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Names | |
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Preferred IUPAC name Methyl fluoroacetate | |
Other names
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Identifiers | |
3D model (JSmol) | |
ChemSpider | |
ECHA InfoCard | 100.006.563 |
EC Number |
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PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
FCH2CO2CH3 | |
Molar mass | 92.069 g·mol−1 |
Appearance | Colorless liquid |
Odor | Odorless or faint fruity |
Melting point | −40 °C (−40 °F; 233 K) |
Boiling point | 104 °C (219 °F; 377 K) |
117 g/L at 25 °C | |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards | Extremely toxic |
GHS labelling: | |
Danger | |
H226, H300, H315, H319, H335, H400 | |
P210, P233, P240, P241, P242, P243, P261, P264, P270, P271, P273, P280, P301+P310, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P370+P378, P391, P403+P233, P403+P235, P405, P501 | |
Flash point | −32 °C (−26 °F; 241 K) |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 6 mg/kg (mice) |
Related compounds | |
Related compounds | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Methyl fluoroacetate (MFA) is an organic compound with the chemical formula F C H 2CO 2CH3. It is an extremely toxic methyl ester of fluoroacetic acid. It is a colorless, odorless liquid at room temperature. It is used as a laboratory chemical and as a rodenticide. Because of its extreme toxicity, MFA was studied for potential use as a chemical weapon. [1]
The general population is not likely to be exposed to methyl fluoroacetate. People who use MFA for work, however, can breathe in or have direct skin contact with the substance. [2]
MFA was first synthesized in 1896 by the Belgian chemist Frédéric Swarts by reacting methyl iodoacetate with silver fluoride. It can also be synthesized by reacting methyl chloroacetate with potassium fluoride [1]
Because of its toxicity, MFA was studied for potential use as a chemical weapon during World War II. It was considered a good water poison since it is colorless and odorless and therefore it can toxify the water supply and kill a big part of the population. By the end of the war, several countries began to make methyl fluoroacetate to debilitate or kill the enemy. [2]
The synthesis of methyl fluoroacetate consists of a two-step process: [3]
Methyl fluoroacetate is a methyl ester of fluoroacetic acid.
MFA is a liquid, which is odorless or can have a faint, fruity smell. The boiling point of MFA is 104.5 °C and the melting point is −35.0 °C. It is soluble in water (117 g/L at 25 °C) and slightly soluble in petroleum ether. [2]
MFA is resistant to the displacement of fluorine by nucleophiles, so there is higher stability of the C−F bond compared to the other halogens (C−Cl , C−Br , C−I ). The other haloacetates are more powerful alkylating agents that react with −SH group of proteins. This, however, does not happen for MFA and gives it a unique toxic action. [2] Moreover, MFA is a derivative of fluoroacetate (FA) compound which is as toxic and has similar biotransformation to MFA.
Generally, fluoroacetates are toxic because they are converted to fluorocitrate by fluoroacetyl coenzyme A. Fluorocitrate can inhibit aconitate hydratase, which is needed for the conversion of citrate, by competitive inhibition. [4] This interrupts the citric acid cycle (TCA cycle) and also causes citrate to accumulate in the tissues and eventually in the plasma.[ clarification needed ] MFA is mainly biotransformed by glutathione transferase enzyme in a phase 2 biotransformation process. The GSH-dependent enzyme couples glutathione to MFA and thereby defluorinating MFA.[ clarification needed ] As a result, a fluoride anion and S-carboxymethylglutathione are produced. The decoupling of fluoride is mediated by a fluoroacetate-specific defluorinase.[ clarification needed ] The defluorinating activity is mainly present in the liver, but also kidneys, lungs, the heart, and the testicles show activity. In the brain, there are no signs of defluorination. Eventually, fluorocitrate (FC) is formed which is the main toxic compound. It binds the aconitase enzyme with a very high affinity and therefore intervenes in the TCA cycle. Citrate in normal circumstances is converted to succinate, but the process is inhibited. The cycle stops and oxidative phosphorylation is prevented since NADH, FADH2 and succinate are required from the TCA cycle. Respiration stops shortly. The poison acts very quickly and has no antidote.
