Textbook Question
Show how you would use acetic anhydride and an appropriate alcohol or amine to synthesize (i) benzyl acetate and (ii) N,N-diethylacetamide.
Ch. 21 - Carboxylic Acid Derivatives
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 21, Problem 11
Propose a mechanism for the reaction of benzyl acetate with methylamine. Label the attacking nucleophile and the leaving group, and draw the transition state in which the leaving group leaves.
Verified step by step guidance1
Step 1: Identify the functional groups in benzyl acetate. Benzyl acetate is an ester, which contains a carbonyl group (C=O) bonded to an oxygen atom. Methylamine (CH3NH2) is an amine and acts as a nucleophile due to the lone pair of electrons on the nitrogen atom.
Step 2: Recognize the nucleophilic attack. Methylamine (CH3NH2) will act as the attacking nucleophile, targeting the electrophilic carbon of the carbonyl group in benzyl acetate. The lone pair on the nitrogen of methylamine will attack the carbonyl carbon, forming a tetrahedral intermediate.
Step 3: Label the leaving group. In this reaction, the leaving group is the acetate ion (CH3COO−), which is formed when the bond between the carbonyl carbon and the oxygen of the ester breaks during the reaction.
Step 4: Draw the transition state. The transition state involves partial bonds between the nucleophile (methylamine) and the carbonyl carbon, as well as partial bonds between the carbonyl carbon and the leaving group (acetate ion). This state represents the point of highest energy during the reaction.
Step 5: Complete the mechanism. After the transition state, the tetrahedral intermediate collapses, expelling the acetate ion as the leaving group and forming the final product, which is benzyl methylamide. Ensure to show all curved arrows indicating electron movement throughout the mechanism.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nucleophilic Substitution Mechanism
Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophile, resulting in the replacement of a leaving group. In the case of benzyl acetate reacting with methylamine, methylamine acts as the nucleophile, attacking the carbon atom bonded to the acetate group. Understanding this mechanism is crucial for predicting the outcome of the reaction and the stability of intermediates.
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Leaving Groups
A leaving group is an atom or group that can depart from the parent molecule during a chemical reaction, taking with it the electrons that were shared with the parent. In the reaction of benzyl acetate, the acetate group (-OAc) serves as the leaving group. The ability of a leaving group to stabilize the negative charge after departure is key to the reaction's feasibility and rate.
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Transition State
The transition state is a high-energy, unstable arrangement of atoms that occurs during a chemical reaction, representing the point at which reactants are transformed into products. In the context of the reaction between benzyl acetate and methylamine, drawing the transition state involves illustrating the moment when the nucleophile is forming a bond with the carbon atom while the leaving group is departing. This concept is essential for understanding the energy profile and kinetics of the reaction.
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Related Practice
Textbook Question
Show how you would use appropriate acyl chlorides and amines to synthesize the following amides.
(c) cyclohexanecarboxamide
(d)
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Textbook Question
When ethyl 4-hydroxybutyrate is heated in the presence of a trace of a basic catalyst (sodium acetate), one of the products is a lactone. Propose a mechanism for formation of this lactone.
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Textbook Question
Show how you would use appropriate acyl chlorides and amines to synthesize the following amides.
(a) N,N-dimethylacetamide
(b) acetanilide (PhNHCOCH3)
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Textbook Question
Propose a mechanism for the acid-catalyzed hydrolysis of phenylalanine ethyl ester.
Textbook Question
Acid-catalyzed transesterification:
Complete the mechanism for this acid-catalyzed transesterification by drawing out all the individual steps. Draw the important resonance contributors for each resonance-stabilized intermediate.
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