Category: Economic botany and plant uses
Ethanol, sometimes called grain alcohol, is an alcohol produced by fermentation of carbohydrates from a broad range of plant matter for many uses in the chemical industry. It has potentially significant use as a gasoline replacement and is also the primary alcohol component of alcoholic beverages.
Ethanol is produced by carbohydrate fermentation processes, hydration of ethylene, and, to a lesser extent, reduction of acetaldehyde obtained from acetylene. Also called ethyl alcohol, alcohol, and grain alcohol, ethanol is a colorless liquid with a mild and distinct aroma and taste. It has a boiling point of 78.3 degrees Celsius and a melting point of 114.5 degrees Celsius. Ethanol is completely soluble in water and most organic solvents. It has a flash point of 8 degrees Celsius and is thus highly flammable. Ethanol undergoes numerous commercially important reactions and is thus a vital industrial chemical. It has been used as a partial replacement for gasoline (the hybrid fuel is called "gasohol"). As the major component of alcoholic beverages, ethanol has been known and recognized for thousands of years.
Alcohol obtained from fermentation processes is generally included with other fermentation products and extracts from the carbohydrate-rich grains, fruits, and so on that are the raw materials for the many alcoholic beverages produced and consumed. Alcohol produced by yeast fermentation is obtained at a maximum concentration of 14 percent; therefore, alcoholic beverages other than beer and nonfortified wines require the addition of concentrated alcohol, which is obtained by distilling dilute alcohol from the fermentation of molasses and other sugar sources. In the United States and other highly industrialized countries, the alcohol added to beverages is increasingly being produced by other methods.
Ethanol is also used in large quantities for chemical synthesis in the organic chemical industry. It is used for the preparation of numerous esters vital to many polymer industries and for the production of diethyl ether (also called ether or ethyl ether), a ma jor solvent. Other synthetic procedures lead to the manufacture of acetaldehyde, acetic acid, ethyl halides, and acetonitrile, which are in turn employed for the preparation of drugs, explosives, ad-hesives, pesticides, detergents, synthetic fibers, and other substances. Ethanol itself is used in vast quantities as a solvent.
Ethanol is added to gasoline to reduce air pollution, and it is frequently considered to be a likely replacement for gasoline when petroleum resources decline or drastically increase in price. Gasohol, ethanol combined with varying amounts of gasoline, is being vigorously promoted and is already in use in Brazil and elsewhere. Biomass conversion (conversion of plant matter) to ethanol by cost-efficient methods will speed the entry of gasohol into large-scale use in the industrial world.
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