Activation parameter changes as a mechanistic tool in SN2 reactions in solution

Abstract

Recent applications of activation parameters variation approach to the elucidation of S N 2 reaction mechanisms have led to further clarifications of structures of transition states involved in the concerted reaction pathway. S N 2 reactions in solution are reviewed with special emphasis of activation parameter variation Δ X ≠ ( X = H , S and G ) with substituents in the nucleophile, leaving and nonleaving groups applying linear free energy relationships in order to evaluate the resultant δΔ X ≠ reaction constants. The use of internal enthalpy reaction constants δΔ H ≠ int as a mechanistic tool is stressed when the structure of transition state in S N 2 reaction is changed. Variations of the activation parameters in S N 2 reactions and their mechanisms were analyzed.