Mechanisms and reaction-path dynamics of hydroxyl radical reactions with aromatic hydrocarbons: The case of chlorobenzene

Tropospheric Degradation of Perfluorinated Aromatics: A Case of Hexafluorobenzene

“…These degrees of freedom were treated as internal rotors and barrier of the internal rotation was calculated by scanning the rotational potential of the OH group. Furthermore, as demonstrated in our previous studies, [10,12] the relative translation of OH radical with respect to hexafluorobenzene in the prereaction complex was treated as a two-dimensional particle-in-the-box and the box size was set at 2.8 Å which is the diameter of benzene ring. Energy transfer, used in the Gillespie stochastic modeling, between prereaction complex and bath gas was modeled with the exponential down collision model at pressure of 1 atmosphere.…”

“…Energy transfer parameters are unknown for this system and a value of 175 cm -1 was assumed for exponential down model by analogy with monohalogenated benzenes. [10,12] Energy density was integrated by double array integration scheme with 7 cm -1 energy grain. The maximum energy from the coarser part of the double array was fixed at 85000 cm -1 .…”

“…In our previous studies on monosubstituted halobenzenes, [10,12] it was proven that theoretical methods MP2 and G3 can give relevant information on the reaction mechanism of OH radical addition to haloaromatic systems as well as on the corresponding thermodynamic data. Those results coupled with the RRKM (Rice-RamspergerKassel-Marcus) kinetic theory have also successfully reproduced the experimental reaction rates.…”

“…Contrary to this, the number of studies on aromatic compounds is quite limited. The detailed investigations on reaction mechanisms and reaction kinetics are available only for benzene, [7,8] toluene, [9] fluorobenzene, [10] chlorobenzene, [11,12] phenol [13] and naphthalene. [14] The major reason for a small number of studies on aromatic compounds is their significant size and complex reaction mechanism with OH radicals, thus sophisticated theoretical methods must be used in order to obtain meaningful results.…”

“…[18,20,21] In the last several years, we are extending those research efforts into the tropospheric degradation reactions of halogenated aromatic hydrocarbons and were successful in modeling gas-phase reactions of OH radicals with fluorobenzene [10] and chlorobenzene. [12] This study on hexafluorobenzene is the next step in our endeavor to produce methodology for calculating the tropospheric degradation rates of persistent organic pollutants (POPs), [22,23] normally perhalogenated or polyhalogenated biphenyls, diphenylethers, dibenzo-p-dioxins or -furans, and analogous chemicals (DDT, chlordane, heptachlor).…”