Question

Is pyridine an aromatic compound?

Answer 1

Hint :A compound is said to be aromatic if it is flat, cyclic and conjugated and also obeys Huckel’s rule. Huckel's rule states that an organic compound should have pi electrons in the overlapping $p$ orbitals in order to be aromatic.

Complete Step By Step Answer:
The $\pi$ orbital system of pyridine has $p$ electrons which are delocalized throughout the ring. It also has $4n+2$ delocalized $p$ electrons, where $n=1$ . Pyridine is planar as all of its $p$ orbitals are perpendicular to the ring. Also, it is a cyclic compound. It matches all the qualifications of an aromatic compound. So, pyridine is an aromatic compound. The structure of pyridine is given below:

The lone pair on the nitrogen atom does not take place in delocalization and is not considered when counting the number of $\pi$ electrons. Pyridine is an aromatic compound containing an amine. Aromatic compounds are considered very stable and they can only undergo reactions if the end product keeps the aromaticity of the ring. The aromatic compound pyridine has three resonance structures.
Therefore, pyridine is an aromatic compound.

Note :
The nitrogen present in pyridine creates a tertiary amine which is able to undergo alkylation and oxidation reactions. This amine causes a dipole on the ring, so it is not stable as other aromatic compounds like benzene. The dipole is the effect of more electrons being drawn towards the nitrogen atom instead of being shared equally with all the atoms present. This happens because of the fact that the nitrogen atom is more electronegative than the carbon atom.