Textbook Question
What alcohol would you treat with phosphorus oxychloride and pyridine to form each of the following alkenes?
a.
b.
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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 19a
Bruice 8th EditionCh. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing CompoundsProblem 19aChapter 11, Problem 19a
What stereoisomers are formed in the following reactions? Which stereoisomer is the major product?
a. the acid-catalyzed dehydration of 1-pentanol to 2-pentene
Verified step by step guidance1
Step 1: Understand the reaction mechanism. The acid-catalyzed dehydration of 1-pentanol involves the removal of a water molecule to form an alkene. This reaction proceeds via an E1 mechanism, which includes the formation of a carbocation intermediate.
Step 2: Identify the carbocation intermediate. Protonation of the hydroxyl group (-OH) in 1-pentanol converts it into a better leaving group (water). The departure of water generates a carbocation at the 1-position. This carbocation can undergo a hydride shift to form a more stable secondary carbocation at the 2-position.
Step 3: Determine the possible alkenes. The secondary carbocation at the 2-position can lose a proton from either the adjacent carbon atoms (C-1 or C-3) to form two possible stereoisomers of 2-pentene: (E)-2-pentene and (Z)-2-pentene.
Step 4: Analyze the stereoisomers. The (E)-2-pentene has the two largest substituents on opposite sides of the double bond, while the (Z)-2-pentene has the two largest substituents on the same side of the double bond. These are geometric isomers (stereoisomers) of 2-pentene.
Step 5: Predict the major product. According to Zaitsev's rule, the more substituted alkene is favored. Additionally, the (E)-isomer is typically more stable than the (Z)-isomer due to reduced steric hindrance. Therefore, (E)-2-pentene is expected to be the major product.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Stereoisomerism
Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. This can lead to different physical and chemical properties. The two main types of stereoisomers are enantiomers, which are non-superimposable mirror images, and diastereomers, which are not mirror images of each other.
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E/Z Nomenclature
E/Z nomenclature is a system used to describe the stereochemistry of alkenes based on the priority of substituents attached to the double bond. The 'E' (entgegen) configuration indicates that the highest priority groups are on opposite sides, while the 'Z' (zusammen) configuration indicates they are on the same side. This nomenclature is crucial for identifying and distinguishing between different stereoisomers formed during reactions.
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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 catalyst. In the case of 1-pentanol, the reaction involves protonation of the alcohol, followed by the loss of water and formation of a carbocation, which can lead to the formation of different stereoisomers depending on the stability of the carbocation and the pathway taken during elimination.
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Related Practice
Textbook Question
Propose a mechanism for each of the following reactions:
a.
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Textbook Question
Explain why the following alcohols, when heated with acid, form the same alkene.
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Textbook Question
Heating an alcohol with sulfuric acid is a good way to prepare a symmetrical ether such as diethyl ether.
b. How would you synthesize ethyl propyl ether?
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Textbook Question
What stereoisomers are formed in the following reactions? Which stereoisomer is the major product?
b. the acid-catalyzed dehydration of 3,4-dimethyl-3-hexanol to 3,4-dimethyl-3-hexene
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Textbook Question
If the compound shown in the margin is heated in the presence of H2SO4,
a. what constitutional isomer would be formed in greatest yield?
b. what stereoisomer would be formed in greater yield?
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