Q9P - Organic Chemistry (Mcmurry)

Question

Draw an orbital picture of furan to show how the molecule is aromatic.

Step-by-Step Solution

Answer

The orbital picture of furane is shown below.

Step-by-Step Solution Step 1: Furan

Furan is a heterocyclic five-membered aromatic compound. The O is the heteroatom present in the ring with two lone pairs and it is basic in nature with two double bonds which show delocalization with lone pair of oxygen.

Step 2: π orbitals of furan

Furane has 2 double bonds, so 4 π electrons are present in the p orbital of the carbon and one lone pair of oxygen takes part in delocalization of the pi electrons. The lone pair localized does not take part in delocalization and the orbitals are present perpendicular to the plane of the ring as shown below.

                                       Molecular Orbitals of Furan

Step 3: Aromatic nature of furan

As furane has 4 pi electrons due to 2 double bonds and 1 lone pair of oxygen, the 2 electrons also take part in delocalization. So, for delocalization, furan has 6 electrons and as per 4n+2 rule, n=1 which is a whole number. We can conclude from this that furane is aromatic in nature.