Tabun (nerve agent)
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| IUPAC name (RS)-Ethyl N,N-Dimethylphosphoramidocyanidate | |
| Other names GA; Ethyl dimethylphosphoramidocyanidate; Dimethylaminoethoxy-cyanophosphine oxide; Dimethylamidoethoxyphosphoryl cyanide; Ethyl dimethylaminocyanophosphonate; Ethyl ester of dimethylphosphoroamidocyanidic acid; Ethyl phosphorodimethylamidocyanidate; Cyanodimethylaminoethoxyphosphine oxide; Dimethylaminoethodycyanophosphine oxide; EA-1205; TL-1578 | |
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| Properties | |
Chemical formula | C5H11N2O2P |
| Molar mass | 162.129 g·mol−1 |
| Appearance | Colorless to brown liquid |
| Density | 1.0887 g/cm3 at 25 °C 1.102 g/cm3 at 20 °C |
| Melting point | −50 °C (−58 °F; 223 K) |
| Boiling point | 247.5 °C (477.5 °F; 520.6 K) |
Solubility in water | 9.8 g/100 g at 25 °C 7.2 g/100 g at 20 °C |
| Vapor pressure | 0.07 mmHg (9 Pa) |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards | Highly toxic. Fires involving this chemical may result in the formation of hydrogen cyanide |
| NFPA 704 (fire diamond) |  4 2 1 |
| Flash point | 78 °C (172 °F; 351 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).  N verify (what is  Y N ?) Infobox references | |
Chemical compound
Tabun or GA is an extremely toxic synthetic organophosphorus compound.[1] It is classified as a nerve agent because it can fatally interfere with normal functioning of the mammalian nervous system. Its production is strictly controlled and stockpiling outlawed by the Chemical Weapons Convention of 1993. Tabun is the first of the G-series nerve agents along with GB (sarin), GD (soman) and GF (cyclosarin).
Physical Properties
Tabun is a clear, colorless, and tasteless liquid with a faint fruity odor, though less pure samples may appear brown.[2] It is a volatile chemical, although less so than either sarin or soman.[2]
Chemistry and Synthesis
Reactions
Tabun can be deactivated chemically using common oxidizing agents such as sodium hypochlorite.[3]
Historic synthesis
Tabun was made on an industrial scale by Germany during World War II, based on a process developed by Gerhard Schrader. In the chemical agent factory in Dyhernfurth an der Oder, codenamed "Hochwerk", at least 12,000 metric tons of this agent were manufactured between 1942 and 1945. The manufacturing process consisted of two steps (see below); after the reactions, the mixture (consisting of ~75% solvent, ~25% desired product, plus insoluble salts and reactants) was filtered and vacuum-distilled. This yielded a technical product consisting either of 95% or 80% tabun (then known as Tabun A or B, respectively,[inconsistent] the second a product later in the war).[4][verification needed][better source needed]
Modern synthesis
Effects of exposure
The symptoms of exposure include:[5][6][7] nervousness/restlessness, miosis (contraction of the pupil), rhinorrhea (runny nose), excessive salivation, dyspnea (difficulty in breathing due to bronchoconstriction/secretions), sweating, bradycardia (slow heartbeat), loss of consciousness, convulsions, flaccid paralysis, loss of bladder and bowel control, apnea (breathing stopped) and lung blisters. The symptoms of exposure are similar to those created by all nerve agents. Tabun is toxic even in minute doses. The number and severity of symptoms which appear vary according to the amount of the agent absorbed and rate of entry of it into the body. Very small skin dosages sometimes cause local sweating and tremors accompanied with characteristically constricted pupils with few other effects. Tabun is about half as toxic as sarin by inhalation, but in very low concentrations it is more irritating to the eyes than sarin. Tabun also breaks down slowly, which after repeated exposure can lead to build up in the body.[2]
The effects of tabun appear slowly when tabun is absorbed through the skin rather than inhaled. A victim may absorb a lethal dose quickly, although death may be delayed for one to two hours.[6] A person's clothing can release the toxic chemical for up to 30 minutes after exposure.[2] Inhaled lethal dosages kill in one to ten minutes, and liquid absorbed through the eyes kills almost as quickly. However, people who experience mild to moderate exposure to tabun can recover completely, if treated almost as soon as exposure occurs.[2] The median lethal dose (LD50) for tabun is about 400 mg-min/m3.[8]
The lethal dose for a man is about .01 mg/kg. The median lethal dose for respiration is 400 mg-minute/m3 for humans. Respiratory lethal doses can kill anytime from 1-10 minutes. When the liquid enters the eye, it also can kill just as quickly. When absorbed via the skin, death may occur in 1-2 minutes, or it can take up to 2 hours. [9]
Treatment for suspected tabun poisoning is often three injections of a nerve agent antidote, such as atropine.[7] Pralidoxime chloride (2-PAM Cl) also works as an antidote; however, it must be administered within minutes to a few hours following exposure to be effective.[10]
