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

Previous problemNext problem

2:23 minutes

Problem 67

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.

Verified step by step guidance

Identify the functional groups in compound B. It contains an alkene and a ketone group. The goal is to selectively hydrogenate the alkene without affecting the ketone.

Consider using a protecting group strategy to shield the ketone from hydrogenation conditions. A common protecting group for ketones is the acetal, which can be formed by reacting the ketone with a diol under acidic conditions.

React compound B with a diol, such as ethylene glycol, in the presence of an acid catalyst to form the acetal protecting group. This will temporarily convert the ketone into an acetal, which is stable under hydrogenation conditions.

Perform the hydrogenation reaction on the alkene. Use a catalyst like palladium on carbon (Pd/C) under hydrogen gas to selectively reduce the alkene to an alkane while the ketone is protected as an acetal.

Finally, remove the acetal protecting group by hydrolysis. Treat the compound with aqueous acid to regenerate the ketone from the acetal, yielding compound A.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

Hydrogenation of Alkenes

Hydrogenation is a chemical reaction that involves the addition of hydrogen (H2) to an alkene, converting it into an alkane. This process typically requires a catalyst, such as palladium or platinum, and can be selective, meaning it can target specific double bonds in the presence of other functional groups. Understanding the conditions and selectivity of hydrogenation is crucial for manipulating alkenes in organic synthesis.

Protecting Groups

Protecting groups are temporary modifications used in organic synthesis to shield reactive functional groups from undesired reactions during a multi-step synthesis. By selectively protecting certain groups, chemists can control the reactivity of molecules, allowing for specific transformations without interference. This strategy is essential when dealing with complex molecules that contain multiple functional groups.

Functional Group Interconversion

Functional group interconversion refers to the process of transforming one functional group into another within a molecule. This concept is fundamental in organic chemistry as it allows chemists to modify the reactivity and properties of compounds. Understanding how to effectively perform these conversions is key to designing synthetic pathways, especially when protecting groups are involved.

Watch next

Master General Reactions with a bite sized video explanation from Johnny

Start learning