Chapter 10, Problem 10.1YT

Interpretation Introduction

Interpretation:

Using ${\text{PCl}}_{\text{3}}$ instead of ${\text{PBr}}_{\text{3}}$ in equation $\text{10-8}$, new mechanism is to be drawn.

Concept introduction:

In equation $\text{10-8}$, alcohol is converted into alkyl bromide via two back-to-back ${\text{S}}_{\text{N}}2$ reactions. In this reaction, inversion of configuration takes place.

In ${\text{S}}_{\text{N}}2$ reaction, nucleophilic substitution takes place in a single step. In this reaction, bond formation between the nucleophile and substrate and bond breaking between the leaving group and substrate take place simultaneously. Due to the backside attack of the nucleophile, inversion of configuration takes place.

${\text{PBr}}_{\text{3}}$ and ${\text{PCl}}_{\text{3}}$ convert the alcohol into an alkyl halide under relatively mild conditions.