CHEMICAL DATA NOTEBOOK SERIES #115: DIISOPROPYL ETHER
BY FRANK L. FIRE
Diisopropyl ether is a flammable, highly volatile, anesthetic, irritating, mildly toxic, clear, colorless liquid with a sweet, pungent, and slightly sharp but pleasant odor. Its major uses are as an extractant; a solvent for animal, vegetable, and mineral oils as well as resins and waxes; and as a raw material in the manufacture of rubber cements and paint and varnish removers.
Diisopropyl ether has a flash point of -18°F, an ignition temperature of 830°F, and an explosive (flammable) range of 1.4 to 21 percent in air. It has a specific gravity of 0.724, a molecular weight of 102, and a vapor density of 3.52. Its boiling point is 153.5°F, its freezing point is -124.4°F, and it is slightly soluble in water. Its molecular formula is C6H14O.
Flammability is diisopropyl ether`s major hazard. The implication of its extremely low flash point of -18°F means that diisopropyl ether will generate sufficient vapors to produce an explosion at all normal ambient temperatures and that only at temperatures colder than -18°F will the vapor/air mixture be too lean to ignite and explode. Many emergency responders mistakingly believe that only a fire will occur at temperatures above a liquid`s flash point, given a suitable ignition source. In reality, an explosion occurs when flammable or combustible liquid vapors are ignited. Only the type of fuel and the amount present determine the severity of the explosion.
Diisopropyl ether is extremely volatile, which means it will evaporate very quickly at ambient temperatures, producing very large amount of dangerous vapors. Those vapors, being 3.52 times heavier than air, will “hang together” for a long time, moving very slowly “downhill,” even without a gentle breeze. However, a strong breeze will disperse the vapors in air, the degree and speed of dispersion depending entirely on the wind`s strength and direction.
The flash and boiling points of diisopropyl ether are so low that at “normal” temperatures, in the range of 0°F to 80°F–found in most parts of the country at most times of the year–a tremendous amount of vapors will evolve from any spill or open container of diisopropyl ether. The relatively low boiling point of 153.5°F, the temperature at which maximum evaporation occurs at atmospheric pressure, means that even though this temperature is very much above “normal” temperatures, more evaporation occurs than with most other liquids.
Its relatively wide explosive (flammable) range and its low lower explosive (flammable) limit of 1.4 percent make diisopropyl ether extremely dangerous. Joining this with its low flash point means that at most climatic conditions, this product gets its vapors into the explosive range almost immediately. The danger that diisopropyl ether vapors will explode exists almost from the moment a liquid spill or vapor release from a breached container occurs. And, as if the low flash point, low boiling point, low lower explosive limit, and wide explosive range weren`t enough, the ignition temperature of 830°F is well within the reach of all common ignition sources–meaning that diisopropyl ether vapors can explode whenever hot metal or any other material existing at a temperature of 830°F or higher comes into contact with them. No flame or spark is needed, although the presence of such flames will surely produce an explosion within the explosive range. All these properties make diisopropyl ether a very flammable liquid.
An even more deadly hazard hides within the molecular structure of diisopropyl ether. All ethers are hydrocarbon derivatives characterized by the presence of an oxygen atom covalently bonded between two hydrocarbon radicals. This molecular structure is very susceptible to oxidation–that is, another atom of oxygen, provided by atmospheric oxygen (O2), can join with the oxygen atom already present in the diisopropyl ether molecule to form the peroxide radical. This invasion can occur anytime diisopropyl ether (or, for that matter, any ether) is exposed to air, heat, or light. This extra oxidation reaction will change the oxygen radical (-O-) to the peroxide radical (-O-O-). The resulting compound is diisopropyl peroxide, which is classified as an organic peroxide due to it structure.
