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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 4 (1991), S. 721-725 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The x-ray structure of methyl 5-nitro-2-methylbenzoate was determined [M,r = 195.17, monoclinic, P,21/c, a, = 7.265(1), b, = 7.749(1), c, = 16.526(3) Å, α; = 91.50(2)., V, = 930.0(3) Å3, Z, = 4, D,x = 1.39 g cm-3, Cu Kα, Λ = 1.5418 Å, μ = 9.56 cm-1, F,(000) = 408, T, = 291 K, R, = 0.081 for 1295 observed reflections]. In contrast to the planar molecule of the corresponding acid, studied previously, the carboxylate group in the ester molecule is twisted through an angle 25° from the ring plane. This torsion angle was estimated to be 65° in benzene solution; the estimation was based on the dipole moment and that of methyl 2-methylbenzoate. For the corresponding ethyl esters a value of 79° was found in a similar way. Although these results are expressed in terms of one non-planar conformation, the alternative explanation of an equilibrium of two planar forms is not excluded in solution. The only safe conclusion is that the energy differences are small and the conformation is sensitive both to the conditions and to small changes in structure; a large part of the observed effects of an ortho,-methyl group are due to reasons other than to the hindered resonance.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 476-483 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dipole moments of para-substituted benzoyl chlorides and bromides, partly measured in benzene and partly recalculated from elderly literature, were analysed in terms of bond moments and additional contributions expressing the conjugation. Although the gross moments are similar, their decomposition yields different pictures for acyl chlorides and bromides. Only in the latter can significant electron transfer from the halogen be observed. On the other hand, conjugation with the benzene nucleus is strong in both aromatic acyl chlorides and bromides, but stronger in chlorides. There is agreement with the evidence from some other physical quantities but not from all.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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