Textbook Question
Using cyclopentanone as the reactant, show the product of
b. an aldol addition.
c. an aldol condensation.
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Ch. 17 - Reactions at the Alpha-Carbon
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
Chapter 18, Problem 62
Show how the following compound can be synthesized from the given starting material. (Hint: Start with an acetoacetic ester.)
Verified step by step guidance1
Step 1: Begin with the acetoacetic ester (ethyl acetoacetate) as the starting material. Deprotonate the alpha hydrogen using a strong base such as sodium ethoxide (NaOEt) to form the enolate ion. This step is crucial for enabling nucleophilic attack in subsequent steps.
Step 2: Perform an alkylation reaction by reacting the enolate ion with an alkyl halide, such as 1-bromopentane, to introduce the pentyl group at the alpha position of the acetoacetic ester. This step uses the SN2 mechanism.
Step 3: Hydrolyze the ester group in the acetoacetic ester derivative using aqueous acid (H3O+) to convert it into a beta-keto acid. This step involves ester hydrolysis followed by decarboxylation.
Step 4: Decarboxylate the beta-keto acid by heating it. This removes the carboxyl group as CO2, leaving behind the desired ketone structure with the pentyl group attached.
Step 5: Combine the cyclohexanol starting material with the synthesized ketone. Oxidize cyclohexanol to cyclohexanone using an oxidizing agent such as PCC (pyridinium chlorochromate). Then, perform an aldol condensation between cyclohexanone and the synthesized ketone to form the final compound.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acetoacetic Ester Synthesis
Acetoacetic ester synthesis is a method used to create ketones from acetoacetic esters. This reaction involves the enolate ion of the acetoacetic ester reacting with an alkyl halide, followed by hydrolysis and decarboxylation. Understanding this process is crucial for synthesizing complex organic compounds, as it allows for the introduction of various alkyl groups to the carbon skeleton.
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Enolate Chemistry
Enolates are reactive intermediates formed from the deprotonation of carbonyl compounds, such as ketones and esters. They play a key role in nucleophilic addition reactions, allowing for the formation of new carbon-carbon bonds. Mastery of enolate chemistry is essential for understanding how to manipulate starting materials in organic synthesis, particularly in the context of acetoacetic ester reactions.
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Decarboxylation
Decarboxylation is the process of removing a carboxyl group from a molecule, typically resulting in the release of carbon dioxide. This reaction is often used in organic synthesis to simplify structures and increase the carbon chain length. Recognizing when and how to apply decarboxylation is vital for completing the synthesis of target compounds from acetoacetic esters.
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Related Practice
Textbook Question
There are other condensation reactions similar to the aldol and Claisen condensations:
a. The Perkin condensation is the condensation of an aromatic aldehyde and acetic anhydride. Draw the product obtained from the following Perkin condensation:
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Textbook Question
There are other condensation reactions similar to the aldol and Claisen condensations:
b. What compound is formed if water is added to the product of a Perkin condensation?
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Textbook Question
A β-ɣ-unsaturated carbonyl compound rearranges to a more stable conjugated ⍺,β-unsaturated compound in the presence of either acid or base. b. Propose a mechanism for the acid-catalyzed rearrangement.
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Textbook Question
Show how 4-methyl-3-hexanol can be synthesized from 3-pentanone.
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Textbook Question
Using cyclopentanone as the reactant, show the product of a. acid-catalyzed keto–enol interconversion.
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