Textbook Question
Which ester hydrolyzes more rapidly? a. methyl acetate or phenyl acetate?
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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 19b
Bruice 8th EditionCh. 15 - Reactions of Carboxylic Acids and Carboxylic Acid DerivativesProblem 19bChapter 16, Problem 19b
Which ester hydrolyzes more rapidly? b. phenyl acetate or benzyl acetate?
Verified step by step guidance1
Step 1: Understand the hydrolysis mechanism for esters. Ester hydrolysis typically occurs via nucleophilic attack by water or hydroxide ions on the carbonyl carbon, leading to the cleavage of the ester bond.
Step 2: Analyze the chemical structures of phenyl acetate and benzyl acetate. Phenyl acetate has the phenyl group directly attached to the oxygen atom of the ester, while benzyl acetate has a benzyl group (a phenyl group attached to a CH2 group) attached to the oxygen atom.
Step 3: Consider the electronic effects of the substituents. The phenyl group in phenyl acetate can stabilize the transition state through resonance, making the carbonyl carbon less electrophilic and slowing down hydrolysis. In benzyl acetate, the benzyl group does not directly interact with the carbonyl carbon, so the hydrolysis rate is less affected by resonance stabilization.
Step 4: Evaluate steric effects. The phenyl group in phenyl acetate is bulkier and closer to the carbonyl carbon, which can hinder the approach of nucleophiles and slow down hydrolysis. Benzyl acetate has less steric hindrance near the carbonyl carbon, allowing nucleophiles to attack more easily.
Step 5: Conclude based on the above factors. Benzyl acetate is expected to hydrolyze more rapidly than phenyl acetate due to reduced resonance stabilization and steric hindrance near the carbonyl carbon.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Ester Hydrolysis
Ester hydrolysis is a chemical reaction where an ester reacts with water to form an alcohol and a carboxylic acid. This reaction can occur under acidic or basic conditions and is important in organic chemistry for understanding the reactivity of esters. The rate of hydrolysis can be influenced by the structure of the ester, including steric hindrance and electronic effects.
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Steric Effects
Steric effects refer to the influence of the spatial arrangement of atoms in a molecule on its reactivity. In the context of ester hydrolysis, bulky groups near the ester bond can hinder the approach of water molecules, slowing down the reaction. Benzyl acetate has a benzyl group that is less sterically hindered compared to the phenyl group in phenyl acetate, potentially affecting the rate of hydrolysis.
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Electronic Effects
Electronic effects involve the influence of electron distribution within a molecule on its chemical behavior. In esters, the presence of electron-donating or electron-withdrawing groups can stabilize or destabilize the transition state during hydrolysis. The benzyl group in benzyl acetate can provide resonance stabilization, which may enhance the hydrolysis rate compared to phenyl acetate, where the phenyl group does not offer the same stabilization.
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Related Practice
Textbook Question
Write a mechanism for each of the following reactions:
a. the uncatalyzed hydrolysis of methyl propionate.
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Textbook Question
Using the mechanism for the acid-catalyzed hydrolysis of an ester as your guide, write the mechanism—showing all the curved arrows—for the acid-catalyzed reaction of acetic acid and methanol to form methyl acetate. Use HB+ and :B to represent the proton-donating and proton-removing species, respectively.
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Textbook Question
Write a mechanism for each of the following reactions:
b. the aminolysis of phenyl formate, using methylamine.
Textbook Question
In the mechanism for the acid-catalyzed hydrolysis of an ester,
c. what species is HB+ most likely to be in the hydrolysis reaction?
d. what species is HB+ most likely to be in the reverse reaction?
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Textbook Question
What products are formed from the acid-catalyzed hydrolysis of the following esters?
a.
b.
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