Ether is a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether" (CH3-CH2-O-CH2-CH3). Ethers are common in organic chemistry and pervasive in biochemistry, as they are common linkages in carbohydrates and lignin.
Structure and bonding
Ethers feature C-O-C linkage defined by a bond angle of about 110° and C-O distances of about 140 pm. The barrier to rotation about the C-O bonds is low. The bonding of oxygen in ethers, alcohols, and water is similar. In the language of valence bond theory, the hybridization at oxygen is sp3.
Oxygen is more electronegative than carbon, thus the hydrogens alpha to ethers are more acidic than in simple hydrocarbons. They are far less acidic than hydrogens alpha to ketones, however.
The names for simple ethers (i.e. those with none or few other functional groups) are a composite of the two substituents followed by "ether." Methyl ethyl ether (CH3OC2H5), diphenylether (C6H5OC6H5). IUPAC rules are often not followed for simple ethers. As for other organic compounds, very common ethers acquired names before rules for nomenclature were formalized. Diethyl ether is simply called "ether," but was once called sweet oil of vitriol. Methyl phenyl ether is anisole, because it was originally found in aniseed. The aromatic ethers include furans. Acetals (α-alkoxy ethers R-CH(-OR)-O-R) are another class of ethers with characteristic properties.
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