Textbook Question
Show how Friedel–Crafts acylation might be used to synthesize the following compounds.
c. n-butylbenzene
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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 28c
Show how you would add a Grignard reagent to an ester or a nitrile to synthesize
(c) pentan-2-one.
Verified step by step guidance1
Identify the target molecule, pentan-2-one, which is a ketone. The goal is to synthesize this compound using a Grignard reagent and either an ester or a nitrile as the starting material.
Choose an appropriate Grignard reagent. To form pentan-2-one, the Grignard reagent should add a two-carbon chain to the starting material. Use ethylmagnesium bromide (CH₃CH₂MgBr) as the Grignard reagent.
If starting with an ester, select an ester that will yield the desired ketone after the Grignard reaction. For pentan-2-one, use methyl propanoate (CH₃CH₂COOCH₃) as the ester. The Grignard reagent will add to the carbonyl carbon of the ester.
If starting with a nitrile, select a nitrile that will yield the desired ketone after the Grignard reaction. For pentan-2-one, use propanenitrile (CH₃CH₂CN). The Grignard reagent will add to the carbon of the nitrile group, forming an imine intermediate, which is then hydrolyzed to the ketone.
Perform the reaction: (1) React the Grignard reagent with the ester or nitrile under anhydrous conditions to form the intermediate. (2) For the ester, the intermediate will collapse to form the ketone directly. For the nitrile, hydrolyze the imine intermediate with aqueous acid to yield the ketone, pentan-2-one.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Grignard Reagents
Grignard reagents are organomagnesium compounds represented as R-MgX, where R is an organic group and X is a halogen. They are highly reactive nucleophiles that can add to electrophilic carbonyl groups, such as esters and nitriles, facilitating the formation of new carbon-carbon bonds. Understanding their reactivity is crucial for synthesizing ketones and other carbonyl compounds.
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Carbonation of Grignard Reagents
Ester Reactivity
Esters are organic compounds characterized by the functional group RCOOR', where R and R' are hydrocarbon chains. They can undergo nucleophilic addition reactions with Grignard reagents, leading to the formation of tertiary alcohols after hydrolysis. Recognizing the mechanism of this reaction is essential for synthesizing ketones like pentan-2-one from esters.
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Nitrile Reactivity
Nitriles are compounds containing the cyano group (-C≡N) and can also react with Grignard reagents. When a Grignard reagent adds to a nitrile, it forms an intermediate imine, which can be hydrolyzed to yield a ketone. This pathway is significant for synthesizing ketones, providing an alternative route to the desired product.
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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
Show how you would add a Grignard reagent to an ester or a nitrile to synthesize
(b) heptan-4-ol.
3
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Textbook Question
Show how Friedel–Crafts acylation might be used to synthesize the following compounds.
a. acetophenone
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Textbook Question
Show how Friedel–Crafts acylation might be used to synthesize the following compounds.
b. benzophenone
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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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