CHEMICAL DATA NOTEBOOK SERIES #95: METHYL FORMATE
HAZARDOUS MATERIALS
Methyl formate is a flammable, toxic, irritating, somewhat corrosive liquid with a fruity or ether-like odor. It is used as a fumigant, refrigerant, and solvent and also in the manufacture of many chemicals, such as dyes, embalming fluids, pharmaceuticals, and poison gases (for military use).
Methyl formate belongs to a family of hydrocarbon derivatives called esters (hydrocarbon derivatives with the general formula R-C-O-O-R’, where Ris a hydrocarbon backbone or radical and -R’ may be the same or a different hydrocarbon backbone; R also may be a hydrogen atom). All esters have distinctive odors, and many (those that are not toxic) possess the flavors and fragrances of fruits and flowers. The short-chain esters have first names such as methyl, ethyl, propyl, butyl, and vinyl and last names such as formate, acetate, propionate, butyrate, and acrylate. Just as in other families of hydrocarbon derivatives, the short-chain compounds are flammable liquids, while the Ionger-chain members (in which the hydrocarbon portion usually is longer than five carbons) are combustible liquids. As the chain gets longer and the molecule gets bigger and heavier, the Ionger-chain compounds tend to become solid compounds (still retaining the property that allows them to burn).
PROPERTIES
Methyl formate has a flash point of — 32°F (some references list it as high as 1.4°F), an ignition temperature of 840°F, and an explosive range of from 4.5 to 23.0 percent in air. It has a specific gravity of 0.97, a molecular weight of 60, and a vapor density of 2.07. Its boiling point is 88.7°F, its freezing point is — 146°F, and it is moderately soluble in water. Its molecular formula is HCOOCH
HAZARDS
Methyl formate’s major hazard is as a flammable liquid. Its extremely low flash point of — 32°F means that at almost all ambient temperatures, it generates vapors sufficient to form an ignitable mixture with the air near the surface of the product. Even though the lower explosive limit (LEI.) of methyl formate is 4.5 percent (a relatively high LEI. for flammable liquids), the material is so volatile that it very rapidly evaporates and builds up to the lower explosive limit. Since the upper explosive limit (UEL) is so high (23.0 percent), it is relatively difficult to have a buildup of vapors in a too-rich environment (above the UEL). Therefore, when liquid is released, assume that the vapors generated by methyl formate will be within the explosive range and that the explosive range will spread to some distance beyond the point of release.
Methyl formate is moderately toxic. Its TI.V-TWA (threshold limit value-time weighted average as established by the American Conference of Governmental and Industrial Hygienists) is 10 ppm (parts per million of air). Its STEL (shortterm exposure limit) is 150 ppm. OSHA has established a PEL (permissible exposure limit) of 100 ppm.
Inhaling low concentrations of methyl formate irritates the eyes, nose, throat, and lungs. Higher concentrations can depress the central nervous system and cause convulsions, headache, nausea, pulmonary edema, vision problems, unconsciousness, and death.
Prolonged contact with the skin will irritate, crack, and dry it as a result of methyl formate’s solvent action on lat. (Methyl formate is not corrosive to skin.) The skin can absorb quantities of methyl formate sufficient to cause death, which will be preceded by the same symptoms caused by ingestion and inhalation. Ingesting large quantities of methyl formate can cause death. Ingesting lesser quantities can irritate the mouth, esophagus, and stomach (including severe gastric upset).
Although considered a stable chemical, methyl formate reacts with some chemicals in a violent manner. It may ignite violently or otherwise react strongly in the presence of strong oxidizing agents and will form an explosive compound when reacting with methyl alcohol and sodium methoxide. While it is not corrosive to most metals, it can corrode some rubber and plastic materials.
