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  • Analytical Chemistry and Spectroscopy  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Spectroscopic characterization of some chlorinated tricyclic hydrocarbons of the C10 series: Chlordanes, chlordenes and nonachlors (1977)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 9 (1977), S. 536-542 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon-13 and proton nuclear magnetic resonance (n.m.r.) spectra of ten chlorinated hydrocarbons, which are components of technical chlordane and one chlordane metabolite, were examined. For chlordene, dichlorochlordene, cis- and trans-nonachlor, and cis- and trans-chlordane, whose chemical structures are well-established, the relationships between the n.m.r. parameters and these structures were investigated. The results allow confirmation of proposed structures for α-, β-, and γ-chlordene. A structure, corresponding to 2,4,5,5,6,7,8,8-octachloro-2,3,3a,4,5,7a-hexahydro-1,4-methano-1-H-indene, is proposed for another chlordane component, previously known only as Compound K.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270090910
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  • 2
    Electronic Resource
    Electronic Resource
    13C n.m.r. studies of some phenanthrene and fluorene derivativesPart 67 in the series 13C n.m.r. Studies. For Part 66 see Ref. 25. (1977)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 9 (1977), S. 408-413 
    Details
    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 spectra of fluorene, fluorenone, phenanthrene and their 4-methyl and 4,5-dimethyl derivatives have been examined. To complete the analyses for fluorenone and 4-methylfluorenone, 1H spectra were recorded at 270 MHz. The results from the 1H spectra permitted unequivocal assignments for the protonated aryl carbons by selective proton decoupling. A consistent set of assignments for the quaternary carbons was obtained through consideration of the dominant relaxation processes operative at these centres. This series of compounds was examined to investigate the shielding effects produced by the close approach of methyl groups separated by five bonds for comparison with the contrasting trends found for methyl carbons separated by three and four bonds. The results indicate that the relative orientation of the methyl groups is an extremely critical factor governing their shieldings and those of neighboring centres.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270090708
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  • 3
    Electronic Resource
    Electronic Resource
    Intramolecular motion and reorientational barriers in 9-fluorenone, 4-methyl-9-fluorenone and 4,5-dimethyl-9-fluorenonePresented in part at the 186th National Meeting of the American Chemical Society, Washington, DC, August 28-Septmber 2, 1983. Abstract ORGN 144. This paper has not been subjected to Agency review and does not necessarily reflect the views of the agency. (1985)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 23 (1985), S. 12-15 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon-13 nuclear magnetic resonance spin-lattice relaxation times and nuclear Overhauser enhancements were measured as functions of temperature for the hydrogen-bearing carbons in 9-fluorenone, 4-methyl-9-fluorenone and 4,5-dimethyl-9-fluorenone. Reorientational diffusion constants were obtained from the dipolar T1 values. Isotropic overall molecular motion was assumed, and the methyl group rotation was separated from the overall molecular reorientation by the method of Woessner. Arrhenius plots of the dependence of the rotation rates on temperature provided values of the energy barriers for molecular reorientation and methyl group rotation. The energy barriers for molecular reorientation are essentially the same: 9-fluorenone 11.8 ± 0.5 kJ mol-1, 4-methyl-9-fluorenone 11.9 ± 0.5 kJ mol-1 and 4,5-dimethyl-9-fluorenone 11.7 ± 0.2 kJ mol-1. The barriers to methyl group rotation are 4-methyl-9-fluorenone 7.8 ± 0.9 kJ mol-1 and 4,5-dimethyl-9-fluorenone 11.0 ± 0.5 kJ mol-1. Thus the bay methyl-methyl steric interaction in 4,5-dimethyl-9-fluorenone increases the methyl rotational barrier by 3.2 kJ mol-1.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260230106
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