Textbook Question
Use the four compounds shown below to answer the following questions:
b. Why is o-fluorobenzoic acid the weakest of the ortho-halo-substituted benzoic acids?
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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 65h
Show how the following compounds can be synthesized from benzene:
h. p-nitro-N-methylaniline
Verified step by step guidance1
Step 1: Begin with benzene as the starting material. The first step is to introduce a nitro group (-NO₂) onto the benzene ring. This can be achieved through an electrophilic aromatic substitution reaction called nitration. Use a mixture of concentrated H₂SO₄ (sulfuric acid) and HNO₃ (nitric acid) to generate the nitronium ion (NO₂⁺), which acts as the electrophile. This reaction will yield nitrobenzene.
Step 2: Reduce the nitro group (-NO₂) on nitrobenzene to an amino group (-NH₂). This can be done using a reducing agent such as Sn (tin) and HCl, or Fe (iron) and HCl, followed by neutralization with a base. The product of this step is aniline (C₆H₅NH₂).
Step 3: Protect the amino group (-NH₂) on aniline to prevent unwanted side reactions during subsequent steps. This can be done by acetylation, where aniline reacts with acetic anhydride (CH₃CO)₂O to form acetanilide (C₆H₅NHCOCH₃).
Step 4: Introduce a methyl group (-CH₃) onto the nitrogen atom of the protected amino group. This can be achieved by reacting acetanilide with methyl iodide (CH₃I) in the presence of a base such as K₂CO₃. This step forms N-methylacetanilide.
Step 5: Hydrolyze the N-methylacetanilide to remove the acetyl protecting group and regenerate the free amino group. This can be done using aqueous acid or base. Finally, introduce a para-nitro group (-NO₂) onto the benzene ring of N-methylaniline through nitration (as described in Step 1), ensuring the nitro group is directed to the para position due to the electron-donating nature of the N-methyl group.
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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, such as benzene. This process is crucial for synthesizing various derivatives of benzene, including p-nitro-N-methylaniline. Understanding the mechanism of EAS, including the role of catalysts and the stability of intermediates, is essential for predicting the outcomes of reactions involving aromatic compounds.
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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 p-nitro-N-methylaniline from benzene.
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Reduction of Nitro Compounds
The reduction of nitro compounds is a key transformation in organic synthesis, where a nitro group is converted into an amine. This process can be achieved using various reducing agents, such as iron and hydrochloric acid or catalytic hydrogenation. Understanding the reduction mechanism is important for synthesizing p-nitro-N-methylaniline, as it involves the conversion of the nitro group to an amino group, which is essential for the final product.
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Related Practice
Textbook Question
a. Rank the following esters from most reactive to least reactive in the first slow step of a nucleophilic acyl substitution reaction (formation of the tetrahedral intermediate):
Textbook Question
Use the four compounds shown below to answer the following questions:
a. Why are the ortho-halo-substituted benzoic acids stronger acids than benzoic acid?
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Textbook Question
Show how the following compounds can be synthesized from benzene:
g. p-dideuteriobenzene
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Textbook Question
An aromatic hydrocarbon with a molecular formula of C13H20 has an 1H NMR spectrum with a signal at ~7 ppm that integrates to 5H. It also has two singlets; one of the singlets has 1.5 times the area of the second. What is the structure of the aromatic hydrocarbon?
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Textbook Question
Show how the following compounds can be synthesized from benzene:
a. N,N,N-trimethylanilinium iodide
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