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|Type:||Artigo de periódico|
|Title:||Conformational and electronic interaction studies of p-substituted alpha-phenoxyacetones|
|Abstract:||The nu(CO) analysis of p-substituted alpha-phenoxy-acetones X-phi-O-CH2-C(O)-Me (1-6) indicates the existence of the cis/gauche rotational isomerism. The nearly constant increase in the cis/gauche population ratios for the whole series, on going from carbon tetrachloride to acetonitrile, and the small sensitivity of the carbonyl frequency shifts (Delta nu(C)) for the cis rotamer, on going from electron-attracting to electron-donating substituents, are interpreted as an interplay of the Field (F) and the inductive (-I) Effects, which originates an almost constant carbonyl bond order, and suggests that the cis rotamers have almost the same energy in the whole series. The decrease in the cis/gauche population ratios, in all solvents, and the deshielding effects on the carbonyl carbon atom, and on the methylene carbon atom in a weaker extent, observed in the C-13 NMR spectra, on going from electron-attracting to electron-donating substituents, are discussed in terms of pi*(CO)/n(O) orbital and Ardelta+-Odelta- - Cdelta+=Odelta- Coulombic, interactions, which stabilize the gauche rotamers of the investigated compounds.|
|Editor:||Marcel Dekker Inc|
|Appears in Collections:||Artigos e Materiais de Revistas Científicas - Unicamp|
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