Domanda del libro di testo
Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.
(d)
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Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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TOC.tableOfContents
- 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 1: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes 2: 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 1: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification 2: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution 1: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution 2: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems 1: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems 2: Pericyclic Reactions54
- Ch. 23 - Benzene 1: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene 2: 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: 9780137566471Non è quello che usi tu?Cambia libro di testo
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Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblema 79
Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblema 79Capitolo 16, Problema 79
We show in Chapter 20 that α , β-unsaturated ketones are electrophilic at C4. Rationalize this observation.
Guida verificata passo dopo passo1
Understand the structure of α, β-unsaturated ketones: These compounds contain a conjugated system where a carbonyl group (C=O) is directly connected to a double bond (C=C). This conjugation allows for delocalization of electrons across the π-system, which is key to their reactivity.
Analyze the electrophilicity of the β-carbon (C₄): The conjugated system creates resonance structures. One important resonance structure shows the movement of electrons from the double bond toward the oxygen atom of the carbonyl group, resulting in a partial positive charge on the β-carbon (C₄). This makes C₄ electrophilic and susceptible to nucleophilic attack.
Write the resonance structures: To rationalize the observation, draw the resonance structures of the α, β-unsaturated ketone. Show how the electrons from the π-bond of the C=C double bond shift toward the carbonyl oxygen, creating a positive charge on C₄. Use MathML to represent the resonance structures clearly.
Consider the role of the carbonyl group: The carbonyl oxygen is highly electronegative and pulls electron density away from the conjugated system. This effect further enhances the partial positive charge on C₄, increasing its electrophilicity.
Relate this to reactivity: The electrophilic nature of C₄ explains why α, β-unsaturated ketones are reactive at this position. Nucleophiles are attracted to the positively charged C₄, leading to addition reactions at this site. This concept will be explored in more detail in Chapter 20.
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Electrophilicity
Electrophilicity refers to the tendency of a species to accept electrons. In organic chemistry, electrophiles are typically electron-deficient species that can react with nucleophiles, which are electron-rich. Understanding the factors that influence electrophilicity, such as the presence of electron-withdrawing groups, is crucial for rationalizing the reactivity of compounds like α, β-unsaturated ketones.
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03:
Nucleophile or Electrophile
α, β-Unsaturated Ketones
α, β-Unsaturated ketones are compounds that contain a carbonyl group (C=O) adjacent to a double bond (C=C). This structural feature creates a conjugated system that stabilizes the molecule and enhances its electrophilic character at the β-carbon. The resonance between the carbonyl and the double bond plays a significant role in determining the reactivity of these compounds.
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02:39The difference between saturated and unsaturated molecules.
Resonance Stabilization
Resonance stabilization occurs when a molecule can be represented by multiple valid Lewis structures, leading to a delocalization of electrons. In α, β-unsaturated ketones, the resonance between the carbonyl and the adjacent double bond increases the positive character at the β-carbon, making it more electrophilic. This concept is essential for understanding why these compounds are reactive towards nucleophiles.
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03:43The radical stability trend.
Pratica correlata
Domanda del libro di testo
When a ketone is dissolved in 18O-labeled water, the 18O label is incorporated into the ketone. Suggest a mechanism that explains this observation.
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Domanda del libro di testo
As discussed in Section 17.9.1, alkenes can be hydrogenated selectively in the presence of ketones. Suppose that was not the case, and suggest how you might use a protecting group strategy to generate A from B.
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