Tetraethyl pyrophosphate
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IUPAC name
tetraethyl diphosphate
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3D model (Jmol)
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| ChemSpider | |
| ECHA InfoCard | 100.003.179 |
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PubChem CID
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| Properties | |
| C8H20O7P2 | |
| Molar mass | 290.19 g·mol−1 |
| Appearance | colorless to amber liquid |
| Odor | faint, fruity |
| Density | 1.19 g/mL (20°C) |
| Melting point | 0 °C; 32 °F; 273 K |
| Boiling point | decomposes |
| miscible | |
| Vapor pressure | 0.0002 mmHg (20°C) |
| Hazards | |
| Lethal dose or concentration (LD, LC): | |
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LDLo (lowest published)
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0.5 mg/kg (rat, oral) 2.3 mg/kg (guinea pig, oral) 3 mg/kg (mouse, oral) |
| US health exposure limits (NIOSH): | |
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PEL (Permissible)
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TWA 0.05 mg/m3 [skin] |
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REL (Recommended)
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TWA 0.05 mg/m3 [skin] |
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IDLH (Immediate danger)
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5 mg/m3 |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |
Tetraethyl pyrophosphate, abbreviated TEPP, is an organophosphate compound, which is used as an insecticide. This compound is a clear, colorless liquid, which is soluble in water, but hydrolyzes rapidly. There are several mechanism by which TEPP can be synthesized and it was first synthesized by Philippe de Clermont and Muscovite Wladimir Moschnin in 1854. It is a toxic compound, due to its anticholinesterase activity, which not only applies to insects, but also to other animals. TEPP is metabolized with the assistance of many different enzymes en the metabolistes are excreted via the urine.
The first reported synthesis of tetraethyl pyrophosphate was in the year 1854. Muscovite Wladimir Moschnin and Philippe de Clermont were the first chemists who synthesized and reported the TEPP synthesis. At that time, both were working at Adolphe Wurtz' laboratory in Paris. The fact that nobody knew anything about the toxicity of TEPP at this time was evidenced by De Clermont himself, who reported that he had tasted the compound out of curiosity. He described the taste as being a viscous liquid with a burning taste and a peculiar odor ("un liquide visqueux d’une saveur brulante(et) d’une odeur particuliere"). Even though TEPP has repeatedly been synthesized by other chemists during the years that followed, not until the 1930s had any adverse effects been observed. Furthermore, Philippe de Clermont has never been reported ill by his family up to his passing at the age of 90. In the meantime, organophosphorus chemistry has really started developing with the help of A. W. von Hofmann, Carl Arnold August Michaelis and Alecsandr Erminingel'dovich Arbusow.
It was not until 1932 before the first adverse effects of compounds similar to TEPP had been recognized. Willy Lange and Gerda von Krueger were the first to report such effects, about which the following statement was published in their article (in German):
"Interestingly, we report the strong effect of monofluorophosphate phosphoric acid alkyl esters on the human organism. The vapor of these compounds have a pleasant odor and sharply aromatic. After only a few minutes of inhaling the vapor, there is a strong pressure on the larynx, associated with shortness of breath. Then comes decreased awareness, opacities, and dazzling phenomena causing painful sensitivity of the eye to light. Only after several hours is there relief from these phenomena. They are apparently not caused by acidic decomposition products of the ester, but they are probably due to the Dialkyl monofluorophosphates themselves. The effects are exerted by very small amounts. "
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