Oxiranyl

Oxiranyl is the name given to the three-membered cyclic ether substituent or radical derived from oxirane (ethylene oxide). Structurally, an oxiranyl unit consists of a triangular ring with two carbon atoms and one oxygen atom; the small ring size produces substantial angle and torsional strain, which strongly influences its chemical behavior.

Because of this ring strain, oxiranyl-containing compounds (commonly called epoxides when the ring is intact) are relatively reactive. The strained C–O–C ring is susceptible to ring-opening reactions under a variety of conditions, including nucleophilic attack, acid or base catalysis, and radical processes. These ring-opening pathways are exploited in organic synthesis to form vicinal diols, alcohols, ethers and other functionalized products, and in polymer chemistry for the production of polyethers and crosslinked epoxy resins.

In mechanistic and synthetic contexts, the term oxiranyl may refer specifically to a radical or substituent derived from oxirane (formally C2H3O· or C2H3O–), which can appear as a transient intermediate in oxidation, combustion, or rearrangement reactions. As a substituent name in systematic nomenclature, oxiranyl denotes an attached oxirane ring; the prefix epoxy is also widely used in common nomenclature.

Many epoxides and oxiranyl-containing materials are chemically reactive and can be irritants or sensitizers, so they are handled with appropriate safety precautions in laboratory and industrial settings.