 | |
| Names | |
|---|---|
| Preferred IUPAC name Hexaethyl tetraphosphate | |
| Other names HETP; ethyl tetraphosphate, hexa-; Bladan Base | |
| Identifiers | |
| |
3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.010.961 |
| UNII | |
| |
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| Properties | |
| C12H30P4O13 | |
| Molar mass | 506.25 g/mol |
| Appearance | yellow to brown liquid |
| Density | 1.331 g/cm3 |
| Melting point | −40 °C (−40 °F; 233 K) |
| Boiling point | 467.01 °C (872.62 °F; 740.16 K) |
| moderate | |
| Solubility | most organic solvents |
Refractive index (nD) | 1.443 |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards | skin absorption; inhalation |
| Flash point | 120.82 °C (249.48 °F; 393.97 K) |
| Related compounds | |
Related compounds | tetraethyl pyrophosphate pentaethyl triphosphate |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Hexaethyl tetraphosphate (also known asHETP) is theorganophosphorus compound with thechemical formula [(C2H5O)3P2O3]2O. The compound has not been isolated in pure form but appears to be a colorless liquid at room temperature. Commercial samples appear brown due to impurities.[1][2] It is a constituent of the insecticideBladan.[3] In the 1940s, it was about as significant an insecticide asDDT and was referred to as "another of DDT's rivals for fame" in a 1948 book.[4]
Mixtures containing hexaethyl tetraphosphate are produced by heatingdiethyl ether andphosphorus pentoxide. The reaction entails cleavage of the C-O bond of the ether.[5] The molecule contains threepyrophosphate bonds, which are the sites of high reactivity. The compound exists as two diastereomers, the meso- and dl-isomers.
Hexaethyl tetraphosphate does not burn readily. It ismiscible andsoluble in water.[6] It is also soluble in a large number oforganic solvents but not simple hydrocarbons.[1]Hydride reducing agents, convert it tophosphine, a toxic gas.[6] Hexaethyl tetraphosphate readilyhydrolyzes tonontoxic products.[1]
Since the material has not been obtained in pure form, the properties remain unverified.[3]
Hexaethyl tetraphosphate does not noticeablycorrode metals such asbrass andiron. However, when a small amount of water is added to the chemical, it forms astrong acid and quickly corrodesgalvanized iron and more slowly corrodes pure iron. Hexaethyl tetraphosphate diluted with 0.1% water has a pH of 2.5.[3]
Hexaethyl tetraphosphate can give off fumes that aretoxic orcorrosive if it is heated. Runoff containing the chemical can also lead to the pollution of waterways. Containers of it can also explode at high temperatures. If inhaled, swallowed, or absorbed via the skin, it can cause death.[6]Mites,aphids,thrips,leafhoppers, and some types ofcaterpillars are highly susceptible to being poisoned by hexaethyl tetraphosphate.[1][7] The chemical's toxicity to insects is not affected by whether it is made by the Scrader process or the Woodstock process.[8] It is also very toxic to humans.[3]
Out of 133 plant species that were tested for a reaction to hexaethyl tetraphosphate, only two types of plants were negatively affected. These werechrysanthemums andtomatoes.[3]
TheLD50 of hexaethyl tetraphosphate for thrips is 0.01%.[clarification needed] 99% of aphids can be killed by a concentration of 1 to 2.5 grams of a 10% solution of the chemical in a 1000cubic foot area. In one experiment, 100% ofmelon aphids were killed after exposure to anaqueous solution containing 0.025% hexaethyl tetraphosphate and 0.025%sodium lauryl sulfate. 99% of aphids can be killed by 0.3 grams of a 10% solution of the chemical inmethyl chloride in 1000 cubic feet, and 100% of aphids can be killed by twice the amount of solution. 96% ofapple aphids can be killed be exposure to an aqueous solution of 0.1% hexaethyl tetraphosphate and 0.05% sodium lauryl sulfate. Dust containing 3% hexaethyl tetraphosphate at a concentration of 40 pounds per acre can kill somebean aphids.[8] 100% ofcabbage aphids can be killed by an aqueous solution of 0.1% of the chemical and 0.05% sodium lauryl sulfate. Cabbage aphids can be quickly killed by a spray containing one pint of the chemical per 100 gallons of water.[9]
100% ofchrysanthemum aphids can be killed by an aqueous solution of 0.1% hexaethyl tetraphosphate and 0.05% sodium lauryl sulfate. 97% of chrysanthemum aphids can be killed by 3 grams of a 10% solution of the chemical in 1000 cubic feet. 100% ofhelianthus aphids can be killed by an aqueous solution containing 0.05% each of hexaethyl tetraphosphate and sodium lauryl sulfate. 94% ofpea aphids can be killed by exposure for 24 hours to anemulsion containing a concentration of 2.4% of the chemical. 90% ofpotato aphids can be killed by exposure for 42 hours to a one pint of a 50% solution of the chemical in 100 gallons of water.[9]
The effects of hexaethyl tetraphosphate on thecholinesterase ofrat andcockroachtissue have been tested.[10] It is considered less toxic than its analogTEPP:
| Animal | rabbit,i. v. | rat,oral | rat,i. p. | rat,s. c. | mouse, oral | mouse, i. p. |
|---|---|---|---|---|---|---|
| HETP | 0.69 | 7 | 2.5 | 0.64 | 56 | 6.1 |
| TEPP | 0.3 | 1.1 | 0.65 | 0.279 | 3 | 0.83 |
Hexaethyl tetraphosphate was first synthesised by the German chemistGerhard Schrader, who reactedphosphorus oxychloride andtriethyl orthophosphate at approximately 150 °C. This reaction is known as the Schrader process and was protected by a patent which Schrader filed in August 1938.[13] The Germans also made hexaethyl tetraphosphate by phosphorus oxychloride andethyl alcohol. This reaction requires slightly lowerpressure than the Schrader process.[1] The reaction has a chemical equation of POCl3 + 3(C2H5)3PO4 → (C2H5)6P4O13 + 3C2H5Cl.[7]
By 1947, hexaethyl tetraphosphate was being produced on a commercial scale. It cost US$1.10 per pound in the form ofdrums and $2.00 per pound in the form ofcarboys.[7] In the 1940s, the chemical was commercially produced at concentrations of 50%.[8]
Hexaethyl tetraphosphate's U.N. Shipping Number is 1611.[14]
Hexaethyl tetraphosphate is used as aninsecticide, in particular, the insecticide Bladan.[1] The Germans commonly used this chemical as an insecticide during World War II, whennicotine-based insecticides were not available.[1]
Hexaethyl tetraphosphate was first described by Schrader in 1938.[1][7] It was discovered during research onchemical warfare agents.[1] Americans first heard of the chemical after 1945, from two people named Hall and Kilgore. The United States began to produce the chemical in 1946.[7]
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