Difference between revisions of "Sodium methoxide"

Revision as of 17:09, 7 August 2017

Sodium methoxide is a chemical compound with the formula CH₃ONa. It is a dangerously caustic base.

Properties

Chemical

Sodium methoxide hydrolyzes on contact with water, forming sodium hydroxide and methanol. The reaction gives off lots of heat, which may ignite the methanol vapors.

CH₃ONa + H₂O → NaOH + CH₃OH

Reaction with halocarbons will give orthoesters, such as trimethyl orthoformate from chloroform:

3 CH₃ONa + CHCl₃ → HC(CH₃O)₃ + 3 NaCl

Sodium methoxide will react with carboxylic acid to give esters:

CH₃ONa + CH₃COOH → NaOH + CH₃COO-CH₃

Physical

Sodium methoxide is a colorless solid, which hydrolyzes in contact with water, but is soluble in alcohols.

Availability

Sodium hydroxide can be purchased online from suppliers, but due to its hazards it's relative difficult to get hold of.

Preparation

Sodium methoxide can be prepared by reacting metallic sodium with an excess of anhydrous methanol. The resulting sodium methoxide can be purified by recrystallizing it from solution.

CH₃OH + Na → CH₃ONa + ½ H₂

Since this reaction produces hydrogen and lots of heat, it's best to perform it in an oxygen-less atmosphere, in a well ventilated area.

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.

Projects

• Make orthoformate esters
• Make esters

Handling

Safety

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.

Storage

Sodium methoxide should be stored in air-tight containers, or in a desiccator.

Disposal

Sodium methoxide can be neutralized by dissolving it in large amounts of water slowly, then neutralize the resulting sodium hydroxide.

References

Relevant Sciencemadness threads

• Best route to Sodium Methoxide
• Sodium methoxyde by electrolysis?
• Sodium from sodium methoxide electrolysis in pentane