NMR, solvation and theoretical investigations of conformational isomerism in 2-X-cyclohexanones (X = NMe2, OMe, SMe and SeMe)

dc.creatorFreitas, MP
dc.creatorTormena, CF
dc.creatorGarcia, JC
dc.creatorRittner, R
dc.creatorAbraham, RJ
dc.creatorBasso, EA
dc.creatorSantos, FP
dc.creatorCedran, JC
dc.date2003
dc.dateNOV
dc.date2014-11-14T13:41:15Z
dc.date2015-11-26T17:15:17Z
dc.date2014-11-14T13:41:15Z
dc.date2015-11-26T17:15:17Z
dc.date.accessioned2018-03-29T00:03:32Z
dc.date.available2018-03-29T00:03:32Z
dc.identifierJournal Of Physical Organic Chemistry. John Wiley & Sons Ltd, v. 16, n. 11, n. 833, n. 838, 2003.
dc.identifier0894-3230
dc.identifierWOS:000186101000001
dc.identifier10.1003/poc.664
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/61930
dc.identifierhttp://www.repositorio.unicamp.br/handle/REPOSIP/61930
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/61930
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1282009
dc.descriptionThe conformational equilibria of 2-N,N-dimethylamino- (1), 2-methoxy- (2), 2-methylthio- (3) and 2-methylselenocyclohexanone (4) were determined in various solvents by measurement of the (3)J(H-2,H-3) couplings. The observed couplings were analyzed using theoretical and solvation calculations to give both the conformer energies in the solvents studied plus the vapor-phase energies and the coupling constants for the distinct conformers. These gave the conformer energies and couplings of 2-4. The intrinsic couplings for the 2-N,N-dimethylamino compound were determined by the molecular mechanics PCMODEL program. The axial conformation in 1 is the most polar and also more stable in DMSO solution (E-eq - E-ax = 0.05 kcal mol(-1)) and the pure liquid, while the equatorial conformer predominates in the remaining solvents studied (except in CCl4, where self-association is observed). In the methoxy ketone (2) the equatorial conformation is more stable in the vapor (E-eq - E-ax = -0.30 kcal mol(-1)) and in all solvents. The opposite behavior is shown by 3 and 4, where the axial conformation is the more stable one in the vapor phase (E-eq - E-ax = 1.60 and 2.95 kcal mol(-1) for 3 and 4, respectively) and is still the prevailing conformer in solution. The axial predominance for 3 and 4 is attributed to hyperconjugation between the electron lone pair of the heterosubstituent and the pi*(CO) orbital. This interaction is stronger for 3 and 4 than in the case of 1 and 2, where the 'gauche effect' in the equatorial conformation should be more effective in stabilizing this conformation. Copyright (C) 2003 John Wiley Sons, Ltd.
dc.description16
dc.description11
dc.description833
dc.description838
dc.languageen
dc.publisherJohn Wiley & Sons Ltd
dc.publisherChichester
dc.publisherInglaterra
dc.relationJournal Of Physical Organic Chemistry
dc.relationJ. Phys. Org. Chem.
dc.rightsfechado
dc.rightshttp://olabout.wiley.com/WileyCDA/Section/id-406071.html
dc.sourceWeb of Science
dc.subjectconformational analysis
dc.subject2-substituted cyclohexanones
dc.subjectNMR spectroscopy
dc.subjecttheoretical calculations
dc.subjectsolvation theory
dc.subject2-substituted Cyclohexanones
dc.subjectStereochemical Consequences
dc.subjectInfrared-spectroscopy
dc.subjectOrganic-molecules
dc.subjectIr
dc.subject2-bromocyclohexanone
dc.subjectAcetone
dc.subjectPairs
dc.titleNMR, solvation and theoretical investigations of conformational isomerism in 2-X-cyclohexanones (X = NMe2, OMe, SMe and SeMe)
dc.typeArtículos de revistas


Este ítem pertenece a la siguiente institución