Calculated bond dissociation energies and enthalpy of formation of α-amino acid radicals
| Autor: | Peter L. Warburton, Kabir M. Uddin, Raymond A. Poirier, David J. Henry |
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| Rok vydání: | 2016 |
| Předmět: |
Isodesmic reaction
010405 organic chemistry Chemistry Radical 010402 general chemistry 01 natural sciences Captodative effect Bond-dissociation energy Standard enthalpy of formation 0104 chemical sciences Homolysis Computational chemistry Intramolecular force Side chain Physical chemistry Physical and Theoretical Chemistry |
| Zdroj: | Theoretical Chemistry Accounts. 135 |
| ISSN: | 1432-2234 1432-881X |
| DOI: | 10.1007/s00214-016-1975-9 |
| Popis: | Bond dissociation energies (BDEs), radical stabilization energies (RSEs) and the enthalpies of formation (Δf H°( $${\text{AA}}^{\bullet}$$ )) for the Cα-centered radical of 20 common α-amino acids were calculated at the G3MP2 level of theory. In addition, BDEs and Δf H°( $${\text{AA}}^{\bullet}$$ ) for the Cα-centered radicals were calculated via atomization, homolytic, isogyric and isodesmic reactions using 31 reference compounds. RSEs for the α-amino acid radicals reveal a strong captodative effect due to the resonance stabilization. Intramolecular H-bonding and steric repulsion between the side chains and –NH2 and ‒COOH also have an effect on the stability of α-carbon-centered radicals. For the key small reference compounds investigated, the BDEs (Δf H°( $${\text{AA}}^{\bullet}$$ )) computed with isodesmic reactions were found to be quite consistent with each other in terms of mean absolute deviations (MADs) and root-mean-square deviations between 2.0 (2.6) and 3.2 (4.4) kJ mol−1 from experimental data. |
| Databáze: | OpenAIRE |
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