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 CH3-CH2-O-CH2-CH3. 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).
Alchemist Raymundus Lullus is credited with discovering the compound in 1275 AD, although there is 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 because 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.
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 may be used to anesthetize ticks before removing them from an animal or a person's body. The anesthesia relaxes the tick and prevents it from maintaining its mouthpart under the skin.
The anesthetic effects of ether have made it a recreational drug, although not a popular one. Diethyl ether is not as toxic as other solvents used as recreational drugs.
Ether, mixed with ethanol, was marketed in the 19th century as a cure-all and recreational drug, during one of Western society's temperance movements. At the time, it was considered improper for women to consume alcoholic beverages at social functions, and sometimes ether-containing drugs would be consumed instead. A cough medicine called Hoffmann's Drops was marketed at the time as one of these drugs, and contained both ether and alcohol in its capsules. 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.
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, H2SO4. 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:
This reaction must be carried out at temperatures lower than 150°C in order to ensure that an elimination product (ethylene) is not 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.
Another reaction that can be used for the preparation of ethers is the Williamson ether synthesis, in which an alkoxide (produced by dissolving an alkali metal in the alcohol to be used) performs a nucleophilic substitution upon an alkyl halide.
Ether is an extremely flammable material. Open flames and even electrically heated devices should be avoided when using ether since it is easily ignited by a flame or spark. The autoignition temperature of ether 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.
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.
In the television series M*A*S*H, ether is occasionally used as anesthesia for patients being treated.