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

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Malonic Ester Synthesis

Organic Chemistry

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Malonic Ester Synthesis

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3:20 minutes

Problem 40c

Textbook Question

Explain why the following carboxylic acids cannot be prepared by a malonic ester synthesis:
c.

Verified step by step guidance

Step 1: Understand the malonic ester synthesis process. Malonic ester synthesis is a method used to prepare carboxylic acids by alkylating malonic ester (diethyl malonate) and then hydrolyzing and decarboxylating the product. The key requirement is that the alkylation step must occur at a position where the malonic ester can form a stable intermediate.

Step 2: Analyze the structure of the given carboxylic acid. The carboxylic acid shown has a cyclopentyl group attached to a carbon adjacent to the carboxylic acid functional group. This structure suggests that the alkylation step would involve introducing a cyclopentyl group.

Step 3: Consider steric hindrance in the alkylation step. The cyclopentyl group is bulky, and introducing it via alkylation of malonic ester would be sterically hindered. This makes the reaction less likely to proceed efficiently.

Step 4: Evaluate the stability of intermediates. During malonic ester synthesis, the intermediate formed after alkylation must be stable enough to undergo hydrolysis and decarboxylation. The bulky cyclopentyl group may destabilize the intermediate, preventing successful synthesis.

Step 5: Conclude why malonic ester synthesis is not suitable. Due to steric hindrance and potential instability of intermediates, the given carboxylic acid cannot be prepared using malonic ester synthesis.

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Key Concepts

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

Malonic Ester Synthesis

Malonic ester synthesis is a method for synthesizing carboxylic acids by alkylating malonic ester followed by hydrolysis and decarboxylation. This reaction typically requires a simple alkyl halide and results in a carboxylic acid with a two-carbon extension from the malonic ester. Understanding this process is crucial to determine why certain carboxylic acids cannot be synthesized using this method.

Structural Constraints

The structure of the target carboxylic acid plays a significant role in determining its feasibility for synthesis via malonic ester synthesis. If the desired acid contains functional groups or structural features that cannot be introduced through the malonic ester pathway, such as cyclic structures or specific stereochemistry, it cannot be synthesized using this method. Analyzing the structure of the acid is essential to identify these constraints.

Reactivity of Intermediates

In malonic ester synthesis, the reactivity of intermediates formed during the reaction is critical. The malonic ester must be able to undergo nucleophilic substitution with an alkyl halide, and the resulting intermediate must be stable enough to proceed through hydrolysis and decarboxylation. If the intermediates formed from the target carboxylic acid are unstable or reactive in a way that leads to side reactions, the synthesis will not be successful.

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Explain why the following carboxylic acids cannot be prepared by a malonic ester synthesis:c.

Key Concepts

Malonic Ester Synthesis

Structural Constraints

Reactivity of Intermediates

Watch next

Explain why the following carboxylic acids cannot be prepared by a malonic ester synthesis:
c.