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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3:17 minutes

Problem 54f

Textbook Question

What are the products of the following reactions?
f.

Verified step by step guidance

Step 1: Identify the reactants. The first reactant is a ketone (2-pentanone), and the second reactant is ethylene glycol (HO-CH2-CH2-OH). The reaction is carried out in the presence of HCl, which acts as an acid catalyst.

Step 2: Recognize the type of reaction. This is an acetal formation reaction, where a ketone reacts with a diol (ethylene glycol) under acidic conditions to form a cyclic acetal.

Step 3: Understand the mechanism. The acid catalyst protonates the carbonyl oxygen of the ketone, increasing the electrophilicity of the carbonyl carbon. Ethylene glycol then attacks the carbonyl carbon, forming a hemiacetal intermediate.

Step 4: The hemiacetal intermediate undergoes further reaction. The hydroxyl group of the hemiacetal is protonated, leading to the loss of water and formation of a carbocation. The second hydroxyl group of ethylene glycol attacks the carbocation, forming a cyclic acetal.

Step 5: The final product is a cyclic acetal, where the ketone is protected by the ethylene glycol. This cyclic acetal is stable under acidic conditions and prevents further reactions at the carbonyl group.

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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 typically occurs in the presence of a base or acid, facilitating the nucleophilic attack of an enolate ion on a carbonyl carbon. The resulting product can further dehydrate to yield an α,β-unsaturated carbonyl compound.

Nucleophilic Addition

Nucleophilic addition is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophilic carbon atom, typically found in carbonyl compounds like aldehydes and ketones. In this context, the alcohol acts as a nucleophile, adding to the carbonyl carbon of the aldehyde, resulting in the formation of a hemiacetal or acetal, depending on the reaction conditions and the presence of acid catalysts.

Role of Acid Catalysts

Acid catalysts, such as HCl, are often used to enhance the rate of nucleophilic addition reactions by protonating the carbonyl oxygen, increasing the electrophilicity of the carbonyl carbon. This makes it more susceptible to attack by nucleophiles, such as alcohols. In the context of the given reaction, the presence of HCl facilitates the formation of the final product by promoting the addition of the alcohol to the aldehyde.

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