Sodium methoxide

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Sodium methoxide
IUPAC name

sodium methoxide

Other names

sodium methylate

Identifiers
CAS number 124-41-4 YesY
PubChem 10942334
ChemSpider 29033 YesY
UNII IG663U5EMC YesY
Jmol-3D images {{#if:[Na+].[O-]C|Image 1
Properties
Molecular formula CH3NaO
Molar mass 54.02
Appearance white solid
Melting point 127 ºC
Boiling point >300 °C
Solubility soluble in ethanol, methanol, fats, esters
insoluble in hydrocarbons
Structure
Crystal structure hexagonal
Hazards
EU classification Harmful (Xn), Corrosive (C)
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, 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 formula CH3ONa. This colourless solid, which is formed by the deprotonation of methanol, is a widely used reagent in industry and the laboratory. It is also a dangerously caustic base.

Preparation and structure

Sodium methoxide is prepared by carefully treating methanol with sodium:

2 Na + 2 CH
3OH → 2 CH
3ONa + H
2

The reaction is so exothermic that ignition is possible. The resulting solution, which is colorless, is often used as a source of sodium methoxide, but the pure material can be isolated by evaporation followed by heating to remove residual methanol. The solid hydrolyzes in water to give sodium hydroxide, and commercial samples can be contaminated with the hydroxide. The solid and especially solutions absorb carbon dioxide from the air, thus diminishing the effectiveness of the base.

In the solid form, sodium methoxide is polymeric, with a sheet-like arrays of Na+ centers, each bonded to four oxygen centers.[1]

The structure, and hence its basicity, of sodium methoxide in solution depends on the solvent. It is significantly stronger base in DMSO where it is more fully ionized and free of hydrogen bonding.[2]

Applications

Organic synthesis

Sodium methoxide is a routine base in organic chemistry, applicable to the synthesis of numerous compounds, ranging from pharmaceuticals to agrichemicals.[2] As a base, it is employed in dehydrohalogenations and various condensations.[3] It is also a nucleophile for the production of methyl ethers.[4]

Industrial applications

Sodium methoxide is used as an initiator of anionic addition polymerization with ethylene oxide, forming a polyether with high molecular weight. Biodiesel is prepared from vegetable oils and animal fats, that is, fatty acid triglycerides, by transesterification with methanol to give fatty acid methyl esters (FAMEs). This transformation is catalyzed by sodium methoxide.

Safety

Sodium methoxide is highly caustic, and the hydrolysis gives methanol, which is toxic and volatile.

NFPA 704

The ratings for this substance vary widely.

Rating
4
3
3
 
4
3
2
 
3
3
2
 
2
3
2
 
2
2
2
 
Source State of Connecticut[5] DuPont[6] Pharmco AAPR[7] ScienceLab[8](Both ratings on same sheet)

See also

References

  1. ↑ E. Weiss, “Die Kristallstruktur des Natriummethylats” Zeitschrift fur Anorganische und Allgemeine Chemie 1964, volume 332, p. 197-203. doi:10.1002/zaac.19643320311
  2. ↑ 2.0 2.1 Y. El-Kattan, J. McAtee, B. Bessieres “Sodium Methoxide” in Encyclopedia of Reagents for Organic Synthesis, John Wiley & Sons, 2006, New York. doi:10.1002/047084289X.rs089m.pub2. Article Online Posting Date: September 15, 2006.
  3. ↑ Omer E. Curtis, Jr., Joseph M. Sandri, Richard E. Crocker, Harold Hart (1963), "dicyclopropyl ketone", Org. Synth. ; Coll. Vol. 4: 278 
  4. ↑ Frederic Reverdin (1941), "3,5-Dinitroanisole", Org. Synth. ; Coll. Vol. 1: 219 
  5. ↑ "The Code Officials Perspective". 
  6. ↑ "DuPont Material Safety Data Sheet". 
  7. ↑ "Pharmco AAPR Material Safety Data Sheet". 
  8. ↑ "ScienceLab Material Safety Data Sheet". 
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