S'identifier

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 ...

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