Allene

Allene, also known as propadiene, is the simplest member of the allene family of hydrocarbons. It has the molecular formula C3H4 and a structure of H2C=C=CH2, with a central carbon atom double-bonded to two terminal carbons. The molecule contains two cumulated π bonds, which forces the substituents on the two ends to lie in perpendicular planes. This geometry gives allenes distinctive reactivity and, when the ends carry different substituents, can create axial chirality.

Allene is used as a synthetic building block in organic chemistry. It participates in a variety of reactions, including cycloadditions, cross-couplings, and various transformations catalyzed by transition metals. Substituted allenes serve as versatile motifs for the construction of complex molecules, natural products, and advanced materials.

In addition to its role in laboratories, the term Allene is also used as a given name for people and can refer to other uses such as places or organizations, depending on context. The allene motif continues to be studied in chemistry for its unusual electronic structure and for developing new catalytic methods and synthetic strategies.