Textbook Question
a. Does a coupling reaction have to be used to synthesize p-dipropylbenzene?
b. Can a coupling reaction be used to synthesize p-dipropylbenzene?
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Ch. 18 - Reactions of Benzene and Substituted Benzenes
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
Chapter 19, Problem 21c,d
Give the products, if any, of each of the following reactions:
c. benzoic acid + CH3CH2Cl + AlCl3
d. benzene + 2 CH3Cl + AlCl3
Verified step by step guidance1
Step 1: Recognize the type of reaction. Both reactions involve a benzene ring and a reagent with an alkyl halide (R-Cl) in the presence of AlCl3, which is a Lewis acid catalyst. This suggests that these are Friedel-Crafts reactions, specifically alkylation reactions.
Step 2: For reaction (c), benzoic acid + CH3CH2Cl + AlCl3: Understand that the carboxylic acid group (-COOH) on benzoic acid is an electron-withdrawing group. This deactivates the benzene ring and makes it less reactive toward electrophilic aromatic substitution reactions like Friedel-Crafts alkylation. Therefore, no reaction occurs in this case.
Step 3: For reaction (d), benzene + 2 CH3Cl + AlCl3: The first step involves the generation of the electrophile. AlCl3 reacts with CH3Cl to form a methyl carbocation (CH3⁺), which is the electrophile in this reaction. This is represented as: CH3Cl + AlCl3 → CH3⁺ + AlCl4⁻.
Step 4: The methyl carbocation (CH3⁺) reacts with the benzene ring in an electrophilic aromatic substitution reaction. The benzene ring donates a pair of π-electrons to the CH3⁺, forming a sigma complex (arenium ion). This intermediate then loses a proton (H⁺) to regenerate the aromaticity of the benzene ring, resulting in toluene (methylbenzene).
Step 5: The second CH3Cl molecule can undergo the same process, leading to the formation of a second methyl group on the benzene ring. The position of the second methyl group will depend on the directing effects of the first methyl group. Since the methyl group is an electron-donating group, it is an ortho/para director. Therefore, the final product will be a mixture of ortho-xylene and para-xylene.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Friedel-Crafts Alkylation
Friedel-Crafts alkylation is a reaction that introduces alkyl groups into an aromatic ring using an alkyl halide and a Lewis acid catalyst, such as AlCl3. The Lewis acid activates the alkyl halide, generating a more reactive carbocation that can then attack the aromatic system. This reaction is crucial for synthesizing substituted aromatic compounds.
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Friedel-Crafts Alkylation
Electrophilic Aromatic Substitution
Electrophilic aromatic substitution (EAS) is a fundamental reaction mechanism in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. The aromatic system donates electrons to the electrophile, forming a sigma complex, which then loses a proton to restore aromaticity. Understanding EAS is essential for predicting the outcomes of reactions involving aromatic compounds.
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Reactivity of Alkyl Halides
The reactivity of alkyl halides in electrophilic aromatic substitution depends on the structure of the alkyl group and the leaving group. Primary alkyl halides tend to react via a carbocation mechanism, while tertiary halides can stabilize carbocations more effectively. This concept is important for determining the products of reactions involving alkyl halides and aromatic compounds.
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Related Practice
Textbook Question
Show how the following compounds can be synthesized from benzene:
a.
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Textbook Question
Show how the following compounds can be synthesized from benzene:
b.
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Textbook Question
What products are obtained from the reaction of the following compounds with one equivalent of Br2, using FeBr3 as a catalyst?
c.
d.
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Textbook Question
What products are obtained from the reaction of the following compounds with one equivalent of Br2, using FeBr3 as a catalyst?
b.
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Textbook Question
Give the products, if any, of each of the following reactions:
a. benzonitrile + methyl chloride + AlCl3
b. phenol + Br2
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