Textbook Question
Show how you would accomplish the following syntheses efficiently (you may use any necessary reagents).
(a) trans-1-bromobut-2-ene → trans-pent-3-enoic acid (two ways)
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Ch. 20 - Carboxylic Acids
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 20, Problem 32
Arrange each group of compounds in order of increasing acidity.
(a) phenol, ethanol, acetic acid
(b) p-toluenesulfonic acid, acetic acid, chloroacetic acid
(c) benzoic acid, o-nitrobenzoic acid, m-nitrobenzoic acid
(d) butyric acid, α-bromobutyric acid, β-bromobutyric acid
(e) 
Verified step by step guidance1
Step 1: Understand the concept of acidity. Acidity is influenced by the ability of a compound to donate a proton (H⁺). Factors such as electronegativity, inductive effects, resonance, and the stability of the conjugate base play a role in determining acidity.
Step 2: Analyze the substituents attached to the carboxylic acid group in each compound. Electronegative substituents like F, Cl, and Br exert an inductive effect, pulling electron density away from the carboxylic acid group, stabilizing the conjugate base, and increasing acidity.
Step 3: Compare the electronegativity of the halogens (F, Cl, Br). Fluorine is the most electronegative, followed by chlorine, and then bromine. Therefore, the inductive effect is strongest for fluorine, making the compound with the fluorine substituent the most acidic.
Step 4: Consider the proximity of the halogen to the carboxylic acid group. All three compounds have the halogen directly attached to the carbon adjacent to the carboxylic acid group, so the inductive effect is comparable in terms of distance.
Step 5: Arrange the compounds in order of increasing acidity based on the electronegativity of the halogen substituents: the bromine-substituted compound is the least acidic, followed by the chlorine-substituted compound, and the fluorine-substituted compound is the most acidic.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acidity and pKa
Acidity in organic chemistry refers to the tendency of a compound to donate a proton (H+). The strength of an acid is often measured by its pKa value; lower pKa values indicate stronger acids. Understanding the relationship between structure and acidity is crucial, as factors like electronegativity and resonance can significantly influence a compound's ability to release a proton.
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Identifying pKa values
Resonance Stabilization
Resonance stabilization occurs when a molecule can be represented by multiple valid Lewis structures, allowing for the delocalization of electrons. This delocalization can stabilize the conjugate base formed after deprotonation, thereby increasing the acidity of the original compound. For example, carboxylic acids benefit from resonance, making them generally more acidic than alcohols.
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03:43The radical stability trend.
Inductive Effect
The inductive effect refers to the electron-withdrawing or electron-donating effects of substituents on a molecule, which can influence acidity. Electronegative atoms or groups near the acidic proton can stabilize the negative charge of the conjugate base through inductive withdrawal, enhancing acidity. For instance, the presence of halogens in carboxylic acids can increase their acidity compared to their unsubstituted counterparts.
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01:47Understanding the Inductive Effect.
Related Practice
Textbook Question
Predict the products (if any) of the following acid–base reactions.
(d) α-bromopropionic acid + sodium propionate
(e) benzoic acid + sodium phenoxide
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Textbook Question
Predict the products (if any) of the following acid–base reactions.
(a) acetic acid + ammonia
(b) phthalic acid + excess NaOH
(c) p-toluic acid + potassium trifluoroacetate
Textbook Question
Given the structure of ascorbic acid (vitamin C):
(a) Is ascorbic acid a carboxylic acid?
(b) Compare the acid strength of ascorbic acid (pKa = 4.71) with acetic acid.
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Textbook Question
Given the structure of ascorbic acid (vitamin C):
(c) Predict which proton in ascorbic acid is the most acidic.
(d) Draw the form of ascorbic acid that is present in the body (aqueous solution, pH = 7.4)
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Textbook Question
Rank the following isomers in order of increasing boiling point, and explain the reasons for your order of ranking.
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