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  • 1960-1964  (7)
  • 1
    Electronic Resource
    Electronic Resource
    17O-Kernresonanz Untersuchungen an Benzofurazanoxid (1962)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 45 (1962), S. 504-506 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 17O-NMR spectra of benzofurazan oxide at room temperature show two resonance lines. This adds evidence to support the N-oxide structure to be correct. The 17O spectra are dependent on temperature, due to an equilibration. The average lifetime of the tautomers is of the order of 10-4 s at + 45°C. The activation energy of the equilibrium is found to be 17,2 ± 1,5 kcal/mole and the frequency factor is 3 · 1014 to 3 · 1016 s-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19620450213
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Die Analyse «scheinbar einfacher» kernmagnetischer Resonanzspektren (1964)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 47 (1964), S. 1-7 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of observed spectra that give less than the theoretical number of transitions, i.e. apparently simple spectra, is studied. The general conditions for the existence of such spectra of the type Am*Bn* … Rp*Xq* … are discussed in terms of effective LARMOR-frequencies. Explicit experimental conditions for which observed spectra are apparently simple are given for spectra of the type An*BXq* as well as A2B2X.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19640470102
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Substituenteneffekte in kernmagnetischen Protonenresonanzspektren von substituierten Benzolen (1961)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 44 (1961), S. 829-843 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substitution effects in proton magnetic resonance spectra of meta- and paradisubstituted benzene are shown to be additive at low concentration in hexane. The absolute values of the effects are measured in meta-disubstituted benzene. Substitution effects in paradisubstituted benzene are separated by substitution of the values thus obtained and are used to predict chemical shifts. In orthodisubstituted and in polysubstituted benzene as well as in paradisubstituted benzene with mesomeric interaction new substitution effects are found and discussed. Correlations of substitution effects with Hammett-parameters are given. An electrostatic theory of substitution effects is shown to be a good approximation as long as the resonance contribution to the shifts is low.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19610440327
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Chemische Verschiebungen in der kernmagnetischen Resonanz von 17O in organischen Verbindungen (1961)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 44 (1961), S. 865-880 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements of 17O-NMR-chemical shifts (relative to H2O) have been carried out in a variety of 125 compounds of which 115 are organic.1The resonance of singly bonded oxygen is shifted to low field by all substituents except CH3. The effects of atoms directly bonded to oxygen increases in the order H, C, S, Cl 〈 N 〈 O. Double bonds —O—C=X (X = C, 0) give rise to considerable shifts, whereas groups bonded to C affect the resonance only slightly.2In carbonyl groups the resonance of doubly bonded oxygen is shifted to high field (relative to acetaldehyde) by all substituents. The effect of heteroatoms bonded to C decreases in the order N 〉 O 〉 F 〉 Cl 〉 Br. Conjugation does not affect the shifts. The chemical shifts of the carbonyl group are sensitive to solvents.3An isotope effect on the chemical shift has been detected in water (H317O/D217O).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19610440331
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Deuteronen-Kernresonanzspektroskopie (1964)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 47 (1964), S. 545-557 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to be detectable, the volume concentration of chemically equivalent deuterons has to exceed a certain minimum limit. As this volume concentration decreases with increasing molecular volume, deuteron NMR. at natural abundance is limited to small molecules and therefore of no practical importance. (At a density of 1 the molecular weight has to be less than 20 per chemically equivalent deuteron.)In fully deuterated samples the signal-to-noise ratio is of the same order of magnitude as for protons, because the loss in sensitivity can be compensated by an increased volume of the sample.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19640470221
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Chemische Verschiebungen in Kernresonanzspektren von substituierten Mesitylenen und Durolen (1963)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 46 (1963), S. 461-467 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of substituents on ring protons as well as on methylgroups in mesitylenes and durenes are compared with substitution effects in benzene.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19630460206
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Lösungsmitteleffekte in kernmagnetischen Protonenresonanzspektren von substituierten Benzolen (1962)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 45 (1962), S. 568-580 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solvent effects of acetone and benzene in the proton resonance spectra of substituted benzene molecules can be divided into contributions from the individual substituents. These additive contributions are measured. There are departures from additivity in ortho-disubstituted benzene. The solvent effects thus measured can be used to predict solvent effects in mono- and polysubstituted benzene as long as there is negligible interaction between the substituents.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19620450220
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    Paper (German National Licenses)
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