Stereochemical Consequences of Halogen-for-Halogen Substitutions in the Gas Phase

Article abstract of DOI:10.1021/j150642a032

The stereochemistry of translationally energetic fluorine-for-halogen and chlorine-for-halogen substitution was studied in gaseous 2(S)- and 2(R)-halopropionyl halides.While net inversion of configuration was observed for halogen using ^34mCl as the displacing agent, predominant retention of configuration was found when 18F was used as the displacing agent on the chiral centers of the 2-halopropionyl halides.The extent of inversion or retention in these energetic substitution reactions appears to be sensitive to the mass of the incoming atom, to steric hindrance to back-side attack, and to the nature of the halogen leaving group.