Ethylene oxide is a chemically-physiological compound, a colourless, flammable gas at room temperature, which is produced industrially by the catalytic oxidation of ethylene. Ethylene is a normal constituent of the human body.

The name defines the structure of the molecule:

• Ethylene is a chemical compound with the formula C2H4, a flammable gas that is commonly used in the production of various chemicals, plastics and solvents. Ethylene is a hydrocarbon and belongs to the alkenes family.
• Oxide refers to a compound that contains an oxygen atom bound to another element. In the case of ethylene oxide, it consists of an oxygen atom bound to one of the carbon atoms in the ethylene molecule.

The synthesis process takes place in several stages:

• Preparation of ethylene. Ethylene is a hydrocarbon that can be obtained from natural gas or petroleum. It is industrially produced by steam cracking, a process in which hydrocarbons are heated to break their chemical bonds and form smaller molecules.
• Oxidation. Ethylene is then oxidized to form ethylene oxide. This is done using a silver catalyst and air or oxygen at high temperatures and high pressure.

What it is used for and where it is used

Ethylene Oxide is a key raw material used in the manufacture of a wide range of chemicals, including antifreeze, textiles, plastics, detergents and resins. It's also used for sterilization of medical equipment and supplies. 

It has antimicrobial, antibacterial and antifungal properties that are used by various industries to sterilise with a relatively long procedure (three to 24 hours). According to the Clean Air Act (United States Environmental Protection Agency) of 1990, ethylene oxide is one of 188 recognised hazardous air pollutants and the use of this gas is strictly regulated as it is considered a human carcinogen. 

Medicine and pharmaceuticals

Ethylene oxide is an intermediate chemical compound in the production of ethylene glycols, glycol ethers, polyethylene glycols, polyethylenes, ethanolamines, ethoxylates, which are used by the plastics industry, the packaging industry and for various types of fibres (glass. polyester). 

It is used for the sterilisation of medical devices that could be damaged if sterilised with steam because they contain electronics or plastic. 

Food

Ethylene oxide is a sterilising smoking agent for spices, dried fruits, dried pulses and others and is also used to improve the ripening of fruits such as tomatoes and bananas.

Cosmetics

It is a restricted ingredient as II/182  a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Carcinogenic 1B Mutagenic 1/B.

Other uses

Ethylene oxide is a losteriliser and carbon dioxide is used as a propellant gas which has replaced Freon or dichlorodifluoromethane (CFC-12) as an environmentally harmful, class I ozone-depleting substance.

It is used in the processing of: paper, leather, coins, scrap metal, bioengineering, laboratories etc.

Safety

Numerous studies have been conducted on the safety of ethylene oxide, and as early as 2012, the IARC (International Agency for Research on Cancer) assessed it as carcinogenic to humans.

In December 2018, the US Environmental Protection Agency (EPA) published an update on the safety assessment, warning that exposure to this chemical can cause, with short-term exposure, depression of the central nervous system and irritation of the eyes and mucous membranes and, with long-term exposure, irritation of the eyes, skin, nose, throat and lungs and damage to the brain and nervous system. The EPA concludes that exposure to ethylene oxide increases the risk of lymphoid cancer and, for females, breast cancer (1).

Ethylene oxide studies

Ethylene Oxide data sheet

Boiling Point	10.7°
Melting Point	−111°C
Flash Point	-17.7ºC
Density	0.882 g/mL at 25 °C(lit.)
LogP	0.01660
Index of Refraction	n20/D 1.3597(lit.)
Safety

• Molecular Formula  C₂H₄O
• Molecular Weight     44.05
• Exact Mass    44.02620
• CAS  75-21-8
• UNII    JJH7GNN18P
• EC Number   200-849-9
• DSSTox Substance ID   DTXSID0020600
• IUPAC  oxirane
• InChI=1S/C2H4O/c1-2-3-1/h1-2H2 
• InChl Key      IAYPIBMASNFSPL-UHFFFAOYSA-N
• SMILES   C1CO1
• MDL number  MFCD00014482
• PubChem Substance ID    329747833
• ChEBI  27561
• ICSC    0155
• Beilstein       102378
• RTECS   KX2450000
• UN   1040
• NCI  C29821
• NACRES  NA22

Synonyms:

• oxirane
• Epoxyethane

References_______________________________________________________________________

(1) ethylene-oxide.pdf (epa.gov)