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  • Articles  (46)
  • Wiley-Blackwell  (42)
  • Cambridge University Press  (4)
  • 1985-1989  (30)
  • 1970-1974  (6)
  • 1935-1939  (10)
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  • Articles  (46)
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  • 1
    Electronic Resource
    Electronic Resource
    Cycloadditionsreaktionen von Heterocumulenen, XXIX. Reaktion von Thioketenen mit Isocyanaten (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 689-699 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Heterocumulenes, XXIX.  -  Reactions of Thioketenes with IsocyanatesThe [2 + 2] cycloaddition of thioketenes 1a-f to isocyanates 2a-f yields 4-thioxo-2-azetidinones 3 as main products, which may isomerize to 4-imino-2-thietanones 5. In competing reactions, 2,4-azetidinediones 8, N-sulfonylamides 9, and 3H-1,2,4-dithiazoles 15 are formed. Thioketenes 1 react with chlorosulfonyl isocyanate (20b) to give N-unsubstituted 4-thioxo-2-azetidinones 22. Depending on the thioketene 1 and the reaction conditions, compounds 23-26 also result. The constitutions of 15b and 23a were determined by X-ray structural analyses.
    Notes: Die [2 + 2]-Cycloaddition der Thioketene 1a-f an die Isocyanate 2a-f liefert als Hauptprodukt 4-Thioxo-azetidinone 3, die sich zu 4-Imino-2-thietanonen 5 isomerisieren können. In Konkurrenzreaktionen werden 2,4-Azetidindione 8, N-Sulfonylamide 9 und 3H-1,2,4-Dithiazole 15 gebildet. Mit Chlorsulfonylisocyanat (20b) reagieren die Thioketene 1 zu N-unsubstituierten 4-Thioxo-2-azetidinonen 22. Je nach Thioketen 1 und Reaktionsführung resultieren auch die Verbindungen 23-26. Die Konstitution von 15b und 23a wurde durch Röntgenstrukturanalyse bestimmt.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210416
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  • 2
    Electronic Resource
    Electronic Resource
    1,3-Diazabutadiene: Kristallstruktur, quantenmechanische Berechnungen und spektroskopische Untersuchung (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1705-1710 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Diazabutadienes ; ab initio calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,3-Diazabutadienes: Crystal-Structure Analysis, Quantum-Mechanical Calculations, and Spectroscopic InvestigationThe X-ray analysis of derivative 3a (available from the corresponding amidine and aldehyde by titanium tetrachloride assisted condensation) shows, that the substituent at the nitrogen atom N1 prefers the (Z)position. The heterobutadiene chain is strongly twisted [Θ(N2—C7—N1—C8) = 109.7°], indicating only weak conjugative interactions between the two C=N units. The dynamic properties of 1,3-diazabutadiene (4) (N-methyleneformamidine) were simulated by ab initio calculations (3-21G, MP2/6-31G*). The global minimum corresponds to the s-trans isomer 4a with (Z) configuration at N1 = C2; a gauche form (local minimum) 4c is slightly higher in energy. For the (E)-N1=C2 isomers, gauche structure 4d is lowest in energy, the s-trans form 4b is less favourable by 2-3 kcal/mol. The calculated rotational barriers (2-7 kcal/mol) are similar to those of butadiene. Inversion processes also have low barriers: Transition structures with linear, sphybridized nitrogen atoms N3 and orthogonal positions of the N3=C4 unit were found (Erel ≍ 20 kcal/mol). IR1H-, 13C-NMR, and UV data are given and compared with the results of the structural investigations.
