Possible Skeletal Transformations of Cyclooctatetraene in Its Thermal Isomerization

All possible transition state structures that could mediate thermally induced skeletal transformations of cyclooctatetraene in an oxygen-free atmosphere have been identified on the basis of the properties of the π-conjugated system in cyclic polyenes. DFT study of the potential energy surface and the nature of localized stationary points using the B3LYP functional and 6-31G* basis set confirmed the existence of 30 transition states. A scheme for the thermal isomerization of cyclooctatetraene, which includes 47 forward and reverse reactions, was constructed by the Gonzalez–Schlegel method for the determination of potential barriers. The obtained results were consistent with the available experimental data.