Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

21. Aldehydes and Ketones: Nucleophilic Addition

Imine vs Enamine

Organic Chemistry

21. Aldehydes and Ketones: Nucleophilic Addition

Imine vs Enamine

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5:54 minutes

Problem 8d

Textbook Question

Give the expected products of the following acid-catalyzed reactions.
(d) cyclohexanone + piperidine

Verified step by step guidance

Step 1: Recognize the type of reaction. This is an acid-catalyzed reaction involving cyclohexanone (a ketone) and piperidine (a secondary amine). Such reactions typically lead to the formation of an imine or enamine.

Step 2: Understand the mechanism. In the presence of an acid catalyst, the ketone group in cyclohexanone undergoes protonation at the oxygen atom, increasing its electrophilicity and making it more susceptible to nucleophilic attack by piperidine.

Step 3: Describe the nucleophilic attack. Piperidine, acting as a nucleophile, attacks the carbonyl carbon of cyclohexanone, forming a tetrahedral intermediate. This intermediate contains both the amine group from piperidine and the original oxygen from the ketone.

Step 4: Explain the dehydration step. Under acidic conditions, the intermediate loses a molecule of water (dehydration), leading to the formation of a double bond between the carbon and nitrogen atoms. This results in the formation of an imine (C=N bond).

Step 5: Consider the final product. Depending on the reaction conditions, the imine may tautomerize to form an enamine (C=C bond adjacent to a nitrogen atom). The final product is either an imine or enamine derived from cyclohexanone and piperidine.

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Key Concepts

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

Acid-Catalyzed Reactions

Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In organic chemistry, acids can protonate reactants, making them more electrophilic and facilitating nucleophilic attacks. This is particularly important in reactions involving carbonyl compounds, where the carbonyl carbon becomes more reactive in the presence of an acid.

Nucleophilic Addition to Carbonyls

Nucleophilic addition to carbonyls is a fundamental reaction in organic chemistry where a nucleophile attacks the electrophilic carbon of a carbonyl group (C=O). In the case of cyclohexanone, the carbonyl carbon is susceptible to attack by nucleophiles like piperidine, leading to the formation of an intermediate that can further react to yield various products, including imines or amines.

Formation of Imines

Imines are formed when a carbonyl compound reacts with a primary amine or a secondary amine under acidic conditions. In this reaction, the amine acts as a nucleophile, attacking the carbonyl carbon, followed by dehydration to eliminate water and form a double bond between the nitrogen and carbon. This process is crucial in organic synthesis and can lead to various derivatives depending on the starting materials.

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