Description
Ethylene oxide (C2H4O) is a kind of cyclic ether with important industrial applications. Although it is highly toxic and dangerous for household application and consumers to use, it can be used for the manufacture of many important industrial and commercialized products as well as some chemicals and intermediates. For example, it is very useful in the production of detergents, thickeners, solvents, plastics, and many kinds of organic chemicals such as ethylene glycol, ethanolamines, simple and complex glycols, polyglycol ethers, and other compounds. It is also a commonly sterilization methods used in the healthcare industry. In addition, it can be used as an accelerator of maturation of tobacco leaves and fungicide, as well as the main component of thermobaric weapons (fuel-air explosives). In industry, it is generally manufactured through direct oxidation of ethylene. In low doses, it can be used as a pesticide and a sterilizing agent owing to its effect of causing DNA damage. However, this property also make it a potential carcinogen.
ethylene oxide structure
Chemical Properties
Ethylene oxide is the simplest cyclic ether. It is a colorless gas or liquid and has a sweet, etheric odor. Ethylene oxide is a flammable, very reactive and explosive chemical substance. On decomposition, vapors of pure ethylene oxide mix with air or inert gases and become highly explosive. Ethylene oxide, is used in large scale as an intermediate in the production of monoethylene glycol, diethylene glycol, triethylene glycol, poly(ethylene) glycols, ethylene glycol ethers, ethanolamine, ethoxylation products of fatty alcohols, fatty amines, alkyl phenols, cellulose, and poly(propylene glycol). It is also used as a fumigant for food and cosmetics, and in hospital sterilization of surgical equipment and heat sensitive materials.
Occurrence
Reported found in Bantu beer.
Uses
Fumigant for foodstuffs and textiles; to sterilize surgical instruments; agricultural fungicide. In organic syntheses, especially in the production of ethylene glycol. Starting material for the manufacture of acrylonitrile and nonionic surfactants.
Uses
The major use of ethylene oxide in the United States (accounting for over 99% of production) is as an intermediate in the production of several industrial chemicals (ATSDR 1990, IARC 1994). The remainder is used in the gaseous form, either alone or combined with nitrogen, carbon dioxide, or dichlorofluoromethane as a sterilizing agent, disinfectant, fumigant, or insecticide. The largest use (about 60%) is to produce ethylene glycol (antifreeze). Other chemicals produced from ethylene oxide include non-ionic surfactants (used in industrial applications, detergents, and dishwashing formulations), glycol ethers, ethanolamines (used in soaps, detergents, and textile chemicals), diethylene glycol, triethylene glycol, polyethylene glycol, and urethane polyols. Although a relatively small percentage of ethylene oxide is used as a fumigant or sterilizing agent, these uses involve a variety of facilities, products, and materials, including hospital equipment, medical and dental clinics, research laboratories, foods, furs, clothing, furniture, books, paper, leather, cosmetics, drugs, railroad cars, beehives, and tobacco. Facilities that manufacture sterile disposable medical supplies and medical facilities, including hospitals, medical and dental clinics, and private medical and dental surgeries, account for about 95% of the ethylene oxide used as a fumigant or sterilant. In hospitals, ethylene oxide is used as a gaseous sterilant for heatsensitive medical items, surgical instruments, and other objects and fluids coming in contact with biological tissues. Before 1966, ethylene oxide was used as an intermediate in the production of acrylonitrile.
Uses
Ethylene oxide is widely used as a sterilizingagent; as a fumigant; as a propellant; in theproduction of explosives; in the manufactureof ethylene glycol, polyethylene oxide, gly-col ethers, crown ethers, ethanolamines, andother derivatives; and in organic synthesis.
Preparation
By catalytic oxidation of ethylene.
Production Methods
Ethylene oxide is currently produced by the direct oxidation
of ethylene with oxygen or air over a catalyst. Ethylene is
approximately 60% converted to the oxide at temperatures in
the range of 100–150℃. In the past, an indirect but more
general and more specific synthesis path consisted of adding
hypochlorous acid to olefins to form the chlorohydrins.
Subsequent treatment with strong bases results in dehydrochlorination
and the formation of the epoxide.
Definition
ChEBI: A saturated organic heteromonocyclic parent that is a three-membered heterocycle of two carbon atoms and one oxygen atom.
Aroma threshold values
Detection: 260 ppm; recognition: 500 ppm
Air & Water Reactions
Highly flammable. Flammable over a wide vapor-air concentration range. Must be diluted on the order of 24 to 1 with water to lose flammability. Soluble in water.
