epoksidid

Epoxides, also known as oxiranes, are a class of organic compounds featuring a three-membered ring consisting of two carbon atoms and one oxygen atom. The ring is highly strained, which gives epoxides their characteristic reactivity. The simplest member is oxirane, commonly called ethylene oxide.

Synthesis of epoxides is typically accomplished by epoxidizing alkenes with peracids (for example, m-chloroperbenzoic acid) or by catalytic systems that generate an oxidizing species in situ. Other routes include dehydration of halohydrins or conversion of vicinal diols. Epoxidation is often stereospecific, preserving the alkene’s stereochemistry.

Epoxides are highly reactive toward nucleophiles and can undergo ring-opening to give beta-hydroxy compounds. Under basic conditions, nucleophiles attack the less substituted carbon; under acidic conditions, attack tends to happen at the more substituted carbon. This reactivity makes epoxides versatile intermediates in organic synthesis. They are also central to the production of polymers, solvents, and specialty chemicals. Epoxide resins, formed from diepoxides and curing agents such as amines or acid anhydrides, produce crosslinked networks used in coatings, adhesives, and composites. A widely used epoxy resin precursor is diglycidyl ether of bisphenol A (DGEBA).

Safety and occurrence: Epoxides can be irritants and some are toxic or carcinogenic; many are volatile and reactive, requiring careful handling under ventilation and with appropriate stabilizers to prevent runaway polymerization. Epoxides also occur as natural metabolites in some organisms and as intermediates in various biosynthetic pathways.