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  • Inorganic Chemistry  (5)
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  • 1
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensed Ring Systems, XVI1). Synthesis, Crystal and Molecular Structure of a 1,4-Bridged Dewar-Benzene of the [6.2.2]Propellane Series with Conformational EnantiomerismStarting from 3,4:5,6-dibenzo-10,13-dithia[6.3.3]propella-3,5-diene (1) racemic 3,4:5,6-dibenzo-[6.2.2]propella-3,5,9,11-tetraene (7) is prepared. Its constitution is established by X-ray structure analysis. An enantiomeric enrichment of 7 has been achieved by chromatography on triacetyl cellulose; its halflife at 20°C is about 100 h.
    Notes: Ausgehend von 3,4:5,6-Dibenzo-10,13-dithia[6.3.3]propella-3,5-dien (1) wird das racemische 3,4:5,6-Dibenzo[6.2.2]propella-3,5,9,11-tetraen (7) hergestellt. Seine Konstitution wird röntgenstrukturanalytisch bewiesen. Durch Chromatographie an Triacetylcellulose konnte eine Anreicherung der Enantiomeren von 7 erreicht werden, deren Halbwertszeit bei 20°C ca. 100 h beträgt.
    Additional Material: 1 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 967-972 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Crystal and Molecular Structure of 1,1,3,3-Bis(1′,1′,5′,5′-tetramethylpentamethylene)alleneThe symmetrically substituted allene derivative 1,1,3,3-bis(1′,1′,5′,5′-tetramethylpentamethylene)allene (4) crystallizes in the monoclinic space group P21/c with Z = 4 molecules in the unit cell. The deviation of 2.4° from the linear arrangement of the allene group is produced by different interactions with the equatorial methyl substituents.
    Notes: Das symmetrisch substituierte Allenderivat 1,1,3,3-Bis(1′,1′,5′,5′-tetramethylpentamethylen)allen (4) kristallisiert in der monoklinen Raumgruppe P21/c mit Z = 4 Molekülen in der Elementarzelle. Die Abweichung von 2.4° aus der linearen Anordnung der Allengruppierung ist durch ihre unterschiedlichen Wechselwirkungen mit den äquatorialen Methylsubstituenten bedingt.
    Additional Material: 3 Ill.
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  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensed Ring Systems, XV. About the Reaction of α-Chloro Sulfoxides with Potassium tert-Butoxide by the Example of the Synthesis of OxapropellenesThe synthesis of dithia- 1a - 3a and oxathiapropellenes 1b - 3b is described. From 1b - 3b the α-chloro sulfoxides 4 - 6 and α-chloro sulfones 4a - 6a are prepared, or which in most cases several stereoisomeric racemates are obtained. The constitution, configuration, and conformation of the α-chloro sulfoxide 4, the main product obtained from 1b, was elucidated by X-ray structure analysis. Only in that way it was possible to deduce the constitutions and configurations of the other stereoisomeric α-chloro sulfoxides 4 - 6 and α-chloro sulfones 4a - 6a, respectively, using 13C NMR spectroscopy. By the reaction of the α-chloro sulfones 4a - 6a with potassium tert-butoxide (Ramberg-Bäcklund reaction) the corresponding oxapropellenes 7 - 9 are obtained only in low yields (〈 10%). Contrary, the α-chloro sulfoxides 4 - 6, und analogous conditions give yields of 80 - 90% (from 4, 6) and 25% (from 5).
    Notes: Es wird die Synthese der Dithia- 1a - 3a und Oxathiapropellene 1b - 3b beschrieben. Aus 1b - 3b werden die α-Chlorsulfoxide 4 - 6 und α-Chlorsulfone 4a - 6a hergestellt, von denen meist mehrere stereoisomere Racemate erhalten werden. Konstitution, Konfiguration und Konformation des Hauptprodukts der aus 1b erhaltenen α-Chlorsulfoxide 4 wurden durch Röntgenstrukturanalyse ermittelt. Erst dadurch wurde es möglich, mit Hilfe der 13C-NMR-Spektroskopie die Konstitutionen und Konfigurationen der anderen stereoisomeren α-Chlorsulfoxide 4 - 6 und α-Chlorsulfone 4a - 6a aufzuklären. Bei der Reaktion der α-Chlorsulfone 4a - 6a mit Kalium-tert-butylat (Ramberg-Bäcklund-Reaktion) erhält man die entsprechenden Oxapropellene 7 - 9 nur in geringer Ausbeute (〈 10%), während die α-Chlorsulfoxide 4 - 6 unter analogen Bedingungen Ausbeuten von 80 - 90% (aus 4, 6) und 25% (aus 5) ergeben.
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  • 4
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 59. Unusual Preparation as well as Crystal and Molecular Structure of Trimethyl 3,4,5-Tri-tert-butylprismane-1,2,6-tricarboxylateIrradiation of Dewar benzene derivative 3 leads to prismane 4 with an unexpected substitution pattern. The X-ray structure analysis of 4 shows a long [1.555(3) Å] bond in the tert-butylated and a short [1.521 (3) Å] bond in the methoxycarbonyl-substituted threemembered ring. The bond distance for the connecting bonds is 1.560(3) Å.
    Notes: Belichtung von Dewarbenzol-Derivat 3 führt zu Prisman 4 mit einem unerwarteten Substitutionsmuster. Die Röntgenstrukturanalyse von 4 zeigt eine lange [1.555(3) Å] und eine kurze [1.521 (3) Å] Bindung im tert-Butyl- bzw. Methoxycarbonyl-substituierten Dreiring. Der Abstand für die die Dreiringe verknüpfenden Bindungen beträgt 1.560(3) Å.
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  • 5
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensed Ring Systems, XVII. Propellanes with Benzene-Dewar-Benzene Structure  -  Crystal and Molecular Structure of 1′,8′:3,5-Naphtho[5.2.2]propella-3,8,10-trieneThe syntheses of the propellanes 7-9, which have a benzene-Dewar-benzene structure, are described. As a second example of a 1,4-bridged Dewar-benzene, the crystal and molecular structure of 1′,8′:3,5-naphtho[5.2.2]propella-3,8,10-triene (9) is elucidated by X-ray structure analysis. 9 has a long central bridge bond of 1.565 Å, which, however, is clearly shorter than the corresponding bond of 3,4:5,6-dibenzo[6.2.2]propella-3,5,9,11-tetraene (10: 1.586 Å), due to the smaller C5-bridge. The dihedral angle of 116.6° between the cyclobutene rings of the Dewarbenzene system of 9 is insignificantly larger than the analogous angle of 10 (115.9°). The molecule lies on a crystallographic mirror plane.
    Notes: Die Synthesen der Propellane 7-9, die eine Benzol-Dewarbenzol-Struktur besitzen, werden beschrieben. Als zweites Beispiel für ein 1,4-überbrücktes Dewarbenzol wird die Kristall- und Molekülstruktur von 1′,8′:3,5-Naphtho[5.2.2]propella-3,8,10-trien (9) mittels Röntgenbeugung bestimmt. 9 besitzt eine lange zentrale Brückenbindung mit 1.565 Å, die jedoch aufgrund der kleineren C5-Brücke deutlich kürzer als die entsprechende Bindung im 3,4:5,6-Dibenzo[6.2.2]-propella-3,5,9,11-tetraen (10: 1.586 Å) ist. Der Faltungswinkel zwischen den beiden Cyclobutenringen des Dewarbenzol-Systems beträgt 116.6° und ist damit nur unwesentlich größer als der von 10 (115.9°). Das Molekül liegt auf einer kristallographischen Spiegelebene.
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