Which of the following undergoes aldol condensation?

Options

A. Acetaldehyde
B. Propionaldehyde
C. Benzaldehyde
D. Trideuteroacetaldehyde

Answer

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

### Step-by-Step Solution

1. **Understand Aldol Condensation**: Aldol condensation is a reaction between carbonyl compounds (aldehydes or ketones) that have at least one alpha hydrogen. The reaction involves the formation of an enolate ion from one carbonyl compound, which then attacks another carbonyl compound to form a beta-hydroxy carbonyl compound.

2. **Identify the Requirements**: For a compound to undergo aldol condensation, it must have:
- A carbonyl group (C=O).
- At least one alpha hydrogen attached to the carbon adjacent to the carbonyl carbon.

3. **Analyze Each Compound**:
- **Compound 1: Acetaldehyde (CH3CHO)**:
- Structure: CH3- (alpha carbon) has 3 alpha hydrogens.
- Conclusion: Yes, it can undergo aldol condensation.

- **Compound 2: Propionaldehyde (CH3CH2CHO)**:
- Structure: CH3-CH2- (alpha carbon) has 2 alpha hydrogens.
- Conclusion: Yes, it can undergo aldol condensation.

- **Compound 3: Benzaldehyde (C6H5CHO)**:
- Structure: The carbon adjacent to the carbonyl (alpha carbon) is connected to a benzene ring and has no hydrogen.
- Conclusion: No, it cannot undergo aldol condensation.

- **Compound 4: Trideuterated Acetaldehyde (CD3CHO)**:
- Structure: CD3- (alpha carbon) has 3 deuterated alpha hydrogens (isotope of hydrogen).
- Conclusion: Yes, it can undergo aldol condensation.

4. **Final Conclusion**: The compounds that can undergo aldol condensation are:
- Acetaldehyde (Compound 1)
- Propionaldehyde (Compound 2)
- Trideuterated Acetaldehyde (Compound 4)

### Summary of Results
- **Compounds that undergo aldol condensation**:
- Acetaldehyde (1)
- Propionaldehyde (2)
- Trideuterated Acetaldehyde (4)