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  • H‐bond donor strength and acid strength  (1)
  • Keywords Hydronium tetrafluoroborate, Ion pairs, Ion clusters, Ab initio calculations, GIAO-B3LYP chemical shift calculations  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Absence of correlation of hydrogen bond donor ability with acid strength and catalytic activity of acid catalysts (1998)
    Springer
    Catalysis letters 53 (1998), S. 3-6 
    Details
    ISSN: 1572-879X
    Keywords: acid strength and catalytic activity ; acid strength and H‐bond donor strength ; catalytic activity and acid strength ; catalytic activity and H‐bond donor strength ; H‐bond donor strength and acid strength ; H‐bond donor strength and catalytic activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two liquids, acetic acid and hexafluoroisopropanol (HFIP), and two solids, silica gel and polymethacrylic acid (PMA), were compared for hydrogen bond donor ability, acid strength, and catalytic activity in typical acid‐catalyzed reactions, inversion of sugar and cleavage of acetone dimethyl ketal. In each pair, the weaker acid (HFIP and silica gel, respectively) was much the stronger hydrogen bond donor, but was totally devoid of catalytic activity, which the poor hydrogen bond donor but stronger acids (acetic and methacrylic acid, respectively) exhibited. A strong hydrogen bond donor (e.g., HFIP) enhances, however, the catalytic activity of the acid catalyst (AcOH). Thus, hydrogen bond donor ability is not a measure of acid strength. A correlation of the two properties is possible only when each group (acids and bases) involved in the comparison consists of very close structural relatives. Such a correlation cannot be extrapolated to any other case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019068814279
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  • 2
    Electronic Resource
    Electronic Resource
    The Hydronium Tetrafluoroborate Dimer in Nonpolar Media and its Proton NMR Spectrum (2000)
    Springer
    Journal of molecular modeling 6 (2000), S. 171-176 
    Details
    ISSN: 0948-5023
    Keywords: Keywords Hydronium tetrafluoroborate, Ion pairs, Ion clusters, Ab initio calculations, GIAO-B3LYP chemical shift calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hydronium tetrafluoroborate ion pairs, H3O+·BF4 - have been shown computationally to be unstable toward decomposition, in the absence of solvation or electrostatic interactions existing in crystals. As the proton NMR spectrum of a hydronium salt with the octanesulfonate-antimony pentachloride complex anion was reported in freon solution, we investigated the hypothesis that larger ionic clusters were present in the nonpolar solvent. It was found that the dimer (H3O+·BF4 -)2 was stable at the MP2/6-31G* level. GIAO-B3LYP chemical shift calculations with the same basis set and also with the 6-31G**, 6-31++G**, 6-311++G**, dzvp, tzp, tz2p, and qz2p basis sets conducted on the hydronium fluoroborate dimer reproduce the main features of the experimental spectrum: the existence of two signals with a two-to-one intensity ratio and the more intense resonance at higher frequency (more deshielded). The alternative structures, of hydronium tetrafluoroborate ion pairs with one and with two hydrogen bonds between anion and cation, give calculated chemical shifts which are farther from the experimental values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010726
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    Paper (German National Licenses)
    Fulltext
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