Toluene reacts with a halogen in the presence of \( FeCl_3 \), giving a mixture of ortho and para halo compounds. This type of reaction is called
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Electrophilic substitution reaction
A benzene ring is rich in \(\pi\) electrons, so it is attacked by electrophiles, and it keeps its aromatic ring by losing \( \ce{H^+} \): the electrophile substitutes a hydrogen atom. Halogen molecules are not strong enough electrophiles by themselves. The Lewis acid \( \ce{FeCl3} \) polarises the halogen and generates the electrophile:
\( \displaystyle \ce{Cl2 + FeCl3 -> Cl^+ + [FeCl4]^-} \)
The methyl group of toluene donates electrons to the ring and directs the electrophile to the ortho and para positions, so a mixture of the two isomers is formed:
\( \displaystyle \ce{C6H5CH3 + Cl2} \xrightarrow{\ce{FeCl3}} o\text{-}\ce{ClC6H4CH3} + p\text{-}\ce{ClC6H4CH3} + \ce{HCl} \)
So the reaction is an electrophilic substitution reaction.
Why the other options are incorrect
Option (1) Nucleophilic substitution reaction — Incorrect. In this the leaving group is replaced by an electron-rich nucleophile, as in the hydrolysis of an alkyl halide by \( \ce{OH^-} \); the electron-rich ring of toluene is not attacked by nucleophiles.
Option (3) Free radical addition reaction — Incorrect. Nothing is added across a double bond here; the ring keeps its aromatic character. (In sunlight and without a catalyst, chlorine attacks the methyl group of toluene by a free radical substitution, giving benzyl chloride.)
Option (4) Nucleophilic addition reaction — Incorrect. This is the typical reaction of the C=O group of aldehydes and ketones, not of an aromatic ring.
NCERT (2026-27 edition):
From Hydrocarbons by Electrophilic Substitution
