Electriphilic Substitution in Furan

Furan undergoes electrophilic substitution reactions at position C-2.

i. Halogenation: Furan reacts with halogens [X2, Where X2= Cl2, Br2 And I2] to give 2-halofuran. For example, the reaction of bromine with furan gives 2-bromofuran.

ii. Nitration: Nitration of furan is achieved by reacting it with HNO3 in acetic anhydride. The reaction of HNO3 and anhydride resulted in acetyl nitrate in which -NO2 acts as an electrophile.

iii. Sulphonation: Sulphonation of Furan is achieved by reacting it with sulfur trioxide (SO3)- pyridine mixture in ethylene chloride at 100° C.

iv. Friedel-Crafts Acylation: Reaction of furan with acetic anhydride in presence of BF3 gives 2-acetyl furan.