Oksiranirenkaan

Oksiranirenkaan, in chemistry often called the oxirane ring or epoxide ring, refers to a three-membered heterocycle that contains two carbon atoms and one oxygen atom. The simplest member is oxirane, also known as ethylene oxide (C2H4O). The ring is highly strained because the internal bond angles are about 60 degrees, which drives a high level of reactivity, especially toward ring-opening reactions.

Structure and properties: The oxirane ring is a small, highly reactive functional group found in many organic compounds. Its strain makes epoxides susceptible to nucleophilic attack and to various rearrangements under different conditions. The ring can be substituted at either of the carbon atoms, which influences regioselectivity in reactions.

Reactivity and reactions: Epoxides commonly undergo ring-opening by nucleophiles. Under basic or neutral conditions, nucleophiles prefer attacking the less substituted carbon, leading to regioselective products. In acidic media, protonation of the ring oxygen increases electrophilicity, and nucleophiles can attack the more substituted carbon. Common nucleophiles include halides, water, alcohols, and amines. Epoxides can also participate in rearrangements or be converted to diols, glycols, or other derivatives through subsequent functional-group transformations.

Production and occurrence: Ethylene oxide is produced industrially by oxidation of ethylene with oxygen over catalysts. Laboratory methods include peracid epoxidation, such as using m-chloroperbenzoic acid (mCPBA). Epoxide groups occur in a wide range of natural products and synthetic intermediates.

Applications and safety: Epoxides are versatile intermediates in organic synthesis and are key components in epoxy resins used in polymers. They are reactive and can be irritants or toxic; proper handling is required to manage flammability and exothermic ring-opening reactions.