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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 7 (1975), S. 298-305 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H NMR spectra of substituted cyclotrisilazanes are discussed in terms of conformational analysis. Experimental spectra are consistent with an equilibrium involving chair conformers, following from simulating the effect of phenyl substituents and the temperature dependence of methyl proton chemical shifts. The barrier to chair-chair interconversion in hexamethyl-cyclotrisilazane is estimated. An analysis is carried out of the shielding of non-equivalent methyl groups in substituted cyclotrisilazanes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 52 (1961), S. 257-276 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 30 (1958), S. 513-524 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A synthesis of polyorganosiloxanes is based on attaching organic groups to inorganic silicon-oxygen chains structurally corresponding to the quartz molecules. The extension of this idea to skeletons composed of silicon, oxygen, and metals, and corresponding structurally to the silicates, led to the synthesis of new polymers containing chains such as called polyorganometalosiloxanes. Further development of the idea of attaching organic groups to mineral chains, especially the use of the groups R3SiO - , allowed the inclusion even of elements which do not form stable bonds with carbon. This paper presents some results of our research on the formation of new polymers with mineral chain molecules containing atoms of aluminum, titanium, phosphorus, and oxygen. The reactions leading to the formation of aluminosiloxanes are expressed by the following schematic equations: Titanosiloxanes are formed as follows: Similarly mixed phosphoaluminosiloxane polymers are prepared: Thus carbon and silicon are no longer the only important elements forming polymer chains. Such elements as aluminum, titanium, phosphorus, and many others belonging to the second, third, fourth, and fifth groups of the Periodic System can be used in the synthesis of polymers. The method of organically enveloping inorganic skeletons makes it possible to change the properties of the compounds within wide limits. Silicates, corundum, and inorganic polytitanates are familiar as hard, brittle compounds, insoluble in organic solvents. If now, while preserving the polymer chains typical of these inorganic molecules, we surround them by organic groups, we obtain synthetic polymers with properties markedly different from those of their inorganic analogs. At a certain stage these polymers become soluble in organic solvents, form films typical for organic polymers, and show plasticity. The organic radicals surrounding the inorganic chains increase the flexibility of the molecular chains and confer the elastic properties of typical organic macromolecular compounds on these polymers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 55 (1961), S. 89-94 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrolytic condensation of trialkylsiloxane derivatives of the formula (R3SiO)n Me leads to the formation of an oxanometallic chain and trialkylsiloxane groups within the framework of the main chain. The formation of polymers by this mechanism is due to the hydrolytic cleavage of the metallic atom from the trialkylsiloxane group. The subsequent stability of the polymer formed to the action of water will depend also upon the hydrolytic stability of the trialkylsiloxane residues. In order quantitatively to evaluate the rate of hydrolytic cleavage of the trialkylsiloxane group from the various trialkylsiloxane derivatives a viscometric method was employed in which changes in viscosity of solutions of the compounds were followed with respect to duration of the hydrolysis and concentration of the reactants. From the changes in viscosity of the solutions the rate of hydrolysis of the compounds and the values of the hydroytic stability constants could be calculated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1H-NMR Studies on Substituted 1,5-Disilapentanes and 1-Oxa-2,6-DisilacyclohexanesThe chemical shifts of the title-compounds are given. Considering the cyclic compounds as models of a linear siloxane with fixed geometry some new informations on the structure of these compounds as well as the electronic character of the Si—O—Si bond in siloxanes emerge. It is shown, that the oxygen-functionality of the siliconatom has a considerable lower influence to the chemical shifts of the Si—CH3 groups compared with that of chlorine. An explanation is presented with regard to inductive and (p→d)π effects.
    Notes: Die 1H-NMR-Spektren einiger substituierter 1,5-Disilapentane und 1-Oxa-2,6-Disilacyclohexane werden mitgeteilt und bezüglich Struktur und Bindungsverhältnissen am Si-Atom diskutiert. Es zeigt sich, daß die cyclischen Verbindungen in ihren sterischen Eigenschaften modellmäßig als lineare Siloxane mit fixierter Geometrie aufgefaßt werden können. Der geringe Einfluß, den die Sauerstoff-Funktionalität des Si-Atoms auf die chemischen Verschiebungen der Si—CH3-Gruppen ausübt, kann auf stärkere (p → d)π-Anteile in der Si—O-Bindung, verglichen mit der Si—Cl-Bindung, zurückgeführt werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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