The compound shown is an aromatic heterocycle that is an extremely weak base (pKaH about -4). The reason is that

Athe nitrogen lone pair is part of the aromatic pi sextet
Bthe nitrogen atom is sp3 hybridised
Cthe five-membered ring is strained
Dthe N-H forms strong hydrogen bonds with water

Answer: A

In pyrrole the nitrogen lone pair is part of the six pi electrons of the aromatic sextet. Protonation on nitrogen would destroy aromaticity, so pyrrole is protonated (weakly) on carbon only in strong acid. The nitrogen is sp2, not sp3, and no ring strain or hydrogen bonding explains the low basicity.

Practice General Organic Chemistry II: Acids and Bases More on Basicity order among drawn amines and heterocycles

Previous questionNext question

More questions on Basicity order among drawn amines and heterocycles

Four nitrogen compounds are shown beside the options (the drawn compound is ammonia, pKaH 9.3, for reference). Which structure is the strong... NEET level
Four anilines are shown beside the options (the drawn compound is aniline). Which structure is the weakest base? NEET level
Four nitrogen compounds are shown beside the options (the drawn compound is pyrimidine, for reference). Which structure is the strongest bas... NEET level
Four heterocycles are shown beside the options (the drawn compound is thiazole, for reference). Which structure is the strongest base? JEE Main level
Four compounds are shown beside the options (the drawn compound is urea, for reference). Which structure is the strongest base? JEE Main level
Four amines are shown beside the options (the drawn compound is aniline, pKaH 4.6). Select ALL the structures that are stronger bases than t... JEE Main level