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  • 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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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of hydrogen bonding ability of liquids and solids by C-13 NMR. Silica gel as a strong hydrogen bond donor (1995)
    Springer
    Catalysis letters 31 (1995), S. 351-358 
    Details
    ISSN: 1572-879X
    Keywords: hydrogen bonding, measurement by NMR ; NMR, hydrogen bonding evaluation by ; solids, hydrogen bonding ability of ; solvents, hydrogen bonding ability of ; supports, hydrogen bonding ability of
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The chemical shift difference between signals of C(β) and C(α) of unsaturated ketones, Δδ, which we used before to measure acid strengths, has now been used to evaluate the hydrogen bond donor ability of solvents which are not acidic enough to hydronate the indicator. For such solvents there is no general correlation between H-bond donor ability and acid strength: hexa-fluoroisopropanol is a much weaker acid than acetic acid, but it is a stronger H-bond donor. The method can be applied to evaluate the H-bonding properties of solid surfaces, and it was thus found that silica gel has a much stronger H-bond donor ability than methanol or acetic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00808599
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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