Organic peroxides are extremely unstable materials and 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–that is, the friction generated by turning the cap on a previously opened container is enough to detonate the peroxide formed on the threads. The major cause of the formation of most organic peroxides is opening a container, subsequently exposing its contents to air, and closing the container. Peroxide crystals will form on the cap`s threads and container`s neck; the energy generated from the friction caused by turning the cap can set it off. Once small containers of diisopropyl ether, or any ether, have been opened, the contents should be properly disposed of and the container cleaned and disposed of.
Although the propensity to form organic peroxides is common among all ethers, the reaction will occur much faster with diisopropyl ether than with some common ethers, such as ethyl ether.
Small amounts of diisopropyl ether spilled on the floor or ground may be adsorbed by soil or other materials. Rather than completely evaporating, the liquid material will be adsorbed (or absorbed) and will convert to an organic peroxide in a relatively short time. Even the energy caused by the friction produced by a person`s walking over the crystals could cause a detonation. When mitigating any incident involving a spill of diisopropyl ether, not only must as much of the liquid as possible be recovered (which may be extremely difficult because of the rapid evaporation rate), but trained salvage personnel also must properly remove and dispose of any contaminated soil or other material.
Diisopropyl ether is described as a stable chemical compound, but this description can be misleading. If the product is heated, it can decompose violently. It can be ignited easily and explosively, even with no apparent ignition source; a simple agitation of the container is all that may be needed. If enough oxygen is present to allow the vapors to be in the explosive range, vigorous agitation or shaking can produce static electricity; its discharge via a spark can ignite the vapors. Diisopropyl ether`s susceptibility to form organic peroxides by partial oxidation might come as a surprise to someone who thinks of diisopropyl ether as a stable compound.
In addition, diisopropyl ether will react violently with all strong oxidizing agents, including the oxygen in air, chromic acid, the halogens (fluorine, chlorine, bromine, and iodine), hydrogen peroxide, nitric acid, ozone, perchloric acid, and all other strong oxidizing agents.
Since it is an extremely flammable liquid (making it an excellent fuel), diisopropyl ether must never be stored near or come in contact with strong oxidizing agents. As a general rule: Oxidizers and fuels (anything that will burn) must never be stored together.
According to at least one reference, a potentially violent reaction may occur when diisopropyl ether and propionyl chloride are mixed.
The odor of diisopropyl ether is so strong that it can be detected in quantities as low as 0.017 ppm (parts per million of air). Its TLV-TWA (threshold limit value-time weighted average) is 250 ppm, or 1,040 mg/m3 (milligrams per cubic meter). Its STEL (short-term exposure limit) is 310 ppm for 15 minutes, or 1,300 mg/m3. Exposure to high levels of diisopropyl ether vapors will produce a wide range of symptoms, including dizziness, narcosis, irritation of the eyes, slowing of the pulse, and depression of the central nervous system. Other effects of overexposure range from a simple headache to unconsciousness and death. Exposure to 60,000 ppm has produced death in laboratory animals.
If the liquid contacts the skin, it will cause defatting, cracking, and irritation.
Contact with the eyes can cause irritation and temporary pain, but injury usually is minor.
Ingesting diisopropyl ether can cause intense and rapid intoxication involving diarrhea, gastrointestinal irritation, nausea, vomiting, and even death.
The release of any substantial amount of diisopropyl ether must trigger the community emergency response plan dictated by Title III of SARA (Superfund Amendments and Reauthorization Act). Notification of the proper environmental authorities should be automatic and immediate, and all other local emergency response agencies included in the plan must also respond.
Follow the rules for approaching any flammable liquid: Approach from upwind and uphill, and immediately eliminate all possible ignition sources, remembering that the fire apparatus itself can be a source of ignition. Evacuate and secure the immediate areas of the release. All unnecessary personnel must be made to leave this “hot” area. Evacuate for a minimum radius of one-half mile or for a wider distance if the spill is large. If necessary, evacuate downwind for a mile or more.
