Acrolein

Acrolein

HAZARDOUS MATERIALS

CHEMICAL DATA NOTEBOOK SERIES #36

ACROLEIN is a toxic, flammable, unstable, corrosive, irritating, highly volatile, clear, colorless or yellowish liquid with a very powerful acrid and disagreeable odor. It is used as an intermediate in the manufacture of glycerol, perfumes, pharmaceuticals, and some plastics. It is a herbicide and can be an ingredient in chemical weapons. It is also an odorant in some gases, and is used in certain chemical synthesis reactions.

PROPERTIES

Acrolein has a flash point of — 15°F, an ignition temperature of 428°F, and a flammable range of 2.8% to 31%. It has a specific gravity of 0.84, a vapor density of 1.93, and a molecular weight of 56. It boils at 126.5°F., freezes at — 125°F, and is soluble in water. Its chemical formula is C2H3CHO, and its structural formula is:

H H O

H — C = C — C— H

HAZARDS

Acrolein is a very flammable liquid by three different measurements. By definition, a flammable liquid is a liquid with a flash point below 100°F, and acrolein’s flash point is — 15°F. This means that at any temperature from — 15°F and above, there will be sufficient vapors to form an ignitable mixture with the air near the surface of the liquid. Its very low ignition temperature allows these vapors to be ignited by all common ignition sources, including a cigarette.

Adding to the danger is the relatively wide flammable range of 2.8% to 31%. This means that the danger of ignition exists over an extremely wide range of concentration and that it will be very difficult to find a situation above the upper flammable limit (where the vapor concentration is too rich).

Its vapor density of 1.93 means that the vapors of acrolein will flow along low spots in the terrain and may tend to accumulate in low areas and/or enclosed spaces. These accumulations are hazardous from both flammability and toxicity standpoints. Although all the flammability parameters of acrolein point to an easy ignition of its vapors (and most firefighters equate ignition of the vapors of a flammable liquid with fire), the first event that occurs upon ignition of flammable vapors is an explosion, which is usually followed by a fire.

The vapors of acrolein are extremely toxic, and their odor can usually be detected at levels of from 0.05 ppm (parts per million of air) to 0.4 ppm. The TLV-TWA (threshold limit value -time weighted average) is 0.1 ppm and the STEL (short term exposure limit) is 0.3 ppm (for 15 minutes).

Inhalation of acrolein vapors may cause coughing, dizziness, headaches, irritation, stomach upset, pulmonary edema, cyanosis, and death. Fatalities have been reported after exposure to levels of 150 ppm for 10 minutes. Some symptoms, such as chest pains and edema, may be delayed.

The odor of acrolein is very irritating, acrid, piercing, and eventually unbearable. Almost everyone has inhaled small quantities of acrolein at some point, and its odor may have been masked by other odors. Acrolein is produced in relatively large quantities by burning wood and wood products such as paper or cardboard. Anyone sitting around a campfire and enjoying the smell of burning wood has reacted quickly to acrolein when the wind shifted and they were caught by the drifting smoke. Acrolein is what makes you cough and react violently to wood smoke. It is what causes the firefighter without a mask to cough and gag, eyes tearing and nose running. Constant exposure to this toxic material may contribute to lung disease. The toxic potency of acrolein may be as low as 30 ppm, which means breathing this amount will be fatal in 10 minutes or less. Acrolein may be the “supertoxicant” for which combustion toxicologists have been searching for several years.

ACROLEIN

Contact with liquid acrolein will cause skin burns; burns of the eyes can be very severe. Ingestion of the liquid can cause severe irritation of the mouth and tongue, esophagus, and stomach, and can produce severe gastrointestinal problems.

As shown earlier, acrolein is a relatively small molecule with a double bond. One of its chemical properties is that it is a monomer, capable of polymerization. When in a reactor and properly controlled, the polymerization reaction is not hazardous. However, if a container of acrolein undergoes uncontrolled or runaway polymerization, the container may undergo catastrophic failure, and an explosion resembling a BI.EVE may occur.

To prevent polymerization during transportation (containers range from drums to rail tank cars) and/or storage, an inhibitor is usually added at about 0.1% to 0.25%. This inhibitor—in acrolein’s case, hydroquinone—will act to prevent polymerization under normal circumstances. However, if the container is subjected to heat and pressure, the inhibiting action of the hydroquinone may be overcome, or driven out of the acrolein by evaporation. Once this occurs. runaway polymerization is imminent. Certain chemicals, such as amines, ammonia, or caustics will cause polymerization to begin in a violent manner.

