Textbook Question
Identify the nucleophile and the electrophile in each of the following reactions.
(b)
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Ch. 4 - Acids and Bases: Electron Flow
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
Chapter 3, Problem 53
The nitrogen screened in purple in Figure 4.43 is not protonated at physiological pH. Why?
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Step 1: Identify the nitrogen atom in question (screened in purple in Figure 4.43) and note its chemical environment. This nitrogen is part of an amine group attached to a carbon chain.
Step 2: Consider the physiological pH, which is typically around 7.4. At this pH, amines are generally protonated due to their basic nature. However, the protonation depends on the electron density around the nitrogen atom.
Step 3: Analyze the inductive effects of nearby substituents. In this molecule, fluorine atoms are present near the nitrogen. Fluorine is highly electronegative and pulls electron density away from the nitrogen through the inductive effect, reducing the nitrogen's ability to accept a proton.
Step 4: Examine the resonance or steric effects. In this case, there is no significant resonance stabilization or steric hindrance directly affecting the nitrogen, but the reduced electron density due to the fluorine atoms makes the nitrogen less basic.
Step 5: Conclude that the nitrogen screened in purple is not protonated at physiological pH because the inductive effect of the fluorine atoms decreases its basicity, making it less likely to accept a proton under these conditions.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Protonation
Protonation is the addition of a proton (H+) to a molecule, which can significantly alter its chemical properties. In organic chemistry, the protonation state of a molecule can affect its reactivity, solubility, and interaction with other molecules. Understanding the conditions under which protonation occurs, such as pH levels, is crucial for predicting the behavior of nitrogen-containing compounds.
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03:
Proton Splitting
Physiological pH
Physiological pH typically refers to the pH of human blood, which is around 7.4. At this pH, certain functional groups, including amines, may exist in their deprotonated form, affecting their charge and reactivity. Recognizing the significance of physiological pH helps in understanding the protonation states of biomolecules in biological systems.
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02:15The pH scale vs. the pKa scale.
Basicity of Nitrogen
Nitrogen is a basic atom due to its lone pair of electrons, which can accept protons. However, the basicity can be influenced by the surrounding molecular environment and the presence of other functional groups. In the context of the question, the nitrogen's basicity at physiological pH determines whether it remains unprotonated, which is essential for understanding its role in biological molecules.
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1:57Nitrogenous Bases Example 2
Related Practice
Textbook Question
Identify the most acidic proton in each pair. Tell which structural features you analyzed and why you weighted them as you did in picking one answer. [Always start by drawing the conjugate base.]
(d)
1130
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Textbook Question
Identify the nucleophile and the electrophile in each of the following reactions.
(a)
1149
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Textbook Question
Identify the most acidic proton in each pair. Tell which structural features you analyzed and why you weighted them as you did in picking one answer. [Always start by drawing the conjugate base.]
(b)
828
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Textbook Question
Identify the most acidic proton in each pair. Tell which structural features you analyzed and why you weighted them as you did in picking one answer. [Always start by drawing the conjugate base.]
(h)
1630
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Textbook Question
Identify the Lewis acid and the Lewis base in each of the following reactions.
(c)
1504
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