ethanol

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ethanol

(ĕth`ənōl') or

ethyl alcohol,

CH3CH2OH, a colorless liquid with characteristic odor and taste; commonly called grain alcohol or simply alcoholalcohol,
any of a class of organic compounds with the general formula R-OH, where R represents an alkyl group made up of carbon and hydrogen in various proportions and -OH represents one or more hydroxyl groups.
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.

Properties

Ethanol is a monohydric primary alcohol. It melts at −117.3°C; and boils at 78.5°C;. It is miscible (i.e., mixes without separation) with water in all proportions and is separated from water only with difficulty; ethanol that is completely free of water is called absolute ethanol. Ethanol forms a constant-boiling mixture, or azeotrope, with water that contains 95% ethanol and 5% water and that boils at 78.15°C;; since the boiling point of this binary azeotrope is below that of pure ethanol, absolute ethanol cannot be obtained by simple distillation. However, if benzene is added to 95% ethanol, a ternary azeotrope of benzene, ethanol, and water, with boiling point 64.9°C;, can form; since the proportion of water to ethanol in this azeotrope is greater than that in 95% ethanol, the water can be removed from 95% ethanol by adding benzene and distilling off this azeotrope. Because small amounts of benzene may remain, absolute ethanol prepared by this process is poisonous.

Ethanol burns in air with a blue flame, forming carbon dioxide and water. It reacts with active metals to form the metal ethoxide and hydrogen, e.g., with sodium it forms sodium ethoxide. It reacts with certain acids to form esters, e.g., with acetic acid it forms ethyl acetate. It can be oxidized to form acetic acid and acetaldehyde. It can be dehydrated to form diethyl ether or, at higher temperatures, ethylene.

Preparation

Ethanol is the alcohol of beer, wines, and liquors. It can be prepared by the fermentation of sugar (e.g., from molasses), which requires an enzyme catalyst that is present in yeast; or it can be prepared by the fermentation of starch (e.g., from corn, rice, rye, or potatoes), which requires, in addition to the yeast enzyme, an enzyme present in an extract of malt. The concentration of ethanol obtained by fermentation is limited to about 10% (20 proof) since at higher concentrations ethanol inhibits the catalytic effect of the yeast enzyme. (The proof concentration of an alcoholic beverage is numerically double the percentage concentration.) For nonbeverage uses ethanol is more commonly prepared by passing ethylene gas at high pressure into concentrated sulfuric or phosphoric acid to form the corresponding ester; the acid-ester mixture is diluted with water and heated, forming ethanol by hydrolysis, and the alcohol is then removed from the mixture by distillation, usually with steam.

Uses

Ethanol is used extensively as a solvent in the manufacture of varnishes and perfumes; as a preservative for biological specimens; in the preparation of essences and flavorings; in many medicines and drugs; as a disinfectant and in tinctures (e.g., tincture of iodine); and as a fuel and gasoline additive (see gasoholgasohol,
a gasoline extender made from a mixture of gasoline (90%) and ethanol (10%; often obtained by fermenting agricultural crops or crop wastes) or gasoline (97%) and methanol, or wood alcohol (3%).
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). Many U.S. automobiles manufactured since 1998 have been equipped to enable them to run on either gasoline or E85, a mixture of 85% ethanol and 15% gasoline. E85, however, is not yet widely available. Denatured, or industrial, alcohol is ethanol to which poisonous or nauseating substances have been added to prevent its use as a beverage; a beverage tax is not charged on such alcohol, so its cost is quite low. Medically, ethanol is a soporific, i.e., sleep-producing; although it is less toxic than the other alcohols, death usually occurs if the concentration of ethanol in the bloodstream exceeds about 5%. Behavioral changes, impairment of vision, or unconsciousness occur at lower concentrations. See alcoholismalcoholism,
disease characterized by impaired control over the consumption of alcoholic beverages. Alcoholism is a serious problem worldwide; in the United States the wide availability of alcoholic beverages makes alcohol the most accessible drug, and alcoholism is the most
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.

ethanol

[′eth·ə‚nȯl]
(organic chemistry)
C2H5OH A colorless liquid, miscible with water, boiling point 78.32°C; used as a reagent and solvent. Also known as ethyl alcohol; grain alcohol.
References in periodicals archive ?
De igual forma, reactivar el Programa Nacional de Etanol, revitalizando destilerias en ingenios, implementacion de metodologias y tecnicas para la produccion mas limpia (P+L), analisis de ciclo de vida (LCA), huella de carbono, agua y emisiones de gases de efecto invernadero (GEI), facilitara a las plantas de azucar, piloncillo etanol y energia electrica certificarse internacionalmente y ser competitivos.
Desde la ecologia politica, en este articulo analizare la magnitud y el significado de las transformaciones ocurridas en el valle del Chira y en el pais desde mediados de la decada de 2000, a proposito de la promocion y siembra de cultivos energeticos tales como la cana de azucar para etanol.
Otro aspecto que se debe considerar de la Tabla 3, es la composicion de celulosa del bagazo de sorgo dulce; dicha composicion convierte este residuo agroindustrial en un sustrato prometedor, que podria utilizarse en la produccion de etanol de segunda generacion.
Em goiabas 'Kumagai' submetidas a imersao em etanol 50%, durante dois minutos, Ponzo (2009) conseguiu reduzir a incidencia e a severidade da antracnose em frutos inoculados com C.
Para os frutos controle e do tratamento etanol+cloro/termoterapia a acidez reduziu no oitavo dia de armazenamento e para os frutos tratados termicamente ou com etanol e que receberam aplicacao de fecula, a acidez manteve-se ao longo do armazenamento.
Para establecer si la capsaicina diluida en etanol 0,05 % tiene un efecto en la disminucion de la produccion de [PGE.
En este sentido, el objeto del presente articulo sera tratar de explicar de una forma sistematica como los condicionantes politicos, economicos y juridicos vinculados al uso energetico de la biomasa agricola se han asociado y disociado en el tiempo, y como esta relacion se vincula al desarrollo historico del etanol carburante en Brasil.
De esa ventaja evolutiva, la metabolizacion del etanol, se ha pasado actualmente a un grave problema social, pues la Organizacion Mundial de la Salud (OMS) estima que el consumo de alcohol contribuye con mas de 200 enfermedades y lesiones, como la cirrosis hepatica y algunos canceres.
En esta ley se propone el uso de una mezcla de 90 % gasolina y 10 % etanol para cumplir con esta normativa [7].
El residuo se lavo con 120 mL de agua destilada, 80 mL de etanol y 150 mL de acetona.
Para la elaboracion de este combustible se ha utilizado la levadura Kluyveromyces marxianus, la cual ha sido ampliamente utilizada en el bioprocesamiento del suero de leche y es capaz de fermentar la lactosa a etanol directamente (Christensen et al.
El grado de lipoperoxidacion fue significativamente menor en el grupo que consumio la mas alta dosis de tocosh (G5), es decir con mayor efecto antioxidante, y fue significativamente mayor en el grupo al que se le administro solo etanol (G2) p<0,01, es decir, donde se observo mayor estres oxidativo.