    Notes: Die Kristallstrukturbestimmung des durch Kondensation des entsprechenden Amidins unter Aldehyds Titantetrachlorid-Zusatz erhältlichen Derivates 3a zeigt, daß sich der Substituent am Stickstoff-Atom N1 in der (Z)-Position befindet. Das Heterobutadien-Gerüst fällt durch seinen großen Torsionswinkel [Θ(N2—C7—N1—C8) = 109.7°] auf und läßt auf nur schwache konjugative Wechselwirkungen zwischen den beiden C=N-Einheiten schließen. Die dynamischen Eigenschaften von 1,3-Diazabutadien (4) (N-Methylenformamidin) wurden durch ab-initio-Berechnungen (3-21 G, MP2/6-31G*) simuliert. Demnach ist die günstigste Struktur die s-trans-Form 4a mit (Z)-Konfiguration an N1 = C2; daneben existiert ein gauche-Minimum 4c mit geringfügig höherer Energie. Für die (E)-N1=C2-Konfiguration ist die gauche-Form 4d am energieärmsten, die s-trans-Struktur 4b entspricht einem lokalen Minimum (Erel ≍ 2-3 kcal/mol). Die berechneten Rotationsbarrieren (2-7 kcal/mol) sind denen von Butadien vergleichbar. Auch Inversionsprozesse an N3 haben niedrige Barrieren: Es konnten Übergangszustände mit linearem, sphybridisiertem Stickstoff-Atom N3 und orthogonaler Stellung der N3=C4-Einheiten ermittelt werden (Erel ≍ 20 kcal/mol). IR1H-, 13C-NMR- und UV-Daten werden zugeordnet und mit den Strukturergebnissen verglichen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220917
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  • 3
    Electronic Resource
    Electronic Resource
    Über das Reaktionsverhalten von 4-Thioxo-2-azetidinonen (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 701-707 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Reactivity of 4-Thioxo-2-azetidinonesBase-catalyzed alcoholysis of the N—S bond in N-sulfonylthioxoazetidinones 1 is a ready process; the resulting sulfonate then alkylates the liberated 2-. Alkylations of 2 under various conditions demonstrate that charge and thermodynamic control favor attack on nitrogen to give 5 rather than reaction on sulfur to give 4. Besides simple alkyl residues (4a-c, 5a-c) also functionalized alkyl (4d, e, g, m, n, o, 5d, e, g, i, m-o), aryl (5p), and acyl groups (5q) can be introduced and addition reactions (5r, s) achieved. Complex hydrides reduce the carbonyl group in 1,5 to yield 8-10, but the C=N+ unit in the salt 6a to furnish β-lactam 11. Annulation of a five-membered ring to give 12 is achieved by 1,3-dipolar cycloaddition of dimethyl fumarate to in-situ generated azomethine ylide 6d.
    Notes: Die basenkatalysierte Alkoholyse der N—S-Bindung in N-Sulfonyl-thioxoazetidinonen 1 tritt leicht ein; der entstehende Sulfonsäureester alkyliert dann das freigesetzte 2-. Unter verschiedenen Bedingungen durchgeführte Alkylierungsreaktionen an 2 zeigen, daß Ladungs- und thermodynamische Kontrolle den Angriff am Stickstoff zu 5 gegenüber der Reaktion am Schwefel zu 4 begünstigen. Neben einfachen Alkyl-Resten (4a-c, 5a-c) lassen sich auch funktionalisierte Alkyl-(4d, e, g, m, n, o, 5d, e, g, i, m-o), Aryl- (5p) und Acyl-Gruppen (5q) einführen sowie Additionsreaktionen (5r, s) erreichen. Komplexe Hydride reduzieren die Carbonyl-Gruppe in 1, 5 zu 8-10, aber den C=N+-Teil im Salz 6a zum β-Lactam 11. Die Anellierung eines Fünfrings zu 12 gelingt über die 1,3-dipolare Cycloaddition von Fumarsäure-dimethylester an das in situ freigesetzte Azomethin-Ylid 6d.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210417
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  • 4
    Electronic Resource
    Electronic Resource
    Notiz zum Problem des Substituentenaustausches bei der Grignard-Alkylierung von PhenylsilanenDie vorliegende Notiz ist als Diskussionsbeitrag zum Thema „Austauschreaktionen bei Organometallverbindungen“ gedacht. Das behandelte Problem wird von uns experimentell nicht weiter verfolgt. (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 1302-1305 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701030434
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  • 5
    Electronic Resource
    Electronic Resource
    Melting, crystallization, and solution behavior of chain molecules with hydrocarbon and fluorocarbon segments (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 911-925 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Melting, crystallization, and solution behavior of n-alkanes with fluorocarbon segments of twelve carbon atoms on one end, F(CF2)12(CH2)nH, or on both ends, F(CF2)12(CH2)n(CF2)12F were investigated by DSC, MAS 13C NMR, light scattering, and birefringence studies. Both triblock F(CF2)m(CH2)n(CF2)mF and diblock F(CF2)12(CH2)nH compounds with 4 ≦ n ≦ 14 melt by a two-step process. In the first step, the alkyl segment conformations gain nearly liquid like trans/ gauche ratios, while the perfluorinated segments remain ordered. “Gels” which incorporate the entire solvent are formed by crystallization from even dilute solutions of hydrocarbon and fluorocarbon solvents. The gels are built up of extremely long, interdigitated needles of the pure solute. Due to the bilayer structures and different degrees of ordering of the hydrocarbon and the fluorocarbon segments, the crystals grow preferentially in the direction parallel to the lamellar surface. Light scattering experiments in octane demonstrated the formation of micelle type associates.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890422
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  • 6
    Electronic Resource
    Electronic Resource
