Chapter 21, Problem 21.4YT

Interpretation Introduction

Interpretation:

The missing steps of the partial mechanism shown in Equation $\text{21-18}$ is to be drawn.

Concept introduction:

The phosphorus on reaction with bromine produces phosphorus tribromide. In first step, pphosphorus tribromide converts the carboxylic acid into an acyl bromide. An acyl bromide can freely appears in the enol form. This tautomer is immediately brominated at the $\text{α-carbon}$.