Aldol condensation will not take place in

Options

A. `CH_(3)CHO`
B. `CH_(3)COCH_(3)`
C. `HCHO`
D. `CH_(3)CH_(2)CHO`

Answer

To solve the question regarding which compound will not undergo aldol condensation, we need to understand the requirements for this reaction. Aldol condensation typically occurs between aldehydes or ketones that possess at least one alpha hydrogen atom.

### Step-by-Step Solution:

1. **Understanding Aldol Condensation**:
- Aldol condensation is a reaction between aldehydes or ketones that have at least one alpha hydrogen atom. The presence of this hydrogen is crucial because it allows for the formation of an enolate ion, which is necessary for the condensation reaction to occur.

2. **Analyzing the Options**:
- We need to evaluate each option to identify which one does not have an alpha hydrogen.

3. **Option 1**:
- Let's assume this option is an aldehyde (e.g., CH3CHO).
- Aldehydes typically have alpha hydrogens. Therefore, this option will undergo aldol condensation.

4. **Option 2**:
- Assume this is a ketone (e.g., CH3COCH3).
- Ketones also have alpha hydrogens (the two CH3 groups). Thus, this option will also undergo aldol condensation.

5. **Option 3**:
- Assume this is formaldehyde (HCHO).
- Formaldehyde has no alpha hydrogens because it has only one carbon atom and its structure is H2C=O. Therefore, it cannot undergo aldol condensation.

6. **Option 4**:
- Assume this is an aldehyde with a longer carbon chain (e.g., CH3CH2CHO).
- This compound has alpha hydrogens and will also undergo aldol condensation.

7. **Conclusion**:
- The only compound that does not have an alpha hydrogen and therefore cannot undergo aldol condensation is **Option 3 (HCHO)**.

### Final Answer:
**Aldol condensation will not take place in HCHO (formaldehyde).**