Bromine In Aqueous Solution Research Articles

Specular CuInSe2 films for solar cells

Specular CuInSe2 films suitable for solar cell devices have been produced by etching the as-deposited films in an aqueous bromine solution. Structural analysis and device results indicate that the CuInSe2 films are compositionally and electronically homogeneous even though the films are deposited in two distinct layers. The implications for improvements in CuInSe2 cell and module performance are discussed.

Selective bromination of the aromatic ring in ω-phenylpolyoxaalkanes and alkanols in micelles

The regioselectivity of bromination of ω -phenylpolyoxaalkanes and alkanols by bromine in aqueous solution of dodecyl sulfate (SDS) and aqueous solution of cetyltrimethylammonium bromide (CTAB) are shown to be related to the average orientation of substrate as indicated by 1H NMR studies. Thus ortho-bromination is promoted at higher concentrations of the surfactant relative to pure water. In contrast, at an equal ratio of the surfactant and substrate para-bromination is promoted. The results are discussed with respect to the average orientation of substrate in a micellar microenvironment and the formation of an ether-bromine comples as possible bromination agent.

Kinetics of component reactions of the Belousov-Zhabotinskii type oscillation system with oxalic acid and hypophosphite ions

The authors studied the kinetics of oxidation of oxalic acid and hypophosphite ions with bromate ions, aqueous solution of bromine, and Mn(III) ions in the medium of aqueous sulphuric and perchloric acids. The kinetics of these two-component reactions of the Belousov-Zhabotinskii type oscillation system was considerably influenced by the addition of a third component.

Indirect spectrophotometric microdetermination of some carboxylic acids and unsaturated organic compounds in aqueous solution

Some carboxylic acids (including formic, oxalic and malonic acids) and unsaturated compounds (including crotonic acid, crotonyl chloride and crotonaldehyde) were determined spectrophotometrically by reaction with excess bromine in aqueous solution. The unconsumed bromine was reacted with excess of chloranil and the absorbance of the unconsumed chloranil was measured at 292 nm (pH 9). Microgram amounts of the compounds can be determined with an accuracy of better than ±3% and a relative standard deviation of <3%. The effect of foreign acids on the determination of the carboxylic acids was investigated.

The reactions of perfluoro- and α,α-dichloropolyfluoroalkanesulfinates

Sodium perfluoroalkanesulfinate, RFSO2Na [RFCl(CF2)4, 1a; CF3(CF2)5, 1b; Cl(CF3)6, 1c] reacted with bromine in aqueous solution to give the corresponding sulfonyl bromide RFSO2Br (2a-2c) and in acetonitrile or acetic acid, to form perfluoroalkyl bromide RFBr (3a-3c). Heating in acetonitrile at 80°C, 2a-2c were converted smoothly into 3a-3c. However, reaction of sodium α,α-dichloropolyfluoroalkanesulfinate RCCl2SO2Na (RCF3, Cl(CF2)n, n=2, 4, 6, 5a-5d) with bromine in aqueous solution gave directly the corresponding bromoalkanes 1-bromo-1,1-dichloropolyfluoroalkane RCCl2Br (6a-6d). In aqueous potassium iodide solution, 1a-1c, 5a and 5b also reacted with iodine to form the corresponding iodo-polyfluoroalkane 4a-4c, 7a and 7b directly. 6a and 7a underwent free radical addition to alkene readily in the presence of free radical initiator and reacted with Na2S2O4 in the usual way to form α,α-dichloropolyfluoroethane sulfinate (5a). 5a was stable in strong acid, but reacted with strong base to yield 10. 5a was oxidised by hydrogen peroxide to the sulfonate 11 and reduced by zinc in dilute acid to from the α-chloro sulfinate 12.

On the reaction of furan with bromine in aqueous solution. Observation of the slow hydration of malealdehyde

The rate of reaction of furan with bromine in aqueous solution has been measured and the rate constant obtained by Williamson and Coller is confirmed. However, it is now found that the reaction of bromine with furan in water has two distinct stages: attack of bromine leading to the formation of malealdehyde 3 and hydration of 3 to a 2:1 mixture of the geometrical isomers of its cyclic hydrate 4. This second, slower process is observable by stopped-flow uv spectrophotometry occurring after the consumption of bromine. The observed kinetics are very similar to those recently found for the analogous hydration of phthalaldehyde by McDonald and Martin.

1,3‐dihydroxybenzene‐2‐13C: Its preparation and reaction with chlorine and bromine in aqueous solution

Abstract1,3‐cyclohexanedione‐2‐13C was prepared by intramolecular Claisen condensation of methyl 5‐oxohexanote‐6‐13C with sodium methoxide. Formation of the ketoester starting material involved treatment of a mixed dicarboxylic anhydride with an isotopicallylabelled Grignard reagent, methyl‐13C magnesium iodide. Dehydrogenation of carbon‐13 labelled cyclohexanedione over a palladium/carbon catalyst produced 1,3‐dihydroxybenzene‐2‐13C. Chlorination and bromination of dihydroxybenzene in aqueous solution yielded isotopically‐labelled chloroform and bromoform, each having enriched carbon‐13 contents equivalent to that of the organic substrate.

