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The bistability of the cerium-bromate-bromide system in an open-flow (CSTR) system was investigated near the critical point.Near this critical point Hopf's bifurcation occurs, causing stable states to become unstable.Domains of single or three unstable steady states occur, with possible oscillations around them.A good agreement is obtained between the calculated and experimental oscillation domains on the various subspaces of constraints.This oscillator is the simplest chemical oscillator fully understood in terms of elementary reactions.

To better define the mechanisms by which condensed-phase halides may be oxidized to form gas-phase halogens under polar conditions, experiments have been conducted whereby frozen solutions containing chloride (1 M), bromide (1.6 × 10-3 to 5 × 10-2 M), iodide (-5 M), and nitrate (0.01 to 1 M) have been illuminated by ultraviolet light in a continually flushed cell. Gas-phase products are quantified using chemical ionization mass spectrometry, and experiments were conducted at both 248 and 263 K. Br2 was the dominant product, along with smaller yields of IBr and trace BrCl and I2. The Br2 yields were largely independent of the Br-Cl- ratio of the frozen solution, down to seawater composition. However, the yields of halogens were strongly dependent on the levels of NO3- and acidity in solution, consistent with a mechanism whereby NO3- photolysis yields OH that oxidizes the condensed-phase halides. In support, we observed the formation of gas-phase NO2, formed simultaneously with OH. Gas-phase HONO was also observed, suggesting that halide oxidation by HONO in the condensed phase may also occur to some degree. By measuring the production rate of condensed-phase OH, using benzoic acid as a radical trap, we determine that the molar yield of Br2 formation relative to OH generation is 0.6, consistent with each OH being involved in halide oxidation. These studies suggest that gas-phase halogen formation should occur simultaneously with NOx release from frozen sea ice and snow surfaces that contain sufficient halides and deposited nitrate.

The oscillatory features of a new type Belousov-Zhabotin-skii oscillator with a macrocyclic copper(II) complex [CuL](ClO4)2 as catalyst and lactic acid as the substrate have been reported. This complex contains the ligand 5,7,12,14-tetraethyl-7,14-dimethyl-1,4,8,11 -tetraazacyclotetradeca-4,11-diene. A tentative mechanism based on FKN has been suggested. Copyright

The CCl3+ and CBr3+ cations have been synthesized by oxidation of a halide ligand of CCl4 and CBr4 at -78 °C in SO2ClF solvent by use of [XeOTeF5][Sb(OTeF5)6]. The CBr3 + cation reacts further with BrOTeF5 to give CBr(OTeF 5)2+, C(OTeF5)3 +, and Br2. The [XeOTeF5][Sb(OTeF 5)6] salt was also found to react with BrOTeF5 in SO2ClF solvent at -78 °C to give the Br(OTeF5) 2+ cation. The CCl3+, CBr 3+, CBr(OTeF5)2+, C(OTeF5)3+, and Br(OTeF5) 2+ cations and C(OTeF5)4 have been characterized in SO2ClF solution by 13C and/or 19F NMR spectroscopy at -78 °C. The X-ray crystal structures of the CCl3+, CBr3+, and C(OTeF 5)3+ cations have been determined in [CCl 3][Sb(OTeF5)6], [CBr3][Sb(OTeF 5)6]·SO2ClF, and [C(OTeF 5)3][Sb(OTeF5)6]·3SO 2ClF at -173 °C. The CCl3+ and CBr 3+ salts were stable at room temperature, whereas the CBrn(OTeF5)3-n+ salts were stable at 0 °C for several hours. The cations were found to be trigonal planar about carbon, with the CCl3+ and CBr3 + cations showing no significant interactions between their carbon atoms and the fluorine atoms of the Sb(OTeF5)6 - anions. In constrast, the C(OTeF5)3 + cation interacts with an oxygen of each of two SO2ClF molecules by coordination along the three-fold axis of the cation. The solid-state Raman spectra of the Sb(OTeF5)6- salts of CCl3+ and CBr3+ have been obtained and assigned with the aid of electronic structure calculations. The CCl3+ cation displays a well-resolved 35Cl/37Cl isotopic pattern for the symmetric CCl 3 stretch. The energy-minimized geometries, natural charges, and natural bond orders of the CCl3+, CBr3 +, Cl3+, and C(OTeF5) 3+ cations and of the presently unknown CF 3+ cation have been calculated using HF and MP2 methods have been compared with those of the isoelectronic BX3 molecules (X = F, Cl, Br, I, and OTeF5). The 13C and 11B chemical shifts for CX3+ (X = Cl, Br, I) and BX 3 (X = F, Cl, Br, I) were calculated by the GIAO method, and their trends were assessed in terms of paramagnetic contributions and spin-orbit coupling.

Making a quick recovery: The widespread implementation of bromination reactions to manufacture value-added products is contingent upon the development of sustainable and cost-effective means to recycle copious amounts of HBr byproduct. We report families of heterogeneous catalysts for the full recovery of Br2 through HBr oxidation that display unprecedented low-temperature activity and stability. Copyright

A new analytical method was developed for the determination of ascorbic acid in fruit juice and pharmaceuticals. The method is based on its inhibition effect on the reaction between hydrochloric acid and bromate. The decolourisation of Methyl Orange by the reaction products was used to monitor the reaction spectrophotometrically at 510 nm. The linearity range of the calibration graph depends on bromate concentration. The variable affecting the rate of the reaction was investigated. The method is simple, rapid, relatively sensitive and precise. The limit of detection is 7.6 × 10-6 M and calibration rang is 8 × 10-6-1.2 × 10-3 M ascorbic acid. The relative standard deviation of seven replication determinations of 8 × 10-6 and 2 × 10-5 M ascorbic acid was 2.8 and 1.7%, respectively. The influence of potential interfering substance was studied. The method was successfully applied for the determination of ascorbic acid in pharmaceuticals.

