Phenol + Phthalic anhydride `overset("Conc."H_(2)SO_(4))underset("fusion")(to)B`. B gives which of following colour in alkaline medium.

Options

A. Yellow
B. Colourless
C. Pink
D. Violet

Answer

To solve the question step by step, we will analyze the reaction between phenol and phthalic anhydride, and then determine the color of the resulting compound in an alkaline medium.

### Step 1: Identify the Reactants
- The reactants in this reaction are **phenol** and **phthalic anhydride**.

### Step 2: Reaction Conditions
- The reaction occurs in the presence of **concentrated sulfuric acid (H₂SO₄)**, which acts as a catalyst.

### Step 3: Reaction Mechanism
- When phenol reacts with phthalic anhydride under these conditions, it undergoes a condensation reaction to form a compound known as **phenolphthalein** (denoted as B).

### Step 4: Structure of the Product
- The structure of phenolphthalein can be represented as follows:
- It consists of two phenolic groups linked by a carbonyl group, which is characteristic of phenolphthalein.

### Step 5: Behavior in Different Mediums
- Once phenolphthalein is formed, we need to consider its behavior in different pH conditions:
- In **acidic medium**, phenolphthalein is **colorless**.
- In **alkaline medium**, phenolphthalein exhibits a **pink color**.

### Step 6: Conclusion
- The question specifically asks for the color of compound B (phenolphthalein) in alkaline medium. Based on our analysis, the answer is that phenolphthalein gives a **pink color** in alkaline medium.

### Final Answer
- The correct answer is **pink**.

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