Introductory Chapter: Pyridine

Pyridine (C5H5N), an aromatic compound where all the pi electrons are shared by a ring, forms one continuous circle of electrons besides the alternate double bonds shared by every atom on the circle. Pyridine is a unique type with nitrogen on the ring to provide a tertiary amine by undergoing reactions such as alkylation and oxidation. Amine is responsible for the slight dipole on the ring because electrons are drawn more toward the nitrogen being electronegative (lone pair electrons on the nitrogen) than other atoms in the ring. The H nuclear magnetic radiation (H-NMR) shows three signals at the ortho, meta, and para positions on the molecule in respect of three different chemical shifts. These chemical shifts are the result of the different electron densities for each of these atoms. As a result, this is not stable as other aromatic compounds (Figure 1).