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

Acetal

Organic Chemistry

21. Aldehydes and Ketones: Nucleophilic Addition

Acetal

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2:48 minutes

Problem 54d

Textbook Question

Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents.
(d) excess ethanol and acid

Verified step by step guidance

Step 1: Recognize the functional group in cyclohexanecarbaldehyde. The molecule contains an aldehyde group (-CHO) attached to a cyclohexane ring. Aldehydes are reactive and can undergo nucleophilic addition reactions.

Step 2: Understand the role of the reagents. Ethanol (CH₃CH₂OH) is an alcohol, and the presence of acid (commonly H⁺) acts as a catalyst to facilitate the reaction. Together, these reagents suggest an acetal formation reaction.

Step 3: Recall the mechanism of acetal formation. In the presence of excess alcohol and acid, aldehydes react to form acetals. The reaction proceeds through the following steps: (a) protonation of the aldehyde oxygen to make the carbonyl carbon more electrophilic, (b) nucleophilic attack by ethanol on the carbonyl carbon, (c) formation of a hemiacetal intermediate, (d) protonation and loss of water to form a carbocation, and (e) a second nucleophilic attack by ethanol to form the acetal.

Step 4: Predict the structure of the acetal product. The aldehyde group (-CHO) in cyclohexanecarbaldehyde will react with two molecules of ethanol to form a diethoxy acetal. The final product will have two ethoxy groups (-OCH₂CH₃) attached to the former carbonyl carbon.

Step 5: Verify the reaction conditions. Ensure that the reaction is carried out under acidic conditions and with excess ethanol to drive the equilibrium toward acetal formation. This ensures the aldehyde is fully converted into the acetal product.

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Key Concepts

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

Nucleophilic Addition

Nucleophilic addition is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophilic carbon atom, typically found in carbonyl compounds like aldehydes. In the case of cyclohexanecarbaldehyde, the carbonyl carbon is susceptible to attack by nucleophiles such as ethanol, leading to the formation of an alkoxide intermediate.

Acetal Formation

Acetal formation occurs when an aldehyde reacts with an alcohol in the presence of an acid catalyst. This reaction involves the nucleophilic attack of the alcohol on the carbonyl carbon, followed by protonation and subsequent elimination of water, resulting in the formation of an acetal. In this scenario, excess ethanol and acid will drive the reaction towards acetal production.

Reversible Reactions

Many organic reactions, including acetal formation, are reversible. The equilibrium between reactants and products can be influenced by factors such as concentration and temperature. In the presence of excess ethanol, the reaction favors the formation of the acetal, but under different conditions, the acetal can revert back to the aldehyde and alcohol, highlighting the dynamic nature of these chemical processes.

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Related Practice

Textbook Question

Draw the products of the following reactions:

Textbook Question

Propose mechanisms for the following reactions.

(a)

Textbook Question

Draw structures of the following derivatives.

(e) acetaldehyde dimethyl acetal

Textbook Question

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

(b) excess CH₃OH, H⁺

Textbook Question

Alcohols combine with ketones and aldehydes to form interesting derivatives, which we will discuss in Chapter 18. The following reactions show the hydrolysis of two such derivatives. Propose mechanisms for these reactions.

(a)

Textbook Question

For each compound,

1. name the functional group.

2. show what compound(s) result from complete hydrolysis.

(d)

Textbook Question

For each compound,

1. name the functional group.

2. show what compound(s) result from complete hydrolysis.

(e)

Textbook Question

There are three dioxane isomers: 1,2-dioxane, 1,3-dioxane, and 1,4-dioxane. One of these acts like an ether and is an excellent solvent for Grignard reactions. Another one is potentially explosive when heated. The third one quickly hydrolyzes in dilute acid. Show which isomer acts like a simple ether, and then explain why one of them is potentially explosive.

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Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents.(d) excess ethanol and acid

Key Concepts

Nucleophilic Addition

Acetal Formation

Reversible Reactions

Watch next

Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents.
(d) excess ethanol and acid