Textbook Question
What stereoisomers are obtained when 2-butyne undergoes each of the following reaction sequences?
c. 1. Cl2/CH2Cl2 2. Br2/CH2Cl2
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Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis
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. 7 - The Reactions of Alkynes • An Introduction to Multistep SynthesisProblem 50b
Bruice 8th EditionCh. 7 - The Reactions of Alkynes • An Introduction to Multistep SynthesisProblem 50bChapter 8, Problem 50b
Show how the following compounds can be synthesized starting with ethyne:
b. trans-3-heptene
Verified step by step guidance1
Step 1: Begin with ethyne (C₂H₂) as the starting material. Ethyne is a simple alkyne with a triple bond between two carbon atoms.
Step 2: Perform a hydroboration-oxidation reaction to convert ethyne into an aldehyde. Use reagents such as disiamylborane (R₂BH) followed by hydrogen peroxide (H₂O₂) and sodium hydroxide (NaOH). This will yield acetaldehyde (CH₃CHO).
Step 3: Perform an aldol condensation reaction. React acetaldehyde with another equivalent of acetaldehyde in the presence of a base (e.g., NaOH) to form crotonaldehyde (CH₃CH=CHCHO), which contains a trans double bond.
Step 4: Extend the carbon chain by performing a Wittig reaction. React crotonaldehyde with a Wittig reagent (e.g., a phosphonium ylide derived from propyl bromide) to form trans-3-heptene. This reaction allows for the selective formation of the trans isomer.
Step 5: Purify the product to isolate trans-3-heptene. Use techniques such as distillation or chromatography to ensure the desired compound is obtained in high purity.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Ethyne as a Building Block
Ethyne, also known as acetylene, is a simple alkyne that serves as a versatile building block in organic synthesis. Its triple bond allows for various reactions, including addition reactions with electrophiles, which can lead to the formation of longer carbon chains. Understanding how to manipulate ethyne is crucial for synthesizing more complex molecules like trans-3-heptene.
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Alkene Synthesis
Alkenes, such as trans-3-heptene, can be synthesized through various methods, including elimination reactions and hydroboration-oxidation. The formation of alkenes from alkynes typically involves partial hydrogenation or elimination of a dihalide. Recognizing the appropriate reaction pathways is essential for constructing the desired alkene from ethyne.
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Stereochemistry of Alkenes
Stereochemistry refers to the spatial arrangement of atoms in molecules and is particularly important in alkenes, which can exhibit geometric isomerism. trans-3-heptene has a specific configuration where substituents are on opposite sides of the double bond. Understanding stereochemistry is vital for ensuring the correct isomer is synthesized, as different isomers can have distinct physical and chemical properties.
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Related Practice
Textbook Question
What stereoisomers are obtained when 2-butyne undergoes each of the following reaction sequences?
a. 1. H2/Lindlar catalyst 2. Br2/CH2Cl2
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Textbook Question
Show how each of the following compounds can be prepared using the given starting material, any needed inorganic reagents, and any organic compound that has no more than four carbons:
b.
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Textbook Question
Show how each of the following compounds can be prepared using the given starting material, any needed inorganic reagents, and any organic compound that has no more than four carbons:
a.
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Textbook Question
Show how the following compounds can be synthesized starting with ethyne:
a. cis-2-octene
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Textbook Question
Show how each of the following compounds can be prepared using the given starting material, any needed inorganic reagents, and any organic compound that has no more than four carbons:
c.
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