| Autor: |
Nunes PM; Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal., Estácio SG, Lopes GT, Agapito F, Santos RC, Costa Cabral BJ, Borges dos Santos RM, Martinho Simões JA |
| Jazyk: |
angličtina |
| Zdroj: |
The journal of physical chemistry. A [J Phys Chem A] 2009 Jun 11; Vol. 113 (23), pp. 6524-30. |
| DOI: |
10.1021/jp900089t |
| Abstrakt: |
The energetics of tert-butoxyl radical addition reaction to norbornadiene was investigated by time-resolved photoacoustic calorimetry (TR-PAC). The result, together with the C-O bond dissociation enthalpy (BDE) in the addition product, allowed us to calculate the pi-bond dissociation enthalpy in norbornadiene. Quantum chemistry (QC) methods were also used to obtain several enthalpies of reaction of the addition of oxygen-centered radicals to alkenes. The pi-bond dissociation enthalpies in these molecules were calculated by a procedure similar to that used in the case of norbornadiene and were compared with the pi-BDE values obtained by the method proposed by Benson. These two different approaches yield similar values for the pi-BDEs in alkenes, indicating that the addition method proposed in the present study is a valid way to derive that quantity. The influence of strain in the pi-BDEs of cyclic alkenes was investigated and allowed us to justify the difference between the pi-BDE in norbornene and norbornadiene. Finally, the thermochemistry of the addition and abstraction reactions involving these two molecules and tert-butoxyl radical was analyzed. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
|
