Reaction mechanism of desulphonation of benzene ring using dil. #"HCl"# and, #"H"_2"SO"_4//150^@c# "?"

1 Answer
Jun 7, 2018

Answer:

Here's what I get.

Explanation:

The sulfonation of benzene is a reversible reaction.

Sulfonation

Thus, we can remove a sulfonic acid group by heating the compound with an acid.

The reaction with steam alone is often sufficient for desulfonation.

The mechanism of desulfonation

Step 1. Attack by an electrophile

Protonation

A hydronium ion protonates the aromatic ring and generates a resonance-stabilized carbocation intermediate.

Step 2. Desulfonation

Desulfonation

A base deprotonates the sulfonic acid, and the sulfur trioxide leaves, regenerating the aromatic ring.