Theoretical studies on the gas-phase pyrolysis of 2-phenoxycarboxylic acids : an ONIOM approach
Copyright 2003 Wiley Periodicals, Inc. J Comput Chem 24: 963-972, 2003
| Veröffentlicht in: | Journal of computational chemistry. - 1984. - 24(2003), 8 vom: 30. Juni, Seite 963-72 |
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| 1. Verfasser: | |
| Weitere Verfasser: | , , |
| Format: | Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2003
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| Zugriff auf das übergeordnete Werk: | Journal of computational chemistry |
| Schlagworte: | Journal Article |
| Zusammenfassung: | Copyright 2003 Wiley Periodicals, Inc. J Comput Chem 24: 963-972, 2003 Various ONIOM combinations-ONIOM(HF/6-31G*: PM3), ONIOM(B3LYP/6-31G*: PM3), ONIOM(MP2/6-31G*: PM3), and ONIOM(MP2/6-31G*: HF/3-21G)--were applied to investigate thermal decomposition mechanisms of four 2-phenoxycarboxylic acids (2-phenoxyacetic acid, 2-phenoxypropionic acid, 2-phenoxybutyric acid, and 2-phenoxyisobutyric acid) in the gas phase. All the transition states and intermediates of the reaction paths were optimized. The reaction pathway of four reactants yielding the phenol, CO, and the corresponding carbonyl compound was characterized on the potential energy surface and found to proceed stepwise. The first step corresponds to the elimination of phenol and the formation of alpha-lactone intermediate through a five-membered ring transition state, and the second step is the cycloreversion process of alpha-lactone intermediate to form CO and the corresponding carbonyl compound. The reaction pathway of latter three compounds to produce the carboxylic acid and phenol via a four-membered cyclic transition structure was also examined theoretically. Comparison with experiment indicates that the activation parameters for the fist reaction channel are accurately predicted at the ONIOM(MP2/6-31G*: HF/3-21G) level of theory |
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| Beschreibung: | Date Completed 09.12.2003 Date Revised 29.04.2003 published: Print Citation Status PubMed-not-MEDLINE |
| ISSN: | 0192-8651 |