Textbook Question
Predict the product of the following reactions.
(j)
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Ch. 21 - Conjugated Systems I: Stability and Addition Reactions
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. 21 - Conjugated Systems I: Stability and Addition ReactionsProblem 58
Mullins 1st EditionCh. 21 - Conjugated Systems I: Stability and Addition ReactionsProblem 58Chapter 20, Problem 58
In Chapter 9, electron-rich alkenes were oxidized under acidic conditions with mCPBA. Conjugated alkenes can be oxidized using the same reagent, but under basic conditions. Suggest a mechanism for this reaction. [Think about what is electron-rich and what is electron-poor in the reaction. Also, identify the bonds formed and broken.]
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Identify the key reactants: The reaction involves a conjugated alkene and mCPBA (meta-chloroperoxybenzoic acid) under basic conditions. mCPBA is an oxidizing agent that typically transfers an oxygen atom to the substrate.
Analyze the electron density: Conjugated alkenes have delocalized π-electrons, making them electron-rich. Under basic conditions, the peroxyacid (mCPBA) deprotonates to form a peroxy anion, which is electron-poor and acts as the electrophile.
Propose the first step of the mechanism: The electron-rich π-system of the conjugated alkene attacks the electrophilic oxygen atom of the peroxy anion. This forms a cyclic intermediate (a three-membered epoxide ring) as the π-bond is broken and a new C-O bond is formed.
Account for bond breaking and formation: During the formation of the epoxide, the O-O bond in the peroxy anion breaks, and the oxygen atom is transferred to the alkene. This step also regenerates the conjugate base of the acid (e.g., m-chlorobenzoate).
Conclude the mechanism: The final product is an epoxide derived from the conjugated alkene. The reaction is stereospecific, so the stereochemistry of the starting alkene will influence the stereochemistry of the epoxide product.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electrophilic Addition Reactions
Electrophilic addition reactions involve the addition of electrophiles to nucleophilic sites in alkenes. In this context, alkenes are electron-rich due to their π bonds, making them susceptible to attack by electrophiles like mCPBA. Understanding this mechanism is crucial for predicting the products formed when alkenes react under different conditions.
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05:39
Features of Addition Mechanisms.
Oxidation Mechanisms
Oxidation mechanisms in organic chemistry often involve the addition of oxygen or the removal of hydrogen. In the case of mCPBA, it acts as a peracid that can introduce an oxygen atom into the alkene, forming an epoxide. Recognizing how oxidation alters the structure and reactivity of the starting material is essential for proposing a detailed reaction mechanism.
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01:31Oxidative Workup Mechanism:
Basic vs. Acidic Conditions
The reaction conditions, whether acidic or basic, significantly influence the mechanism and outcome of the reaction. Acidic conditions can stabilize carbocation intermediates, while basic conditions may favor nucleophilic attack on the epoxide formed. Understanding how these conditions affect electron density and the stability of intermediates is vital for accurately suggesting a reaction mechanism.
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06:21Understanding the difference between basicity and nucleophilicity.
Related Practice
Textbook Question
The following transformation was found to occur in areas with large NO₂ emissions. Suggest a mechanism for the reaction (J. Phys. Chem. 2013, 117, 14132–14140). [Hint: Use the fishhook arrows associated with radical reactions.]
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Textbook Question
Predict the product of the following reactions.
(d)
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Textbook Question
The reactivity of cyclopropanes often mimics that of alkenes.
(a) On the basis of this, suggest a mechanism for the following reaction.
2
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Textbook Question
The reactivity of cyclopropanes often mimics that of alkenes.
(b) Besides opening the three-membered ring, what is the driving force for this reaction?
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Textbook Question
Predict the product of the following reactions.
(i)
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