CHEMICAL DATA NOTEBOOK SERIES #59: ETHYL ETHER
HAZARDOUS MATERIALS
Ethyl ether is a flammable, anesthetic, irritating, volatile, clear, colorless liquid with a “sweet,” pungent, characteristic odor. Its major uses are as an industrial solvent and extractant. It also is used in organic synthesis, in the manufacture of gun powder, as a refrigerant, in diesel fuels, and as a gasoline engine primer. Originally used universally as an anesthetic, it now has only limited use for that purpose.
PROPERTIES
Ethyl ether has a flash point of — 49°F, an ignition temperature of 320°F, and a flammable range of 1.8 to 36.5 percent in air. It has a specific gravity of 0.715, a molecular weight of 74, and a vapor density of 2.55. Its boiling point is 94.1 °F, its freezing point is — 177.3°F, and it is moderately soluble in water. Its molecular formula is C2H5OC2H5 (may be written also as C|HI0O or CHjCH2C)CH CH ⅜)
HAZARDS
Ethyl ether is extremely volatile, which means that it will evaporate very quickly at ambient temperatures, producing very large amounts of dangerous vapors. Those vapors, being 2.55 times heavier than air, will “hang together” for a long time. The degree and speed of dispersion of the vapors in air depend entirely on the strength of the wind.
The major hazard of ethyl ether is its flammability. Its extremely low flash point of — 49°F means that it could generate enough vapors to produce an explosion at all ambient temperatures and that the vapor/air mixture will be too lean to ignite only at temperatures colder than — 49°F. A major mistake firefighters make is that they expect only a fire if a liquid is ignited at temperatures above its flash point. In reality, what occurs when the vapors of a flammable or combustible liquid are ignited is an explosion. The strength of the explosion depends on the type and amount of fuel present.
In the case of ethyl ether, its flash point and boiling point are so low that a tremendous amount of vapors will evolve from any spill or open container at “normal” temperatures in the range of 0° to 80°F. Its relatively lowboiling point of 94.1°F, the temperature at which maximum evaporation occurs at atmospheric pressure, indicates that this temperature is so close to “normal” temperatures that moreevaporation is occurring than with most other liquids.
Its relatively wide flammable range (and its low lower flammable limit of 1.8 percent) makes ethyl ether extremely dangerous. This characteristic and its low flash point mean that this product gets its vapors into the explosive range almost immediately on exposure to air. The danger from an explosion of ethyl ether vapors exists almost from the moment of a spill or release of vapors from a breached container. And if the low flash point, low boiling point, low lower flammable limit, and wide flammable range weren’t enough, the ignition temperature of 320°F is one of the lowest of the common flammableliquids. This means that ethyl ether vapors can explode whenever hot metal, superheated steam, or any other materal existing at a temperature of 320°F or higher comes in contact with them. No flame or spark is needed— although they will surely produce an explosion within the flammable range. These properties of ethyl ether have earned it a “4” rating in the flammability quadrant of the NFFA 704 hazard system.
An even more insidious hazard hides within the molecular structure itself. Ethers are hydrocarbon derivatives characterized by the presence of zan atom of oxygen covalently bonded between two hydrocarbon radicals. This structure is susceptible to invasion by another atom of oxygen, provided by atmospheric oxygen (0). This invasion can occur anytime ethyl ether is exposed to air, heat, or light. The extra oxygen atom bonds with the oxygen in the molecule, changing the oxygen radical (-()-) to the peroxide radical (-0-0-). This reaction can occur with any ether but is very common with ethyl ether. The resulting compound is diethyl peroxide, which because of its structure is classified ;LS an organic peroxide.
Organic peroxides are very unstable materials; they have the power (and the propensity) to detonate when heated or shocked. The amount of energy needed to heat or shock an organic peroxide is very low: The friction generated by turning the cap on a previously opened container is enough to detonate the peroxide. Indeed, the major cause of peroxide formation is the process of opening a container, exposing its contents to air, and subsequently closing the container. Peroxide crystals then form on the threads of the cap and/or neck of the container, and the energy generated from the friction caused by turning the cap can “set it off.” Small containers that have been opened should be disposed of after the contents have been disposed of properly and the container cleaned.