A violent explosion will be the major immediate danger if a large volume of liberated diisopropyl ether vapors is exposed to an ignition source. Firefighters and other emergency responders may be lulled into a false sense of security if they believe the biggest hazard of a flammable liquid is the threat of fire. As previously explained, fire may occur; but if the vapors of a flammable or combustible liquid are ignited, an explosion will be the first reaction. Diisopropyl ether`s high volatility guarantees that large amounts of vapor will mix with the air near the release and immediately downwind or downhill.
The very high vapor density of 3.52 means that the vapors will “hang together” and flow (gases and vapors are fluids) along low spots in the terrain. This situation is hazardous for unsuspecting and unprotected persons who may be in the same low-lying area or confined space as the diisopropyl ether vapors. Breathing concentrations of six percent or more will produce anesthesia, and an ignition source will cause an explosion.
You may disperse diisopropyl ether vapors released from a leaking container or liberated from a spill with high-pressure spray or fog patterns, which accelerate vapor dispersement and also will dissolve a small amount of the vapors out of the air. Contain all runoff water.
Liquid diisopropyl ether being released from a container must be kept from spreading away from the immediate release site. You can do this by constructing dikes by pushing up the soil surrounding the spill to form a makeshift containment pond or by digging a containment pit if the proper equipment is available. Fewer vapors will evolve from a containment pit since it usually has a smaller surface area than a pond. In any situation where evolution of vapors is a concern, all other things being equal, evaporation will be faster when the area surface is larger because more liquid is exposed to the atmosphere.
Tools used at incidents involving flammable liquids must be chosen carefully. The slightest spark from metal tools or electrical discharge from an electrical device, including battery-operated devices, can suffice as the ignition source needed to produce an explosion. A metallic spark or electrical discharge from heavy equipment used to create containment ponds or pits also can serve as ignition sources.
Contained liquid diisopropyl ether should be covered with sheets of compatible material to slow the evolution of vapors. Some references suggest covering the surface with firefighting foam. Since diisopropyl ether is slightly soluble in water, an alcohol-type foam is recommended. However, some authorities suggest regular foam. Both foams probably should be tried. Continue to apply whichever foam works better. The foam will increase the volume of the liquid slightly; take steps to ensure that no liquid escapes. Once contained, professional salvagers may suction diisopropyl ether into secure containers. These professionals will have the proper education, training, and equipment to safely remove the product. Firefighters and other emergency responders should not be involved in salvage or cleanup operations because of the obvious danger and liability involved.
Any diisopropyl ether remaining after suctioning may be absorbed by applying cement powder, clay, peat moss, perlite, sand, sawdust, soil, vermiculite, or any other natural or commercial sorbent. This material must then be handled in the same manner as the pure product, since there will still be a chance for explosion and fire. The absorbed ether could oxidize to form an explosive organic peroxide. The contaminated sorbent must be disposed of in a manner consistent with federal, state, local, and safety regulations. The environmental experts will determine the extent to which contamination has occurred and the amount of soil and other material to be removed.
All remaining diisopropyl ether must be removed because once it is exposed to air, highly explosive organic peroxide crystals may form and detonate as a result of heat contact or friction.
Prevent diisopropyl ether from entering waterways and sewer systems. If it does enter a sewer, immediately notify all sewage and water-treatment plants, and monitor the entire sewer line at every manhole and catch basin to determine if explosive vapors are present. The vapors will fill the sewer and flow downhill. An explosive mixture will surely be present at any opening where the vapors may mix with air. The potential for the mixing of a powerful oxidizer (the peroxide) with fuel (the organic material in the sewer) poses an extreme danger.
Should liquid diisopropyl ether enter a waterway, it will float on the surface while it very slowly dissolves. The speed at which it will dissolve depends on the volume of water present, the temperature of the water (warmer water will dissolve liquids and solids more rapidly than colder water), and the speed at which the water is moving. The material will dissolve more rapidly in fast-moving water. Immediately notify all downstream users of the water of the dangers of diisopropyl ether and the resulting organic peroxide. Intaking such water into an industrial operation, especially where the water is used to cool equipment or processes, will be extremely dangerous. Heating the water will force the diisopropyl ether to evaporate, producing a potential explosive situation and hastening the formation of the peroxide radical.