Other than the tendency to polymerize, acrolein is considered a stable chemical. However, it will react with alkaline compounds, amines, 2-aminoethanol, ethylene diamine, ethyleneimine, oxidizers, salts, strong acids, sulfur, and thiourea. The pure material will react with air, heat, and light to polymerize, and its vapors will polymerize in air. The runaway polymerization is particularly hazardous when the liquid is in a container, since sufficient heat may be generated to reach its lowignition temperature, and pressure may rise very rapidly.

GLOSSARY

Caustics—Strongly alkaline substances that have a corrosive or irritating effect on living tissue.

Flammable range—The percentage of gas or vapor in air between the upper and lower flammable limits.

Lower Flammable Limit—The minimum percentage of gas or vapor in air, below which ignition will not occur (the mixture is too lean). Also called the Lower Explosive Limit (LEL).

Monomer—A “tiny” molecule that possesses the unusual chemical property of being able to react with itself to form polymers.

Polymer—A “giant” molecule made up of thousands of monomer molecules that have reacted with themselves in a special type of chemical reaction called polymerization.

Upper Flammable Limit—The maximum percentage of gas or vapor in air, above which ignition will not occur (the mixture is too rich). Also called the Upper Explosive Limit (DEL).

Vapor density—The relative density of a vapor or gas (with no air present) as compared to air. The higher the vapor density of a gas or vapor, the “heavier” it is than air. Any vapor density less than 1.0 means it w ill rise in air. and any vapor density greater than 1.0 means it will sink.

Vapor pressure—The pressure exerted by a gas or vapor on the sides of a container.

Volatility—The tendency of a liquid to evaporate at a given temperature. The higher a liquid’s volatility, the faster it will evaporate.

NONFIRE RELEASE

The proper environmental authorities must be notified immediately of any actual or potential spill or release of acrolein, as well as any other hazardous material. These authorities should be on-scene during the incident for their advice on methods and procedures to use in preventing the spread of the material.

Acrolein’s high vapor pressure of 4.16 psia at 68°F means that the unconfined liquid will evaporate very rapidly. Therefore, any spill of the liquid or any opening in the container will release large volumes of explosive and toxic vapors. These vapors will then move downwind, posing explosive and toxichazards to the general population. Evacuation is a tactic that must be considered very early in the incident. A minimum evacuation and withdrawal radius is 3,000 feet from a rail car or tank wagon, with consideration of evacuation downwind as far as necessary, perhaps several miles.

Water fog or spray may be used to absorb acrolein vapors from the air, and the force of the spray will also help disperse them. Consideration must be given to containing the runoff generated in this manner.

The generation of vapors may be slowed somewhat by the application of alcohol-type foam to the surface of the spilled liquid. Breakdown of the foam may necessitate increased application, and this may add to the volume of the liquid.

Generation of vapors may also he slowed by the addition of water to the liquid, thus diluting it. Again, water will add to the volume of the liquid and will spread contamination if not contained.

Containment may be effected by building containment ponds of soil, clay, sand, and other sorbent material. A containment pit may be dug to hold the liquid, and the liquid may be led to it by the digging of trenches. In all cases, nonsparking compatible tools, equipment, and protective clothing must be used to prevent ignition and hazardous exposure to the first responders. All contact with the material during the incident and all cleanup activities must be handled by professionals in the field.

Once contained, the material may be salvaged by pumping the liquid from the containment pond or pit into secure containers. If the release is in the form of a leak, it may be possible to collect the leaking liquid in a container and pump it back into the original leaking container until it can be transferred to one that’s secure. Again, the equipment used should be compatible with the acrolein and produce no sparks. Salvage of any sort should not be attempted by emergency responders. This job should be left to the professional salvage firms whose employees should be properly educated, properly trained, and properly equipped.

Use of containment ponds and pits will help prevent the spread of contamination, but the pond or pit itself will have caused contamination by percolation into the soil or into the side walls of the pit. The environmental authorities will determine the extent to which soil and other contaminated material wall have to be removed.

Once as much of the liquid that can be pumped out is gone, an adsorbent material may be added to the remaining acrolein to aid in its removal. Activated carbon, peat moss, and commercial adsorbents may be used. Care must be exercised during removal of those contaminated adsorbents, since the acrolein must be disposed of under the same environmental regulations as the spilled liquid and contaminated soil.

Acrolein must not be allowed to enter sewers or waterways. Entry into a sewer will allow the spread of flammable vapors throughout the municipality underground, and the relatively high upper flammable limit could allow explosions to occur throughout the sewer system. Sewage treatment plants must be warned of its approach.

If the material enters a waterway, it will begin to dissolve immediately. Attempts should be made to dam the waterway or to divert the water to an impoundment area. This will prevent movement of the acrolein downstream, but may spread contamination at the containment site. Impounded contaminated water may be pumped into secure containers (again, with compatible equipment). All downstream users of the water must be warned immediately; the environmental authorities on the scene will monitor any movement of the material downstream.

