Textbook Question
Which of the following compounds are capable of being resolved into enantiomers?
(a) N-ethyl-N-methylaniline
(b) 2-methylpiperidine
(c) 1-methylpiperidine
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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 35a,b
In each pair of compounds, select the stronger base, and explain your choice.
(a) HOCH2CH2NH2 or CH3CH2NH2
(b) PhNH2 or PhCH2NH2
Verified step by step guidance1
Step 1: Understand the concept of basicity. Basicity refers to the ability of a compound to donate a lone pair of electrons to accept a proton (H⁺). Stronger bases are better at donating their lone pair of electrons.
Step 2: Analyze part (a): Compare HOCH₂CH₂NH₂ and CH₃CH₂NH₂. The presence of the hydroxyl group (-OH) in HOCH₂CH₂NH₂ introduces an electron-withdrawing effect through inductive effects, which reduces the electron density on the nitrogen atom, making it less available to donate its lone pair. In contrast, CH₃CH₂NH₂ lacks this electron-withdrawing group, so its nitrogen atom has a higher electron density and is a stronger base.
Step 3: Analyze part (b): Compare PhNH₂ (aniline) and PhCH₂NH₂ (benzylamine). In PhNH₂, the lone pair of electrons on the nitrogen atom can delocalize into the aromatic ring through resonance, reducing its availability to accept a proton. In PhCH₂NH₂, the nitrogen atom is not directly attached to the aromatic ring, so its lone pair is not delocalized and remains more available for protonation, making it a stronger base.
Step 4: Summarize the reasoning for each pair: For (a), CH₃CH₂NH₂ is the stronger base because it lacks the electron-withdrawing -OH group. For (b), PhCH₂NH₂ is the stronger base because its nitrogen's lone pair is not delocalized into the aromatic ring.
Step 5: To confirm your understanding, consider the structural features that influence basicity, such as inductive effects, resonance effects, and the availability of the lone pair of electrons on the nitrogen atom for protonation.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Basicity
Basicity refers to the ability of a compound to accept protons (H+) or donate electron pairs. In organic chemistry, stronger bases are typically those that can stabilize the positive charge that results from protonation. Factors influencing basicity include the availability of lone pairs, steric hindrance, and the stability of the resulting conjugate acid.
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06:21
Understanding the difference between basicity and nucleophilicity.
Inductive Effect
The inductive effect describes the electron-withdrawing or electron-donating effects of substituents on a molecule. Electron-donating groups, such as alkyl groups, can increase basicity by stabilizing the positive charge on the conjugate acid, while electron-withdrawing groups, like phenyl groups, can decrease basicity by destabilizing the conjugate acid.
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01:47Understanding the Inductive Effect.
Resonance
Resonance is a concept that explains the delocalization of electrons in a molecule, which can affect its stability and reactivity. In the context of basicity, resonance can stabilize or destabilize the conjugate acid formed after protonation. For example, if a lone pair is involved in resonance with an aromatic system, it may be less available for protonation, thus reducing basicity.
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Related Practice
Textbook Question
Within each structure, rank the indicated nitrogens by increasing basicity.
(d)
(e)
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Textbook Question
Within each structure, rank the indicated nitrogens by increasing basicity.
(f)
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Textbook Question
Within each structure, rank the indicated nitrogens by increasing basicity.
(c)
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Textbook Question
Which of the following compounds are capable of being resolved into enantiomers?
(d) 1,2,2-trimethylaziridine
(e)
(f)
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Textbook Question
In each pair of compounds, select the stronger base, and explain your choice.
(c)
(d)
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