Aldol condensation will not be observed in

Options

A. Chloral
B. Phenyl acetaldehyde
C. Hexanal
D. Ethanal

Answer

To determine in which compound aldol condensation will not be observed, we need to understand the requirements for this reaction. Aldol condensation requires the presence of alpha hydrogen atoms (alpha H) on the carbon adjacent to the carbonyl group. Here’s a step-by-step solution to the question:

### Step-by-Step Solution:

1. **Understanding Aldol Condensation**:
- Aldol condensation is a reaction where an enolate ion reacts with a carbonyl compound in the presence of a base, leading to the formation of a β-hydroxy aldehyde or ketone, which can further dehydrate to form an α,β-unsaturated carbonyl compound.

2. **Identifying the Role of Alpha Hydrogen**:
- The enolate ion, which is crucial for aldol condensation, is formed from the abstraction of an alpha hydrogen (H) from the alpha carbon (the carbon adjacent to the carbonyl group). Therefore, the presence of alpha hydrogens is essential for the reaction to occur.

3. **Analyzing the Given Compounds**:
- We need to check the structures of the compounds provided to see if they contain alpha hydrogen atoms.

4. **Compound Analysis**:
- **Chloral (Trichloroacetaldehyde)**:
- Structure: CCl3CHO
- Analysis: The carbon adjacent to the carbonyl group (alpha carbon) has no hydrogen atoms because it is substituted with three chlorine atoms. Therefore, chloral does not have any alpha H and will not undergo aldol condensation.

- **Phenyl Acetate**:
- Structure: C6H5OCOCH3
- Analysis: The alpha carbon has two hydrogen atoms (CH2), so aldol condensation is possible.

- **Hexanal**:
- Structure: CH3(CH2)4CHO
- Analysis: The alpha carbon has two hydrogen atoms (CH2), so aldol condensation is possible.

- **Ethanol**:
- Structure: CH3CH2OH
- Analysis: The alpha carbon has three hydrogen atoms (CH3), so aldol condensation is possible.

5. **Conclusion**:
- Based on the analysis, the compound that will not undergo aldol condensation is **Chloral (Trichloroacetaldehyde)**, as it lacks alpha hydrogen atoms.

### Final Answer:
Aldol condensation will not be observed in **Chloral (Trichloroacetaldehyde)**.