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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 4 (1971), S. 472-474 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Oxydation des Hexachlortechnetat(IV)-Ions durch Wasserstoffsuperoxid, Chlor und Luftsauerstoff wurde chromatographisch untersucht. Wasserstoffsuperoxid oxydiert das TcCl 6 2− -Ion direkt zum Pertechnetat-Ion. Bei Oxydation durch Chlor bildet sich zunächst Technetium(V) als Zwischenprodukt, das dann zum Pertechnetat-Ion oxydiert wird. Es wurde keine Oxydation des vierwertigen Technetiums durch Luftsauerstoff bei Sonnenlicht beobachtet.
    Abstract: Résumé L'oxydation de l'ion hexachlorotechnétate(IV) par l'eau oxygenée, le chlore et l'oxygène de l'air a été étudiée au moyen de la chromatographie. Avec l'eau oxygénée, l'ion TcCl 6 2− est directement oxydé, avec formation d'ion pertechnétate. Si l'on emploie le chlore, on obtient d'abord le technétium(V) (produit intermédiaire) puis celui-ci est oxydé en ion pertechnétate. Aucune oxydation du technétium tétravalent par l'oxygène atmosphérique à la lumière solaire n'a été observée.
    Notes: Summary Oxidation of hexachlorotechnetate (IV) ion by hydrogen peroxide, chlorine, and atmospheric oxygen was chromatographically studied. Hydrogen peroxide oxidizes the TcCl 6 2− ion directly to pertechnetate ion. The oxidation by chlorine first produces technetium (V) as an intermediate which is then oxidized to the pertechnetate ion. No oxidation of the tetravalent technetium by atmospheric oxygen in presence of sunlight was observed.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 4 (1971), S. 337-340 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird über die Reduktion von Pertechnetat-Ionen durch verdünnte Salzsäure und durch Lösungen von Lithiumchlorid und Natriumchlorid in verdünnter Salzsäure berichtet. Die Anwesenheit von Lithiumchlorid beschleunigt die Reduktion, während Natriumchlorid die Reduktionsgeschwindigkeit durch Salzsäure verlangsamt. Bei Abwesenheit von Säure wird auch bei einer Lithiumchlorid-Konzentration von 12 M keine Reduktion des Pertechnetat-Ions beobachtet.
    Abstract: Résumé On décrit la réduction des ions pertechnétate par l'acide chlorhydrique dilué et par des solutions de chlorure de lithium et de sodium dans l'acide chlorhydrique dilué. La présence du chlorure de lithium accélère la réduction; par contre, la vitesse de réduction par l'acide chlorhydrique est ralentie par le chlorure de sodium. En l'absence de l'acide on n'observe aucune réduction de l'ion pertechnétate même avec une solution 12 M. en chlorure de lithium.
    Notes: Summary The reduction of pertechnetate ions by dilute hydrochloric acid and by solutions of lithium chloride and sodium chloride in dilute hydrochloric acid is reported. The presence of lithium chloride accelerates the reduction, but sodium chloride slows down the rate of reduction by hydrochloric acid. In the absence of the acid no reduction of the pertechnetate ion is obsrved by a lithium chloride solution as concentrated as 12 M.
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  • 3
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es hat sich gezeigt, daß die Reduktion von Pertechnetat-Ionen durch verdünnte Salzsäure durch Zusatz von Bromid — oder Jodi-Ionen zum Reaktionsgemisch beschleunigt wird. Bei Raumtemperatur ist Alterung über zwei Jahre erforderlich, bevor konzentrierte Salzsäure das fünfwertige Technetium, das im ersten Stadium durch sofortige Reduktion des Pertechnetat-Ions entsteht, zu chromatographisch reinem Technetium (IV) reduziert. Es erwies sich, daß die Reduktionsgeschweindigkeit der Pertechnetat-Ionen durch konzentrierte Salzsäure im Bereich 0,3–8 mg/ml unabhängig von der Konzentration an Ammonium-Pertechnetat ist.
