Pyridine is less basic than triethylamine because (a)...

Pyridine is less basic than triethylamine because
(a) pyridine has aromatic character
(b) nitrogen in pyridine is $\mathrm{sp}^2$ hybridised
(c) pyridine is a cyclic system
(d) in pyridine, lone pair of nitrogen is delocalised.

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Key Concepts

Basicity of Amines

The basicity of amines is determined by the availability of the nitrogen’s lone pair to bind a proton. Factors influencing this availability include both the electronic environment and the type of hybridization at the nitrogen atom, which affect how strongly the lone pair is held and thus its reactivity toward protonation.

Hybridization of Nitrogen

The hybridization state of a nitrogen atom plays a critical role in its basicity. When nitrogen is sp³-hybridized, as in many aliphatic amines, the lone pair is held in an orbital with less s-character, making it more available for bonding with a proton. In contrast, an sp²-hybridized nitrogen has greater s-character, meaning the electrons are held closer to the nucleus, which reduces their availability and thereby decreases the molecule’s basicity.

Aromaticity in Heterocycles

Aromaticity can influence the electronic characteristics of a molecule by delocalizing electrons within a cyclic, conjugated system. In aromatic heterocycles, even if the nitrogen’s lone pair is not directly involved in the aromatic sextet, the overall electron distribution and stabilization caused by aromaticity can lessen the propensity of that lone pair to engage in proton binding, thus contributing to reduced basicity.

Transcript

Please give Ace some feedback