Anmelden

Kapitel 18

Reaktionen von aromatischen Verbindungen

NMR-Spektroskopie von Benzol-Derivaten
NMR-Spektroskopie von Benzol-Derivaten
Simple unsubstituted benzene has six aromatic protons, all chemically equivalent. Therefore, benzene exhibits only a singlet peak at δ 7.3 ppm ...
Reaktionen an der benzylischen Position: Überblick
Reaktionen an der benzylischen Position: Überblick
The benzylic position describes the position of a carbon atom attached directly to a benzene ring. Benzene by itself does not undergo oxidation. In ...
Reaktionen an der benzylischen Position: Halogenierung
Reaktionen an der benzylischen Position: Halogenierung
Benzylic halogenation takes place under conditions that favor radical reactions such as heat, light, or a free radical initiator like peroxide. The ...
Elektrophile aromatische Substitution: Überblick
Elektrophile aromatische Substitution: Überblick
In an electrophilic aromatic substitution reaction, an electrophile substitutes for a hydrogen of an aromatic compound. Many functional groups can be ...
Elektrophile aromatische Substitution: Chlorierung und Bromierung von Benzol
Elektrophile aromatische Substitution: Chlorierung und Bromierung von Benzol
Chlorination and bromination are important classes of electrophilic aromatic substitutions, where benzene reacts with chlorine or bromine in the presence ...
Elektrophile aromatische Substitution: Fluorierung und Iodierung von Benzol
Elektrophile aromatische Substitution: Fluorierung und Iodierung von Benzol
Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are ...
Elektrophile aromatische Substitution: Nitrierung von Benzol
Elektrophile aromatische Substitution: Nitrierung von Benzol
The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the ...
Elektrophile aromatische Substitution: Sulfonierung von Benzol
Elektrophile aromatische Substitution: Sulfonierung von Benzol
Sulfonation of benzene is a reaction wherein benzene is treated with fuming sulfuric acid at room temperature to produce benzenesulfonic acid. Fuming ...
Elektrophile aromatische Substitution: Friedel-Crafts-Alkylierung von Benzol
Elektrophile aromatische Substitution: Friedel-Crafts-Alkylierung von Benzol
Friedel–Crafts reactions were developed in 1877 by the French chemist Charles Friedel and the American chemist James Crafts. Friedel–Crafts ...
Elektrophile aromatische Substitution: Friedel-Crafts-Acylierung von Benzol
Elektrophile aromatische Substitution: Friedel-Crafts-Acylierung von Benzol
The Friedel–Crafts acylation reactions involve the addition of an acyl group to an aromatic ring. These reactions proceed via electrophilic aromatic ...
Grenzen der Friedel-Crafts-Reaktionen
Grenzen der Friedel-Crafts-Reaktionen
Several restrictions limit the use of Friedel–Crafts reactions. First, the halogen in the alkyl halide must be attached to an sp3-hybridized carbon ...
Dirigierende Wirkung von Substituenten: ortho-para-dirigierende Gruppen
Dirigierende Wirkung von Substituenten: ortho-para-dirigierende Gruppen
Ortho–para directors are substituent groups attached to the benzene ring and direct the addition of an electrophile to the positions ortho or para ...
Dirigierende Wirkung von Substituenten: meta-dirigierende Gruppen
Dirigierende Wirkung von Substituenten: meta-dirigierende Gruppen
Substituents on the benzene ring that direct an incoming electrophile to undergo substitution at the meta position are ...
ortho-para-dirigierende Aktivatoren: -CH3, -OH, -NH2, -OCH3
ortho-para-dirigierende Aktivatoren: -CH3, -OH, -NH2, -OCH3
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons ...
<em>ortho</em>–<em>para-Directing</em> Deaktivatoren: Halogene
orthopara-Directing Deaktivatoren: Halogene
Halogens are ortho–para directors. They are more electronegative than carbon. Therefore, as ring substituents, they can withdraw electrons through ...
meta-dirigierende Deaktivatoren: -NO2, -CN, -CHO, -CO2R, -COR, -CO2H
meta-dirigierende Deaktivatoren: -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 ...
Dirigierende und sterische Effekte in disubstituierten Benzol-Derivaten
Dirigierende und sterische Effekte in disubstituierten Benzol-Derivaten
When disubstituted benzenes undergo electrophilic substitution, the product distribution depends on the directing effect of both substituents. When the ...
Nukleophile Aromatische Substitution: Addition-Eliminierung (SNAr)
Nukleophile Aromatische Substitution: Addition-Eliminierung (SNAr)
Nucleophilic substitution in aromatic compounds is feasible in substrates bearing strong electron-withdrawing substituents positioned ortho or para to the ...
Nukleophile aromatische Substitution: Eliminierung-Addition
Nukleophile aromatische Substitution: Eliminierung-Addition
Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as ...
Nukleophile aromatische Substitution von Aryldiazoniumsalzen: Aromatische SN1
Nukleophile aromatische Substitution von Aryldiazoniumsalzen: Aromatische SN1
Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The ...
Reduktion von Benzol zu Cyclohexan: Katalytische Hydrierung
Reduktion von Benzol zu Cyclohexan: Katalytische Hydrierung
Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take ...
Benzol zu 1,4-Cyclohexadien: Birch-Reduktion
Benzol zu 1,4-Cyclohexadien: Birch-Reduktion
Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of ...
Herstellung von Phenolen
Herstellung von Phenolen
Simple aryl halides do not react with nucleophiles under normal conditions. However, the reaction can proceed under drastic conditions involving high ...
Benzol zu Phenol über Kumol: Hock-Verfahren
Benzol zu Phenol über Kumol: Hock-Verfahren
The synthesis of phenol from benzene via cumene and cumene hydroperoxide is called the Hock process. First, a Friedel–Crafts alkylation reaction of ...
Oxidation von Phenolen zu Chinonen
Oxidation von Phenolen zu Chinonen
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The ...
JoVE Logo

Datenschutz

Nutzungsbedingungen

Richtlinien

Forschung

Lehre

ÜBER JoVE

Copyright © 2025 MyJoVE Corporation. Alle Rechte vorbehalten