Question

Lewis acid other than anhydrous aluminium chloride which can be used during ethylation of benzene is:
A. $FeC{{l}_{3}}$
B. $KOH$
C. $LiAl{{H}_{4}}$
D. None of these

Answer 1

We know that the ethylation reaction of benzene involves the addition of an ethyl group on the benzene ring. Such a reaction is called a Friedel-Craft alkylation reaction. Lewis acid other than anhydrous aluminium chloride which can be used during ethylation of benzene is ferric chloride $FeC{{l}_{3}}$.

Complete step by step solution:
Potassium hydroxide can’t be used as it is a base. Also lithium aluminium hydride can’t be used as it is a strong reducing agent. Generally ethylation is carried out by the Friedel craft alkylation through the formation of sigma structure and the removal of hydrogen ion at last. Presence of a good Lewis acid increases the rate of the reaction.
So it’s necessary to have a good Lewis acid for having good yield of ethylbenzene. Such a reaction is called a Friedel-Craft alkylation reaction. This reaction takes place in the presence of a Lewis acid. Any Lewis acid like anhydrous ferric chloride, stannous chloride, boron trifluoride etc. can be used during the ethylation of benzene.
The ethylation reaction of benzene involves the addition of an ethyl group on the benzene ring. Such a reaction is called a Friedel-Craft alkylation reaction. This reaction takes place in the presence of a Lewis acid. Any Lewis acid like anhydrous $FeC{{l}_{3}},SnC{{l}_{4}},B{{F}_{3}}$ etc. can be used during the ethylation of benzene

So, the correct answer is Option A

Note: Note that the Lewis acid used here is the strong Lewis acid which forms a complex and retains its property. The ethylation reaction of benzene involves the addition of an ethyl group on the benzene ring.