Difference between revisions of "Sodium methoxide"
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| OtherNames = Methoxysodium<br>Sodium methanolate<br>Sodium methylate | | OtherNames = Methoxysodium<br>Sodium methanolate<br>Sodium methylate | ||
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| + | | Odor = Odorless | ||
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| pKb = | | pKb = | ||
| Solubility = Reacts | | Solubility = Reacts | ||
| − | | SolubleOther = Reacts with [[carboxylic acid]]s, halocarbons<br>Soluble in [[dimethyl sulfoxide|DMSO]], [[ethanol]], lipids, [[methanol]], oils<br>Slightly soluble in [[pentane]] | + | | SolubleOther = Reacts with [[carboxylic acid]]s, halocarbons, mineral acids<br>Soluble in [[dimethyl sulfoxide|DMSO]], [[ethanol]], lipids, [[methanol]], oils<br>Slightly soluble in [[pentane]] |
| Solvent = | | Solvent = | ||
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| − | '''Sodium methoxide''' is a chemical compound with the formula '''CH<sub>3</sub>ONa'''. It is a dangerously caustic base. | + | '''Sodium methoxide''' is a chemical compound with the formula '''CH<sub>3</sub>ONa'''. It is a dangerously moisture-sensitive caustic base, widely used in organic chemistry. |
==Properties== | ==Properties== | ||
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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. | 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. | ||
| − | :CH<sub>3</sub>ONa + H<sub>2</sub>O → NaOH + CH<sub>3</sub>OH | + | : CH<sub>3</sub>ONa + H<sub>2</sub>O → NaOH + CH<sub>3</sub>OH |
Reaction with halocarbons will give orthoesters, such as [[trimethyl orthoformate]] from [[chloroform]]: | Reaction with halocarbons will give orthoesters, such as [[trimethyl orthoformate]] from [[chloroform]]: | ||
:3 CH<sub>3</sub>ONa + CHCl<sub>3</sub> → HC(CH<sub>3</sub>O)<sub>3</sub> + 3 NaCl | :3 CH<sub>3</sub>ONa + CHCl<sub>3</sub> → HC(CH<sub>3</sub>O)<sub>3</sub> + 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]]: | ||
| + | |||
| + | : CH<sub>3</sub>ONa + (CH<sub>3</sub>)<sub>3</sub>C-I → (CH<sub>3</sub>)<sub>3</sub>COCH<sub>3</sub> + NaI | ||
| + | |||
| + | This reaction is called Williamson ether synthesis. | ||
Sodium methoxide will react with carboxylic acid to give esters: | Sodium methoxide will react with carboxylic acid to give esters: | ||
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===Physical=== | ===Physical=== | ||
| − | Sodium methoxide is a colorless solid, which hydrolyzes in water, but is soluble in alcohols. | + | Sodium methoxide is a colorless solid, which hydrolyzes in contact with water, but is soluble in alcohols. |
==Availability== | ==Availability== | ||
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==Preparation== | ==Preparation== | ||
| − | Sodium methoxide can be prepared by | + | Sodium methoxide can be prepared by slowly and carefully adding metallic [[sodium]] to an excess of anhydrous [[methanol]]. The resulting sodium methoxide can be purified by recrystallizing it from solution. |
| − | :CH<sub>3</sub>OH + Na → CH<sub>3</sub>ONa + ½ H<sub>2</sub> | + | : CH<sub>3</sub>OH + Na → CH<sub>3</sub>ONa + ½ H<sub>2</sub> |
| − | 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. | + | Since this reaction produces [[hydrogen]] and lots of heat, it's best to perform it in an ice bath, best in an oxygen-less atmosphere, in a well ventilated area.<ref>https://www.youtube.com/watch?v=IUBoi5He3Zc</ref> |
| − | A more safe route involves the reaction of sodium hydroxide with anhydrous methanol, in the presence of a desiccator, such as [[molecular sieve | + | A more safe route involves the reaction of sodium hydroxide with anhydrous methanol, in the presence of a desiccator, such as [[molecular sieve]]s. 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== | ==Projects== | ||
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===Disposal=== | ===Disposal=== | ||
| − | Sodium methoxide can be neutralized by dissolving it in large amounts of water slowly, then neutralize the resulting sodium hydroxide. | + | 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. |
==References== | ==References== | ||
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[[Category:Methoxides]] | [[Category:Methoxides]] | ||
[[Category:Bases]] | [[Category:Bases]] | ||
| + | [[Category:Superbases]] | ||
[[Category:Materials that react with water]] | [[Category:Materials that react with water]] | ||
[[Category:Materials unstable in acidic solution]] | [[Category:Materials unstable in acidic solution]] | ||
[[Category:Materials unstable in basic solution]] | [[Category:Materials unstable in basic solution]] | ||
[[Category:Corrosive chemicals]] | [[Category:Corrosive chemicals]] | ||
| + | [[Category:Air-sensitive materials]] | ||
Latest revision as of 20:55, 10 October 2019
 Freshly prepared sodium methoxide
| |
| Names | |
|---|---|
| IUPAC name
Sodium methoxide
| |
| Other names
Methoxysodium
Sodium methanolate Sodium methylate | |
| Properties | |
| CH3ONa | |
| Molar mass | 54.02 g/mol |
| Appearance | White solid |
| Odor | Odorless |
| Density | 1.3 g/cm3 |
| Melting point | 127 °C (261 °F; 400 K) |
| Boiling point | > 300 °C (572 °F; 573 K) |
| Reacts | |
| Solubility | Reacts with carboxylic acids, halocarbons, mineral acids Soluble in DMSO, ethanol, lipids, methanol, oils Slightly soluble in pentane |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Related compounds | |
| Related compounds
|
Sodium ethoxide |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Sodium methoxide is a chemical compound with the formula CH3ONa. It is a dangerously moisture-sensitive caustic base, widely used in organic chemistry.
Contents
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
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
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 slowly and carefully adding metallic sodium to 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 ice bath, best in an oxygen-less atmosphere, in a well ventilated area.[1]
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 with a weak acid or sodium bicarbonate.
