| Journal: | Journal of the Brazilian Chemical Society |
| Database: | PERIÓDICA |
| System number: | 000310995 |
| ISSN: | 0103-5053 |
| Authors: | Basso, Ernani A1 Oliveira, Paulo R Caetano, Josiane Schuquel, Ivania T.A |
| Institutions: | 1Universidade Estadual de Maringa, Departamento de Quimica, Maringa, Parana. Brasil |
| Year: | 2001 |
| Season: | Abr |
| Volumen: | 12 |
| Number: | 2 |
| Pages: | 215-222 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Artículo |
| Approach: | Experimental, aplicado |
| English abstract | Axial-equatorial conformational proportions for cyclohexyl-N,N-dimethyl carbamate have been measured, for the first time, by the Eliel method, ¹H and 13C dynamic nuclear magnetic resonance (DNMR). The results were compared against those determined by theoretical calculations. By the Eliel method at least five experimentally independent measureables were used in CCl4, CDCl3 and CD3CN. The ¹H and 13C low temperature experiments were performed in CF2Br2/CD2Cl2 . Semiempirical methods MNDO, AM1 and PM3 and ab initio molecular orbital calculations at the HF/STO-3G and HF/6-31G(d,p) levels have been performed on the axial and equatorial conformers populations. All applied methods correctly predict the equatorial conformer preference over the axial one. The resulting equatorial preferences determined by NMR data and theoretical calculations are in good agreement |
| Portuguese abstract | As proporções dos confôrmeros axial-equatorial do N,N-dimetilcarbamato de cicloexila foram determinadas, pela primeira vez, pelo método de Eliel, pela ressonância magnética nuclear dinâmica(rmnd) de ¹H e de 13C e foram comparados com resultados obtidos através de cálculos teóricos. Pelo método de Eliel foram utilizados pelo menos cinco parâmetros experimentais independentes, em CCl4, CDCl3 e CD3CN. Os experimentos de ¹H e de 13C a baixas temperaturas foram realizados em CF2Br2/CD2Cl2. Os métodos semiempíricos MNDO, AM1 e PM3 e cálculos ab initio de orbital molecular nos níveis HF/STO-3G e HF/6-31G(d,p) também foram utilizados. Tanto os métodos que utilizaram a RMN como os cálculos teóricos corretamente indicaram a preferência do confôrmero equatorial em relação ao axial e os valores obtidos pelos diferentes métodos demonstraram boa concordância |
| Disciplines: | Química |
| Keyword: | Química analítica, Química orgánica, Ciclohexano, Ciclohexil-N,N-dimetilcarbamato, Análisis conformacional, Resonancia magnética nuclear |
| Keyword: | Chemistry, Analytical chemistry, Organic chemistry, Cyclohexane, Cyclohexyl-N,N-dimethylcarbamate, Conformational analysis, Nuclear magnetic resonance |
| Full text: | Texto completo (Ver HTML) |
