Textbook Question
The following reaction takes place several times faster than the reaction of 2-chlorobutane with HO-:
b. Explain why the OH group in the product is not bonded to the carbon that was bonded to the Cl group in the reactant.
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Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds
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. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing CompoundsProblem 91c
Bruice 8th EditionCh. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing CompoundsProblem 91cChapter 11, Problem 91c
Propose a mechanism for each of the following reactions:
c. 
Verified step by step guidance1
Step 1: Protonation of the alcohol group - The reaction begins with the protonation of the hydroxyl (-OH) group by sulfuric acid (H₂SO₄). This converts the alcohol into a better leaving group, forming a positively charged oxonium ion.
Step 2: Formation of a carbocation - The oxonium ion undergoes loss of water (H₂O), resulting in the formation of a carbocation at the carbon where the hydroxyl group was originally attached. This carbocation is stabilized by resonance with the adjacent double bond.
Step 3: Rearrangement of the carbocation - A hydride shift or alkyl shift occurs to form a more stable carbocation. In this case, the rearrangement leads to a tertiary carbocation, which is more stable due to hyperconjugation and inductive effects.
Step 4: Cyclization - The newly formed carbocation undergoes an intramolecular electrophilic attack by the double bond in the molecule, leading to the formation of a new ring structure. This step forms the fused bicyclic system observed in the product.
Step 5: Deprotonation - Finally, a proton is removed from the positively charged intermediate by water or another base present in the reaction mixture, restoring the double bond and completing the formation of the aromatic bicyclic product.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acid-Catalyzed Dehydration
Acid-catalyzed dehydration is a reaction where an alcohol is converted into an alkene through the removal of a water molecule, facilitated by an acid such as sulfuric acid (H2SO4). The acid protonates the hydroxyl group, making it a better leaving group, which then departs as water, leading to the formation of a carbocation that can rearrange or lose a proton to form a double bond.
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General features of acid-catalyzed dehydration.
Carbocation Stability
Carbocation stability is crucial in organic reactions, as more stable carbocations are formed preferentially. Stability is influenced by factors such as the degree of substitution (tertiary > secondary > primary) and resonance. In the mechanism of dehydration, the formation of a more stable carbocation intermediate can lead to a more favorable reaction pathway and product distribution.
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Rearrangement of Intermediates
Rearrangement of intermediates refers to the process where carbocations can shift their structure to form more stable configurations during a reaction. This can involve hydride or alkyl shifts, which can lead to the formation of different products. Understanding this concept is essential for predicting the outcome of reactions involving carbocations, such as in the dehydration of alcohols.
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Related Practice
Textbook Question
Propose a mechanism for each of the following reactions:
b.
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Textbook Question
A vicinal diol has OH groups on adjacent carbons. The dehydration of a vicinal diol is accompanied by a rearrangement called the pinacol rearrangement. Propose a mechanism for this reaction.
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Textbook Question
Although 2-methyl-1,2-propanediol is an unsymmetrical vicinal diol, only one product is obtained when it is dehydrated in an acidic solution.
b. Why is only one product obtained?
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Textbook Question
Although 2-methyl-1,2-propanediol is an unsymmetrical vicinal diol, only one product is obtained when it is dehydrated in an acidic solution.
a. What is this product?
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Textbook Question
Which of the following reactions occurs more rapidly?
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