Which of the following compound gives pink colour on reaction with pthalic anhydride in conc. `H_2SO_4` followed by reatment with NaOH?

Options

A.
B.
C.
D.

Answer

To determine which compound gives a pink color upon reaction with phthalic anhydride in concentrated sulfuric acid followed by treatment with sodium hydroxide, we can follow these steps:

### Step 1: Understand the Reaction
Phthalic anhydride reacts with certain compounds (usually those containing hydroxyl or amino groups) in the presence of concentrated sulfuric acid to form a colored complex. The reaction typically involves the formation of a dye-like structure.

### Step 2: Identify the Compounds
We need to analyze the given options to identify which compound contains a hydroxyl (-OH) or amino (-NH2) group that can react with phthalic anhydride.

### Step 3: Reaction with Phthalic Anhydride
When phthalic anhydride reacts with a compound containing an -OH group, it forms an intermediate complex. This complex can then undergo further reactions that may lead to the formation of a colored product.

### Step 4: Treatment with Sodium Hydroxide
After the initial reaction with phthalic anhydride, the addition of sodium hydroxide can lead to hydrolysis or further reactions that stabilize the colored complex, resulting in a pink color.

### Step 5: Analyze the Options
- **Option 1**: If this compound contains an -OH group, it is likely to form the pink complex.
- **Option 2, 3, 4**: If these compounds do not contain -OH or -NH2 groups, they will not give the pink color.

### Step 6: Conclusion
Based on the analysis, the compound that gives a pink color upon reaction with phthalic anhydride in concentrated sulfuric acid followed by treatment with sodium hydroxide is **Option 1**.