any of a number of organic compounds whose molecules contain two hydrocarbon groups joined by single bonds to an oxygen atom. The most common of these compounds is ethyl ether, CH₃CH₂OCH₂CH₃, often called simply ether, a colorless, volatile liquid with a distinctive odor; its IUPAC name is ethoxyethane. Ethyl ether boils at 34.5 degrees Celsius and is extremely flammable. It is insoluble in water but mixes with many organic solvents and is widely used as a solvent itself, e.g., for fats and oils. Its most familiar historical application is as an anesthetic. An ether such as ethyl ether in which both hydrocarbon groups are identical is said to be a simple, or symmetrical, ether. An ether in which the two groups differ (e.g., methyl ethyl ether, CH₃OCH₂CH₃) is said to be a mixed, or unsymmetrical, ether. Ethers are often prepared commercially by heating an alcohol with sulfuric acid; the reaction is one of dehydration. In the laboratory ethers are often prepared by reaction of an alkyl halide with a sodium alkoxide (a method called the Williamson synthesis). Ethers are usually chemically unreactive but can be cleaved (broken apart) at high temperatures by concentrated hydrogen halides; initially an alkyl halide and an alcohol are formed. Epoxides are a special class of cyclic ethers.

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