Question

A compound with molecular formula $C_4{H}_{4}O$ has all the four carbon atoms and the oxygen atom in the ring. It also has two double bonds. The compound is

• A. homocyclic and aromatic
• B. heterocyclic and aromatic
• C. homocyclic but not aromatic
• D. heterocyclic but not aromatic.

Answer 1

Answer: (B)

Furan is heterocyclic and aromatic. Here $O$ is $s{p}^2$ hybridised. One lone pair is present in the unhybridised orbital, while the other is present in hybridised $s{p}^2$-orbital. The lone pair present in the unhybridised $p$-orbital takes part in $p\pi -p\pi$ bonding. Thus, there are six $\pi$-electrons and as such it is aromatic