# Is thiophene an aromatic?

Apr 28, 2015

Yes, thiophene is an aromatic compound.

According to Hückel's rule, a planar, conjugated, cyclic molecule is aromatic if it has $4 n + 2$ π electrons. The value of $n$ can be zero or any positive integer.

The most common aromatic molecule is benzene ($n = 1$).

Pyrrole, furan, and thiophene are other aromatic compounds with $n = 1$.

The heteroatoms each contribute two electrons to the π system.

However, the resonance stabilization in thiophene (122 kJ/mol) is less than that in benzene (152 kJ/mol), because $\text{S}$ is more electronegative than $\text{C}$.

$\text{S}$ is less "willing" to donate its electrons to the aromatic system.

But, because thiophene is aromatic, it does not have the properties of ordinary thioethers.