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

5:04 minutes

Problem 42a,b

Textbook Question

Predict the products from crossed Claisen condensation of the following pairs of esters. Indicate which combinations are poor choices for crossed Claisen condensations.
(a)
(b)

Verified step by step guidance

Step 1: Understand the Claisen condensation reaction. It involves the reaction of two esters in the presence of a strong base to form a β-keto ester or a β-diketone. Crossed Claisen condensation refers to the reaction between two different esters.

Step 2: Identify the esters involved in the reaction. Examine the structures provided in the images for both parts (a) and (b). Note the alkyl groups attached to the ester functional groups.

Step 3: Consider the reactivity of the esters. Esters with α-hydrogens are more reactive in Claisen condensations because they can form enolates. Determine which esters have α-hydrogens available for enolate formation.

Step 4: Predict the products. The enolate formed from one ester will attack the carbonyl carbon of the other ester, leading to the formation of a new carbon-carbon bond. Write the structure of the expected β-keto ester or β-diketone product for each pair of esters.

Step 5: Evaluate the suitability of the ester pairs for crossed Claisen condensation. Poor choices typically involve esters that lack α-hydrogens or have steric hindrance that prevents effective enolate formation or attack. Indicate which combinations are less favorable based on these criteria.

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, leading to the formation of a β-keto ester or a β-diketone. This reaction involves the nucleophilic attack of an enolate ion derived from one ester on the carbonyl carbon of another, resulting in a new carbon-carbon bond. Understanding this mechanism is crucial for predicting the products of crossed Claisen condensations.

Enolate Ion Formation

Enolate ions are formed when a strong base abstracts a proton from the α-carbon of an ester, creating a resonance-stabilized anion. This enolate can act as a nucleophile in Claisen condensation reactions. The stability of the enolate ion is influenced by the structure of the ester, making it essential to identify which esters can effectively generate enolates for successful crossed Claisen reactions.

Crossed Claisen Condensation

Crossed Claisen condensation involves the reaction of two different esters, which can lead to multiple products depending on the reactivity of the esters involved. Some combinations may yield poor results due to the possibility of self-condensation or the formation of unreactive enolates. Identifying which ester pairs are likely to react favorably is key to predicting the products and understanding the limitations of this reaction.

Watch next

Master Claisen Condensation with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Predict the products of the following Claisen condensations.

(c)

Textbook Question

Ethoxide is used as the base in the condensation of ethyl acetate to avoid some unwanted side reactions. Show what side reactions would occur if the following bases were used.

(a) sodium methoxide

(b) sodium hydroxide

Textbook Question

Esters with only one α hydrogen generally give poor yields in the Claisen condensation. Propose a mechanism for the Claisen condensation of ethyl isobutyrate, and explain why a poor yield is obtained.

Textbook Question

Predict the products of self-condensation of the following esters.

(a) methyl propanoate + NaOCH₃

(b) ethyl phenylacetate + NaOCH2CH₃

Textbook Question

Predict the products from crossed Claisen condensation of the following pairs of esters. Indicate which combinations are poor choices for crossed Claisen condensations.

(c)

(d)

Textbook Question

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

(d)

Textbook Question

Write the mechanism for the reaction of a 1,7-diester with an alkoxide ion to form a cyclic b-keto ester.

Textbook Question

Draw the products of the following reactions:

d. diethyl 1,2-benzenedicarboxylate + sodium ethoxide: (1) slow addition of ethyl acetate; (2) HCl

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap

Predict the products from crossed Claisen condensation of the following pairs of esters. Indicate which combinations are poor choices for crossed Claisen condensations.(a) (b)

Key Concepts

Claisen Condensation

Enolate Ion Formation

Crossed Claisen Condensation

Watch next

Predict the products from crossed Claisen condensation of the following pairs of esters. Indicate which combinations are poor choices for crossed Claisen condensations.
(a)
(b)