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  • 1990-1994  (1)
  • 1965-1969  (1)
  • Chemistry  (2)
  • Molecular structure  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Structure determination of a new saponin from the plant Alphitonia zizyphoides by NMR spectroscopy (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 472-480 
    Details
    ISSN: 0749-1581
    Keywords: Alphitonia zizyphoides ; Saponin ; 2D NMR ; INADEQUATE ; Molecular structure ; Computerized spectral analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-field NMR experiments, including the 2D INADEQUATE technique coupled with a computerized spectral analysis, were used to determine the full structure of a new saponin extracted from a plant (Alphitonia zizyphoides) found in the Samoan rain forests. The saponin, which shows significant pharmacological activity, consists of an aglycone framework of six rings (three saturated six-membered rings, two oxygen-containing five-membered rings and a five-membered carbon ring) to which are attached four sugar units and a six-carbon side-chain. The INADEQUATE experiment, which was carried out on 60 mg of sample, provided absolute confirmation of the assignments for 35 of the possible 53 C—C bonds from the 13C-13C connectivities.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260310511
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Structural study of phenol-formaldehyde polymers with proton magnetic resonancePresented in part at the Conference on Analytical Chemistry and Applied Spectroscopy in Pittsburgh, Pa., March, 1962. (1965)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 3 (1965), S. 2091-2105 
    Details
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Proton magnetic resonance spectra were obtained for a number of representative phenol-formaldehyde dimers and trimers of known structure and for related compounds having methyl or chloro substituents on the aromatic ring. The data thus obtained, particularly for the methylene protons, were used in the interpretation of the structure of well characterized, linear phenol-formaldehyde polymers and the corresponding halogenated polymers prepared by the condensation of o- and p-chlorophenol with formaldehyde. In all cases there was a shift to lower field as the methylene linkage was varied from para-para to ortho-para to ortho-ortho, although in certain instances the ortho-para and ortho-ortho peaks moved very close together. The spectra obtained indicated that the condensation of o-chlorophenol with formaldehyde proceeds in an essentially random manner, since the ratio of ortho-ortho to ortho-para to para-para methylene linkages was found to be 1:2:1, within the limits of experimental error. The preliminary results obtained in this work clearly demonstrate the potential utility of PMR as a valuable tool in the characterization of the highly complex products obtained from phenol-formaldehyde systems.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1965.100030602
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    Paper (German National Licenses)
    Fulltext
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