Bromate Salts Research Articles

Halogen Bonding Assembles Anion···Anion Architectures in Non-centrosymmetric Iodate and Bromate Crystals.

Single crystal X-ray diffraction of iodate and bromate salts shows that the I and Br atoms in IO3- and BrO3- anions form short and linear O-I/Br···O contacts with the O atoms of nearby anions. Noncentrosymmetric systems are formed wherein anions are orderly aligned into supramolecular 1D and 2D networks. Theoretical evidences, namely the outcome of QTAIM and NCIplot studies, prove the attractive nature of these contacts and the ability of iodate and bromate anions to act as robust HaB donors. The HaB is proposed as a general and effective assisting tool to control the architecture of acentric iodate salts.

Buoyancy-Driven Chemohydrodynamic Patterns in A + B → Oscillator Two-Layer Stratifications

Chemohydrodynamic patterns due to the interplay of buoyancy-driven instabilities and reaction-diffusion patterns are studied experimentally in a vertical quasi-two-dimensional reactor in which two solutions A and B containing separate reactants of the oscillating Belousov-Zhabotinsky system are placed in contact along a horizontal contact line where excitable or oscillating dynamics can develop. Different types of buoyancy-driven instabilities are selectively induced in the reactive zone depending on the initial density jump between the two layers, controlled here by the bromate salt concentration. Starting from a less dense solution above a denser one, two possible differential diffusion instabilities are triggered depending on whether the fast diffusing sulfuric acid is in the upper or lower solution. Specifically, when the solution containing malonic acid and sulfuric acid is stratified above the one containing the slow-diffusing bromate salt, a diffusive layer convection (DLC) instability is observed with localized convective rolls around the interface. In that case, the reaction-diffusion wave patterns remain localized above the initial contact line, scarcely affected by the flow. If, on the contrary, sulfuric acid diffuses upward because it is initially dissolved in the lower layer, then a double-diffusion (DD) convective mode develops. This triggers fingers across the interface that mix the reactants such that oscillatory dynamics and rippled waves develop throughout the whole reactor. If the denser solution is put on top of the other one, then a fast developing Rayleigh-Taylor (RT) instability induces fast mixing of all reactants such that classical reaction-diffusion waves develop later on in the convectively mixed solutions.

Green process development for the preparation of 2,6-dibromo-4-nitroaniline from 4-nitroaniline using bromide–bromate salts in an aqueous acidic medium

Organic solvent-free process for the preparation of 2,6-dibromo-4-nitroaniline, from 4-nitroaniline using 2 : 1 bromide–bromate salts under aqueous acidic medium at ambient conditions has been developed.

Preparation and characterization of low environmental humidity sensitive ionic liquid polymer electrolytes

ABSTRACTMethyl 3‐(3‐(2‐hydroxyethyl)imidazole‐1‐yl)propanoate chloride salt (IL‐Cl), methyl 3‐(3‐(2‐hydroxyethyl)imidazole‐1‐yl)propanoate bromate salt (IL‐Br), and their derivatives modified by polyethylene glycol (PEG) through ester‐exchange reaction (IL‐PEGs) were synthesized. First, the properties of those materials, especially their conductivity, have been extensively studied. Second, using the IL‐PEG with the highest conductivity as a plasticizer and electrolyte, a series of gel polymer electrolytes were successfully fabricated from polyurethane, poly‐1,4‐butylene adipate glycol 2000, and IL‐PEGs by melting blends with different mass ratios in a Haake torque rheometer. The surface morphology, thermal properties, and the surface resistivity of gel polymer electrolytes were studied by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and surface resistivity test, respectively. Scanning electron microscopy pictures showed that the surface of polymer electrolyte is smoother than that without added IL‐PEGs. Thermogravimetric analysis results revealed that the polymer electrolytes will not decompose when the processing temperature is below 275°C. It was found that the surface resistivity of polymer electrolytes can be below 109 Ω, showing a good antistatic property, and it changes slightly as the relative humidity decreases from 40% to 0.1%, indicting that the material has low humidity sensitivity. This study is a new demonstration and development in ionic liquid based polymer electrolyte. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40675.

Re-evaluation of the Thermodynamic Activity Quantities in Pure Aqueous Solutions of Chlorate, Perchlorate, and Bromate Salts of Lithium, Sodium or Potassium Ions at 298.15 K

The Huckel equation used to correlate the experimental activities of dilute alkali metal chlorate, perchlorate or bromate solutions up to a molality of about 1.5 mol⋅kg−1 contains two electrolyte-dependent parameters: B {that is related closely to the ion-size parameter (a∗) in the Debye–Huckel equation} and b1 (this parameter is the coefficient of the linear term with respect to the molality, which is related to hydration numbers of the ions of the electrolyte). In more concentrated solutions up to 7 mol⋅kg−1, an extended Huckel equation was used, it contains additionally a quadratic term with respect to the molality, and the coefficient of this term is the parameter b2. Parameters for the Huckel equations were evaluated from isopiestic data for LiClO3, LiBrO3, LiClO4, NaClO3, NaBrO3, NaClO4, KClO3, and KBrO3. In these estimations, the Huckel parameters determined recently for NaCl solutions were used. The resulting parameter values were tested with the vapor pressure and isopiestic data available in the literature for solutions of these salts. Most of these data were reproduced within experimental error by means of the Huckel or extended Huckel equations, at least up to a molality of 3.0 mol⋅kg−1, for all salts considered. Reliable activity and osmotic coefficients for solutions of these salts can, therefore, be calculated by using the new Huckel equations, and they are tabulated here at rounded molalities. The activity and osmotic coefficients obtained from these equations were compared to the values reported in several previous tabulations.

