Textbook Question
Within each structure, rank the indicated nitrogens by increasing basicity.
(a)
(b)
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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 33e
Rank the amines in each set in order of increasing basicity.
(e) 
Verified step by step guidance1
Step 1: Identify the functional groups attached to the benzene ring in each compound. The first compound has an amino group (-NH2), the second compound has a methylamino group (-CH2NH2), and the third compound has an amide group (-CONH2).
Step 2: Understand the basicity of each functional group. Amines (-NH2 and -CH2NH2) are generally basic because the nitrogen atom has a lone pair of electrons that can accept a proton. Amides (-CONH2), on the other hand, are less basic because the lone pair on the nitrogen is delocalized into the carbonyl group, reducing its availability to accept a proton.
Step 3: Consider the effect of the benzene ring on basicity. In the first compound, the amino group (-NH2) is directly attached to the benzene ring, which can reduce its basicity due to resonance effects. The lone pair on the nitrogen can delocalize into the aromatic ring, making it less available for protonation. In the second compound, the methylamino group (-CH2NH2) is not directly attached to the benzene ring, so resonance effects are absent, and the nitrogen remains more basic.
Step 4: Compare the basicity of the amide group (-CONH2) in the third compound. The amide group is the least basic because the nitrogen's lone pair is delocalized into the carbonyl group, making it significantly less available for protonation compared to the amino groups in the first and second compounds.
Step 5: Rank the compounds in order of increasing basicity based on the above analysis. The amide group (-CONH2) is the least basic, followed by the amino group (-NH2) directly attached to the benzene ring, and the methylamino group (-CH2NH2) is the most basic.
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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+) in a chemical reaction. This property is influenced by the availability of the lone pair of electrons on the nitrogen atom, which can bond with protons. Generally, the more electron-donating groups attached to the nitrogen, the higher the basicity, as they increase the electron density on the nitrogen.
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Reductive Amination
Inductive Effect
The inductive effect describes how the presence of electronegative atoms or groups near a functional group can influence its properties, including basicity. Electron-withdrawing groups decrease electron density on the nitrogen, making it less basic, while electron-donating groups enhance basicity by increasing electron density. Understanding this effect is crucial for ranking the basicity of different amines.
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01:47Understanding the Inductive Effect.
Steric Hindrance
Steric hindrance refers to the repulsion between bulky groups in a molecule that can affect its reactivity and basicity. In amines, larger substituents around the nitrogen can hinder the approach of protons, reducing the amine's basicity. Thus, when ranking amines, considering the size and steric effects of substituents is essential for accurate comparisons.
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02:53Understanding steric effects.
Related Practice
Textbook Question
Rank the amines in each set in order of increasing basicity.
(a)
857
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Textbook Question
Within each structure, rank the indicated nitrogens by increasing basicity.
(d)
(e)
996
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Textbook Question
Within each structure, rank the indicated nitrogens by increasing basicity.
(c)
1230
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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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