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Nitration of Benzene

nitration of arenes

Reaction type: Electrophilic Aromatic Substitution

Summary.

  • Overall transformation :  Ar-H to Ar-NO2
  • Reagent : for benzene, HNO3 in H2SO4 / heat
  • Electrophilic species :  the nitronium ion (i.e. NO2+) formed by the loss of water from the nitric acid

 
MECHANISM FOR NITRATION OF BENZENE
Step 1:
An acid / base reaction. Protonation of the hydroxy group of the nitric acid. This provides a better leaving group.....
nitration of benzene
Step 2:
Loss of the leaving group, a water molecule provides the nitronium ion, the reactive electrophile.
Step 3:
The electrophilic nitronium ion reacts with the nucleophilic C=C of the arene. This is the rate determining step as it destroys the aromaticity of the arene.
Step 4:
Water functions as a base to remove the proton from the sp3 C bearing the nitro- group and reforms the C=C and the aromatic system.
 

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