The oscillatory reaction between potassium bromate and gallic acid (in presence of sulfuric acid and ferroin indicator) has been calorimetrically and potentiometrically studied in binary mixtures of water and organic solvents viz. dimethyl formamide, acetonitrile, tetrahydrofuran and 1,4-dioxan. The effects of solvent polarity, stirring condition, indicator concentration, aerial oxygen and chloride ion on the oscillatory process have been examined. The oscillatory behaviour of the reaction probed by the potentiometric method has a general agreement with the calorimetric method. An attempt has been made to determine the order of the Fe2+Fe3+ oxidation reaction. The damping coefficients of the oscillatory process in aqueous and mixed solvent media have been estimated. by Oldenbourg Wissenschaftsverlag, Muenchen.

Complex periodic and aperiodic behaviours are reported in an unstirred Belousov-Zhabotinsky oscillatory reaction performed at temperatures varying between 0°C and 8°C. A route to chaos following a Ruelle-Takens-Newhouse (RTN) scenario is identified. Thus, temperature effects on the coupling between chemical kinetics, diffusion and convection, seem to be responsible for the observed RTN scenario. In this Letter we demonstrate that the temperature is a bifurcation parameter for the sequence period-1 → quasiperiodicity → chaos.

The oscillatory features of a novel type B-Z type oscillator, fructose [F] + oxalic acid [OA] + Ce4+ + BrO3- + H2SO4 has been investigated. The induction time is found to be usually small or negligible. Both single frequency oscillations and two oscillatory states separated by a time-pause are observed. Oscillations occur between two critical limits of [F] and [OA]. A tentative mechanism has been suggested which involves both Br- ion control and free radical control. Computer simulation correctly predicts some of the oscillatory features such as (i) time of initiation, (ii) critical limits of [OA] and (iii) stoppage of oscillations by higher [Br-], confirming the primary role of Br- control mechanism.

An electrochemical method for dispersion of single-walled carbon nanotubes (SWNTs) is described. The technique is based on grafting of oxygen-containing functional groups to the nanotube surface during electrolysis in aqueous and nonaqueous potassium bromide solutions. A dependence of the degree of functionalization of nanotubes on the solvent was revealed experimentally. Nanotubes treated in DMSO have about 14 carbon atoms per oxygen atom from functional groups (cf. nearly four C atoms per oxygen atom in the nanotubes treated in aqueous solutions). The corresponding maximum specific capacities of the electrodes are nearly 10 and 60 F g-1. The samples treated in solutions of KBr in DMSO have about 300 carbon atoms per bromine atom on the nanotube surface (cf. only 30 carbon atoms in the samples treated in aqueous solution). A mechanism of electrochemical modification of SWNTs is proposed. Its key step is production of atomic oxygen that oxidizes the nanotube surface with the formation of functional groups.

By using high surface area (roughness factor ca. 200) polycrystalline anatase films together with tris(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II), RuL34-, as a sensitizer, we have achieved unprecedentedly high visible light to electric current conversion efficiencies in regenerative photoelectrochemical cells.Incident photon to current conversion efficiencies of 73percent have been obtained at the wavelength of maximum absorption of the dye in the presence of iodide as an electron donor.Bromide is oxidized under the same conditions with an efficiency of 56percent.A regenerative cell based on the Br2/Br1- redox system gives a monochromatic light to power conversion efficiency of 12percent with a fill factor of 74percent.Preliminary results with polychromatic illumination are also presented.

The reaction between bromate and thiourea in acidic medium (HClO4) has been studied in a closed system and in a continuously stirred tank reactor (CSTR).The stoichiometry of the reaction at pH less than 2 has been deduced to be 8 BrO3(-) + 5 CS(NH2)2 + 8 H(+) + 6 H2O -> 4 Br2 + 5 (NH4)2SO4 + 5 CO2.In closed systems the reaction is characterized by an induction period whose length is inversely proportional to the initial concentrations of both acid and bromate.The induction period is followed by production of molecular bromine.In the CSTR the reaction displays sustained simple periodic oscillations in the bromine concentrations and the redox potential.No bistability was observed in the system.

Discharge flow/mass spectrometry has been used to measure the rate coefficient for the disproportionation reaction of BrO radicals, BrO + BrO -> products, at 2-Torr total pressure and over the temperature range 253-400 K.The value of k1 was fou

In reverse micelle systems, a large enhancement of the oxidation ability of dilute nitric acid was discovered, and its oxidation mechanism was explored. The Br- ion in the surfactant, CTAB, was oxidized to Br2 (or Br3-) in the CHCl3/CTAB/H2O reverse micelle system with W 1/4 1:0{4:0 by diluted nitric acid (0.25-2.5 mol dm-3 in 1.0 vol% H2O portion) at 15-40°C where CTAB stands for cetyltrimethylammonium bromide, and the W value is the ratio of [H2O]/ [surfactant]. At higher concentrations of nitric acid and temperatures, faster reactions occurred. Otherwise, long reaction times were needed, e.g., 10 h for 1.0 mol dm-3 HNO3 at 25°C. Light or ambient oxygen did not appear to affect the reaction. The ratio of produced Br2 or (Br3-) to the initial amount of HNO3 indicated the following reaction scheme: 2HNO3 + 2Br- → Br2 + NO2- + NO 3- + H2O. The nitroyl ion (or nitronium ion), NO2+, was proposed as the intermediate active species. The addition of HClO4 as a proton source caused the complete reduction of N(V) as follows: NO3- + 6H+ + 5e- → 1/2N2 + 3H2O. The hydrogen-bonding structure of H2O in the CTAB or CTAC (cetyltrimethylammonium chloride) micelle system was found to be distorted, compared to that in bulk water, by the 1H NMR chemical shift of H2O. The change in 1H NMR chemical shift also demonstrated the consumption of protons during the oxidation of Br-, but not of Cl-, by dilute HNO3.

