Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in thermometers. In common usage, it is often referred to simply as alcohol.

Ethanol is abbreviated as EtOH, using the common organic chemistry notation of representing the ethyl group (C₂H₅) with Et. This designation is used both by EMS and Hospital ER staff when describing alcohol intoxication, and is found in most chemistry textbooks as well.

Ethanol is a straight-chain alcohol, and its molecular formula is C₂H₅OH. An alternative notation is CH₃-CH₂-OH, which indicates that the carbon of a methyl group (CH₃-) is attached to the carbon of a methylene group (-CH₂-), which is attached to the oxygen of a hydroxyl group (-OH).

Its empirical formula is C₂H₆O, making it an isomer of dimethyl ether.

Except for use of fire, the fermentation of sugar into ethanol is the earliest organic reaction known to humanity. The intoxicating effects of ethanol consumption have been known since ancient times. In modern times, ethanol intended for industrial use is also produced from by-products of petroleum refining.

Ethanol has widespread use as a solvent of substances intended for human contact or consumption, including scents, flavorings, colorings, and medicines. In chemistry, it is both an essential solvent and a feedstock for the synthesis of other products. It has a long history as a fuel for heat and light and also as a fuel for internal combustion engines.

History

Writings attributed to Jabir ibn Hayyan (721–815) mention the flammable vapors of boiled wine. Al-Kindi (801–873) unambiguously described the distillation of wine.

In 1796, Johann Tobias Lowitz obtained pure ethanol by filtering distilled ethanol through activated charcoal.

Antoine Lavoisier described ethanol as a compound of carbon, hydrogen, and oxygen, and in 1808 Nicolas-Théodore de Saussure determined ethanol's chemical formula. Fifty years later, Archibald Scott Couper published the structural formula of ethanol, which placed ethanol among the first chemical compounds to have their chemical structure determined.

Ethanol was first prepared synthetically in 1826 through the independent efforts of Henry Hennel in Great Britain and S.G. Sérullas in France. In 1828, Michael Faraday prepared ethanol by acid-catalyzed hydration of ethylene, a process similar to that which is used today for industrial ethanol synthesis.