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| Discovery | |
|---|---|
| Discovered by | Gerhard Schrader Ambrose |
| Discovered in | 1938 |
| Chemical Characteristics | |
| Chemical Name | O-Isopropyl Methylphosphonofluoridate |
| Chemical Family | Fluorinated organophosphorous compound |
| Chemical Formula | CH3P(O)(F)OCH(CH3)2 |
| NFPA Rating |
|
| Airborne Exposure Limit | 0.0001 mg/m3 |
| Boiling Point | 158 °C |
| Freezing/Melting Point | -56 °C |
| Vapor Pressure | 2.9 at 25 °C |
| Vapor Density (Air=1) | 4.86 |
| Liquid Density | 1.0887 at 25 °C/1.102 at 20 °C |
| Solubility in Water | Complete |
| Specific Gravity | 1.0887 at 25 °C |
| Appearance and Color | Colorless liquid. Odorless in pure form. |
| Precursors | |
| Key precursors | methylphosphonyl difluoride methylphosphonyl dichloride diisopropyl methylphosphonochloridate |
| Precursors | Dimethyl methylphosphonate isopropyl methylphosphonate |
| Other chemicals | Trimethylphosphite phosphorus trichloride triisopropyl phosphite |
Sarin or GB (O-Isopropyl methylphosphonofluoridate) is an extrememly toxic substance that is one of the world's most dangerous weapons of war. As a chemical weapons, it is classified as a weapon of mass destruction by the United Nations according to UN Resolution 687, and its production and stockpiling was outlawed by the Chemical Weapons Convention of 1993.
Sarin is similar in structure and biological activity to some commonly used insecticides, such as Malathion7, and are similar in biological activity to carbamates used as insecticides, such as Sevin7, and used in medicine, such as Mestinon7, Neostigmine7, and Antilirium7.
At room temperature, sarin is a colourless, odorless liquid. Its relatively high vapor pressure means that it evaporates quickly (about 36 times as quickly as tabun, another common chemical nerve agent). Its vapor is also colorless and odorless. It can be made more persistent through the addition of certain oils or petroleum products.
Sarin can be used as a binary chemical weapon; its two precursors are methylphosphonyl difluoride and a mixture of isopropyl alcohol and isopropyl amine. The isopropyl amine binds the hydrogen fluoride generated during the chemical reaction.
Sarin has a relatively short shelf life, and will Iraqis destroyed 40 or more tons of sarin that had decomposed, and that some Iraqi sarin had a shelf life of only a few weeks owing mostly to impure precursors.
According to the CIA, nations such as Iraq have tried to overcome the problem of sarin's short self life in two ways:
Like other nerve agents, sarin attacks the nervous system of the human body.
When a functioning motor nerve is stimulated it releases the neurotransmitter acetylcholine in order to transmit the impulse to a muscle or organ. Once the impulse has sent, the enzyme acetylcholinesterase breaks down the acetylcholine in order to allow the muscle or organ to relax.
Sarin is an extremely potent organophosphorus compound that disrupts the nervous system by inhibiting the enzyme
acetylcholine esterase by forming a covalent bond with the site of the enzyme where acetylcholine normally undergoes hydrolysis. This allows acetylcholine to build up and continue to act so that any nerve impulses is, in effect, continually transmitted.
Initial symptoms following exposure to sarin (and other nerve agents) are a runny nose, tightness in the chest and dilation of the pupils. Soon after, the victim will then have difficulty breathing, and will experience nausea and drooling. As the victim continues to lose control of his or her bodily functions, he or she will involuntary vomit, defecate and urinate. This phase is followed by twitching and jerking, and ultimately the victim will become comatose and suffocate as a consequence of convulsive spasms.
Sarin is a highly volatile liquid, so that inhalation as well as absorption through the skin pose a great threat. Even vapour concentrations will immediately penetrate the skin. Death may follow in one minute after direct ingestion of extremely low concentrations (0.01 mg per kg of body weight or higher). People who did not accumulate a lethal dose but did not receive immediate appropriate medical treatment may suffer permanent neurological damage.
Even at very low concentrations, sarin can be fatal. Death may follow in one minute after direct ingestion of about 0.01 milligram per kilogram of body weight if an antidote is not quickly admisitered. It is estimated that sarin is more than 500 times as toxic as cyanide.
Sarin was discovered in 1938 in Wuppertal-Elberfeld in the Ruhr valley of Germany by two German scientists while attempting to create stronger pesticides; it is the most toxic of the three G-agents made by Germany. The compound, which followed the previous discovery of the nerve agent tabun, was named in honor of its discoverers: Gerhard Schrader, Ambros, Rudriger and Van der LINde.
In mid-1939, the formula for the agent was passed to the Chemical Warfare section of the German Army Weapons Office, which ordered that it be brought into mass production for wartime use.
A number of pilot plants were built, and a high-production facility was under construction (but was not finished) by the end of World War II. Estimates for total sarin production by Nazi Germany range from 500 kg to 10 tons.
Though sarin, tabun and soman were incorporated into artillery shells, Germany ultimately decided not to use nerve agents against Allied targets. German intelligence was unaware that the Allies had not developed similar compounds, and they were concerned that the Allies' ability to reach German targets would prove devastating in a chemical war. The reason to why this was done is given in Speer, who was strongly opposed to the introduction of tabun, flew Otto Ambros, I.G.'s authority on poison gas as well as synthetic rubber, to the meeting. Hitler asked Ambros, "What is the other side doing about poison gas?" Ambros explained that the enemy, because of its greater access to ethylene, probably had a greater capacity to produce mustard gas than Germany did. Hitler interrupted to explain that he was not referring to traditional poison gases: "I understand that the countries with petroleum are in a position to make more [mustard gas], but Germany has a special gas, tabun. In this we have a monopoly in Germany." He specifically wanted to know whether the enemy had access to such a gas and what it was doing in this area. To Hitler's disappointment Ambros replied, "I have justified reasons to assume that tabun, too, is known abroad. I know that tabun was publicized as early as 1902, that Sarin was patented, and that these substances appeared in patents. (...) Ambros was informing Hitler of an extraordinary fact about one of Germany's most secret weapons. The essential nature of tabun and sarin had already been disclosed in the technical journals as far back as 1902, and I.G. had patented both products in 1937 and 1938. Ambros then warned Hitler that if Germany used tabun, it must face the possibility that the Allies could produce this gas in much larger quantities. Upon receiving this discouraging report, Hitler abruptly left the meeting. The nerve gases would not be used, for the time being at least, although they would continue to be produced and tested.
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