Relative toxicities of phorate and some of its metabolites to Aphis fubae Scop

AbstractAn aqueous solution of bromine was used to oxidise 14C‐labelled phorate to its metabolites. A substantial amount of [14C]phorate sulphone (O,O‐diethyl S‐ethylsulphonyl[14C]methyl phosphorodithioate) with minute quantities of [14C]phorate sulphoxide (O,O‐diethyl S‐ethylsulphinyl[14C]methyl phosphorodithioate) and [14C]phoratoxon sulphoxide (O,O‐diethyl S‐ethylsulphinyl[14C]methyl phosphorothioate) were recovered using this method. Various concentrations of [14C]phorate and these toxic metabolites were individually incorporated in an artificial diet and fed to Aphis fabae Scop. Mortality was recorded after 48 h. The toxic fractions of the compounds were extracted from the diet and their radioactivity was measured to determine the dose unit. The aphids feeding on diet containing high concentrations of [14C]phorate sulphoxide and [14C]phoratoxon sulphoxide were seen wandering restlessly, which suggested that the acceptability of the diet had been changed by the presence of these metabolites. Phorate appeared to be the most toxic to the aphids, followed by phorate sulphone, phorate sulphoxide and phoratoxon sulphoxide in that order; the reasons for this are discussed.

Sonoluminescence from aqueous solutions of bromine and iodine

Sonoluminescence from aqueous solutions of bromine and iodine

Surface characteristics and surface behaviour of polymer carbons—V: Interaction of polymer carbons with bromine in aqueous solutions

Interaction of polymer charcoals with bromine in aqueous solutions results in the conversion of bromine into HBr and its fixation by the charcoals. The amount of bromine converted into HBr is related to the surface acidity of the char while the amount fixed depends upon the nature of the char and the history of its formation. PVDC and Saran charcoals adsorb appreciably larger amounts of bromine than PF and UF charcoals prepared at the same temperature. The adsorption decreases on outgassing the chars at 1000°C and the decrease is only slight in case of PVDC and Saran chars. The adsorption of bromine involves two different mechanisms. In case of the highly porous charcoals such as those of PVDC and Saran prepared by the carbonisation of oxygen free polymers, the adsorption of bromine occurs largely in pores. In the case of less porous charcoals such as those of PF and UF prepared by the carbonisation of oxygen containing polymers, the adsorption of bromine takes place partly by addition at the unsaturated sites and partly by substitution in place of bonded hydrogen.

Bromine oxidation of [formula omitted] and sucrose

Sucrose and 1,2-O- isopropylidene-α- d-glucofuranose ( 1) were oxidised with bromine in aqueous solution at pH 7 and room temperature. The resulting keto derivatives were converted into their more-stable O-methyloximes, which were characterised by spectroscopic and chromatographic methods. Oxidation of 1 occurred at C-3 and C-5, with a preference for C-5. In the sucrose derivatives isolated after oxidation, those having a keto group in the glucopyranosyl moiety preponderated. The axial fructofuranosyl aglycon protects position 3 in the glucopyranosyl group and oxidation occurs only at C-2 and C-4. Small amounts of sucrose oxidised at C-3 in the fructofuranosyl moiety were also found.

The detection of the thiocyanate ion (SCN−) in hen's egg by gas chromatography

AbstractThe free thiocyanate ion (SCN−) content of eggs from five different strains of hen was determined by gas chromatograph as cyanogen bromide after treating the deproteinised liquid whole egg with aqueous bromine solution. Interference by cyanide and residual protein after deproteinisation with phosphotungstic acid was not found to have any noticeable effect on the results. Samples spiked with known concentrations of SCN− gave recoveries of 95%. The levels of SCN− detected ranged from 0.54–0.675 mg kg−1. There was very little variation in the levels detected from one strain of hens over a period of 10 weeks. The amount present presumably originating from the detoxification of cyanide in the liver and kidney would be insufficient to promote bactericidal activity, when incorporated into the lactoperoxidase/thiocyanate/hydrogen peroxide antimicrobial system.

Kinetics of hydrolysis of bromine in aqueous solutions of chloride and bromide ions

1. Using the temperature-jump method, the authors have investigated chemical relaxation in aqueous bromide solutions containing chloride and bromide ions. 2. The reaction of BrCl with a water molecule is far more rapid than the analogous reaction between bromine and water molecules. 3. The rate constant of the reaction Br2OH- + H+ ⇌ Br2 + H2O is close to the diffusion limit of the rate constant of a bimolecular reaction in a solution. 4. The rate constant of the reaction BrClOH- +H+ ⇌ BrCl + H2O is much lower than the values of the diffusion limit, indicating the presence of a small free-energy barrier in this proton transfer process.

