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Chapter 12 : Reactions of Arenes. Electrophilic Aromatic Substitution
Ch 12 contents

Reactions and Reagents

The following table contains a summary of the key reactions to introduce a substituent onto an aromatic system.
More detailed information on each reaction can be accessed by following the link from the reaction column.
Reactions that can be used to convert existing aromatic substituents are listed separately.

Study Tips:
  • The reagent combinations and reaction conditions for reactions of benzenes are usually more severe than reactions of alkenes.... this tends to make them more readily recognisable.  
  • Recognise the electrophile present in the reagent combination.

Reaction
Reagents
Electrophile
Product
Comments
Nitration
HNO3 / H2SO4
NO2+
E+ formed by loss of water from nitric acid
Sulfonation
H2SO4 or SO3 / H2SO4
SO3
Reversible (heat with aq. acid)
Halogenation
Cl2 / Fe or FeCl3
Cl+
E+ formed by Lewis acid removing Cl
Br2 / Fe or FeBr3
Br+
E+ formed by Lewis acid removing Br-
Alkylation
R-Cl / AlCl3
R+
E+ formed by Lewis acid removing Cl-
R-OH / H+
R+
E+ formed by loss of water from alcohol
C=C / H+
R+
E+ formed by protonation of alkene
Acylation
RCOCl / AlCl3
  RCO+
E+ formed by Lewis acid removing Cl-
RCO2COR / AlCl3
 RCO+
E+ formed by Lewis acid removing RCO2-

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organic chemistry © Dr. Ian Hunt, Department of Chemistry University of Calgary