Question

The carbonyl compound that does not undergo aldol condensation is

• A. Acetone
• B. Di chloro acetaldehyde
• C. Tri chloro acetaldehyde
• D. Acetaldehyde

Answer 1

The Correct Option is C

Aldol condensation is a reaction between two carbonyl compounds (such as aldehydes or ketones) that results in the formation of a β-hydroxy carbonyl compound, which can further undergo dehydration to give an α,β-unsaturated carbonyl compound.

For aldehydes and ketones to undergo aldol condensation, the hydrogen atom at the α-position (adjacent to the carbonyl group) must be sufficiently acidic to be abstracted by a base.

In the case of dichloroacetaldehyde (option C), the presence of two electronegative chlorine atoms attached to the α-carbon significantly reduces the acidity of the α-hydrogens, making them less available for abstraction. This prevents the reaction from proceeding effectively, so dichloroacetaldehyde does not undergo aldol condensation.

Therefore, the correct answer is (C): dichloroacetaldehyde. 

Answer 2

Aldol condensation is a reaction where the enolate ion of one carbonyl compound attacks the carbonyl carbon of another, forming a $\beta$-hydroxy carbonyl compound (aldol). The reaction typically occurs when there is a hydrogen atom adjacent to the carbonyl group. However, compounds with electron-withdrawing groups (such as halogens) in the $\alpha$-position (next to the carbonyl group) can inhibit the formation of the enolate ion and prevent aldol condensation.

In the case of dichloroacetaldehyde, the two chlorine atoms in the $\alpha$-position are strong electron-withdrawing groups, which make it difficult for the compound to form the enolate ion necessary for the aldol condensation reaction.

Thus, dichloroacetaldehyde does not undergo aldol condensation, while acetaldehyde, acetone, and trichloroacetaldehyde can undergo aldol condensation.

Therefore, the correct answer is dichloroacetaldehyde.