Reactivity Profile
Colorless gas at room temperature (b.p. 11°C), confirmed carcinogen. Highly flammable, severe explosion hazard when exposed to flame. The autoignition temperature may be as low as 140° C in presence of rust. Rapid compression of the vapor with air causes explosion. ETHYLENE OXIDE vapor may be initiated into explosive decomposition in absence of air [Hess, L. G., et al., Ind. Eng. Chem., 1950, 42, p. 1251]. Metal fittings containing magnesium, copper or silver should be avoided, since traces of acetylene in ETHYLENE OXIDE may produce metal acetylides capable of detonating the vapor [MCA SD-38, 1971]. Violent polymerization occurs on contact with strong bases (alkali hydroxides, ammonia) or acids, amines, metallic potassium, oxides (aluminum oxide, iron oxide, rust), covalent halides (aluminum chloride, ferric chloride, tin(IV) chloride) [Gupta, A. K., J. Soc. Chem. Ind., 1949, 68, p. 179]. Violent reaction with m-nitroaniline, magnesium perchlorate, mercaptans, thiols, triethylamine [Bretherick, 5th ed., 1995, p. 316]. ETHYLENE OXIDE and SO2 can react violently in pyridine solution with pressurization if ETHYLENE OXIDE is in excess (Nolan, 1983, Case History 51).
Hazard
Irritant to eyes and skin. Confirmed carcinogen. Highly flammable, dangerous fire and
explosion risk, flammable limits in air 3–100%.
Health Hazard
Ethylene oxide is a severe irritant, as well asa toxic and carcinogenic compound. Inhala-tion can cause severe irritation in the eyes,respiratory tract, and skin. In humans, thedelayed symptoms may be nausea, vomit-ing, headache, dyspnea, pulmonary edema,weakness, and drowsiness. Exposure to highconcentrations can cause central nervous sys-tem depression.
Contact with an aqueous solution of ethy-lene oxide on skin can produce severe burnsafter a delay period of a few hours. It maybe absorbed by plastic, leather, and rubbermaterials if not handled properly, and cancause severe skin irritation.
Exposure of test animals to a high con-centration of ethylene oxide resulted inthe watering of eyes, nasal discharge, and labored breathing. The toxic effects observedafter a few days were vomiting, diarrhea,pulmonary edema, dyspnea, and convulsion,followed by death.
Ethylene oxide is a teratogen, causingbirth defects. Laboratory tests on animalsindicated that exposure could cause fetaldeaths, specific developmental abnormalities,and paternal effects related to testes andsperm ducts.
Ethylene oxide showed positive carcino-genicity in test animals. Inhalation, ingestion,and subcutaneous application over a periodof time developed tumors of all kinds in ratsand mice. It caused brain, liver, gastroin-testinal, and blood cancers in test subjects.Ethylene oxide and 1,2- propylene oxideeach mixed with salad oil induced squamous-cell carcinomas of the forestomach whenadministered intra-gastrically by gavage tofemale Sprague-Dawley rats (Dunkelberg1982). The study was carried out for a periodof 3 years and the first tumor occurred inthe 79th week for both compounds. Nei-ther compound, however, induced tumors atsites away from the point of administration.Experimental studies on rodents indicatedthat subacute exposures to ethylene oxideat a concentration of 1 ppm caused DNAdamage producing the DNA adduct, 7-(2-hydroxyethyl)guanine (Thier and Bolt 2000).Although the evidence of its carcinogenicityin humans is inadequate, it is suspected to becancer causing to humans.
Ethylene oxide is a mutagen in animalsand humans. It causes chromosomal aber-rations (Thiess et al. 1981), errors in DNAsynthesis (Cumming et al. 1981), and alky-lation of hemoglobin (Calleman et al. 1978).
Repeated brief exposures to ethylene oxideat 800 and 1200 ppm caused fetal toxicityindicated by reduced fetal weight in rats(Saillenfait et al. 1996).
Flammability and Explosibility
Ethylene oxide is an extremely flammable substance (NFPA rating = 4). Ethylene oxide vapor may be ignited by hot surfaces such as hot plates and static electricity discharges, and since the vapor is heavier than air, it may travel a considerable distance to an ignition source and flash back. Ethylene oxide vapor forms explosive mixtures with air at concentrations of 3 to 100% (by volume). Carbon dioxide or dry chemical extinguishers should be used for ethylene oxide fires. Ethylene oxide may explode when heated in a closed vessel.
Agricultural Uses
Fungicide and fumigant: Ethylene oxide is used as a fumigant for spices, seasonings,
and foodstuffs and as an agricultural fungicide.
