Ethylene oxide

C₂H₄OMolar mass44.052g·mol Appearance Colorless gas OdorLike diethyl ether Density0.8821g·cm Melting point−112.46 °C (−170.43 °F; 160.69 K) Boiling point10.4 °C (50.7 °F; 283.5 K)

Solubility in water

Miscible Vapor pressure1.46atm (20°C)

Magnetic susceptibility (χ)

−30.5·10cm/mol

Refractive index (n_D)

1.3597 (589nm)

Dipole moment

1.94D Thermochemistry

Heat capacity(C)

47.9J·mol·K

Std molar
entropy(S₂₉₈)

242.5J·mol·K

Std enthalpy of
formation(Δ_fH₂₉₈)

−52.6kJ·mol

Gibbs free energy(Δ_fG)

−13.0kJ·mol Hazards Occupational safety and health (OHS/OSH):

Main hazards

Carcinogen
Extremely flammable GHS labelling:

Pictograms

Hazard statements

H220, H230, H301, H314, H331, H335, H336, H340, H350, H360FD, H372

Precautionary statements

P202, P210, P260, P280, P301+P310+P330, P303+P361+P353, P305+P351+P338+P310, P410+P403NFPA 704 (fire diamond)

3

4

3

Flash point−20 °C (−4 °F; 253 K)

Autoignition
temperature

429 °C (804 °F; 702 K) Explosive limits3 to 100% Lethal dose or concentration (LD, LC):

LC₅₀ (median concentration)

836ppm (mouse, 4hr)
4000ppm (rat, 4hr)
800ppm (rat, 4hr)
819ppm (guinea pig, 4hr)
1460ppm (rat, 4hr)
835ppm (mouse, 4hr)
960ppm (dog, 4hr) NIOSH (US health exposure limits):

PEL (Permissible)

TWA 1ppm 5ppm [15-minute excursion]

REL (Recommended)

Ca TWA <0.1ppm (0.18mg/m) C 5ppm (9mg/m) [10-min/day]

IDLH (Immediate danger)

Ca [800ppm] Safety data sheet (SDS) ICSC 0155Related compounds

Related heterocycles

Aziridine,
thiirane,
borirane

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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Ethylene oxide is an organic compound with the formulaC₂H₄O. It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sweet odor. Because it is a strained ring, ethylene oxide easily participates in a number of addition reactions that result in ring-opening. Ethylene oxide is isomeric with acetaldehyde and with vinyl alcohol. Ethylene oxide is industrially produced by oxidation of ethylene in the presence of a silver catalyst.

The reactivity that is responsible for many of ethylene oxide's hazards also makes it useful. Although too dangerous for direct household use and generally unfamiliar to consumers, ethylene oxide is used for making many consumer products as well as non-consumer chemicals and intermediates. These products include detergents, thickeners, solvents, plastics, and various organic chemicals such as ethylene glycol, ethanolamines, simple and complex glycols, polyglycol ethers, and other compounds. Although it is a vital raw material with diverse applications, including the manufacture of products like polysorbate 20 and polyethylene glycol (PEG) that are often more effective and less toxic than alternative materials, ethylene oxide itself is a very hazardous substance. At room temperature it is a very flammable, carcinogenic, mutagenic, irritating; and anaesthetic gas.

Ethylene oxide is a surface disinfectant that is widely used in hospitals and the medical equipment industry to replace steam in the sterilization of heat-sensitive tools and equipment, such as disposable plastic syringes. It is so flammable and extremely explosive that it is used as a main component of thermobaric weapons; therefore, it is commonly handled and shipped as a refrigerated liquid to control its hazardous nature.