The environmental authorities will suggest ways to remove the product from the waterway, if at all possible, and constantly monitor the flow of water to determine when it is safe for use.
Containers exposed to the radiated or conducted heat of a fire may overpressurize rapidly and cause the container to fail catastrophically. The pressure rise may be fast enough to overcome any safety relief device. Never get between a fire and containers of diisopropyl ether. If it can be done without endangering firefighters, cooling water should be applied to the containers. Heat and pressure will cause the ether to rapidly convert to organic peroxide. A detonation from the pressure on the peroxide formed is very likely.
If a safety-relief device, such as a spring-loaded valve, is present, vapors venting through this device will ignite explosively if they reach an ignition source. If the vapors were ignited when first released, the tongue of flame will add heat energy to that already reaching the container. Do not extinguish this tongue of flame 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 diisopropyl ether and any formed peroxides will be released in one gigantic blast.
If diisopropyl ether containers are being impinged by flame, an explosion of the container is imminent. Apply cooling water only if no human life is jeopardized by this action.
All methods of extinguishment may be ineffective in a large fire, but water spray and fog may cool the fire down; and applying foam may slow the evolution of vapors. A serious threat of reignition exists because the ignition temperature of diisopropyl ether is so low and any exposed metal heated by the fire will cause reignition if its temperature is at 830°F or higher. If the fire does not threaten life and it will not destroy property and if you are experiencing difficulty in extinguishing it, it may be best to allow the fire to burn itself out while protecting exposures during the burnout.
PROTECTIVE CLOTHING AND EQUIPMENT
Choose protective clothing and equipment that will prevent diisopropyl ether from contacting the eyes and skin. Rubber gloves, aprons, and boots may protect skin; wear splashproof chemical goggles to protect the eyes. Positive-pressure self-contained breathing apparatus (SCBA) must be used for respiratory protection. One reference claims that total encapsulating suits made of chlorinated polyethylene, neoprene, nitrile rubber, polyvinyl alcohol, and Viton® will offer protection for some period of time. Other references claim no material will provide more than a few minutes of protection. Since different references claim differing levels of protection for these materials, contact the individual manufacturers of the total encapsulating suits and diisopropyl ether to inquire about the degree of safety offered by each recommended material.
Inhalation. Move the victim to fresh air; keep him calm and warm. If 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 vomit. Seek immediate medical attention.
Eye contact. Flush the eyes immediately for at least 20 minutes, lifting the eyelids occasionally. Immediate medical attention is required.
Skin contact. Gently remove contaminated clothing and wash the affected areas with large amounts of soap and water. If irritation continues after washing, seek medical attention.
Ingestion. If the victim is conscious, make him drink large quantities of water immediately, and induce vomiting. Never try to make an unconscious person drink anything or vomit. Seek immediate medical attention.
IDENTIFICATION NUMBERS AND RATINGS
(Chemical Abstract Services)
(Standard Transportation Commodity Code)
(Registry of Toxic Effects of Chemical Substances)
(United Nations/North America)
(Resource Conservation and Recovery Act)
(Chemical Hazard Response Information System)
(U.S. Department of Transportation)
NFPA 704 Rating
(National Fire Protection Association)
(International Maritime Organization)
3.1, flammable liquid
FRANK L. FIRE is the vice president of marketing for Americhem, Inc. in Cuyahoga Falls, Ohio. He`s an instructor of hazardous-materials chemistry at the University of Akron as well as an adjunct instructor of haz mats at the National Fire Academy. Fire is the author of The Common Sense Approach to Hazardous Materials and an accompanying study guide, Combustibility of Plastics, and Chemical Data Notebook: A User`s Manual, published by Fire Engineering Books. He is an editorial advisory board member of Fire Engineering.