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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2:56 minutes

Problem 53b

Textbook Question

Predict the products formed when cyclohexanone reacts with the following reagents.
(b) excess CH₃OH, H⁺

Verified step by step guidance

Step 1: Recognize the functional group in cyclohexanone. Cyclohexanone is a ketone, which contains a carbonyl group (C=O). Ketones are reactive towards nucleophiles, especially under acidic or basic conditions.

Step 2: Identify the reagents. The problem specifies excess methanol (CH₃OH) and an acidic catalyst (H⁺). This combination suggests an acetal formation reaction, which occurs when a ketone reacts with an alcohol in the presence of acid.

Step 3: Understand the mechanism. In the first step of the reaction, the carbonyl oxygen of cyclohexanone is protonated by H⁺, making the carbonyl carbon more electrophilic. This facilitates a nucleophilic attack by methanol (CH₃OH) on the carbonyl carbon.

Step 4: After the nucleophilic attack, a tetrahedral intermediate is formed. This intermediate loses a molecule of water (H₂O) under acidic conditions, forming a hemiacetal. Since excess methanol is present, the hemiacetal reacts further with another molecule of methanol, leading to the formation of a full acetal.

Step 5: Predict the final product. The final product will be a cyclic acetal where the carbonyl group of cyclohexanone is replaced by two -OCH₃ groups attached to the same carbon. This is the result of the reaction between cyclohexanone and excess methanol in the presence of an acid catalyst.

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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 in a carbonyl group. In the case of cyclohexanone, the carbonyl carbon is susceptible to attack by nucleophiles, such as methanol (CH3OH), leading to the formation of an alcohol after the addition of the nucleophile.

Acid-Catalyzed Reactions

Acid-catalyzed reactions involve the use of an acid to enhance the reactivity of a substrate. In this scenario, the presence of H+ (protons) facilitates the protonation of the carbonyl oxygen in cyclohexanone, increasing the electrophilicity of the carbonyl carbon and making it more reactive towards nucleophiles like methanol.

Formation of Acetals

The reaction of a carbonyl compound with an alcohol in the presence of an acid can lead to the formation of acetals. When cyclohexanone reacts with excess methanol and acid, the initial product is a hemiacetal, which can further react with another molecule of methanol to form a full acetal, characterized by the presence of two -OCH3 groups attached to the former carbonyl carbon.

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