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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3:10 minutes

Problem 53e

Textbook Question

Predict the products formed when cyclohexanone reacts with the following reagents.
(e) phenylhydrazine and weak acid

Verified step by step guidance

Step 1: Recognize the type of reaction. Cyclohexanone is a ketone, and phenylhydrazine reacts with ketones in the presence of a weak acid to form hydrazones. This is a condensation reaction where the carbonyl group of the ketone reacts with the hydrazine derivative.

Step 2: Write the general reaction mechanism. The carbonyl group (C=O) of cyclohexanone undergoes nucleophilic attack by the nitrogen atom of phenylhydrazine. This forms an intermediate where the oxygen is protonated by the weak acid.

Step 3: Eliminate water. After the intermediate is formed, a dehydration step occurs, where a molecule of water is eliminated. This results in the formation of a double bond between the carbon of the former carbonyl group and the nitrogen of phenylhydrazine.

Step 4: Represent the product. The final product is a cyclohexanone phenylhydrazone, where the phenyl group (C₆H₅) is attached to the nitrogen atom, and the nitrogen is double-bonded to the carbon of the former carbonyl group.

Step 5: Verify the reaction conditions. Ensure that the reaction occurs under weakly acidic conditions, as the acid catalyzes the dehydration step and stabilizes the intermediate during the reaction.

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Key Concepts

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

Cyclohexanone Structure and Reactivity

Cyclohexanone is a cyclic ketone with a six-membered carbon ring and a carbonyl group (C=O). Its reactivity is primarily due to the electrophilic nature of the carbonyl carbon, which can undergo nucleophilic addition reactions. Understanding its structure helps predict how it will interact with various reagents, such as phenylhydrazine.

Phenylhydrazine as a Reagent

Phenylhydrazine is an organic compound commonly used to form hydrazones with carbonyl compounds. It acts as a nucleophile, attacking the electrophilic carbonyl carbon of ketones and aldehydes. This reaction is significant in organic synthesis and can be used to identify carbonyl-containing compounds through the formation of stable derivatives.

Acid-Catalyzed Reactions

Weak acids can facilitate the reaction between phenylhydrazine and cyclohexanone by protonating the carbonyl oxygen, increasing the electrophilicity of the carbonyl carbon. This acid-catalyzed mechanism is crucial for enhancing the nucleophilic attack and ensuring the successful formation of the hydrazone product.

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