Which of following is not heterocyclic aromatic compound ?A Melamine B Azulene C Pyridine D Furan

To determine which of the following compounds is not a heterocyclic aromatic compound, we need to understand the characteristics of heterocyclic aromatic compounds.

Heterocyclic aromatic compounds are organic compounds that contain a ring structure with at least one heteroatom, which is an atom other than carbon, such as nitrogen, oxygen, or sulfur. These compounds exhibit aromaticity, meaning they have a stable, cyclic, and planar structure with delocalized pi electrons.

Let's analyze each option:

A) Melamine: Melamine is a heterocyclic compound that contains a ring structure with three nitrogen atoms. It is considered a heterocyclic aromatic compound.

B) Azulene: Azulene is a bicyclic compound that contains a five-membered ring fused to a seven-membered ring. It is also considered a heterocyclic aromatic compound.

C) Pyridine: Pyridine is a heterocyclic compound that contains a six-membered ring with one nitrogen atom. It is a classic example of a heterocyclic aromatic compound.

D) Furan: Furan is a heterocyclic compound that contains a five-membered ring with one oxygen atom. It is also considered a heterocyclic aromatic compound.

Based on the analysis, all of the options A, B, C, and D are heterocyclic aromatic compounds. Therefore, none of them is not a heterocyclic aromatic compound.

In conclusion, there is no compound among the options provided that is not a heterocyclic aromatic compound.