Hexaethyl tetraphosphate

Mixtures containing hexaethyl tetraphosphate are produced by heating diethyl ether and phosphorus pentoxide. The reaction entails cleavage of the C-O bond of the ether. The molecule contains three pyrophosphate 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 is miscible and soluble in water. It is also soluble in a large number of organic solvents but not simple hydrocarbons. Hexaethyl tetraphosphate does not noticeably corrode metals such as brass and iron. However, when a small amount of water is added to the chemical, it forms a strong acid and quickly corrodes galvanized iron and more slowly corrodes pure iron. Hexaethyl tetraphosphate diluted with 0.1% water has a pH of 2.5. ==Precautions and toxicity==

Hexaethyl tetraphosphate can give off fumes that are toxic or corrosive 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. The chemical's toxicity to insects is not affected by whether it is made by the Scrader process or the Woodstock process. It is also very toxic to humans. 100% of chrysanthemum 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% of helianthus aphids can be killed by an aqueous solution containing 0.05% each of hexaethyl tetraphosphate and sodium lauryl sulfate. 94% of pea aphids can be killed by exposure for 24 hours to an emulsion containing a concentration of 2.4% of the chemical. 90% of potato 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. It is considered less toxic than its analog TEPP: ==Production==

Hexaethyl tetraphosphate was first synthesised by the German chemist Gerhard Schrader, who reacted phosphorus oxychloride and triethyl 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. The Germans also made hexaethyl tetraphosphate by phosphorus oxychloride and ethyl alcohol. This reaction requires slightly lower pressure than the Schrader process. ==Applications==

Hexaethyl tetraphosphate is used as an insecticide, in particular, the insecticide Bladan. The Germans commonly used this chemical as an insecticide during World War II, when nicotine-based insecticides were not available. ==History==

Hexaethyl tetraphosphate was first described by Schrader in 1938. ==References==