Pyrrole is a
heterocyclic aromatic organic compound, a five-membered ring with the
formula C4H4NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g.,
N-methylpyrrole, C
4H
4NCH
3.
Porphobilinogen, a trisubstituted pyrrole, is the biosynthetic precursor to many natural products such as
heme.