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  • 1
    Electronic Resource
    Electronic Resource
    Synthese und NMR-Spektren von Nonafulven sowie Vergleich mit 10-PhenylnonafulvenHerrn Prof. Dr. Hans Nitschmann zum 80. Geburtstag gewidmet52. Mitt. über Fulvene, Fulvalene; 51. Mitt. [1]; Kurzmitt. [2]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 862-880 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and NMR Spectra of Nonafulvene and Comparison with 10-PhenylnonafulveneExperimental procedures for the reaction of cis,cis,cis,trans-cyclononatetraenide (ccct-CNT-; see 4) with bromomethyl acetate (1a, R = H, X = Br) to give (cyclononatetraenyl)methyl acetate (5a; 84% yield) as well as for the base-induced elimination of HOAc from 5a to give nonafulvene (6a; 44% yield) are described. Spectroscopic as well as chemical evidence for 6a and 6b is presented. An approximate high-field-NMR analysis of 6a and 6b has been completed. The results are in favour of a fast interconversion of the type 6A⇄6B (Scheme 4), and supported by the MNDO-optimised geometry of 6a. The first X-ray analysis of a cyclononatetraene (i.e. of 5b) has been accomplished: 5b is a polyolefinic molecule with largely alternating bond lengths and with a nine-membered ring deviating strongly from planarity.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700327
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  • 2
    Electronic Resource
    Electronic Resource
    Festkörper-Polymerisation eines ‘Push-Pull’-Diacetylens23. Mitteilung über Aminoacryl-Derivate. 22. Mitteilung: [1]. (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 1324-1336 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solid-State Polymerisation of a ‘Push-Pull’-DiacetyleneSolid-state polymerisation of ‘push-pull’-diacetylene 5-(diphenylamino)-1-phenylpenta-2,4-diyn-1-one (1d), initiated by heating of crystals of 1d at 90°, gives ‘push-pull’ poly-diacetylene 2d. X-Ray results and spectroscopic data of monomer 1d as well as of polymer 2d are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720621
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  • 3
    Electronic Resource
    Electronic Resource
    Nonafulvalen: Synthese durch oxidative Kupplung von Cyclononatetraenid und Valenzisomerisierung53. Mitt. über Fulvene, Fulvalene; 52. Mitt. [1]; Kurzmitt. [2]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1623-1637 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nonafulvalene: Synthesis by Oxidative Coupling of Cyclononatetraenide and Valence IsomerisationFollowing a general strategy (Scheme 2) for the synthesis of fulvalenes by oxidative coupling of Hückel anions, the synthesis of nonafulvalene (1), has been realised (Scheme 3). The most tricky step is a twofold deprotonation of bi(cyclononatetraenydl) 3 with K(t-BuO) to give 4; it is only possible after equilibration 3⇄3a; otherwise, deprotonation of one cyclononatetraene unit of 3 followed by oxidative coupling with AgBF4 gives quater(cyclononatetraenyl) 12 as an isomeric mixture. The reaction of 3 with Kgives potassium cct-cyclononatetraenide 11 (M = K; Scheme 5) and not the dianion 4 as reported in the literature. Nonafulvalene (1)is extremely reactive due to its very easy valence isomerisation to geve an isomeric mixture of tetrahydro-dibenzopentafulvalenes 13 (Scheme 4). The structure of crystalline isomer (E-anti)-13 has been proved by X-ray analysis.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700620
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  • 4
    Electronic Resource
    Electronic Resource
    Synthese, 13C-NMR-Spektren und räumliche Struktur von ‘Push-Pull’-Diacetylenen22. Mitteilung über Aminoacryl-Derivate. 21. Mitteilung: [1]. (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 1914-1923 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, 13C-NMR Spectra, and X-Ray Investigation of ‘Push-Pull’ DiacetylenesPhenyl-substituted ‘push-pull’ diacetylenes 1f and 1g have been prepared by acetylation and benzoylation of the appropriate lithiodiynylamines 4 (Scheme 2). 13C-NMR spectra of diacetylenes 1a-g (Table 1) are discussed with respect to the expected polarisation of the diacetylene unit by ‘push’ and ‘pull’ substituents. X-Ray investigations of 1c, 1e, and 1f have been performed in view of the planned solid-state polymerisation of ‘push-pull’ diacetylenes. In the crystalline state, diacetylenes 1c and 1f are stacked, however, the stacking parameters do not allow a solid-state polymerisation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710810
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  • 5
    Electronic Resource
    Electronic Resource
