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  • Springer  (46)
  • American Institute of Physics (AIP)  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 7854-7861 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The 7Li relaxational behavior of phenyl-lithium in isotropic solution has been investigated. The multiexponential quadrupolar relaxation dynamic facilitates the determination of the rotational diffusion constants together with the quadrupolar coupling constant, despite the zero average of the quadrupolar splitting on account of molecular tumbling. The rotational diffusion constants obtained are in very satisfactory agreement with those derived from our phenyl-lithium 13C relaxation studies.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 2723-2726 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: It will be demonstrated that the chemical shift anisotropy (CSA) relaxation mechanism for protonated aromatic 13C nuclei is by no means negligible. The cross correlation spectral density arising from dipolar and CSA interactions in the natural abundance 13C–H spin system of pentachlorobenzene is included in the complete determination of the molecular motional anisotropy. Additionally, the absolute sign of the indirect coupling constant 1JCH is shown to be positive.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 103 (1972), S. 615-623 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Fragmentation von β-Lactamen ergibt massenspektroskopisch sowie thermisch entweder die Ausgangsverbindungen Keten und Azomethin oder bevorzugt Äthylene und Isocyanate. Dabei brechen jeweils zwei gegenüberliegende Bindungen. Eine Berechnung der Überlappungsenergien im Ring mittels der EHT-Methode zeigt, daß der induktive Einfluß der Substituenten die Richtung des Zerfalls bestimmt. Es kann auch bei anderen Vierring-Ketonen eine bevorzugte Fragmentation des Ketenbestandteiles nachgewiesen werden.
    Notes: Abstract Both mass spectroscopic and thermal fragmentation of β-lactams yield either the reactants (ketenes and azomethines), or preferentially ethylenes and isocyanates. In each case two opposite bonds are broken. Calculation of the overlap energies in the ring by the EHT method shows that the direction of fragmentation is determined by the inductive influence of the substituents. Preferential fragmentation of the ketene constituent can also be demonstrated in other four-membered ring ketones.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 103 (1972), S. 1253-1261 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Es wird gezeigt, daß Aniline, die in 2-bzw. 2,6-Stellung halogensubstituiert sind, mit Phenalentrion (PT) in Xylol oder Eisessig zu den entsprechenden 7H,8H-Naphtho[1,8−bc]-phenoxazin-7-on-derivaten reagieren. Die analoge Umsetzung mit 2,6-Dimethyl-bzw. 2,6-Diäthyl-anilin in Xylol führt zu Oxazepinen, während in Eisessig bevorzugt Addition des zur NH2-Gruppe in p-Stellung befindlichen H-Atoms an die mittelständige C=O-Gruppe desPT stattfindet. Es wird experimentell bewiesen, daß diese Ringschlußreaktion über primär gebildete Halbaminale abläuft.
    Notes: Abstract o-Halogenated (o,o′-dihalogenated) anilines react with phenalenetrione (PT) in boiling xylene or acetic acid to give 7H,8H-naphtho[1.8−bc]phenoxazin-7-one derivatives. The analogous reaction with 2.6-dimethyl-or 2.6-diethyl-aniline in xylene gives oxazepines, while in acetic acid preferential addition of the aniline with the para position to the NH2-group to the central C=O-group ofPT occurs. It can be shown, that the first step in the ring closure reaction is the formation of semiaminales.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 103 (1972), S. 1453-1464 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Injiziert man Ratten i. p. 1,1-Diäthoxy-4-hydroxy-2-penten, so wird die Verbindung rasch resorbiert und metabolisiert. Im Harn können 6 Metaboliten nachgewiesen werden. Zwei davon wurden als diastereomere Mercaptursäuren identifiziert, nämlich als die N-Acetyl-S-(d-bzw.l-1-diäthoxymethyl-3-oxobutyl)-l-cysteine. Der Bildungsweg dieser Verbindungen wird besprochem.
