Question

Pyridine is less basic than triethylamine because:

• A. Pyridine has aromtic character
• B. Nitrogen in pyridine is sp${}^2$ hybridised
• C. Pyridine is a cyclic system
• D. In pyridine, lone pair of nitrogen is delocalised

Answer 1

The correct option is B Nitrogen in pyridine is sp${}^2$ hybridised

Pyridine, is much less basic than typical aliphatic amines, but for a very different reason: the unshared pair is in an sp${}^2$, which is much lower in energy than the electron pair of aliphatic amines, which is in an sp${}^3$. Therefore, pyridine is less easily protonated than typical aliphatic amines such as triethylamine.