Study of trichloromethyl radical proton abstraction reaction with ab initio and density functional theory methods

The validity of both ab initio and density functional theory (DFT) methods for evaluating the activation energies of the radical proton abstraction reaction is discussed. The activation energies for trichloromethyl radical hydrogen abstraction from methane, ethane, propane, and 2-methylpropane are computed with two ab initio (HF and MP2), two hybrid (BHandHLYP and Becke3LYP) and one non-local (BLYP) DFT method. All calculations are performed with a 6-31G(d) basis set; the obtained results are compared with experimentally determined activation barriers. The non-local BLYP DFT method is selected as one that will produce reliable activation energies.