Williamson synthesis is a laboratory method for preparing symmetrical and unsymmetrical ethers by reacting alkyl halides with sodium alkoxide. It is especially effective for ethers containing substituted alkyl groups, and better results are obtained when the alkyl halide is primary.

The reaction in Williamson synthesis involves an SN₂ attack of an alkoxide ion on a primary alkyl halide. Primary alkyl halides are preferred as better results are obtained, whereas secondary and tertiary alkyl halides may lead to elimination reactions, with ...

Dehydration of secondary and tertiary alcohols fails to yield ethers, as elimination competes over substitution. Consequently, alkenes are easily formed, and the reaction follows an SN₁ pathway, a concept elaborated upon in higher classes.

The formation of ethers during acidic dehydration involves a nucleophilic bimolecular (SN₂) reaction, where the alcohol molecule attacks a protonated alcohol. This method is suitable for preparing ethers with primary alkyl groups, requiring unhindered alkyl groups and low temperatures.

The formation of alkene or ether in alcohol dehydration depends on the reaction conditions. For instance, the dehydration of ethanol results in ethene at 443 K, while at 413 K, ethoxyethane is the main product, showcasing the influence of temperature.