ETHYLENE OXIDE

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

Description

Ethylene oxide is the smallest of the oxirane family of molecules. It is a sweet-smelling, colorless gas that has many uses; but its high reactivity presents many hazards.
Back in 1859, A. Wurtz treated ethylene chlorohydrin with potassium hydroxide to make ethylene oxide and potassium chloride. In 1914, BASF built the first ethylene oxide plant, which used the chlorohydrin method, but with calcium hydroxide instead of KOH. This process was eventually superseded by the direct oxidation of ethylene, which is used exclusively today.
The uses of ethylene oxide are numerous. By far, its primary use is as a raw material for the industrial manufacture of ethylene glycol and its oligomers, glycol ethers, and ethanolamines. Minor, but important, direct applications include a fumigant for foods and textiles; an agricultural fungicide and insecticide; and a sterilant for medical equipment.
As shown in the hazard information table, many of ethylene oxide’s uses also make it extremely dangerous. Its carcinogenicity is of special concern. The US Environmental Protection Agency is under a court order to decide by March 13, 2020, whether to tighten the 2006 standards set for air pollution by ethylene oxide and other organic chemicals.
There is broad disagreement between environmental and industrial advocates as to the safe concentration of ethylene oxide in air. Proposals range from 0.1 ppt to 4 ppb—a factor of 40,000. Both sides are beginning to pressure EPA to see things their way.

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.

The Uses of ETHYLENE OXIDE

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.

The Uses of ETHYLENE OXIDE

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.

The Uses of ETHYLENE OXIDE

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.

Definition

ChEBI: A saturated organic heteromonocyclic parent that is a three-membered heterocycle of two carbon atoms and one oxygen atom.

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.

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.

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].