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dc.contributor.authorMoreira, José A.
dc.contributor.authorCosta, Ana M. Rosa da
dc.contributor.authorGarcía Río, Luis
dc.contributor.authorPessêgo, Márcia Isabel Duarte
dc.date.accessioned2020-05-20T08:12:27Z
dc.date.available2020-05-20T08:12:27Z
dc.date.issued2011
dc.identifier.citationMoreira, J. A.; Rosa da Costa, A. M.; García-Río, L.; Pessêgo, M. Beilstein J. Org. Chem. 2011, 7, 1732–1738. doi:10.3762/bjoc.7.203
dc.identifier.issn1860-5397
dc.identifier.urihttp://hdl.handle.net/10347/22450
dc.description.abstractThe protonation equilibria of four substituted N-methylbenzenesulfonamides, X-MBS: X = 4-MeO (3a), 4-Me (3b), 4-Cl (3c) and 4-NO2 (3d), in aqueous sulfuric acid were studied at 25 °C by UV–vis spectroscopy. As expected, the values for the acidity constants are highly dependent on the electron-donor character of the substituent (the pKBH+ values are −3.5 ± 0.2, −4.2 ± 0.2, −5.2 ± 0.3 and −6.0 ± 0.3 for 3a, 3b, 3c and 3d, respectively). The solvation parameter m* is always higher than 0.5 and points to a decrease in the importance of solvation on the cation stabilization as the electron-donor character of the substituent increases. Hammett plots of the equilibrium constants showed a better correlation with the σ+ substituent parameter than with σ, which indicates that the initial protonation site is the oxygen atom of the sulfonyl group
dc.description.sponsorshipThis work was funded by Fundação para a Ciência e Tecnologia – Portugal (POCI/QUI/57077/2004) and CIQA, Centre for Research in Chemistry of Algarve. M. Pessêgo acknowledges FCT for PhD Grant SFRH/BD/60911/2009.
dc.language.isoeng
dc.publisherBeilstein Institute
dc.rights© 2011 Moreira et al; licensee Beilstein-Institut. This is an Open Access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
dc.rights.urihttps://creativecommons.org/licenses/by/2.0/
dc.subjectLinear free-energy relationships
dc.subjectN-methylbenzenesulfonamides
dc.subjectProtonation equilibrium
dc.titleEquilibrium constants and protonation site for N-methylbenzenesulfonamides
dc.typeinfo:eu-repo/semantics/article
dc.identifier.DOI10.3762/bjoc.7.203
dc.relation.publisherversionhttps://doi.org/10.3762/bjoc.7.203
dc.type.versioninfo:eu-repo/semantics/publishedVersion
dc.rights.accessrightsinfo:eu-repo/semantics/openAccess
dc.contributor.affiliationUniversidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares
dc.contributor.affiliationUniversidade de Santiago de Compostela. Departamento de Química Física
dc.description.peerreviewedSI


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© 2011 Moreira et al; licensee Beilstein-Institut. This is an Open Access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Except where otherwise noted, this item's license is described as  © 2011 Moreira et al; licensee Beilstein-Institut. This is an Open Access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited





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