    Formulation and solution of hierarchical finite element equations (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1213-1233 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper presents a general hierarchical formulation applicable to both elliptic and hyperbolic problems. Static and eigenvalue linear elastic problems as well as convection-diffusion problems are studied. The hierarchical formulation is well suited for adaptive procedures.For the convection-diffusion problem the hierarchical approximation is made in time only. Different hierarchical functions are proposed for different types of problems. Both weighted residual and least-squares formulations are applied. A combination of these two gives a penalty method with a constraint equation corresponding to the least-squares method. A whole class of time integration formulae is obtained. These are all suitable for adaptive procedures owing to the hierarchical approximation in the time domain. If a linear discontinuous hierarchical base function is used in the Galerkin weak formulation, the method so obtained corresponds to the discontinuous Galerkin method in time and is especially suited for convection dominated problems. The streamline-diffusion method is found to be the aforementioned penalty method.This paper also examines the sequence of nested equation systems that results from a hierarchical finite element formulation. Properties of these systems arising from static problems are investigated. The paper presents some new possibilities for iterative solution of hierarchic element equations, and different procedures are compared in a numerical example. Finally, a simple ID convection-diffusion problem clearly shows that the proposed hierarchical formulation in time gives a stable and accurate solution even for convection dominated flow.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260514
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  • 7
    Electronic Resource
    Electronic Resource
    Phase transitions and defect structure in the lamellar surface of polyethylene and n-alkane crystallites. Magic angle spinning 13C NMR studiesHerrn Professor Dr. R. Kosfeld zum 60. Geburtstag gewidmet (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1237-1252 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Variable temperature magic angle spinning 13C NMR experiments on linear alkanes and low molecular weight polyethylene allowed the observation of up to six carbon atoms at the chain ends near the surface of the lamellar crystallites. Conformational order-disorder and intermolecular packing effects are reflected by the spectra. The effects are discussed with regard to the peculiar phase behaviour of the n-alkanes and the fringed micella model for low molecular weight polyethylene. The solid-solid transitions of nonadecane and hexatriacontane appear to be correlated with the occurrence of specific non-liquid-like conformational disordering. Thus, conformational defects were observed for the “rotator phase” which depend on the chain length and which vary along the chain. Whilst the center part of the chain remains all-trans ordered, significant gauche defects were observed for the bonds at the chain ends. For a polydisperse low molecular weight linear polyethylene as well as for monodisperse octahexacontahectane reversible liquid-like conformational disordering of the terminal chain segments could be detected when the melting point was approached. Hence, in this case the NMR spectra indicate pre-melting of the lamella surface, while in case of the shorter n-alkanes the occurrence of end-gauche defects is correlated with solid-solid transitions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021870520
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  • 8
    Electronic Resource
    Electronic Resource
    Poly(2-vinylpyridine) block copolymers. Phase separation and electric conductivity of iodine complexesDedicated to Prof. Dr. H.-J. Cantow on the occasion of his 65th birthday (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 1153-1168 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of AB diblock copolymers of poly(2-vinylpyridine) (P-2VP) and either polybutadiene or polystyrene were prepared in a nonpolar solvent at low temperature. Well-defined polymers with narrow molecular weight distributions were obtained and electron micrographs showed that these block copolymers form a well-separated two-phase morphology. Percolation of P-2VP domains could be achieved for samples with 40 and with 60 mol-% of P-2VP blocks. These samples were modified by addition of various amounts of iodine in solution and in the melt. Electric conductivities of the doped composites were determined by the four-probe method. The conductivities of the two phase systems were, in general, lower than that of P-2VP doped with I2.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1989.021900521
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  • 9
    Electronic Resource
    Electronic Resource
    Die Einwirkung von Kohlenoxyd auf ammoniakalische Cuprisalzlösungen. II. Mitteilung: Kohlenoxyd und Kupfer-2-amminverbindungen in Gegenwart von metallischem Kupfer (1935)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 224 (1935), S. 130-152 
    Details
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die Absorption von Kohlenoxyd in Cupritetramminsalzlösungen, z. B. Cupritetramminhydroxyd, -carbonat, -chlorid, -sulfat wird durch die Gegenwart metallischen Kupfers außerordentlich beschleunigt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19352240203
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  • 10
    Electronic Resource
    Electronic Resource
    Die Einwirkung von Kohlenoxyd auf ammoniakalische Cuprisalzlösungen. I. Mitteilung: Kohlenoxyd und Kupfer-2-amminverbindungen unter Ausschluß von metallischem Kupfer (1935)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 224 (1935), S. 113-129 
    Details
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1. Kohlenoxyd wird von Cupritetramminverbindungen, z. B. Cupritetramminhydroxyd, -carbonat, -acetat, -chlorid, -sulfat, -nitrat, in wäßrig-ammoniakalischen Lösungen aufgenommen unter Bildung von Kohlendioxyd, das zu Carbonat gebunden wird und in der Lösung verbleibt. Die Absorption des Kohlenoxyds, die zunächst langsam vor sich geht, wird dann durch autokatalytische Vorgänge wesentlich beschleunigt. Alles Cuprisalz wird in Cuprosalz übergeführt unter Entfärbung der Lösungen, die schließlich Cuproammincarbonat und dasjenige Cuproamminsalz enthalten, das dem ursprünglich angesetzten Cupriamminsalz entspricht.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19352240202
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