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

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Enolate Alkylation and Acylation

Organic Chemistry

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Enolate Alkylation and Acylation

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2:17 minutes

Problem 14b

Textbook Question

How could each of the following compounds be prepared from a ketone and an alkyl halide?
b.

Verified step by step guidance

Step 1: Identify the target compound structure. The compound shown is a β-aryl ketone, which can be synthesized using a ketone and an alkyl halide through the alkylation of enolates.

Step 2: Select the ketone precursor. The ketone precursor should be cyclopentanone, as it provides the cyclic ketone structure in the target molecule.

Step 3: Select the alkyl halide. The alkyl halide should be benzyl bromide (C6H5CH2Br), as it introduces the benzyl group to the ketone.

Step 4: Generate the enolate. Treat cyclopentanone with a strong base, such as LDA (Lithium Diisopropylamide), to form the enolate ion. This step is crucial for nucleophilic attack on the alkyl halide.

Step 5: Perform the alkylation reaction. React the enolate ion with benzyl bromide in an SN2 reaction mechanism to form the β-aryl ketone shown in the target structure.

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Key Concepts

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

Enolate Formation

Enolates are formed from ketones through deprotonation at the alpha carbon, resulting in a resonance-stabilized anion. This process is typically facilitated by a strong base, which abstracts a proton, allowing the carbonyl compound to become nucleophilic. Enolates are crucial intermediates in various organic reactions, including alkylation and acylation.

Alkylation of Enolates

Alkylation involves the reaction of an enolate ion with an alkyl halide, where the nucleophilic enolate attacks the electrophilic carbon of the halide. This reaction results in the formation of a new carbon-carbon bond, extending the carbon chain. The choice of alkyl halide can influence the regioselectivity and stereochemistry of the product formed.

Acylation of Enolates

Acylation of enolates involves the reaction of an enolate with an acyl halide or an acid anhydride, leading to the formation of a β-keto ester or a β-diketone. This process allows for the introduction of acyl groups into the molecule, which can further participate in various synthetic transformations. Acylation is a key step in the synthesis of complex organic molecules.

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Textbook Question

Show how you would accomplish the following multistep conversions. You may use any additional reagents you need.

(a)

Multiple Choice

Determine if the reaction is thermodynamically or kinetically controlled

Textbook Question

The following are all substitution reactions, two of which we study in later chapters. With no knowledge of mechanism, what would you expect the ratio of products to be for each reaction, based on a random statistical distribution?

(a) Replacing a hydrogen (H) with deuterium (D):

Textbook Question

A carboxylic acid is formed when an a-haloketone reacts with hydroxide ion. This reaction is called a Favorskii reaction. Propose a mechanism for the following Favorskii reaction. (Hint: In the first step, HO^- removes a proton from the a-carbon that is not bonded to Br; a three-membered ring is formed in the second step; and HO^- is a nucleophile in the third step.)

Textbook Question

How could each of the following compounds be prepared from a ketone and an alkyl halide?

Textbook Question

Show how the following ketones might be synthesized from the indicated acids, using any necessary reagents.

(b) methyl cyclohexyl ketone from cyclohexanecarboxylic acid

Textbook Question

Predict the products of the following reactions.

(c)

Textbook Question

Predict the major products of the following reactions.

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