Chapter 22, Problem 22.30P

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for the given reaction is to be drawn. If the product be optically active is to be determined.

Concept introduction:

Alkylation take place when benzene is treated with an alkyl halide in the presence of ${\text{AlCl}}_{\text{3}}$, which is a strong Lewis acid catalyst. The reaction is called Friedel–Crafts alkylation. In Step 1, the alkyl halide coordinates to the Al atom of ${\text{AlCl}}_{\text{3}}$. In Step 2, the 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. If the carbocation intermediate is achiral, the product of the reaction is a racemic mixture, and it will not be optically active.