Question

Which from following compounds is obtained when phenol reacts with dilute nitric acid at low temperature?

• A. o-Nitrophenol only
• B. p-Nitrophenol only
• C. 2, 4, 6-trinitrophenol
• D. Mixture of ortho and para nitrophenols

Hint:

Phenol + Dilute $\text{HNO}_3 \rightarrow$ Ortho and Para isomers (Mononitration).
Phenol + Conc. $\text{HNO}_3 + \text{H}_2\text{SO}_4 \rightarrow$ Picric Acid (2,4,6-Trinitrophenol).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Phenol is highly reactive towards electrophilic aromatic substitution because the $-OH$ group is strongly activating and ortho/para directing.

Step 2: Formula Application:
Nitration of phenol depends on the concentration of $HNO_3$: 1. Dilute $HNO_3$ (Low Temp) $\to$ Mononitration. 2. Conc. $HNO_3$ $\to$ Trinitration ($2,4,6$-trinitrophenol).

Step 3: Explanation:
With dilute nitric acid at 298 K, phenol yields a mixture of ortho and para nitrophenols. The ortho isomer is usually formed in higher amounts due to the statistical advantage of two ortho positions, but the para isomer is often easier to separate.

Step 4: Final Answer:
A mixture of ortho and para nitrophenols is obtained.