Simultaneous Determination of Micro Bromide and Iodide by Kinetic Spectrophotometric Method

ABSTRACT

ABSTRACTA new kinetic spectrophotometric method for the simultaneous determination of concentrations of micro bromide and iodide has been proposed. It is based on their catalytic effects on the reaction of m-cresol purple oxidized by potassium periodate in hydrochloride acid medium. The reaction rate was monitored by measuring the decrease in absorbance at 528nm and the increase in absorbance at 455nm. The total difference in absorbance of the sum of bromide and iodide is identical with determination of bromide was carried out after Cr(VI) oxidized I? to I₂, and I₂ was removed by extraction with CCI₄, and the amount of iodide was measured by subtracting the absorbance change of bromide from the total absorbance change in the presence of bromine and iodide. The optimum conditions influencing the reaction rate were studied. The linear range of determination is 0～4.0μg/ml for Br? and 0～3.0 μg/ml for I?. The detection limits are 0.032μg/ml for Br? and 0.059 μ/ml for I?. The method was successfully applied to the determination of micro amounts of bromide and iodide in food and life samples.     

Using ratiometric indicator-displacement assays in semi-quantitative colorimetric determination of chloride, bromide, and iodide anions

A ratiometric indicator-displacement assay (RIDA) array has been developed for the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions. Determinations of these halide anions follow the displacement reaction using the chelate compound of (2-(3,5-dibromo-2-pyridylazo)-5-(diethylamino)phenol) (3,5-Br2-PADAP) and heavy metal salts as colorimetric reagent. Different from regular silver nitrate titrations, the chloride, bromide, and iodide anions compete with the 3,5-Br2-PADAP ligand and change the colour of the 3,5-Br2-PADAP-metal chelate compound dramatically. These clearer colour changes make the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions possible. The colour changes are imaged using a conventional flatbed scanner, and digitized. After statistical analysis, these colour changes in the RIDA array provide facile identification of chloride, bromide, and iodide anions at a wide concentration range (10 μM to 10 mM) without any misclassification. The RIDA array is able to discriminate without misclassifications among seven concentrations of chloride, bromide, and iodide anions. No shelf life issue exists because the chelating compounds react with halide anions directly without any pre-immobilizations.     

Determination of iodide and bromide by ion chromatography with post-column reaction detection

During an investigation into the mechanism of the biosynthesis of thyroid hormones, it became necessary to determine traces of iodide and bromide in biological matrices as well as in food. A vydac 302-IC anion-exchange column with methanesulphonic acid as the mobile phase was used for the ion chromatographic separation of iodide and bromide. A post-column reaction detector was developed based on the reaction between iodide or bromide, chloramine-T and 4,4'-bis(dimethylamino)diphenylmethane. Methods with minimal sample preparation are described for determination of iodide or bromide in serum, milk, salt and water. The detection limit is ca. 20 pg iodide and 15 ng bromide injected.     

溴甲烷在强激光场中的电离和解离

利用自制的反射式飞行时间质谱仪(RTOF-MS)研究了多原子分子CH₃Br在强激光场中的电离解离. 得到了溴甲烷在强激光场中电离解离的飞行时间质谱, 基于RTOF-MS的高分辨率(M/ΔM>2000), 测量了分子库仑爆炸产生的系列碎片离子的动能释放(KER), 用多光子解离和库仑爆炸解释了实验结果. 与碘甲烷在强场中的实验结果对比发现: (1) 在相同的激光场强下, 碘甲烷电离解离的最高价碎片离子为I⁶⁺而溴甲烷为Br³⁺; (2) 溴甲烷质谱中存在母体离子的脱氢产物CH_mBr⁺ 和CH_mBr²⁺, 而对于碘甲烷, 没有检测到这些通道, C-I键首先断开; (3) 质谱中存在H⁷⁹Br⁺和H⁸¹Br⁺, 而碘甲烷的电离解离中不存在HI产物; (4) 溴甲烷库仑两体爆炸的有效电荷间距随着两碎片电荷乘积的增大而增大, 而对于碘甲烷此间距几乎不随电荷乘积变化; (5) CH_m⁺(m=0, 1, 2)的主要生成通道可能与碘甲烷不同, 不是来自CH₃⁺的顺序脱氢, 而是来自脱氢母体离子的直接解离.     

Simultaneous determination of bromide and iodide ions by capillary isotachophoresis using quaternary ammonium salts

Bromide and iodide ions were determined simultaneously by capillary isotachophoresis using an aqueous electrolyte system; the separation principle was based on the ion-pairing equilibria between tetradecyldimethylbenzylammonium ion and these anions in the leading electrolyte. The interaction between iodide ion and tetradecyldimethylbenzylammonium ion was stronger than that for bromide ion. Thus complete separation of bromide and iodide ions could be obtained by using a leading electrolyte containing 1.5 mM tetradecyldimethylbenzylammonium ion. The pH of the leading electrolyte was adjusted to 5.0. The relative standard deviations of the zone length for bromide and iodide ions were 1.1 and 1.2%, respectively, when mixture of 3.0 mM of these ions was analysed. A 150-μl volume could be injected for the simultaneous determination of low concentrations of bromide and iodide ions.     

