Textbook Question
Which is more highly regioselective: reaction of an alkene with BH3 or with 9-BBN?
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Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions
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. 6 - The Reactions of Alkenes • The Stereochemistry of Addition ReactionsProblem 19a
Bruice 8th EditionCh. 6 - The Reactions of Alkenes • The Stereochemistry of Addition ReactionsProblem 19aChapter 7, Problem 19a
What is the major product obtained from hydroboration–oxidation of the following alkenes?
a. 2-methyl-2-butene
Verified step by step guidance1
Identify the alkene structure in the given image. Hydroboration-oxidation is a two-step reaction that converts alkenes into alcohols.
Understand the mechanism: In the first step, hydroboration, the alkene reacts with borane (BH3) to form a trialkylborane intermediate. This step is syn-addition, meaning both the boron and hydrogen add to the same side of the alkene.
Consider regioselectivity: Hydroboration-oxidation follows anti-Markovnikov addition, where the boron atom attaches to the less substituted carbon of the alkene, leading to the formation of the more stable carbocation.
Proceed to the oxidation step: The trialkylborane intermediate is oxidized using hydrogen peroxide (H2O2) in the presence of a base (usually NaOH), replacing the boron with a hydroxyl group (-OH).
Determine the major product: The final product is an alcohol where the -OH group is attached to the less substituted carbon of the original alkene, following the anti-Markovnikov rule.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydroboration-Oxidation
Hydroboration-oxidation is a two-step reaction process used to convert alkenes into alcohols. In the first step, hydroboration involves the addition of borane (BH3) to the alkene, resulting in the formation of an organoborane intermediate. The second step, oxidation, typically involves the treatment of the organoborane with hydrogen peroxide (H2O2) in a basic solution, leading to the formation of an alcohol. This reaction is notable for its anti-Markovnikov selectivity.
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06:38
General properties of hydroboration-oxidation.
Anti-Markovnikov Addition
Anti-Markovnikov addition refers to the regioselectivity observed in certain reactions, where the less substituted carbon of an alkene receives the new substituent. In the context of hydroboration-oxidation, this means that the hydroxyl group (–OH) ends up on the less substituted carbon of the alkene, while the boron atom attaches to the more substituted carbon. This contrasts with Markovnikov's rule, which predicts that the more substituted carbon would typically receive the electrophile.
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02:43Anti-Markovnikov addition of alcohols to terminal alkynes yields aldehydes
Regioselectivity
Regioselectivity is a term used to describe the preference of a chemical reaction to yield one structural isomer over others when multiple products are possible. In hydroboration-oxidation, regioselectivity is crucial as it determines the position of the hydroxyl group in the final alcohol product. Understanding regioselectivity helps predict the major product formed from the reaction of specific alkenes, which is essential for synthetic organic chemistry.
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Related Practice
Textbook Question
How does the first step in the reaction of propene with Br2 differ from the first step in the reaction of propene with HBr?
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Textbook Question
What is the major product obtained from the reaction of HBr with each of the following?
a.
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Textbook Question
What is the major product obtained from the reaction of HBr with each of the following?
b.
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Textbook Question
To understand why Br− adds to a carbon of the bromonium ion rather than to the positively charged bromine, draw the product that would be obtained if Br− did add to bromine.
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Textbook Question
What will be the product of the preceding reaction if HBr is used in place of Br2?
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