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  • Industrial Chemistry and Chemical Engineering  (2)
  • Inorganic Chemistry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Abfangreaktionen kurzlebiger Radikale, VIII. Über die radikalische Substitution am Stickstoff: Reaktionen von 1-Aryl-triazenen mit Organozinn-hydriden (1972)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 1540-1552 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Short-Life Radicals, VIII. Radical Substitution at the Nitrogen Atom: Reactions of 1-Aryltriazenes with Organotin HydridesStannyl radicals react with 1-aryltriazenes 1-12, attacking N3 and forming stannyl amines. The reaction proceeds by an SH2α mechanism; the arylazo group is displaced (“induced degradation”) and splits off N2. This is the only reaction in cases 1-5. With 6-12, however, an SH2γ displacement predominates. Here, substituents bound to N3 are able to form fairly well stabilized radicals. Stannyl radicals attack N1, displace the substituent from N3 and form trialkylstannyl triazenes 10-12, 15, 20, which are surprisingly stable because of pentacoordination at the tin atom. The free-radical fragments abstract hydrogen from the tin hydride, releasing new stannyl radicals, which propagate the chain reaction. Hydrostannation of the azo group has not been observed. It is shown that stannyl radicals are capable of reversible addition across the azo double bond.
    Notes: Stannylradikale R3Sn⋅ können 1-Aryl-triazene 1-12 and N3 unter Bildung von Stannylaminen angreifen. Dabei wird in einer SH2α-Reaktion die Arylazogruppe verdrängt (“induzierter Zerfall”) und spaltet N2 ab. Dies tritt bei 1-5 ausschließlich ein. Bei 6-12, die an N3 einen als Radikal stabilisierten Substituenten tragen, überwiegt jedoch eine SH2γ-Reaktion. Der Angriff eines Stannylradikals an N1 verdrängt dabei den Substituenten von N3. Es entstehen Trialkylstannyl-triazene 10-12, 15 und 20, durch Pentakoordination am Zinnatom überraschend stabil. H-Abstraktion aus dem Organozinnhydrid stabilisiert die abgespaltenen Molekülfragmente. Die hinterbleibenden Stannylradikale setzen die Reaktionskette fort. Hydrostannierung der Azodoppelbindung wird nicht beobachtet. Es wird gezeigt, daß sich Stannylradikale reversibel an die Azodoppelbindung addieren können.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19721050510
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  • 2
    Electronic Resource
    Electronic Resource
    Abfangreaktionen kurzlebiger Radikale, XI. Über die radikalische Substitution am Stickstoff: Der induzierte Zerfall von 2-Tetrazenen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 2395-2407 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Short-Life Radicals, XI. Free Radical Substitution at the Nitrogen Atom: The Induced Degradation of 2-TetrazenesThe radical degradation of tetraphenyl-2-tetrazene (1a) and 1,4-dicyclohexyl-1,4-diphenyl-2-tetrazene (1b) is found to be accelerated by trialkyltin hydride. Stannyl radicals attack at N-1 or N-4. In a SH2α reaction, N2, the corresponding stannylamine and a radical ·N(R)R′ are formed. The latter is scavenged by R3SnH giving the amine; or it recombines with a stannyl radical at low hydride concentrations. Dicarbizolyldiazene 1c reacts by the same way, but not so the dipiperidinodiazene (1d). Importance of stabilization of ground and transition states on the spontaneous and the induced degradation are discussed. Values of t1/2, k, ΔH±, and ΔS± are given. Stannyl radicals also accelerate the splitting of tetraphenylhydrazine.
    Notes: Der radikalische Zerfall von Tetraphenyl-2-tetrazen (1a) und 1,4-Dicyclohexyl-1,4-diphenyl-2-tetrazen (1b) wird durch Trialkylzinnhydrid beschleunigt. Beim Angriff von Stannyl-Radikalen an N-1 oder N-4 entstehen in einer SH2α-Reaktion N2, Stannylamin und ein Radikal ·N(R)R′, das durch R3SnH zum Amin abgefangen wird oder mit einem Stannyl-Radikal bei niedriger Hydrid-Konzentration rekombiniert. Auch Dicarbazolyldiazen 1c reagiert analog, nicht jedoch Dipiperidinodiazen (1d). Einflüsse der Stabilisierung von Grund- und Übergangszustand auf den Spontan- wie den induzierten Zerfall werden diskutiert, Werte für t1/2, k, ΔH* und ΔS* angegeben. Auch Tetraphenylhydrazin wird durch Stannyl-Radikale beschleunigt gespalten.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060737
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  • 3
    Electronic Resource
    Electronic Resource
    Measurement of the Influence of Directed Particle motion on the turbulent particle deposition velocity by means of laser-doppler anemometryDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 12-15 
    Details
    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: The dry deposition of particles from the atmosphere is not well understood for reasons of surface variabilities and mutual interactions between surface and particles. However, even relatively simple influences of physical parameters have so far resisted successful parameterization, although some progress has been achieved. There is no general way to determine the relative contributions of stochastic turbulent and Brownian diffusion and directed motions (i. e. sedimentation) to the total deposition velocity since they contribute in a nonlinear manner to the total deposition velocity. The directed motion is an unknown function of atmospheric turbulence, the particle diffusion coefficient Dp and the sum of all directed particle motions by thermophoresis, diffusiophoresis, photophoresis, electrophoresis, sedimentation etc. Practically nothing is known about the action of the first three forces and even the easily accessible electrophoresis has not been considered relevant for deposition of atmospheric particles. Because it is relatively easy to change an electric field with all other parameters kept constant and measure the absolute difference in total deposition velocity the following experimental Laser-Doppler study was intended to show the feasibility of the field-changing-technique and the magnitude of the effects without quantitatively determining the electrical mobility distribution as a function of particle size.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080104
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  • 4
    Electronic Resource
    Electronic Resource
    A Sampler for Total Suspended Particulates with Size Resolution and high sampling efficiency for large particles (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 74-80 
    Details
    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: For a field intercomparison of various widely used dust samplers, a reference instrument was needed. Based on a Wide Range Aerosol Classifier (WRAC), several improvements were introduced compared with the original design including mass flow control of the samplers and the plenum air, brushless threephase blowers, hyperbolic inlets and generally a more compact design, allowing for more comfortable operation. In addition, for measurement of small particle size distributions, a Hauke high-volume, low-pressure impactor (LPI 150/0.15) was included, so that size distribution information with cuts at 0.12, 0.30, 1.19, 3.14, 10.2, 20.4, 37.4 and 60 μm could be obtained. In addition, the aspiration efficiency was measured under in situconditions and parallel measurements were performed with the two reference samplers built so that the performance was well characterized.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060112
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