Taft equation in the light of NBO computations introduction of a novel polar computational substituent constant scale sigma(q)* for alkyl groups
- The validity of the Taft equation: log(k(R)/k(CH3)) = rho*sigma* + delta E-S was studied with the aid of NBO computational results concerning cyclohexyl esters RCOOC6H11 [R = Methyl, Ethyl, n-Propyl, Isopropyl, n-Butyl, Isobutyl, sec-Butyl, tert-Butyl, Neopentyl, CH(CH2CH3)(2), CH(CH3)C(CH3)(3), C(CH3)(2)CH2CH3, C(CH3)(2)C(CH3)(3), CH(CH3)(Np), CH(iPr)(tBu), C(Me)(Et)(iPr), C(Et)(2)(tBu) or C(Et)(iPr)(tBu)]. It was proved that the sigma*(alkyl) value is a composite substitutent constant including the polar and steric contributions. A novel computational sigma(q)* substituent constant scale is presented based on the NBO atomic charges of the alpha-carbon and the computational total steric exchange energies E(ster) of the cyclohexyl esters specified above. The method used offers a useful way to calculate sigma*(alkyl) values for alkyl groups for which experimental Taft's polar sigma* parameters are not available.
Verfasserangaben: | Kari Neuvonen, Helmi Neuvonen, Andreas KochORCiDGND, Erich KleinpeterORCiDGND |
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DOI: | https://doi.org/10.1016/j.comptc.2011.11.044 |
ISSN: | 2210-271X |
Titel des übergeordneten Werks (Englisch): | Computational and theoretical chemistry |
Verlag: | Elsevier |
Verlagsort: | Amsterdam |
Publikationstyp: | Wissenschaftlicher Artikel |
Sprache: | Englisch |
Jahr der Erstveröffentlichung: | 2012 |
Erscheinungsjahr: | 2012 |
Datum der Freischaltung: | 26.03.2017 |
Freies Schlagwort / Tag: | NBO analysis; Polar substituent constant; Steric effect; Taft equation |
Band: | 981 |
Ausgabe: | 2 |
Seitenanzahl: | 7 |
Erste Seite: | 52 |
Letzte Seite: | 58 |
Organisationseinheiten: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie |
Peer Review: | Referiert |