I was just studying organic chemistry and came across a weird, yet beautiful, structure, don't know its name but its structure is given below:

                                               my own drawing!!

I wanted to ask what is the compound's name? Is it aromatic, anti-aromatic, or non-aromatic? I guess it should be anti-aromatic as it is not following Huckel's Rule, ig? as total of $16$ $\pi$ electrons are there, so it should be having $4n$ electrons where $n = 4$. But anti-aromatic compounds are highly unstable to the extent that they doesn't exist, but this compound seems stable to me!


1 Answer 1


The given compound is Pyrene. Pyrene is a polycyclic aromatic hydrocarbon consisting of four fused benzene rings, resulting in a flat aromatic system. The chemical formula is $C_{16}H_{10}$.

Pyrene is aromatic. The Huckel $(4n+2)π$ rule works best with monocyclic ring systems. If you look at the following resonance structure for pyrene with a central double bond, the monocyclic periphery has 14 π electrons (ignoring the greyed-out central double bond), but that is a rationalization.

Nonetheless, pyrene undergoes reactions characteristic of aromatic systems and has ring currents expected from aromatic systems.

The $(4n+2)π$ rule was really meant to apply to monocyclic pi systems. You run into problems when it is extended beyond its originally intended use.

  • 1
    $\begingroup$ Hmmm, but I can't understand how there are 14 pi electrons? $\endgroup$
    – Gamin8ing
    Commented Sep 29, 2021 at 5:58
  • 2
    $\begingroup$ @Gamin8ing the path around the perimeter gives you 14 π electrons. The huckle rule will be followed if the central two carbons aren't aromatic. But it is controversial. $\endgroup$
    – R_Squared
    Commented Sep 29, 2021 at 6:16

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