CHEMICAL DATA NOTEBOOK SERIES #96: DIMETHYLAMINE
Dimethylamine is a flammable, toxic, corrosive, irritating, colorless, foul, fishysmelling gas that usually is shipped as a liquid under its own pressure. At concentrations above 100 ppm (parts per million of air), the substance’s odor changes from fishy to ammonia-like. It is a very widely used raw material, required in the manufacture of such diverse products as acid gas absorbents, antioxidants, detergents, dyes, fuel, gasoline stabilizers, leather, pesticides, pharmaceuticals, plastics, rubber, soaps, surfactants, and textile chemicals. It also is used as a rocket fuel component, a solvent, and a stabilizer for some plastics.
Dimethylamine exists both in anhydrous form and in aqueous solutions. In anhydrous form, dimethylamine is a gas and therefore has no flash point. However, since it is shipped in its liquefied form, two references list its flash point as -18″F and 2()‘’F. respectively. Aqueous solutions of 25 percent dimethylamine are listed as flammable liquids with a flash point of 42″F, and solutions containing 40 percent dimethylamine have a flash point of -18°F. Its ignition temperature is 756-F, and its explosive range is from 2.8 to 14.4 percent in air. The liquid has a specific gravity of 0.67, a molecular weight of 45, and a vapor density of 1.55. It freezes at -134″F, boils at 44.4-F, and is extremely soluble in water. Dimethylamine’s molecular formula is (CH,)2NH.
Dimethylamine’s major hazard is that it is a flammable gas. It has a fairly wide explosive range (I 1.6 percent), and its ignition temperature (736-F) is low enough to be reached by any common ignition source. As a gas, it is already in the proper form to burn; in liquefied form (and aqueous form, according to one reference), its flash point is -18°F.
At all normal ambient temperatures, liquefied or an aqueous solution of dimethylamine will produce vapors sufficient to form an ignitable mixture with the air near its surface. Its vapor density of 1.55 means it will sink to the ground and How along low spots in the terrain. When it meets an ignition source, it will explode and flash back to its source.
Dimethylamine is a toxic gas, with a TLVTWA (threshold limit value-time weighted average) of five ppm and an STEL (shortterm exposure limit) of 15 ppm. Anyone caught without proper respiratory protection in a confined space with a sufficient concentration of dimethylamine will quickly be overcome or, at the least, very sick. Its odor is so powerful it may be detected at quantities as low as 0.01 ppm. If inhaled in low concentrations, dimethylamine can cause symptoms such as irritation of the nose, throat, and lungs, producing breathing difficulties, coughing, and a sore throat. High concentrations can cause immediate or delayed pulmonary edema. After becoming sensitized to dimethylamine through exposure to other amines and chemicals, a person’s reaction to high concentrations of dimethylamine will become more severe.
Dimethylamine is one of the final breakdown products of nitrogen-containing plant and animal tissue, including human tissue. Health-care workers have been known to describe human bodies as giving off an “ammonia-like” smell—the culprit is most likely dimethylamine. The rapid and violent reaction to the gas in one particular case in California probably occurred because the health-care workers had previously been exposed to other amines and certainly to other chemicals.
Dimethylamine is such a foul-smelling gas that almost anyone smelling any significant quantity may get sick to the stomach. Anyone who has discovered a dead body, especially one that has been undiscovered for a few days at high temperatures, has been exposed to dimethylamine. Deliberately burning coffee grounds in a frying pan. satu rating the air with cheap cigar smoke, or smearing a menthol gel under the nose may be the only ways to mask the sickening smell. Dimethylamine is also a lachrymator—that is. low concentrations of the gas will cause rapid tearing of the eyes. The irritation may be so severe that the eyes may be forced closed.
Dimethylamine is corrosive to aluminum, copper and its alloys, tin, and zinc (which means it will corrode galvanized surfaces). It will attack some types of plastics and rubber. including coatings made from those materials. Ammonia may be released as a result of its corrosive activity.
Although it usually is considered a stable chemical, dimethylamine will react, sometimes violently, with acid chlorides, acidic anhydrides, halogens, some cleaning solutions. strong acids, and strong oxidizers. It will react explosively with acrylaldehyde and mercury.
Dimethylamine is such a hazardous material that the imminent release from even a small container should activate the community’s emergency response plan. Explosions and toxicity will be the first concerns of emergency responders.
In the case of a leaking container of dimethylamine, approach from upwind and uphill, remove all unauthorized personnel from the danger area, and prevent anyone from entering. Eliminate all possible ignition sources, and ensure that all emergency responders are wearing the proper respiratory protection.
Evacuation of all nonemergency personnel and all civilian personnel should be your number-one concern. Consider evacuation distances of one mile or more, depending on the weather, wind direction and speed, the si/e of the container, and the amount of material released.
If the container is leaking a small amount of liquefied dimethylamine, all of dimethylamine’s hazardous properties must be considered before an attempt is made to stop the leak. In cases where small cracks or holes appear in containers, many emergency responders will try to plug the leak quickly, as they have done successfully with other, less hazardous materials. No attempt should be made to plug a dimethylamine leak unless it can be done with absolute safety. Use tools that are nonsparking and of compatible metals; patch or plug with materials that will not be attacked by the dimethylamine. Never approach a leaking container of dimethylamine unless you are totally protected from the gas, and never come in contact with the liquid.
