetonitrile, nitromethane, N,N‐dimethylformamide, N,N‐dimethylacetamide, 1 methylpyrrolidinone‐2, tetrahydrofuran, dimethylsulfoxide, tetramethylurea and tetramethylthiourea.Raman spectroscopy examinations of halogen Solutions show undoubted formation of trichloride and tribromide ions in N,N‐disubstituted amide solvents. This specific chlorine solvation explains the immonium chloride formation observed during styren chloration in N,N‐dimethylformamide. Bromine solvation in dimethylsulfoxide and other nucleophilic solvents are also studied.

Competing mechanistic pathways in the bromination of 1,3-butadiene with molecular bromine, pyridine-bromine complex, and tribromide ion

Competing mechanistic pathways in the bromination of 1,3-butadiene with molecular bromine, pyridine-bromine complex, and tribromide ion

Bromination of 9-Allyltriptycenes: Bromoolefin Formation and Lifetime of an Intervening Bromonium Ion

Abstract The bromination of 9-allyl-1,2,3,4-tetrachlorotriptycene affords a mixture of bromoolefins together with a minor quantity of the corresponding dibromide. By the examination of the reactions of model compounds, it is concluded that the first attack of bromine on the olefinic bond takes place in the meso rotamer and the resulted bromonium ion collapses either by attack of the tribromide ion to produce the dibromide or by internal rotation about the C9–Callyl bond followed by attack of the tribromide ion to produce the bromoolefin. Examination of the bromoolefin/dibromide ratios at various temperatures suggests that the activation energy for the attack of the tribromide ion on the bromonium ion is ca. 3 kcal/mol higher than the rotational barrier.

Bromine Diffusion Through Nafion® Perfluorinated Ion Exchange Membranes

The diffusion coefficient of bromine through Nafion® perfluorinated ion exchange membranes has been determined as a function of the equivalent weight of the membrane, the membrane pretreatment, and the solute concentration. The measured voltage decay of bromine concentration cells is interpreted in terms of a simple mathematical model that takes into account the solution equilibrium between bromine, bromide, and tribromide ions followed by diffusion of bromine or tribromide ions through the membrane. Diffusion coefficients fall in the range of corresponding to bromine fluxes from or current densities from 0.3 to 10 mA/cm2. Bromine fluxes as a function of solute concentration are determined directly by quantitative cathodic reduction of bromine or tribromide after diffusion through the membrane.

Permercurated arenes

Permercuration of sodium benzoate, nitrobenzene, benzamide, and benzene, and pentamercuration of benzene have been achieved by heating the appropriate arenes or monomercurated arenes with mercuric trifluoroacetate, while anisic acid gave permercurated anisole; the products react with tribromide ions to give the corresponding polybromobenzenes.

Transfer diffusion. V. Kinetics and mechansim of the exchange reaction between bromide and tribromide ions

Transfer diffusion. V. Kinetics and mechansim of the exchange reaction between bromide and tribromide ions

Kinetics of bromine addition to unsaturated sulphones

The effect of added electrolytes on the kinetics of bromine addition to several α, β- and β,γ-unsaturated sulphones in glacial acetic acid at 30° has been studied. The presence of bromides leads to a general decrease in the rate of bromine addition, the decrease being pioportional to the concentration of the added bromide. This may be due to the decrease in the concentration of molecular bromine, the reactive electrophilic species, as a result of its combination with the bromide ion to form the tri-bromide (Br3 −) ion. The retarding effect (at a particular concentration) of the different bromides on the rate of bromine addition follows the order HBr > KBr > LiBr, probably due to the difference in the degree of dissociation of these bromides in glacial acetic acid. In the presence of acetate ions, there is a general increase in the rate of bromine addition to all the sulphones, presumably due to a salt effect. In the case of the sulphones having a nitro group and exhibiting a low electrophilic rate of bromine addition, the ratios of the rate constants of the acetate catalysed to uncatalysed additions are much higher than the ratios observed for other sulphones. The strikingly higher rate ratios observed for the nitrosubstituted sulphones indicate that in these compounds there is a considerable feasibility of a nucleophilic mode of addition by Br2OAc− ion. The effect of added lithium chloride seems to be somewhat complex.

Properties of some disulphones: acidities, rates of ionization and bromination, and hydrogen isotope effects

Measurements are reported of the rates of bromination and acid dissociation constants of the disulphones (EtSO2)2-CHMe, (MeSO2)2CH2, (EtSO2)2CH2, (EtSO2)2CHPh, and (EtSO2)2CHBr. For (EtSO2)2CHMe the order with respect to bromine is between zero and unity, and it was possible to derive both rates of ionization (and of the reaction of the anions with acids) and velocity constants for the reaction between anion and bromine or tribromide ion. For the remaining disulphones only the latter were obtained.

