Question

Identify the functional groups from the below mentioned options that lead to weakening of benzoic acid:
(A):–OH
(B):–Cl
(C):–NH₂
(D):–NO₂

• A. A and B
• B. A and C
• C. B and C
• D. A and D

Answer 1

The Correct Option is B

To determine which functional groups weaken benzoic acid, we need to understand how these groups influence the electron density of the benzoic acid molecule.

1. Understanding Benzoic Acid:
   • Benzoic acid (C₆H₅COOH) is an aromatic carboxylic acid.
   • The strength of an acid is often influenced by the substituents present on its aromatic ring.
2. Functional Groups Analysis:
   • The acidity of benzoic acid is enhanced by groups that withdraw electrons (electron-withdrawing groups) and is weakened by groups that donate electrons (electron-donating groups).
3. Evaluating the Given Options:
   1. (A) –OH: This is an electron-donating group due to the lone pair on oxygen. It typically increases electron density on the ring, making benzoic acid less acidic.
   2. (B) –Cl: This group is moderately electron-withdrawing due to its electronegativity and resonance effects. It does not typically weaken benzoic acid.
   3. (C) –NH₂: This is a strong electron-donating group due to the lone pair on nitrogen. It decreases the acidity of benzoic acid.
   4. (D) –NO₂: This is a strong electron-withdrawing group and generally increases the acidity of benzoic acid.
4. Conclusion:
   • The functional groups that lead to the weakening of benzoic acid are –OH and –NH₂.
   • The correct answer is A and C.