Reactivity of main grouptransmittion metal bonds : III. Reactions of halogens with Ph3SiMn(CO)5 and Ph3SnMn(CO)5

The products of the reaction of Ph₃MMn(CO)₅ (M = Si or Sn) with chlorine, bromine and iodine in tetrachloromethane, have been determined.Ph₃SiMn(CO)₅ does not react with iodine, and the SiMn bond is cleaved by chlorine and by bromine.Ph₃SnMn(CO)₅ reacts in a much more complex manner, PhSn bond cleavage occurring with all three halogens to give mono-, di-, and, with the exception of iodine, tri-halogenated derivatives. Bromine, in high concentration, and iodine also cleave the SnMn bond.     

Determination of chlorine, bromine and iodine in rock samples by radiochemical neutron activation analysis

Chlorine, bromine and iodine (hereafter, halogens) were detemined for rock samples by radiochemical neutron activation analysis. The powdered samples and reference standards prepared from chemical reagents were simultaneously irradiated for 10 to 30 minutes with or without a cadmium filter in a TRIGA-II reactor at the Institute for Atomic Energy, Rikkyo University. The samples were subjected to radiochemical procedures of halogens immediately after the irradiation. Iodine was firstly precipitated as PdI₂, and chlorine and bromine were successively precipitated as Ag-halides at the same time. In this study, geological standard rocks, sedimentary rocks and meteorites were analyzed for trace halogens. In some Antarctic meteorites, iodine contents were observed to be anomalously high. Chlorine contents also are somewhat high. The overabundance of iodine and chlorine must be caused by terrestrial contamination on the Antarctica.     

Coulometric determination of sulfur-containing amino acids using halogens as oxidizing titrants

It is found that cysteine and methionine quantitatively react with electrogenerated halogens under the conditions of galvanostatic coulometry. Cysteine reacts with all titrants, and methionine reacts only with chlorine and bromine. The stoichiometric coefficients of reactions between cysteine and halogens are 1:3, 1:3, and 1:1 for chlorine, bromine, and iodine, respectively. These coefficients for methionine reactions with chlorine and bromine are 1:2 and 1:1, respectively. It is shown that cysteine can be selectively determined in its mixtures with methionine by coulometric titration with electrogenerated iodine. It is found that twofold amounts of methionine do not interfere with the determination of cysteine. A procedure is developed for the direct coulometric determination of methionine in tablets with a relative standard deviation of 3–5%.     

Comparative study of activation analyses for the determination of trace halogens in geological and cosmochemical samples.

Halogens (fluorine, chlorine, bromine and iodine) were determined by activation analyses (neutron activation analysis (NAA), photon activation analysis (PAA) and prompt gamma-ray analysis (PGA)) for geological and cosmochemical solid samples. We studied how each analytical method was for the determination of trace amounts of halogens in rock samples. Radiochemical NAA (RNAA) showed the highest analytical reliability for three halogens (chlorine, bromine and iodine), whereas a set of four halogens (fluorine, chlorine, bromine and iodine) could be determined in principle by radiochemical PAA (RPAA) from a single specimen. Although it is a non-destructive method, PGA showed an analytical sensitivity for chlorine comparable to those of RNAA and RPAA.     

The simultaneous microdetermination of chlorine,bromine, and iodine in organic compounds by the oxygen flask method

Summary A method is described which allows the simultaneous microdetermination of chlorine, bromine and iodine following organic decomposition by the oxygen flask procedure ofSchöniger. Sodium borohydride is employed as a reducing agent in the absorbing solution. The sum of halogens is titrimetrically determined in an aliquot of the absorbing solution by means of 0.01N mercuric perchlorate solution. The bromine and iodine are determined in different aliquots after oxidation to halate. Furthermore individual halogens can be determined by this method. The proposed method is simple, rapid, and highly reproducible.

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Zusammenfassung Ein Verfahren zur gleichzeitigen Bestimmung von Chlor, Brom und Jod nach Zerstörung der organischen Substanz im Verbrennungskolben wurde beschrieben. Natriumborhydrid dient als Reduktionsmittel in der Absorptionslösung. Die Summe der Halogene wird mit 0,01-n Quecksilberperchlorat in einem Teil dieser Lösung titriert. Brom und Jod werden in weiteren Teilen nach ihrer Oxydation zu Halogenat bestimmt. Außerdem kann jedes Halogen für sich nach diesem gut reproduzierbaren Verfahren bestimmt werden.

