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

Previous problemNext problem

2:38 minutes

Problem 63a,b

Textbook Question

Predict the products of the following Claisen condensations.
(a)
(b)

Verified step by step guidance

Step 1: Identify the reaction type. The Claisen condensation involves the reaction of an ester with a base to form a β-keto ester. The base used here is methoxide (−OCH₃) in methanol (CH₃OH).

Step 2: Analyze the structure of the starting ester. In part (a), the ester is methyl isobutyrate (CH₃)₂CHCH₂COOCH₃. In part (b), the ester is methyl cyclohexylacetate, which contains a cyclohexane ring and a methyl group attached to the α-carbon.

Step 3: Deprotonation of the α-hydrogen. The methoxide base will abstract the acidic α-hydrogen from the ester, forming an enolate ion. This enolate ion is stabilized by resonance between the α-carbon and the carbonyl group.

Step 4: Nucleophilic attack of the enolate. The enolate ion will attack the carbonyl carbon of another ester molecule, leading to the formation of a new C-C bond. This step results in the formation of a tetrahedral intermediate.

Step 5: Elimination of the leaving group. The tetrahedral intermediate will collapse, expelling the methoxide ion (−OCH₃) as a leaving group. This results in the formation of a β-keto ester as the final product for both reactions.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

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 the mechanism involves recognizing the nucleophilic attack of the enolate ion on the carbonyl carbon, followed by the elimination of an alcohol.

Enolate Ion Formation

Enolate ions are formed when a base abstracts a proton from the alpha carbon of a carbonyl compound, resulting in a resonance-stabilized anion. This species is crucial in Claisen condensation as it acts as a nucleophile, attacking another carbonyl compound. The stability of the enolate ion influences the reaction's efficiency and product distribution.

Product Prediction

Predicting the products of a Claisen condensation requires understanding the structure of the starting materials and the regioselectivity of the reaction. The outcome depends on the nature of the carbonyl compounds involved, as well as any substituents that may influence sterics and electronics. Analyzing the reaction mechanism helps in determining the final products formed after the condensation and subsequent elimination of alcohol.

Watch next

Master Claisen Condensation with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Show how Claisen condensations could be used to make the following compounds.

(a)

Textbook Question

Show how Claisen condensations could be used to make the following compounds.

(b)

Textbook Question

Show how Claisen condensations could be used to make the following compounds.

(c)

Textbook Question

Show how Claisen condensations could be used to make the following compounds.

(d)

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)

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap

Predict the products of the following Claisen condensations.(a) (b)

Key Concepts

Claisen Condensation

Enolate Ion Formation

Product Prediction

Watch next

Predict the products of the following Claisen condensations.
(a)
(b)