Freshly prepared sodium methoxide
| IUPAC name
| Other names
|Molar mass||54.02 g/mol|
|Melting point||127 °C (261 °F; 400 K)|
|Boiling point||> 300 °C (572 °F; 573 K)|
|Solubility|| Reacts with carboxylic acids, halocarbons, mineral acids|
Soluble in DMSO, ethanol, lipids, methanol, oils
Slightly soluble in pentane
|Safety data sheet||Sigma-Aldrich|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Sodium methoxide is a chemical compound with the formula CH3ONa. It is a dangerously moisture-sensitive caustic base, widely used in organic chemistry.
- CH3ONa + H2O → NaOH + CH3OH
- 3 CH3ONa + CHCl3 → HC(CH3O)3 + 3 NaCl
If sodium methoxide reacts with an alkyl halide, a methyl containing ether will be formed. This reaction is very useful when making asymmetrical ethers, which are difficult to prepare, such as methyl tert-butyl ether:
- CH3ONa + (CH3)3C-I → (CH3)3COCH3 + NaI
This reaction is called Williamson ether synthesis.
Sodium methoxide will react with carboxylic acid to give esters:
- CH3ONa + CH3COOH → NaOH + CH3COO-CH3
Sodium methoxide is a colorless solid, which hydrolyzes in contact with water, but is soluble in alcohols.
Sodium hydroxide can be purchased online from suppliers, but due to its hazards it's relative difficult to get hold of.
- CH3OH + Na → CH3ONa + ½ H2
A more safe route involves the reaction of sodium hydroxide with anhydrous methanol, in the presence of a desiccator, such as molecular sieves. In a flask, add 200 ml of anhydrous methanol and 40 g of sodium hydroxide and begin stirring until it completely dissolves. After it dissolved, add 100 g of dried 3A molecular sieves. Seal the flask, mark the methanol level and wait a few days. After the level of the methanol no longer decreases, filter the resulting solution and recrystallize the sodium methoxide. If the solution wasn't dried completely, simply change the sieves and repeat.
- Make orthoformate esters
- Make esters
Sodium methoxide is caustic and contact with skin will cause chemical burns. Reaction with water will give methanol and lots of heat, which may ignite the methanol vapors.
Sodium methoxide should be stored in air-tight containers, or in a desiccator.
Sodium methoxide can be neutralized by dissolving it in large amounts of water slowly, then neutralize the resulting sodium hydroxide with a weak acid or sodium bicarbonate.