Determine how much dimethylamine gas is flowing away from the release to ensure that exposed areas are protected. A spill with a large surface area will evolve more gas, since the evaporation of the liquid depends partially on the amount of liquid exposed to the atmosphere. For this reason, a containment pit dug to hold the released dimethylamine will evolve less gas than a large containment pond created by pushing up soil and other material around the spill. Covering the pit or pond with covers made of compatible material will slow the evolution of the gas. If the pit or pond can safely hold additional volume, you can add water to dilute the liquid dimethylamine and slow gas evolution.
Any time liquefied dimethylamine is spilled, it will generate very large amounts of gas. The evolved gas will be dispersed quickly and harmlessly by a strong wind or by the action of high-pressure water spray or fog. Water applied in this form will dissolve the dimethylamine gas, while the turbulence of the application will help disperse it. Contain all water used in this manner, since it will be contaminated with dimethylamine.
Use diking or other means to prevent liquid dimethylamine from entering waterways or sewer systems. The material should be pumped into secure containers by qualified, professional salvage firm personnel. Firefighters should not be involved in such salvage or cleanup operations.
If dimethylamine enters a waterway, notify all downstream users immediately. If possible. divert contaminated water into a lowlying area where techniques to remove the dimethylamine can be employed. If the stream or river is fast-moving, natural dilution may eliminate some hazards. Other problems, including the death of waterfowl, fish, and other aquatic animals, will be presented should the material enter a pond or lake. The environmental authorities activated by the community’s emergency response plan will make the final judgment on the safety of the water.
Entry of liquefied dimethylamine into a sewer system may be prevented by damming all catch basins and manholes. If dimethylamine does enter a sewer, notify the sewage treatment facility at once. As the liquid evaporates, much of the sewer system may fill up with flammable, toxic gas. Explosions are possible wherever the gas enters its flammable range and encounters an ignition source.
If a container of dimethylamine is leaking gas. consider using the dispersal techniques described above. Once again, do not attempt to plug the leak unless you can provide total safety for the responders involved.
IDENTIFICATION NUMBERS AND RATINGS
(Chemical Abstract Services)
(Standard Transportation Commodity Code)
(Registry of Toxic Effects of Chemical Substances)
(United Nations/North America)
(Chemical Hazard Response Information System)
(Resource Conservation and Recovery Act)
(U.S. Department of Transportation)
2.1, flammable gas
NFPA 704 Rating
(National Fire Protection Association)
(International Maritime Organization)
2.1, flammable gas
dimethylamine, anhydrous DMA
If containers of dimethylamine are threatened by the radiant heat of a distant fire, or if fire is approaching and flame impingement is possible, cool the containers by applying water from unmanned appliances placed as far away as possible. Note the amount of gas being vented by the safety relief device. If fire is close, the gas escaping from the container will be ignited. Never extinguish burning gas unless the supply of the gas can be stopped immediately following extinguishment. Any container of gas or liquefied gas is subject to a BLEVE (boiling-liquid, expanding-vapor explosion) if heated to the point at which the integrity of the container is breached or if the liquid is heated above its critical temperature.
Burning dimethylamine may be extinguished by the application of alcohol-type foam, carbon dioxide, dry chemical, or water spray, depending on such variables as the amount of material released, the weather, wind speed and direction, the terrain, whether or not the material is contained, and the amount of extinguishing agent available. Depending on the specific conditions of the release and the fire, you may decide to allow the fuel to burn itself out. Do not make such a decision without first consulting all the resources assembled by the community’s emergency response plan.
If attempting extinguishment, keep in mind that the material is a liquefied gas. This means that greater amounts of gas will be evolved after extinguishment than before, since the remaining liquid is hotter than it was before ignition. Devastating explosions are possible through reignition of the gas by metal or other materials heated to temperatures above the ignition temperature of dimethylamine or simply through the gas finding an existing ignition source.
If the liquid can be contained, you can add water directly to the dimethylamine to form a dilute solution. If enough water can be added (and contained), the solution may be cooled down to temperatures at which the evolution of gas is reduced significantly. Reignition is still a possibility once the fire is extinguished.
Fighting fires involving concentrated solutions of dimethylamine (25 to 40 percent) in water may not be as difficult as fighting fires involving the anhydrous gas, but such fires still arc dangerous and require following all the above warnings.
PROTECTIVE CLOTHING AND EQUIPMENT
Choose protective clothing and equipment that will prevent any contact of dimethylamine with the eyes or skin. Rubber gloves, aprons, and boots may offer some skin protection; wear splashproof chemical goggles to protect the eyes. You must use positivepressure, self-contained breathing apparatus for respiratory protection. One reference states that butyl rubber and neoprene total encapsulating suits will offer protection for a period exceeding eight hours, although another reference rates neoprene as fair/poor. Safety is a relative matter. Contact individual manufacturers of total encapsulating suits to determine the degree of safety offered by each recommended material. Consult the manufacturers of dimethylamine for their recommendations for protection.
Inhalation. Move the victim to fresh air and keep him calm and warm. If the victim’s breathing stops 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.
Eye contact. Flush the eyes immediately for at least 20 minutes, lifting the eyelids occasionally. Immediate medical attention is required.
Skin contact. Wash the affected body areas with large amounts of water. If irritation continues after washing, seek medical attention.
Ingestion. Ingestion of dimethylamine is unlikely. If the victim is conscious, make him immediately drink large quantities of water and induce vomiting. Never try to make an unconscious person vomit or drink anything. Seek immediate medical attention.