Textbook Question
Excess ammonia must be used when a primary amine is synthesized by reductive amination. What product will be obtained if the reaction is carried out with excess carbonyl compound?
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Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid DerivativesProblem 33a,b
Bruice 8th EditionCh. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid DerivativesProblem 33a,bChapter 17, Problem 33a,b
What are the products of the following reactions? (A trace amount of acid is present in each case.)
a. cyclopentanone + ethylamine
b. cyclopentanone + diethylamine
Verified step by step guidance1
Identify the type of reaction occurring in each case. Cyclopentanone is a ketone, and the presence of an amine (ethylamine or diethylamine) along with a trace amount of acid suggests that these are nucleophilic addition-elimination reactions, potentially forming imines or enamines.
For part (a), cyclopentanone reacts with ethylamine (a primary amine). The reaction mechanism involves the nucleophilic attack of the amine's nitrogen on the carbonyl carbon of cyclopentanone, forming a tetrahedral intermediate.
In the presence of a trace amount of acid, the intermediate undergoes protonation and dehydration (loss of water), leading to the formation of an imine. The general structure of the imine will be: \( \text{C}_5\text{H}_8=\text{N}-\text{CH}_2\text{CH}_3 \).
For part (b), cyclopentanone reacts with diethylamine (a secondary amine). Secondary amines cannot form imines because they lack a hydrogen atom on the nitrogen to facilitate dehydration. Instead, the reaction forms an enamine. The mechanism involves nucleophilic attack, followed by proton transfer and elimination of water, resulting in a compound with a double bond adjacent to the nitrogen atom.
The enamine product for part (b) will have the general structure: \( \text{C}_5\text{H}_7=\text{CH}-\text{N}(-\text{CH}_2\text{CH}_3)_2 \). This structure arises from the alpha-hydrogen of cyclopentanone being removed during the enamine formation process.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nucleophilic Addition
Nucleophilic addition is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophilic carbon atom, typically found in carbonyl compounds like ketones and aldehydes. In the case of cyclopentanone reacting with amines, the nitrogen atom of the amine acts as the nucleophile, attacking the carbonyl carbon, leading to the formation of an intermediate that can further react to form an imine or amine product.
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Nucleophilic Addition
Acid-Base Catalysis
In the presence of a trace amount of acid, acid-base catalysis can facilitate the reaction between cyclopentanone and amines. The acid can protonate the carbonyl oxygen, increasing the electrophilicity of the carbonyl carbon, making it more susceptible to nucleophilic attack by the amine. This process can enhance the rate of reaction and influence the products formed.
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Imine Formation
Imine formation is a specific reaction that occurs when a primary amine reacts with a carbonyl compound, resulting in the creation of an imine. In the reactions involving cyclopentanone and ethylamine or diethylamine, the nucleophilic attack leads to the formation of a tetrahedral intermediate, which can lose water to yield an imine. The nature of the amine can affect the stability and reactivity of the resulting imine.
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Related Practice
Textbook Question
Imines can exist as stereoisomers. The isomers are named using the E,Z system of nomenclature (Section 4.2 ). The lone pair has the lowest priority.
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Draw the structure of each of the following compounds:
a. the (E)-hydrazone of benzaldehyde
b. the (Z)-oxime of propiophenone
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Textbook Question
The compounds commonly known as 'amino acids' are actually α-aminocarboxylic-aminocarboxylic acids. What carbonyl compounds should be used to synthesize the two amino acids shown here?
a.
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Textbook Question
Why is the pKa value of protonated hydroxylamine (6.0) so much lower than the value of a protonated primary amine such as protonated methylamine (10.7)?
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Textbook Question
The pKa of protonated acetone is about –7.5 and the pKa of protonated hydroxylamine is 6.0.
a. In a reaction with hydroxylamine at pH 4.5 (Figure 16.2), what fraction of acetone is present in its acidic, protonated form?
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Textbook Question
The compounds commonly known as 'amino acids' are actually α-aminocarboxylic-aminocarboxylic acids. What carbonyl compounds should be used to synthesize the two amino acids shown here?
b.
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