     

Crystal Growth of Chromium Silicides by chemical vapour transport with halogens. 2. Growth of the Cr-rich silicide crystals

Chromium silicides with Cr:Si ≥ 1, CrSi, Cr₅Si₃, and Cr₃Si, were grown by C.V.T. with halogens as transport medium. A sequential transport behaviour is typical in the multiphase Cr? Si system. Using chlorine and bromine as transport agent a transport from hot to cold has been observed. CrSi can be obtained only with Br₂ or I₂ due to the subsequent transport, which causes CrSi₂ to be grown with Cl₂ even if the source material is a CrSi/Cr₅Si₃ mixture. Using iodine as transport agent a transport from cold to hot was found in each case. The dissolution and the deposition processes of the solids are discussed taking into account the composition of the gas phase. There is a good agreement between the thermodynamic analysis and the results of the experiments.     

The effect of the counterion composition on the chain restriction in the cationic polymerization of isobutylene

The effects of the nature of halogens in the initiatingtert-butyl halide-aluminum-containing Lewis acid system on the number average molecular weightM _n and the structure of end groups of polyisobutylene macromolecules obtained in the cationic polymerization of isobutylene in hexane at -78 °C were studied. An increase inM _n is observed in the transition from chlorine to bromine and iodine, accompanied by a decrease in the fraction of end C=C groups and an increase in the relative content of C-Hal groups (Hal = Cl, Br, and I). When atoms of different halogens are present in the counterion, more bulky atoms preferentially participate in the formation of the end groups. The results are interpreted within the framework of the principle of hard and soft acids and bases.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1184–1187, May, 1996.     

Catalytic and chemoselective deprotection of S,S- and S,O-acetals and ketals in the presence of their O,O-analogs with electrophilic halogens under neutral conditions

A novel and catalytic method is described for the selective deprotection of S,S- and S,O-acetals and ketals in the presence of their O,O-analogs to their corresponding carbonyl compounds based on the use of N-bromosuccinimide (NBS), N-chlorosuccinimide (NCS), 2,4,4,6-tetrabromo-2,5-cyclohexadiene-1-one (TABCO), trichlorocyanuric acid (TCCA) or molecular bromine as sources of electrophilic halogens in the presence of DMSO as the source of oxygen in CHCl₃.     

Bromophosgenite: Synthesis and structure solution

Hydrothermally synthesized lead carbonate Pb₂Br₂(CO₃), a bromine analogue of phosgenite mineral Pb₂Cl₂(CO₃), space group P4/mbm, is structurally studied. A comparison of the bromine and chlorine phosgenite analogues is carried out. It is shown that the structure type of the formula analogues changes when fluorine or oxygen substitutes for their large halogens.     

Halogen fluorosulfate reactions with fluorocarbons

The scope of the reaction of simple fluorocarbon halides with chlorine fluorosulfate and mixtures of chlorine and bromine fluorosulfate to produce R_fOSO₂F compounds has been investigated. It is shown that in many cases even primary chlorine in -CF₂Cl groups can be replaced by -OSO₂F, Primary bromine or iodine in -CF₂X are more readily replaced. The mechanism of this replacement reaction has been established by the isolation of the metastable iodine III intermediate R_fI(OSO₂F)₂. Neither secondary chlorine nor bromine in -CFX- groups is affected. With the secondary iodide, i-C₃F₇I, the salt [(i-C₃F₇)₂I]⁺ [I(OSO₂F)₄]^? is formed. Furthermore, it has been found that ClOSO₂F is capable of converting fluorocarbon acids or their derivatives into fluorocarbon halides. A combination of these two ClOSO₂F reactions with the known conversion of R_fCF₂OSO₂F to the corresponding fluorocarbon acid offers a novel, high yield chain shortening reaction for the otherwise unreactive fluorocarbon halides according to:

     

Comparative Study of Halogen‐ and Hydrogen‐Bond Interactions between Benzene Derivatives and Dimethyl Sulfoxide

