Question

Assertion: Alkylbenzene is not prepared by Friedel-Crafts alkylation of benzene.
Reason: Alkyl halides are less reactive than acyl halides.
Read the above assertion and reason and choose the correct option regarding it.
A.Both assertion and reason are correct and the reason is the correct explanation for assertion.
B.Both assertion and reason are correct and the reason is not the correct explanation for assertion.
C.The assertion is correct but the reason is incorrect.
D.Both assertion and reason are incorrect.

Answer 1

Before answering this question, we should first know about Friedel-Crafts reaction. An organic coupling reaction that includes an electrophilic aromatic substitution that is important for the joining of substituents to aromatic rings is called the Friedel-Crafts reaction.

Complete answer:
There are two types of Friedel-Crafts reaction which are alkylation and acylation. Charles Friedel and James Craft developed these reactions in 1877. Here, both of the reactions face substitution of the Hydrogen atom (linked to the aromatic ring) with an electrophile. The catalyst used in the Friedel-crafts reaction is Aluminium trichloride as it acts as a Lewis base and works with halogens in order to create electrophile in the reaction.
BENZENE: A ring that has six carbon atoms that are bonded by single and double bonds arranged alternatively. The molecular formula of it is ${{C}_{6}}{{H}_{6}}$
Assertion: Alkylbenzene is not prepared by Friedel-Crafts Alkylation of benzene
The monoalkyl derivative that is first formed readily undergoes further alkylation fast in order to prepare polysubstituted products and isomeric change may occur to alkyl halide and separation of the products is not easy. Due to these obstacles, Friedel-Crafts alkylation of benzene does not prepare alkyl benzene.
Reason: Alkyl halides are less reactive than acyl halides
The C atoms of alkyl halides are less electrophilic than the C atom of carbonyl. So, Alkyl halides are less reactive than acyl halides.

So, Option (B) Both assertion and reason are correct but the reason is not the correct explanation for the assertion is correct.

Note:
Limitation of Friedel-Crafts alkylation are-
Not all alkylbenzene can be formed because of the ability of cation to be rearranged.
Nitrobenzene and strong deactivating systems cannot be formed through this reaction.
The products of Friedel-Crafts are more reactive than the initiating material.