Textbook Question
When cyclodecane-1,6-dione is treated with sodium carbonate, the product gives a UV spectrum similar to that of 1-acetyl-2-methylcyclopentene. Propose a structure for the product, and give a mechanism for its formation.
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Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds
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
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Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 32a
Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 32aChapter 22, Problem 32a
Show how each compound can be dissected into reagents joined by an aldol condensation, then decide whether the necessary aldol condensation is feasible.
(a) 
Verified step by step guidance1
Step 1: Analyze the given compound structure. The compound contains an aldehyde group (-CHO) and a hydroxyl group (-OH) on adjacent carbons, indicating it could be the product of an aldol condensation reaction.
Step 2: Recall the general mechanism of aldol condensation. It involves the reaction of two carbonyl compounds (aldehydes or ketones) in the presence of a base to form a β-hydroxy carbonyl compound. The β-hydroxy carbonyl compound can further undergo dehydration to form an α,β-unsaturated carbonyl compound.
Step 3: Identify the two carbonyl compounds that could combine to form the given compound. The aldehyde group (-CHO) and the hydroxyl group (-OH) suggest that one reagent must provide the aldehyde functionality, while the other reagent must provide the enolate ion that attacks the aldehyde.
Step 4: Dissect the compound into its possible precursors. The aldehyde group (-CHO) likely comes from a simple aldehyde, such as butanal (CH₃CH₂CH₂CHO). The enolate ion could be derived from a ketone, such as 2-ethylpentan-3-one (CH₃CH₂CH₂COCH₂CH₂CH₃), which forms the enolate at the α-carbon adjacent to the carbonyl group.
Step 5: Evaluate the feasibility of the aldol condensation. The reaction is feasible because both precursors (butanal and 2-ethylpentan-3-one) can form stable intermediates under basic conditions. The enolate ion from the ketone can attack the aldehyde to form the β-hydroxy carbonyl compound, which matches the structure of the given compound.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Aldol Condensation
Aldol condensation is a reaction between aldehydes or ketones that contain alpha-hydrogens, leading to the formation of β-hydroxy aldehydes or ketones. This reaction involves the nucleophilic addition of an enolate ion to a carbonyl compound, followed by dehydration to yield an α,β-unsaturated carbonyl compound. Understanding this process is crucial for dissecting compounds into their respective reagents.
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Enolate Ion Formation
Enolate ions are formed when a base abstracts an alpha-hydrogen from a carbonyl compound, resulting in a resonance-stabilized anion. This ion acts as a nucleophile in aldol reactions, allowing it to attack another carbonyl carbon. Recognizing how to generate enolate ions from the given compounds is essential for determining the feasibility of the aldol condensation.
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Feasibility of Aldol Condensation
The feasibility of an aldol condensation depends on the structural features of the reactants, such as the presence of alpha-hydrogens and the stability of the resulting products. Factors like steric hindrance and the ability to form stable enolate ions influence whether the reaction will proceed. Evaluating these aspects is necessary to conclude if the aldol condensation can occur for the given compounds.
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Related Practice
Textbook Question
Show how each compound can be dissected into reagents joined by an aldol condensation, then decide whether the necessary aldol condensation is feasible.
(e)
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Textbook Question
Show how each compound can be dissected into reagents joined by an aldol condensation, then decide whether the necessary aldol condensation is feasible.
(b)
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Textbook Question
Predict the major products of the following base-catalyzed aldol condensations with dehydration.
(b) 2,2-dimethylpropanal + acetophenone
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Textbook Question
Show how octane-2,7-dione might cyclize to a cycloheptenone. Explain why ring closure to the cycloheptenone is not favored.
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Textbook Question
Show how each compound can be dissected into reagents joined by an aldol condensation, then decide whether the necessary aldol condensation is feasible.
(c)
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