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  • 1
    Electronic Resource
    Electronic Resource
    Conversion of flavanones into chalcones in alkaline medium. Kinetic and spectroscopic studies (1991)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 4 (1991), S. 263-270 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conversion of flavanone and 7-hydroxyflavanone in alkaline water and heavy water and of the same compounds and of 4′ -nitroflavanone in alkali-methanolic media into the corresponding substituted chalcones was studied kinetically and spectroscopically. Treatment of kinetic data in this work and data for the reverse reaction determined previously allowed the estimation of the partial rate coefficients for each step and of the free-energy changes for the three systems studied. To disentangle isotope effects, the conversion of [3-D2]-flavanone was also studied. The present results confirm a previously suggested mechanism for the spontaneous reaction and afford essential information that may contribute to a more detailed understanding of the mechanism of the enzyme-catalysed reaction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610040502
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  • 2
    Electronic Resource
    Electronic Resource
    REACTIONS OF LITHIUM WITH BENZALDEHYDE IN SOLUTION (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 233-241 
    Details
    ISSN: 0894-3230
    Keywords: surface effects ; radical anions ; benzoyl radical ; coupling of radicals ; surface catalysis ; electron transfer ; reactions in the double laye ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Benzaldehyde in THF reacts with lithium metal to give the expected reduction product, benzyl alcohol, plus benzoin and benzyl as minor products. The kinetics of the overall reaction as well as the partial rate coefficients of the several steps have been determined under various reaction conditions. It was found that adsorption on the surface and electron transfer from the lithium to benzaldehyde are the slow steps. The experimental results show interesting surface effects, and evidence for significant radical intermediates, which were characterized by their epr spectra and trapping experiments, results useful to gain insight into the mechanisms of these and other related reactions. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    1H and 13C NMR studies of substituted nitropyridines and nitrobenzenes (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 507-511 
    Details
    ISSN: 0749-1581
    Keywords: Nitropyridines ; Nitrobenzenes ; 1H and 13C NMR ; Hydrogen bonding ; Conformation MS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H and 13C NMR spectra of 3-nitro-, 5-nitro- and 3,5-dinitro-2-methoxypyridines have been determined. The results show the preferred cis conformation for the 2-methoxy group, and the importance of steric repulsion between the oxygen atom of this group and those of the o-nitro group which hinders conjugation in the 3-nitro-substituted derivatives. Similar steric inhibition of resonance is observable with 2-N-butylamine-, 2-N-cyclohexylamine- and 2-(N-piperidyl)-substituted nitropyridines, whose 1H and 13C NMR spectra were also determined. In the case of the secondary amines, a hydrogen bond between the amino proton and the 3-nitro group was clearly detected. 1H and 13C NMR spectra of 2,6-dinitro-, 2,4-dinitro- and 2,4,6-trinitro-2-R-benzenes (R = OCH3, NHC4H9, NH-cyclo-C6H11, NC5H10) were also recorded and compared with those of the pyridine derivatives. The electronic aza and nitro group effects are comparable if conjugation of the nitro group is not hindered.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260240607
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  • 4
    Electronic Resource
    Electronic Resource
    13C NMR studies on radical anions. Special solvent effects (1990)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 576-579 
    Details
    ISSN: 0749-1581
    Keywords: Radical anions ; Benzophenone ketyl ; Aryllithiums ; Electron transfer ; Spin density transfer ; Ternary ‘inner sphere’ complex ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of radical ions is crucial in mechanistic studies of reactions in which single electron transfer is suspected. A 13C NMR method based on the interaction of radical anions with tetrahydrofuran (THF) molecules is presented; measurements of the broadening of the THF α-carbon signal allow determination of the substrate concentration in the range 0.2-1.2 M. The spectacular effect observed on addition of small amounts of benzene greatly improved the method. In addition, studies of the spin-lattice, T1, and of the transverse nuclear, T2, relaxation times and of the effects of added co-solvents allow the proposal of the bonding situation and of the degree of coordination in the radical anion-cation-THF molecules' complex.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260280704
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