Which compound amongst the following is not an aromatic compound?

Which compound amongst the following is not an aromatic compound?
  1.    

  2.  

  3.    

  4.    

Solution

 German chemist and physicist Erich Hückel proposed a theory to help determine if a planar ring molecule would have aromatic properties. His rule states that if a cyclic, planar molecule has 4n+2 π electrons, it is considered aromatic. This rule would come to be known as Hückel's Rule

   

In the above molecule,There is an sp3 hybridized carbon in the ring.Hence, it is not involved in conjugation. As delocalization of π electrons is not there throughout the ring.It is not an aromatic species.

It does not follow Huckel's rule.

But in the other options the species given that is ,andare aromatic as they obey Huckel's rule

 

Asked in: NEET 2022 (Phase 1)

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