- EIN EINFACHES VERFAHREN ZUR SYNTHESE VON I UND EMe2 (E = Se, Te)
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Treatment of MeELi (E = Se, Te) with excess methyl iodide gives EMe3+ cations which are dealkylated by phosphanes PR3 (R = n-C4H9, C6H5) to give the dimethyl chalcogenides ER2 in good yields.
- Kuhn, N.,Faupel, P.,Zauder, E.
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- UV vapor generation for determination of selenium by heated quartz tube atomic absorption spectrometry
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A new vapor generation technique utilizing UV irradiation coupled with atomic absorption for the determination of selenium in aqueous solutions is described. In the presence of low molecular weight organic acid solutions, inorganic selenium(IV) is converted by UV irradiation to volatile selenium species, which are then rapidly transported to a heated quartz tube atomizer for detection by atomic absorption spectrometry. Optimum conditions for photochemical vapor generation and interferences from concomitant elements were investigated. Identification of the volatile products using cryotrapping GC/MS analysis revealed that inorganic selenium(IV) is converted to volatile selenium hydride, selenium carbonyl, dimethyl selenide, and diethyl selenide in the presence of formic, acetic, propionic, and malonic acids, respectively. In acetic acid solution, the efficiency of generation was estimated to be 50 ± 10%. No interference from Ni2+ and Co2+ at concentrations of 500 and 100 mg L-1, respectively, was evident. A detection limit of 2.5 μg L-1 and a relative sensitivity of 1.2 pg L-1 (1% absorption) with a precision of 1.2% (RSD, n = 11) at 50 pg L-1 were obtained.
- Guo, Xuming,Sturgeon, Ralph E.,Mester, Zoltan,Gardner, Graeme J.
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- Process for the preparation of group IVA and group VIA compounds
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Methods of preparing Group IVA and Group VIA organometallic compounds, particularly Group IVA organometallic compounds, are provided. Such manufacturing methods employ an amine and/or phosphine catalyst in a transalkylation step and may be performed in a batch, semi-continuous or continuous manner.
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- NEW ROUTE TO ORGANIC SELENIDES AND TELLURIDES
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A new simple and convenient synthetic route to organic chalcogenides R2Y (R = alkyl, allyl, benzyl; Y = Se, Te) is developed, which involves generation of Se2- and Te2- anions from Se and Te in the system KOH-hydrazine hydrate, where the latter plays the role of both the medium and reducing agent.Subsequent alkylation of the anions with the corresponding alkyl halides furnishes the target chalcogenides in almost 95percent yield.Alkyl chlorides react faster than alkyl bromides and alkyl iodides.
- Korchevin, N. A.,Podkuiko, P. A.,Stankevich, V. K.,Deryagina, E. N.,Trofimov, B. A.
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- Synthesis of Selenolates from Stannyl and Silyl Alkylselenides
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Stannyl and silyl alkylselenides have been efficiently transformed to the corresponding alkylselenolates on reaction with butyllithiums.Other conditions proved to be limited.
- Krief, Alain,Badaoui, Elie,Dumont, Willy
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p. 8521 - 8522
(2007/10/02)
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- Gas Phase Reactions, 40. Selenoformaldehyde: Highly Correlated Wave Function and Photoelectron Spectroscopic Evidence
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A systematic search for the unknown molecule selenoformaldehyde, H2C=Se, starts with the precalculation of its ionization pattern from ab-initio-PNO-CI and CEPA wave functions.The selenium precursors H3CSeSeCH3, H3CSeCN, H3CSeCl, and (H2CSe)3 are pyrolyzed in a flow system under PE spectroscopic real-time analysis: Applying "computerized spectra stripping" to the PE spectra of the pyrolysis mixtures, an ionization pattern can be extracted which correlates satisfactorily with the quantum chemical prediction for H2C=Se.To further support the assignment, selenoacetaldehyde, CH3CH=Se, and selenocarbonyl difluoride, F2C=Se, are prepared by thermal monomerization of 3 and (F2CSe)2, respectively.
