ethanol, a member of a class of organiccompounds that are given the general namealcohols; its molecular formula is C₂H₅OH. Ethanol is an important industrial chemical; it is used as asolvent, in the synthesis of other organic chemicals, and as an additive to automotivegasoline (forming a mixture known as agasohol). Ethanol is also the intoxicating ingredient of manyalcoholic beverages such asbeer,wine, anddistilled spirits.

There are two main processes for the manufacture of ethanol: thefermentation of carbohydrates (the method used for alcoholic beverages) and thehydration ofethylene. Fermentation involves the transformation of carbohydrates to ethanol by growingyeast cells. The chief raw materials fermented for the production of industrial alcohol aresugar crops such as beets and sugarcane and grain crops such ascorn (maize). Hydration of ethylene is achieved by passing a mixture of ethylene and a large excess of steam at high temperature and pressure over an acidiccatalyst.

Ethanol produced either by fermentation or by synthesis is obtained as a dilute aqueous solution and must be concentrated by fractionaldistillation. Direct distillation can yield at best the constant-boiling-point mixture containing 95.6 percent by weight of ethanol. Dehydration of the constant-boiling-point mixture yields anhydrous, or absolute, alcohol. Ethanol intended for industrial use is usuallydenatured (rendered unfit to drink), typically withmethanol,benzene, orkerosene.

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Pure ethanol is a colourless flammable liquid (boiling point 78.5 °C [173.3 °F]) with an agreeableethereal odour and a burning taste. Ethanol istoxic, affecting thecentral nervous system. Moderate amounts relax the muscles and produce an apparent stimulating effect by depressing the inhibitory activities of the brain, but larger amounts impair coordination and judgment, finally producing coma and death. It is an addictive drug for some persons, leading to thediseasealcoholism.

Ethanol is converted in the body first toacetaldehydeand then tocarbon dioxide andwater, at the rate of about half a fluid ounce, or 15 ml, per hour; this quantity corresponds to a dietary intake of about 100 calories.