| Autor: |
IVAN O. JURANIC, ARMIN DE MEIJERE, GORDANA S. USCUMLIC, SERGEI I. KOZHUSHKOV, ZELJKO VITNIK, NATASA V. VALENTIC |
| Jazyk: |
angličtina |
| Rok vydání: |
2003 |
| Předmět: |
|
| Zdroj: |
Journal of the Serbian Chemical Society, Vol 68, Iss 2, Pp 67-76 (2003) |
| Druh dokumentu: |
article |
| ISSN: |
0352-5139 |
| Popis: |
The principles of linear free energy relationships were applied to the 13C substituent chemical shifts (SCS) of the carbon atoms in the unsaturated chain of 3-methylene-4-substituted-1,4-pentadienes. Correlations of the SCS with the substituent parameters of Swain and Lupton provide a mutually consistent picture of the electronic effects in these compounds. The pattern of the electronic effects can be fully rationalized by a model based on the direct transmission of substituent effects through-space (direct through-space field effects), and via conjugative interactions (resonance effects), or by substituent-induced polarization of the p-system in the unsaturated chain (p-polarization effect). Semi-empirical MNDO-PM3 calculations suggest the s-cis conformation of 3-methylene-4-substituted-1,4- -pentadienes as the one with minimal heat of formation. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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