Why is furan an aromatic compound?

1 Answer

Furan is an aromatic compound because one of the lone pairs of electrons on the oxygen atom is delocalized into the ring.

Orbital structures of electrons from wps.prenhall.com.

The oxygen atom is sp² hybridized, with one of its lone pairs in a p orbital.

This creates a cyclic π system with six electrons.

According to Hückel's 4n+2 rule, this is an aromatic π system.