What combination of compounds typically undergoes aldol condensation?

• A. Aldehyde + Aldehyde
• B. Ketone + Ketone
• C. Aldehyde + Ketone
• D. All of the above

Answer: (D)

Aldol condensation is a reaction that occurs when two carbonyl compounds, such as aldehydes or ketones, react in the presence of a base to form a β-hydroxy aldehyde or ketone, which can then dehydrate to yield an α,β-unsaturated carbonyl compound.

The process begins with the enolate ion formation from one carbonyl compound when a base abstracts a proton from the α-carbon. This enolate ion then acts as a nucleophile and attacks another carbonyl carbon from either another aldehyde or ketone, leading to the formation of a β-hydroxy carbonyl compound.

Each of the mentioned pairs—aldehyde with aldehyde, ketone with ketone, and aldehyde with ketone—can undergo this reaction. The reaction does not favor any specific pair and can indeed proceed with any combination of these carbonyl compounds. Therefore, the answer that encompasses all these combinations is accurate, as all types involved can participate effectively in aldol condensation reactions, leading to a valid outcome based on the conditions set for the reaction.