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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3:37 minutes

Problem 38b

Textbook Question

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

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 phenyl group (Ph) attached to the α-carbon and another phenyl group attached to the β-carbon.

Step 2: Recall the Claisen condensation 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 starting esters. The product has two distinct ester groups: one with a methyl group (OCH₃) and the other with a phenyl group (Ph-CH₂). This suggests that the starting esters are methyl benzoate (Ph-CH₂-COOCH₃) and methyl phenylacetate (Ph-CH₂-COOCH₃).

Step 4: Write the reaction setup. In the Claisen condensation, the enolate ion formed from one ester (via deprotonation at the α-carbon) attacks the carbonyl carbon of the second ester. This leads to the formation of the β-keto ester after elimination of the alkoxide group.

Step 5: Verify the compatibility of the starting esters with the product. Ensure that the phenyl groups and methyl groups in the product match the substituents in the starting esters. The reaction conditions typically involve a base like sodium ethoxide (NaOEt) in ethanol (EtOH) to facilitate the condensation.

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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, leading to the formation of a β-keto ester or a β-diketone. This reaction involves the nucleophilic attack of an enolate ion on the carbonyl carbon of another ester, followed by the elimination of an alcohol. Understanding this mechanism is crucial for predicting the products formed in the reaction.

Enolate Ion Formation

Enolate ions are formed when a base abstracts a proton from the α-carbon of an ester or carbonyl compound, resulting in a resonance-stabilized anion. This enolate ion acts as a nucleophile in Claisen condensation, attacking the carbonyl carbon of another ester. Recognizing how to generate and utilize enolate ions is essential for successfully carrying out and understanding Claisen reactions.

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 β-position relative to the ester group. They are significant intermediates in organic synthesis and can be formed through Claisen condensation. Identifying the structure and properties of β-keto esters is important for understanding the outcomes of the Claisen reaction and their subsequent reactivity.

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

Key Concepts

Claisen Condensation

Enolate Ion Formation

β-Keto Esters

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