Chapter 19.2, Problem 1CC

Interpretation Introduction

Interpretation:

The mechanism for the reaction between Benzene and ${\text{I}}^{\text{+}}$ in Iodination of Benzene by ${\text{I}}_{\text{2}}{\text{/CuCl}}_{\text{2}}$ has to be depicted.

Concept Introduction:

Electrophilic substitution reaction is a type of reaction in which a particular group or atom in a compound is replaced by electrophile. An electrophile is a species that is deficient of electrons.

Aromaticity is the property of organic compounds having cyclic and planar structure with $\left(\text{4n+2}\right)\text{π}$ electrons. It attributes to the stability of the compound. A compound that is aromatic is said to be highly stable.

Being an electron rich Aromatic compound, Benzene undergoes electrophilic substitution reaction.

Benzene with positive charge on one of its Carbon atom is known as arenium carbocation.

The delocalizing pi electrons neutralize the positive charge and in the process positive charge forms again. The process of formation of carbocation and neutralizing the positive charge simultaneously occurs. The phenomenon of stabilizing and sustaining the positive charge on the benzene by delocalizing electrons is known as “resonance”.

Benzene undergoes electrophilic substitution reaction when treated with Iodine and ${\text{CuCl}}_{\text{2}}$. In this reaction ${\text{I}}^{\text{+}}$ ion acts as electrophile. The electron density that is pi – electron cloud of benzene exerts attraction towards the positive ${\text{I}}^{\text{+}}$ ion. As a result the reaction is initiated and eventually ${\text{I}}^{\text{+}}$ replaced one of the six Hydrogen atoms of benzene. The product formed is Iodobenzene which is known as “substituted product”.