Textbook Question
Rank the amines in each set in order of increasing basicity.
(e)
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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 33a
Rank the amines in each set in order of increasing basicity.
(a) 
Verified step by step guidance1
Step 1: Understand the concept of basicity in amines. Basicity refers to the ability of a compound to donate a lone pair of electrons to a proton (H⁺). Amines are basic because the nitrogen atom has a lone pair of electrons that can accept a proton.
Step 2: Analyze the structures provided. The first amine is an aniline (benzene ring with an NH₂ group), the second is cyclohexylamine (cyclohexane ring with an NH₂ group), and the third is diphenylamine (two benzene rings attached to an NH group).
Step 3: Consider the electronic effects of the groups attached to the nitrogen atom. In aniline, the lone pair on nitrogen is partially delocalized into the aromatic ring, reducing its availability to accept a proton and thus decreasing basicity. In cyclohexylamine, the nitrogen's lone pair is not delocalized, making it more available for protonation and increasing basicity. In diphenylamine, the lone pair is partially delocalized into both aromatic rings, further reducing basicity compared to aniline.
Step 4: Rank the amines based on their basicity. Cyclohexylamine is the most basic because its nitrogen lone pair is fully available for protonation. Aniline is less basic due to partial delocalization of the lone pair into the aromatic ring. Diphenylamine is the least basic because the lone pair is delocalized into two aromatic rings.
Step 5: Final ranking in order of increasing basicity: Diphenylamine < Aniline < Cyclohexylamine.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Basicity of Amines
Basicity in amines refers to their ability to accept protons (H+) from acids. This property is influenced by the availability of the lone pair of electrons on the nitrogen atom, which can bond with protons. Factors such as steric hindrance and the presence of electron-donating or withdrawing groups can significantly affect the basicity of different amines.
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Reductive Amination
Inductive Effect
The inductive effect describes how the presence of electronegative atoms or groups near the nitrogen atom in an amine can influence its basicity. Electron-withdrawing groups decrease basicity by stabilizing the lone pair on nitrogen, making it less available for protonation. Conversely, electron-donating groups enhance basicity by increasing the electron density around the nitrogen, facilitating proton acceptance.
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01:47Understanding the Inductive Effect.
Steric Hindrance
Steric hindrance refers to the spatial arrangement of atoms around the nitrogen atom in an amine, which can impede the approach of protons. Bulky substituents can create steric barriers that reduce the amine's ability to accept protons, thereby decreasing its basicity. Understanding the steric effects is crucial when ranking amines based on their basicity.
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Related Practice
Textbook Question
For each compound,
(1) classify the nitrogen-containing functional groups.
(2) provide an acceptable name.
(a)
(b)
(c)
1020
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Textbook Question
For each compound,
(1) classify the nitrogen-containing functional groups.
(2) provide an acceptable name.
(g)
(h)
1618
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Textbook Question
Rank the amines in each set in order of increasing basicity.
(c)
944
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Textbook Question
Rank the amines in each set in order of increasing basicity.
(d)
819
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Textbook Question
Show how to prepare the following aromatic amines by aromatic nitration, followed by reduction. You may use benzene and toluene as your aromatic starting materials.
(d) m-aminobenzoic acid
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