Textbook Question
Why isn’t FeBr3 used as a catalyst in the first step of the synthesis of 1,3,5-tribromobenzene?
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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 31d
Show how the following compounds can be synthesized from benzene:
d. m-methylnitrobenzene
Verified step by step guidance1
Step 1: Begin with benzene as the starting material. Benzene is a simple aromatic compound with a planar, cyclic structure and alternating double bonds, making it highly stable and reactive in electrophilic aromatic substitution reactions.
Step 2: Introduce a nitro group (-NO₂) to the benzene ring through a nitration reaction. This is achieved by treating benzene with a mixture of concentrated sulfuric acid (H₂SO₄) and concentrated nitric acid (HNO₃). The reaction generates the nitronium ion (NO₂⁺), which acts as the electrophile. The product is nitrobenzene.
Step 3: Introduce a methyl group (-CH₃) to the meta position relative to the nitro group. Since the nitro group is a meta-directing group due to its electron-withdrawing nature, a Friedel-Crafts alkylation reaction can be used. Treat nitrobenzene with methyl chloride (CH₃Cl) in the presence of a Lewis acid catalyst, such as aluminum chloride (AlCl₃). This will result in the formation of m-methylnitrobenzene.
Step 4: Carefully control the reaction conditions to avoid over-alkylation or side reactions. Ensure that the methyl group is added only once and that the meta position is favored due to the directing effects of the nitro group.
Step 5: Purify the product, m-methylnitrobenzene, using appropriate techniques such as recrystallization or distillation to ensure the desired compound is isolated in high purity.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electrophilic Aromatic Substitution
Electrophilic aromatic substitution (EAS) is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. This process is crucial for synthesizing various substituted aromatic compounds, including nitro and alkyl derivatives. Understanding EAS mechanisms, such as the role of the electrophile and the stability of the intermediates, is essential for predicting the products formed from benzene.
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03:07
EAS Review
Nitration of Aromatic Compounds
Nitration is a specific type of electrophilic aromatic substitution where a nitro group (-NO2) is introduced into an aromatic ring. This reaction typically involves the use of a nitrating mixture, such as concentrated nitric acid and sulfuric acid, to generate the nitronium ion (NO2+), the active electrophile. Recognizing the conditions and regioselectivity of nitration is vital for synthesizing compounds like m-methylnitrobenzene from benzene.
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08:19Intro to Aromaticity
Regioselectivity in Substitution Reactions
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the case of m-methylnitrobenzene synthesis, understanding how the existing methyl group influences the position where the nitro group is added is crucial. The methyl group is an ortho/para-directing group, but due to steric hindrance, the nitro group will preferentially attach at the meta position in this specific synthesis.
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Related Practice
Textbook Question
What is the major product(s) of each of the following reactions?
e. nitration of p-methoxybenzaldehyde
f. nitration of p-tert-butylmethylbenzene
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Textbook Question
What product is formed from the reaction of p-methylphenol with benzenediazonium chloride?
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Textbook Question
Draw the structure of the activated benzene ring and the diazonium ion used in the synthesis of each of the following compounds, whose structures can be found on page 607.
b. methyl orange
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Textbook Question
In the mechanism for electrophilic aromatic substitution with a diazonium ion as the electrophile, why does nucleophilic attack occur on the terminal nitrogen of the diazonium ion rather than on the nitrogen that has the formal positive charge?
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Textbook Question
Explain why a diazonium group on a benzene ring cannot be used to direct an incoming substituent to the meta position.
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