Theoretical Kinetic Study of the Ring Opening of Cyclic Alkanes

This work reports a theoretical study of the gas phase unimolecular decomposition of cyclobutane, cyclopentane and cyclohexane by means of quantum chemical calculations. A biradical mechanism has been envisaged for each cycloalkane, and the main routes for the decomposition of the biradicals formed have been investigated at the CBS-QB3 level of theory. Thermochemical data (?H\degree f, S\degree, C\degree p) for all the involved species have been obtained by means of isodesmic reactions. Rate constants have been derived for all elementary reactions using transition state theory at 1 atm and temperatures ranging from 600 to 2000 K. These values have been compared with the few data available in the literature and showed a rather good agreement.