When used directly in the gaseous form or in nonexplosive
gaseous mixtures with nitrogen or carbon dioxide, ethylene
oxide can act as a disinfectant, fumigant, sterilizing
agent, and insecticide. It is a man-made chemical used as
an intermediate in organic synthesis for ethylene glycol,
polyglycols, glycol ethers, esters, ethanolamines, acrylonitrile,
plastics, and surface-active agents. It is also used
as a fumigant for textiles and for sterilization, especially
for surgical instruments. It is used in drug synthesis and
as a pesticide intermediate. Not approved for use in EU
countries. Actively registered in the U.S.
Trade name
AMPROLENE®; ANPROLENE®;
ANPROLINE®; BIODAC®; MERPOL®; OXYFUME®;
OXYFUME 12®; T-GAS®; STERILIZING GAS
ETHYLENE OXIDE 100%®
Contact allergens
Ethylene oxide is a very strong irritant widely used in
the chemical industry, and as a sterilizer of medical
supplies, pharmaceutical products, and food. It can
produce immediate (urticaria, asthma, anaphylaxis) or
delayed reactions (irritant rather than allergic contact
dermatitis). For example, residues in masks or dressings
can produce irritant contact dermatitis.In delayed
contact allergy, it seems that cross-reaction can be
observed to epichlorhydrin or epoxypropane
Materials Uses
Steel and stainless steel are suitable materials
for equipment and piping in ethylene oxide
service. Dangerous runaway reactions can result
from contact with copper, silver, magnesium and their alloys; mercury and its salts; oxidizers
of all types; alkalis and acids; alcohols; mercaptans;
and alkali metals. Ethylene oxide will
polymerize violently if contaminated with aqueous
alkalis, amines, mineral acids, metal chlorides,
or metal oxides.
Safety Profile
Confirmed human
carcinogen with experimental carcinogenic,
tumorigenic, neoplastigenic, and teratogenic
data. Poison by ingestion, intraperitoneal,
subcutaneous, and intravenous routes.
Moderately toxic by inhalation. Human
systemic effects by inhalation: convulsions,
nausea, vomiting, olfactory and pulmonary
changes. Experimental reproductive effects.
Mutation data reported. A skin and eye
irritant. An irritant to mucous membranes of
respiratory tract. High concentrations can
cause pulmonary edema.
Highly flammable liquid or gas. Severe
explosion hazard when exposed to flame.
To fight fire, use alcohol foam, CO2, dry
chemical. Violent polymerization occurs on
contact with ammonia, alkali hydroxides,
amines, metalllc potassium, acids, covalent
halides (e.g., aluminum chloride, iron(Ⅲ)
chloride, tin(rv> chloride, aluminum oxide,
iron oxide, rust). Explosive reaction with
glycerol at 200℃. Rapid compression of the
vapor with air causes explosions. Incompatible with bases, alcohols, air, m-nitroanlline,
trimethyl amine, copper, iron chlorides, iron
oxides, magnesium perchlorate, mercaptans,
potassium, tin chlorides, contaminants,
alkane thols, bromoethane. When heated to decomposition it emits acrid smoke and
irritating fumes.
Potential Exposure
Ethylene oxide is a man-made chemical used in the production of glycols (ethylene glycol, polyglycols, glycol ethers, esters), nontonic surface-active
agent; ethanolamines, acrylonitrile, plastics. It is also used
as a fumigant for foodstuffs and textiles; an agricultural
fungicide; and for sterilization, especially for surgical
instruments. It is used in drug synthesis and as a pesticide
intermediate
Physiological effects
Ethylene oxide is a toxic liquid and gas. Contact
of the eyes with liquid ethylene oxide can cause
severe irritation and corneal injury. Eye contact
with the vapor can cause moderate irritation.
Skin contact with the liquid or vapor or water
solutions can cause severe delayed chemical
bums. Inhalation of vapor will cause irritation
of the respiratory tract, which may result in
headache, nausea, and vomiting. All cases of
inhalation or contact with ethylene oxide liquid
or vapor must receive immediate first aid action
followed by medical attention.
First aid
If ethylene oxide gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit. Iffrostbite has occurred, seek medical attention immediately;do NOT rub the affected areas or flush them with water. Inorder to prevent further tissue damage, do NOT attempt toremove frozen clothing from frostbitten areas. If frostbitehas NOT occurred, immediately and thoroughly wash contaminated skin with soap and water. Medical observation isrecommended for 24- 48 h after breathing overexposure, aspulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consideradministering a corticosteroid spray.
Carcinogenicity
Ethylene oxide is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans, including epidemiological studies and studies on mechanisms of carcinogenesis. Ethylene oxide was first listed in the Fourth Annual Report on Carcinogens in 1985 as reasonably anticipated to be a human carcinogen based on limited evidence of carcinogenicity from studies in humansand sufficient evidence of carcinogenicity from studies in experimental animals. The listing was revised to known to be a human carcinogen in the Ninth Report on Carcinogens in 2000.
