Textbook Question
Give the products expected when the following tertiary amines are treated with a peroxyacid and heated.
(b) N,N-diethylhexan-2-amine
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Ch. 19 - Amines
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 19, Problem 22a
When the (R,R) isomer of the amine shown is treated with an excess of methyl iodide, then silver oxide, then heated, the major product is the Hofmann product.
(a) Draw the structure of the major (Hofmann) product.
Verified step by step guidance1
Step 1: Recognize that the reaction involves the Hofmann elimination process, which occurs when an amine is treated with excess methyl iodide, followed by silver oxide and heat. This process converts the amine into a quaternary ammonium salt, which undergoes elimination to form an alkene.
Step 2: Analyze the starting amine structure. The given amine is a tertiary amine with two methyl groups and a bulky isopropyl group attached to the nitrogen. The elimination will occur to form the least substituted alkene (Hofmann product) due to steric hindrance.
Step 3: Treat the amine with excess methyl iodide. This step methylates the nitrogen, forming a quaternary ammonium iodide salt. The nitrogen now has a positive charge, and the iodide acts as a counterion.
Step 4: Add silver oxide (Ag2O) and water. This step replaces the iodide ion with a hydroxide ion, forming a quaternary ammonium hydroxide salt. The hydroxide ion acts as a base in the elimination reaction.
Step 5: Heat the quaternary ammonium hydroxide salt. The elimination reaction occurs, and the least substituted alkene (Hofmann product) is formed as the major product. In this case, the major product is the terminal alkene, as shown in the diagram.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hofmann Rearrangement
The Hofmann rearrangement is a chemical reaction that converts primary amides into primary amines with the loss of one carbon atom. This reaction involves the treatment of the amide with halogens and a base, leading to the formation of an isocyanate intermediate, which is then hydrolyzed to yield the amine. Understanding this mechanism is crucial for predicting the products when an amine is treated with methyl iodide and silver oxide.
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General Reaction
Methylation of Amines
Methylation of amines involves the introduction of a methyl group into the amine structure, typically using methyl iodide as a methylating agent. This process can lead to the formation of N-methylated products, which can further react under certain conditions. Recognizing how methylation affects the structure and reactivity of amines is essential for determining the final product in the given reaction sequence.
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Sterics and Reactivity in Organic Chemistry
Sterics refers to the spatial arrangement of atoms in a molecule and how this affects its reactivity. In the context of the (R,R) isomer of the amine, steric hindrance can influence the outcome of reactions, such as the Hofmann rearrangement and subsequent methylation. Understanding steric effects is vital for predicting which products will be favored in a reaction, especially when multiple pathways are possible.
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Related Practice
Textbook Question
Give the products expected when the following tertiary amines are treated with a peroxyacid and heated.
(c) cyclohexyldimethylamine
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Textbook Question
Predict the products from the reactions of the following amines with sodium nitrite in dilute HCl.
(b) N-ethylhexan-2-amine
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Textbook Question
When the (R,R) isomer of the amine shown is treated with an excess of methyl iodide, then silver oxide, then heated, the major product is the Hofmann product.
(b) Some Zaitsev product is also formed. It has the (E) configuration. When the same amine is treated with mCPBA and heated, the Zaitsev product has the (Z) configuration. Use stereochemical drawings of the transition states to explain these observations.
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Textbook Question
Give the products expected when the following tertiary amines are treated with a peroxyacid and heated.
(d) N-ethylpiperidine
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Textbook Question
Predict the products from the reactions of the following amines with sodium nitrite in dilute HCl.
(c) piperidine