An epoxide is a cyclic ether which contains a three atom ring that approximates an equilateral triangle. These are highly reactive when compared to other ethers. The fundamental structure of it contains two carbon atoms of a hydrocarbon attached to an oxygen atom. The structure can be chemically shown as
Economically Ethylene oxide is the most important epoxide and is created by oxidation of ethylene over a silver catalyst. It is used as a fumigant and to make ethylene glycol, antifreeze and other useful compounds.
Epoxide can be synthesized in many ways. Propylene oxide and Ethylene oxide are the two epoxides that are produced in a large scale, approximately 3 and 15 tonnes/year respectively.
- Heterogeneously Catalyzed oxidation of alkenes
When ethylene reacts with oxygen under a silver catalyst, epoxide is formed. According to stoichiometry, it can be chemically expressed as
7 H2C=CH2 + 6 O2 → 6 C2H4O + 2 CO2 + 2 H2O
- Homogeneously catalysed asymmetric epoxidation
Chiral epoxides can be made from prochiral alkenes. Lot of metal complexes act as active catalysts and the most important among them are vanadium, molybdenum and titanium.
- Nucleophilic epoxidation
Electron deficient olefins can be epoxidized using compounds such as peroxides. This reaction has two steps: firstly, nucleophilic conjugate is added to an oxygen atom to give a stabilized carbanion.
Epoxides are not common in nature. They are produced generally by oxygenation of alkenes.
Epoxides- Uses or applications
- Ethylene epoxide has many uses including generation of surfactants and detergents.
- Epoxy glues and structural materials are a result of epoxides reaction with amines.
- It is used as a stabilizer in materials like PVC. They are also used in manufacture of Epoxy resists that have low viscosity and without compromising strength and physical properties.
Epoxides are also used in things like insecticides, aerosols, resins and chemical intermediates.