| Full text | |
| Author(s): |
Tormena, Claudio Francisco
[1]
;
Yoshinaga, Fabiana
;
Doi, Telma R.
;
Rittner, Roberto
Total Authors: 4
|
| Affiliation: | [1] Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto. Departamento de Química - Brasil
Total Affiliations: 4
|
| Document type: | Journal article |
| Source: | SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 63, n. 3, p. 511-517, Mar. 2006. |
| Field of knowledge: | Physical Sciences and Mathematics - Chemistry |
| Abstract | |
Conformational preferences and orbital interactions of methyl chloroacetate (1), methyl bromoacetate (2) and methyl iodo-acetate (3) were analyzed using experimental infra-red data, theoretical calculations and NBO analyses. The conformational equilibria of compounds 1-3 can be represented by their cis and gauche rotamers. The gauche form of 1 is stable in the vapour phase and in a non-polar solvent, but the cis is predominant in a polar solvent. For 2 the gauche form is more stable than the cis, in both the vapour and liquid phases, but for compound 3 only the gauche form was observed both in vapour phase as in solution. These conformational preferences were attributed to the orbital interaction between two antibonding orbitals pi(*)(C=O) -> sigma(*)(C-X). This unexpected interaction was possibly due to the high (0.2) electron density on pi(*)(C=O), which results from the interaction between ether oxygen lone pair and pi(*)(C=O). (AU) | |
| FAPESP's process: | 00/07692-5 - Conformational equilibria studies by nuclear magnetic resonance spectroscopy, infrared spectroscopy and theoretical calculations |
| Grantee: | Roberto Rittner Neto |
| Support Opportunities: | Research Projects - Thematic Grants |