Bromine oxidation of methyl α- and β-pyranosides of D-galactose, D-glucose, and D-mannose

Methyl α- and β-pyranosides of D-galactose, D-glucose, and D-mannose have been oxidized with bromine in aqueous solution at various pH values. The resulting keto glycosides were converted into their more-stable O-methyloxime derivatives which were characterized by spectroscopy and chromatography. Oxidation at a ring carbon atom where the hydrogen is axial is hindered by bulky substituents in syn ( i.e., a 1,3) diaxial relationship. Thus, the aglycon group in the α anomers protects position 3, the axial HO-4 in galactopyranosides protects position 2, and the axial HO-2 in mannopyranosides protects position 4 from oxidation.

Kinetics and mechanism of the oxidation of dimethyl sulphoxide with bromine in aqueous solution

The kinetics and mechanism of the oxidation of dimethyl sulphoxide to dimethyl sulphone with bromine have been investigated. The reaction is first order in both bromine and dimethyl sulphoxide and is catalysed by acetate ions. These results, together with the observed rate reduction in the presence of bromide ion are consistent with the rate-determining step in the oxidation being the hydrolysis of Me2BrSO formed in a pre-equilibrium reaction between bromine and Me2SO.

Variations in the Composition of Bromine Water During Oxidation Reactions

AbstractA cubic equation has been derived that permits calculation of the composition of aqueous bromine solutions in terms of HOBr, BrO−, Br2, Br−3 and Br− as a continuous function of the pH, the initial oxidant concentration and the mole fraction of oxidant consumed. The calculations were performed by computer for the pH range 0–14 at bromine concentrations (c0) of 10−1 to 10−7 M. Throughout the course of an oxidation at pH 0 and c0= 10−4, bromine water is pure Br2. No Br−3 exists at c0 &lt; 10−3. In the pH range 4–6, dilute bromine solutions are pure HOBr (+ equimolar Br−). For pH &gt; 10, bromine water is pure BrO−, while at pH &lt; 7, no BrO− is present. These conditions are unchanged during oxidant consumption.

Kinetics of the oxidation of vanadium(III) by bromine in aqueous solutions

The reaction of 2V3++ Br2+ 2H2O → 2VO2++ 2Br–+ 4H+ obeys the rate expression –d[VIII]/dt=k′[VIII][Br2][H+]–1 with k′= 4·57 ± 0·44 s–1, Ea= 63·6 ± 2·9 kJ mol–1 and ΔS‡=–38·1 ± 7J mol–1 K–1 at 25 °C and ionic strength, µ= 2·0M. V3+ Therefore reacts with Br2 at a negligible rate compared with that of VOH2+. Added chloride ion enhances the rate of the reaction while bromide decreases it.

Bromine and Bromamine Disinfection Chemistry

The chemistry of bromine as a water disinfectant is analyzed. A logarithmic pH versus bromine-ammonia mole ratio distribution diagram for bromine and the bromamines is presented for 10 -4 M aqueous bromine solutions. Ultraviolet absorption spectra were used to identify the principal bromamine species initially formed as well as to follow the apparent second and third order decomposition of dibromamine and tribromamine, respectively. In the neutral pH range, tribromamine forms in solutions with mole ratios of ammonia to bromine less than 2:3 while dibromamine occurs at ratios greater than 2:3. A mechanism is proposed which accounts for the rapid rates of decomposition between dibromamine and tribromamine in the breakpoint region. Known variations of sporicidal and virucidal efficiencies as a function of pH, time and ammonia to bromine ratios are correlated with changes in the chemical species in solution.

Standardisation of dilute aqueous bromine solutions for reaction kinetics by incremental potentiometric titration with thiosulphate

Aqueous bromine in the concentration range 10 -1–10 -6 M oxidizes thiosulphate quantitatively to sulphate. This reaction can be used to standardise very dilute bromine solutions by addition of a measured but insufficient quantity of relatively concentrated standard thiosulphate solution. The fall in bromine-bromide redox potential at an inert indicator electrode caused by the addition allows the final bromine concentration to be found. The method can be applied in the measurement of fast bromination kinetics.

Reactions of β-keto-enol ethers with bromine in aqueous solution

The β-keto-enol ethers acetylacetone enol methyl ether, dimedone enol methyl ether, and 2,3-dihydro-2,6-dimethyl-γ-pyrone undergo fast olefinic addition reactions with aqueous bromine. Rate measurements for the last two are correlated with published data for olefins and enols. The bromination products of the first two, but not those of the last one, undergo slow, acid-catalysed fission of the méthoxy-group to give the bromo-enol.