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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3:02 minutes

Problem 41b

Textbook Question

Acetals can serve as protecting groups for 1,2-diols, as well as for aldehydes and ketones. When the acetal is formed from acetone plus the diol, the acetal is called an acetonide. Show the acetonides formed from these diols with acetone under acid catalysis.

Verified step by step guidance

Step 1: Recognize the functional groups involved in the reaction. The provided diol structure contains two hydroxyl (-OH) groups on adjacent carbons, which can react with acetone under acid catalysis to form an acetal (specifically an acetonide).

Step 2: Understand the mechanism of acetal formation. Under acidic conditions, acetone reacts with the diol through a series of steps: protonation of the carbonyl oxygen in acetone, nucleophilic attack by one of the hydroxyl groups, and subsequent elimination of water to form a cyclic acetal.

Step 3: Analyze the structure of the diol. The two hydroxyl groups are on adjacent carbons, which allows for the formation of a five-membered cyclic acetal (acetonide) when reacting with acetone.

Step 4: Draw the intermediate steps. First, protonate the carbonyl oxygen of acetone. Then, one hydroxyl group attacks the carbonyl carbon, forming a hemiacetal intermediate. Next, the second hydroxyl group attacks, leading to the formation of the cyclic acetal.

Step 5: Represent the final acetonide structure. The cyclic acetal (acetonide) will consist of a five-membered ring where the two oxygen atoms from the diol are part of the ring, and the remaining methyl groups from acetone are attached to the ring.

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Key Concepts

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

Acetals and Their Formation

Acetals are formed from the reaction of an aldehyde or ketone with an alcohol under acidic conditions. This reaction involves the nucleophilic attack of the alcohol on the carbonyl carbon, leading to the formation of a hemiacetal, which can further react with another alcohol molecule to yield the acetal. Acetals are important in organic synthesis as they can protect carbonyl groups from unwanted reactions.

1,2-Diols

1,2-Diols, also known as glycols, contain two hydroxyl (-OH) groups on adjacent carbon atoms. They are versatile compounds in organic chemistry, often used as intermediates in synthesis. When reacted with acetone, 1,2-diols can form acetonides, which serve as protecting groups, preventing the diol from undergoing further reactions that could alter its structure.

Acid Catalysis

Acid catalysis involves the use of an acid to increase the rate of a chemical reaction. In the context of acetal formation, the acid protonates the carbonyl oxygen, making the carbonyl carbon more electrophilic and susceptible to nucleophilic attack by the alcohol. This step is crucial for the successful formation of acetals and acetonides, as it facilitates the reaction between the carbonyl compound and the alcohol.

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Textbook Question

Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents.

(e) propane-1,3-diol, H⁺

Textbook Question

Predict the major products of the following reactions.

(e)

Textbook Question

A chemist failed to generate the alcohol using the reaction shown here.

(b) How could the reaction conditions be modified to allow formation of the product?

Textbook Question

Show how each of the following compounds could be prepared from the given starting material. Each requires a protecting group.

Textbook Question

As discussed in Section 17.9.1, alkenes can be hydrogenated selectively in the presence of ketones. Suppose that was not the case, and suggest how you might use a protecting group strategy to generate A from B.

Textbook Question

Show how you would synthesize the following derivatives from appropriate carbonyl compounds.

(d)

Textbook Question

Acetals can serve as protecting groups for 1,2-diols, as well as for aldehydes and ketones. When the acetal is formed from acetone plus the diol, the acetal is called an acetonide. Show the acetonides formed from these diols with acetone under acid catalysis.

Textbook Question

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