Alkylethers

Alkylethers, or alkyl ethers, are organic compounds in which an oxygen atom links two alkyl groups (R–O–R′). They are a subset of ethers and can be symmetric (R = R′) or asymmetric (R ≠ R′). Common examples include diethyl ether (Et–O–Et), diisopropyl ether, methyl tert-butyl ether (MTBE), and dimethyl ether.

Properties of alkylethers include relatively low polarity for many simple examples, and a tendency to be liquids or gases at room temperature with boiling points that increase as the alkyl chains grow. The oxygen atom provides a lone pair that can coordinate to Lewis acids, making ethers useful as solvents for a wide range of reactions. Ethers generally dissolve nonpolar and moderately polar substances well but are less miscible with water as their alkyl groups become larger. They are prone to forming explosive peroxides on storage in air, particularly diethyl ether and THF, so proper handling and storage are important.

Preparation methods

- Williamson ether synthesis: deprotonation of an alcohol to form an alkoxide, followed by SN2 reaction with a primary alkyl halide or sulfonate to yield an asymmetric ether.

- Acid-catalyzed dehydration of alcohols: two alcohol molecules react under strong acid to form an ether and water; this method can be less selective for unsymmetrical ethers and often favors symmetrical products.

Other routes include condensation of alcohol derivatives under suitable conditions and, in some cases, alkylation of alcohols with activated electrophiles.

Reactions and uses

Ethers are relatively stable to most reagents but can be cleaved by strong acids or strong hydrogen halides to give alcohols and alkyl halides. In industry, alkylethers serve as solvents for polymers, coatings, and pharmaceuticals. MTBE has been used as a gasoline oxygenate additive; diethyl ether historically served as a versatile solvent and, in the past, as an anesthetic. Safety concerns include flammability and peroxide formation, requiring proper storage and handling.