Textbook Question
For each of the following alkynes, draw the products obtained from (1) the acid-catalyzed addition of water (mercuric ion is added for part a) and from (2) hydroboration–oxidation:
a. 1-butyne
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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 19b
Bruice 8th EditionCh. 7 - The Reactions of Alkynes • An Introduction to Multistep SynthesisProblem 19bChapter 8, Problem 19b
Describe the alkyne you should start with and the reagents you should use if you want to synthesize
b. cis-2-butene.
Verified step by step guidance1
Step 1: Recognize that cis-2-butene is an alkene with a cis configuration, meaning the two substituents on the double bond are on the same side. To synthesize this, you need to start with an alkyne and perform a partial reduction.
Step 2: Identify the alkyne that can lead to cis-2-butene. The alkyne should have the same carbon skeleton as the desired product. In this case, the starting alkyne is 2-butyne (CH≡C-CH₂-CH₃).
Step 3: Choose the appropriate reagents for partial reduction to achieve the cis configuration. Use Lindlar's catalyst, which is a palladium catalyst poisoned with lead or quinoline, to selectively reduce the alkyne to a cis alkene.
Step 4: Understand the mechanism of the reaction. Lindlar's catalyst facilitates the addition of hydrogen (H₂) to the triple bond in a syn fashion, meaning both hydrogens add to the same side of the molecule, resulting in the cis configuration.
Step 5: Ensure the reaction conditions are mild and avoid over-reduction. Using Lindlar's catalyst prevents the alkyne from being fully reduced to an alkane, stopping at the alkene stage.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Alkynes
Alkynes are hydrocarbons that contain at least one carbon-carbon triple bond. They are unsaturated compounds and can participate in various chemical reactions, including addition reactions. Understanding the structure and reactivity of alkynes is crucial for determining the appropriate starting material for synthesizing other compounds, such as alkenes.
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09:11
Alkyne Hydration
Hydroboration-Oxidation
Hydroboration-oxidation is a two-step reaction process used to convert alkynes into alkenes with specific stereochemistry. In the first step, an alkyl borane is formed, which adds across the triple bond. The subsequent oxidation step replaces the boron with a hydroxyl group, leading to the formation of an alcohol that can be dehydrated to yield the desired alkene, such as cis-2-butene.
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06:38General properties of hydroboration-oxidation.
Stereochemistry
Stereochemistry refers to the spatial arrangement of atoms in molecules and how this affects their chemical properties and reactions. In the case of cis-2-butene, the specific arrangement of substituents around the double bond is crucial for its identification. Understanding stereochemistry is essential for predicting the outcome of reactions and ensuring the correct isomer is synthesized.
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1:38Polymer Stereochemistry Concept 1
Related Practice
Textbook Question
Only one alkyne forms an aldehyde when it undergoes the mercuric-ion-catalyzed addition of water. Identify the alkyne.
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Textbook Question
Describe the alkyne you should start with and the reagents you should use if you want to synthesize
a. pentane.
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Textbook Question
What are products of the following reactions?
b.
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Textbook Question
What are products of the following reactions?
a.
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Textbook Question
Describe the alkyne you should start with and the reagents you should use if you want to synthesize
c. trans-2-pentene.
d. 1-hexene.
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