Arrange the following compounds in increasing order of their acidic character.
(A) m-nitrophenol
(B) p-nitrophenol
(C) Phenol
(D) p-methoxyphenol
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (D), (C), (A), (B)
Acidity of phenols depends on the electron-withdrawing or electron-donating groups attached to the ring:
- EWGs (–NO₂) increase acidity by stabilizing the phenoxide ion.
- EDGs (–OCH₃) decrease acidity by destabilizing the phenoxide ion.
- Position of substituent matters: ortho > para > meta for –NO₂ due to resonance and inductive effects.
Given compounds:
- D: p-methoxyphenol → EDG → least acidic
- C: Phenol → neutral → more acidic than D
- A: m-nitrophenol → meta NO₂ → more acidic than C
- B: p-nitrophenol → para NO₂ → most acidic (resonance stabilization)
Increasing order of acidity:
$\text{D} < \text{C} < \text{A} < \text{B}$