Textbook Question
Show how you would accomplish the following synthetic transformations. You may use any necessary reagents.
(a) N-ethylbenzamide → benzylethylamine
(b) ethyl benzoate → N-ethylbenzamide
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Ch. 21 - Carboxylic Acid Derivatives
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
Chapter 21, Problem 36c,d
Show how you would accomplish the following synthetic transformations. You may use any necessary reagents.
(c) pyrrolidine → N-acetylpyrrolidine
(d) γ-aminobutyric acid → pyrrolidine
Verified step by step guidance1
Step 1: For part (c), the transformation involves converting pyrrolidine into N-acetylpyrrolidine. This can be achieved by reacting pyrrolidine with acetic anhydride or acetyl chloride. These reagents introduce an acetyl group (-COCH3) to the nitrogen atom of pyrrolidine.
Step 2: The reaction mechanism for part (c) involves nucleophilic attack by the nitrogen atom of pyrrolidine on the carbonyl carbon of acetic anhydride or acetyl chloride. This forms a tetrahedral intermediate, which then collapses to release a leaving group (e.g., acetate or chloride) and forms the N-acetylpyrrolidine product.
Step 3: For part (d), the transformation involves converting γ-aminobutyric acid (GABA) into pyrrolidine. This requires cyclization of the molecule to form the pyrrolidine ring. The carboxylic acid group (-COOH) and the amino group (-NH2) are key functional groups involved in this process.
Step 4: To achieve cyclization in part (d), the carboxylic acid group can be activated using a dehydrating agent such as thionyl chloride (SOCl2) or carbodiimide reagents. This converts the carboxylic acid into a reactive intermediate (e.g., an acyl chloride or an ester), which can then react with the amino group to form the pyrrolidine ring.
Step 5: The reaction mechanism for part (d) involves intramolecular nucleophilic attack by the amino group on the activated carboxylic acid derivative, leading to ring closure and formation of pyrrolidine. This step may require heating to facilitate cyclization and drive the reaction to completion.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Amide Formation
Amide formation is a key reaction in organic chemistry where a carboxylic acid reacts with an amine to form an amide. In the transformation from pyrrolidine to N-acetylpyrrolidine, an acetic anhydride or acetyl chloride can be used to introduce the acetyl group, resulting in the formation of the amide bond. Understanding this reaction is crucial for synthesizing derivatives of amines.
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Amide Nomenclature
Decarboxylation
Decarboxylation is the process of removing a carboxyl group from a molecule, typically releasing carbon dioxide. In the transformation from γ-aminobutyric acid to pyrrolidine, decarboxylation occurs, which can be facilitated by heating or using a decarboxylation agent. This reaction is essential for converting amino acids into cyclic amines like pyrrolidine.
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Nucleophilic Substitution
Nucleophilic substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophile, resulting in the replacement of a leaving group. In the context of the transformations, the nucleophilic amine group in pyrrolidine can attack an electrophilic carbon in acyl chlorides or anhydrides to form N-acetylpyrrolidine. This concept is vital for understanding how functional groups can be modified in organic synthesis.
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Related Practice
Textbook Question
Show how you would accomplish the following syntheses using amides as intermediates. You may use any necessary reagents.
(a) benzoic acid → benzyldimethylamine
(b) pyrrolidine → N-ethylpyrrolidine
(c) cyclopentanecarboxylic acid → cyclopentanecarbonitrile
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Textbook Question
Show how you would convert the following starting materials to the indicated nitriles:
(b) phenylacetic acid → 3-phenylpropionitrile
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Textbook Question
Show how you would synthesize each compound, starting with an ester containing no more than eight carbon atoms. Any other necessary reagents may be used.
(d) Ph2CHOH
(e) PhCH2OH
(f) PhCOOH
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Textbook Question
Show how you would synthesize each compound, starting with an ester containing no more than eight carbon atoms. Any other necessary reagents may be used.
(i) HO–(CH2)8–OH
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Textbook Question
Show how you would convert the following starting materials to the indicated nitriles:
(a) phenylacetic acid → phenylacetonitrile
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