Polarography of Halides in Dimethylformamide. V. Bromine and the Tribromide Ion

Abstract The polarographic behavior of bromine and the tribromide ion at the dropping mercury electrode was investigated in dimethylformamide. A freshly-prepared solution of bromine gives two cathodic waves. When the solution is allowed to stand at 25°C in the dark, however, the first wave gradually becomes anodic, independently of the electrolysis. When the first wave is completely anodic, an equilibrium is established. The resulting polarogram coincides with that of hydrogen tribromide. The formation of hydrogen tribromide was ascribed to the chemical reduction of bromine by dimethylformamide. Diffuse sunlight accelerates the decomposition of bromine, which in turn yields hydrogen bromide. It was also suggested that, when the dropping mercury is used as an indicator electrode, bromine and the tribromide ion may react with the dropping mercury prior to being electrolyzed, forming mercuric bromide and the tribromomercurate ion respectively, which may in turn depolarize the indicator electrode.

Stereochemistry of tellurium(II) complexes and related compounds

Abstract

Reaction of transition metals with bromine in acetonitrile

The reactions of titanium, vanadium, and chromium with bromine in acetonitrile have been re-examined. The major products of the reaction were TiBr4(MeCN)2, VBr2(Br3)(MeCN)3, and [CrBr2(Br3)(MeCN)2]n. The latter polymeric complex breaks down in two steps in the parent solvent to form CrBr2(Br3)(MeCN)3 followed by CrBr3(MeCN)3. The simple halide complex was found to be identical with the complex formed from CrBr3 and MeCN. Spectral and conductivity studies indicate that the tribromide ion is bonded directly to the metal in these cases. In solution the vanadium complex appears to undergo co-ordination disproportionation. The mechanism of the reaction and the bonding in the complexes are discussed.

Kinetics of the reactions of olefins with halogens in aqueous solution. Part III. Reaction of bromine with acrylic acid, crotonic acid, and ethyl acrylate

Kinetic measurements are reported for the reaction of aqueous bromine with acrylic and crotonic acids, for both of which the anion is much more reactive than the undissociated molecule. Velocity constants are derived for the reaction of acrylate and crotonate ions with molecular bromine, and of crotonic acid with molecular bromine and tribromide ion, but no contribution could be detected from the reaction of either anion with tribromide ion, or of undissociated acrylic acid with either brominating agent. The ratios of bromohydrin to dibromide in the products of the reaction of bromine with acrylic acid and ethyl acrylate have been measured over a range of bromide ion concentrations. The observed velocity constants and competition factors are discussed in relation to the reaction mechanism.

The interaction of starch with bromine in acid solution

Amylose is precipitated from aqueous solution by the tribromide ion and can thus be separated from amylopectin. The adsorption of bromine by dissolved amylose was demonstrated potentiometrically. The rate of oxidation of starch by bromine at pH 1.7, 3.0, and 5.9 is a fist-order reaction with respect to bromine, and increases rapidly with the pH.

Nuclear quadrupole resonance study of several tribromide ions

Nuclear quadrupole resonance study of several tribromide ions

Kinetics of the reactions of olefins with halogens in aqueous solution. Part II. Reactions of bromine with various olefins, and of hydrogen bromide with some epoxides

Kinetic results are reported for the reaction of nine olefins with bromine in aqueous solution. Velocity constants were obtained for reaction with molecular bromine and with tribromide ion, and, for two olefins, also with the ions Br2Cl– and BrCl2–. The relative amounts of bromohydrin and dibromide produced were determined as a function of bromide ion concentration for eight olefins. For most of the reactions studied here and in previous work there is no correlation between the product composition and the kinetics, and it is concluded that an intermediate formed in the rate-determining step then reacts rapidly with either water or bromide ion. The bromination of diethyl fumarate, however, appears to involve simultaneous electrophilic attack by a bromine molecule and nucleophilic attack by water or bromide ion. Both diethyl furmarate and diethyl maleate give the meso-form of diethyl dibromosuccinate. Kinetic measurements with three epoxides support a cyclic bromonium ion as the intermediate in the reactions between olefins and bromine, but other formulations are possible. The velocity constants for reaction with bromine or tribromide ion, varying over about eleven powers of ten, show an approximate correlation with Taft's σ* substituent constants.