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Ethylene oxide

Ethylene oxide
IUPAC name epoxyethane
Other names ethylene oxide, dimethylene oxide, oxirane, oxacyclopropane
CAS number 75-21-8
PubChem 6354
EINECS number 200-849-9
KEGG C06548
MeSH Ethylene+Oxide
ChEBI 27561
RTECS number KX2450000
InChI InChI=1/C2H4O/c1-2-3-1/h1-2H2
Molecular formula C2H4O
Molar mass 44.05 g mol−1
Appearance colorless gas
Density 0.882
Melting point

−111.3 °C

Boiling point

10.7 °C

Solubility in water miscible
Std enthalpy of
−52.6 kJ mol−1
Standard molar
243 J mol−1 K−1
Flash point −20 °C
Explosive limits 3 to 100%
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

The chemical compound ethylene oxide is an important industrial chemical used as an intermediate in the production of ethylene glycol and other chemicals, and as a sterilant for foods and medical supplies. It is a colorless flammable gas or refrigerated liquid with a faintly sweet odor. It is the simplest example of an epoxide.

Its IUPAC name is epoxyethane. Other names for it include oxirane and dimethylene oxide.



Ethylene oxide was first prepared in 1859 by the French chemist Charles-Adolphe Wurtz,[1] who prepared it by treating 2-chloroethanol with a base. It achieved industrial importance during World War I as a precursor to both the coolant ethylene glycol and the chemical weapon mustard gas. In 1931, Theodore Lefort, another French chemist, discovered a means to prepare ethylene oxide directly from ethylene and oxygen, using silver as a catalyst. Since 1940, almost all ethylene oxide produced industrially has been made using this method.[2]


Industrially, ethylene oxide is produced when ethylene (CH2=CH2) and oxygen (O2) react on a silver catalyst at 200–300 °C showing large Ag nanoparticles supported on Alumina. Typically, chemical modifiers such as chlorine are also included. Pressures used are in the region of 1-2MPa. The chemical equation for this reaction is:

CH2=CH2 + ½ O2 → C2H4O

The typical yield for this reaction under industrial conditions is 70-80%. In the reaction scheme above, an intermediate (oxametallacycle) is formed. Two different reaction pathways can then occur.

Ethylene oxide formation:

CH2=CH2 + O → C2H4O

Acetaldehyde formation:

CH2=CH2 + O → CH3CHO

The latter pathway is the first step in complete combustion, leading to carbon dioxide and water:

CH3CHO +5/2 O2 → 2CO2 + 2H2O

Ethylene oxide can be conveniently produced in the laboratory by the action of an alkali hydroxide on ethylene chlorohydrin.[3]

CH2OH−CH2Cl + OH → C2H4O + Cl + H2O

with ethylene chlorohydrin being prepared easily by the action of hypochlorous acid on ethylene.

Several methods to produce ethylene oxide more selectively have been proposed, but none have achieved industrial importance.[citation needed]


Ethylene oxide gas kills bacteria (and their endospores), mold, and fungi, and can therefore be used to sterilize substances that would be damaged by sterilizing techniques such as pasteurization that rely on heat. Ethylene oxide sterilization for the preservation of spices was patented in 1938 by the American chemist Lloyd Hall, and it is still used in that role. Additionally, ethylene oxide is widely used to sterilize medical supplies such as bandages, sutures, and surgical implements. The overwhelming majority of medical items are sterilized with ethylene oxide. Preferred methods have been the traditional chamber sterilization method, where a chamber is flooded with a mix of ethylene oxide and other gases which are later aerated, and the more recent gas diffusion method developed in 1967 which relies on a bag that wraps the elements to be sterilized and acts a a mini-chamber in order to minimize gas consumption and make the process economically feasible for small loads. Other names for this alternative method for small loads are: Anprolene method, bag sterilization method or micro-dose sterilization method.

Most ethylene oxide, however, is used as an intermediate in the production of other chemicals. The major use of ethylene oxide is in the production of ethylene glycol. The primary end use for ethylene glycol is in the production of polyester polymers. Ethylene glycol is more commonly known for its use as an automotive coolant and antifreeze.

Because of its high flammability and wide explosive concentration range in air, ethylene oxide is sometimes used as the fuel component of a fuel-air explosive.


Most reactions are ring openings by nucleophiles.

In industry, epoxyethane is reacted with water in the presence of a sulfuric acid catalyst. A tenfold molar excess of water is used to obtain ethylene glycol:



n(CH2CH2O) + H2O → HO(CH2CH2O)nH





Health effects






See also


  1. ^ Wurtz, A. (1859). "". Compt. rend. 48: 101-104.
  2. ^ P. P. McClellan (1950). "Manufacture and Uses of Ethylene Oxide and Ethylene Glycol". Ind. Eng. Chem. 42: 2402 - 2407. doi:10.1021/ie50492a013.
  3. ^ Streitwiser, Andrew; Heathcock, Clayton H. (1976). Introduction to Organic Chemistry. Macmillan. ISBN 0-02-418010-6. 
  4. ^
  5. ^
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ethylene_oxide". A list of authors is available in Wikipedia.