Textbook Question
Predict the major products formed when benzene reacts (just once) with the following reagents.
(j) nitric acid + sulfuric acid
2
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Ch. 17 - Reactions of Aromatic Compounds
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 17, Problem 52a
Show how you would synthesize the following compounds, starting with benzene or toluene and any necessary acyclic reagents. Assume para is the major product (and separable from ortho) in ortho, para mixtures.
a. 1-phenyl-1-bromobutane
Verified step by step guidance1
Step 1: Begin with toluene as the starting material. Toluene is benzene with a methyl group attached, which will help in directing the substitution reaction to the para position.
Step 2: Perform a Friedel-Crafts alkylation reaction. React toluene with 1-bromobutane in the presence of a Lewis acid catalyst such as AlCl₃. This will introduce a butyl group at the para position relative to the methyl group on the benzene ring.
Step 3: Oxidize the methyl group on the benzene ring to a carboxylic acid group using a strong oxidizing agent like KMnO₄ under acidic or basic conditions. This step converts the methyl group into a benzoic acid group.
Step 4: Reduce the carboxylic acid group back to a methyl group using a reducing agent such as Zn(Hg) in concentrated HCl (Clemmensen reduction) or H₂ with a palladium catalyst. This step restores the methyl group while retaining the para-substituted butyl group.
Step 5: Brominate the para-substituted butyl group at the benzylic position using N-bromosuccinimide (NBS) in the presence of light or a radical initiator. This introduces a bromine atom at the benzylic position, yielding 1-phenyl-1-bromobutane as the final product.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electrophilic Aromatic Substitution (EAS)
Electrophilic Aromatic Substitution 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 aromatic compounds, as it allows for the introduction of different functional groups onto the benzene or toluene starting materials. Understanding the mechanism of EAS, including the formation of the sigma complex and the role of the electrophile, is essential for predicting the products of reactions involving aromatic compounds.
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EAS Review
Regioselectivity in Substitution Reactions
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others. In the context of EAS, substituents on the aromatic ring can direct incoming electrophiles to specific positions, such as ortho or para. In this question, the assumption that para is the major product indicates that the directing effects of the substituents must be considered, as they influence the outcome of the synthesis and the separation of isomers.
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Synthesis of Alkyl Halides
The synthesis of alkyl halides involves the introduction of a halogen atom into an alkane or alkyl group, often through reactions such as free radical halogenation or nucleophilic substitution. In the case of synthesizing 1-phenyl-1-bromobutane, understanding how to effectively convert the alkyl chain into a bromide is essential. This may involve using reagents like phosphorus tribromide (PBr3) or other halogenating agents to achieve the desired product while considering the stability and reactivity of the intermediates formed during the reaction.
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Related Practice
Textbook Question
Predict the major products formed when benzene reacts (just once) with the following reagents.
(i) iodine + HNO3
Textbook Question
Predict the major products of the following reactions.
(a) 2,4-dinitrochlorobenzene + NaOCH3
2
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Textbook Question
Predict the major products formed when benzene reacts (just once) with the following reagents.
(k) carbon monoxide, HCl, and AlCl3/CuCl
(l) CH2(COCl)2, AlCl3
2
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Textbook Question
Predict the major products of the following reactions.
(b) phenol + tert-butyl chloride + AlCl3
4
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Textbook Question
Show how you would synthesize the following compounds, starting with benzene or toluene and any necessary acyclic reagents. Assume para is the major product (and separable from ortho) in ortho, para mixtures.
b. 1-phenyl-1-methoxybutane
1
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