Textbook Question
In the following allylic radicals, identify the carbon where the new C― Br bond is most likely to form in the second propagation step.
(c)
1
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Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical 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. 11 - Properties and Synthesis of Alkyl Halides: Radical ReactionsProblem 31b
Mullins 1st EditionCh. 11 - Properties and Synthesis of Alkyl Halides: Radical ReactionsProblem 31bChapter 10, Problem 31b
In the following allylic radicals, identify the carbon where the new C― Br bond is most likely to form in the second propagation step.
(b) 
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Identify the structure of the allylic radical. An allylic radical is a radical located at the carbon atom adjacent to a double bond. This radical is stabilized by resonance.
Draw the resonance structures of the allylic radical. Resonance structures are different ways of arranging the electrons in a molecule that can help visualize the distribution of electron density.
Examine the resonance structures to determine which carbon atoms have the highest electron density. The carbon with the highest electron density is the most likely site for the formation of a new bond.
Consider the stability of the potential new C―Br bond. The bond is more likely to form at the carbon that results in the most stable product, often the one with the most substituted carbon.
Select the carbon atom where the new C―Br bond is most likely to form based on the resonance structures and stability considerations. This is typically the carbon that is most substituted or has the highest electron density in the resonance structures.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Allylic Radical Stability
Allylic radicals are stabilized by resonance, which allows the unpaired electron to be delocalized over multiple atoms. This delocalization increases the stability of the radical, making allylic positions more reactive in radical reactions. Understanding this stability is crucial for predicting where new bonds will form.
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The radical stability trend.
Resonance Structures
Resonance structures are different ways of drawing the same molecule, showing the delocalization of electrons. In allylic radicals, resonance allows the radical to be spread over several carbon atoms, influencing the site of reactivity. Identifying resonance structures helps determine the most stable and reactive positions for bond formation.
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03:04Drawing Resonance Structures
Radical Propagation Steps
Radical reactions proceed through initiation, propagation, and termination steps. In the propagation step, radicals react with other molecules to form new radicals and products. Understanding the mechanism of propagation, especially in allylic systems, is essential for predicting where new bonds, such as C-Br, will form.
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Related Practice
Textbook Question
In the following molecules, identify the carbon where the radical is most likely to form in the first propagation step.
(c)
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Textbook Question
Predict the products of the following allylic halogenation reactions.
(c)
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Textbook Question
In the following molecules, identify the carbon where the radical is most likely to form in the first propagation step.
(d)
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Textbook Question
Predict the products of the following allylic halogenation reactions.
(a)
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Textbook Question
In the following allylic radicals, identify the carbon where the new C–Br bond is most likely to form in the second propagation step.
(a)
2
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