Mammals are intolerant to MFA. However, a few Australian species (e.g. brush-tailed possum) show a level of tolerance to fluoroacetate by metabolizing it using glutathione-S-transferase. [5] Fluoride can be removed from fluoroacetate or fluorocitrate. It is involved in detoxifying the aryl and alkyl groups by converting them into glutathione conjugates. The C−F bond is cleaved because of a nucleophilic attack of carbon resulting in the formation of S-carboxymethyl glutathione. This can be afterward excreted in the form of S-carboxymethylcysteine. [5]
The elimination half-life of biotransformed MFA is about 2 days. When administered, the MFA mainly resides in blood plasma, but can also be traced in the liver, kidney, and muscle tissue. [6]
MFA is a convulsant poison. It causes severe convulsions in poisoned victims. [7] Death results from respiratory failure. [6]
For a variety of animals, the toxicity of methyl fluoroacetate has been determined orally and through subcutaneous injection. The dosage ranges from 0.1 mg/kg in dogs to 10–12 mg/kg in monkeys indicating considerable variation. An order of decreasing susceptibility has been determined within these animals which is: dog, guinea-pig, cat, rabbit, goat, and then likely horse, rat, mouse, and monkey. For the rat and mouse, the toxicity by inhalation has been investigated more fully than for other animals. The LD50 for the rat and mouse are 450 mg/m3 and above 1,000 mg/m3 for 5 minutes, respectively. In dogs, guinea-pigs, cats, rabbits, goats, horses, rats, mice, and monkeys, the pharmacological effects of this substance have been investigated by mouth and by injection. Methyl fluoroacetate causes progressive depression of respiration and is a convulsant poison in most animals. When applied to the skin it is not toxic, yet through inhalation, injection and by mouth it is. For the rat, cat and the rhesus monkey, the effects of methyl fluoroacetate have been determined similar to those of nicotine, strychnine, leptazol, picrotoxin, and electrically induced convulsions. The convulsive pattern is considered to be similar to that of leptazol. Little besides signs of asphyxia is found post-mortem in these animals. Estimations have been made for blood sugar, hemoglobin, plasma proteins, non-protein nitrogen, and serum potassium, calcium, chloride, and inorganic phosphate in a small number of rabbits, dogs, and goats. Blood changes include a rise of 20 to 60% in hemoglobin, a rise of up to 90% in blood sugar, a rise of 70 to 130% in inorganic phosphate, and a less significant rise in serum potassium with a terminal rise in non-protein nitrogen and potassium. The whole central nervous system is affected by methyl fluoroacetate just like with leptazol, with the higher centers being more sensitive than the lower ones. Small doses of methyl fluoroacetate have little effect on blood pressure yet in large doses it has an action similar to nicotine. It further stimulates the rate and volume of respiration and then causes failure of the respiration, probably central in origin as seen through graphic records. The knee jerk reaction appears to be accentuated through methyl fluoroacetate until convulsions occur due to the irradiation of the stimuli being so facilitated. Nervous conduction is increased and the threshold stimulus lessened in the reflex arc of a spinal cat. Methyl fluoroacetate reduces the electric convulsive threshold about 10 times in rats. The difficulties of treatments are stressed as methyl fluoroacetate is both a powerful convulsant and a respiratory depressant, yet suggestions for treatment in man are made. Methyl fluoroacetate presents a serious hazard as a food and water contaminant in the case that it is used as a poison against rodents and other vermin, as it is not easily detected or destroyed and is equally toxic by mouth and by injection. [6]
Methyl fluoroacetate is produced and used as a chemical reagent and it can be released to the environment through several waste streams. When it was used as a rodenticide, it was released directly to the environment where it would be broken down in the air. If released to air, an estimated vapor pressure of 31 mmHg at 25 °C indicates methyl fluoroacetate will exist solely as a vapor in the atmosphere. [2] Vapor-phase methyl fluoroacetate will be degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals. The half-life for this reaction in air is estimated to be 98 days.
MFA does not contain chromophores that absorb at wavelengths > 290 nm and therefore it's not expected to be susceptible to direct photolysis by sunlight. [2]
The effects on animals occur very rapidly and strongly, all resulting in death. Exposure to a high concentration of MFA vapor does not show any symptoms in animals until 30–60 minutes. [6] Then violent reactions and death took place in a few hours, according to studies. From intravenous injection mice, rats, and guinea pigs show symptoms after 15 min to 2 hours. The animals become quiet and limp. Rabbits show a similar latent time period and muscle weakness. [6] Dogs show symptoms of hyperactivity. They are more sensitive because of higher rates of metabolism and, eventually, they also fail to respirate. Fish are more resistant because of slow metabolism [4] and therefore it is not expected that the substance will build up in fish. Also, Australian herbivores (e.g. possum and seed-eating birds) that live in a habitat consisting of plants with traces of fluoroacetate, have some tolerance. This can happen by detoxifying fluoroacetate or more resistivity of aconitase to fluorocitrate in the presence of GSH. Some insects can store the toxin in vacuoles and use it later. [4] The highly hazardous MFA cannot be used for poisoning animals without risking human life.
