Chapter 9, Problem 9.28P

Interpretation Introduction

Interpretation:

It is to be determined which of the two nucleophiles ${\text{HS}}^{\text{-}}{\text{or HO}}^{-}$ is stronger in water.

Concept introduction:

The strength of a nucleophile, particularly a negatively charged one, is considerably influenced by the nature of the solvent. A protic solvent interacts strongly with a negatively charged nucleophile as the solvent molecule contains at least one hydrogen that has a partial positive charge.

An aprotic solvent in which the atom with a partial positive charge is generally shielded by adjacent groups does not solvate the nucleophile as effectively.

The effective strength of a nucleophile depends on the extent of solvation as strong solvation prevents it from directly approaching the reaction center in the substrate. A number of solvent molecules from its solvation sphere must be lost before it can approach the reaction center close enough to form a bond.