Ether (chemistry)

Ethers (/ˈiːθər/) are a class of organic compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula R–O–R′, where R and R′ represent the alkyl or aryl groups. Ethers can again be classified into two varieties: if the alkyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group 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.

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 carbonyl groups (such as in ketones or aldehydes), however.

In the IUPAC nomenclature system, ethers are named using the general formula "alkoxyalkane", for example CH₃–CH₂–O–CH₃ is methoxyethane. If the ether is part of a more complex molecule, it is described as an alkoxy substituent, so –OCH₃ would be considered a "methoxy-" group. The simpler alkyl radical is written in front, so CH₃–O–CH₂CH₃ would be given as methoxy(CH₃O)ethane(CH₂CH₃).

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