Question

Assertion (A) : Aromatic carboxylic acids do not undergo Friedel-Crafts reaction.

Reason (R) : Carboxyl group is deactivating and the catalyst aluminium chloride gets bonded to carboxyl group.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

The -COOH group deactivates the ring and also binds the AlCl3 catalyst, so both statements are true and R explains A.

Answer 1

The Correct Option is A

Step 1: Recall the reaction:
Friedel-Crafts alkylation and acylation are electrophilic substitution reactions.
They need an electron-rich benzene ring and a Lewis acid catalyst such as anhydrous \( \mathrm{AlCl_3} \).

Step 2: Check the Assertion:
Benzoic acid and other aromatic carboxylic acids do not give Friedel-Crafts reactions.
So Assertion (A) is true.

Step 3: Check the Reason:
The -COOH group pulls electrons from the ring, so it is a deactivating group.
It makes the ring poor in electrons and slows electrophilic attack.
The oxygen atoms of -COOH also have lone pairs. They bind to \( \mathrm{AlCl_3} \) and the catalyst is lost.
So Reason (R) is true.

Step 4: Relate R to A:
Both effects, the deactivated ring and the loss of catalyst, stop the reaction.
So R is the correct explanation of A.

Final Answer:
Both are true and R explains A, option (A). \[ \boxed{\text{(A)}} \]