Core - Organic Chemistry

Chapter 18

Reactions of Aromatic Compounds

18.1 : NMR Spectroscopy of Benzene Derivatives

18.1 : NMR Spectroscopy of Benzene Derivatives

Simple unsubstituted benzene has six aromatic protons, all chemically equivalent. Therefore, benzene exhibits only a singlet peak at δ 7.3 ppm ...

18.2 : Reactions at the Benzylic Position: Oxidation and Reduction

18.2 : Reactions at the Benzylic Position: Oxidation and Reduction

The benzylic position describes the position of a carbon atom attached directly to a benzene ring. Benzene by itself does not undergo oxidation. In ...

18.3 : Reactions at the Benzylic Position: Halogenation

18.3 : Reactions at the Benzylic Position: Halogenation

Benzylic halogenation takes place under conditions that favor radical reactions such as heat, light, or a free radical initiator like peroxide. The ...

18.4 : Electrophilic Aromatic Substitution: Overview

18.4 : Electrophilic Aromatic Substitution: Overview

In an electrophilic aromatic substitution reaction, an electrophile substitutes for a hydrogen of an aromatic compound. Many functional groups can be ...

18.5 : Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene

18.5 : Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene

Chlorination and bromination are important classes of electrophilic aromatic substitutions, where benzene reacts with chlorine or bromine in the presence ...

18.6 : Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene

18.6 : Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene

Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are ...

18.7 : Electrophilic Aromatic Substitution: Nitration of Benzene

18.7 : Electrophilic Aromatic Substitution: Nitration of Benzene

The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the ...

18.8 : Electrophilic Aromatic Substitution: Sulfonation of Benzene

18.8 : Electrophilic Aromatic Substitution: Sulfonation of Benzene

Sulfonation of benzene is a reaction wherein benzene is treated with fuming sulfuric acid at room temperature to produce benzenesulfonic acid. Fuming ...

18.9 : Electrophilic Aromatic Substitution: Friedel–Crafts Alkylation of Benzene

18.9 : Electrophilic Aromatic Substitution: Friedel–Crafts Alkylation of Benzene

Friedel–Crafts reactions were developed in 1877 by the French chemist Charles Friedel and the American chemist James Crafts. Friedel–Crafts ...

18.10 : Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene

18.10 : Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene

The Friedel–Crafts acylation reactions involve the addition of an acyl group to an aromatic ring. These reactions proceed via electrophilic aromatic ...

18.11 : Limitations of Friedel–Crafts Reactions

18.11 : Limitations of Friedel–Crafts Reactions

Several restrictions limit the use of Friedel–Crafts reactions. First, the halogen in the alkyl halide must be attached to an sp3-hybridized carbon ...

18.12 : Directing Effect of Substituents: <em>ortho</em>–<em>para</em>-Directing Groups

18.12 : Directing Effect of Substituents: ortho–para-Directing Groups

Ortho–para directors are substituent groups attached to the benzene ring and direct the addition of an electrophile to the positions ortho or para ...

18.13 : Directing Effect of Substituents: <em>meta</em>-Directing Groups

18.13 : Directing Effect of Substituents: meta-Directing Groups

Substituents on the benzene ring that direct an incoming electrophile to undergo substitution at the meta position are ...

18.14 : <em>ortho</em>–<em>para</em>-Directing Activators: –CH<sub>3</sub>, –OH, –&NoBreak;NH<sub>2</sub>, –OCH<sub>3</sub>

18.14 : ortho–para-Directing Activators: –CH₃, –OH, –⁠NH₂, –OCH₃

All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons ...

18.15 : <em>ortho</em>–<em>para</em>-Directing Deactivators: Halogens

18.15 : ortho–para-Directing Deactivators: Halogens

Halogens are ortho–para directors. They are more electronegative than carbon. Therefore, as ring substituents, they can withdraw electrons through ...

18.16 : <em>meta</em>-Directing Deactivators: –NO<sub>2</sub>, –CN, –CHO, –&NoBreak;CO<sub>2</sub>R, –COR, –CO<sub>2</sub>H

18.16 : meta-Directing Deactivators: –NO₂, –CN, –CHO, –⁠CO₂R, –COR, –CO₂H

All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive ...

18.17 : Directing and Steric Effects in Disubstituted Benzene Derivatives

18.17 : Directing and Steric Effects in Disubstituted Benzene Derivatives

When disubstituted benzenes undergo electrophilic substitution, the product distribution depends on the directing effect of both substituents. When the ...

18.18 : Nucleophilic Aromatic Substitution: Addition–Elimination (S<sub>N</sub>Ar)

18.18 : Nucleophilic Aromatic Substitution: Addition–Elimination (S_NAr)

Nucleophilic substitution in aromatic compounds is feasible in substrates bearing strong electron-withdrawing substituents positioned ortho or para to the ...

18.19 : Nucleophilic Aromatic Substitution: Elimination–Addition

18.19 : Nucleophilic Aromatic Substitution: Elimination–Addition

Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as ...

18.20 : Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic S<sub>N</sub>1

18.20 : Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic S_N1

Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The ...

18.21 : Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation

18.21 : Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation

Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take ...

18.22 : Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism

18.22 : Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism

Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of ...

18.23 : Hydrolysis of Chlorobenzene to Phenol: Dow Process

18.23 : Hydrolysis of Chlorobenzene to Phenol: Dow Process

Simple aryl halides do not react with nucleophiles under normal conditions. However, the reaction can proceed under drastic conditions involving high ...

18.24 : Benzene to Phenol via Cumene: Hock Process

18.24 : Benzene to Phenol via Cumene: Hock Process

The synthesis of phenol from benzene via cumene and cumene hydroperoxide is called the Hock process. First, a Friedel–Crafts alkylation reaction of ...

18.25 : Oxidation of Phenols to Quinones

18.25 : Oxidation of Phenols to Quinones

In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The ...

Copyright © 2023 MyJoVE Corporation. All rights reserved