Textbook Question
Draw a mechanism for the acidic hydrolysis of the magnesium salt shown below to acetophenone.
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Ch. 21 - Carboxylic Acid Derivatives
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 21, Problem 24b
Propose a mechanism for the reduction of octanoyl chloride by lithium aluminum hydride.
Verified step by step guidance1
Step 1: Recognize the functional groups involved. Octanoyl chloride is an acyl chloride, which is a reactive carboxylic acid derivative. Lithium aluminum hydride (LiAlH₄) is a strong reducing agent commonly used to reduce acyl chlorides to primary alcohols.
Step 2: Initiate the mechanism by identifying the nucleophilic attack. The hydride ion (H⁻) from LiAlH₄ acts as a nucleophile and attacks the carbonyl carbon of the octanoyl chloride. This forms a tetrahedral intermediate. Represent this step using the chemical equation:
Step 3: Describe the collapse of the tetrahedral intermediate. The intermediate collapses, expelling the chloride ion (Cl⁻) as a leaving group. This results in the formation of an aldehyde intermediate. Represent this step using the chemical equation:
Step 4: Explain the second reduction step. Another hydride ion (H⁻) from LiAlH₄ attacks the aldehyde intermediate, forming a second tetrahedral intermediate. This intermediate eventually collapses to yield the primary alcohol. Represent this step using the chemical equation:
Step 5: Summarize the overall reaction. The reduction of octanoyl chloride by LiAlH₄ proceeds through two key steps: (1) reduction to an aldehyde intermediate, and (2) further reduction to a primary alcohol. The final product is octanol, a primary alcohol. Ensure to balance the reaction and account for all byproducts such as Cl⁻.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reduction Reactions
Reduction reactions involve the gain of electrons or the decrease in oxidation state by a molecule. In organic chemistry, this often refers to the conversion of carbonyl compounds, like acyl chlorides, into alcohols. Understanding the principles of reduction is essential for proposing mechanisms, as it dictates how reactants interact and transform.
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Reductive Amination
Lithium Aluminum Hydride (LiAlH4)
Lithium aluminum hydride is a powerful reducing agent commonly used in organic synthesis. It can donate hydride ions (H-) to electrophilic centers, such as carbonyl groups, facilitating their reduction. Recognizing its reactivity and mechanism of action is crucial for understanding how it reduces octanoyl chloride to octanol.
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Mechanism of Nucleophilic Acyl Substitution
The mechanism of nucleophilic acyl substitution describes how nucleophiles attack acyl compounds, leading to the replacement of a leaving group. In the case of octanoyl chloride, the hydride from LiAlH4 acts as a nucleophile, attacking the carbonyl carbon and forming an alkoxide intermediate. This concept is vital for detailing the stepwise process of the reduction.
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01:47Nucleophiles and Electrophiles can react in Substitution Reactions.
Related Practice
Textbook Question
Draw a mechanism for the reaction of propanoyl chloride with 2 moles of phenylmagnesium bromide.
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Textbook Question
In which step(s) of the hydride reduction of an ester does the compound undergo reduction? (Hint: Count the bonds to oxygen.)
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Textbook Question
The mechanism for acidic hydrolysis of a nitrile resembles the basic hydrolysis, except that the nitrile is first protonated, activating it toward attack by a weak nucleophile (water). Under acidic conditions, the proton transfer (tautomerism) involves protonation on nitrogen followed by deprotonation on oxygen. Propose a mechanism for the acid-catalyzed hydrolysis of benzonitrile to benzamide.
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Textbook Question
Propose a mechanism for the basic hydrolysis of benzonitrile to the benzoate ion and ammonia.
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Textbook Question
Show how you would add a Grignard reagent to an ester or a nitrile to synthesize
(a) 4-phenylheptan-4-ol.
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