Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/63338
Type: Artigo de periódico
Title: C-13 NMR, infrared, solvation and theoretical investigation of the conformational isomerism in 1-haloacetones (X = Cl, Br and I)
Author: Doi, TR
Yoshinaga, F
Tormena, CF
Rittner, R
Abraham, RJ
Abstract: The solvent dependence of the C-13 NMR spectra of chloroacetone (CA), bromoacetone (BA) and iodoacetone (IA) are reported and the (3)J(CH) couplings analysed using ab initio calculations and solvation theory. In CA the energy difference (E-cis - E-gauche) between the cis (Cl-C-C=O 0 degrees) and gauche (Cl-C-C=O 155 degrees) conformers is 1.7 kcal mol(-1) in the vapour, decreasing to 0.8 kcat mol(-1) in CCl4 solution and to - 1.0 kcal mol(-1) in the pure liquid. The conformational equilibrium, in BA, is between the more polar cis (Br-C-C=O 0 degrees) and gauche (Br-C-C=O 132 degrees) conformations. The energy difference (E-cis - E-gauche) is 1.8 kcal mol(-1) in the vapour, decreasing to 0.9 kcal mol(-1) in CCl4 solution and to -0.4 kcal mol(-1) in the pure liquid. The energy difference (Ecis - Egauche), in IA, between the cis (Cl-C-C=O 0 degrees) and gauche (I-C-C=O 104 degrees) conformers is 1.1 kcal mol(-1) in the vapour phase, decreasing to 0.5 kcal mol(-1) in CCl4 solution and to -0.5 kcal mol(-1) in the pure liquid. The vapour state energy difference for BA [1.4 kcal mol(-1) at B3LYP/6-311++G(d,p)] and for IA [1.6 kcal mol(-1) at B3LYP/6-311++G(d,p)/LANL2DZ)] are in very good agreement with the above values. For CA the agreement is also satisfactory [1.4 kcal mol(-1) at B3LYP/6-311++G(d,p)]. (c) 2004 Elsevier B.V. All rights reserved.
Subject: conformational analysis
NMR spectroscopy
theoretical calculations
haloacetones
Country: Inglaterra
Editor: Pergamon-elsevier Science Ltd
Rights: fechado
Identifier DOI: 10.1016/j.saa.2004.08.021
Date Issue: 2005
Appears in Collections:Unicamp - Artigos e Outros Documentos

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