NONFIRE RELEASE
As you would in any other incident involving a release of flammable material, approach the incident scene from upwind and uphill. Eliminate all possible ignition sources and consider evacuation procedures for everyone in the possible danger area. Notify the proper environmental authorities. Under today’s laws, this is done by activating the community’s emergency response plan as dictated by the Superfund Amendments and Reauthorization Act (SARA ) of 1986. The assistance of these experts may prove invaluable to the incident commander, responders, and the environment.
Its vapor density of 2.07 (a little more than twice the density of air) allows methyl formate vapors released from a spill of liquid or an opening in the container to travel a great distance if not disturbed by a breeze because the vapors, which technically are fluids, flow along low spots in the ground seeking an igni– tion source.
Methyl formate’s ignition temperature is well within the reach of all common ignition sources. Therefore, any vapors within the explosive range will explode when ignited. The force of the explosion will be directly proportional to the amount of vapors available for ignition and position in the flammable range. Vapor concentrations that do not reach an ignition source and are present in a low spot or enclosed space can seriously or fatally injure anyone not wearing respiratory protection who enters the area.
Apply a high-pressure mist or fog immediately downwind of the leak to disperse vapors leaking from a container. Contain all runoff, which will contain some dissolved methyl formate. If liquid is leaking from the container, do not attempt to plug the leak until it has been determined that you can do it safely. Wooden plugs may be driven into a hole in the container if wooden or nonsparking tools are used.
The volatile nature of methyl formate causes very large volumes of explosive vapor to be generated once the liquid has been released. Again, applying high-pressure, finely divided water will help prevent vapor clouds from collecting and moving on a gentle breeze. Again, contain all runoff water and consider evacuating tor up to a mile around the release.
Contain all released liquid in as small an area as possible to keep contamination of the earth to a minimum and reduce the amount of vapor generated over a period of time. The smaller the surface area of the liquid, the less liquid exposed to the atmosphere and therefore the less vapor that will evaporate within a given period of time. If creating a containment pond by pushing up dirt around the release, the smaller the pond, the better.
Once the liquid is contained, professional salvage crews can attempt to salvage the material. In the meantime, cover the liquid with a compatible material or alcohol-type foam to slow the evolution of vapors. Adding water to the spilled product will dilute it. thus slowing the product’s evaporation. This action may damage the product beyond salvaging, but eliminating explosion hazards takes precedence over protecting the value of the spilled product. Professionals always must perform the salvage function, and environmental experts at the scene must determine the amount of earth that is contaminated and its proper disposition.
Do not allow the released methyl formate to enter sewers or waterways; the entry of such a volatile material into a sewer system could expose an entire community to an explosive hazard. It could be very dangerous to assume that the rapid evaporation of the product will fill up pipes to the point where the UEL is exceeded and the vapors cannot ignite. Methyl formate’s relatively high UEL means that there is an even greater chance of explosion with ignition than with other flammable liquids. The product spreads farther in the system, and an ignition and explosion danger exists at every opening (manholes and catch basins) along the system. The entire system could explode in a very short time. If, therefore, any product enters the system, eliminate ignition sources at all openings and immediately notify any sewage treatment facilities. Prevent initial entry by damming around openings and near any possible entry points into the waterway.
Methyl formate reaching a waterway will float on the surface while it begins to dissolve in the water. The speed of entering into solution depends on whether the water is moving, the amount of methyl formate involved, and the volume of water in the waterway. Again, notify at once all downstream users of the water, including industrial users, since they may be drawing water into their operations to cool equipment and processes. Water containing the dissolved product will release it immediately on being heated and can create an explosive atmosphere in a split second. Methyl formate can be removed from water by diverting the contaminated water into a holding area and aerating, sparging, or agitating (or some combination). The environmental experts will de£ cide when the water is safe for use.