In all releases of hazardous materials, the users and the manufacturers must be contacted immediately and consulted in the safe handling of the product. Many chemical companies provide emergency spill teams, which will respond anywhere in the country that their material has been released. On some occasions, they might even respond to a spill of a material manufactured by someone else.

The wise incident commander will use every’ resource available in order to effect a safe conclusion to the incident. He must be prepared to take no action, aside from containment of the material and/or evacuation of the population. He also will know that the forces in his command should not involve themselves in salvage and/or cleanup.

FIRE SCENARIO

If containers of acrolein are threatened by radiated heat from a nearby fire or are being heated by impinging flame, immediate withdrawal is advised. Cooling of the heated container must be done from as far away as possible using unmanned appliances to protect the emergency responder.

Containers of acrolein are subject to pressure rise from two sources. First, as the liquid is warmed, vapors will be generated that cause pressure within the container to rise. A spring-loaded pressure relief valve (if there is one) will operate at its designed pressure, and highly flammable vapors will be vented to the atmosphere. If the heat causing the pressure rise is from impinging flame, the escaping vapors will probably ignite and burn at the vent. No attempt should be made to extinguish the flames, since a rapid buildup of unignited vapors may accumulate and an explosion might occur. Efforts must be directed to cooling the container. If successful, the vapors will cease venting as the valve reseats itself.

If the vapors are produced faster than can be relieved by the vent, the pressure will continue to rise until the design strength of the container is reached. The container will then “come apart” catastrophically, releasing flammable liquid and vapor to the environment, plus shrapnel in the form of metal pieces of the container.

The other cause of pressure rise may be more rapid. If the heated container is vented, the inhibitor may be driven out of the liquid and the acrolein may polymerize rapidly, producing a great amount of heat. This might vaporize the contents instantaneously, producing a rapid explosion of the container. In either case, the explosion could be fatal to anyone within 3,000 feet.

ACROLEIN

If spilled acrolein is ignited, alcoholtype foam, water spray or fog, carbon dioxide, and dry chemicals are effective extinguishers, depending on the size of the spill, and wind, weather, and terrain conditions.

Firefighters should be aware of the contents of ail containers exposed to lire and should never let themselves get between the containers and a fire. If the contents are unknown, they should be treated as if they contain a highly volatile flammable liquid, such as acrolein.

PROTECTIVE CLOTHING AND EQUIPMENT

Protective equipment and clothing should be selected to prevent contact of the product with the skin and eyes, and the inhalation of vapors must be prevented. This means that positive-pressure self-contained breathing apparatus should be used in all contact with acrolein, and rubber gloves and boots, chemical splash-proof goggles, and face shields should be worn.

Total encapsulating suits should be used by any exposed personnel. Manufacturers of such suits provide technical information concerning their claims that certain materials offer protection tor exposure to certain chemicals. Acrolein is so corrosive to many polymers that it may be difficult to find a material that offers protection. Purchasers will have to ask the suppliers for their recommendations. Some materials offer protection for limited periods of time, and the suit will be affected to the point it may be rendered useless for future protection. One reference suggests that neoprene not be used.

FIRST AID

For inhalation, the victim must be moved to fresh air and kept quiet and warm. Artificial respiration is necessary if breathing becomes difficult or stops. The first aid provider must be aware that mouth-to-mouth resusitation will expose him to the acrolein in the victim’s lungs and/or vomit. Get medical attention quickly.

For eye contact, the eyes must be flushed immediately with water and continued for fifteen minutes, occasionally lifting the eyelids. Medical attention must be sought immediately for burns and irritation.

For skin contact, the victim’s contaminated clothing must be removed, and the contacted skin must be washed with large amounts of water. Get medical attention if there are signs of irritation or burning.

For ingestion, administer a strong solution of salt water and induce vomiting if no medical attention is available immediately. However, if medical attention is available immediately, do not make the victim vomit. And remember, never try to make an unconscious person drink anything.*

IDENTIFICATION NUMBERS AND RATINGS

CAS

(Chemical Abstract Service)

107-02-8

STCC

(Standard Transportation Commodity Code)

4906410

UN/NA

(United Nations/North America)

1092

RTECS

(Registry of Toxic Effects of Chemical Substances)

AS1050000

CHRIS

(Chemical Hazard Response Information System) ARL

RCRA Waste Number

(Resource Conservation and Recovery Act)

POO 3

NFPA 704 Rating

3-3-2

DOT

(U.S. Department of Transportation)

Flammable liquid

IMO

(International Maritime Organization)

Flammable liquid, 3-1

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