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

25. Condensation Chemistry

Claisen Condensation

Organic Chemistry

25. Condensation Chemistry

Claisen Condensation

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4:13 minutes

Problem 38a

Textbook Question

Show what esters would undergo Claisen condensation to give the following β-keto esters.
(a)

Verified step by step guidance

Step 1: Identify the β-keto ester structure in the given compound. The β-keto ester contains a ketone group (C=O) at the β-position relative to the ester group (COOR). In this case, the compound has a ketone group adjacent to the ester group.

Step 2: Recall the Claisen condensation reaction mechanism. This reaction involves two ester molecules reacting in the presence of a strong base (such as alkoxide) to form a β-keto ester. One ester acts as the nucleophile, and the other acts as the electrophile.

Step 3: Analyze the structure of the product to deduce the esters that could combine to form it. The β-keto ester shown has two distinct alkyl groups attached to the carbonyl carbons. This suggests that two different esters were involved in the reaction.

Step 4: Break down the β-keto ester into its possible precursor esters. The ester group (COOR) and the ketone group (C=O) originate from two separate esters. For this compound, one ester likely contributes the ethyl group (CH2CH3), while the other contributes the propyl group (CH2CH2CH3).

Step 5: Write the structures of the two esters that would undergo Claisen condensation. The first ester is ethyl propanoate (CH3CH2CH2COOCH2CH3), and the second ester is ethyl acetate (CH3COOCH2CH3). These two esters react under basic conditions to form the given β-keto ester.

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Key Concepts

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

Claisen Condensation

Claisen condensation is a reaction between two esters or an ester and a carbonyl compound in the presence of a strong base, typically sodium ethoxide. This reaction results in the formation of a β-keto ester or a β-diketone. The process involves the deprotonation of an alpha hydrogen on one ester, allowing it to act as a nucleophile and attack the carbonyl carbon of another ester, leading to the formation of a new carbon-carbon bond.

β-Keto Esters

β-Keto esters are compounds that contain both a ketone and an ester functional group, with the carbonyl of the ketone located at the beta position relative to the ester group. These compounds are significant in organic synthesis as they can undergo further reactions, such as decarboxylation or aldol condensation, to form more complex molecules. Their structure allows for various reactivity patterns due to the presence of both functional groups.

Alpha Hydrogen

Alpha hydrogens are the hydrogen atoms attached to the carbon atom adjacent to a carbonyl group in a molecule. In the context of Claisen condensation, these hydrogens are crucial because they can be deprotonated by a strong base, generating a nucleophilic enolate ion. This enolate ion is essential for the reaction to proceed, as it attacks the carbonyl carbon of another ester, facilitating the formation of the β-keto ester.

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Show what esters would undergo Claisen condensation to give the following β-keto esters. (a)

Key Concepts

Claisen Condensation

β-Keto Esters

Alpha Hydrogen

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Show what esters would undergo Claisen condensation to give the following β-keto esters.
(a)