Phenol, when it first reacts with concentrated sulphuric acid and then with concentrated nitric acid, gives

Options

A. nitrobenzene
B. 2,4,6-trinitrobenzene
C. o-nitrophenol
D. p-nitrophenol

Explanation

To solve the problem, we need to analyze the reactions of phenol with concentrated sulfuric acid followed by concentrated nitric acid step by step.

### Step 1: Reaction of Phenol with Concentrated Sulfuric Acid
When phenol (C6H5OH) reacts with concentrated sulfuric acid (H2SO4), it undergoes sulfonation. The hydroxyl group (-OH) of phenol is replaced by a sulfonyl group (-SO3H). This reaction primarily occurs at the ortho and para positions relative to the hydroxyl group due to the activating nature of the -OH group.

**Reaction:**
\[ \text{C}_6\text{H}_5\text{OH} + \text{H}_2\text{SO}_4 \rightarrow \text{C}_6\text{H}_4\text{(SO}_3\text{H)} + \text{H}_2\text{O} \]
This results in the formation of phenol sulfonic acid (C6H4(SO3H)).

### Step 2: Reaction of Sulfonated Phenol with Concentrated Nitric Acid
Next, the sulfonated phenol reacts with concentrated nitric acid (HNO3). The sulfonyl group (-SO3H) is a good leaving group, which allows the nitronium ion (NO2+) from nitric acid to attack the aromatic ring. The electrophilic substitution can occur at the ortho and para positions relative to the -SO3H group.

Given that the -SO3H group is already present, the nitro group can be added to the ortho or para positions of the aromatic ring.

**Possible Products:**
1. Ortho-nitrophenol sulfonic acid
2. Para-nitrophenol sulfonic acid

However, since the -SO3H group is already at the para position, the nitro group will predominantly attach to the ortho position, leading to the formation of ortho-nitrophenol sulfonic acid.

### Final Products
The final products of the reaction sequence are:
- Ortho-nitrophenol sulfonic acid (C6H4(NO2)(SO3H))
- Para-nitrophenol sulfonic acid (C6H4(NO2)(SO3H))

### Conclusion
The main products formed when phenol reacts first with concentrated sulfuric acid and then with concentrated nitric acid are ortho-nitrophenol and para-nitrophenol, with the para-nitrophenol being the major product.