Crystal structures of hydrates of simple inorganic salts. III. Water‐rich aluminium halide hydrates: AlCl3·15H2O,AlBr3·15H2O,AlI3·15H2O,AlI3·17H2O and AlBr3·9H2O

Water‐rich aluminium halide hydrate structures are not known in the literature. The highest known water content per Al atom is nine for the perchlorate and fluoride. The nonahydrate of aluminium bromide, stable pentadecahydrates of aluminium chloride, bromide and iodide, and a metastable heptadecahydrate of the iodide have now been crystallized from low‐temperature solutions. The structures of these hydrates were determined and are discussed in terms of the development of cation hydration spheres. The pentadecahydrate of the chloride and bromide are isostructural. In AlI₃·15H₂O, half of the Al³⁺ cations are surrounded by two complete hydration spheres, with six H₂O in the primary and 12 in the secondary. For the heptadecahydrate of aluminium iodide, this hydration was found for every Al³⁺.     

Extraction of gold, palladium and platinum from chloride, bromide and iodide solution with di-n-octyl sulphide (DOS) in cyclohexane

The extraction of gold, palladium and platinum from hydrochloric acid, hydrobromic acid and iodide media by solutions of di-n-octyl sulphide in cyclohexane was examined. From distribution data it was concluded that the monosolvates AuX(3).DOS and disolvates PdX(2).2DOS are extracted. Extraction of platinum was efficient only from iodide solutions; a disolvate PtI(4).2DOS was formed. The possibility of separation of gold and palladium from platinum by extraction from bromide or chloride solutions and simultaneous extraction of palladium and platinum from an iodide medium was demonstrated.     

Kinetic study of the iodate—iodide and chlorate—iodide reactions in acidic solutions,and a method for the microdetermination of bromide

The iodate—iodide and chlorate—iodide reactions were studied spectrophotometrically in acidic solutions by stopped-flow techniques. Intermediate products(I⁺)were followed; reaction rate constants and activation energies of the reactions were determined. A method of determining bromide was developed on the basis of its accelerating effect on the iodate—iodide reaction ; microamounts of bromide in the range 16–320 μg (10^-4–2 × 10^-3M) were determined with relative errors and relative standard deviation of about 2%.bl]     

Effect of bromide on the interfacial structure of aqueous tetrabutylammonium iodide: Photoelectron spectroscopy and molecular dynamics simulations

Solvation of surface-active tetrabutylammonium iodide (TBAI) in liquid water and in sodium bromide aqueous solution was investigated by VUV photoelectron spectroscopy and by molecular dynamics simulations. The observed signal intensity changes in the photoemission spectra are consistent with the varying propensities of the different ions for the solution interface. While the cations are surface-bound due to hydrophobic interactions, the anions are driven to the vacuum/solution interface by their large polarizability and size. Iodide is more polarizable, and hence more surface-active than bromide, which explains the relatively small decrease of the iodide photoemission signal when TBAI is dissolved in bromide solution.     

Enhancement of electron-capture detection of methyl bromide in air by iodination.

An instrumentally simple and cost-effective method for the direct analysis of methyl bromide in ambient air is described. The method is based on the separation of sample components by gas chromatography, the conversion of methyl bromide to methyl iodide by reaction with an inorganic iodide salt, and the detection of the methyl iodide thereby produced by an electron-capture detector. Of the 20 different inorganic salts investigated here for conversion of methyl bromide to methyl iodide, zinc iodide was found to provide the greatest conversion efficiency. In addition, zinc iodide was found to provide high conversion efficiency at a modest reaction temperature, thereby minimizing both the thermal decomposition of compounds within the reaction volume and the level of column bleed introduced to the detector. The reactions of several other brominated and chlorinated organic compounds with zinc iodide have also been characterized. The successful application of this instrument to the quantitative determination of methyl bromide in a local background air sample is then demonstrated.     

