Textbook Question
Show how you would accomplish each conversion using an enamine synthesis with pyrrolidine as the secondary amine.
(a) cyclopentanone → 2-allylcyclopentanone
(b) pentan-3-one → 2-methyl-1-phenylpentan-3-one
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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 8b
Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 8bChapter 22, Problem 8b
Give the expected products of the following acid-catalyzed reactions.
(b) acetophenone + dimethylamine
Verified step by step guidance1
Identify the type of reaction: This is an acid-catalyzed reaction between acetophenone (a ketone) and dimethylamine (a secondary amine). Such reactions typically lead to the formation of an imine or an enamine, depending on the conditions.
Understand the mechanism: In the presence of an acid catalyst, the carbonyl group of acetophenone (C=O) becomes protonated, increasing its electrophilicity. This makes the carbonyl carbon more susceptible to nucleophilic attack by dimethylamine.
Describe the nucleophilic attack: The lone pair of electrons on the nitrogen atom of dimethylamine attacks the carbonyl carbon of acetophenone, forming a tetrahedral intermediate.
Explain the dehydration step: After the tetrahedral intermediate forms, a proton transfer occurs, followed by the elimination of water (H2O). This step is facilitated by the acid catalyst and leads to the formation of an imine or enamine product.
Determine the final product: Since dimethylamine is a secondary amine, the reaction will likely result in the formation of an enamine. The enamine structure will have a C=C bond adjacent to the nitrogen atom of dimethylamine.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acid-Catalyzed Reactions
Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In organic chemistry, acids can protonate reactants, making them more electrophilic and facilitating nucleophilic attacks. This is particularly important in reactions involving carbonyl compounds, where the carbonyl carbon becomes more reactive in the presence of an acid.
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Acid Catalyzed
Nucleophilic Addition to Carbonyls
Nucleophilic addition to carbonyls is a fundamental reaction in organic chemistry where a nucleophile attacks the electrophilic carbon of a carbonyl group (C=O). In the case of acetophenone, the carbonyl carbon is susceptible to attack by nucleophiles like dimethylamine, leading to the formation of an intermediate that can undergo further transformations, such as protonation or dehydration.
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Formation of Imines
The formation of imines is a key reaction where a primary amine reacts with a carbonyl compound, resulting in the formation of an imine (C=N) after the elimination of water. In the context of acetophenone and dimethylamine, the reaction will yield an imine product, which is characterized by a double bond between carbon and nitrogen, and is often formed under acidic conditions that facilitate the dehydration step.
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Related Practice
Textbook Question
Propose a mechanism for the acid-catalyzed reaction of cyclohexanone with pyrrolidine.
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Textbook Question
Without looking back, propose a mechanism for the hydrolysis of this iminium salt to the alkylated ketone. The first step is attack by water, followed by loss of a proton to give a carbinolamine. Protonation on nitrogen allows pyrrolidine to leave, giving the protonated ketone.
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Textbook Question
Give the expected products of the following acid-catalyzed reactions.
(c) cyclohexanone + aniline
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Textbook Question
Give the expected products of the following acid-catalyzed reactions.
(a) acetophenone + methylamine
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Textbook Question
Give the expected products of the following acid-catalyzed reactions.
(d) cyclohexanone + piperidine
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