See also: Glycol
The ethylene glycol or glycol or éthan-1,2-diol is the simplest chemical compound of the family of the Glycols.
Its Chemical formula is (it is simplest of the Diol S). The ethylene glycol is frequently employed as a Antigel, in the liquid of cooling of the Automobile S. With room temperature, it is a colorless viscous liquid and without odor, with a sweetened taste. The ethylene glycol is toxic, and its ingestion requires urgent medical care.
History
The ethylene glycol was synthesized for the first time in 1859 by the French chemist Charles-Adolphe Wurtz. It was produced in minor amount during the First World War like cooling agent and as component of Explosif S. Its industrial production began in 1937, since its precursor, the Oxyde of ethylene, itself was produced in industrial quantity at low prices.
It caused a small revolution in the world of the Aéronautique by replacing the Eau cooling system. Its high boiling point thus made it possible to decrease the size of the radiator, and thus its weight. Before the ethylene glycol is not available, the cooling systems indeed used water with high Pression; these systems cumbersome and not very reliable, and in the event of aerial combat, were easily touched by the enemy balls.
Production
It is synthesized starting from ethylene, via an intermediary of Oxyde of ethylene which reacts with the Eau, according to the equation:
This reaction can be catalyzed in medium basic Acide or , or even at high temperature. In acid medium and with a water excess, the output of the reaction can reach 90%. The Oligomère S of ethylene glycol (Diéthylène glycol, Triéthylène glycol, Tétraéthylène glycol) can be obtained same manner.
Use
Organic chemistry
It is used for the protection of the functions Carbonyle S, in the reaction of acetalisation.
General information
The ethylene glycol is especially employed as an antifreeze and a cooling agent. Its melting point being low, it was also used like de-icing for the windshields and the reaction engine . The ethylene glycol definitively took importance in the field of the petrochemical industres , where it allows the production of fibers and resins of Polyester S, of which the Polyéthylène terephthalate, principal material of the Bouteille S out of plastic. Its properties antifreeze make of it also an important component of the solutions intended for the organic fabric conservation at low temperature.
The temperature of high evaporation of the ethylene glycol and its great affinity for water make of it an ideal dessicant for the production of Natural gas. In the turns of separation, one thus makes meet the liquid ethylene glycol running top of the tower with the mixture of water and Hydrocarbure S gas escaping from bottom. The glycol collects water and runs out at the bottom, while the hydrocarbon vapors are recovered at the top. One reinjects then the ethylene glycol to renew the operation.
The ethylene glycol is also used in the manufacture of Vaccin S, although it is not present in the composition of the latter.
It is used as thickener in the Chinese toothpastes, and was used like excipient in a Chinese cough mixture exported in Panama.
Safety
Danger of ingestion
The principal danger of the ethylene glycol comes from its toxicity in the event of ingestion. Because of its sweetened taste, the children and the animals can introduce a great quantity of ethylene glycol if one leaves it with their range. The progression of the symptoms of a Intoxication with the ethylene glycol is done in three stages. The first stage is the apparation of neurological symptoms. The victim can appear slightly poisoned, complain about dizzy spell S and to have the confused air. Then, the body converts the ethylene glycol into another toxin, the Oxalic acid . It results from it from the Tachycardie and a Respiration jerked. The third stage is the development of a acute Impaired renal function.
Amounts of ethylene glycol of 30 ml (2 spoons with soup) can be mortals for adults. In all the cases, urgent medical care is necessary.
If the victim is still conscious, it is necessary to make it vomit, and if possible (reserved with the adults.) he to make drink 100 ml (small glass) of a strong alcohol with 45°. The ethanol replaces indeed the ethylene glycol near the Enzyme S which degrade this last into made up more toxic, which limits the production of toxins (one speaks about competitive inhibiter). It is also advisable to bring the person in a hospital where one will be able to manage to him, rather than ethanol, other inhibiters of alcohol déshydrogénase, enzyme responsible at the man for the transformation of ethanol into éthanal, and the ethylene glycol in oxalic Aldéhyde, which will be transformed (thanks to others déshydrogénases) finally into oxalate, which is toxic for him.
Because of its toxicity, the ethylene glycol already made speak about him in the media:
- In 1996, sixty children with Haiti died of one intoxication to the ethylene glycol which was in Sirop against the Toux.
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In 2007 one discovered glycol in toothpastes coming from China. Manufacturing which agreed to answer journalist explained that the glycol makes it possible the paste to have good consistency. In theory one does not swallow a toothpaste by washing the teeth, but in practice that can arrive very well, especially with regard to the children.
Inflammability
Not very flammable in the liquid state, the ethylene glycol can be explosive in a gas state (see example celebrates hereafter). It is thus essential to handle it in quite ventilated buildings (concentration lower than 100 mg/m ³).
The electrolysis of the ethylene glycol with a Anode silver produces a reaction Exothermique. The fire of Apollo 1 is due to this reaction; indeed, the ethylene glycol, mixed with water was used like fuel for low Pression.
Precautions
The ethylene glycol vapors are irritating before being dangerous. The chronic exposure is however the source of recognized pathologies, in France, like occupational diseases by the code of the Social security.
To consult the toxicological card of ethylene glycol by INRS.
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