Theoretical study of the gas‐phase addition of HF and HCl to ethylene: Analysis of the catalytic action of dimeric halides

Ab initioMP2/6‐31G** calculations render the same mechanism for the gas‐phase addition of HF and HCl to ethylene in contrast with previous HF/3‐21G calculations. The leading interaction is in both cases the electrophilic attachment of the hydrogen atom in the hydrogen halide to a carbon atom in ethylene. The presence of a second molecule of hydrogen halide causes a catalytic effect by allowing an alternative mechanism for electron density rearrangement through ethylene polarization.