FIRE SCENARIO
If a container of methyl formate is exposed to flames or radiant heat from a fire, the container can catastrophically fail as a result of pressure buildup caused by the rapid evolution of vapors within the container produced by the absorption of energy from the fire. This catastrophic failure will be evidenced by an explosion, a fireball produced by the released vapors as they are ignited, a rocketing container propelled by the released vapors, a trail of burning liquid (remember, it is not the liquid burning, but the vapors evaporated from the liquid), a concussion effect from the explosion, and shrapnel from the failed container. This sequence of events, also described as a BLEVE (boiling-liquid, expanding-vapor explosion), is behavior similar to that of other contained flammable liquids. The only difference is the damage done by different volumes of liquid in the containers. Other factors, such as the chemical makeup and volatility of the liquid, also produce some differences; the devastation from the explosion, however, might not seem that different. The point is that all flammable liquids in containers act the same way under similar conditions.
Protect containers holding methyl formate from heat exposure and the resulting rise in pressure by cooling with water from unmanned appliances placed as far away as possible. Safe distances depend on the size of the containers; allow a minimum of 3,500 feet when railcar tanks are involved. Firefighters must never let themselves get caught between a fire and containers of liquids or gases, whether flammable or not.
Extinguish burning methyl formate with a water spray or fog or alcohol-type foam. Water may be ineffective. You can use carbon dioxide or dry chemical if conditions such as the weather, volume of burning liquid, and amount of extinguisher available permit. Follow all rules for fighting flammable liquid fires. Be careful of vapor reignition caused by metal heated by the fire or the sudden appearance of other ignition sources. Follow all other standard operating procedures for handling flammable liquid fires.
Since methyl formate is moderately water-soluble, another mitigation technique that could be used is to add enough water to the contained product (in a nondisturbing fashion) to dilute and cool it to a point where the resulting solution has a very high flash point, in which case the fire would go out. Again, if using water, contain the runoff, since the resulting solution still contains acetone, which could produce another explosion and fire if released.
Once the fire is extinguished, be careful; reignition is a very real possibility. The low ignition temperature of methyl formate means that any piece of metal or other object heated to a temperature higher than 840°F will impart enough energy to ignite vapors within the explosive range.
IDENTIFICATION NUMBERS AND RATINGS
CAS
(Chemical Abstract Services)
107-31-3
STCC
(Standard Transportation Commodity’ Code)
4908225
KTECS
(Registry of Toxic Effects of Chemical Substances)
I.Q8925000
UN/NA
(United Nations/North America)
1243
CHRIS
(Chemical Hazard Response Information System) MFM
DOT
(U.S. Department of Transportation)
Class 3, flammable liquid
NFPA 704 Rating
2-4-0
IMO
(International Maritime Organization)
3.1. flammable liquid
SYNONYMS formic acid methyl ester methyl methanoate
PROTECTIVE CLOTHING AND EQUIPMENT
All responders who may come in contact with methyl formate must cover all skin and wear splashproof goggles and face shields. The use of impervious material is required if an encapsulating suit is used, always considering the solvent nature of methyl formate. Consult the list ol polymeric materials used by manufacturers to protect against specific chemicals and also perform tests to determine the actual degree of protection given by these materials. Protection is always relative and depends on factors such as the thickness of the polymeric material, the integrity of the seams, the concentration of the chemical. and the duration of the contact. Obtain samples of methyl formate and test small swatches of the suit material t onsuit with manufacturers of total encapsulating suits for recommendations with regard to the types of suits suitable for use with specific materials. The) will be happ to participate in these tests Also consult manufacturers of methyl formate.
FIRST AID
Inhalation. Administer artificial respiration and provide fresh air and immediate medical attention. Monitor the victim for the onset of delayed symptoms for a period of time.
Skin. Wash affected body areas with large amounts of soap and water. Any apparent irritation requires medical attention.
lives. Flush with water for 1 5 minutes, occasionally lifting the eyelids. Provide immediate medical attention.
Ingestion Have the victim drink a large amount of water, induce vomiting, and provide immediate medical attention Never force an unconscious person to vomit or drink anything. Reference resources always disagree on whether vomiting should be induced in a person who has ingested certain materials. First-aid providers should seek guidance in this matter.
