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  • Chemistry  (8)
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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of the 19F and 1H NMR spectra of a number of polyfluoroindenes (1980)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 14 (1980), S. 258-263 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 19F and 1H NMR spectra of the products of nucleophilic attack on octafluoroindene are analysed and structures assigned. The major product in the reaction of butyllithium with octafluoroindene is 3-methylheptafluoroindene, with sodium borohydride it is 2-hydroheptafluoroindene and with sodium methoxide it is 3-methoxyheptafluoroindene. Vacuum pyrolysis of undecafluorotricyclo[5.2.2.02,6]undeca- 2,5,8-triene, with elimination of C2F4, gives 6-hydroheptafluoroindene as the major product. The NMR assignments are based on the unambiguous synthesis via vacuum pyrolysis of 5,6-dihydrohexafluoroindene, 3-hydro- and 3-methyl-heptafluoroindene and the large long-range coupling of 15 Hz assigned to the F-2, F-6 interaction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270140408
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  • 2
    Electronic Resource
    Electronic Resource
    19F NMR of five polyfluoronaphthalenes. Inter-ring FF coupling constants (1982)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 18 (1982), S. 226-230 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analyses of the 19F and 1H spectra of 1,2,3,4,5-pentafluoro-, 1-bromo-4,5,6,7,8-pentafluoro-, 1,2,3,4,5,6-hexafluoro-, and 1-bromo-3,4,5,6,7,8-hexafluoro-naphthalene are presented, and it is observed that the Fermi contact mechanism does not, simply, account for the long range couplings. Calculations of the carbon-carbon polarizability part of the Fermi contact term do, however, imply that inter-ring F,F couplings should be almost constant from difluoro- to heptafluoro-naphthalene. Within the limits of this study, the inter-ring F,F couplings, excluding peri F,F couplings, do not vary substantially. The steric effect of substituting an α-hydrogen with bromine, at a peri position and adjacent to fluorine, is to increase the F,F coupling at the opposed peri position by 20 Hz, an unusually high increase in J(FF)peri.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270180412
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  • 3
    Electronic Resource
    Electronic Resource
    19F n.m.r spectra of heptafluoroisoquinoline and hexafluoro-1-methoxyisoquinoline. Long-range inter-ring coupling constants (1976)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 8 (1976), S. 628-631 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analysis of the 19F n.m.r. spectra of heptafluoroisoquinoline and hexafluoro-1-methoxyisoquinoline is presented. As in heptafluoroquinoline, the inter-ring F—F coupling constants alternate in sign and magnitude and are positive over an odd number of bonds. They correlate with SCFMO carbon-carbon polarizabilities and this infers that the long-range coupling mechanism is dominated by the contribution from the π-electron system.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270081208
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  • 4
    Electronic Resource
    Electronic Resource
    G. A. Webb (editor). Annual reports on NMR spectroscopy, volume 10B. Fluorine-19 nuclear magnetic resonance by V. Wray. Academic Press, London 1980. pp. 511, £38.50 (1982)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 18 (1982), S. iii 
    Details
    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
    URL: http://dx.doi.org/10.1002/mrc.1270180417
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  • 5
    Electronic Resource
    Electronic Resource
    19F n.m.r spectra of polyfluoroquinolines. Long range inter-ring 19F—19F coupling constants and 19F chemical shifts (1976)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 8 (1976), S. 240-245 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The signs and magnitudes of every fluorine-fluorine coupling constant in perfluoroquinoline (1), 2,4-dichloropentafluoroquinoline (2) and 2-bromohexafluoroquinoline (3) have been determined by 19F n.m.r. These provide an unambiguous assignment of the spectrum of the first compound and its derivatives. Inter-ring fluorine-fluorine coupling constants were found to be positive over an odd number of bonds and negative over an even number of bonds, similar to that observed in proton-proton coupling constants in multicyclic systems.The 19F chemical shifts of perfluoroquinoline and its protonated salt are reported and directly correlated with SCF MO calculated π-electron densities at both fluorine and bonded carbon atoms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270080505
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  • 6
    Electronic Resource
    Electronic Resource
    19F n.m.r. spectrum of hexafluoroquinazoline long-range inter-ring F—F coupling constants (1977)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 9 (1977), S. 318-321 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 19F n.m.r. spectrum of hexafluoroquinazoline has been analyzed giving the signs and magnitudes of all but two of the coupling constants, and supporting the analyses of the 19F n.m.r. spectra of heptafluoroquinoline and heptafluoroisoquinoline. Long range F—F inter-ring coupling constants are a guide for assessing π-electron delocalization pathways. In addition, nitrogen in the β position enhances the distant F-5, F-7 meta-coupling constant, implying a π-contribution to J(FF)meta. A rationalization of changes in peri-coupling constants is also presented. The observed changes appear to be the sum of two effects: (i) ring contraction by the insertion of shorter C—N bonds into the aromatic ring and (ii) a secondary effect which is dependent on the existence of a β-nitrogen, adjacent to the peri nuclei.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270090606
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  • 7
    Electronic Resource
    Electronic Resource
    13C NMR spectra of some halocarbons. Shift predictions in polychloro-quinolines and -isoquinolines (1989)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 27 (1989), S. 841-845 
    Details
    ISSN: 0749-1581
    Keywords: Polychloroazanaphthalenes ; Multiple substituent chemical shifts ; MSCS ; NIMS ; 13C predictions ; Molecular orbital charge calculations ; CNDO/2 calculations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three methods, two empirical and one semi-empirical, for predicting 13C chemical shifts in six poly-chloroheterocyclics are considered. It was found that the semi-empirical correlations with CNDO/2 calculated charges, although useful, could not be used in isolation from the other two methods. Of these, the MSCS (multiple substituent chemical shifts) method could be used to predict all eighteen carbon shifts in perchloroquinoline and perchloroisoquinoline, whilst the NIMS method (hypothetical nitrogen insertion method) was limited to the carbons in the heterocyclic ring. In brief, it was found that the MSCS method was the most accurate (less than ± 1 ppm) for predicting chemical shifts, intrinsically compensating for some of the errors arising from mutual atom-atom interactions.New 13C data are reported for heptachloroquinoline, a mixture of two polychloroquinolines, hepta-chloroisoquinoline and two, separable, new polychloroisoquinolines.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260270906
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  • 8
    Electronic Resource
    Electronic Resource
    15N INEPT spectra of some perfluoroazines (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 547-548 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Natural abundance 15N NMR spectra were measured for pentafluoropyridine and five other perfluorodiazines. The spectra were obtained using the INEPT pulse sequence with 19F as the source of polarization. The nitrogen nuclei are shielded by approximately 56-97 ppm with respect to the hydrocarbon analogues, and the 2J(NF) values appear to be approximately 52 Hz.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260240613
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