Effects of liquid phase composition on salt cluster formation in positive ion mode electrospray mass spectrometry: implications for clustering mechanism in electrospray

Potassium bromate salt clusters, [KBrO 3] nK x x+, formed by electrospray ionization were studied as a function of solution properties. Clusters with up to 4 positive charges were observed. Their abundance, charge state and distribution were shown to vary with the organic solvent in solution. The effects of 7 solvents, including methanol, ethanol, isopropanol, acetonitrile, acetone, pyridine, and 1,4-dioxane, were thoroughly investigated. Solvents with a low dielectric constant and a high viscosity seem to favor clustering in solution but do not systematically allow high charge state ion formation. On the other hand, cluster charge reduction during desolvation was not correlated with solvent cation affinity over the range of solvents examined. However, ion distribution in mass spectra could be rationalized as a combination of these two competing phenomena. Charge state increases with the cluster size but may be reduced during ion desolvation when high cation affinity solvent molecules are actually involved in the ion solvation shell. This assumption could be envisaged in either Iribarne or Dole mechanisms of ion release in the gas phase. However, intensity profiles of multiply charged clusters could only be understood in terms of the ion evaporation mechanism.

Use of Sodium Bromate for Aromatic Bromination: Research and Development

Sodium bromate is a powerful brominating agent for aromatic compounds that contain deactivating substituents. A bromination process, in which sodium bromate was utilized, was optimized on laboratory scale. Addition of a strong acid into a stirred aqueous solution, or slurry, of the substrate and bromate salt at 40−100°C, leads to the decomposition of the bromate ions and production of the active brominating species. Substrates such as nitrobenzene, benzoic acid, and benzaldehyde were brominated in high yields (85−98%) and specificity. The reaction is especially useful for the bromination of disubstituted benzenes, such as 4-nitrofluorobenzene or 4-fluorobenzoic acid. Several substrates, such as dinitrobenzenes or nitrobenzoic acids, did not undergo bromination at all. The main parameters of the reaction and some of its synthetic potential are discussed.

Occurence and Control of Bromate in Aqueous Media

Bromate salt is an oxidizing agent that has been widely used as a food additive, but now the use of bromate is restricted to low level because of its mutagenicity and carcinogenicity. Potassium bromate was weakly mutagenic in Salmonella typhimurium TA100, TA102, and TA104 in the presence of metabolic activation, though the compound proved to be negative in TA98, TA1535, TA1537 and TA1538. It also demonstrated genotoxicity in some microbial tests. Potassium bromate or its radical derived from reduction seems to induce lipid peroxidation in producing oxidized DNA damage to the target. Bromate ion also exists in drinking water produced during ozonation of bromide-containing water. WHO guideline for drinking water quality recommended bromate concentration below 0.025mg/l and the U.S. government determined the maximum bromate concentration as 0.010mg/l in regulation, which leads the application of ozonation to be reconsidered. In Japan, 0.127mg/l of bromate ion was produced in experimental ozonation plant and the maximum of bromate ion (0.03mg/l) was detected in drinking water treatment plant. Bromate can be produced with water of high bromide concentration and must be controlled in treatment plant of high ozone dosage. New activated carbon reduces bromate though the activated carbon used for several months showed no reduction of bromate. Reduction of pH and ozone dose is most available technology for reducing bromate. Bromate is also detected in sodium hypochloride as a disinfectant and chlorinated water. Contaminated river water contained bromate up to 0.009mg/l, possibly discharged from permanent-wave neutralizing agent. Environmental bromide and bromate contamination should have a potential importance.

A Transferable Interatomic Potential for Alkali Chlorates and Bromates

Interatomic potential parameters obtained via empirical fitting techniques provide good agreement between predicted and experimentally derived structural parameters for a range of alkali chlorate and bromate salts, as well as a double chlorate/bromate salt. Examination of the transfer of these parameters to modelling the structural properties of the divalent salt strontium chlorate provided a reasonable, albeit poorer, reproduction of the experimental data. Calculated elastic constants for all materials are provided.

Selective cerium-catalyzed oxidation of alkyl benzenes to benzyl esters by bromate salts

Benzyl esters are formed catalytically at moderate temperatures from alkyl benzenes by KBrO 3 in the presence of cerium ammonium nitrate (CAN). Toluene gives in acetic acid benzyl acetate. Ethylbenzene, cumene, 4- tert-butyltoluene, and 4-bromotoluene give similar oxidation products. p-xylene undergoes a selective mono-acetoxylation reaction in acetic acid. The bromate salt is acting as an oxidant for the alkylbenzene and a cooxidant for the Ce salt. The Ce salts (Ce(III), Ce(IV)) serve both as oxidation catalysts and as Lewis acids that catalyze the conversion of benzyl bromide in the reaction mixture to benzyl ester.

ChemInform Abstract: Cerium‐Catalyzed Selective Oxidation of Alkylbenzenes with Bromate Salts.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Cerium-Catalyzed Selective Oxidation of Alkylbenzenes with Bromate Salts

Abstract Cerium(IV) ammonium nitrate (CAN)-catalyzed oxidation of alkyl aromatics with potassium bromate affords aldehydes, ketones acids or alcohols in high yields.

Magnetic shielding of23Na nuclei in NaNO3 and NaBrO3 single crystals

Single crystals of sodium nitrate, sodium chlorate and sodium bromate were investigated by continuous wave and Fourier transform pulse techniques. The sodium shielding tensors for studied compounds were found from the shift of the central line of23Na triplet, which was measured as a function of the crystal orientation. The shielding appears isotropic in NaNO3 and anisotropic in chlorate and bromate salts; the anisotropies are 0±2, 12±1 and 17±1 ppm respectively. It is suggested that lattice forces lowering the local symmetry at the sodium site are responsible for the observed effects of shielding anisotropy.