| Texto completo | |
| Autor(es): |
Monezi, Natalia M.
;
Ando, Romulo A.
Número total de Autores: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Raman Spectroscopy; v. 48, n. 5, p. 758-764, MAY 2017. |
| Citações Web of Science: | 4 |
| Resumo | |
Tetracyanoethylene is an archetypal electron acceptor and in the presence of aromatic amines forms charge transfer -complexes, which subsequently leads to the formation of a tricyanovinylation product by the electrophilic aromatic substitution at para position of tertiary amine ring. Factors as amine concentration and solvent polarity influence both the rate and extension of reaction. In contrast to the aromatic amines containing only one phenyl ring, in the case of N-methyldiphenylamine, the rate of reaction is much slower in particular conditions allowing the spectroscopic characterization (ultraviolet-visible and Raman) of all the species involved, including the neutral adduct and zwitterionic intermediate species. The stabilities of such intermediate species in solution can be controlled by both the concentration of amine and solvent polarity. The results illustrate the dual role played by the amine as a reactant and as a catalyst in the proton abstraction, the rate determining step. The comparison of the reactions in dichloromethane and acetonitrile shows that the neutral adduct and zwitterionic intermediate species are stabilized in nonpolar medium, revealing the role played by the solvent in defining the mechanistic pathways of this model charge transfer initiated reaction. Quantum chemical calculations based on density functional theory and time-dependent density functional theory were used to obtain the theoretical vibrational and electronic spectra and showed fair agreement with experimental data. Copyright (c) 2017 John Wiley \& Sons, Ltd. (AU) | |
| Processo FAPESP: | 12/13119-3 - Espectroscopia vibracional em fases condensadas |
| Beneficiário: | Mauro Carlos Costa Ribeiro |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |