Textbook Question
Predict the reagents or reactant(s) necessary to complete the following syntheses.
(b)
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Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
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Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 9c
Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 9cChapter 16, Problem 9c
Predict the reagents or reactant(s) necessary to complete the following syntheses.
(c) 
Verified step by step guidance1
Analyze the starting material: The molecule contains two terminal alkynes and an acetal protecting group. The acetal is stable under basic conditions but can be hydrolyzed under acidic conditions.
Examine the product: The final molecule has two aldehyde groups, indicating that the terminal alkynes have undergone oxidative cleavage to form aldehydes. Additionally, the acetal group has been hydrolyzed to reveal the aldehyde functionality.
Determine the reagent for oxidative cleavage: To convert terminal alkynes into aldehydes, use an oxidative cleavage reagent such as ozone (O₃) followed by a reducing agent like dimethyl sulfide (DMS) or zinc (Zn) with acetic acid.
Address the acetal hydrolysis: To hydrolyze the acetal group into an aldehyde, use an acidic aqueous solution, such as dilute HCl or H₂SO₄ in water.
Combine the steps: First, perform the oxidative cleavage of the alkynes using O₃ and DMS. Then, hydrolyze the acetal group using dilute acid to complete the synthesis.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Alkyne Hydration
Alkyne hydration is a chemical reaction where an alkyne reacts with water in the presence of an acid or a catalyst to form an alcohol. This process typically involves the addition of water across the triple bond of the alkyne, resulting in the formation of a carbonyl compound or an enol, which can further tautomerize to a ketone or aldehyde. Understanding this reaction is crucial for predicting the necessary reagents for the synthesis shown.
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09:11
Alkyne Hydration
Reagents for Hydration
The common reagents used for alkyne hydration include water (H2O), a strong acid like sulfuric acid (H2SO4), and sometimes mercuric sulfate (HgSO4) as a catalyst. These reagents facilitate the addition of water to the alkyne, leading to the formation of the desired product. Recognizing the role of these reagents is essential for completing the synthesis reaction depicted in the question.
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Tautomerization
Tautomerization is a chemical process where a compound can exist in two interconvertible forms, typically involving the migration of a hydrogen atom and a switch of a double bond. In the context of alkyne hydration, the initial product (enol) can tautomerize to form a more stable ketone or aldehyde. This concept is important for understanding the final product of the synthesis and the stability of the resulting compounds.
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Related Practice
Textbook Question
Identify the bonds broken and formed in the following addition reaction.
(a) Would you expect this reaction to be favored based on entropy?
(b) Based on enthalpy [qualitatively]?
(c) Overall?
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Textbook Question
Another way the preceding might be presented is to say that the minor resonance structure(s) reveal the reactivity of a molecule. Show how the minor resonance structure(s) can help us understand that the following reactions occur with the regioselectivity shown.
(a)
(b)
(c)
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Textbook Question
Predict the product of the following aldehyde/ketone syntheses.
(d)
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Textbook Question
Predict the reagents or reactant(s) necessary to complete the following syntheses.
(a)
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Textbook Question
Classify the following nucleophiles as strong, weak, or intermediate. Would you expect each to add to a carbonyl directly or wait for a carbocation to form?
(a)
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