Q15-4P - Organic Chemistry (Mcmurry)

Question

Pyridine is a flat, hexagonal molecule with bond angles of 120°. It undergoes substitution rather than addition and generally behaves like benzene. Draw a picture of the orbitals of pyridine to explain its properties. Check your answer by looking ahead to Sections 15-5.

Step-by-Step Solution

Answer

Pi orbitals of pyridine are as follows.

Step 1: Pyridine

Pyridine is a heterocyclic aromatic compound, the N is the heteroatom present in the ring with one lone pair and it is basic in nature with the molecular formula ${\mathbf{\text{C}}}_{\mathbf{5}}{\mathbf{\text{H}}}_{\mathbf{5}}\mathbf{\text{N}}$.

Step 2: π Orbitals of Pyridine

Like benzene, pyridine also has an aromatic structure with three double bonds which have the pi electrons in the p orbital and show delocalization, and lone pair of nitrogen is ${\text{C}}_8{{\text{H}}_8}^{2-}$ which occupies the plane in the pyridine ring. It is formed by the sigma overlap of carbon and ${\text{sp}}^2$of nitrogen as shown below.

Step 3: Properties of Pyridine

1. Highly flammable.
2. Basic nature.
3. Weekly alkaline.
4. Water miscible liquid.
5. Smell like fish