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

Ketone and Aldehyde Synthesis Reactions

Organic Chemistry

21. Aldehydes and Ketones: Nucleophilic Addition

Ketone and Aldehyde Synthesis Reactions

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3:13 minutes

Problem 63b

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.
(b)

Verified step by step guidance

Step 1: Analyze the starting material and product. The starting material is a cyclic acetal (a compound with two ether groups attached to the same carbon), and the product is a ketone with a hydroxyl group attached to the adjacent carbon. This indicates hydrolysis of the acetal under acidic conditions.

Step 2: Protonation of the acetal oxygen. In the presence of acid (H⁺), one of the ether oxygen atoms in the acetal is protonated, increasing its electrophilicity and making the carbon attached to it more susceptible to nucleophilic attack.

Step 3: Water attacks the protonated acetal. A molecule of water (H₂O) acts as a nucleophile and attacks the electrophilic carbon, leading to the formation of a tetrahedral intermediate.

Step 4: Cleavage of the acetal bond. The tetrahedral intermediate undergoes bond cleavage, releasing one of the ether groups as an alcohol and forming a hemiacetal intermediate.

Step 5: Further hydrolysis of the hemiacetal. The hemiacetal undergoes another round of protonation and nucleophilic attack by water, leading to the formation of the final product: a ketone and an alcohol group.

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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 in organic chemistry where a nucleophile attacks an electrophilic carbon atom, typically found in carbonyl groups of aldehydes and ketones. This process leads to the formation of a tetrahedral intermediate, which can further react to yield various products, including alcohols. Understanding this mechanism is crucial for analyzing how alcohols interact with carbonyl compounds to form derivatives.

Hydrolysis Reactions

Hydrolysis reactions involve the breaking of chemical bonds through the reaction with water, often resulting in the formation of alcohols and acids. In the context of the question, hydrolysis of derivatives formed from alcohols and carbonyl compounds is essential to understand how these compounds revert to their original forms or transform into new products. Recognizing the conditions and mechanisms of hydrolysis is key to proposing accurate reaction mechanisms.

Reaction Mechanisms

A reaction mechanism is a step-by-step description of the pathway taken during a chemical reaction, detailing the sequence of elementary steps and the intermediates formed. Understanding reaction mechanisms is vital for predicting the products of reactions and for proposing how specific transformations occur. In this case, analyzing the mechanisms of hydrolysis for the derivatives formed from alcohols and carbonyls will help elucidate the overall reaction process.

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Show how the following transformations may be accomplished in good yield. You may use any additional reagents that are needed.

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Predict the product and draw the mechanism for the acid-catalyzed pinacol rearrangement of the following diols.

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Geminal diols, or 1,1-diols, are usually unstable, spontaneously losing water to give carbonyl compounds. Therefore, geminal diols are regarded as hydrated forms of ketones and aldehydes. Propose a mechanism for the acid-catalyzed loss of water from propane-2,2-diol to give acetone.

Textbook Question

In the mechanism for acetal hydrolysis shown, the ring oxygen atom was protonated first, the ring was cleaved, and then the methoxy group was lost. The mechanism could also be written to show the methoxy oxygen protonating and cleaving first, followed by ring cleavage. Draw this alternative mechanism.

Textbook Question

Draw the mechanism for the acid-catalyzed pinacol rearrangement of the following diols.

(b)

Textbook Question

Predict the product for the acid-catalyzed pinacol rearrangement of the following diols.

(b)

Textbook Question

Draw the mechanism for the acid-catalyzed pinacol rearrangement of the following diols.

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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.(b)

Key Concepts

Nucleophilic Addition

Hydrolysis Reactions

Reaction Mechanisms

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.
(b)