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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2396-2406 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Hexafluoroacetone with Nitriles of Main Groups V and VIHexafluoroacetone (HFA) reacts with nitriles of group V elements like CF3P(CN)2 (1), P(CN)3 (2), and Sb(CN)3 (3) via E — CN bond cleavage to yield compounds 4 - 6. The reactions are catalyzed by triethylamine and proceed under mild conditions. A completely different reactivity is observed for Se(CN)2, where triethylamine is incorporated into the resulting compound 7. As(NCS)3 adds two molecules of HFA per ligand across the C ≡ N triple bond forming the symmetric trithioarsenite (8). The crystal structures of 4, 7, and 8 are reported.
    Notes: Hexafluoraceton (HFA) reagiert mit Nitrilen der V. Hauptgruppe, wie CF3P(CN)2 (1), P(CN)3 (2) und Sb(CN)3 (3), unter Spaltung der E — CN-Bindungen zu den Verbindungen 4 - 6. Triethylamin katalysiert die unter milden Bedingungen ablaufenden Reaktionen. Ein vollständig anderer Reaktionstyp wird im Fall des Se(CN)2 beobachtet; hier wird ein Molekül Triethylamin in die entstehende Verbindung 7 eingebaut. As(NCS)3 addiert je zwei Moleküle HFA über die C ≡ N-Dreifachbindung zum symmetrischen Trithioarsenit (8). Von 4, 7 und 8 werden die Kristallstrukturen mitgeteilt.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2659-2670 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Hexafluoroacetone with Alkali CyanatesNaSCN and KOCN react with hexafluoroacetone (HFA) in a molar ratio of 1:2 in a one-step reaction to yield the hexafluoropropanimine derivatives (CF3)2C=NC(CF3)2OM (2a, b) (M=Na, K). (CF3)2C=N- is a possible intermediate. Hydrolysis of 2a in aqueous tetraphenylphosphonium chloride solution yields a crystalline hydrate of composition [(CF3)2C(OH)2·(CF3)2C(O)OH]- Ph4P+ (3). In the solid state dimeric dianions are observed, which are connected via four asymmetrical and two symmetrical O⃛H⃛O bonds. Starting with a 1:1 KSCN/HFA stoichiometry the polycyclic bisspiro compound 5 is formed in a complex reaction. In the reaction of potassium selenocyanate with HFA the C-Se bond is cleaved and the CF3-substituted oxazolidine 6 is formed. The X-ray structure analyses of 2a, 3, 5 and 6 are reported.
    Notes: NaSCN und KOCN reagieren mit Hexafluoraceton (HFA) im Molverhältnis 1:2 unter Abbau des Anions in einem Schritt zu den Hexafluorpropanimin-Derivaten (CF3)2C=NC(CF3)2OM (2a, b) (M=Na, K), wahrscheinlich über (CF3)2C=N- als Zwischenstufe. Die Hydrolyse von 2a in Gegenwart wäßriger Tetraphenylphosphoniumchlorid-Lösung ergibt ein kristallines Hydrat der Zusammensetzung[(CF3)2C(OH)2·(CF3)2C(O)OH]- Ph4P+ (3). Im Kristall liegen dimere Dianionen vor, die über vier asymmetrische und zwei symmetrische Wasserstoff-Brückenbindungen verknüpft sind. In einer unübersichtlichen Reaktion entsteht bei einem Reaktandenverhältnis KSCN/HFA von 1:1 die polycylische Bisspiroverbindung 5. Kaliumselenocyanat reagiert mit HFA unter C - Se-Bindungsspaltung und nachfolgender Bildung des CF3-substituierten Oxazolidins 6. Die Röntgenstrukturanalysen von 2a, 3, 5 und 6 werden mitgeteilt.
