Chapter 9, Problem 9.20P

Interpretation Introduction

Interpretation: The stereochemistry of the alkyl chloride formed by the reaction of $\left(\text{R}\right)\text{-butan-2-ol}$ with $\left({\text{SOCl}}_2\right)$ and pyridine is to be stated.

Concept introduction: Alkyl chlorides are obtained by the reaction of ${\text{1}}^{\text{ο}}\text{or}{\text{2}}^{\text{ο}}$ alcohols with thionyl chloride $\left({\text{SOCl}}_2\right)$, and pyridine. The reaction yields ${\text{SO}}_{\text{2}}$, and $\text{HCl}$ as by-products. The mechanism of the reaction involves two steps. The first step is conversion of the $\text{OH}$ group into a good leaving group. The second step is nucleophilic attack by ${\text{Cl}}^{-}$ through an ${\text{S}}_{\text{N}}2$ reaction. This ${\text{S}}_{\text{N}}2$ reaction results inversion of stereochemistry at stereogenic center.