Which of the following gives aldol condensation reaction ?

Options

A. `C_(6)H_(5)OH`
B. `C_(6)H_(5)-CO-C_(6)H_(5)`
C. 2-Butanone
D. 3,3-dimethyl 2-butanone

Answer

To determine which of the given compounds undergoes aldol condensation, we need to follow these steps:

### Step 1: Understand Aldol Condensation
Aldol condensation is a reaction that occurs between aldehydes or ketones that have at least one alpha-hydrogen in the presence of a dilute alkali base (like sodium hydroxide or potassium hydroxide). The reaction results in the formation of β-hydroxy aldehydes or ketones, which can further dehydrate to give α,β-unsaturated carbonyl compounds.

### Step 2: Identify the Compounds
We have four options to analyze:
1. **C6H5OH** (Phenol)
2. **C6H5** (Benzene)
3. **2-butanone** (CH3COCH2CH3)
4. **3,3-dimethyl-2-butanone** (CH3C(=O)C(CH3)2CH3)

### Step 3: Analyze Each Compound
- **Option 1: C6H5OH (Phenol)**
- Phenol is an alcohol and does not contain an aldehyde or ketone functional group. Therefore, it cannot undergo aldol condensation.

- **Option 2: C6H5 (Benzene)**
- Benzene is a hydrocarbon and does not have a functional group that can participate in aldol condensation. It lacks both carbonyl and alpha-hydrogens. Thus, it cannot undergo aldol condensation.

- **Option 3: 2-butanone (CH3COCH2CH3)**
- 2-butanone has the structure:
```
CH3-CO-CH2-CH3
```
The carbon adjacent to the carbonyl (C=O) has two alpha-hydrogens (the CH2 group). Therefore, it can undergo aldol condensation.

- **Option 4: 3,3-dimethyl-2-butanone (CH3C(=O)C(CH3)2CH3)**
- The structure is:
```
CH3-C(=O)-C(CH3)2-CH3
```
Although it has alpha-hydrogens, steric hindrance due to the bulky methyl groups on the alpha carbon prevents it from undergoing aldol condensation effectively.

### Step 4: Conclusion
Based on the analysis, the only compound that can undergo aldol condensation is **2-butanone** (Option 3).

### Final Answer:
**2-butanone (Option 3) gives aldol condensation reaction.**

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