| Influence of fluorine atoms and aromatic rings on the acidity of ethanol. | |
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MedLine Citation:
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PMID: 19751060 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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Absolute gas-phase acidities Delta(acid)G(0)(OH) and Delta(acid)G(0)(CH) were calculated at the B3LYP and MP2 levels using six different standard basis sets for the OH and CH heterolytic bond cleavage of ethanol and twelve derivatives of the type CH(3-n)F(n)CHX(r)OH, where n ranges from zero to three and represents the number of fluorine atoms and r represents hydrogen and the type of aromatic ring, namely: X(0) = hydrogen, X(1) = phenyl, X(2) = 1-naphthyl, and X(3) = 9-anthryl. The similarity between calculated and experimental Delta(acid)G(0)(OH) values for ethanol (1a), 2-fluoroethanol (1b), 2,2-difluoroethanol (1c), 2,2,2-trifluoroethanol (1d), and 1-phenylethanol (2a) was used to validate the right theoretical method for this study. Substituent partial contributions to hydroxyl-, methylene-, and methine-hydrogen acidities were evaluated by linear combination. Good parameter fittings of the primary and secondary alcohols were obtained and interpreted as additive contribution of the substituent effects. The nonlinear contributions were identified. Calculations prove that fluoroalcohols exhibit C-H acidity, which is usually lower than O-H acidity. In principle, the inversion of this acidity order is possible by the introduction of a large aromatic ring instead to increase the number of fluorine atoms. |
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Authors:
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Ramsés E Ramírez; Cirilo García-Martínez; Francisco Méndez |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The journal of physical chemistry. A Volume: 113 ISSN: 1520-5215 ISO Abbreviation: J Phys Chem A Publication Date: 2009 Oct |
Date Detail:
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Created Date: 2009-10-01 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9890903 Medline TA: J Phys Chem A Country: United States |
Other Details:
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Languages: eng Pagination: 10753-8 Citation Subset: - |
Affiliation:
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Departamento de Química, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, A.P. 55-534, México, D.F., 09340 México. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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