Textbook Question
Predict the product(s) when each of the following are reacted with mCPBA, making sure to indicate the relative stereochemical outcome. Indicate any racemic mixtures by drawing both enantiomers.
(d)
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Ch. 9 - Alkenes II: Oxidation and Reduction
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
Chapter 8, Problem 14
How does the carbonyl in mCPBA weaken the O―O σ bond (i.e., make a better leaving group)?
Verified step by step guidance1
The O―O σ bond in peroxides, such as hydrogen peroxide (HO―OH), is inherently weak due to the repulsion between the lone pairs on the adjacent oxygen atoms. This bond can be further weakened by electronic effects from substituents.
In mCPBA (meta-chloroperoxybenzoic acid), the carbonyl group (C=O) is highly electronegative and withdraws electron density from the adjacent oxygen atoms through resonance and inductive effects.
The electron-withdrawing nature of the carbonyl group stabilizes the negative charge on the leaving group (the oxygen atom) when the O―O bond breaks, making the bond easier to cleave.
Additionally, the resonance structure of mCPBA allows delocalization of electrons from the carbonyl group, further reducing electron density on the O―O bond and weakening it.
The presence of the aromatic ring and the chlorine substituent in mCPBA also contributes to the electron-withdrawing effects, enhancing the ability of the O―O bond to act as a better leaving group compared to hydrogen peroxide.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Carbonyl Group Reactivity
The carbonyl group (C=O) is highly polar, with a partial positive charge on the carbon atom and a partial negative charge on the oxygen. This polarity makes the carbonyl carbon susceptible to nucleophilic attack, which can lead to the formation of more reactive intermediates. In the context of mCPBA, the carbonyl's reactivity plays a crucial role in facilitating the weakening of the O―O bond.
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Peroxide Bond Strength
The O―O bond in peroxides, such as mCPBA, is relatively weak compared to other covalent bonds. This weakness is due to the repulsion between the lone pairs of electrons on the oxygen atoms. When the carbonyl group interacts with the peroxide, it can stabilize the transition state, leading to a decrease in the O―O bond strength and making it a better leaving group during reactions.
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Leaving Group Ability
A leaving group is an atom or group that can depart from the parent molecule during a chemical reaction, often taking with it a pair of electrons. The ability of a leaving group to depart is influenced by its stability after leaving. In the case of mCPBA, the weakening of the O―O bond enhances the leaving group's ability, as the resulting species can be more stable, thus facilitating the overall reaction.
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Related Practice
Textbook Question
Suggest an alkene that could be used to make each of the following halohydrins.
(a)
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Textbook Question
Suggest an alkene that could be used to make each of the following halohydrins.
(c)
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Textbook Question
Calculate the atom economy of the reaction in Figure 9.24. [Catalysts are not included in the atom economy calculation.]
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Textbook Question
Predict the product(s) when each of the following are reacted with mCPBA, making sure to indicate the relative stereochemical outcome. Indicate any racemic mixtures by drawing both enantiomers.
(a)
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Textbook Question
Explain why water attacks the carbon of the bromonium ion as opposed to the bromonium ion itself in the second step of halohydrin formation.
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