An experimental approach to the C8H10 hypersurface. Kinetic and thermochemical investigations on a formally forbidden ground‐state [2σ + 2π] cycloaddition
- 1 February 1987
- journal article
- research article
- Published by Wiley in European Journal of Inorganic Chemistry
- Vol. 120 (2) , 177-186
- https://doi.org/10.1002/cber.19871200209
Abstract
The C8H10 hydrocarbons 1, 3, 4, and 6 have been thermolyzed in a static system and the Arrhenius parameters have been obtained. Calorimetric measurements have been carried out to determine the heats of formation. From these data an experimental energy hypersurface is constructed which shows the following remarkable features: 1) The ground‐state energy of endo‐1 is higher than that of exo‐4 by 8 kcal mol−1. 2) The predominant reaction pathway of endo‐1 is the formally forbidden [2σ + 2π] cycloaddition to 3, the mechanism of which is discussed. 3) Although the activation energies of the routes 4→6 and 4→3 are the same, the reaction yielding 6 is faster due to a sizeably higher A factor. 4) The tetracycle 3 chooses the microscopic reverse pathway, i.e. its thermolysis proceeds via exo‐4 to give the diene 6.Keywords
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