Predict the products of the following reactions.
(d)

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Step 1: Identify the reactants and reaction conditions. The reactants are formaldehyde (HCHO) and cyclohexanone (C6H10O), and the reaction is carried out in the presence of a hydroxide ion (OH⁻) and heat (Δ). This suggests an aldol condensation reaction.

Step 2: Determine the enolate formation. Cyclohexanone has an alpha hydrogen, which can be deprotonated by the hydroxide ion to form an enolate ion. The enolate ion is nucleophilic and will attack the electrophilic carbonyl carbon of formaldehyde.

Step 3: Describe the nucleophilic addition step. The enolate ion attacks the carbonyl carbon of formaldehyde, forming a beta-hydroxy ketone intermediate. This intermediate is characteristic of the aldol addition reaction.

Step 4: Explain the dehydration step. Under the influence of heat (Δ), the beta-hydroxy ketone undergoes elimination of water (H₂O) to form an α,β-unsaturated ketone. This step is known as aldol condensation.

Step 5: Predict the final product. The final product will be an α,β-unsaturated ketone where the double bond is conjugated with the carbonyl group. The structure will consist of a cyclohexane ring with a double bond adjacent to the ketone group, and the formaldehyde-derived carbon will be part of the conjugated system.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Aldol Condensation

Aldol condensation is a reaction between aldehydes or ketones that contain alpha-hydrogens, leading to the formation of β-hydroxy aldehydes or ketones. This reaction involves the nucleophilic addition of an enolate ion to a carbonyl compound, followed by dehydration to yield an α,β-unsaturated carbonyl compound. Understanding this mechanism is crucial for predicting the products of the reaction shown.

Enolate Ion Formation

Enolate ions are formed when a carbonyl compound, such as an aldehyde or ketone, is deprotonated at the alpha position. This ion acts as a nucleophile in aldol reactions, attacking the carbonyl carbon of another molecule. Recognizing how enolate ions are generated and their role in the reaction mechanism is essential for predicting the products of the aldol condensation.

Dehydration Step

The dehydration step in aldol condensation involves the elimination of a water molecule from the β-hydroxy carbonyl compound, resulting in the formation of an α,β-unsaturated carbonyl compound. This step is driven by the stability of the resulting double bond and is often facilitated by heat. Understanding this step is important for accurately predicting the final products of the reaction.

Predict the products of the following reactions.(d)