Using cyclopentanone as the reactant, show the product of a. acid-catalyzed keto–enol interconversion.

Verified step by step guidance

1. Identify the structure of cyclopentanone, which is a five-membered ring with a ketone functional group.
2. Understand the concept of keto-enol tautomerism, where the ketone (keto form) can reversibly convert to an enol form. This involves the migration of a hydrogen atom and the shift of a double bond.
3. In the presence of an acid catalyst, the hydrogen from the acid will protonate the oxygen of the ketone, increasing the electrophilicity of the carbonyl carbon.
4. A hydrogen atom adjacent to the carbonyl group (from a carbon in the ring) will shift to the oxygen, forming a double bond between the carbonyl carbon and the adjacent carbon. This results in the formation of the enol form.
5. The final product will be the enol form of cyclopentanone, which features a double bond between two of the carbons in the ring and an OH group attached to one of these carbons.

Key Concepts

Keto-Enol Tautomerism

Keto-enol tautomerism is a chemical equilibrium between a keto form (a carbonyl compound) and its corresponding enol form (an alcohol with a double bond). In this process, the hydrogen atom shifts from the carbon adjacent to the carbonyl to the oxygen, resulting in the formation of the enol. This concept is crucial for understanding how cyclopentanone can interconvert between its keto and enol forms under acidic conditions.

Acid-Catalyzed Reaction

An acid-catalyzed reaction involves the use of an acid to increase the rate of a chemical reaction. In the context of keto-enol interconversion, the acid protonates the carbonyl oxygen, making the carbonyl carbon more electrophilic and facilitating the transfer of the hydrogen atom to form the enol. This mechanism highlights the role of acids in stabilizing intermediates and promoting reaction pathways.

Cyclopentanone Structure

Cyclopentanone is a cyclic ketone with a five-membered ring containing a carbonyl group. Its structure influences the stability of the keto and enol forms, as steric and electronic factors can affect the equilibrium between these tautomers. Understanding the molecular structure of cyclopentanone is essential for predicting the outcome of the acid-catalyzed keto-enol interconversion and the relative amounts of each tautomer.