    Dihydropentalene und 6-Vinylfulvene aus cyclopentadienylcyclopropenen. Notiz zur Umsetzung von 1,2,3-Tris[(tert-butyl)thio]cyclopropenylium-tetrafluoroborat mit cyclopentadienid (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 1506-1514 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dihydropentalenes and 6-Vinylfulvenes from Cyclopentadienyl-cyctopropenes. Reaction of 1,2,3-Tris[(tert-butyl)thio]cyclopropenylium Tetrafluoroborate with Cyclopentadienide.Reaction of 1,2,3-tris[(tert-butyl)thio]cyclopropenylium tetrafluoroborate (6a) with sodium Cyclopentadienide gives, besides of 7,8-bis{(tert-buty)thio calicene (7a), rearranged products 7,8,8-tris[(tert-butyl)thio]-6-vinylpentafulvene (9a) and 4,5.6-tris[(tert-butyl}thio]-1,2-dihydropentalene (10a)) in varying amounts depending on reaction conditions. Vinyl-carbenes 12 and 13 are supposed to be possible intermediates.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720712
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of hexacyclo[5.4.1.02,6.03,10.04,8.09,12]dodecane-5,11-dione and its conversion to di-, tri-, and tetranitro-1,3-bishomopentaprismanes (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 3782-3800 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von Hexacyclo[5.4.1.02,6.03,10.04,8.09,12]dodecan-5,11-dion und seine Umwandlung in Di-, Tri- und Tetranitro-1,3-bishomoprismaneSulfenylierung des Dianions von Dimethyl-tetracyclo[7.2.1.04,11.06,10]dodeca-2,7-dien-5,12-dicarboxylat (9) mit Dimethyldisulfid ergab das exo,exo-Bis(methylthio)-Derivat 10a. Nachfolgende Hydrolyse und oxidative Decarboxylierung führte zu Tetracyclo[7.2.1.04,11.06,10]-dodeca-2,7-dien-5,12-dion (4), ein wichtiges Zwischenprodukt. Es wurde in das Bisketal 11 übergeführt und dieses zum doppelt funktionalisierten 1,3-Bishomopentaprismen 12 photolysiert. Nachfolgende saure Hydrolyse ergab die Titelverbindung 5, woraus drei Dinitro-(14 - 16), zwei Trinitro- (20, 21) und ein Tetranitro-Derivat (22) erhalten wurden. Die Konfigurationszuordnung der ersten vier Produkte erfolgte 1H-NMR-spektroskopisch und durch Röntgenstrukturanalyse von 21. Die Stereochemie der Nitro-substituierten Käfigmoleküle wird aufgrund ihrer Bildung und ihrer Dichte diskutiert, die in vielen Fällen erhöht ist. Auch von Tetranitro-bishomopentaprisman 22 wurden die strukturellen Eigenschaften durch eine Röntgenstrukturanalyse erhellt.
    Notes: Sulfenylation of the dianion of dimethyl tetracyclo[7.2.1.04,11.06,10]dodeca-2,7-diene-5,12-dicarboxylate (9) with dimethyl disulfide delivered the exo,exo-bis(methylthio) derivative 10a. Subsequent saponification and oxidative decarboxylation resulted in transformation to tetracyclo[7.2.1.04,11.06,10]dodeca-2,7-diene-5,12-dione (4). Upon photolysis of the bisketal 11 of this pivotal intermediate, arrival at the doubly functionalized 1,3-bishomopentaprismane 12 was achieved. Following acidic hydrolysis to give the title compound 5, elaboration of three dinitro (14 - 16), two trinitro (20, 21), and a tetranitro derivative (22) was accomplished. The configurational assignment to the first four products was achieved by means of 1H NMR spectroscopy and an X-ray crystal structure analysis of 21. The stereochemistries of the nitro-substituted cage molecules are discussed in terms of the mechanism of their formation and their densities, many of which are markedly enhanced. The structural features of the tetranitro-bishomopentaprismane 22 have also been elucidated by X-ray methods.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861191222
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  • 7
    Electronic Resource
    Electronic Resource
    Eine verbesserte Methode zur Herstellung von 1,3,3-Trialkyl-2-alkylidenindolinen (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1009-1011 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Improved Method for the Synthesis of 1,3,3-Trialkyl-2-alkylideneindolinesAlkylation of 1,3,3-trialkyl-2-methyleneindolines 1a,b with iodomethane and iodomethane, respectively, under optimized reaction conditions in tetrahydrofuran provides 1,3,3-trialkyl-2-alkylideneindolines 3a-c as mixtures of (E)/(Z) isomers (yield ca. 40-50%), which can be converted into the corresponding tetrafluoroborates 5a,b. The 1H- and 13C-NMR spectra of 3a-c and 5a,b are reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210528
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  • 8
    Electronic Resource
    Electronic Resource
    A mass spectral study of cyclophosphamide concerning a thermally induced rearrangement reaction (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 163-173 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact mass spectra of cyclophosphamide (1) are very sensitive towards experimental conditions in view of the kind of sample handling, the type of mass spectrometer used and the temperature of evaporation. The reason for this phenomenon is the elimination of HCl from the molecular ion by a specific 1,5-hydrogen transfer yielding an ion at m/z 224 which is structurally related to the bicyclic compound 4 with its typical fragment ions at m/z 175 and 147. Thermal excitation of the sample increases the intensity of this fragmentation pathway. The fragmentation pattern of 1 and the thermally