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AlcoholIn chemistry, an alcohol is any organic compound in which a hydroxyl group (-OH) is bound to a carbon atom of an alkyl or substituted alkyl group. The general formula for a simple acyclic alcohol is CnH2n+1OH. In general usage, alcohol refers almost always to ethanol, also known as grain alcohol, an odorless, colorless, volatile liquid, formed by the fermentation of sugars. It also often refers to any beverage that contains ethanol (see alcoholic beverage). This sense underlies the term alcoholism (addiction to alcohol). As a drug, ethanol is known to have a depressing effect that decreases the responses of the central nervous system (see effects of alcohol on the body). Other forms of alcohol are usually described with a clarifying adjective, as in isopropyl alcohol or by the suffix -ol, as in isopropanol. The functional group of an alcohol is a hydroxyl group bonded to an sp³ hybridized carbon. It can therefore be regarded as a derivative of water, with an alkyl group replacing one of the hydrogens. If an aryl group is present rather than an alkyl, the compound is generally called a phenol rather than an alcohol. Also, if the hydroxyl group is bonded to one of the sp² hybridized carbons of an alkenyl group, the compound is referred to as an enol. The oxygen in an alcohol has a bond angle of around 109° (c.f. 104.5° in water), and two nonbonded electron pairs. The O-H bond in methanol (CH3OH) is around 96 picometres long. There are three major subsets of alcohols- 'primary' (1°), 'secondary' (2°) and 'tertiary' (3°), based upon the number of carbons the C-OH carbon (shown in red) is bonded to. Methanol is the simplest 'primary' alcohol. The simplest secondary alcohol is isopropanol (propan-2-ol), and a simple tertiary alcohol is tert-butanol (2-methylpropan-2-ol). The phenols with parent compound phenol have a hydroxyl group (attached to an benzene ring) just like alcohols but differ sufficiently in properties to warrant a separate treatment. The simplest and most commonly used alcohols are methanol and ethanol (common names methyl alcohol and ethyl alcohol, respectively), which have the structures shown above. Methanol was formerly obtained by the distillation of wood, and was called "wood alcohol." It is now a cheap commodity, chemical produced by the high pressure reaction of carbon monoxide with hydrogen. In common usage, "alcohol" often refers simply to ethanol or "grain alcohol." Methylated spirits ("Meths"), also called "surgical spirits," is a form of ethanol rendered undrinkable by the addition of methanol. Aside from its major use in alcoholic beverages, ethanol is also used (although highly controlled) as an industrial solvent and raw material. Alcohols are in wide use in industry and science as reagents, solvents, and fuels. Ethanol and methanol can be made to burn more cleanly than gasoline or diesel. Because of its low toxicity and ability to dissolve non-polar substances, ethanol is often used as a solvent in medical drugs, perfumes, and vegetable essences such as vanilla. In organic synthesis, alcohols frequently serve as versatile intermediates. In the kitchen, alcoholic beverages are added to dishes not only for their inherent flavors, but because the alcohol dissolves flavor compounds that water can not. Check out the following recipes that are tagged "Alcohol":
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