Irradiation of oxygen-swept aqueous HBr solutions in the presence of catalytic amounts of anthraquinone derivatives (e.g. 2-sulphonate) produces molecular bromine (up to 3 mmol h-1) with quantum yields of up to 0.07.

A novel flah photolysis/kinetic absorption spectroscopy system has been constructed for the study of gas phase reactions.The experiment incorporates a charge-coupled device (CCD) detector and represents the first application of such devices to the study of gas phase kinetics.The CCD enables the recording of rapid sequential time-resolved UV/visible absorption spectra before, during, and after photolysis of a gas mixture.The unequivocal identification and monitoring of several absorbing components in the reacting mixture is therefore possible, therby maximizing the amount of information gathered from a single flash photolysis experiment.The experimental system is described in full here.Results from a preliminary kinetic study of the BrO self-reaction at 298 K are also described: BrO + BrO -> 2Br + O2 (1a); BrO + BrO -> Br2 + O2 (1b).Experiments were performed to independently determine the rates of the overall reaction, k1, defined by (-d/dt = 2k12) and both individual reaction channels (1a) and (1b), giving k1 = (2.98 +/- 0.42)E-12 cm3 molecule s-1; k1a = (2.49 +/- 0.42)E-12 cm3 molecule-1 s-1; and k1b = (4.69 +/- 0.68)E-13 cm3 molecule-1 s-1 at 298 K and 760 Torr total pressure in oxygen bath gas.Errors are 2?.Deviations from the expected second-order kinetic scheme were observed in the experimental system wherein bromine was photolyzed in the presence of excess ozone as a source of the BrO radicals.At low ozone concentrations, the formation of Br2O is proposed, and at very high ozone concentrations the formation of symmetric bromine dioxide, OBrO, is observed.Kinetic schemes for these side reactions have been deduced, and the mechanistic implications of these results are discussed.

Significant production of elemental bromine (Br2) was observed for the first time when treating bromide containing solutions at acidic pH, with TiO2photocatalyst, ozone, or a combination thereof. Br2selectivities up to approximately 85 % were obtained and the corresponding bromine mass balance values satisfied. The process is general and may be applied at a laboratory scale for green bromination reactions, or industrially as a cheap, safe, and environmentally sustainable alternative to the currently applied bromine production methods.

This study reports the first laboratory measurement of gas-phase Br 2 production from the reaction between gas-phase hydroxyl radicals and aqueous salt solutions. Experiments were conducted at 269 K in a rotating wetted-wall flow tube coupled to a chemical-ionization mass spectrometer for analysis of gas-phase components. From both pure NaBr solutions and mixed NaCl/NaBr solutions, the amount of Br2 released was found to increase with increasing acidity, whereas it was found to vary little with increasing concentration of bromide ions in the sample. For mixed NaCl/NaBr solutions, Br2 was formed preferentially over Cl2 unless the Br - levels in the solution were significantly depleted by OH oxidation, at which point Cl2 formation was observed. Presence of a surfactant in solution, sodium dodecyl sulfate, significantly suppressed the formation of Br2; this is the first indication that an organic surfactant can affect the rate of interfacial mass transfer of OH to an aqueous surface. The OH-mediated oxidation of bromide may serve as a source of active bromine in the troposphere and contribute to the subsequent destruction of ozone that proceeds in marine-influenced regions of the troposphere.

1:12-Silicomolybdic acid (SiMo12) doped carbon ceramic composite electrodes were fabricated by incorporating SiMo12 and graphite powder in a methyltrimethoxysilane-based gel and characterized by cyclic and square-wave voltammetry. It was demonstrated that the chemically modified electrodes were suitable for electrocatalytic reduction of bromate. The electrodes had the remarkable advantage of surface renewal owing to bulk modification, as well as simple preparation, good mechanical and chemical stability and reproducibility.

The oxidation of hydrogen bromide and alkali metal bromide salts to bromine in acetic acid by cobalt(III) acetate has been studied. The oxidation is inhibited by Mn(OAc)2 and Co(OAc)2, which lower the bromide concentration through complexation. Stability constants for CoIIBrn were redetermined in acetic acid containing 0.1% water as a function of temperature. This amount of water lowers the stability constant values as compared to glacial acetic acid. MnIIBrn. complexes were identified by UV-visible spectroscopy, and the stability constants for MnIIBrn were determined by electrochemical methods. The kinetics of HBr oxidation shows that there is a new pathway in the presence of MnIIBrn. Analysis of the concentration dependences shows that CoBr2 and MnBr2 are the principal and perhaps sole forms of the divalent metals that react with Co(III) and Mn(III). The interpretation of these data is in terms of this step (M, N = Mn or Co): M(OAc)3 + NIIBr2 + HOAc → M(OAc)2 + NIIIBr2OAc. The second-order rate constants (L mol-1 s-1) for different M, N pairs in glacial acetic acid are 4.8 (Co, Co at 40 °C), 0.96 (Mn, Co at 20 °C), 0.15 (Mn(III)·Co(II), Co at 20 °C), and 0.07 (Mn, Mn at 20 °C). Following that, reductive elimination of the dibromide radical is proposed to occur: NIIIBr2OAc + HOAc → N(OAc)2 + HBr2·. This finding implicates the dibromide radical as a key intermediate in this chemistry, and indeed in the cobaltbromide catalyzed autoxidation of methylarenes, for which some form of zerovalent bromine has been identified. The selectivity for CoBr2 and MnBr2 is consistent with a pathway that forms this radical rather than bromine atoms which are at a considerably higher Gibbs energy. Mn(OAc)3 oxidizes PhCH2Br, k = 1.3 L mol-1 s-1 at 50.0 °C in HOAc.

