Which of the following on heating with aqueous `KOH` produces acetaldehyde?

Options

A. `CH_(2)ClCH_(2)Cl`
B. `CH_(3)CHCl_(2)`
C. `CH_(3)COCl`
D. `CH_(3)CH_(2)Cl`

Answer

To determine which compound produces acetaldehyde upon heating with aqueous KOH, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have four compounds to consider:
- Option 1: CH₂CH₂Cl₂
- Option 2: CH₃CHClCl
- Option 3: CH₃COCl
- Option 4: CH₃CH₂Cl

2. **Analyze Option 1 (CH₂CH₂Cl₂)**:
- When CH₂CH₂Cl₂ is treated with aqueous KOH, the chlorine atoms act as leaving groups.
- The reaction leads to the formation of a glycol (diol) rather than acetaldehyde.
- **Conclusion**: This option does not produce acetaldehyde.

3. **Analyze Option 2 (CH₃CHClCl)**:
- Upon reaction with aqueous KOH, the two chlorine atoms leave, and two hydroxyl (OH) groups are added to the same carbon.
- This results in an unstable intermediate that undergoes dehydration (loss of water) to form acetaldehyde (CH₃CHO).
- **Conclusion**: This option produces acetaldehyde.

4. **Analyze Option 3 (CH₃COCl)**:
- When CH₃COCl reacts with aqueous KOH, the chlorine atom is a better leaving group, leading to the formation of acetic acid (CH₃COOH).
- **Conclusion**: This option does not produce acetaldehyde.

5. **Analyze Option 4 (CH₃CH₂Cl)**:
- The reaction of CH₃CH₂Cl with aqueous KOH results in the formation of an alcohol (ethanol) rather than acetaldehyde.
- **Conclusion**: This option does not produce acetaldehyde.

### Final Conclusion:
The only compound that produces acetaldehyde when heated with aqueous KOH is **Option 2: CH₃CHClCl**.