The halogen bond, similar to the hydrogen bond, is an important noncovalent interaction and plays important roles in diverse chemistry‐related fields. Herein, bromine‐ and iodine‐based halogen‐bonding interactions between two benzene derivatives (C₆F₅Br and C₆F₅I) and dimethyl sulfoxide (DMSO) are investigated by using IR and NMR spectroscopy and ab initio calculations. The results are compared with those of interactions between C₆F₅Cl/C₆F₅H and DMSO. First, the interaction energy of the hydrogen bond is stronger than those of bromine‐ and chlorine‐based halogen bonds, but weaker than iodine‐based halogen bond. Second, attractive energies depend on 1/rⁿ, in which n is between three and four for both hydrogen and halogen bonds, whereas all repulsive energies are found to depend on 1/r^8.5. Third, the directionality of halogen bonds is greater than that of the hydrogen bond. The bromine‐ and iodine‐based halogen bonds are strict in this regard and the chlorine‐based halogen bond only slightly deviates from 180°. The directional order is iodine‐based halogen bond>bromine‐based halogen bond>chlorine‐based halogen bond>hydrogen bond. Fourth, upon the formation of hydrogen and halogen bonds, charge transfers from DMSO to the hydrogen‐ and halogen‐bond donors. The CH₃ group contributes positively to stabilization of the complexes.     

Alkenyl derivatives of 5-nitro-2-pyridone: Synthesis and halocyclization

Alkylation of 5-nitro-2-pyridone by alkenyl halides in acetone in the presence of K₂СО₃ proceeds with generation of a mixture of N- and О-derivatives with N-isomer prevailing. 1-Allyl- and 1-methylallyl-5-nitro-2-pyridone react with halogens with the formation of 2-halomethyl-6-nitro-2,3-dihydrooxazolo[3,2-a]-pyridinium halides. 1-Prenyl-5-nitro-2-pyridone reacts with bromine with the formation of 3-bromine-2,2-dimethyl-7-nitro-3,4-dihydro-2Н-pyrido[2,1-b][1,3]oxazinium bromide, and with iodine giving 2,2-dimethyl-7-nitro-3,4-dihydro-2Н-pyrido[2,1-b][1,3]oxazinium triiodide.     

Titrimetric methods for the microdetermination of halogens in organic compounds by the rapid combustion procedure: The determination of individual halogens

A critical study has been carried out of titrimetric methods suitable for the microdetermination of each of the halogens, chlorine, bromine and iodine, in their possible organic combinations with the elements, oxygen, nitrogen and sulphur, following organic decomposition by the rapid empty tube combustion procedure.     

Reaction of polyfluoroaromatic compounds with electrophilic agents in the presence of tris(dialkylamino)phosphines

A method was developed for the replacement of chlorine, bromine, and iodine in halopolyfluoroaromatic compounds by hydrogen under the action of P(NEt₂)₃ and a proton donor.     

Synthesis and Properties of Copper,Mercury, and Silver (2-Naphthyl)acetylenides

(Z)-2-Naphthylacetylene was synthesized by the reaction of (Z)-3-(2-naphthyl)-3-chloropropenal (prepared from 2-acetylnaphthalene) with aqueous NaOH in dioxane. The reactions of 2-naphthylacetylene with CuCl, [Ag(NH₃)₂]NO₃, and K₂[HgI₄] gave copper, silver, and mercury 2-naphthylacetylenides, respectively. Silver naphthylacetylenide reacts with iodine to give the iodoethynyl derivative, which readily takes up bromine across the triple bond.     

The Reactivity of CF3C6F4OC6F4Li towards Halogens and Cyanogen Halides

The reaction of 4‐(4′‐trifluoromethyl‐tetrafluorophenoxy)‐tetrafluorophenyllithium (R_FLi, 1 ) with halogens, dicyanogen, cyanogen halides, and xenon difluoride was examined. The corresponding halogenated aromatics R_FCl ( 2 ), R_FBr ( 3 ) and R_FI ( 4 ) were formed upon reaction with chlorine, bromine, and iodine. Essentially the same products were isolated in the reaction of 1 with cyanogen chloride, bromide, and iodide, respectively. The nitrile R_FCN ( 5 ) was obtained from the reaction of 1 with dicyanogen only as a minor product. The reaction of 1 with XeF₂ resulted in the isolation of R_FCH(CH₃)CH₂CH₃ ( 6 ). All products were identified and characterized by analytical and spectroscopic methods. In addition the molecular structures of 2 , 3 , and 4 have been determined by X‐ray crystallography. The reaction enthalpies for the gas phase reactions of pentafluorophenyllithium, C₆F₅Li, as a model for 1 , with XCN (X = F, Cl, Br, I) were calculated.     