The activation parameters (ΔH(excit.), ΔS(excit.), ΔV(excit.)) for the co-ordination of hydrogen peroxide to methylrhenium trioxide have been determined.They indicate a mechanism involving nucleophilic attack.The protons lost in converting H2O2 to a co-ordinated η2-O2(2-) group are transferred to one oxide oxygen, which remains on the metal as an aqua ligand.The rate of reaction is not pH dependent, consistent with the deuterium kinetic isotope effect (kH/kD = 2.8).The method used to study the reaction is based on the ability of ReMeO3 to catalyse the reaction between Br(1-) and H2O2.The activation parameters for the uncatalysed reaction of Br(1-) and H2O2 were also determined.The value found for ΔV(excit.) is consistent with the accepted mechanism, proton-assisted nucleophilic displacement.

A simple, rapid, selective and highly sensitive spectrophotometric method is described for the quantitative determination of the tricyclic antidepressant drugs, desipramine hydrochloride (DPH), clomipramine hydrochloride (CPH) and imipramine hydrochloride (IMH) in pure and in pharmaceutical preparations. The proposed method is based on the bromination of above drugs with known excess of bromine. The unreacted bromine is determined based on its ability to bleach the dye Eiochrome blue black R quantitatively at 530 nm for all the three drugs obeying Beer's law in the range, 0.0-8, 0.0-10 and 0.0-9.0 μg ml-1 for DPH, CPH and IMH, respectively. The molar absorptivity values were found to be 1.61 × 104, 1.62 × 104 and1.57 × 104 l mol-1cm-1, respectively with the corresponding Sandell's sensitivity values 0.0187, 0.0216 and 0.0202 μg cm-2. The limits of detection and (LOD) and quantification (LOQ) are also reported for the developed method. Intra- and inter-day precision and accuracy of the method were established according to the current ICH guidelines. Applications of the procedure to the analysis of various pharmaceutical preparations gave reproducible and accurate results. Further, the validity of the procedure was confirmed by applying the standard addition technique and the results were evaluated in terms of Student's t-test and variance ratio F-test to find out the significance of proposed method over the reference method.

Electro-oxidation of Br- on platinum and gold electrode was studied in acetonitrile, methanol and mix media of acetonitrile-methanol. The mechanism of Br- oxidation in these media was investigated using CV, Semi Integration Cyclic Vo

Bromination of tris- and tetrakis-trifluoromethylated gallium corroles (3CF3?Ga and 4CF3?Ga) afforded tetrabrominated species 3CF3?4Br?Ga and 4CF3?4Br?Ga (yields: 20 % and 25 %) characterized by NMR, UV-vis spectroscopy, and mass spectrometry. Red-shifted absorption and emission bands were found; 3CF3?4Br?Ga and 4CF3?4Br?Ga displayed 5–12 nm shifts in their Soret bands and 8–17 nm shifts for their Q bands, compared to the respective nonbrominated species (3CF3?Ga and 4CF3?Ga). The respective ΦF values were found to be 0.013 and 0.016; phosphorescence (lifetime=0.23 μs) was observed for 3CF3?4Br?Ga (anaerobic, RT). The effect of tetrabromination on redox potentials (0.89 and 0.99 V) gave a 85 mV shift per Br atom in the reduction potential. 4CF3?4Br?Ga allows for efficient catalytic photooxidative Br? to Br2 conversion compared to the β-octa-Br system (Br8?Ga) structurally characterized here. This “hetero-multifunctionalization” approach, that is, is substitution with different sets of β-substituents, can help optimize porphyrinoid properties.

Treatment of olefinic amides with N-bromosuccinimide (NBS) in water is reported. Monobromobenzoxazines were mainly formed at room temperature, while at 80? °C multibromobenzoxazines were preferentially generated. Mechanism studies showed that the reaction might proceed via a cascade of electrophilic addition at the C=C bond followed by electrophilic substitution at the aromatic ring. No additives are required in this protocol.

A bromo-capped metal-metal bonded diruthenium(i,i) complex Ru2(CO)4(PIN)2Br2 (1) (PIN = 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene) generates bromine with N-bromosuccinimide (NBS) at room temperature. Cycloalkene and stilbene are readily brominated by stoichiometric reactions with 1 and NBS. An analysis of the dibrominated products suggests the formation of cyclic bromonium intermediates indicating in situ Br2 generation. Complex 2, an iodide analogue of 1, is also synthesized. The reaction of 2 with N-iodosuccinimide releases I2, which is confirmed by the starch-iodine test. The catalytic utility of 1 is examined for the bromination of phenol. Catalyst 1, in combination with NBS and base, exhibits regioselectivity towards monobrominated products. Furthermore, efficient olefin aziridination is demonstrated utilizing catalyst 1 in the presence of NBS, K2CO3 and TsNH2.

A Cr8 metallacrown binds halogens X2 (Cl2, Br2 and I2) without loss of crystallinity; the binding has been studied by X-ray diffraction and thermodynamic techniques.

