Chapter 22, Problem 22.32P

Interpretation Introduction

Interpretation:

The reactant in the reaction given is aromatic and will undergo electrophilic aromatic substitution in much the same way that benzene does. This reaction leads to a single product. The reason for it is to be explained. The product of the reaction is to be predicted and the complete, detailed mechanism for its formation is to be drawn.

Concept introduction:

For electrophilic aromatic substitution, a benzene carbon must contain H atoms. Formylation take place when benzene is treated with acyl halide in the presence of ${\text{AlCl}}_{\text{3}}$, which is a strong Lewis acid catalyst. The reaction is called Friedel–Crafts acylation. In Step 1, acyl halide coordinates to Al atom of ${\text{AlCl}}_{\text{3}}$. In Step 2, X-C bond breaks in a heterolysis step, which takes place slowly, yielding the carbocation electrophile. The final two steps are the electrophilic aromatic substitution steps i.e. electrophilic addition-elimination. The product is aromatic ketone.