Textbook Question
What product is obtained from the reaction of each of the following alcohols with
a. H2CrO4?
1. 3-pentanol
2. 1-pentanol
3. 2-methyl-2-pentanol
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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 21a,b
Bruice 8th EditionCh. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing CompoundsProblem 21a,bChapter 11, Problem 21a,b
What alcohol would you treat with phosphorus oxychloride and pyridine to form each of the following alkenes?
a. 
b. 
Verified step by step guidance1
Step 1: Recognize that the reaction involves converting an alcohol into an alkene using phosphorus oxychloride (POCl₃) and pyridine. This is an elimination reaction, specifically an E2 mechanism, where the hydroxyl group (-OH) is removed and a double bond is formed.
Step 2: For the first alkene (CH₃CH₂C=CH₂ with a methyl group attached to the second carbon), identify the alcohol precursor. The alcohol must have the hydroxyl group (-OH) attached to the carbon that will lose a hydrogen to form the double bond. The precursor alcohol is CH₃CH₂CH(OH)CH₃.
Step 3: For the second alkene (a cyclohexene with a methyl group attached to the double-bonded carbon), identify the alcohol precursor. The alcohol must have the hydroxyl group (-OH) attached to the carbon adjacent to the double bond. The precursor alcohol is 1-methylcyclohexanol.
Step 4: Understand the role of POCl₃ and pyridine in the reaction. POCl₃ acts as a dehydrating agent, facilitating the removal of the hydroxyl group and a hydrogen atom to form the double bond. Pyridine serves as a base to abstract the proton during the elimination step.
Step 5: Visualize the mechanism. In both cases, the hydroxyl group is converted into a good leaving group by POCl₃, and pyridine abstracts a proton from the β-carbon, leading to the formation of the double bond in the alkene product.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Dehydration of Alcohols
Dehydration of alcohols is a chemical reaction where water is removed from an alcohol to form an alkene. This process can be facilitated by various reagents, including strong acids or reagents like phosphorus oxychloride (POCl3). Understanding the mechanism of dehydration is crucial for predicting the formation of specific alkenes from given alcohols.
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General Reaction of Dehydration with POCl3
Phosphorus Oxychloride (POCl3)
Phosphorus oxychloride is a reagent commonly used in organic synthesis to convert alcohols into alkyl chlorides or to facilitate dehydration reactions. It acts as a dehydrating agent, promoting the elimination of water from alcohols, which is essential for forming alkenes. Its use in conjunction with pyridine helps to neutralize the byproducts and stabilize the reaction environment.
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Regioselectivity in Elimination Reactions
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple products are possible. In elimination reactions involving alcohols, the stability of the resulting alkene (based on factors like substitution and sterics) influences which alkene is formed. Understanding regioselectivity is key to predicting the products of dehydration reactions.
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00:40Recognizing Elimination Reactions.
Related Practice
Textbook Question
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
1553
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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
781
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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?
1557
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Textbook Question
What are the major products obtained when the following ether is heated with one equivalent of HI?
861
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Textbook Question
What product is obtained from the reaction of each of the following alcohols with
c. the regents required for a Swern oxidation?
1. 3-pentanol
2. 1-pentanol
3. 2-methyl-2-pentanol
599
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