An increased risk of cancer has been demonstrated in epidemiological studies of workers using ethylene oxide as a sterilant for medical devices and spices and in chemical synthesis and production.Evidence for a common mechanism of carcinogenesis in humans and experimental animals comes from studies that have found similar genetic damage in cells of animals and workers exposed to ethylene oxide. The DNA-damaging activity of ethylene oxide explains its effectiveness as a sterilant, and this same property accounts for its carcinogenic risk to humans.
Environmental Fate
Ethylene oxide released to the environment partitions primarily
to the atmosphere due to its high volatility (vapor pressure
146 kPa at 20℃). Although the high water solubility of
ethylene oxide suggests it can be extracted from air by rainfall, its
rapid volatilization from water (half-life of 1 h) argues against
this process being a significant factor in its environmental fate.
In the atmosphere, ethylene oxide reacts with hydroxyl radicals
resulting in a half-life of 2–5 months. In freshwater, ethylene
oxide is hydrolyzed to ethylene glycol (half-life ～ 1 week); in
salt water, it is hydrolyzed to ethylene glycol and ethylene
chlorohydrin (half-life ～2 weeks). In unacclimated aqueous
media, ethylene oxide is also subject to biodegradation with
estimated half-lives of 1–6 months (aerobic) and 4–24 months
(anaerobic). However, in the presence of activated sludge,
ethylene oxide is readily biodegradable. Due to its high volatility
and water solubility, ethylene oxide is not expected to persist in
soil or sediments. The low log Kow (-0.30) for ethylene oxide
indicates little potential for bioaccumulation.
storage
work with ethylene oxide should be conducted in a fume hood to prevent exposure by inhalation, and appropriate impermeable gloves and splash goggles should be worn at all times to prevent skin and eye contact. Ethylene oxide should be used only in areas free of ignition sources and should be stored in the cold in tightly sealed containers placed within a secondary container.
Shipping
UN1040 Ethylene oxide or Ethylene oxide with
nitrogen up to a total pressure of 1 MPa (10 bar) at 50℃,
Hazard Class: 2.3; Labels: 2.3-Poisonous gas, 2.1-
Flammable gas, Inhalation Hazard Zone D. Cylinders must
be transported in a secure upright position, in a wellventilated truck. Protect cylinder and labels from physical
damage. The owner of the compressed gas cylinder is the
only entity allowed by federal law (49CFR) to transport
and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express
written permission of the owner
Purification Methods
Dry oxirane with CaSO4, then distil it from crushed NaOH. It has also been purified by passage, as a gas, through towers containing solid NaOH. [Beilstein 17/1 V 3.]
Toxicity evaluation
The mechanisms of toxicity are not yet understood; however, it
is likely that, in general, the toxic effects of ethylene oxide are
due to its ability to react with cellular molecules, altering
function. Attempts to link the carcinogenicity of ethylene oxide
noted in experimental animals to ethylene oxide-induced DNA
adducts, including the major adduct formed (N7-hydroxyethyl
guanine), have been unsuccessful. Research on the mode of
action for ethylene oxide-induced carcinogenicity includes
work focused on the potential role of glutathione depletion
and the resulting oxidative stress, events that can occur after
exposure to high levels of ethylene oxide.
Incompatibilities
May form explosive mixture with air.
Chemically unstable. Dangerously reactive; may rearrange
chemically and/or polymerize violently with evolution of
heat; when in contact with highly active catalytic surfaces,
such as anhydrous chlorides of iron, tin and aluminum;
pure oxides of iron and aluminum; and alkali metal hydroxides. Even small amounts of strong acids; alkalis, or oxidizers can cause a reaction. Avoid contact with copper.
Protect container from physical damage, sun and heat.
Attacks some plastics, rubber or coatings.
Toxics Screening Level
The Initial Risk Screening Level (IRSL) for Ethylene oxide (EtO) is 0.0002 μg/m3, with annual averaging time (AT).
Waste Disposal
Return refillable compressed
gas cylinders to supplier. Concentrated waste containing no
peroxides-discharge liquid at a controlled rate near a pilot
flame. Concentrated waste containing peroxides-perforation
of a container of the waste from a safe distance followed
by open burning
Precautions
Ethylene oxide is dangerously explosive under fi re condition; it is flammable over an extremely large range of concentrations in air and burns in the absence of oxygen.
References
https://en.wikipedia.org/wiki/Ethylene_oxide
https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/ethylene-oxide
GRADES AVAILABLE
Ethylene oxide is sold only in grades of 99.7
percent or higher purity.
Ranges in specification values indicate a difference
in the limits given by different producers
[2].
