Organic Chemistry
8th Edition
ISBN: 9781305580350
Author: William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote
Publisher: Cengage Learning
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Chapter 17, Problem 17.41P
(a)
Interpretation Introduction
Interpretation: Mechanism for the given type of decarboxylation reaction has to be proposed and it should be compared with the mechanism of decarboxylation of
Concept introduction:
Carboxylic acids contain a carbonyl attached to a hydroxyl group as shown below,
If
Decarboxylation of
The mechanism of thermal decarboxylation involves two processes,
- (i) Redistribution of electrons in a cyclic transition state.
- (ii) Cyclic transition state possesses keto-enol tautomerism.
(b)
Interpretation Introduction
Interpretation: Mechanism for the given type of decarboxylation reaction has to be proposed and it should be compared with the mechanism of decarboxylation of
Concept introduction:
Carboxylic acids contain a carbonyl attached to a hydroxyl group as shown below,
If carboxylic acid is heated to a very high temperature then of carbon dioxide will be eliminated from it this reaction is known as decarboxylation. Simple carboxylic acids do not decarboxylate readily.
Decarboxylation of
Simply the mechanism of thermal decarboxylation involves two processes,
- (i) Redistribution of electrons in a cyclic transition state.
- (ii) Cyclic transition state possesses keto-enol tautomerism.
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When heated, carboxylic salts in which there is a good leaving group on the carbon beta to the carboxylate group undergo decarboxylation/elimination to give an alkene.Propose a mechanism for this type of decarboxylation/elimination. Compare the mechanism of the decarboxylations with the mechanism for decarboxylation of b-ketoacids. In what way(s) are the mechanisms similar?
H3C
OH
1. Br2, PBг3
2. H₂O
H3C
OH
Br
The a-bromination of carbonyl compounds by Br₂ in acetic acid is limited to aldehydes and ketones because acids, esters, and amides don't enolize to a sufficient extent. Carboxylic acids, however, can
be a-brominated by first converting the carboxylic acid to an acid bromide by treatment with PBr3. Following enolization of the acid bromide, Br2 reacts in an a-substitution reaction. Hydrolysis of the
acid bromide completes the reaction.
Draw curved arrows to show the movement of electrons in this step of the mechanism.
Arrow-pushing Instructions
Br
Br
зь
P-Br
Br
H₂C
H₂C
SH
Br
Br
In the presence of an appropriate base, esters undergo self-condensation to afford the
corresponding B-ketoesters as shown below. Explain in detail using reaction schemes (not
mechanisms) why route C and not routes A and B would lead to the expected product.
2 x Ethyl acetate
A: NaOH(aq)
B: OMe-
C: OEt-
EtO
CH3
Chapter 17 Solutions
Organic Chemistry
Ch. 17.2 - Prob. 17.1PCh. 17.4 - Which is the stronger acid in each pair?Ch. 17.4 - Prob. 17.3PCh. 17.7 - Prob. 17.4PCh. 17.8 - Prob. 17.5PCh. 17.8 - Prob. AQCh. 17.8 - Prob. BQCh. 17.8 - Prob. CQCh. 17.8 - Permethrin and Bifenthrin Pyrethrin is a natural...Ch. 17.9 - Prob. 17.6P
Ch. 17 - Write the IUPAC name of each compound, showing...Ch. 17 - Prob. 17.8PCh. 17 - Prob. 17.9PCh. 17 - Prob. 17.10PCh. 17 - Prob. 17.11PCh. 17 - Prob. 17.12PCh. 17 - Prob. 17.13PCh. 17 - On a cyclohexane ring, an axial carboxyl group has...Ch. 17 - Prob. 17.15PCh. 17 - Prob. 17.16PCh. 17 - Prob. 17.17PCh. 17 - Complete each reaction.Ch. 17 - Prob. 17.19PCh. 17 - Prob. 17.20PCh. 17 - Prob. 17.21PCh. 17 - Show the reagents and experimental conditions...Ch. 17 - Prob. 17.23PCh. 17 - Prob. 17.24PCh. 17 - Prob. 17.25PCh. 17 - In each set, assign the acid its appropriate pKa.Ch. 17 - Low-molecular-weight dicarboxylic acids normally...Ch. 17 - Complete the following acid-base reactions. (a)...Ch. 17 - Prob. 17.29PCh. 17 - Prob. 17.30PCh. 17 - Excess ascorbic acid is excreted in the urine, the...Ch. 17 - Give the expected organic product when...Ch. 17 - Show how to convert trans-3-phenyl-2-propenoic...Ch. 17 - Show how to convert 3-oxobutanoic acid...Ch. 17 - Prob. 17.35PCh. 17 - Prob. 17.36PCh. 17 - Prob. 17.37PCh. 17 - When 4-hydroxybutanoic acid is treated with an...Ch. 17 - Fischer esterification cannot be used to prepare...Ch. 17 - Draw the product formed on thermal decarboxylation...Ch. 17 - Prob. 17.41PCh. 17 - Show how cyclohexanecarboxylic acid could be...Ch. 17 - Prob. 17.43PCh. 17 - Prob. 17.44PCh. 17 - Prob. 17.45PCh. 17 - Write the products of the following sequences of...Ch. 17 - Using your reaction roadmaps as a guide, show how...Ch. 17 - Using your reaction roadmaps as a guide, show how...Ch. 17 - Using your reaction roadmaps as a guide, show how...Ch. 17 - Using your reaction roadmaps as a guide, show how...Ch. 17 - Prob. 17.51PCh. 17 - Complete the following Fischer esterification...Ch. 17 - Prob. 17.53P
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