Six ruthenium complexes, [Ru(bpy)3]2+ (1), [Ru(bpy)2(deeb)]2+ (2), [Ru(deeb)2(dmbpy)]2+ (3), [Ru(deeb)2(bpy)]2+ (4), [Ru(deeb)3]2+ (5), and [Ru(deeb)2(bpz)] 2+ (6) (bpy: 2,2′-bipyridine; deeb: 4,4′-diethylester-2,2′-bipyridine; dmbpy: 4,4′-dimethyl-2,2′-bipyridine, bpz: 2,2′-bipyrazine), have been employed to sensitize photochemical oxidation of bromide to bromine. The oxidation potential for complexes 1-6 are 1.26, 1.36, 1.42, 1.46, 1.56, and 1.66 V vs SCE, respectively. The bimolecular rate constants for the quenching of complexes 1-6 by ArN2+ (bromobenzenediazonium) are determined as 1.1 × 109, 1.6 × 108, 1.4 × 108, 1.2 × 108, 6.4 × 107, and 8.9 × 106 M-1 s-1, respectively. Transient kinetics indicated that Br- reacted with photogenerated Ru(III) species at different rates. Bimolecular rate constants for the oxidation of Br- by the Ru(III) species derived from complexes 1-5 are observed as 1.2 × 108, 1.3 × 109, 4.0 × 109, 4.8 × 109, and 1.1 × 1010, M-1 s-1, respectively. The last reaction kinetics observed in the three-component system consisting of a Ru sensitizer, quencher, and bromide is shown to be independent of the Ru sensitizer. The final product was identified as bromine by its reaction with hexene. The last reaction kinetics is assigned to the disproportionation reaction of Br2-? ions, for which the rate constant is determined as 5 × 109 M-1 s-1. Though complex 6 has the highest oxidation potential in the Ru(II)/Ru(III) couple, its excited state fails to react with ArN2+ sufficiently for subsequent reactions. The Ru(III) species derived from complex 1 reacts with Br- at the slowest rate. Complexes 2-5 are excellent photosensitizers to drive photooxidation of bromide to bromine.

A continuous-flow process for the in situ on-demand generation of cyanogen bromide (BrCN) from bromine and potassium cyanide that makes use of membrane-separation technology is described. In order to circumvent the handling, storage, and transportation of elemental bromine, a continuous bromine generator using bromate–bromide synproportionation can optionally be attached upstream. Monitoring and quantification of BrCN generation was enabled through the implementation of in-line FTIR technology. With the Br2 and BrCN generators connected in series, 0.2 mmol BrCN per minute was produced, which corresponds to a 0.8 m solution of BrCN in dichloromethane. The modular Br2/BrCN generator was employed for the synthesis of a diverse set of biologically relevant five- and six-membered cyclic amidines and guanidines. The set-up can either be operated in a fully integrated continuous format or, where reactive crystallization is beneficial, in semi-batch mode.

Methods and apparatus for generation of dual biocides are provided. The electrolytic generation of chlorine as a biocide is employed for further generation of additional biocides within a single system or generator, including bromine, iodine, chlorine dioxide, fluorine, or chloramines from their respective salts and/or precursors. A single on-site generating system produces a combination of biocides for applications of use providing cost, safety and efficacy improvements. Methods of using the disinfecting biocides provide a synergistic effect through simultaneous or sequential applications.

An embodiment relates to a process for converting lower molecular weight, gaseous alkanes to higher hydrocarbons, such as olefins, higher molecular weight hydrocarbons, or mixtures thereof, that may use in-line hydrogen bromide oxidation for capture of hydrogen bromide produced in the process. An embodiment may provide a process for producing elemental halogen comprising: providing a first stream comprising a hydrogen halide; contacting the first stream with a metal oxide to form water, elemental halogen, and at least some metal halide, wherein the metal oxide comprises a metal capable of forming a plurality of stable oxidation states; and contacting the metal halide with an oxygen source to produce a regenerated metal oxide, wherein the oxygen source contacts the metal halide under conditions sufficient to avoid release of elemental halogen.

Rutile TiO2 is a heavily investigated oxide with, to date, scarce applications in industrial catalysis. The inactivity of this material in oxidations has been related to its inability to dissociate molecular oxygen. Herein we show how rutile catalyzes the oxidation of HBr to Br2 through defect states that are introduced during the reaction. The identification of active, stable, and abundant materials for bromine production is key to the future implementation of Br2-mediated alkane functionalization processes. The catalytic properties of TiO2 are discussed in comparison to expensive rutile-type oxides, such as RuO2 and IrO2, on the basis of surface characterization and molecular modeling.

The aqueous photoreactions of three halide ions (chloride, bromide and iodide) were studied using a diode array spectrophotometer to drive and detect the process at the same time. The concentration and pH dependences of the halogen formation rates were studied in detail. The experimental data were interpreted by improving earlier models where the cage complex of a halogen atom and an electron has a central role. The triiodide ion was shown to exert a strong inhibiting effect on the reaction sequence leading to its own formation. An assumed chemical reaction between the triiodide ion and the cage complex interpreted the strong autoinhibition effect. It is shown that there is a real danger of unwanted interference from the photoreactions of halide ions when halide salts are used as supporting electrolytes in spectrophotometric experiments using a relatively high intensity UV light source.

Pt(IV) complexes trans-Pt(PEt3)2(R)(Br)3 (R = Br, aryl and polycyclic aromatic fragments) photoeliminate molecular bromine with quantum yields as high as 82%. Photoelimination occurs both in the solid state and in solution. Calorimetry measurements and DFT calculations (PMe3 analogs) indicate endothermic and endergonic photoeliminations with free energies from 2 to 22 kcal/mol of Br2. Solution trapping experiments with high concentrations of 2,3-dimethyl-2-butene suggest a radical-like excited state precursor to bromine elimination.

A new practical and efficient synthetic route for the synthesis of olopatadine hydrochloride via the intramolecular stereospecific seven-membered ring cyclization from an alkyne intermediate using palladium catalyst and hydride source was established. Furthermore, the optimization of that key stereospecific reaction was examined by design of experiment (DoE), and the desired Z-isomer could be obtained with high yield.

