Oxiran

Oxiran, commonly called oxirane or ethylene oxide, is the smallest epoxide, a cyclic ether with a three-member ring containing two carbon atoms and one oxygen. Its molecular formula is C2H4O. The ring is highly strained, which makes the molecule especially reactive in ring-opening reactions with nucleophiles or acids.

At room temperature, oxirane is a colorless gas with a boiling point around −12 to −13 °C. It is highly flammable and mixes with many organic solvents. It hydrolizes readily in water to give ethylene glycol, and it is soluble in common solvents. The compound is toxic by inhalation and irritation, and proper handling requires controlled environments and ventilation.

Industrial production occurs mainly by two routes: the chlorohydrin process, in which ethylene reacts with chlorine to form chlorohydrins that are treated with base to yield oxirane; and direct oxidation of ethylene with oxygen over silver catalysts. Each route is optimized for safety, efficiency, and emissions control.

As a reactive epoxide, oxirane is a key building block in the chemical industry. It serves as the precursor to ethylene glycol and related glycols, surfactants, and solvents. It is also a foundational monomer for epoxy resins, polymers formed by opening the oxirane ring and linking with hardeners to create durable coatings and composites.

Safety and regulation: oxirane is classified as hazardous, flammable, and potentially carcinogenic. Exposure limits are established in many jurisdictions, and storage and handling require appropriate containment, inhibitors to control polymerization, and strict process controls to minimize environmental release.