Evidence for Walden inversion in high energy chlorine-for-chlorine substitution reactions

The stereochemistry of high energy chlorine-for-chlorine substitution was studied in gaseous and condensed phase 2(S)-chloropropionyl chloride and 2(R)-chloropropionyl chloride. Greater than 80% inversion of configuration was observed at the chiral center for both high energy 38Cl and /sup 34m/Cl substitution. Net retention is observed in gaseous 2(S)-chloro-4-methylvaleryl chloride where steric hindrance to backside attack is enhanced relative to 2(S)-chloropropionyl chloride. Condensed state data suggest caged radical recombination reactions. 2 tables