Thermal Aromatizations of 2-Vinylmethylenecyclopropane and 3-Vinylcyclobutene

2012-07-06
Bozkaya, Ugur
Özkan, İlker
A comprehensive theoretical investigation of thermal rearrangements of 2-vinylmethylenecyclopropane and 3-vinylcyclobutene is carried out employing density functional theory and high level ab initio methods, such as the complete active space self-consistent field, multi-reference second-order Moller-Plesset perturbation theory, and coupled-cluster singles and doubles with perturbative triples. In all computations, Pople's polarized triple-zeta split valence basis set, 6-311G(d,p), is utilized. The potential energy surface for the relevant system is explored to provide theoretical insights for the thermal aromatizations of 2-vinylmethylenecyclopropane and 3-vinylcyclobutene. The rate constant for each isomerization reaction is computed using the transition state theory. The simultaneous first-order ordinary-differential equations are solved numerically for the considered system to obtain time-dependent concentrations, hence the product distributions at a given temperature. Our results demonstrate that at high temperatures thermal aromatizations of 2-vinylmethylenecyclopropane (at 700 degrees C and higher) and 3-vinylcyclobutene (at 500 degrees C and higher) are feasible under appropriate experimental conditions. However, at low temperatures (at 500 degrees C and lower), 2-vinylmethylenecyclopropane yields 3-methylenecyclopentene as a unique product, kinetically, and the formation of benzene is not favorable. Similarly, at 300 degrees C and lower temperatures, 3-vinylcyclobutene can only yield trans-1,3,5-hexatriene (major) and cis-1,3,5-hexatriene (minor). At 300 < T < 500 degrees C, 3-vinylcyclobutene almost completely yields 1,3-cyclohexadiene. Hence, our computations provide a useful insight for the synthesis of substituted aromatic compounds. Further, calculated energy values (reaction energies and activation parameters) are in satisfactory agreement with the available experimental results.
Citation Formats
U. Bozkaya and İ. Özkan, “Thermal Aromatizations of 2-Vinylmethylenecyclopropane and 3-Vinylcyclobutene,” pp. 5714–5723, 2012, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/32530.