Sodium ethoxide

Sodium ethoxide is the organic compound with the formula C₂H₅ONa. It is a white solid, although impure samples appear yellow or brown. It dissolves in polar solvents such as ethanol. It is commonly used as a strong base.

Solid samples of sodium ethoxide gradually turn dark on storage in dry air because of oxidation. In moist air, it hydrolyzes rapidly to sodium hydroxide. The conversion is not obvious and typical samples of NaOEt are contaminated with NaOH.

Sodium ethoxide is commonly used in the Claisen condensation and malonic ester synthesis. Sodium ethoxide may either deprotonate the α-position of an ester molecule, forming an enolate, or the ester molecule may undergo a nucleophilic substitution called transesterification. If the starting material is an ethyl ester, trans-esterification is irrelevant since the product is identical to the starting material. In practice, the alcohol/alkoxide solvating mixture must match the alkoxy components of the reacting esters to minimize the number of different products.

Many alkoxides are prepared by salt metathesis from sodium ethoxide.