In summary, an easily accessible class of highly potent bis(pyridinium)-based multidentate XB donors has been introduced, which, in addition to their inherent XB acidity, also include a built-in redox option. In the previously established benchmark reaction to test the carbon-bromine bond-activation potential of XB donors, these compounds (2a, 2a', and 2b) are slightly more effective than bis(imidazolium)- based XB donors. Initially, the analysis of the overall process was complicated by the oxidation of bromide to elemental bromine by the azobis(halopyridinium) compounds during the reaction. The bromine thus formed was part of an additional activation process, which could, however, be suppressed by addition of cyclohexene. Two directions will be pursued in future work: since we demonstrated the activation capabilities of pyridinium-based XB donors towards carbon-bromine bonds, we plan to develop other types of activating reagents with redox-innocent bridging motives. Parallel to this, we strive to exploit the coupled oxidation/ XB-activation potential of the activators presented herein in suitable reactions.

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.

A method is provided for converting hydrogen bromide to elemental bromine. A portion of an initial hydrogen bromide-rich gas is thermally oxidized at a thermal oxidation temperature to produce a first fraction of elemental bromine and a remainder of the initial hydrogen bromide-rich gas. At least a portion of the remainder of the initial hydrogen bromide-rich gas is catalytically oxidized at a lower catalytic oxidation temperature to produce a second fraction of elemental bromine.

The electrolytic oxidation of HBr was investigated using molten alkali-bromide salts in a porous scaffold of yttria-stabilized zirconia (YSZ), with porous Pt electrodes. Despite a relatively thick (1.0 mm) and dense (35% porous) YSZ scaffold, a total cell impedance of less than 3 Ωcm 2 was achieved with NaBr at 1033 K. The open-circuit potentials also agreed with theoretical potentials for the reaction H2 + Br 2 = 2HBr. Lower operating temperatures were made possible by using a eutectic mixture of alkali bromides, (Li0.56K0.19Cs 0.25)Br. The electrolyte losses for the (Li0.56K 0.19Cs0.25)Br electrolyte, determined from the ohmic component of the impedance spectra, were less than 1.5 Ωcm2 at 673 and 773 K, similar to the value found for NaBr at 1033 K, indicating that the ionic conductivities of the alkali bromides are high so long as the salts are molten. However, the electrode losses were dependent on temperature, decreasing from 18.1 Ωcm2 to 3.0 Ωcm2 in going from 673 to 773 K. Implications of these results for recycling HBr in hydrocarbon bromination reactions are discussed.

A method comprising: providing a first halogen stream; providing a first alkane stream; reacting at least a portion of the first halogen stream with at least a portion of the first alkane stream in a first reaction vessel to form a first halogenated stream; providing a second alkane stream comprising C2 and higher hydrocarbons; providing a second halogen stream; and reacting at least a portion of the second halogen stream with at least a portion of the second alkane stream in a second reaction vessel to form a second halogenated stream.

An integrated process for producing aromatic hydrocarbons and ethylene and/or propylene and optionally other lower olefins from low molecular weight hydrocarbons, preferably methane, which comprises: (a) contacting at least one low molecular weight alkane, preferably methane, with a halogen, preferably bromine. under process conditions sufficient to produce a monohaloalkane, preferably monobromomethane, (b) reacting the monohaloalkane in the presence of a coupling catalyst to produce aromatic hydrocarbons and C2+ alkanes, (c) separating the aromatic hydrocarbons from the product mixture of step (b) to produce aromatic hydrocarbons, and (d) cracking at least part of the C2+ alkanes in an alkane cracking system to produce ethylene and/or propylene and optionally other lower olefins.

An integrated process for producing aromatic hydrocarbons and ethylene and/or propylene and optionally other lower olefins from low molecular weight hydrocarbons, preferably methane, which comprises: (a) contacting one or more low molecular weight alkanes, preferably methane, with a halogen, preferably bromine, under process conditions sufficient to produce a monohaloalkane, preferably monobromomethane, (b) reacting a first portion of the monohaloalkane in the presence of a coupling catalyst under process conditions sufficient to produce aromatic hydrocarbons and C2-5 alkanes, (c) separating the aromatic hydrocarbons from the product mixture of step (b) to produce aromatic hydrocarbons, (d) reacting a second portion of the monohaloalkane in the presence of a coupling catalyst under process conditions sufficient to produce ethylene and/or propylene.

Mn(iv) acetate was generated in acetic acid solutions and characterized by UV-vis spectroscopy, magnetic susceptibility, and chemical reactivity. All of the data are consistent with a mononuclear manganese(iv) species. Oxidation of several substrates was studied in glacial acetic acid (HOAc) and in 95 : 5 HOAc-H2O. The reaction with excess Mn(OAc)2 produces Mn(OAc)3 quantitatively with mixed second-order kinetics, k (25.0 °C) = 110 ± 4 M-1 s-1 in glacial acetic acid, and 149 ± 3 M-1 s-1 in 95% AcOH, ΔH ? = 55.0 ± 1.2 kJ mol-1, ΔS ? = -18.9 ± 4.1 J mol-1 K-1. Sodium bromide is oxidized to bromine with mixed second order kinetics in glacial acetic acid, k = 220 ± 3 M-1 s-1 at 25 °C. In 95% HOAc, saturation kinetics were observed. The Royal Society of Chemistry 2010.

