In an aldol condensation, the dehydrated product is best described as which type of compound?

• A. A saturated carbonyl compound
• B. A β-hydroxy carbonyl compound
• C. An α,β-unsaturated carbonyl compound (enone or enal)
• D. A cycloalkanone

Answer: (C)

In an aldol condensation, after the aldol addition the dehydration step removes water to form a double bond between the α and β carbons while the carbonyl group remains. This creates a conjugated system where the carbonyl and the carbon–carbon double bond extend across, giving an α,β-unsaturated carbonyl compound (an enone if the carbonyl is a ketone, or an enal if it’s an aldehyde). The conjugation stabilizes the product, making this description the best fit. The β-hydroxy carbonyl is the intermediate before dehydration, not the dehydrated product, and a saturated carbonyl lacks the C=C, while a cycloalkanone implies a ring structure not typically produced in this dehydration step.