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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3:45 minutes

Problem 68a

Textbook Question

Show how you would use an aldol, Claisen, or another type of condensation to make each compound.
(a)

Verified step by step guidance

Step 1: Identify the target molecule and recognize the functional groups present. The compound contains an aldehyde group (-CHO) and a double bond conjugated to the aldehyde. This suggests that the molecule could be synthesized using an aldol condensation reaction.

Step 2: Break down the target molecule into potential precursors. In an aldol condensation, the product is typically formed by the reaction of an enolate ion with a carbonyl compound. Here, the molecule can be divided into two parts: (1) a cyclohexanone (providing the enolate) and (2) another cyclohexanone (acting as the electrophilic carbonyl compound).

Step 3: Write the mechanism for the aldol condensation. First, one molecule of cyclohexanone is deprotonated at the alpha-carbon by a base (e.g., NaOH) to form the enolate ion. The enolate ion then attacks the carbonyl carbon of the second cyclohexanone molecule, forming a β-hydroxyketone intermediate.

Step 4: Explain the dehydration step. The β-hydroxyketone intermediate undergoes elimination (E1cB mechanism) under basic or acidic conditions to lose water and form the α,β-unsaturated aldehyde product.

Step 5: Summarize the reaction conditions. The aldol condensation typically requires a base (e.g., NaOH or KOH) and mild heating to promote both the enolate formation and the dehydration step. Ensure the reaction is carried out under controlled conditions to avoid overreaction or polymerization.

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Key Concepts

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

Aldol Condensation

Aldol condensation is a reaction between aldehydes or ketones that contain alpha-hydrogens, leading to the formation of β-hydroxy aldehydes or ketones. This reaction involves the nucleophilic addition of an enolate ion to a carbonyl carbon, followed by dehydration to form an α,β-unsaturated carbonyl compound. It is a key reaction in organic synthesis for building complex molecules.

Claisen Condensation

Claisen condensation is a reaction between two esters or an ester and a carbonyl compound in the presence of a strong base, resulting in the formation of a β-keto ester or a β-diketone. The reaction involves the formation of an enolate ion from one ester, which then attacks the carbonyl carbon of another ester, followed by subsequent hydrolysis. This reaction is crucial for synthesizing larger carbon skeletons in organic chemistry.

Condensation Reactions

Condensation reactions are a class of reactions where two molecules combine to form a larger molecule, typically with the loss of a small molecule such as water or methanol. In organic chemistry, these reactions are essential for forming carbon-carbon bonds and constructing complex structures. Understanding the mechanisms and conditions for these reactions is vital for effective synthesis in organic chemistry.

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Related Practice

Textbook Question

There are other condensation reactions similar to the aldol and Claisen condensations:

a. The Perkin condensation is the condensation of an aromatic aldehyde and acetic anhydride. Draw the product obtained from the following Perkin condensation:

Textbook Question

What product is obtained when the product of a Knoevenagel condensation is heated in an aqueous acidic solution?

Textbook Question

There are other condensation reactions similar to the aldol and Claisen condensations:

c. The Knoevenagel condensation is the condensation of an aldehyde or a ketone that has no a-hydrogens and a compound such as diethyl malonate that has an a-carbon flanked by two electron-withdrawing groups. Draw the product obtained from the following Knoevenagel condensation:

Textbook Question

The Knoevenagel condensation is a special case of the aldol condensation in which an active methylene compound reacts with an aldehyde or ketone, in the presence of a secondary amine as a basic catalyst, to produce a new C=C. Show the starting materials that made each of these by a Knoevenagel condensation.

(a)

Textbook Question

Propose mechanisms for the reactions shown in Problems 22-63 part (b).

Textbook Question

Show how you would use an aldol, Claisen, or another type of condensation to make each compound.

(f)

Textbook Question

Propose a mechanism for the crossed Claisen condensation between ethyl acetate and ethyl benzoate.

Multiple Choice

Draw the structure of the Claisen condensation product for each of the following compounds.

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Show how you would use an aldol, Claisen, or another type of condensation to make each compound. (a)

Key Concepts

Aldol Condensation

Claisen Condensation

Condensation Reactions

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Show how you would use an aldol, Claisen, or another type of condensation to make each compound.
(a)