Question

Give the possible structure of X in the following reaction: C₆H₆ + D₂SO₄ xrightarrowD₂O X 

• A. \(\mathrm{C_6H_5SO_3D}\)
• B. \(\mathrm{C_6H_4DSO_3D}\)
• C. \(\mathrm{C_6H_4DSO_3H}\)
• D. C₆D₆

Hint:

• Sulfonation of benzene is reversible • In D₂SO₄/D₂O, repeated sulfonation–desulfonation causes full H/D exchange

Answer 1

The Correct Option is D

Step 1: Benzene reacts with D₂SO₄ to undergo sulfonation, forming benzene sulfonic acid with SO₃D group.
Step 2: In the presence of D₂O, desulfonation occurs along with H/D exchange on the benzene ring.
Step 3: Under these strongly acidic conditions, repeated sulfonation–desulfonation leads to complete replacement of all ring hydrogens by deuterium. ⟹ X = C₆D₆