Textbook Question
Draw the mechanism for the last step in the Kiliani-Fischer synthesis.
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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 42c
Peroxyacetic acid (bp = 105 °C) has a lower boiling point than acetic acid (bp = 118 °C), even though peroxyacetic acid has a higher molecular weight. Explain why peroxyacetic acid is more volatile than acetic acid.
Verified step by step guidance1
Understand the concept of boiling point: The boiling point of a substance is the temperature at which its vapor pressure equals the atmospheric pressure, allowing it to transition from liquid to gas.
Consider the molecular structure: Acetic acid (CH₃COOH) and peroxyacetic acid (CH₃COOOH) have similar structures, but peroxyacetic acid contains an additional oxygen atom, forming a peroxide linkage.
Analyze intermolecular forces: Acetic acid can form strong hydrogen bonds due to the presence of the hydroxyl group (OH) and the carbonyl group (C=O), which contribute to its higher boiling point.
Evaluate the effect of the peroxide linkage: The peroxide linkage in peroxyacetic acid (O-O bond) is less effective at hydrogen bonding compared to the carbonyl group in acetic acid, resulting in weaker intermolecular forces.
Conclude the volatility: Due to weaker hydrogen bonding in peroxyacetic acid, it has a lower boiling point and is more volatile than acetic acid, despite having a higher molecular weight.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydrogen Bonding
Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen or nitrogen. Acetic acid can form more extensive hydrogen bonds due to its carboxylic acid group, which increases its boiling point compared to peroxyacetic acid, which has a less effective hydrogen bonding capability due to the presence of the peroxide group.
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Molecular Structure
The molecular structure of a compound affects its physical properties, including boiling point. Peroxyacetic acid contains a peroxide linkage, which alters its ability to form hydrogen bonds compared to acetic acid. This structural difference results in weaker intermolecular forces in peroxyacetic acid, making it more volatile despite its higher molecular weight.
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Intermolecular Forces
Intermolecular forces, such as hydrogen bonding, dipole-dipole interactions, and van der Waals forces, determine the boiling point of a substance. Acetic acid's stronger hydrogen bonding leads to higher boiling points, while peroxyacetic acid's weaker intermolecular forces due to its peroxide group result in increased volatility and a lower boiling point.
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Related Practice
Textbook Question
Two of the methods for converting alkyl halides to carboxylic acids are covered in Sections 20-8B and 20-8C. One is formation of a Grignard reagent followed by addition of carbon dioxide and then dilute acid. The other is substitution by cyanide ion, followed by hydrolysis of the resulting nitrile. For each of the following conversions, decide whether either or both of these methods would work, and explain why. Show the reactions you would use.
(a)
(b)
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Textbook Question
In the presence of a trace of acid, δ-hydroxyvaleric acid forms a cyclic ester (lactone).
(a) Give the structure of the lactone, called δ-valerolactone.
(b) Propose a mechanism for the formation of δ-valerolactone.
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Textbook Question
The following NMR spectra correspond to compound of formula (C) C6H10O2. Propose structure, and show how it is consistent with the observed absorptions.
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Textbook Question
Two of the methods for converting alkyl halides to carboxylic acids are covered in Sections 20-8B and 20-8C. One is formation of a Grignard reagent followed by addition of carbon dioxide and then dilute acid. The other is substitution by cyanide ion, followed by hydrolysis of the resulting nitrile. For each of the following conversions, decide whether either or both of these methods would work, and explain why. Show the reactions you would use.
(e)
(f)
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Textbook Question
The following NMR spectra correspond to compound of formula (A) C9H10O2. Propose structure, and show how it is consistent with the observed absorptions.
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