Everything about Diethyl Ether totally explained
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» This article is about the chemical compound. For other uses, see aether.
Diethyl ether, also known as
ether and
ethoxyethane, is a clear, colorless, and highly
flammable liquid with a low
boiling point and a characteristic smell. It is the most common member of a class of chemical compounds known generically as
ethers. It is an
isomer of
butanol. Diethyl ether has the formula CH
3-CH
2-O-CH
2-CH
3. It is used as a common
solvent and has been used as a general
anesthetic. Ether is sparingly
soluble in
water (6.9 g/100 ml).
History
Alchemist Raymundus Lullus is credited with discovering the compound in
1275 AD, although there's no contemporary evidence of this. It was first synthesized in
1540 by
Valerius Cordus, who called it "
oil of sweet vitriol" (
oleum dulcis vitrioli)—the name was due to the fact that it was originally discovered by distilling a mixture of
ethanol and
sulfuric acid (then known as oil of vitriol)—and noted some of its medicinal properties. At about the same time, Theophrastus Bombastus von Hohenheim, better known as
Paracelsus, discovered ether's
analgesic properties. The name
ether was given to the substance in
1730 by
August Siegmund Frobenius.
Metabolism
A putative
cytochrome P450 enzyme is believed to metabolize diethyl ether.
Diethyl ether inhibits
alcohol dehydrogenase, and thus slows down the metabolism of
ethanol. It also inhibits metabolism of other drugs requiring
oxidative metabolism.
Applications
Diethyl ether is a common laboratory
solvent. It has limited solubility in water, thus it's commonly used for
liquid-liquid extraction. Being less dense than water, the ether layer is usually on top. Its counterpart is
dichloromethane, which is similarly insoluble in water, and is also used for liquid-liquid extraction (dichloromethane is usually the lower phase). Diethyl ether is a common solvent for the
Grignard reaction, and for many other reactions involving organometallic reagents. It is particularly important as a solvent in the production of cellulose plastics such as
cellulose acetate. Diethyl ether has a high
cetane number of 85 - 96 and is used as a starting fluid for diesel and gasoline engines because of its high volatility and low
autoignition temperature.
Anesthetic use
The American doctor
Crawford Williamson Long, M.D., was the first surgeon to use it as a
general anesthetic, on March 30, 1842.
William T.G. Morton was previously credited with the first public demonstration of ether anesthesia on
October 16,
1846 at the
Ether Dome in
Boston, Massachusetts, although Dr.
Crawford Long is now known to have demonstrated its use publicly to other officials in Georgia. Ether was sometimes used in place of
chloroform because it had a higher
therapeutic index, a larger difference between the recommended dosage and a toxic overdose. Ether is still the preferred anesthetic in some
developing nations due to its high
therapeutic index (~1.5-2.2) and low price.
Because of its associations with Boston, the use of ether became known as the "Yankee Dodge."
Today, ether is rarely used. The use of flammable ether waned as nonflammable anesthetic agents such as
halothane became available. Additionally, ether had many undesirable side effects, such as postanesthetic nausea and vomiting. Modern anesthetic agents, such as
methyl propyl ether (Neothyl) and
methoxyflurane (Penthrane) reduce these side effects. Ether tends to be difficult to consume alone, and thus was often mixed with drugs like ethanol for recreational use. Ether may also be used as an
inhalant.
Due to its immiscibility with water and the fact that non-polar organic compounds are highly soluble in it, ether is also used in the production of
freebase cocaine, and is listed as a Table II precursor under the
United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances.
Production
Diethyl ether is rarely prepared in laboratories because of the hazards involved and the easy availability to legitimate labs. Most diethyl ether is produced as a byproduct of the vapor-phase
hydration of
ethylene to make
ethanol. This process uses solid-supported
phosphoric acid catalysts and can be adjusted to make more ether if the need arises. .
Diethyl ether can be prepared both in laboratories and on an industrial scale by the acid ether synthesis.
Ethanol is mixed with a strong acid, typically
sulfuric acid, H
2SO
4. The acid
dissociates producing
hydrogen ions, H
+. A hydrogen ion
protonates the
electronegative oxygen atom of the ethanol, giving the ethanol molecule a positive charge:
» CH
3CH
2OH + H
+ → CH
3CH
2OH
2+
A
nucleophilic oxygen atom of unprotonated ethanol
displaces a water molecule from the protonated (
electrophilic) ethanol molecule, producing water, a hydrogen ion and diethyl ether.
» CH
3CH
2OH
2+ + CH
3CH
2OH → H
2O + H
+ + CH
3CH
2OCH
2CH
3
This reaction must be carried out at temperatures lower than 150°C in order to ensure that an elimination product (
ethylene) isn't product of the reaction. At higher temperatures, ethanol will dehydrate to form ethylene. The reaction to make diethyl ether is reversible, so eventually an
equilibrium between reactants and products is achieved. Getting a good yield of ether requires that ether be distilled out of the reaction mixture before it reverts to ethanol, taking advantage of
Le Chatelier's principle.
Safety
Diethyl ether is prone to
peroxide formation, and can form explosive
diethyl ether peroxide. Ether peroxides are higher boiling and are contact explosives when dry. Diethyl ether is typically supplied with trace amounts of the
antioxidant BHT (2,6-di-tert-butyl-4-methylphenol), which reduces the formation of peroxides. Storage over NaOH precipitates the intermediate ether hydroperoxides. Water and peroxides can be removed by either distillation from
sodium and
benzophenone, or by passing through a column of
activated alumina.
Ether is an extremely flammable material. Open flames and even electrically heated devices should be avoided when using ether since it's easily ignited by a flame or spark. Ether's autoignition temperature is only 170°C (338°F), so it can be ignited by a hot surface without a flame or spark. The most common practice in chemical labs is to use steam (thus limiting the temperature to 100°C (212°F) when ether must be heated or distilled.
Cultural references
Recreational use of diethyl ether was portrayed in the film
Fear and Loathing in Las Vegas, based on the book of the same name by
Hunter S. Thompson, and portrayed in the novel
The Cider House Rules by
John Irving and in the film adaptation of the same name. An example of ether being used as a drug in the 19th century is to be found in
Italo Svevo's novel
Senilità (1898). One of the main characters, Amalia, a reticent spinster in her early thirties, has become addicted to ether, falls into delirium and dies. It is also mentioned in Raymond Chandler's novel "The Big Sleep", in which he describes one of the characters under the influence of it.
Further Information
Get more info on 'Diethyl Ether'.
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