Textbook Question
Predict the major products of the following reactions.
(c) 2-methylpent-2-ene + BH3⋅THF
(d) the product from part (c) + H2O2/OH−
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Ch.8 - Reactions of Alkenes
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 8, Problem 11a
Show how you would accomplish the following synthetic conversions.
a. but-1-ene → butan-1-ol
Verified step by step guidance1
Step 1: Begin by identifying the functional group transformation. In this case, you are converting an alkene (but-1-ene) into an alcohol (butan-1-ol). This typically involves an electrophilic addition reaction where water is added across the double bond.
Step 2: Use hydroboration-oxidation as the method for this transformation. Hydroboration-oxidation is a two-step reaction that converts alkenes into alcohols with anti-Markovnikov regioselectivity, ensuring the hydroxyl group (-OH) is added to the terminal carbon.
Step 3: In the first step of hydroboration, react but-1-ene with diborane (B₂H₆) or a borane reagent such as BH₃·THF (borane-tetrahydrofuran complex). This step forms an organoborane intermediate where boron attaches to the less substituted carbon of the double bond.
Step 4: In the second step, oxidize the organoborane intermediate using hydrogen peroxide (H₂O₂) in the presence of a base such as sodium hydroxide (NaOH). This oxidation replaces the boron atom with a hydroxyl group (-OH), yielding butan-1-ol.
Step 5: Verify the product structure to ensure the hydroxyl group is attached to the terminal carbon, confirming the anti-Markovnikov addition. The reaction sequence is complete, and the synthetic conversion is accomplished.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electrophilic Addition
Electrophilic addition is a fundamental reaction mechanism in organic chemistry where an electrophile reacts with a nucleophile, typically involving alkenes. In the case of converting but-1-ene to butan-1-ol, the alkene undergoes electrophilic addition with water in the presence of an acid catalyst, leading to the formation of an alcohol. Understanding this mechanism is crucial for predicting the products of reactions involving alkenes.
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1,2 vs 1,4 Addition
Markovnikov's Rule
Markovnikov's Rule states that in the addition of HX to an alkene, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This principle helps predict the regioselectivity of the reaction when converting but-1-ene to butan-1-ol, ensuring that the hydroxyl group ends up on the more substituted carbon, resulting in the correct alcohol product.
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Acid-Catalyzed Hydration
Acid-catalyzed hydration is a reaction where water adds to an alkene in the presence of an acid, facilitating the conversion of alkenes to alcohols. This process involves the formation of a carbocation intermediate, which can rearrange or react with water to form the alcohol. Recognizing this mechanism is essential for understanding how but-1-ene can be transformed into butan-1-ol through hydration.
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Related Practice
Textbook Question
Predict the major products of the following reactions.
a. propene + BH3⋅THF
b. the product from part (a) + H2O2/OH−
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Textbook Question
Show how you would accomplish the following synthetic conversions.
c. 2-bromo-2,4-dimethylpentane → 2,4-dimethylpentan-3-ol
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Textbook Question
Show how you would accomplish the following synthetic conversions.
(b) but-1-ene → butan-2-ol
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Textbook Question
In the hydroboration of 1-methylcyclopentene shown in Solved Problem 8-3, the reagents are achiral, and the products are chiral. The product is a racemic mixture of trans-2-methylcyclopentanol, but only one enantiomer is shown. Show how the other enantiomer is formed.
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Textbook Question
Show how you would accomplish the following synthetic conversions.
c. 3-methylpent-1-ene → 3-methylpentan-2-ol
Explain why acid-catalyzed hydration would be a poor choice for the reaction in (c).
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