Chapter 16, Problem 34P

Interpretation Introduction

Interpretation:

The correct enantiomer of $\text{2-butanol}$ that can be used to prepare $\left(\text{R}\right)\text{-2-butanethiol}$ by way of a $\text{p-toluenesulfonate}$ is to be identified and a chemical equation for each step is to be written.

Concept introduction:

The alcohols on reaction with $\text{p-toluenesulfonyl chloride}$ give $\text{p-toluenesulfonate}$.

As the hydroxyl group of alcohol acts as a nucleophile, there is no change in configuration of alcohol and tosylate ($\text{p-toluenesulfonate}$) forms with retention of configuration of alcohol.

The thiol can be prepared from $\text{p-toluenesulfonate}$ by nucleophilic substitution through ${\text{S}}_{\text{N}}\text{2}$ mechanism using the conjugate base of ${\text{ H}}_{\text{2}}\text{S}$$\left(\text{KSH}\right)$.

The ${\text{S}}_{\text{N}}\text{2}$ reaction proceeds with inversion in configuration of product as that in reactant.