Question

Assertion: Benzene reacts with iodine monochloride in presence of anhydrous $AlC{{l}_{3}}$ to form iodobenzene.
Reason: Iodine monochloride reacts with anhydrous $AlC{{l}_{3}}$ to produce ${{I}^{+}}$ which attacks the benzene ring.
A. Both assertion and reason are correct and reason are the correct explanation for assertion
B. Both assertion and reason are correct but reason is not the correct explanation of assertion
C. Assertion is correct but reason is incorrect
D. Both assertion and reason are incorrect

Answer 1

In Lewis theory of acid and base reaction, Lewis has given the definition of Lewis acid. Lewis acid is defined as a substance that has the ability to accept non bonding electrons. It is also known as electron pair acceptor. The example of Lewis acid is ${{H}^{+}}$ion.

Complete step-by-step answer: Anhydrous aluminium chloride is strong Lewis acid which is mainly used as a catalyst for halogenation reactions of aromatic ring and friedel crafts alkylation reaction and acylation reaction.
The anhydrous aluminium chloride promotes the chlorination of aromatic molecules.
In the first step the anhydrous aluminium chloride is reacted with iodine monochloride and results in the formation of iodine cation and tetrachloroaluminate.
Let us see the reaction,
$AlC{{l}_{3}}+ICl\to {{I}^{+}}+AlC{{l}_{4}}^{-}$
In the second step, the iodine cation attacks on the benzene ring and results in the formation of iodobenzene and hydrogen ions.
Let us see the reaction,
${{C}_{6}}{{H}_{6}}+{{I}^{+}}\to {{C}_{6}}{{H}_{5}}I+{{H}^{+}}$
In this question, benzene reacts with iodine monochloride in presence of anhydrous aluminium chloride to form iodobenzene. Iodine monochloride reacts with anhydrous aluminium chloride to produce iodine cation which acts as an electrophile and therefore attacks the benzene.
Hence assertion and reason are correct and reason is the correct explanation of assertion.

Therefore option A. is correct.

Note: In this question, we have to note that iodine cation acts as an electrophile. Electrophiles are defined as a species that have the tendency to accept electron pairs and form bonds with nucleophiles. Electrophiles are positively charged whose octet is incomplete. Electrophiles attack mainly nucleophiles through substitution reactions and addition reactions.