Regio- and diastereocontrol in carbonyl allylation by 1-halobut-2-enes with Tin(II) halides

Regio- and diastereoselective carbonyl allylations of 1-halobut-2-enes with tin(II) halides are described. Tin(II) bromide in a dichloromethane-water biphasic system is an effective reagent for unusual alpha-regioselective carbonyl allylation of 1-bromobut-2-ene to produce 1-substituted pent-3-en-1-ols. The addition of tetrabutylammonium bromide (TBABr) to the biphasic system produces 1-substituted 2-methylbut-3-en-1-ols via usual gamma-addition which is opposite to the alpha-addition without TBABr. The gamma-addition to aromatic aldehydes exhibits anti-diastereoselectivity, while that to aliphatic aldehydes is not diastereoselective. The allylation of benzaldehyde by 1-chlorobut-2-ene in 1,3-dimethylimidazolidin-2-one (DMI) does not occur with tin(II) chloride or bromide but does proceed with tin(II) iodide and exhibits gamma-syn selectivity which is unusual for a Barbier-type carbonyl allylation. In the carbonyl allylation by 1-chlorobut-2-ene with any tin(II) halide, the addition of tetrabutylammonium iodide (TBAI) accelerates the reaction and enhances gamma-syn selectivity. The use of tin(II) iodide and TBAI produces 2-methyl-1-phenylbut-3-en-1-ol with high yield and high syn-diastereoselectivity. The syn-diastereoselective carbonyl allylation of 1-chlorobut-2-ene using tin(II) iodide, a catalytic amount of TBAI, and NaI in DMI-H(2)O is applied to various aldehydes.     

Fluorescent charge-assisted halogen-bonding macrocyclic halo-imidazolium receptors for anion recognition and sensing in aqueous media

The synthesis and anion binding properties of a new family of fluorescent halogen bonding (XB) macrocyclic halo-imidazolium receptors are described. The receptors contain chloro-, bromo-, and iodo-imidazolium motifs incorporated into a cyclic structure using naphthalene spacer groups. The large size of the iodine atom substituents resulted in the isolation of anti and syn conformers of the iodo-imidazoliophane, whereas the chloro- and bromo-imidazoliophane analogues exhibit solution dynamic conformational behavior. The syn iodo-imidazoliophane isomer forms novel dimeric isostructural XB complexes of 2:2 stoichiometry with bromide and iodide anions in the solid state. Solution phase DOSY NMR experiments indicate iodide recognition takes place via cooperative convergent XB-iodide 1:1 stoichiometric binding in aqueous solvent mixtures. (1)H NMR and fluorescence spectroscopic titration experiments with a variety of anions in the competitive CD(3)OD/D(2)O (9:1) aqueous solvent mixture demonstrated the bromo- and syn iodo-imidazoliophane XB receptors to bind selectively iodide and bromide respectively, and sense these halide anions exclusively via a fluorescence response. The protic-, chloro-, and anti iodo-imidazoliophane receptors proved to be ineffectual anion complexants in this aqueous methanolic solvent mixture. Computational DFT and molecular dynamics simulations corroborate the experimental observations that bromo- and syn iodo-imidazoliophane XB receptors form stable cooperative convergent XB associations with bromide and iodide.     

Catalytic titration of iodide, bromide and thiocyanate by use of the silver catalysed phloxin-persulphate reaction

A method for the catalytic titrimetric determination of iodide, bromide and thiocyanate is described, based on the inhibitory effect of these anions on the silver-catalysed oxidation of phloxin by persulphate in the presence of 2,2'-bipyridyl. The end-point is determined photometrically by measuring the absorbance at 537 nm. Amounts of iodide, bromide and thiocyanate in the 0.01-7.94, 0.11-4.73 and 0.12-3.59mg ranges, respectively, are titrated with a relative error of about 1%.     

双吡唑啉酮(BPMPHD)和半菁与镧、镝的两亲性配合物的合成、表征与Langmuir-Blodgett膜的二阶非线性光学性质

合成了[1,6-双(1'-苯基-3'-甲基-5'-吡唑啉酮-4']-己二酮[1,6]合稀土(La,Dy)酸(E)-N-十六烷基-4-(2,4'-二甲氨基苯基)乙烯基吡啶两个新的稀土配合物。用元素分析、紫外可见光谱、红外光谱、差热热重谱、X射线粉末衍射、核磁共振谱和摩尔电导测量对配合物进行了表征。空气-水(18℃,pH5.4)界面上的表面压-面积(π-A)等温线研究表明,两配合物的Langmuir成膜性明显优于半菁溴化物和碘化物。二次谐波发生(SHG)实验测得镝配合物的二阶分子超极化率β为4.8×10^-^4^8C m^3 V^-^2,较半菁碘化物大约3.4倍。     

Thermal analytical and infrared spectroscopic investigations on polymorphic organic compounds—IV

Twenty-four polymorphic compounds which show between two and four modifications are cited. The compounds described in detail are tetrabutylammonium iodide, tetraheptylammonium bromide, tetraoctylammonium bromide, 3-(3,4,5-trimethoxyphenyl)-2-propenoic acid andl-tyrosine ethyl ester hydrochloride. For the remaining nineteen compounds, only the number of modifications found, and their melting points where possible, are given.     

