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dc.contributor.author | Moreira, José A. |
dc.contributor.author | Costa, Ana M. Rosa da |
dc.contributor.author | García Río, Luis |
dc.contributor.author | Pessêgo, Márcia Isabel Duarte |
dc.date.accessioned | 2020-05-20T08:12:27Z |
dc.date.available | 2020-05-20T08:12:27Z |
dc.date.issued | 2011 |
dc.identifier.citation | Moreira, 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.issn | 1860-5397 |
dc.identifier.uri | http://hdl.handle.net/10347/22450 |
dc.description.abstract | The 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.sponsorship | This 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.iso | eng |
dc.publisher | Beilstein 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.uri | https://creativecommons.org/licenses/by/2.0/ |
dc.subject | Linear free-energy relationships |
dc.subject | N-methylbenzenesulfonamides |
dc.subject | Protonation equilibrium |
dc.title | Equilibrium constants and protonation site for N-methylbenzenesulfonamides |
dc.type | journal article |
dc.identifier.doi | 10.3762/bjoc.7.203 |
dc.relation.publisherversion | https://doi.org/10.3762/bjoc.7.203 |
dc.type.hasVersion | VoR |
dc.rights.accessRights | open access |
dc.contributor.affiliation | Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares |
dc.contributor.affiliation | Universidade de Santiago de Compostela. Departamento de Química Física |
dc.description.peerreviewed | SI |
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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
© 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