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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2:44 minutes

Problem 5

Textbook Question

Predict the major products of the following reactions.

Verified step by step guidance

Step 1: Analyze the reaction conditions. LDA (Lithium Diisopropylamide) is a strong, non-nucleophilic base used to deprotonate the most acidic hydrogen in the molecule, typically forming an enolate intermediate. CH3I or CH3CH2I are alkylating agents that react with the enolate to form a new C-C bond.

Step 2: For reaction (a), identify the most acidic hydrogen in the molecule. The ketone group has alpha hydrogens (hydrogens attached to the carbon adjacent to the carbonyl group). LDA will deprotonate one of these alpha hydrogens to form an enolate ion.

Step 3: The enolate formed in reaction (a) will then react with CH3I via an SN2 mechanism. The methyl group from CH3I will attach to the alpha carbon of the enolate, forming a new C-C bond.

Step 4: For reaction (b), the same process occurs. LDA deprotonates an alpha hydrogen of the cyclohexanone to form an enolate. The enolate reacts with CH3I, resulting in the methylation of the alpha carbon.

Step 5: For reaction (c), LDA deprotonates the alpha hydrogen adjacent to the carbonyl group in the bicyclic compound. The enolate formed reacts with CH3CH2I, leading to ethylation at the alpha carbon. Consider steric effects and regioselectivity in the product formation.

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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 carbonyl compounds (like ketones and aldehydes) through deprotonation at the alpha carbon. This reaction is typically facilitated by strong bases such as LDA (Lithium diisopropylamide). The resulting enolate ion is a nucleophile that can react with electrophiles, making it crucial for predicting reaction products in alkylation and acylation processes.

Alkylation of Enolates

Alkylation involves the reaction of an enolate ion with an alkyl halide, leading to the formation of a new carbon-carbon bond. The choice of alkyl halide affects the regioselectivity and stereochemistry of the product. In the context of the reactions shown, understanding how enolates react with methyl iodide (CH3I) is essential for predicting the major products.

Acylation of Enolates

Acylation is the process where an enolate reacts with an acyl chloride or an anhydride, resulting in the formation of a beta-keto ester or a beta-diketone. This reaction is significant in synthetic organic chemistry for constructing complex molecules. Recognizing the role of the enolate as a nucleophile in acylation helps in predicting the products of the reactions depicted in the question.

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