Leaving group effects in gas-phase substitutions and eliminations

Using a methodology recently developed for studying the product distributions of gas-phase S(N)2 and E2 reactions, the effect of the leaving group on the reaction rate and branching ratio was investigated. Using a dianion as the nucleophile, reactions with a series of alkyl bromides, iodides, and trifluoroacetates were examined. The alkyl groups in the study are ethyl, n-propyl, n-butyl, isobutyl, isopropyl, sec-butyl, and tert-butyl. The data indicate that leaving group abilities are directly related to the exothermicities of the reaction processes in both the gas phase and the condensed phase. Gas-phase data give a reactivity order of iodide > trifluoroacetate > bromide for S(N)2 and E2 reactions. Previous condensed phase data indicate a reactivity order of iodide > bromide > trifluoroacetate for substitution reactions; however, the basicities of bromide and trifluoroacetate are reversed in the condensed phase so this reactivity pattern does reflect the relative reaction exothermicities. Aside from this variation, the gas-phase data parallel condensed phase data indicating that the substituent effects are rooted in the nature of the alkyl substrate rather than in differences in solvation. The experimental data are supported by calculations at the MP2/6-311+G(d,p)//MP2/6-31+(d) level.     

A simple, efficient alternative for highly stereoselective iodoacetoxylation of protected glycals

Protected glycals are converted in high yields and selectivities in less than 2 h at low temperatures to 2-deoxy-2-iodoglycosyl acetates using the simple, inexpensive reagent mixture of ammonium iodide, hydrogen peroxide and acetic anhydride/acetic acid in acetonitrile. The corresponding 2-deoxy-2-bromoglycosyl acetates are obtained using ammonium bromide instead of the iodide, although longer reaction times are required and selectivities are inferior.     

Ion-isotopic exchange reaction kinetics using organic base anion exchange resins Indion-102 and Indion GS-400

The present study deals with the kinetic study of iodide and bromide ion-isotopic exchange reactions in organic based anion exchange resins Indion-102 (nuclear grade) and Indion GS-400 (non-nuclear grade) using radiotracer isotopes. The resins in iodide and bromide form were equilibrated respectively with iodide and bromide ion solutions which were previously spiked with ¹³¹I and ⁸²Br radiotracer isotopes. For both bromide and iodide ion-isotopic exchange reactions, it was observed that the values of specific reaction rate increase with increase in ion concentration from 0.001 to 0.004 M at a constant temperature of 40.0°C. However, at constant ion concentration of 0.003 M, the specific reaction rate was observed to decrease with rise in temperature from 30.0 to 45.0°C. Also it was observed that for iodide ion-isotopic exchange reaction by using Indion-102 resin, the values of specific reaction rate, amount of iodide ion exchanged, initial rate of iodide ion exchange and logK _d were 0.258 min^?1, 0.492 mmol, 0.127 mmol/min and 19.2, respectively, which were higher than 0.208 min^?1, 0.416 mmol, 0.087 mmol/min and 17.6, respectively, obtained by using Indion GS-400 resin under identical experimental conditions of 40.0°C, 1.000 g of ion exchange resin and 0.003M labeled iodide ion solution. The same trend was observed for the two resins during bromide ion-isotopic exchange reaction. The overall results indicate that, under identical experimental conditions, Indion-102 resin shows higher performance than Indion GS-400 resin.     

Crystal structures of hydrates of simple inorganic salts. II. Water‐rich calcium bromide and iodide hydrates: CaBr2·9H2O,CaI2·8H2O,CaI2·7H2O and CaI2·6.5H2O

Single crystals of calcium bromide enneahydrate, CaBr₂·9H₂O, calcium iodide octahydrate, CaI₂·8H₂O, calcium iodide heptahydrate, CaI₂·7H₂O, and calcium iodide 6.5‐hydrate, CaI₂·6.5H₂O, were grown from their aqueous solutions at and below room temperature according to the solid–liquid phase diagram. The crystal structure of CaI₂·6.5H₂O was redetermined. All four structures are built up from distorted Ca(H₂O)₈ antiprisms. The antiprisms of the iodide hydrate structures are connected either via trigonal‐plane‐sharing or edge‐sharing, forming dimeric units. The antiprisms in calcium bromide enneahydrate are monomeric.     

Determination of nitrite and mixtures of bromide and iodide with o-iodosobenzoate

Nitrite diazotizes sulphanilamide, which then does not undergo 3,5-dibromination. Nitrite can therefore be determined by reaction with excess of sulphanilamide, the surplus of which is then titrated with o-iodosobenzoate or chloramine-T in the presence of potassium bromide, with Methyl Red as indicator. Mixtures of iodide and bromide can be analysed by oxidation of the iodide with excess of o-iodosobenzoate at pH 4-6, followed by extraction of the iodine (which is then titrated with thiosulphate) and then oxidation of the bromide in dilute sulphuric acid medium in the presence of sulphanilamide as bromine scavenger, the residual oxidant being evaluated iodometrically.