Isotope Effects in the Solvolysis of Sterically Hindered Arenesulfonyl Chlorides

Article abstract of DOI:10.1002/kin.20945

Solvent isotope effects in the ethanolysis of sterically hindered arenesulfonyl chlorides ruled out a proton transfer in the rate-determining step and agreed with a S_N2 mechanism involving at least a second solvent molecule in the transition state (TS). The lack of a secondary kinetic isotope effect in the o-alkyl groups allows us to disregard the possible contribution of σ-π hyperconjugation. The measured activation parameters are consistent with a S_N2 mechanism involving the participation of solvent molecules in the TS, possibly forming a cyclic TS through a chain of solvent molecules.