(Chemical Equation Presented) Scanning electrochemical microscopy surface interrogation (SI-SECM) in the cyclic voltammetry mode was successfully used to detect and quantify adsorbed CO on a Pt electrode by reaction with electrogenerated Br2. T

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

The radiation chemical redox transformations in solutions of bromides in the presence of minor additives of iodides were studied by pulse radiolysis. The change in the concentrations of the Br- and I- ions changes the ratio of the formed short-lived radical anions Br2 ?-, BrI?-, and I2 ?-. The spectrum of the mixed radical anion BrI?- contains a broad optical band at 370 nm with 370 = 9650 L mol-1 cm -1. The reduction potential of the BrI?-/Br -, I- pair is 1.25 V. The rate constants for the forward and backward reactions Br2 ?- + I- BrI?- + Br- are k f = 4.3?10 9 and k r = 1.0?105 L mol-1 s-1, respectively; for the reactions BrI?- Br - + I?, k f = 5.7?108 s-1 and k r = 1.0?1010 L mol-1 s-1.

A solid composition for forming chlorine dioxide on demand and a sealed biocide article.

A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to study the recombination of mercury and bromine atoms, Hg + Br + M → HgBr + M (1) and the self- reaction of bromine atoms, Br + Br + M → Br2 + M (2). Rate coefficients were determined as a function of pressure (200-600 Torr) and temperature (243-293 K) in nitrogen buffer gas and as a function of pressure (200600 Torr) in helium buffer gas at room temperature. For reaction 1, kinetic measurements were performed under conditions in which bromine atoms were the reactant in excess concentration while simultaneously monitoring the concentration of both mercury and bromine. A temperature dependent expression of (1.46 ± 0.34) × 10 -32 × (T/298)-(1.86±1.49) cm6 molecule-2 s-1 was determined for the third-order recombination rate coefficient in nitrogen buffer gas. The effective second-order rate coefficient for reaction 1 under atmospheric conditions is a factor of 9 smaller than previously determined in a recently published relative rate study. For reaction 2 we obtain a temperature dependent expression of (4,31 ± 0.21) × 10-33 × (T/298)- (2.77±0.30) cm6 molecule-2 s -1 for the third-order recombination rate coefficient in nitrogen buffer gas. The rate coefficients are reported with a 2σ error of precision only; however, due to the uncertainty in the determination of absolute bromine atom concentrations and other unidentified systematic errors we conservatively estimate an uncertainty of ± 50% in the rate coefficients. For both reactions the observed pressure, temperature and buffer gas dependencies are consistent with the expected behavior for three-body recombination.

Disclosed herein is an improved method for regenerating materials from a desulfurization/demetallation reaction. The desulfurization/demetallation reaction preferably has products including one or more of an alkali sulfide, polysulfide or hydrosulfide, or alkali earth sulfide, polysulfide, or hydrosulfide. The method includes the steps of reacting the desulfurization/demetallation products with a halogen, liberating and removing sulfur from the product, and then electrolyzing the halogenated products to separate the halogen from the alkali metal or alkali earth metal.

Liquid and solid bromine-containing compositions are described. A liquid mixed halogen composition is also described. The highly concentrated liquid compositions and the high-activity solid compositions have excellent physical and chemical stability. The compositions are effective biocides in water treatment. Methods of preparing the compositions are also disclosed. These include combining a bromine compound in the oxidation state of -1 with hydrogen peroxide and a complexing agent followed by the addition of an alkaline source. The methods may further include the use of a solid organic or solid inorganic halogenating agent, conducting a solid-liquid separation, and adding an alkaline source.

Thermodynamic function values were refined for two independent chemical reactions in the gas phase of the Ge-Br system.

Oxygen atom transfer from trans-L(H2O)RhOOH2+ {L = [14]aneN4 (L1), meso-Me6[14]aneN4 (L2), and (NH3)4} to iodide takes place according to the rate law -d[L(H2O)RhOOH2+]/dt = k I[L(H2O)RhOOH2+][I-][H+]. At 0.10 M ionic strength and 25 °C, the rate constant kI/M -2 s-1 has values of 8.8 × 103 [L = (NH3)4], 536 (L1), and 530 (L2). The final products are LRh(H2O)23+ and I 2/I3-. The (NH3)4(H 2O)RhOOH2+/Br- reaction also exhibits mixed third-order kinetics with kBr ≈ 1.8 M-2 s-1 at high concentrations of acid (close to 1 M) and bromide (close to 0.1 M) and an ionic strength of 1.0 M. Under these conditions, Br2/Br 3- is produced in stoichiometric amounts. As the concentrations of acid and bromide decrease, the reaction begins to generate O2 at the expense of Br2, until the limit at which [H +] ≤ 0.10 M and [Br-] ≤ 0.010 M, when Br 2/Br3- is no longer observed and O2 is produced quantitatively. At this limit, the loss of (NH3) 4(H2O)RhOOH2+ is about twice as fast as it is at the high [H+] and [Br-] extreme, and the stoichiometry is 2(NH3)4(H2O)RhOOH2+ → 2(NH3)4(H2O)RhOH2+ + O2; i.e., the reaction has turned into the bromide-catalyzed disproportionation of coordinated hydroperoxide. In the proposed mechanism, the hydrolysis of the initially formed Br2 produces HOBr, the active oxidant for the second equivalent of (NH3)4(H2O)RhOOH2+. The rate constant kHOBr for the HOBr/(NH3) 4(H2O)RhOOH2+ reaction is 2.9 × 10 8 M-1 s-1.

A new procedure to produce the BrO2 transient species allowed time-resolved UV-vis spectra that show a structured band (λmax = 502 nm) in dichloromethane to be obtained. In water, because of the increase of the dielectric constant, the λmax presents a blue shift to 474 nm and the species decomposes much faster. The time-resolved spectra show evidence for its equilibrium with a nonidentified colorless form. This route opens new possibilities to the study this species in solution.

