Question

Identify the product (A) obtained in the following reaction.
$\text{Phenol} + \text{concentrated Nitric acid} \xrightarrow{\text{concentrated } \mathrm{H_2SO_4}} \text{A}$

• A. o-Nitrophenol
• B. p-Nitrophenol
• C. mixture of o-Nitrophenol and p-Nitrophenol
• D. 2, 4, 6-Trinitrophenol

Hint:

Remember this crucial reagent distinction for phenol nitration: 1. $\text{Dilute } \mathrm{HNO_3} \rightarrow \text{Mono-substitution (ortho + para mixture)}.$ 2. $\text{Concentrated } \mathrm{HNO_3} + \text{conc. } \mathrm{H_2SO_4} \rightarrow \text{Tri-substitution (Picric acid)}.$

Answer 1

The Correct Option is D

Step 1: Note the reagents carefully.
Phenol is treated with concentrated $HNO_3$ together with concentrated $H_2SO_4$. The word concentrated for both is the key signal.
Step 2: Recall the directing power of $-OH$.
The hydroxyl group strongly activates the ring and directs incoming groups to the ortho ($2,6$) and para ($4$) positions.
Step 3: Link concentration to extent of reaction.
Dilute nitric acid gives only a single nitro group and stops at a mono product, but a strong concentrated mixture keeps substituting at every activated site.
Step 4: Place the nitro groups.
With the powerful mixture, $NO_2^+$ enters both ortho positions ($2$ and $6$) and the para position ($4$), filling all three activated carbons.
Step 5: Write the balanced change.
\[ C_6H_5OH + 3HNO_3 \xrightarrow{conc.\ H_2SO_4} C_6H_2(NO_2)_3OH + 3H_2O \]
Step 6: Name the product.
Three nitro groups at $2,4,6$ on phenol give $2,4,6$ trinitrophenol, the well known picric acid.
\[ \boxed{2,4,6\text{ Trinitrophenol (option D)}} \]