Chapter 18.5, Problem 6CC

Interpretation Introduction

Interpretation:

The mechanism for the following reaction has to be illustrated –

                          

Concept Introduction:

• Electrophilic substitution reactions of aromatic compounds are known as aromatic electrophilic substitution reactions. An electrophile is a species that is deficient of electrons.

• Friedel Crafts reaction is an electrophilic substitution reaction. This reaction involves $\text{C-C}$ bond formation between benzene Carbon and any other alkyl or aryl or acyl carbon. Thus this reaction is constructive to insert alkyl, aryl or acyl group onto benzene ring. So this reaction is commonly known as Friedel Crafts acylation if acyl group is inserted on benzene ring or Friedel Crafts alkylation if alkyl group is inserted on benzene ring.

• Any of Lewis acids such as ${\text{AlCl}}_{\text{3,}}{\text{FeCl}}_{\text{3}}\text{,}{\text{BF}}_{\text{3}}\text{etc}$ is required to initiate the reaction. The Lewis acid act as catalyst assists in the formation of electrophile.  The reaction between Alkyl halide and Lewis acid generates alkyl carbocation. The alkyl carbocation serves as electrophile in Friedel Crafts alkylation.