Williamson ether synthesis

The most versatile method for making ethers is the Williamson ether synthesis, named for English chemist Alexander Williamson, who devised the method in the 19th century. It uses an alkoxide ion to attack an alkyl halide, substituting the alkoxy (―O―R) group for the halide. The alkyl halide must be unhindered (usually primary), or elimination will compete with the desired substitution.

Ether. Chemical Compounds. Williamson ether synthesis uses an alkoxide ion to attack an alkyl halide, substituting the alkoxy group for the halide.

Bimolecular dehydration

In the presence of acid, two molecules of an alcohol may lose water to form an ether. In practice, however, this bimolecular dehydration to form an ether competes with unimolecular dehydration to give an alkene. Bimolecular dehydration produces useful yields of ethers only with simple, primary alkyl groups such as those in dimethyl ether and diethyl ether. Dehydration is used commercially to produce diethyl ether.

Ether. Chemical Compounds. Examples of bimolecular dehydration.

Reactions of ethers

Cleavage

Ethers are good solvents partly because they are not very reactive. Most ethers can be cleaved, however, by hydrobromic acid (HBr) to give alkyl bromides or by hydroiodic acid (HI) to give alkyl iodides.

Ether. Chemical Compounds. Most ethers can be cleaved by hydrobromic acid to give alkyl bromides or by hydroiodic acid to give alkyl iodides.

Autoxidation

Autoxidation is the spontaneous oxidation of a compound in air. In the presence of oxygen, ethers slowly autoxidize to form hydroperoxides and dialkyl peroxides. If concentrated or heated, these peroxides may explode. To prevent such explosions, ethers should be obtained in small quantities, kept in tightly sealed containers, and used promptly.

Ether. Chemical Compounds. Autoxidation of ether to form hydroperoxides and dialkyl peroxides.

Leroy G. Wade
Also called:
diethyl ether
Related Topics:
ether

ethyl ether, well-known anesthetic, commonly called simply ether, an organic compound belonging to a large group of compounds called ethers; its molecular structure consists of two ethyl groups linked through an oxygen atom, as in C2H5OC2H5.

Ethyl ether is a colourless, volatile, highly flammable liquid (boiling point 34.5° C [94.1° F]) with a powerful, characteristic odour and a hot, sweetish taste. It is a widely used solvent for bromine, iodine, most fatty and resinous substances, volatile oils, pure rubber, and certain vegetable alkaloids.

Ethyl ether is manufactured by the distillation of ethyl alcohol with sulfuric acid. Pure ether (absolute ether), required for medical purposes and in the preparation of Grignard reagents, is prepared by washing the crude ether with a saturated aqueous solution of calcium chloride, then treating with sodium.