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  • 1985-1989  (3)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Acid deuterium exchange in benzazoles (1986)
    Springer
    Chemistry of heterocyclic compounds 22 (1986), S. 557-564 
    Details
    ISSN: 1573-8353
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of acid deuterium exchange in benzazoles carrying electron-donor substituents in the 5-, 6-, or 7-positions have been studied. Mass spectrometric studies have shown that exchange in 5-methoxy-1, 2-dimethylbenzimidazole takes place exclusively at one position in the benzene ring, in 5-chloro-, 7-chloro-,5-methoxy-2-methylbenzothiazole and 6-methoxy-2-methylbenzoxazole simultaneously in two positions, and in 6-methoxy-2-methylbenzothiazole the hydrogen at all three possible positions is exchangeable. Using quantum chemical reactivity indices (CNDO/2) in dynamic and state approximations, the orientational features of the reaction have been ascertained. The lack of agreement between the reactivities of the most reactive sites to exchange in heteroaromatic bicycles of similar structure and electrophilic localization energies is explained by differences in the energy profile of the reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00519540
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  • 2
    Electronic Resource
    Electronic Resource
    Intensities of IR bands of CH stretching vibrations and atomic charges in saturated three-membered rings (1989)
    Springer
    Chemistry of heterocyclic compounds 25 (1989), S. 1342-1348 
    Details
    ISSN: 1573-8353
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The intensities of the absorption bands of the CH stretching vibrations in the IR spectra of solutions of cyclopropane, aziridine, oxirane, and thiirane in CCl4 were measured. Quantum-mechanical calculations of these intensities were performed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00473861
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  • 3
    Electronic Resource
    Electronic Resource
    Acid deuterium exchange in methoxyquinolines and their N-oxides (1986)
    Springer
    Chemistry of heterocyclic compounds 22 (1986), S. 522-529 
    Details
    ISSN: 1573-8353
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Kinetic studies of acid deuterium exchange have been carried out for a series of isomeric 6-, 7-, and 8-methoxyquinolines and their N-oxides, in comparison with the analogous carbocyclic compounds. It has been found that methoxyquinolines are deuterated in the N-protonated form, whereas the N-oxides are reactive in their neutral forms. In full agreement with data for the reactivity of these heterocycles in nitration, quantum chemical calculations show that in exchange in 6-methoxyquinoline and its N-oxide the preferred site for electrophilic attack is the 5-position, and in the 7-isomers the 8-position is preferred. The rate is lower in the 8-isomer, owing to the presence in the latter of intramolecular hydrogen bonding. The probable structure of the transition state in the reaction is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00519532
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