Small amounts of ethyl ether spilled on the floor or ground might be adsorbed by soil or other materials. Rather than completely evaporating, any material adsorbed (or absorbed) might convert to a peroxide in time, and the friction produced by someone walking on the crystals could detonate them. It is very important in the mitigation of an incident where ethyl ether has been spilled not only to recover as much of the liquid as possible (which may be extremely difficult because of the rapid evaporation rate) but also to make sure that any contaminated soil or other material is removed properly and then disposed of properly.
Ethyl ether is considered a stable chemical compound, but this description can be misleading. The product can decompose violently if heated. It also can be ignited with no apparent ignition source—-simply shaking the container can do it. If there is enough oxygen present to allow the vapors to be in the flammable range, vigorous agitation or shaking can produce static electricity, whose discharge via a spark can ignite the vapors. Its susceptibility to the formation of organic peroxides by partial oxidation also might be a surprise to someone who thought ethyl ether was a stable compound. It will react violently with several chemicals including the halogens (fluorine, chlorine, bromine, iodine), compounds made up of only the halogens (such as bromine pentafluoride and iodine heptafluoride), and all other strong oxidizing agents.
Being an extremely flammable liquid (making it an excellent fuel), ethyl ether never must be allowed to come in contact with strong oxidizing agents. Mixtures of ethyl ether and strong oxidizers are very unstable, producing potentially explosive materials. It is a general rule that oxidizers and fuels (anything that will burn) never must be stored together. At least one reference indicates that a potentially violent reaction may occur with mixtures of ethyl ether and strong bases.
IDENTIFICATION NUMBERS AND RATINGS
CAS
(Chemical Abstract Services) 60-29-7
STCC
(Standard Transportation Commodity Code) 4908157
RTECS
(Registry of Toxic Effects of Chemical Substances) KI5775000
UN/NA
(United Nations/North America) 1155
CHRIS
(Chemical Hazard Response Information System) EET
RCRA
(Resource Conservation and Recovery Act) U117
DOT
(U.S. Department of Transportation) Flammable liquid
NFPA 704 Rating
2-4-1
IMO
(International Maritime Organization) 3.1, flammable liquid
Ethyl ether once was the most common anesthetic used in U.S. hospitals. Its toxicity is relatively low but its narcotic power is high. The odor of ethyl ether is so strong that it can be detected in quantities as low as 0.5 ppm (parts per million in air). Its TLVTWA (threshold limit value-time weighted average) is 400 ppm, while its STEL (short-term exposure limit) is 500 ppm (for 15 minutes).
Exposure to high levels of ethyl ether vapors produces a wide range of symptoms including the lowering of body temperature, slowing of the pulse, and depression of the central nervous system. Other effects of overexposure range from a simple headache to unconsciousness.
Exposure to 100,000 ppm produces anesthesia in humans, while concentrations as low as 2,000 ppm cause dizziness. One reference states that the IDLH (immediately dangerous to life and health) limit is 19,000. An LC50 of 65,000 ppm for 100 minutes has been established.
Contact of the liquid with the skin causes defatting, cracking, and irritation. Contact with the eyes can cause irritation and temporary pain, but permanent injury has not been reported.
Ingestion of ethyl ether is rare, but symptoms similar to those of inhalation of high concentrations of vapors have been reported.
NONFIRE RELEASES
The release of a large amount of ethyl ether should trigger the community emergency response plan dictated by Title III of SARA (Superfund Amendments and Reauthorization Act). Environmental authorities immediately should be notified and other local agencies included in the plan also should respond. This poses a new problem for hazardous-materials incident commanders in that they must coordinate the activities of a large and varied group of emergency responders while concurrently attempting to bring the incident to a safe conclusion. Tile upside is that more experts will be on the scene to offer assistance and advice.
