Textbook Question
b. Explain why the rate of aminolysis of an ester cannot be increased by H+.
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Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 15 - Reactions of Carboxylic Acids and Carboxylic Acid DerivativesProblem 27
Bruice 8th EditionCh. 15 - Reactions of Carboxylic Acids and Carboxylic Acid DerivativesProblem 27Chapter 16, Problem 27
Write the mechanism for the acid-catalyzed reaction of tert-butyl acetate with methanol.
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Protonation of the carbonyl oxygen: The reaction begins with the protonation of the carbonyl oxygen in tert-butyl acetate by the acid catalyst (H⁺). This increases the electrophilicity of the carbonyl carbon, making it more susceptible to nucleophilic attack. The structure of the protonated intermediate can be represented as: .
Nucleophilic attack by methanol: Methanol (CH₃OH) acts as a nucleophile and attacks the electrophilic carbonyl carbon of the protonated ester. This forms a tetrahedral intermediate where the carbonyl oxygen now bears a positive charge.
Proton transfer: A proton transfer occurs within the tetrahedral intermediate to stabilize the structure. The hydroxyl group (OH) formed from the methanol attack is deprotonated, while the leaving group (tert-butoxide) is protonated to prepare for its departure.
Elimination of the leaving group: The protonated tert-butoxide group (tert-butyl alcohol) leaves, resulting in the formation of a new ester bond between the carbonyl carbon and the methanol oxygen. This step regenerates the acid catalyst (H⁺).
Final product formation: The final product of the reaction is methyl acetate (CH₃COOCH₃) and tert-butyl alcohol (C₄H₁₀O). The acid catalyst is regenerated, allowing the reaction to proceed catalytically.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acid-Catalyzed Reactions
Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In these reactions, the acid donates a proton (H+) to a reactant, enhancing its electrophilicity and facilitating nucleophilic attack. This mechanism is crucial in esterification and hydrolysis reactions, where the presence of an acid can significantly alter the reaction pathway and products.
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Acid Catalyzed
Nucleophilic Substitution Mechanism
Nucleophilic substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophile, resulting in the replacement of a leaving group. In the case of tert-butyl acetate reacting with methanol, methanol acts as the nucleophile, attacking the carbonyl carbon of the acetate. Understanding this mechanism is essential for predicting the outcome of the reaction and the stability of intermediates formed during the process.
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01:47Nucleophiles and Electrophiles can react in Substitution Reactions.
Ester Hydrolysis
Ester hydrolysis is the process by which an ester reacts with water (or an alcohol) to form an alcohol and a carboxylic acid. In acid-catalyzed hydrolysis, the ester is protonated, making it more susceptible to nucleophilic attack by water or alcohol. This reaction is important in organic synthesis and biochemistry, as it illustrates the reversible nature of ester formation and breakdown, which is key in many biological processes.
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Related Practice
Textbook Question
Write the mechanism for the acid-catalyzed transesterification of ethyl acetate with methanol.
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Textbook Question
D. N. Kursanov, a Russian chemist, proved that the bond that is broken in the hydroxide-ion-promoted hydrolysis of an ester is the acyl C—O bond, rather than the alkyl C—O bond, by studying the hydrolysis of the following ester under basic conditions:
a. What products contained the 18O label?
b. What product would have contained the 18O label if the alkyl C—O bond had broken?
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Textbook Question
Show the mechanism for the acid-catalyzed formation of 23c starting with the product obtained from its hydrolysis.
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Textbook Question
b. Explain why the rate of aminolysis of an ester cannot be increased by HO−, or RO−.
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Textbook Question
What products are obtained from the following reactions? b. phenyl acetate + excess ethanol + HCl
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