Question

What is the electrophile in nitration of benzene reaction?

Answer 1

Electrophiles:

• A reagent that takes away an electron pair is called electrophiles and it is represented as $\left(E^{+}\right)$.
• Electrophiles are electron-deficient molecules that attack at nucleophilic centre of the substrate which is an electron-rich molecule.

Nitration of benzene:

• It is an electrophilic substitution reaction in which a nitro group is introduced into benzene ring when it is heated with a mixture of concentrated nitric acid and concentrated sulphuric acid.
• In this reaction, when benzene is treated with concentrated nitric acid and concentrated sulphuric acid, it results in the formation of nitrobenzene.
• The nitration of benzene reaction is shown below in the image.

Mechanism for nitration of benzene:

• Sulfuric acid donates a proton to nitric acid, which subsequently dissociates to produce the nitronium ion $\left({\mathrm{NO}}_2^{+}\right)$.
• The process involves the nitronium ion acting as an electrophile, which then interacts with benzene to produce an arenium ion.
• The Lewis base then absorbs the arenium ion's proton, forming nitrobenzene.

Thus, the electrophile in nitration of benzene reaction is nitronium ion $\left({\mathrm{NO}}_2^{+}\right)$.