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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5:37 minutes

Problem 72

Textbook Question

Show how you would use the malonic ester synthesis to make the following compounds.

Verified step by step guidance

Step 1: Understand the malonic ester synthesis. It is a method used to synthesize carboxylic acids by alkylating diethyl malonate (a malonic ester) and then hydrolyzing and decarboxylating the product. The key steps involve enolate formation, alkylation, hydrolysis, and decarboxylation.

Step 2: For compound (a), cyclohexylacetic acid: Start with diethyl malonate. Use a base like sodium ethoxide to form the enolate ion. Then, alkylate the enolate with cyclohexylmethyl bromide (or a similar alkyl halide) to introduce the cyclohexyl group.

Step 3: For compound (b), phenylbutyric acid: Begin with diethyl malonate. Form the enolate using a base, and then alkylate it with phenylethyl bromide (or a similar alkyl halide) to introduce the phenylethyl group. This will extend the chain to include the phenyl group.

Step 4: For compound (c), cyclopentylacetic acid: Start with diethyl malonate. Form the enolate using a base, and then alkylate it with cyclopentylmethyl bromide (or a similar alkyl halide) to introduce the cyclopentyl group.

Step 5: For all compounds (a), (b), and (c): After alkylation, hydrolyze the ester groups using aqueous acid (e.g., HCl) to form the dicarboxylic acid. Then, decarboxylate the product by heating to remove one carboxyl group, yielding the desired carboxylic acid.

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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 using malonic ester as a key intermediate. This reaction involves the alkylation of a malonic ester followed by hydrolysis and decarboxylation, allowing for the introduction of alkyl groups and the formation of a carboxylic acid. It is particularly useful for creating compounds with a specific carbon chain length and functional groups.

Decarboxylation

Decarboxylation is the process of removing a carboxyl group (-COOH) from a molecule, resulting in the release of carbon dioxide (CO2). In the context of malonic ester synthesis, decarboxylation occurs after hydrolysis, leading to the formation of a carbonyl compound. This step is crucial for obtaining the final product with the desired structure and functional groups.

Functional Group Transformation

Functional group transformation refers to the process of converting one functional group into another within a molecule. In malonic ester synthesis, the introduction of various functional groups, such as hydroxyl (-OH) or carbonyl (C=O) groups, can be achieved through strategic reactions. Understanding how to manipulate functional groups is essential for designing synthetic pathways to achieve specific target compounds.

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Related Practice

Textbook Question

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

Textbook Question

b. What carboxylic acid is formed when the malonic ester synthesis is carried out with two equivalents of malonic ester, one equivalent of 1,5-dibromopentane, and two equivalents of base?

Textbook Question

Amobarbital is a sedative marketed under the trade name Amytal. Propose a synthesis of amobarbital, using diethyl malonate and urea as two of the starting materials.

Textbook Question

Show how the following compounds can be made using the malonic ester synthesis.

(a) 3-phenylpropanoic acid

(b) 2-methylpropanoic acid

Textbook Question

Show the structure of the compound that results from hydrolysis and decarboxylation of the product.

Textbook Question

Show how the following compounds can be made using the malonic ester synthesis.

(d) cyclopentanecarboxylic acid

Textbook Question

What alkyl bromide(s) should be used in the malonic ester synthesis of each of the following carboxylic acids?

a. propanoic acid