104013-07-2Relevant academic research and scientific papers
Energy Barriers to the Diels-Alder Cycloadditions and Cycloreversions of Cation-radicals in the Gas Phase
Turecek, Frantisek,Havlas, Zdenek
, p. 1011 - 1014 (1986)
The mechanism of the retro-Diels-Alder reaction of substituted bicyclohept-2-ene cation-radicals can be related to the energetics of the fragmentation.Concerted synchronous or asynchronous mechanisms are operative in reactions which occur at their thermochemical thresholds.The reverse process, the Diels-Alder reaction of a cation-radical with a molecule, has a negligible activation energy for symmetrical and slightly unsymmetrical systems, +* + cyclopentadiene, +* + vinyl alcohol, +* + cyclopentadiene, and +* + cyclopentadiene.The retro-Diels-Alder decomposition of the highly unsymmetrical 2-vinylbicyclohept-5-en-2-ol cation-radical proceeds in two steps and overcomes a barrier of 58-67 kJ mol-1 above the thermochemical threshold.The effect of bond-dissociation energies on the reaction mechanism is discussed.
