Textbook Question
Amino acids exist predominantly in one of the following forms. Which is it? Explain your answer.
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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 70a
Using pKa values for the conjugate acids of the bases on each side of the reaction arrow, identify which side of the equilibrium would be favored in the following hypothetical reactions.
(a) 
Verified step by step guidance1
Step 1: Identify the bases and conjugate acids on both sides of the equilibrium. On the left side, the base is the acetate ion (CH3COO⁻), and the conjugate acid is the alkyl bromide (CH3CHBrCH3). On the right side, the base is bromide ion (Br⁻), and the conjugate acid is the ester (CH3COOCH(CH3)2).
Step 2: Recall that the equilibrium position is determined by the relative strengths of the acids and bases. Use the pKa values of the conjugate acids to assess their relative acidity. The conjugate acid of CH3COO⁻ is acetic acid (CH3COOH), which has a pKa of approximately 4.76. The conjugate acid of Br⁻ is HBr, which has a pKa of approximately -9.
Step 3: Compare the pKa values. Acetic acid (pKa ≈ 4.76) is much weaker as an acid compared to HBr (pKa ≈ -9). This means that the acetate ion (CH3COO⁻) is a stronger base than Br⁻.
Step 4: The equilibrium will favor the side with the weaker acid and weaker base. Since acetic acid is weaker than HBr, the equilibrium will favor the side with acetic acid and bromide ion (right side).
Step 5: Conclude that the equilibrium is shifted toward the products (right side) because the conjugate acid (acetic acid) on the right side is weaker than the conjugate acid (HBr) on the left side.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
pKₐ and Acid-Base Equilibrium
pKₐ is a measure of the strength of an acid in solution; it is the negative logarithm of the acid dissociation constant (Kₐ). In acid-base reactions, the equilibrium position can be predicted by comparing the pKₐ values of the acids involved. The side with the weaker acid (higher pKₐ) is favored, as it indicates a lower tendency to donate protons, thus stabilizing the equilibrium.
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Determining Acid/Base Equilibrium
Conjugate Acids and Bases
In acid-base chemistry, a conjugate acid is formed when a base accepts a proton (H⁺), while a conjugate base is what remains after an acid donates a proton. Understanding the relationship between acids and their conjugate bases is crucial for predicting the direction of equilibrium in reactions. The strength of the conjugate acid or base influences the overall reaction dynamics.
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02:11Equilibrium constant and conjugates.
Le Chatelier's Principle
Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. This principle can be applied to predict how changes in concentration, pressure, or temperature will affect the position of equilibrium in acid-base reactions, particularly when considering the relative strengths of acids and bases.
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Related Practice
Textbook Question
Predict the product of the following Lewis acid–Lewis base reactions.
(c)
Textbook Question
Suggest a scheme by which N-methylmorpholine, salicylic acid, and naphthalene can be separated.
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Textbook Question
Using pKa values for the conjugate acids of the bases on each side of the reaction arrow, identify which side of the equilibrium would be favored in the following hypothetical reactions.
(c)
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Textbook Question
A medicinal chemist needed to deprotonate acetylene ( HC≡CH ) for use in a coupling reaction. Among the options given, which base(s) could be used for this process?
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Textbook Question
Predict the product of the following Lewis acid–Lewis base reactions.
(d) [an intramolecular reaction]
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