There is no known antidote against MFA, but there are some suggestions regarding the treatment of MFA poisoning. Advised is to use an intravenous injection of fast-acting anesthetics directly after poisoning. The anesthetic should be pentothal sodium or evipan sodium followed by an intramuscular injection of long-acting cortical depressants like sodium phenobarbitone or rectal avertin. Afterward, careful supervision of oxygen supply is necessary together with a BLB mask[ clarification needed ] and the use of artificial respiration. Possibly, the use of hypertonic glucose intravenously is required as in status epilepticus. At last, careful use of tubocurarine chloride should be applied to control any convulsions. [6] If any vomiting occurs, lean the patient forward to maintain an open airway.
Alternatively, there is a therapy aimed at the prevention of fluorocitrate synthesis, the blocking of aconitase within the mitochondria, and to provide a citrate outflow from the mitochondria to keep the TCA cycle going. For now, ethanol has proven to be the most effective against FC formation. When ethanol is oxidized, it increases blood acetate levels which inhibits FC production. In humans, an oral dose of 40-60 mL 96% ethanol is advised followed by 1.0-1.5 g/kg of 5-10% ethanol intravenously during the first hour and 0.1 g/kg during the following 6–8 hours. This therapy is meant for fluoroacetate (FA) poisoning which is highly related MFA, so this therapy aimed at MFA may result in other outcomes. [8]
Treatment with monoacetin (glycerol monoacetate) helped against FA poisoning. It aids in increasing acetate levels of the blood and it decreases citrate levels in the heart, brain, and kidneys. However, this is only tested experimentally. In monkeys, monoacetin even reverses the effects of FA: all biological effects normalized. [8] As with ethanol, monoacetin is effective against FA poisoning.
There is up until now, no proven treatment against MFA. However, the beforementioned treatments can provide starting points for therapy aimed at MFA since FA and MFA are closely related compounds. [8]
Potassium chloride is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt-like taste. Potassium chloride can be obtained from ancient dried lake deposits. KCl is used as a fertilizer, in medicine, in scientific applications, domestic water softeners, and in food processing, where it may be known as E number additive E508.
Potassium cyanide is a compound with the formula KCN. It is a colorless salt, similar in appearance to sugar, that is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications include jewellery for chemical gilding and buffing. Potassium cyanide is highly toxic, and a dose of 200 to 300 milligrams will kill nearly any human.
Sodium fluoroacetate, also known as compound 1080, is an organofluorine chemical compound with the chemical formula FCH2CO2Na. It is the sodium salt of fluoroacetic acid. It contains sodium cations Na+ and fluoroacetate anions FCH2CO−2. This colourless salt has a taste similar to that of table salt and is used as a rodenticide.
Aconitase is an enzyme that catalyses the stereo-specific isomerization of citrate to isocitrate via cis-aconitate in the tricarboxylic acid cycle, a non-redox-active process.
Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one hydrogen atom by an atom of iodine. It is naturally emitted by rice plantations in small amounts. It is also produced in vast quantities estimated to be greater than 214,000 tons annually by algae and kelp in the world's temperate oceans, and in lesser amounts on land by terrestrial fungi and bacteria. It is used in organic synthesis as a source of methyl groups.
An analeptic, in medicine, is a central nervous system stimulant. The term "analeptic" typically refers to respiratory stimulants. Analeptics are central nervous system (CNS) stimulants that include a wide variety of medications used to treat depression, attention deficit hyperactivity disorder (ADHD), and respiratory depression. Analeptics can also be used as convulsants, with low doses causing patients to experience heightened awareness, restlessness, and rapid breathing. The primary medical use of these drugs is as an anesthetic recovery tool or to treat emergency respiratory depression. Other drugs of this category are prethcamide, pentylenetetrazole, and nikethamide. Nikethamide is now withdrawn due to risk of convulsions. Analeptics have recently been used to better understand the treatment of a barbiturate overdose. Through the use of agents, researchers were able to treat obtundation and respiratory depression.
Chromyl chloride is an inorganic compound with the formula CrO2Cl2. It is a reddish brown compound that is a volatile liquid at room temperature, which is unusual for transition metal compounds.
This is the list of extremely hazardous substances defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act. The list can be found as an appendix to 40 CFR 355. Updates as of 2006 can be seen on the Federal Register, 71 FR 47121.
Azinphos-methyl (Guthion) is a broad spectrum organophosphate insecticide manufactured by Bayer CropScience, Gowan Co., and Makhteshim Agan. Like other pesticides in this class, it owes its insecticidal properties to the fact that it is an acetylcholinesterase inhibitor. It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act, and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.
Organofluorine chemistry describes the chemistry of organofluorine compounds, organic compounds that contain a carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, refrigerants, and reagents in catalysis. In addition to these applications, some organofluorine compounds are pollutants because of their contributions to ozone depletion, global warming, bioaccumulation, and toxicity. The area of organofluorine chemistry often requires special techniques associated with the handling of fluorinating agents.
