When phenol reacts with phtalic anhydride in presence of `H_2SO_4 ` and heated and hot reaction mixture is poured in ` NaOH` solution. The product formed is

Options

A. alizarin
B. methyl orange
C. fluorescein
D. phenolphthalein .

Explanation

To solve the problem, we need to analyze the reaction between phenol and phthalic anhydride in the presence of concentrated sulfuric acid (H₂SO₄) and understand the product formed after pouring the hot reaction mixture into NaOH solution.

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants are phenol (C₆H₅OH) and phthalic anhydride (C₈H₄O₃).

2. **Reaction Conditions**:
- The reaction takes place in the presence of concentrated sulfuric acid (H₂SO₄), which acts as a dehydrating agent.

3. **Mechanism of Reaction**:
- When phenol reacts with phthalic anhydride in the presence of H₂SO₄, a coupling reaction occurs. The hydroxyl group (–OH) of phenol can attack the carbonyl carbon of phthalic anhydride, leading to the formation of a new compound.
- During this reaction, water (H₂O) is eliminated (dehydration), resulting in the formation of a compound that contains two phenolic units linked by a carbonyl group.

4. **Formation of Phenolphthalein**:
- The product formed from this reaction is phenolphthalein, which has the structure:
- Two phenolic rings connected by a carbonyl (C=O) and an ether-like linkage (C–O–C).
- The structure can be represented as:
```
C6H4(OH) - C(=O) - O - C(=O) - C6H4(OH)
```

5. **Pouring into NaOH Solution**:
- After the reaction, when the hot mixture is poured into NaOH solution, it helps to neutralize the acid and stabilize the product. However, the main product remains phenolphthalein.

6. **Final Product**:
- The final product formed after the reaction is phenolphthalein.

### Conclusion:
The product formed when phenol reacts with phthalic anhydride in the presence of H₂SO₄ and is then poured into NaOH solution is **phenolphthalein**.

### Answer:
**Phenolphthalein**