    Notes: Abstract Following intraperitoneal administration to rats 1.1-diethoxy-4-hydroxy-2-pentene is rapidly resorbed and metabolized. Among six metabolites excreted in rat urine two have been identified as the diastereomeric mercapturic acids, N-acetyl-S-(d-1-diethoxymethyl-3-oxo-butyl)-l-cysteine and N-acetyl-S-(l-1-diethoxymethyl-3-oxobutyl)-l-cysteine. The metabolic formation of these compounds is discussed.
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  • 6
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract The temperature dependence of the transanular tautomerism is shown by IR and NMR spectroscopic methods.
    Notes: Zusammenfassung Durch IR-und NMR-spektroskopische Untersuchungen wird eine Temperaturabhängigkeit der Transanulartautomerie nachgewiesen.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 100 (1969), S. 1604-1607 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract A nuclear magnetic resonance investigation confirms the existence of three different phenolphthalein anions in aqueous alkali.
    Notes: Zusammenfassung Kernrescnanzspektroskopische Untersuchungen bestätigen das Vorliegen dreier verschiedener Formen des Phenolphthaleins im alkalischen Medium.
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  • 8
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Di-tert.-butyl-thiodiimine (1) adds malonyl chloride yielding 4-tert.-butyl-5-chloro-7.7-dimethyl-3-oxo-6-thia-4.6-diaza-5-octenoyl chloride, characterized as dianilide2. The chlorides of benzyl-, methyl-, ethyl-, and isopropyl malonic acid react with1 via the corresponding intermediates with loss of 2 HCl to give derivatives of 3.5-dioxo-1.2.6-thiadiazine3–6. The reaction of1 with phenylmalonyl chloride gives 2.5-di-tert.-butyl-4-oxo-3-phenyl-1.2.5-thiadiazolidine-3-carboxyl chloride, characterized as ethyl ester7. Upon acidic hydrolysis the 3.5=dioxo-1.2.6-thiadiazines3 and6 are rearranged yielding derivatives of 1.3-dioxo-isothiazolidine (11 and12).
    Notes: Zusammenfassung Di-tert.-butyl-schwefeldiimin (1) reagiert mit Malonylchlorid unter Addition zum 4-tert.-Butyl-5-chlor-7,7-dimethyl-3-oxo-5-thia-4,6-diaza-5-octensäurechlorid, welches als Dianilid2 charakterisiert worden ist. Aus1 und den Chloriden der Benzyl-, Methyl-, Äthyl- sowie Isopropylmalonsäure entstehen über die entsprechenden chlorhaltigen Zwischenprodukte durch Verlust von 2 Mol HCl Derivate des 3,5-Dioxo-1,2,6-thiadiazins3–6. Die Umsetzung von1 mit Phenylmalonylchlorid führt zum 2,5-Di-tert.-butyl-4-oxo-3-phenyl-1,2,5-thiadiazolidin-3-carbonsäurechlorid, das sich in Form des Äthylesters7 isolieren läßt. Die 3,5-Dioxo-1,2,6-thiadiazine3 und6 lagern sich bei der sauren Hydrolyse zu den Derivaten11 und12 des 1,3-Dioxoisothiazolidins um.
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  • 9
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract The temperature and solvent dependence of the enolisation of 2-substituted cyclohexanones has been demonstrated by IR- and NMR-spectroscopic methods. A structure with endocyclic double bond is favorised for 2-Acetylcyclohexanone (2).
    Notes: Zusammenfassung Mit Hilfe von IR- und NMR-spektroskopischen Methoden werden die temperatur- und lösungsmittelabhängigen Veränderungen des Enolisierungsgrades von 2-substituierten Cyclohexanonen aufgezeigt; gleichzeitig wird die Struktur mit endocyclischer Doppelbindung für das enolisierte 2-Acetylcyclohexanon (2) erhärtet.
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  • 10
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract An IR- and NMR-spectroscopic investigation of quinoxalines and benzoxazines showed a dependence of the tautomeric equilibrium on substituents, solvents and temperature.
    Notes: Zusammenfassung IR- und NMR-spektroskopische Untersuchungen an in 2-Stellung substituierten Chinoxalinen und Benzoxazinen zeigen, daß das tautomere Gleichgewicht derselben von Substituenten, Lösungsmitteln und Temperaturen abhängig ist.
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