Which of the following do not give aldol reaction with dil. NaOH

Options

A. `CH_(3)CHO`
B. `CD_(3)CHO`
C. `CH_(3)COCH_(3)`
D. PhCHO

Answer

To determine which of the given compounds does not undergo aldol reaction with dilute sodium hydroxide (NaOH), we need to analyze each compound for the presence of alpha hydrogen atoms. Aldol reactions occur when carbonyl compounds have alpha hydrogens available for reaction.

### Step-by-Step Solution:

1. **Understand Aldol Reaction**:
- Aldol condensation is a reaction between carbonyl compounds (aldehydes or ketones) that have alpha hydrogen atoms. The reaction occurs in the presence of a base, such as dilute NaOH.

2. **Identify Alpha Hydrogen**:
- Alpha hydrogen is the hydrogen atom attached to the carbon atom adjacent to the carbonyl group (C=O). If a carbonyl compound has alpha hydrogens, it can participate in aldol condensation.

3. **Analyze Each Compound**:
- **Compound 1: Acetaldehyde (CH3CHO)**
- Structure: CH3-C(=O)H
- Alpha Carbon: The carbon next to the carbonyl (C=O) has three hydrogen atoms (alpha hydrogens).
- Conclusion: Acetaldehyde can undergo aldol reaction.

- **Compound 2: Deuterated Acetaldehyde (CD3CHO)**
- Structure: CD3-C(=O)H
- Alpha Carbon: The carbon next to the carbonyl has three deuterium atoms (isotope of hydrogen).
- Conclusion: Deuterated acetaldehyde can undergo aldol reaction.

- **Compound 3: Acetone (CH3COCH3)**
- Structure: CH3-C(=O)-CH3
- Alpha Carbons: There are two alpha carbons, each with three hydrogen atoms (total of six alpha hydrogens).
- Conclusion: Acetone can undergo aldol reaction.

- **Compound 4: Benzaldehyde (C6H5CHO)**
- Structure: C6H5-C(=O)H
- Alpha Carbon: The carbon next to the carbonyl is part of the phenyl ring and does not have any hydrogen atoms (due to resonance and the nature of the benzene ring).
- Conclusion: Benzaldehyde does not have alpha hydrogens and therefore cannot undergo aldol reaction.

4. **Final Conclusion**:
- The compound that does not undergo aldol reaction with dilute NaOH is **Benzaldehyde (Option D)**.

### Final Answer:
**Option D: Benzaldehyde does not give aldol reaction with dilute NaOH.**