All the old rules of approach still apply. Approach from upwind and remove all possible ignition sources, remembering that the fire apparatus itself can be a source of ignition. Evacuate and secure the area and evacuate all unnecessary personnel for a minimum radius of one-half mile. Downwind evacuation may be required for a mile or more.
The violent explosion that will occur if a large volume of ethyl ether vapors has been liberated and then exposed to an ignition source is the major danger. Firefighters and other emergency responders may be lulled into a false sense of security if they believe that fire is the biggest hazard of a flammable liquid. Fire indeed may occur, but explosion is the first reaction that will occur if the vapors of a flammable or combustible liquid are ignited. The “fuel-air” explosive bomb recently developed by the military is a perfect example of the destruction that occurs when a fuel-air mixture is ignited. Ethyl ether’s high volatility guarantees that large amounts of vapor will be mixed with the air near the release.
The high vapor density of 2.55 means that the vapors will “hang together” and flow (gases and vapors are fluids) along low spots in the terrain. This poses great danger for any unsuspecting person who might be in a low-lying area or confined space where ethyl ether vapors have accumulated. Breathing concentrations of 10 percent or more will produce anesthesia, and an ignition source will cause an explosion.
Vapors being released from a leaking container or being liberated from a spill may be dispersed by the use of high-pressure spray or fog patterns. The spray or fog not only will speed up the dispersing of explosive ethyl ether vapors but also will dissolve the vapors out of the air. For this reason, all runoff water from this mitigation technique must be contained.
Any liquid being released from a container must be kept from spreading. Dikes pushed up from soil surrounding the spill can be used as a makeshift containment pond; a containment pit may be dug if equipment is available. A pit allows fewer vapors to evolve, since a dug pit usually has a smaller surface area than a pond. All other things being equal, a larger surface area will allow faster evaporation than a smaller surface area because more liquid is exposed to the atmosphere.
Fmergency responders must be extremely careful when choosing tools to use at the incident, since the slightest spark from metal tools or electrical discharge from any electrical device, including battery-operated devices, can be the ignition source for an explosion. Any heavy equipment used to create containment ponds or pits must not produce a metallic spark or electrical discharge. Keep in mind that an internal combustion engine could reach the very low ignition temperature of 320°F.
If liquid ethyl ether has been contained, it is advisable to cover the surface of the liquid to slow the evolution of vapors. Do this with sheets of compatible material. Some references suggest covering the surface with firefighting foam; since ethyl ether is soluble in water, alcohol-type foam is recommended. Some authorities, however, suggest regular foam. Both probably should be tried, and the foam that works better should be continued. Applying foam increases the volume of the liquid slightly, so care should be taken to prevent the escape of any liquid.
Once contained, ethyl ether may be suctioned into secure containers byprofessional salvagers. They have the proper education, training, and equipment to remove the product safely. Firefighters and other emergency responders should not be involved in salvage or cleanup operations because of the obvious danger and liability involved.
Any ethy’l ether remaining after suctioning may be absorbed by the application of cement powder, clay, peat moss, sand, saw dust, soil, vermiculite, or any other natural or commercial sorbent. This material then must be handled in the same manner as the pure product, since there still will be a chance of explosion and fire. It must be disposed of in a manner consistent with all federal, state, and local regulations. The environmental experts will determine the extent of contamination and the amount of soil and other material that must be removed.
It is absolutely necessary to remove all remaining ethyl ether because highly explosive organic peroxides might form once the ether is exposed to air. Any heat or friction that contacts these crystals will detonate them.
If the product cannot be removed immediately or covered effectively and if the containment area can hold the added volume, the ethyl ether can be diluted with water. Dilution effectively lowers the evaporation rate and raises the flash point, lessening the danger somewhat. It may not be feasible, however, to add enough water to render the product safe, so most danger still will remain.
Ethyl ether must be prevented from entering waterways or sewer systems. If it does enter a sewer, the sewage treatment plant must be notified immediately, and the entire sewer line must be monitored at every manhole and catch basin to determine if explosive vapors are present. The vapors will fill the sewer and flow downhill. A potentially explosive mixture surely will be present at any opening where the vapors could mix with air.
