Which of the following compound does undergo aldol condensation

Options

A. HCHO
B. `CH_3-underset(CH_3)underset(|)overset(CH_3)overset(|)C-CHO`
C. `"CCl"._3 CHO`
D. `CH_3.CH_2.CHO`

Answer

To determine which compound undergoes aldol condensation, we need to identify compounds that contain alpha hydrogen atoms and can react in the presence of a dilute alkali. Here’s a step-by-step solution:

### Step 1: Understand Aldol Condensation
Aldol condensation involves the reaction of two molecules of aldehyde or ketone that have at least one alpha hydrogen atom. In the presence of a dilute base (like sodium hydroxide), these compounds can undergo a condensation reaction to form a beta-hydroxy aldehyde or ketone.

**Hint:** Remember that only compounds with alpha hydrogen atoms can participate in aldol condensation.

### Step 2: Analyze Each Compound
1. **Formaldehyde (HCHO)**:
- Structure: HCHO has no alpha carbon because it is the simplest aldehyde.
- Conclusion: No alpha hydrogen present, so it cannot undergo aldol condensation.

**Hint:** Check for the presence of alpha hydrogen by identifying the carbon adjacent to the carbonyl group.

2. **Acetaldehyde (CH3CHO)**:
- Structure: CH3CHO has an alpha carbon (the carbon next to the carbonyl) with three hydrogen atoms.
- Conclusion: It can undergo aldol condensation.

**Hint:** Look for the carbon adjacent to the carbonyl and count the hydrogen atoms attached.

3. **Propionaldehyde (C2H5CHO)**:
- Structure: C2H5CHO has an alpha carbon with two hydrogen atoms.
- Conclusion: It can undergo aldol condensation.

**Hint:** Identify the alpha carbon and ensure it has at least one hydrogen.

4. **Butyraldehyde (C3H7CHO)**:
- Structure: C3H7CHO has an alpha carbon with two hydrogen atoms.
- Conclusion: It can undergo aldol condensation.

**Hint:** Similar to previous steps, check the alpha carbon for hydrogen atoms.

### Step 3: Identify the Correct Answer
From the analysis:
- Formaldehyde does not undergo aldol condensation.
- Acetaldehyde, Propionaldehyde, and Butyraldehyde can undergo aldol condensation.

Thus, the correct answer is **Acetaldehyde (CH3CHO)**, as it is the compound that undergoes aldol condensation.

**Final Conclusion:** The compound that undergoes aldol condensation is **Acetaldehyde (CH3CHO)**.