Stereoelectronic and inductive effects on H-1 and C-13 NMR chemical shifts of some cis-1,3-disubstituted cyclohexanes

dc.creatorde Oliveira, PR
dc.creatorTasic, L
dc.creatorRocco, SA
dc.creatorRittner, R
dc.date2006
dc.dateAUG
dc.date2014-11-19T00:02:45Z
dc.date2015-11-26T17:55:01Z
dc.date2014-11-19T00:02:45Z
dc.date2015-11-26T17:55:01Z
dc.date.accessioned2018-03-29T00:38:47Z
dc.date.available2018-03-29T00:38:47Z
dc.identifierMagnetic Resonance In Chemistry. John Wiley & Sons Ltd, v. 44, n. 8, n. 790, n. 796, 2006.
dc.identifier0749-1581
dc.identifierWOS:000239318700008
dc.identifier10.1002/mrc.1850
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/75203
dc.identifierhttp://www.repositorio.unicamp.br/handle/REPOSIP/75203
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/75203
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1290924
dc.descriptionThis work presents the substituent effects on the H-1 and C-13 NMR chemical shifts in the cis-isomer of 3-Y-cyclohexanols (Y = Cl, Br, I, CH3, N(CH3)(2) and OCH3) and 3-Y-1-methoxycyclohexanes (Y = F, Cl, Br, I, CH3, N(CH3)(2) and OCH3). It was observed that the H-3 chemical shift, due to the substituent alpha-effect, increases with the increase of substituent electronegativity when Y is from the second row of the periodic table of elements, (CH3 <N(CH3)(2) <OCH3 <F) and decreases with the increase of electronegativity when Y is a halogen (Cl < Br < I). The natural bond orbital (NBO) analysis showed that the alpha-effect on the H-3 chemical shift increases with the decrease of n(Y) --> *sigma(C3-H3a) interaction energy. This interaction energy, for the halogenated compounds, decreases with an increase in size of the halogen, and this is a possible reason for the largest measured chemical shift for H-3 of the iodo-derivatives. The beta-effect of the analyzed compounds showed that the chemical shift of hydrogens at C-2 and C-4 increases with the decrease of n(Y) --> *sigma(C2-C3) and n(Y) --> *sigma(C3-C4) interaction energies, respectively, showing a behavior similar to H-3. The alpha-effect on C-13 chemical shifts correlates well with substituent electronegativity, while the beta-effect is inversely related to electronegativity in halogenated compounds. NBO analysis indicated that the substituent inductive effect is the predominant effect on C-13 NMR chemical shift changes for the alpha-carbon. It was also observed that C-2 and C-4 chemical shifts for compounds with N(CH3)(2), OCH3 and F are more shielded in comparison to the compounds having a halogen, most probably because of the larger interaction of the lone pair of more electronegative atoms (n(N) > n(O) > n(F)) with *sigma(C2-C3), *sigma(C3-C4) and *sigma(C3-H3a) in comparison with the same type of interaction with the lone pair of the other halogens. Copyright (C) 2006 John Wiley & Sons, Ltd.
dc.description44
dc.description8
dc.description790
dc.description796
dc.languageen
dc.publisherJohn Wiley & Sons Ltd
dc.publisherChichester
dc.publisherInglaterra
dc.relationMagnetic Resonance In Chemistry
dc.relationMagn. Reson. Chem.
dc.rightsfechado
dc.rightshttp://olabout.wiley.com/WileyCDA/Section/id-406071.html
dc.sourceWeb of Science
dc.subjectH-1 NMR
dc.subjectC-13 NMR
dc.subjectstereoelectronic effect
dc.subject1,3-disubstituted cyclohexanes
dc.subjectchemical shifts
dc.subjectnatural bond orbital (NBO) analysis
dc.subjectNuclear-magnetic-resonance
dc.subjectCoupling-constants
dc.subject6-membered Heterocycles
dc.subjectGamma-substituent
dc.subjectDensity
dc.subjectShieldings
dc.subjectExchange
dc.subjectSpectra
dc.titleStereoelectronic and inductive effects on H-1 and C-13 NMR chemical shifts of some cis-1,3-disubstituted cyclohexanes
dc.typeArtículos de revistas


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