If the liquid enters a waterway, it will float on the surface while it dissolves. The speed at which it dissolves depends on the volume of water present and the speed at which the water is moving. The more rapid the movement of water, the faster it will dissolve. Notify all downstream users of the water immediately. The intake of the water into an industrial operation could be extremely dangerous, especially where the water is used to cool equipment or processes. This heating of the water will force the ethyl ether to evaporate, producing a possible explosive situation.
The environmental authorities will make suggestions on how to remove the product from the waterway, if at all possible. They also will monitor the flow of water and determine when the water is safe for use.
FIRE SCENARIO
Containers exposed to a fire’s radiated or conducted heat may overpressurize very rapidly, causing catastrophic failure of the container. The rise in pressure may be fast enough to overcome any safety-relief device. Firefighters never should let themselves get between a fire and containers of ethyl ether. Cooling water should be delivered to the containers if firefighters are not endangered.
Vapors venting through a safetyrelief device—such as a spring-loaded valve—will ignite explosively if they reach an ignition source. If ignited when first released, the tongue of the flame will add heat energy to what already is reaching the container. The tongue of flame should not be extinguished unless the flow of vapors can be immediately stopped.
In any case, any large amount of heat or impinging flame could cause a BLEVE (boiling-liquid, expanding-vapor explosion). An explosion of this type is particularly devastating, since essentially all of the energy’ of the ethyl ether will be released in one blast.
If containers are being impinged by flame, an explosion of the container is imminent. Cooling water should be applied only if no human life is put in jeopardy.
All methods of extinguishment may be ineffective in a large fire, but water spray and fog may cool the fire down and the application of foam may slow the evolution of vapors. Halon, dry chemical, and carbon dioxide might work on small pools of burning liquid. A serious threat of reignition exists because the ignition temperature of ethyl ether is so low and because any exposed metal heated by the fire will cause reignition if its temperature is at 320°F or higher. If no life is threatened and no property will be destroyed, it might be best to allow a difficult-to-extinguish fire to burn itself out while you protect exposures.
PROTECTIVE CLOTHING AND EQUIPMENT
Choose protective clothing and equipment that will prevent contact of the ethyl ether with the eyes or skin. Rubber gloves, aprons, and boots offer some skin protection; wear splashproof chemical goggles to protect the eyes. SCBA must be used for respiratory protection. Manufacturers of total encapsulating suits claim that suits made of butyl rubber, chlorinated polyethylene, neoprene/SBR (styrene-butadiene rubber), nitrile rubber, polyvinyl alcohol, polyethylene, polyethylene/ethylene vinyl alcohol, polyurethane, and Teflon will offer protection for some period of time. Since different references claim various levels of protection for these materials, contact the individual manufacturers of total encapsulating suits to determine the degree of safety offered by each material.
SYNONYMS
aether
anaesthetic ether
anesthesia ether
anesthetic ether
diethyl ether
diethyl oxide
ether
ethoxyethane
1,1 -oxybisethane
solvent ether
sulfuric ether
FIRST AID
For inhalation, move the victim to fresh air, keep him/her calm and warm. If the victim’s breathing has stopped or becomes labored, administer artificial respiration, being aware that such action might expose the first-aid giver to the material in the victim’s lungs and/or vomit. Seek immediate medical attention.
For eye contact, flush the eyes immediately for at least 15 minutes, lifting the eyelids occasionally. Seek immediate medical attention.
For skin contact, wash the affected areas with large amounts of soap and water. If irritation continues after washing, seek medical attention.
For ingestion, the references do not agree. At least one says that a conscious victim should drink a strong solution of salt and water immediately and that vomiting should be induced. Never make an unconscious person drink anything or vomit. Immediate medical attention is needed. Another reference says do not induce vomiting, while a third says to induce vomiting only if immediate medical attention is not available.*
