Textbook Question
Provide a mechanism for the formation of the hemiacetals shown. [Only (c) is favored as written.]
(a)
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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 26a
Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 26aChapter 16, Problem 26a
Suggest the appropriate carbonyl and Wittig reagent to make the following alkenes.
a. (E)-7-methylnon-4-en-3-one
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Step 1: Understand the Wittig reaction, which involves the reaction of a phosphonium ylide with a carbonyl compound to form an alkene. The ylide is typically formed from a triphenylphosphine and an alkyl halide.
Step 2: Identify the target alkene structure, (E)-7-methylnon-4-en-3-one. Note the position of the double bond and the stereochemistry (E configuration).
Step 3: Determine the carbonyl compound needed. The Wittig reaction forms the double bond at the site of the carbonyl group. For (E)-7-methylnon-4-en-3-one, the carbonyl group should be at the 3-position, suggesting the use of 3-oxononanal as the carbonyl compound.
Step 4: Identify the Wittig reagent. The Wittig reagent should provide the remaining carbon chain that forms the alkene. For (E)-7-methylnon-4-en-3-one, the Wittig reagent should be a phosphonium ylide derived from 4-methylbutyltriphenylphosphonium bromide.
Step 5: Consider the stereochemistry. The (E) configuration indicates that the Wittig reaction should be controlled to favor the trans product. This can be influenced by the choice of base and reaction conditions.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Wittig Reaction
The Wittig reaction is a chemical reaction used to convert carbonyl compounds, such as aldehydes and ketones, into alkenes. This transformation involves the reaction of a phosphonium ylide with a carbonyl compound, resulting in the formation of a new carbon-carbon double bond. Understanding the mechanism and the stereochemistry of the Wittig reaction is crucial for predicting the structure of the resulting alkene.
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Carbonyl Compounds
Carbonyl compounds are organic molecules that contain a carbon-oxygen double bond. They are key intermediates in many organic reactions, including the Wittig reaction. In the context of synthesizing alkenes, selecting the appropriate carbonyl compound is essential, as it determines the position and configuration of the double bond in the final alkene product.
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Stereochemistry of Alkenes
Stereochemistry refers to the spatial arrangement of atoms in molecules and its impact on the physical and chemical properties of compounds. In alkenes, stereochemistry is particularly important because it affects the E/Z configuration of the double bond. For the synthesis of (E)-7-methylnon-4-en-3-one, understanding how to control and predict the stereochemistry during the Wittig reaction is crucial for obtaining the desired (E)-isomer.
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Related Practice
Textbook Question
Suggest an acetylide ion and a carbonyl that might be used to make the following products.
(c) 5-phenylhex-2-yn-1-ol
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Textbook Question
Suggest a carbonyl to react with NaCN/HCN to produce the following cyanohydrins.
(a)
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Textbook Question
Identify the hemiacetal functional group in each of the following molecules. These molecules may not be stable enough to be the favorable product in an equilibrium reaction.
(c)
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Textbook Question
Which of the following cyclic hemiacetals would you expect to have the highest Keq for their formation? Explain your answer.
(a)
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Textbook Question
For each of the following carbonyl addition reactions, would you expect a racemic mixture or a mixture enriched in one stereoisomer? In each case, draw both possible stereoisomeric products.
(a)
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