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  • 3
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A kinetic study of the initiation reaction of alkyne polymerization by a transition metal intramolecular coordinated carbene complex, was carried out. It showed that there is a slow disappearance of the initial carbene and simultaneously appearance of both active species and organic side-products. Their structures were determined by GC-MS. The apparent rate constants of both initiation and side-reactions were measured and the corresponding thermodynamic parameters established. According to the experimental results, a mechanism of the initiation reaction is proposed. In the first step a replacement of the intramolecular double bond of the initiator by the triple bond of a monomer molecule takes place and in the second step the insertion of the monomer. The resulting carbenic active species may lead either to organic products via cyclopropanation reaction or to a high-molecular-weight polymer.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1613-1625 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An apparatus for turbidimetric measurements of demixing temperatures under shear flow is presented, and the results of experiments with trans-decahydronaphthalene/polystyrene (TD/PS) solutions, investigating molecular weights ranging from 100 kg/mol to 1770 kg/mol, are compared with viscometric data. It is found that the sign and magnitude of shear effects depend on molecular weight (Mw), polymer concentration (c2), and shear rate (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}). For the first time, it was possible to study a solution which exhibits shear dissolution at low shear rates but shear demixing at high shear rates.
    Additional Material: 11 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 1321-1333 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Various poly(acetoxymethylstyrene)s were synthesized. Examination of the physicochemical properties of the polymers as a function of the type of substitution revealed the influence of the position of polar groups on the thermal (glass transition temperature) and electrical (dielectric constant and loss factor) characteristics of the polymers. Because of their good solubility and their electrical properties over a wide range of temperatures and frequencies the polymers proved to be interesting materials for dielectric films.
    Additional Material: 8 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1627-1634 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phase diagrams were calculated for flowing solutions of polystyrene in trans-decahydronaphthalene assuming that the energy (Es) stored in the sheared state has to be added to the Gibbs energy of mixing; Es is computed from viscometric data (flow curves). The resulting phase diagrams exhibit two maxima in most of the cases instead of only one for the stagnant solutions. A comparison with experimental data (Part 1) shows that the calculated demixing behaviour agrees well for moderate shear rates and concentrations of the polymer. Deviations in the semidilute region, particularly for higher \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} values, are a consequence of the fact that so far no reliable theoretical relation has been given for these conditions to calculate Es from viscometric data. In all cases, however, the present attempt describes the characteristics of the phase diagrams very well, namely the eulytic points and the inversion of shear dissolution into shear demixing.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 5 (1988), S. 72-76 
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Photon correlation spectroscopy (PCS) has been applied to various systems of particles suspended in a fluid. Computer simulations were used to analyse CONTIN, a program for the numerical inversion of the experimental data. Measurements were performed on a spectrometer equipped with a digital correlator. Various suspensions of polysterene latex spheres differing both in size and size distribution were prepared in double distilled water. Further some samples provided by an external institution without prior specification were analysed. Diffusivity measurements on submicron DES (di-2-ethylhexyl sebacate) particles in nitrogen were also performed. The results obtained demonstrate the strengths and the limitations of PCS as a method of determining particle size distributions in particle fluid systems.
    Additional Material: 12 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 12 (1989), S. 560-561 
    ISSN: 0935-6304
    Keywords: Hydrodynamic chromatography ; Dipalmitoylphosphatidylcholine ; Liposomes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 32 (1986), S. 139-141 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 349-361 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The corrosion behavior of commercially available copper, nickel, and gold alloys for dental castings was investigated. The alloys investigated included: three copper alloys (76-87Cu, 6-11Al, 0-12Zn, 1-5Ni, 0-4Fe, 0.5-1.2Mn). two nickel alloys (68-78Ni, 12-16Cr, 4-14Mo, 0-1.7Be), and one gold alloy (77Au, 14Ag, 8Cu, 1Pd). Anodic and cathodic polarization curves, long-term immersion tests in saline and artificial saliva solutions, and dog crown studies were conducted to evaluate both the in vitro and in vivo corrosion characteristics of the alloys. All evaluations conducted demonstrated that the copper alloys were highly susceptible to corrosion attack. High corrosion currents were observed in the in vitro tests, and SEM of the alloys specimens showed significantly altered surfaces. The anodic polarization curves predicted that the beryllium-containing nickel alloy should be susceptible to localized corrosion and SEM revealed an etched surface with corrosion of certain microstructural features. No significant corrosion was predicted or observed for the non-beryllium nickel alloy and the gold alloy. The in vitro corrosion evaluations predicted the in vivo corrosion behavior for the alloys. Since the three copper alloys and the beryllium-containing nickel alloy demonstrated significant corrosion under the tested conditions, the use of these alloys for restorative procedures is questionable due to the release of significant levels of selected ions to the oral cavity.
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