| Thermodynamic study of sesamol, piperonyl alcohol, piperonylic acid and homopiperonylic acid: a combined experimental and theoretical investigation. | |
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MedLine Citation:
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PMID: 15007421 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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The standard (p(o)= 0.1 MPa) molar energies of combustion in oxygen, at T= 298.15 K, of four 1,3-benzodioxole derivatives (sesamol, piperonyl alcohol, piperonylic acid and homopiperonylic acid) were measured by static bomb calorimetry. The values of the standard molar enthalpies of sublimation, at T= 298.15 K, were derived from vapour pressure-temperature measurements using the Knudsen effusion technique. Combining these results the standard molar enthalpies of formation of the compounds, in the gas phase, at T= 298.15 K, have been calculated: sesamol (-325.7 +/- 1.9) kJ mol(-1); piperonyl alcohol (-329.0 +/- 2.0) kJ mol(-1); piperonylic acid (-528.9 +/- 2.6) kJ mol(-1) and homopiperonylic acid (-544.5 +/- 2.9) kJ mol(-1). The most stable geometries of all the compounds were obtained using the density functional theory with the B3LYP functional and two basis sets: 6-31G** and 6-311G**. The nonplanarity of the molecules was analyzed in terms of the anomeric effect, which is believed to arise from the interaction between a nonbonded oxygen p orbital and the empty orbital sigma*(CO) involving the other oxygen atom. Calculations were performed to obtain estimates of the enthalpies of formation of all the benzodioxoles using appropriate isodesmic reactions. There is a perfect agreement between theoretical and experimental results. |
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Authors:
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M Agostinha R Matos; Manuel J S Monte; Clara C S Sousa; Ana R R P Almeida; Victor M F Morais |
Publication Detail:
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Type: Journal Article Date: 2004-02-23 |
Journal Detail:
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Title: Organic & biomolecular chemistry Volume: 2 ISSN: 1477-0520 ISO Abbreviation: Org. Biomol. Chem. Publication Date: 2004 Mar |
Date Detail:
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Created Date: 2004-03-09 Completed Date: 2005-08-05 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101154995 Medline TA: Org Biomol Chem Country: England |
Other Details:
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Languages: eng Pagination: 908-14 Citation Subset: - |
Affiliation:
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Centro de Investigação em Química, Departamento de Química, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto, Portugal. marmatos@fc.up.pt |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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