Pumiliotoxin 251D is a toxic organic compound. It is found in the skin of poison frogs from the genera Dendrobates, Epipedobates, Minyobates, and Phyllobates and toads from the genus Melanophryniscus. Its name comes from the pumiliotoxin family (PTXs) and its molecular mass of 251 daltons. When the toxin enters the bloodstream through cuts in the skin or by ingestion, it can cause hyperactivity, convulsions, cardiac arrest and ultimately death. It is especially toxic to arthropods, even at low concentrations.
Dichapetalum cymosum, commonly known as gifblaar from Afrikaans, or occasionally by its English translation, poison leaf, is a small prostrate shrub occurring in northern parts of Southern Africa in the family Dichapetalaceae. It is notable as a common cause of lethal cattle poisoning in this region and is considered one of the 'big 6' toxic plants of cattle in South Africa. A 1996 estimate of plant poisonings in South Africa attributes 8% of cattle mortality caused by poisonous plants to it. The majority (70%) of fatal cases are in Limpopo province, with 10% each in North West, Mpumalanga, and Gauteng. Fluoroacetate, the poison used to synthetically produce Compound 1080 used extensively in New Zealand, occurs in all parts of the plant and is responsible for the toxic effects shown.
In chemistry, the haloform reaction is a chemical reaction in which a haloform is produced by the exhaustive halogenation of an acetyl group, in the presence of a base. The reaction can be used to transform acetyl groups into carboxyl groups or to produce chloroform, bromoform, or iodoform. Note that fluoroform can't be prepared in this way.
A convulsant is a drug which induces convulsions and/or epileptic seizures, the opposite of an anticonvulsant. These drugs generally act as stimulants at low doses, but are not used for this purpose due to the risk of convulsions and consequent excitotoxicity. Most convulsants are antagonists at either the GABAA or glycine receptors, or ionotropic glutamate receptor agonists. Many other drugs may cause convulsions as a side effect at high doses but only drugs whose primary action is to cause convulsions are known as convulsants. Nerve agents such as sarin, which were developed as chemical weapons, produce convulsions as a major part of their toxidrome, but also produce a number of other effects in the body and are usually classified separately. Dieldrin which was developed as an insecticide blocks chloride influx into the neurons causing hyperexcitability of the CNS and convulsions. The Irwin observation test and other studies that record clinical signs are used to test the potential for a drug to induce convulsions. Camphor, and other terpenes given to children with colds can act as convulsants in children who have had febrile seizures.
Chlorethoxyfos is an organophosphate acetylcholinesterase inhibitor used as an insecticide. It is registered for the control of corn rootworms, wireworms, cutworms, seed corn maggot, white grubs and symphylans on corn. The insecticide is sold under the trade name Fortress by E.I. du Pont de Nemours & Company.
2-Fluoroethanol is the organic compound with the formula CH2FCH2OH. This colorless liquid is one of the simplest stable fluorinated alcohols. It was once used as a pesticide. The related difluoro- and trifluoroethanols are far less dangerous.
Fluorocitric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)(CHFCO2H). It is a fluorinated carboxylic acid derived from citric acid by substitution of one methylene hydrogen by a fluorine atom. The appropriate anion is called fluorocitrate. Fluorocitrate is formed in two steps from fluoroacetate. Fluoroacetate is first converted to fluoroacetyl-CoA by acetyl-CoA synthetase in the mitochondria. Then fluoroacetyl-CoA condenses with oxaloacetate to form fluorocitrate. This step is catalyzed by citrate synthase. Flurocitrate is a metabolite of fluoroacetic acid and is very toxic because it is not processable using aconitase in the citrate cycle. The enzyme is inhibited and the cycle stops working.
Fluorine may interact with biological systems in the form of fluorine-containing compounds. Though elemental fluorine (F2) is very rare in everyday life, fluorine-containing compounds such as fluorite occur naturally as minerals. Naturally occurring organofluorine compounds are extremely rare. Man-made fluoride compounds are common and are used in medicines, pesticides, and materials. Twenty percent of all commercialized pharmaceuticals contain fluorine, including Lipitor and Prozac. In many contexts, fluorine-containing compounds are harmless or even beneficial to living organisms; in others, they are toxic.
Bis(trifluoromethyl)peroxide (BTP) is a fluorocarbon derivative first produced by Frédéric Swarts. It has some utility as a radical initiator for polymerisation reactions. BTP is unusual in the fact that, unlike many peroxides, it is a gas, is non-explosive, and has good thermal stability.
IPTBO is a bicyclic phosphate convulsant. It is an extremely potent GABA receptor antagonist that can cause violent convulsions in mice.