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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Problem 44b

Textbook Question

Predict the major products of the following crossed Claisen condensations.
(b)

Verified step by step guidance

Step 1: Understand the Claisen condensation reaction. A Claisen condensation involves the reaction between two esters or one ester and a ketone in the presence of a strong base, typically an alkoxide, to form a β-keto ester or β-diketone. Crossed Claisen condensations occur between two different esters or an ester and a ketone.

Step 2: Identify the reactants in the crossed Claisen condensation. Determine which compounds are involved in the reaction and note their functional groups (e.g., ester or ketone). This will help predict the nucleophile and electrophile in the reaction.

Step 3: Determine the nucleophile. The nucleophile is typically the enolate ion formed by deprotonation of the α-hydrogen of the ester or ketone. Write the enolate structure using MathML:

{CH}_{2} - COOR

Step 4: Determine the electrophile. The electrophile is the carbonyl carbon of the ester or ketone that will undergo nucleophilic attack. Write the electrophile structure using MathML:

R' COOR

Step 5: Predict the major product. After the nucleophilic attack, the intermediate undergoes elimination of the leaving group (typically an alkoxide ion), resulting in the formation of a β-keto ester or β-diketone. Write the general product structure using MathML:

R' CO - {CH}_{2} COOR

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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. Understanding this mechanism is crucial for predicting the products, as it involves nucleophilic attack and subsequent elimination of an alcohol.

Crossed Claisen Condensation

Crossed Claisen condensation refers to a variation of the Claisen reaction where two different carbonyl compounds are used. This can lead to a mixture of products, making it essential to identify which compound acts as the nucleophile and which as the electrophile. The selectivity of the reaction is influenced by the reactivity of the carbonyl compounds involved.

Product Prediction

Predicting the major products of a crossed Claisen condensation requires an understanding of the sterics and electronics of the reactants. Factors such as the stability of the resulting enolate and the ability of the carbonyl compounds to stabilize the negative charge play a significant role. Analyzing these aspects helps in determining the most likely product formed during the reaction.

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Predict the major products of the following crossed Claisen condensations. (b)

Key Concepts

Claisen Condensation

Crossed Claisen Condensation

Product Prediction

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Predict the major products of the following crossed Claisen condensations.
(b)