- Bock, Hans,Aygen, Sitki,Rosmus, Pavel,Solouki, Bahman,Weissflog, Eckhard
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p. 187 - 202
(2007/10/02)
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- SYNTHESIS, PROPERTIES, AND MULTINUCLEAR (1H, 13C, 77Se) NUCLEAR MAGNETIC RESONANCE STUDIES OF SELENOETHERS CONTAINING TWO OR MORE SELENIUM ATOMS
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A convenient synthesis of MeSeLi from MeLi and Se8 in tetrahydrofuran (THF) has been used to prepare the bis-selenoethers MeSenSeMe (n = 1,2,3,6, or 12) and cis-MeSeCH=CHSeMe.PhSenSePh (n = 1-3) and cis-PhSeCH=CHSePh have been prepared from PhSe-, itself produced from Ph2Se2 and LiALH4-THF or sodium hydroxymethanesulphinate.The bis-selenoethers o-C6H4(SeR)2 (R = Me or Ph) were obtained from R2Se2 and benzyne.The syntheses of (RSeCH2)3CMe (R = Me or Ph), (MeSeCH2)4C, and (MeSeCH2CH2CH2)2Se are also described.The 1H, 13C, and 77Se n.m.r. spectra of these selenoethers have been recorded, and the chemical shifts and coupling constants (nJSe-H, nJSe-C) are discussed in terms of structures.Mass spectra of the selenoethers have been recorded and the principle fragmentation modes identified.
- Gulliver, David J.,Hope, Eric G.,Levason, William,Murray,Stephen G.,Potter, David M.,Marshall, Gregory L.
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p. 429 - 434
(2007/10/02)
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- ALKYL VINYL SELENIDES FROM ACETYLENE, ELEMENTAL SELENIUM, AND ALKYL HALIDES
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Elemental selenium reacts with acetylene and alkyl halides when heated (105-115 deg C) in an aqueous alkaline medium and gives alkyl vinyl selenides (with yields of up to 44percent) in addition to divinyl and dialkyl selenides.
- Gusarova, N. K.,Potapov, V. A.,Amosova, S. V.,Trofimov, B. A.
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p. 2168 - 2171
(2007/10/02)
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- NOVEL REDUCTION OF CHLORINE ADDUCTS OF ARYL AND ALKYL SELENIDES WITH DIMETHYL SULFOXIDE
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The adducts of chlorine with diaryl selenides such as selenanthrene, diphenyl selenide, and selenoxanthone have been found to be reduced to the corresponding selenides in dimethyl sulfoxide forming chloromethyl methyl sulfoxide and hydrogen chloride.Similarly, dimethyl selenide dichloride was reduced to dimethyl selenide in the presence of a base.
- Nakanishi, Waro,Sakaue, Akira,Ikeda, Yoshitsugu,Iwamura, Hiizu
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- Gas Phase Reactions, 23. Thermal decomposition of Open-Chain Dialkyl Sulfides, Disulfides and Diselenides
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The thermal decomposition of the dialkyl chalcogenide derivatives RSR, RSSR and RSeSeR (R = CH3, CH2CH3, CH2CH2CH3, CH(CH3)2, C(CH3)3) in a heated flow tube is analyzed and optimized using PE spectroscopy.Whereas high-temperature pyrolysis >1000 K yields mixtures of thermodynamically favored final products like H2, CH4, CS2, and HCCH, the lowest thermal reaction channel produces homogeneously olefin, H2S, and sulfur or olefin, alkaneselenol, H2Se, and selenium, respectively.The decomposition temperatures increase from RSeSeR via RSSR towards RSR and also with decreasing size of the alkyl groups.Based on the experimental data the possible course of the thermal decomposition is discussed.
- Hirabayashi, Takakuni,Mohmand, Shamsher,Bock, Hans
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p. 483 - 491
(2007/10/02)
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