    Abstract: Résumé On a montré que la réduction des ions pertechnétate par acide chlorhydrique diué est accélŕee par l'addition d'ions brome et iode au mélange réactionnel. A la température ambiante, if faut deux années de viellissement pour que l'acide chlorhydrique concentré réduisse le technétium pentavalen (produit dans la première étape par réduction instantanée de l'ion pertechnétate) en technétium (IV) de pureté chromatographique. On a trouvé que la viesse de réduction de l'ion pertechnétate par l'acide chlorhydrique concentré est indépendante de la concentration du pertechnétate d'ammonium dans le domaine compris entre 0,3 et 8 mg/ml.
    Notes: Summary The reduction of pertechnetate ion by dilute hydrochloric acid has been shown to be accelerated by the addition of bromide or iodide ions to the reaction mixture. At room temperature, concentrated hydrochloric acid requires an aging of two years to reduce pentavalent technetium, produced in the first stage byan instantaneous reduction of pertechnetate ion, to chromatographically pure technetium (IV). The rate of the reduction of pertechnetate ion by concentrated hydrochloric acid was found to be independent of the concentraton of ammonium pertechnetate in the range of 0.3–8 mg/ml.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 5 (1972), S. 310-318 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Nach einer kurzen Übersicht über anorganische wäßrige Papier-Chromatographie werden die Eigenschaften von wasserfreien dipolaren aprotonischen Lösungsmitteln allgemein und von Dimethylsulfoxid (DMSO) im besonderen diskutiert, die sie als Fließmittel für saubere anorganische Papier-Chromatographie geeigneter erscheinen lassen als die protonischen Lösungsmittel. Die quantitative schnelle Trennung von Ferrocyanid- und Ferricyanid-Anionen, die bisher mit jedem wäßrigen System oder protonischem Lösungsmittel als mobile Phase untrennbar waren, wurde mühelos auf Papier-Chromatogrammen durchgeführt, die mit wasserfreiem DMSO entwickelt wurden. Das Trennvermögen von DMSO zwischen den beiden eng verwandten Anionen wird durch die Betrachtung der semipolaren Eigenschaften der S−O-Bindung, der molekularen und elektronischen Struktur von DMSO und des Unterschiedes in Ionenladung und Ionenvolumen der beiden Anionen erklärt.
    Abstract: Résumé Après avoir passé en revue les problèmes de la chromatographie sur papier en présence d'eau des substances minérales, l'auteur discute des propriétés des solvants aprotiques dipolaires non-aqueux et en particulier du diméthyl sulfoxyde (DMSO); leurs propriétés les rendent supérieurs aux agents de développement protiques pour la chromatographie sur papier des substances minérales. Une séparation quantitative et rapide des ions ferrocyanure et ferricyanure non-séparables, jusqu'à présent, avec les systèmes contenant de l'eau ou un solvant protonisé comme phase mobile a été obtenue par chromatographie sur papier avec développement par du DMSO anhydre. La différence de comportement, en présence de DMSO, des deux anions de propriétés est expliquée par voisines la nature semipolaire de la liaison S−O, la structure moléculaire et électronique du DMSO, et la différence de charge et volume ionique des deux anions.
