Substitution rates and equilibria of ethoxide, methoxide and hydroxide ions in various solvents

Abstract

The rates of bimolecular substitutions and eliminations depend on the nucleophilic character of the reagent. If we may gauge nucleophilic character by basicity, then a series of reagents, such as OH- , OPh- , OAc- , Br- should correspond to a decreasing relative tendency towards bimolecular reactions. Since this series is based on , nucleophilic affinity for a proton, it may be expected to express fairly well the relative activity of the reagents in bimolecular elimination, when the attack is on a hydrogen atom. In the case of bimolecular nucleophilic substitution the activity of the reagents may not be expressed so well. The general theory is that strong bases are strong nucleophilic reagents and weak bases are weak nucleophilic reagents. However, the strength of a base is determined by the readiness with which it will transfer a pair of electrons to a hydrogen atom