Electrophilic Aromatic Substitution Reaction

Electrophilic Aromatic Substitution Reaction


Electrophilic aromatic substitution

·         Nitration

·         Sulphonation

·         Halogenation 

Nitration of Benzene 

       A nitro group (-NO2 ) substitutes for a hydrogen

       Nitration of benzene with nitric acid requires sulfuric acid as a catalyst


       Step I  Generation of electrophile

        Step 2  Attack of electrophile leads to formation of sigma complex or wheland complex which is resonance stabilized

       Resonance stabilization of  wheland complex

       Step 3  Loss of a proton gives nitrobenzene


       Nitration is a electrophilic aromatic substitution reaction

       Nitro group is getting introduced in benzene

       Nitronium ion  acts as electrophile in nitration

       Nitrating mixture is used for nitration

       Sulphur  trioxide is a neutral electrophile

       Benzene on sulphonation gives benzene sulphonic acid

       For halogenation reaction ferric bromide or ferric chloride is used

       Ferric bromide or ferric chloride  forms a complex with halogen

       But it can act as nucleophile

       Sulphonation leads to formation of benzene sulphonic  acid

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