    Notes: Summary After a short review of inorganic aqueous paper chromatography, the properties of anhydrous dipolar aprotic solvents in general and of dimethyl sulphoxide (DMSO) in particular, which recommend them as preferable developing solvents to the protic ones for clean inorganic paper chromatography, are discussed. A quantitative and rapid separation of ferrocyanide and ferricyanide anions, inseparable so far with any aqueous system or protic solvent used as mobile phase, was easily carried out on paper chromatograms developed with anhydrous DMSO. The differentiative behaviour of DMSO between the two closely related anions is explained by a consideration of the semipolar nature of the S−O bond the molecular and electronic structure of DMSO, and the difference in ionic charges and ionic volumes of the two anions
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 6 (1973), S. 463-467 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Complex formation in acetone-water systems has been investigated by studying solvent migration rate and chromatographic behaviour of hexacyanoferrate (II) and (III). The formation of mono-, tetra-, and decahydrates of acetone has been observed, of which the tetrahydrate, also observable by other physical properties of the solvent mixture, is the most stable.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 6 (1973), S. 371-374 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of all alkali metal ions in phenol saturated with 2M hydrochloric acid has been examined by centrifugal and ascending chromatography. Separation with centrifugal development is about one hundred times more rapid than that obtained by the ascending technique. The shortest separation time achieved in these studies, six minutes, shows that centrifugal chromatography promises to be a useful rapid technique for the separation of short-lived fracium isotopes from a mixture of other alkali metals and for the routine analysis of alkali metals. The different degree of solvation of the cations by phenol, depending upon ionic size, is considered to be mainly responsible for the observed selective distribution of the alkali metal ions on the chromatogram.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 6 (1973), S. 84-88 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The potential of dimethyl sulphoxide (DMSO) as a mobile phase for chromatography on ready-for-use, thin-layers of silica gel, cellulose, and alumina has been examined with ferro- and ferricyanide anions, applied alone or as a mixture, as systems to be separated. The most satisfactory results, with very compact spots, are observed with silica gel thin-layers. The behaviour on cellulose layers is similar to that on paper, but the chromatographic spots are more compact in the former case, and therefore the separation there is much cleaner and more rapid. On alumina layers both the anions are highly adsorbed at the point of application, and ferrocyanide is rapidly oxidized to ferricyanide in the presence of DMSO. Alumina layers are therefore unsuitable for chromatography in the present system. The differentiative behaviour of DMSO towards the two closely similar anions is explained by considering the semipolar nature of the S−O bond, the molecular and electronic structure of DMSO, and the difference in ionic volume and ionic charge of the two anions.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 6 (1973), S. 155-159 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interaction between dimethyl sulphoxide (DMSO) and water, occurring when the two liquids are mixed together, has been studied: 1. by the measurement of the rate of migration of the different solvent mixtures, over the whole concentration range, on paper chromatograms, and 2. by observing the paper chromatographic behaviour of hexacyanoferrate II anions when these mixtures are used as mobile phases. The rate of migration gives a very pronounced maximum at the solvent concentration which corresponds to the composition DMSO·H2O. The chromatographic behaviour of the hexacyanoferrate II ion besides confirming this conclusion shows the existence of three distinct zones of differing solvent structure and solvating behaviour.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 8 (1975), S. 27-32 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Interaction in the methanol-water system has been studied (i) by the measurement of the mobile phase migration rate in mixed solvents of different composition and (ii) by the changes in chromatographic behaviour of hexacyanoferrate (III) and (II) anions produced by the solvent system. The formation of semi-, mono-, di-, and trihydrates of methanol has been observed. Paper chromatographic separation of hexacyanoferrate (III) and (II) anions has been achieved in the concentration range 85 to 65% (v/v) aqueous methanol, used as a mobile phase.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 2665-2674 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aqueous polymerization of methyl methacrylate (MMA) initiated by potassium persulfate (I)-thiomalic acid (TMA) redox couple has been studied at 30 ± 0.2°C under nitrogen atmosphere. The rate of polymerization is given by \documentclass{article}\pagestyle{empty}\begin{document}$$ R_p = K[{\rm MMA}]^{0.98} [{\rm K}_2 {\rm S}_2 {\rm O}_8]^x [{\rm TMA}]^{0.44} $$\end{document} up to 20.0 mmol/L TMA concentration, where x = 0.52 for the I concentration 0.6-10 mmol/L and x = 0.27 for higher I concentrations. The temperature had a marked effect on initial rate and maximum conversion. The overall energy of activation was found to be 11.79 kcal/mol (49.31 kJ/mol). Injection of more initiator (I) at intermediate stages enhanced both the initial rate and maximum conversion. Ag (I) and Fe (III) depressed initial rate as well as maximum conversion, while Cu (II) activated the polymerization. The effect of solvent was also studied.
    Additional Material: 10 Ill.
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