Simultaneous microdetermination of iodine and chlorine or iodine and bromine in organic compounds

Summary A micromethod for simultaneous determination of iodine and chlorine or iodine and bromine in organic compounds is described. After combustion in an oxygen-filled separatory funnel containing acidic sodium nitrite, iodine is produced, separated by carbon tetrachloride and oxidised with bromine water to iodate. After removal of carbon tetrachloride and excess bromine, the iodate is determined iodometrically. The aqueous combustion product is determined mercurimetrically for either chlorine or bromine. The average recoveries are 98.7%, 100.7% and 100.6% with iodine, chlorine and bromine in mixtures of their organically bounded compounds respectively. Microdetermination of iodine in presence of other halogens using sodium nitrite as absorbing agent andLeipert's method is described.

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Zusammenfassung Eine Mikromethode zur gleichzeitigen Bestimmung von J und Cl oder J und Br in organischen Verbindungen wurde beschrieben. Nach der Verbrennung in einem sauerstoffgefüllten Scheidetrichter in Anwesenheit angesäuerter Natriumnitritlösung wird Jod freigesetzt, mit Tetrachlormethan extrahiert und mit Bromwasser zu Jodat oxydiert. Nach Entfernung des Tetrachlorkohlenstoffs und des Bromüberschusses wird das Jodat jodometrisch titriert. In der wäßrigen Lösung wird mercurimetrisch Chlor bzw. Brom bestimmt. Die durchschnittliche Ausbeute beträgt 98,7, 100,7% und 100,6% für Jod, Chlor bzw. Brom in Gemischen ihrer organischen Verbindungen. Die Mikrobestimmung des Jods in Gegenwart anderer Halogene nach Absorption in Nitritlösung nach der Methode vonLeipert wurde beschrieben.

     

The Quantitative Removal and Recovery of Chlorine and Bromine from Air Streams with 2,1,3-Benzoselenadiazole

Abstract

The affinity of 2,1,3-Benzeneselenadiazole (piaselenole) for dimeric chlorine and bromine has been investigated. A 1:1 adduct is formed between piaselenole and both molecular C1₂ and Br₂. At slow flow rates, piaselenole quantitatively removes halogens from contaminated air strcams. The adducts, upon reaction with water or gentle heating in an oil solution, liberates the halogen and regenerates the piaselenole.     

Synthesis of new T-shaped hypervalent complexes of tellurium showing Te–π-aryl interactions: X-ray characterization of [(mes)XTe(μ-X)Te(mes)(etu)] (X = Br,I) and [Ph(etu)Te(μ-I)Te(etu)Ph][PhTeI4] (mes = mesityl; etu = ethylenethiourea)

Dimesityl ditelluride, (mesTe)₂, reacts with bromine/iodine and ethylenethiourea in methanol to give [(mes)XTe(μ-X)Te(mes)(etu)] {X = Br (1), I (2)}. The salt [Ph(etu)Te(μ-I)Te(etu)Ph][PhTeI₄] (3) is obtained by reflux of a mixture of (PhTe)₂, iodine, ethylenethiourea and PhTeI₃ in methanol. The new complexes were prepared in good yields by a one-pot procedure and characterized by single crystal X-ray diffraction. In the complexes 1 and 2, the tellurium atoms perform Te–π-aryl interactions and attain T-shaped coordinations with a bridging halogen ligand. The [PhTeI₄]⁻ anions of complex 3 are associated in a quasi-dimeric configuration and the tellurium atoms achieve an octahedral coordination through secondary Te–I bonds.     

Ligandenaustauschreaktionen von Fluoratomen mit Chloratomen bei Phosphorverbindungen der Koordinationszahl 3 und 4

Ligand-exchange reactions of fluorine versus chlorine atoms in phosphorus compounds with coordination number 3 or 4 Fluorine versus chlorine ligand-exchange reactions were carried out on the following phosphorus-based central moieties: CH₃P <, CH₃P(O)<, CH₃P(S)< and CH₃P(Se)<. The measured equilibrium distributions were shown to favour the species which result from an accumulation of like substituents on the central moieties, whereas the equilibrium distribution of chlorine vs bromine on CH₃P(O) < was found to be almost random. These fluorine exchanging systems thus represent the unusual case of large positive deviation from random distribution. It is also noteworthy that the equilibrium distributions depend only very little on the nature of the atom which is bonded to phosphorus in the “isolated” position. System CH₃PF₂/CH₃PCl₂ could not be studied quantitatively owing to the competitive dismutation of CH₃PF₂; however, evidence is given for fast initial redistribution of the halogens on the methylphosphorus moiety and for the transient formation of CH₃PFCl.