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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 137-144 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational barriers of the dimethylamino group in different enamino aldehydes and ketones have been applied for evaluation of their conformation. It has been maintained that repulsion between bulky substituents causes twisting of the molecule rather than planar deformations. Arguments for and against these alternative concepts based on the analysis of JHH and J(13CH) coupling constants in different fragments of the molecule have been discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 189-193 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. i 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. ii 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 203-228 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new theory6 for ‘ring current’ effects on the chemical shifts of protons in or out of the plane of a benzene ring is summarized, and pictorially compared with the predictions of the earlier semi-classical theory of Johnson and Bovey.1 In the Appendix are presented extensive numerical tables of the predicted shieldings.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 237-246 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H and 13C NMR spectra of antibiotic Viomycin sulphate and its constituent aminoacids in H2O and D2O were examined in a wide range of pH values. The spectra were analysed by proton spin-spin decoupling experiments and measurements of the relative intensities of the resonance and chemical shift values. Exchange experiments were also carried out and an almost complete assignment of the resonances of the spectra was possible. The data obtained are discussed in terms of possible structures for Viomycin and the presence of intramolecular hydrogen bonds. Some information about the conformation of the molecule is also given. A tentative assignment of the 13C spectrum of Viomycin is given and the experimental 13C chemical shift values compare well with the theoretical ones evaluated by Grant's rule.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 283-308 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of substituted hexahydropyrido [2,1-c][1,4]oxazin-4(3H)-ones has been prepared by reaction of the sodio derivative of the appropriate piperidyl carbinol with ethyl chloroacetate. From a study of their NMR spectra the configurations of these compounds have been assigned and the conformation of the perhydro-1, 4-oxazinone moiety shown to be that with the ring oxygen atom and the angular hydrogen on the same side of the plane defined by C3—C(O)—N. The synthesis and NMR spectra of hexahydro-2H-pyrido [1,2-d][1,4]oxazepin-5(4H)-one, 1,6,11,11a-tetrahydro [1,4]-oxazino [4,3-b]isoquinolin-4(3H)-one and of hexahydropyrido [2,1-c][1,4]thiazin-4(3H)-one are also discussed. cis-6,9a-H-6-Methyl-hexahydropyrido[2,1-c][1,4]oxazin-4(3H)-one is shown to exist in a conformation containing a deformed perhydropyridine ring.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 327-333 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The NMR spectra of ten disubstituted amides have been recorded at 0°C in carbon tetrachloride and in benzene solutions. The benzene dilution shifts (ASIS) and proton spin decoupling were used to make the chemical shift assignments. A time-averaged solvent cluster model for the association between the amide and benzene is consistent with the observed ASIS values. The assignments for the N-methine and N-methyl resonance peaks in RCON[CH(CH3)2]2, where R is methyl, ethyl or propyl are inverted from the assignments for N,N-diisopropylformamide (R = H).
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 361-363 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 1 (1969), S. 451-465 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The confromations of the unsaturated seven membered ring in 4,4,6,6-tetradeuterium-1,2-benzocycloheptene-(1) (1) and five benzocycloheptene derivatives were determined by NMR spectroscopy. For all investigated compounds at -80°C only one conformer was present in detectable quantity. By analysis of the NMR data - molecular symmetry, coupling constants and chemical shift - it can be shown that the conformation is always the chair form. The free conformational enthalpy of both the other conformations with boat or twist form of the ring is for all six compounds more than 1.8 kcal/mole.The experimental results agree with those from model calculations: thus for benzocycloheptene, the 5,5-dimethyl derivative (2) and the 4,4,6,6-tetramethyl derivative (4) the lowest energy was found for the chair conformation; the second most stable conformations were found to be the boat for 1 and 4, and the twist form for 2.
    Notes: Für 4.4.6.6-Tetradeuterium-1.2-benzocyclohepten-(1) (1) und fünf Benzocyclo-heptenderivate wurde PR-specktroskopisch die Konformation des ungesättigten Siebenringes bestimmt. Bei allen untersuchten Verbindungen liegt bei -80° nur ein Konformeres in nachweisbarer Menge vor. Durch Auswertung PR-spektroskopisch bestimmter Daten - Molekel-Symmetrie, Kopplungskonstanten, chemische Verschiebungen - kann gezeigt werden, daß dieses Konformere Sesselform hat. Die freie Konformationsenthalpie der beiden anderen Konformeren mit Wannen- bzw. Twist-Form des Siebenringes beträgt bei allen sechs Verbindungen mehr als 1,8 kcal/Mol.Mit den experimentellen Ergebnissen stimmen diejenigen von Modellrechnungen überein: Für die Molekeln des Benzocycloheptens sowie des 5.5-Dimethylderivates (2) und der 4.4.6.6-Tetramethylverbindung (4) wurde für die Sesselkonformation der niedrigste Energieinhalt berechnet; als zweitstabilste Konformation wurde bei 1 und 4 die Wanne, bei 2 hingegen die Twist-Form ermittelt.
    Additional Material: 2 Ill.
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