Chapter 7, Problem 57P

Interpretation Introduction

Interpretation:

The structure of the resulting azide is to be determined and the difference in reactivity between the two diastereomers is to be explained.

Concept introduction:

Azide is an ionic base and a good nucleophile, so the mechanisms of substitution/elimination reaction using azide will be ${\text{S}}_{\text{N}}\text{2/E2}$ when the substrate is a secondary alcohol (or toluene sulfonate ester).

In $\text{E2}$ elimination, the proton and the other group being eliminated must be axial and anti to each other.

In ${\text{S}}_{\text{N}}\text{2}$

mechanism, the nucleophile approaches from the less hindered side.

The anti-coplanar geometry of the beta proton and the leaving group increase the rate of elimination reaction.

The low level of steric hindrance increase the rate of substitution reaction.