Textbook Question
Show how the following compounds can be made using the malonic ester synthesis.
(a) 3-phenylpropanoic acid
(b) 2-methylpropanoic acid
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Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
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Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 47c,d
Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 47c,dChapter 22, Problem 47c,d
Show how the following compounds can be made using the malonic ester synthesis.
(c) 4-phenylbutanoic acid
(d) cyclopentanecarboxylic acid
Verified step by step guidance1
Step 1: Understand the malonic ester synthesis. This is a method used to synthesize carboxylic acids by alkylating the alpha-carbon of diethyl malonate (or another malonic ester) followed by hydrolysis and decarboxylation. The key steps involve enolate formation, alkylation, hydrolysis, and decarboxylation.
Step 2: For 4-phenylbutanoic acid, identify the target structure. The molecule has a phenyl group attached to the fourth carbon of a butanoic acid chain. To achieve this, start with diethyl malonate and generate the enolate ion by treating it with a strong base such as sodium ethoxide (NaOEt).
Step 3: Perform alkylation. React the enolate ion with an appropriate alkyl halide, such as benzyl bromide (C6H5CH2Br), to introduce the phenyl group. This step forms a substituted malonic ester intermediate with a benzyl group attached to the alpha-carbon.
Step 4: Hydrolyze the ester groups. Treat the substituted malonic ester with aqueous acid (H3O+) or base (NaOH) to hydrolyze both ester groups into carboxylic acids, forming a dicarboxylic acid intermediate.
Step 5: Decarboxylate the dicarboxylic acid. Heat the dicarboxylic acid intermediate to remove one carboxyl group as CO2, yielding 4-phenylbutanoic acid. Repeat a similar process for cyclopentanecarboxylic acid, but use an alkyl halide like 1-bromopentane to form a cyclopentyl group during alkylation.
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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 malonic ester followed by hydrolysis and decarboxylation, allowing for the introduction of alkyl groups. It is particularly useful for creating compounds with a specific carbon chain length and functional groups.
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Alkylation
Alkylation is a chemical process where an alkyl group is transferred to a molecule, typically through a nucleophilic substitution reaction. In the context of malonic ester synthesis, the alkylation step is crucial as it determines the structure of the final carboxylic acid product. The choice of alkyl halide used in this step influences the carbon skeleton of the resulting compound.
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Decarboxylation
Decarboxylation is the process of removing a carboxyl group from a molecule, resulting in the release of carbon dioxide. In malonic ester synthesis, decarboxylation occurs after hydrolysis of the alkylated malonic ester, leading to the formation of the desired carboxylic acid. This step is essential for achieving the final product with the correct structure and functional groups.
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Related Practice
Textbook Question
In Solved Problem 22-9, the target molecule was synthesized using a Michael addition to form the bond that is β,γ to the upper carbonyl group. Another approach is to use a Michael addition to form the bond that is β,γ to the other (lower) carbonyl group. Show how you would accomplish this alternative synthesis.
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Textbook Question
Show the ketones that would result from hydrolysis and decarboxylation of the following β-keto esters.
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Textbook Question
Show how the following ketones might be synthesized by using the acetoacetic ester synthesis.
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Textbook Question
Show the resonance forms for the enolate ions that result when the following compounds are treated with a strong base.
(d) nitroacetone
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Textbook Question
Show the resonance forms for the enolate ions that result when the following compounds are treated with a strong base.
(c) ethyl α-cyanoacetate
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