A DFT study on the C-H bond dissociation enthalpies of haloalkanes: Correlation between the bond dissociation enthalpies and activation energies for hydrogen abstraction

The C-H bond dissociation enthalpies of halomethanes were computed from the results of density functional theory (DFT) calculations at the B3LYP level with various basis sets, such as 6-311G(d,p) and 6-311++G-(3df.2p). Reasonably accurate C-H bond dissociation enthalpies were obtained even at the B3LYP/6-311G-(d,p) level when ROB3LYP method was used for radicals. Applying the same procedure, the C-H bond dissociation enthalpies for a series of haloethanes were also calculated. Good correlation has been observed between the activation energies for the hydrogen abstraction from haloalkanes by OH radical and the corresponding C-H bond dissociation enthalpy values.