Textbook Question
Show how Friedel–Crafts acylation might be used to synthesize the following compounds.
c. n-butylbenzene
3
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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 32a,b
Show how you would use anhydrides to synthesize the following compounds. In each case, explain why an anhydride might be preferable to an acid chloride.
(a) n-octyl formate
(b) n-octyl acetate
Verified step by step guidance1
Step 1: Understand the structure of the target compounds. (a) n-octyl formate is an ester with the formula CH3(CH2)6CH2OCHO, where the alcohol component is n-octanol and the acid component is formic acid. (b) n-octyl acetate is an ester with the formula CH3(CH2)6CH2OCOCH3, where the alcohol component is n-octanol and the acid component is acetic acid.
Step 2: Recall the general reaction mechanism for ester synthesis using anhydrides. Anhydrides react with alcohols to form esters and a carboxylic acid byproduct. This reaction is typically preferred over using acid chlorides because anhydrides are less reactive, easier to handle, and do not produce corrosive HCl as a byproduct.
Step 3: For (a) n-octyl formate, use formic anhydride (HCO)2O as the starting anhydride. React n-octanol (CH3(CH2)6CH2OH) with formic anhydride. The reaction proceeds via nucleophilic attack of the alcohol oxygen on the carbonyl carbon of the anhydride, followed by elimination of formic acid (HCOOH) as the byproduct.
Step 4: For (b) n-octyl acetate, use acetic anhydride (CH3CO)2O as the starting anhydride. React n-octanol (CH3(CH2)6CH2OH) with acetic anhydride. The reaction mechanism is similar to (a), where the alcohol oxygen attacks the carbonyl carbon of the anhydride, leading to the formation of n-octyl acetate and acetic acid (CH3COOH) as the byproduct.
Step 5: Summarize why anhydrides are preferable to acid chlorides. Anhydrides are less reactive than acid chlorides, making them easier to control in reactions. They do not produce corrosive HCl, which can be problematic in certain reaction setups. Additionally, the byproducts (formic acid or acetic acid) are less hazardous and easier to handle compared to HCl.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Anhydrides in Organic Synthesis
Anhydrides are reactive compounds derived from acids by the removal of water. They are commonly used in organic synthesis due to their ability to acylate nucleophiles, forming esters or amides. Their reactivity allows for the formation of carbon-carbon bonds, making them versatile intermediates in the synthesis of various organic compounds.
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03:35
Anhydride Nomenclature
Comparison of Anhydrides and Acid Chlorides
While both anhydrides and acid chlorides are acylating agents, anhydrides are often preferred due to their milder reactivity and lower toxicity. Acid chlorides can be more reactive, leading to side reactions or decomposition, whereas anhydrides can provide better control over the reaction conditions, resulting in higher yields of the desired product.
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Synthesis of Esters
The synthesis of esters from alcohols and acylating agents like anhydrides involves a nucleophilic acyl substitution mechanism. In this process, the alcohol acts as a nucleophile, attacking the carbonyl carbon of the anhydride, leading to the formation of the ester and a carboxylic acid. Understanding this mechanism is crucial for predicting the outcomes of the reactions in the given synthesis tasks.
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Related Practice
Textbook Question
Suggest the most appropriate reagent for each synthesis, and explain your choice.
(b)
2
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Textbook Question
Show how you would use anhydrides to synthesize the following compounds. In each case, explain why an anhydride might be preferable to an acid chloride.
(c) phthalic acid monoamide
(d) succinic acid monomethyl ester
2
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Textbook Question
Show how Friedel–Crafts acylation might be used to synthesize the following compounds.
a. acetophenone
1
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Textbook Question
Suggest the most appropriate reagent for each synthesis, and explain your choice.
(a)
1
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Textbook Question
Show how Friedel–Crafts acylation might be used to synthesize the following compounds.
b. benzophenone
8
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