Chapter 18.6, Problem 4P

Interpretation Introduction

Interpretation:

A mechanism for the generation of the acylium ion when an acid anhydride is used instead of an acyl chloride for the source of the acylium ion has to be shown.

Concept Introduction:

For the generation of the acylium ion, an acid chloride or an acid anhydride is taken as the source of the acyl group. Such process is called Friedel-Crafts acylation process.  For this process an acylium ion is required as an electrophile.  This ion is formed by the reaction of an acid chloride or an acid anhydride with ${\text{AlCl}}_{\text{3}}$.  Here, ${\text{AlCl}}_{\text{3}}$ behaves as a Lewis acid.