Pirrol

Pirrol is typically a misspelling of pyrrole, a heterocyclic organic compound that features a five-membered ring containing four carbon atoms and one nitrogen atom. In pyrrole, the nitrogen bears a hydrogen (NH) and is part of an aromatic system; the ring contains six π electrons, making it aromatic. The molecular formula is C4H5N. The nitrogen lone pair is delocalized in the ring, which renders pyrrole far less basic than many amines.

Pyrrole is generally a colorless to pale yellow liquid with a characteristic odor and is notable for its tendency to polymerize. It is moderately reactive toward electrophilic substitution at the 2- and 3-positions of the ring, and N-substitution yields N-substituted pyrroles. The ring’s electron-rich nature underpins its use as a building block in organic synthesis and in materials science.

Applications and occurrence: Pyrrole is a fundamental unit in many natural products, most famously as a building block of porphyrins, which constitute heme and chlorophyll. It is also used as a monomer in conducting polymers such as polypyrrole and serves as a precursor for pharmaceuticals and dyes.

Preparation and safety: Pyrrole can be prepared by several methods, including the Paal–Knorr synthesis from 1,4-dicarbonyl compounds using ammonia or primary amines, as well as other condensation routes. It is flammable and can be toxic by inhalation; handling requires appropriate ventilation and protective equipment. Note: pirrol is commonly a misspelling of pyrrole.