The initial rate of the bromate-bromide reaction, BrO3 - + 5Br- + 6H+ → 3Br2 + 3H 2O, has been measured at constant ionic strength, l = 3.0 mol L -1, and at several initial concentrations of acetate, bromate, bromide, and perchloric acid. The reaction was followed at the Br 2/Br3- isosbestic point (λ = 446 nm) by the stopped-flow technique. A very complex behavior was found such that the results could be fitted only by a six term rate law, v = k1[BrO 3-][Br-][H+]2 + k 2[BrO3-][Br-]2[H +]2 + k3[BrO3-][H +]2[acetate]2 + k4[BrO 3-][Br-]2[H+] 2[acetate] + k5[BrO3-][Br -][H+]3[acetate]2 + k 6[BrO3-][Br-][H+] 2[acetate], where k1 = 4.12 L3 mol-3 s -1, k2 = 0.810 L4 mol-4 s -1, k3 = 2.80 × 103 L4 mol-1 s-1, k4 = 278 L5 mol -5 s-1, k5 = 5.45 × 107 L 6 mol-6 s-1, and k6 = 850 L 4 Mol-4 s-1. A mechanism, based on elementary steps, is proposed to explain each term of the rate law. This mechanism considers that when acetate binds to bromate it facilitates its second protonation.

The character and kinetics of chemical dissolution have been investigated for cadmium telluride, undoped or doped with Ga, Ge, Sb, Sn, and (As + Cl), in solutions of the H2O2-HBr system. Dissolution rate versus concentration curves for the mentioned materials have been plotted at the content 2-50 vol % H2O2. The dopants affect the etching rate of CdTe and the quality of the treated surface, which should be taken into account in the development of polishing etchants. The concentration limits of solutions suitable for dynamic chemical polishing of the mentioned semiconductor structures have been determined.

Highly uniform γ-MnO2 3D urchinlike and sisallike nanostructures have been successfully prepared by a common hydrothermal method based on the reaction between MnSO4 and KBrO3. Reaction temperature and the additives of the polymers play an important role in influencing the morphologies of the as-obtained products. These urchinlike and sisallike nanostructures, which own the highly specific area on the surface of the particles may provide more possibility to give an ideal host material for the insertion and extraction of lithium ions, to realize region-dependent surface reactivity, and to act as molecular sieves.

The process parameters of dehydrogenation of pantolactone with bromine in chloroform and the possibility of bromine recycling by electrolysis of hydrogen bromide formed in the synthesis of ketopanto-lactone were studied.

Solvent and electrode kinetic effects on the anodic oxidation of Br --Br3--Br2 system involving Br -/Br3- and Br3-/Br 2 redox couples, have been studied on bare and platinized Pt and C surfaces by cyclic voltammetric (CV) measurements in some dipolar aportic solvents like acetonitrile, N,N-dimethylformamide and propylene carbonate and in water on bright Pt surface. The rate constants (ks) have been evaluated by Shain and Nicholson's formulations as appropriate to the irreversible and quasi-reversible CV waves observed in different cases. Kinetic solvent effects on both the redox reactions on Pt surface in different solvents have been analyzed in the light of initial and transition state (TS) solvation using the previously determined solvation free energies of Br-, Br3- and Br2 in the respective solvents. The observed ks values for both the redox couples reflect that the electrocatalytic activities of the electrodes are in the order C Pt ≤ (Pt) Pt (C)Pt. as are expected from the combined effects of geometric and electronic characters of the involved electrode surfaces.

The bromine-adsorption behavior of [Pd(chxn)2][PdBr2(chxn)2]Br4 (chxn: 1R,2R-cyclohexanediamine) has been investigated by elemental analysis, X-ray powder diffraction (XRD), 1H NMR and ESR. From XRD, the reaction of the palladium complex with bromine was revealed to be reversible depending on the partial pressure of bromine around the complex. Elemental analysis suggested the adsorption of two Br2 molecules per the formula unit. Temperature dependence of the ESR intensity showed the existence of Curie and thermally activated spins in both compounds with and without bromine-adsorption. The spin density, as well as the fraction of Curie spins, decreased after bromine-adsorption suggesting the oxidation of paramagnetic Pd(III) into Pd(IV). 1H NMR spin-lattice relaxation of these compounds is determined by the coupling with the thermally activated spins as well as with the Curie spins.

The uptake kinetics of HOBr on NaBr and NaCl particle-film surfaces has been studied in a flow reactor coupled with a differentially pumped quadrupole mass spectrometer. Spray-deposited and aerosol-deposited salt-particle films were used for the measurement of HOBr reactivity. A rapid gas-surface reaction was observed on the NaBr surface at 250 K, and the initial uptake coefficient ?3w was determined to be 0.029 ?± 0.004 and 0.021 ?± 0.004 at relative humidities (RH) of 0.5 and 12.2%, respectively. ?3w is lower at 260 K. For the reaction on NaCl particle surfaces, ?3w decreases slightly from 2.0 ?± 0.3 ?? 10-3 to 8.1 ?± 1.3 ?? 10-4 at 250 K as RH increases from 1.5 to 18.2%. The results are interpreted in terms of the mechanism HOBr(ad) + NaX(s) a?? BrX + NaOH(s), which involves the adsorption of HOBr on the surface, with the reactions occurring mainly on a NaX surface domain without water coverage at low RH. The surface morphology of the particle films was characterized by scanning electron microscopy, and the tortuosity factor, ??, of the NaCl particle film was determined to be 2.18.?3w was corrected for internal surface effects to provide true uptake coefficients ?3t. Typical ?3t values for HOBr on NaBr and NaCl at 250 K and RH of 10% are 2.5 ?? 10-3 and 5 ?? 10-5, respectively. Calculations suggest that the HOBr heterogeneous activation on NaBr may be competitive, if surface regeneration occurs.

The photodissociation of Br2CO at 267 nm was studied by ion velocity imaging and TOF-MS method. Bimodal kinetic energy distributions of bromine atoms were found. In general, the results indicate that the transition dipole moment of Br2/su

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.