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Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728당신이 사용하는 게 아니라요?교과서 변경
22장, 문제 47a,b

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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Step 1: Understand the malonic ester synthesis. This method involves the alkylation of diethyl malonate (a malonic ester) followed by hydrolysis and decarboxylation to produce carboxylic acids. The key steps include: (a) deprotonation of the malonic ester to form an enolate, (b) alkylation with an alkyl halide, (c) hydrolysis of the ester groups to carboxylic acids, and (d) decarboxylation to remove one carboxyl group.
Step 2: For compound (a) 3-phenylpropanoic acid, identify the alkyl halide needed for alkylation. The target structure has a phenyl group attached to a propanoic acid backbone. The alkyl halide required would be benzyl bromide (C6H5CH2Br). This will introduce the phenyl group during alkylation.
Step 3: Perform the malonic ester synthesis for (a). (a) Deprotonate diethyl malonate using a base like sodium ethoxide to form the enolate. (b) React the enolate with benzyl bromide to attach the phenyl group. (c) Hydrolyze the ester groups using aqueous acid to form the dicarboxylic acid. (d) Heat the dicarboxylic acid to decarboxylate one carboxyl group, yielding 3-phenylpropanoic acid.
Step 4: For compound (b) 2-methylpropanoic acid, identify the alkyl halide needed for alkylation. The target structure has a methyl group attached to the second carbon of a propanoic acid backbone. The alkyl halide required would be methyl iodide (CH3I). This will introduce the methyl group during alkylation.
Step 5: Perform the malonic ester synthesis for (b). (a) Deprotonate diethyl malonate using a base like sodium ethoxide to form the enolate. (b) React the enolate with methyl iodide to attach the methyl group. (c) Hydrolyze the ester groups using aqueous acid to form the dicarboxylic acid. (d) Heat the dicarboxylic acid to decarboxylate one carboxyl group, yielding 2-methylpropanoic acid.

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주요 개념

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Malonic Ester Synthesis

Malonic ester synthesis is a method for synthesizing carboxylic acids by using malonic ester as a key starting material. This reaction involves the alkylation of 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.
추천 영상:
가이드 코스
3:33
Synthesis of Amino Acids: Acetamidomalonic Ester Synthesis Concept 1

Alkylation

Alkylation is a chemical reaction that involves the transfer of an alkyl group from one molecule to another. In the context of malonic ester synthesis, the alkylation step is crucial as it introduces the desired carbon chain into the malonic ester. This process typically uses a strong base to deprotonate the ester, making it a nucleophile that can react with an alkyl halide.
추천 영상:
03:19
Sodium Alkynide Alkylation

Decarboxylation

Decarboxylation is the process of removing a carboxyl group from a molecule, resulting in the release of carbon dioxide. In malonic ester synthesis, after hydrolysis of the alkylated product, decarboxylation occurs to yield the final carboxylic acid. This step is essential for obtaining the target compound with the correct structure and functional groups.
추천 영상:
02:32
Predict the correct structure