Textbook Question
Two stereoisomers are obtained from the reaction of cyclopentene oxide and dimethylamine. The R,R-isomer is used in the manufacture of eclanamine, an antidepressant. What other isomer is obtained?
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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 93a
Bruice 8th EditionCh. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing CompoundsProblem 93aChapter 11, Problem 93a
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?
Verified step by step guidance1
Step 1: Begin by identifying the structure of 2-methyl-1,2-propanediol. It is a vicinal diol, meaning the hydroxyl (-OH) groups are on adjacent carbon atoms. The molecule has a methyl group attached to the second carbon.
Step 2: Understand the dehydration reaction mechanism in acidic conditions. Dehydration involves the removal of water (H₂O) from the molecule, typically facilitated by an acid catalyst like H₂SO₄ or H₃PO₄.
Step 3: Analyze the protonation step. In acidic conditions, one of the hydroxyl groups is protonated, forming a good leaving group (water). This step is crucial for initiating the reaction.
Step 4: Consider the carbocation intermediate formed after the departure of water. The stability of the carbocation is key to determining the product. In this case, the molecule forms a tertiary carbocation (most stable) due to the methyl group on the second carbon.
Step 5: Examine the final step, where a double bond is formed through elimination of a proton from an adjacent carbon atom. This results in the formation of an alkene. The product is 2-methylpropene, as it is the most stable alkene formed under these conditions.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Vicinal Diols
Vicinal diols, also known as glycols, are organic compounds that contain two hydroxyl (-OH) groups attached to adjacent carbon atoms. In the case of 2-methyl-1,2-propanediol, the presence of these two -OH groups allows for potential dehydration reactions, where water is eliminated to form alkenes. Understanding the structure and reactivity of vicinal diols is crucial for predicting the products of their dehydration.
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General properties of syn vicinal dihydroxylation.
Dehydration Reaction
A dehydration reaction involves the removal of water from a compound, often resulting in the formation of a double bond. In acidic conditions, the hydroxyl groups of vicinal diols can be protonated, leading to the formation of a more stable carbocation intermediate. This process is essential for understanding how 2-methyl-1,2-propanediol can yield a single product upon dehydration, despite its unsymmetrical nature.
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Carbocation Stability
Carbocation stability is a key factor in determining the outcome of dehydration reactions. Tertiary carbocations are more stable than secondary or primary ones due to hyperconjugation and inductive effects from surrounding alkyl groups. In the case of 2-methyl-1,2-propanediol, the dehydration leads to the formation of a stable tertiary carbocation, which ultimately results in the formation of a single alkene product, illustrating the influence of carbocation stability on reaction pathways.
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Related Practice
Textbook Question
Propose a mechanism for each of the following reactions:
b.
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Textbook Question
What product is obtained when the following vicinal diol is heated in an acidic solution?
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
Propose a mechanism for each of the following reactions:
c.
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