induced rearrangement reaction has been elucidated by means of isotopic labelling, high-resolution data, metastable ion analysis and some tandem mass spectrometric experiments. Various samples of 1 monohydrate and its commercially available preparations, which are triturates with sodium chloride, differing in the crystal size distribution, showed nearly identical mass spectra on two different magnetic mass spectrometers, provided that the materials were introduced as solids under careful control of the evaporation temperature. The fragmentation via m/z 224 prevails in case of non-crystalline, pre-dissolved samples on one of the instruments used which might be explained by a differing construction of the ion source and the sample cup holder. The conclusions of Mruzek et al. concerning different proportions of stereoisomers in pharmaceutical preparations of 1 lack any analytical evidence.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150308
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  • 9
    Electronic Resource
    Electronic Resource
    Anrißerzeugung in WC-Co-Hartmetall-Proben für die Messung des kritischen Spannungsintensitätsfaktors KIC (1989)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 20 (1989), S. 309-313 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Precracking of WC-Co-Hardmetal-Specimens for Fracture-Toughness TestingThe determination of a valid critical stress intensity factor KIC requires an extremely sharp, well defined initial crack. Methods producing such a crack are well known for metallic materials, but they often can not be used with brittle materials, like cemented carbides or ceramics. Their low fracture toughness makes a controlled crack growth under pure tensile stress nearly impossible. More useful are precracking methods, utilizing a stress gradient to stop the crack at defined depth.A very simple methods uses the indentation of a hardness tester to produce a semi-elliptical surface crack, interfered with residual stresses.For different areas of application and specimen geometries, bridge indentation, wedge indentation and composite bending method produce cracks with a straight front. Also under cyclic loading, under tensile as well as under compressive stress, the creation of a sharp precrack, applicable in KIC measurement, is possible.
    Notes: Um bei Bruchzähigkeitsmessungen einen gültigen KIC-Wert zu erhalten, sollte wegen der Abhängigkeit der Meßergebnisse vom Rißrundungsradius möglichst ein natürlich scharfer Anriß definierter Länge eingebracht werden. Methoden hierzu, wie sie aus bruchmechanischen Untersuchungen an Metallen bekannt sind, können oft bei spröden Werkstoffen, wie Hartmetall oder Keramik, nicht angewandt werden, da deren geringe Bruchzähigkeit ein kontrolliertes Rißwachstum unter reiner Zugspannung nahezu unmöglich macht.Hier bieten sich Verfahren zur Anrißerzeugung in einem Spannungsgradienten an, welcher erlaubt, einen Riß bei einer vorgegebenen Länge zu stoppen.Eine sehr einfach anzuwendende Methode nützt die Tatsache, daß sich in spröden Materialien um einen Härteeindruck ein halbelliptischer Oberflächenriß ausbildet, allerdings baut sich dabei auch ein Eigenspannungszustand auf.Für verschiedene Anwendungsbereiche und Probengeometrien können zur Erzeugung eines Anrisses mit gerader Rißfront die Brückenmethode, die Keilmethode und die Verbund-Biege-Methode eingesetzt werden. Ebenso ist es möglich, unter zyklischer Belastung, sowohl im Zug-, wie auch im Druckspannungsbereich, einen natürlich scharfen Anriß in spröden Werkstoffen zu erzeugen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19890200907
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  • 10
    Electronic Resource
    Electronic Resource
    Gas chromatographic method for simulated distillation up to a boiling point of 750°C using temperature-programmed injection and high temperature fused silica wide-bore columns (1989)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 12 (1989), S. 16-22 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Wide bore capillary columns ; Temperature programmed injection ; Simulated distillation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is demonstrated that linear injection characteristics are obtained for a wide boiling point range sample using a temperature-programmed injector in combination with wide-bore fused silica columns. The applicability of the described combination for high temperature simulated distillation is described. The method, using external standardization, gives accurate and repeatable results for different types of samples in the boiling range between 50 and 750°C. The lifetime of the fused silica wide-bore columns was found to be acceptable, viz. over 80 temperature-programmed cycles between ambient and 430°C. Some comments are made on the accuracy of boiling points for normal alkanes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240120106
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