Electrophilic Substitution in Pyrrole (Reactivity and Orientation)

Pyrrole, thiophene, and furan gives electrophilic aromatic substitution reaction. These compounds are more reactive compared to benzene. Electrophiles majorly attack on 2^nd position rather than 3^rd position in these heterocyclic compounds. The reason behind it is the more number of resonating intermediate structure are possible to accommodate the positive charge when electrophile attacks on 2^nd position (three resonating intermediate structures) that makes the intermediate carbocation more stable while if electrophile attacks on the 3^rd position then only two resonating intermediate structures are possible as shown in the figure which is comparitively less stable. That’s why the attack of electrophiles takes place at 2^nd position in pyrrole, thiophene, and furan.