Select the number of compounds in which deprotonation gives aromatic anion:

Options

A.
B.
C.
D.

Answer

To solve the question of selecting the number of compounds that give aromatic anions upon deprotonation, we will analyze each of the given options step by step.

### Step 1: Analyze Option A - Barbituric Acid
1. **Structure**: Barbituric acid has two NH groups and multiple carbonyl (C=O) groups.
2. **Deprotonation**: When we remove protons from the NH groups, we can generate negative charges on the nitrogen atoms.
3. **Conjugation**: The negative charge can delocalize through the structure, allowing for resonance stabilization.
4. **Aromaticity**: After deprotonation and resonance, the resulting structure will have a conjugated system with 6 π electrons, satisfying Huckel's rule (4n + 2, where n = 1).
5. **Conclusion**: Barbituric acid can form an aromatic anion upon deprotonation.

### Step 2: Analyze Option B - Ascorbic Acid
1. **Structure**: Ascorbic acid (Vitamin C) contains multiple hydroxyl (OH) groups and a lactone structure.
2. **Deprotonation**: Removing protons from the hydroxyl groups does not lead to a structure that allows for significant conjugation.
3. **Conjugation**: The resulting anion lacks a continuous π system.
4. **Aromaticity**: The structure does not satisfy the criteria for aromaticity and does not have 6 π electrons.
5. **Conclusion**: Ascorbic acid does not form an aromatic anion upon deprotonation.

### Step 3: Analyze Option C
1. **Structure**: This compound has a nitrogen atom and carbonyl groups.
2. **Deprotonation**: Upon removing a proton, a negative charge can be generated.
3. **Conjugation**: The negative charge can delocalize through the nitrogen and carbonyls, creating resonance.
4. **Aromaticity**: The resulting structure has a conjugated system with 6 π electrons, fulfilling Huckel's rule.
5. **Conclusion**: This compound can form an aromatic anion upon deprotonation.

### Step 4: Analyze Option D
1. **Structure**: This compound contains a benzene ring and carbonyl groups.
2. **Deprotonation**: Removing a proton from the hydroxyl group leads to a negative charge.
3. **Conjugation**: The negative charge can delocalize into the benzene ring, creating resonance.
4. **Aromaticity**: The resulting phenoxide ion has 6 π electrons, confirming aromaticity.
5. **Conclusion**: This compound can also form an aromatic anion upon deprotonation.

### Final Conclusion
After analyzing all four options, we find that:
- **Option A**: Aromatic anion (Correct)
- **Option B**: Not aromatic (Incorrect)
- **Option C**: Aromatic anion (Correct)
- **Option D**: Aromatic anion (Correct)

Thus, the total number of compounds that give aromatic anions upon deprotonation is **3** (Options A, C, and D).