Textbook Question
Draw the structures of the products obtained from the following reaction:
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Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 9 - Substitution and Elimination Reactions of Alkyl HalidesProblem 119a
Bruice 8th EditionCh. 9 - Substitution and Elimination Reactions of Alkyl HalidesProblem 119aChapter 10, Problem 119a
cis-4-Bromocyclohexanol and trans-4-bromocyclohexanol form the same elimination product but a different substitution product when they react with HO−.
a. Why do they form the same elimination product?
Verified step by step guidance1
Step 1: Analyze the elimination reaction mechanism. Elimination reactions typically proceed via an E2 mechanism when a strong base like HO⁻ is present. In an E2 reaction, the base abstracts a proton from a β-carbon, and the leaving group departs simultaneously, forming a double bond.
Step 2: Consider the stereochemistry of the cis- and trans-4-bromocyclohexanol. In both cases, the β-hydrogen and the leaving group (Br) must be anti-periplanar (i.e., opposite and in the same plane) for the elimination to occur.
Step 3: Examine the chair conformations of cis- and trans-4-bromocyclohexanol. In the chair conformation, the anti-periplanar geometry is achievable for both cis and trans isomers because the β-hydrogen and bromine can adopt axial and equatorial positions, respectively, depending on the conformation.
Step 4: Recognize that the elimination product is the same for both isomers because the double bond forms between the same two carbons regardless of the initial stereochemistry of the reactant. The stereochemistry of the starting material does not affect the position of the double bond.
Step 5: Conclude that the same elimination product is formed because the anti-periplanar requirement is satisfied in both cases, and the reaction mechanism leads to the same alkene structure.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Elimination Reactions
Elimination reactions involve the removal of atoms or groups from a molecule, resulting in the formation of a double bond. In the case of cis- and trans-4-bromocyclohexanol, both isomers can undergo elimination to form the same alkene product due to the ability of the hydroxide ion (OH−) to abstract a proton from adjacent carbon atoms, regardless of the stereochemistry of the starting material.
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Recognizing Elimination Reactions.
Stereochemistry
Stereochemistry refers to the spatial arrangement of atoms in molecules and how this affects their chemical behavior. The cis and trans isomers of 4-bromocyclohexanol differ in the orientation of substituents around the cyclohexane ring, which influences their reactivity in substitution reactions but not in elimination reactions, as the formation of the double bond can occur from either configuration.
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Substitution vs. Elimination
Substitution and elimination are two fundamental types of reactions in organic chemistry. While elimination leads to the formation of alkenes, substitution involves replacing one functional group with another. The different products formed by cis- and trans-4-bromocyclohexanol when reacting with OH− highlight how the stereochemistry can influence substitution pathways, leading to distinct products despite similar elimination outcomes.
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Related Practice
Textbook Question
Draw the product of each of the following reactions:
1.
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Textbook Question
How could you prepare the following compounds from the given starting materials?
b.
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Textbook Question
cis-4-Bromocyclohexanol and trans-4-bromocyclohexanol form the same elimination product but a different substitution product when they react with HO−.
b. Explain, by showing the mechanisms, why different substitution products are obtained.
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Textbook Question
Two elimination products are obtained from the following E2 reaction:
a. What are the elimination products?
b. Which is formed in greater yield?
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Textbook Question
cis-4-Bromocyclohexanol and trans-4-bromocyclohexanol form the same elimination product but a different substitution product when they react with HO−.
c. How many stereoisomers does each of the elimination and substitution reactions form?
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