Conformational and electronic interaction studies of some alpha-mono-heterosubstituted carbonyl compounds

dc.creatorOlivato, PR
dc.creatorRittner, R
dc.date1996
dc.date2014-07-30T14:00:40Z
dc.date2015-11-26T16:33:42Z
dc.date2014-07-30T14:00:40Z
dc.date2015-11-26T16:33:42Z
dc.date.accessioned2018-03-28T23:15:41Z
dc.date.available2018-03-28T23:15:41Z
dc.identifierReviews On Heteroatom Chemistry. Myu K K, v. 15, n. 115, n. 159, 1996.
dc.identifier0915-6151
dc.identifierWOS:A1996VV52900006
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/56521
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/56521
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1270954
dc.descriptionnu(CO) frequencies and intensities of some alpha-heterosubstituted carbonyl compounds [XCH(2)C(O)Y: X = F, OMe, NR(2), Cl, Br, SEt, or I; and Y = Me, Ph, SR, OMe or NEt(2)], together with molecular mechanics calculations indicated the existence of cis-gauche rotational isomerism. In solvents of low polarity the gauche rotamers predominate over the cis ones, except for the fluoro and methoxy derivatives of acetophenone and methyl acetate series. The progressive increase in the gauche rotamer population in each series, on going from the fluoro to the iodo derivative has been mainly ascribed to the increasing contribution of the pi*(CO)/sigma(C-X) and pi*(CO)/n(X) orbital interactions. The carbonyl frequency shifts of the cis rotamers are interpreted as being due to the substituent field and inductive effects, while the corresponding shifts of the gauche rotamers have been attributed to an interplay of inductive and hyperconjugative effects. The carbonyl shifts induced by inductive (Delta nu(I)), field (Delta nu(F)) and hyperconjugative effects (Delta nu(H)) were estimated separately for the acetone derivatives. The larger negative carbonyl gauche shifts (Delta nu(g)) along with a higher non-additivity effect (Delta delta) of the alpha-methylene carbon chemical shifts can be associated with stronger pi*(CO)/sigma(C-X) and pi*(CO)/n(X) orbital interactions. The higher stabilization of the gauche rotamers for the alpha-akylthio carbonyl compounds, the larger nu(CO) gauche shifts and the lower non-additivity effect for the alpha-methylene carbon have been interpreted as being due to the simultaneous occurrence of pi*(CO)/sigma(C-S) and pi(CO)/sigma*(C-S) orbital interactions. The progressive bathochromic shifts of n(O) --> pi*(CO) transition for the alpha-heterosubstituted ketones, on going from the fluorine to the iodine substituent, were mainly ascribed to a contribution of the hyperconjugative interaction (pi*(CO)/sigma*(C-X)). Ab initio calculations, and photoelectron and electron transmission spectroscopies have supported, in general, the mentioned orbital interactions.
dc.description15
dc.description115
dc.description159
dc.languageen
dc.publisherMyu K K
dc.publisherTokyo
dc.publisherJapão
dc.relationReviews On Heteroatom Chemistry
dc.relationRev. Heteroatom Chem.
dc.rightsfechado
dc.sourceWeb of Science
dc.subjectalpha-heterosubstituted carbonyl compounds
dc.subjectconformational isomerism
dc.subjectelectronic interactions
dc.subjectSolution-state Conformations
dc.subjectVibrational Assignment
dc.subjectInternal-rotation
dc.subjectUltraviolet Photoelectron
dc.subjectAbinitio Calculations
dc.subjectMolecular-mechanics
dc.subjectMicrowave-spectrum
dc.subjectIr Spectroscopy
dc.subjectFluoroacetone
dc.subjectDerivatives
dc.titleConformational and electronic interaction studies of some alpha-mono-heterosubstituted carbonyl compounds
dc.typeArtículos de revistas


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