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Sodium methoxide is prepared by carefully treating methanol with sodium:
Sodium methoxide is prepared by carefully treating methanol with sodium:


:2 Na + 2 {{chem|CH|3|OH}} → 2 {{chem|CH|3|ONa}} + {{chem|H|2|O}}
:2 Na + 2 {{chem|CH|3|OH}} → 2 {{chem|CH|3|ONa}} + {{chem|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 methanol and [[sodium hydroxide]]; commercial-grade product can be contaminated with the hydroxide. The solid and especially solutions absorb [[carbon dioxide]] from the air, thus diminishing the effectiveness of the base.
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 methanol and [[sodium hydroxide]]; commercial-grade product can be contaminated with the hydroxide. The solid and especially solutions absorb [[carbon dioxide]] from the air, thus diminishing the effectiveness of the base.

Revision as of 03:33, 25 November 2015

Sodium methoxide
The sodium cation
The sodium cation
Ball-and-stick model of the methoxide anion
Ball-and-stick model of the methoxide anion
Names
IUPAC name
Sodium methoxide
Other names
Sodium methylate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.273 Edit this at Wikidata
UNII
  • InChI=1S/CH3O.Na/c1-2;/h1H3;/q-1;+1 checkY
    Key: WQDUMFSSJAZKTM-UHFFFAOYSA-N checkY
  • InChI=1/CH3O.Na/c1-2;/h1H3;/q-1;+1
    Key: WQDUMFSSJAZKTM-UHFFFAOYAC
  • [Na+].[O-]C
Properties
CH3NaO
Molar mass 54.02 g/mol
Appearance White solid
Melting point 127 °C (261 °F; 400 K)
Boiling point > 300 °C (572 °F; 573 K)
Solubility Soluble in ethanol, methanol, fats, esters
Insoluble in hydrocarbons
Structure
Hexagonal
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Sodium methoxide is a chemical compound with the formula CH3ONa. This colorless 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 methanol and sodium hydroxide; commercial-grade product 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 a significantly stronger base in DMSO where it is more fully ionized and free of hydrogen bonding.[2]

Applications

Organic synthesis

Sodium methoxide is a routinely used 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
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
3
4
3
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
3
4
2
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
3
3
2
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
3
2
2
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
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 (1964). "Die Kristallstruktur des Natriummethylats". Zeitschrift für Anorganische und Allgemeine Chemie (in German). 332 (3–4): 197–203. doi:10.1002/zaac.19643320311. {{cite journal}}: Unknown parameter |trans_title= ignored (|trans-title= suggested) (help)
  2. ^ a b Y. El-Kattan, J. McAtee, B. Bessieres (2006). "Sodium Methoxide". Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rs089m.pub2.{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link)
  3. ^ O. E. Curtis, Jr., J. M. Sandri, R. E. Crocker, H. Hart (1958). "Dicyclopropyl ketone". Organic Syntheses. 38: 19. doi:10.15227/orgsyn.038.0019{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 278.
  4. ^ F. Reverdin (1927). "3,5-Dinitroanisole". Organic Syntheses. 7: 28. doi:10.15227/orgsyn.007.0028; Collected Volumes, vol. 1, p. 219.
  5. ^ "The Code Officials Perspective" (PDF).
  6. ^ "DuPont Material Safety Data Sheet" (PDF).
  7. ^ "Pharmco AAPR Material Safety Data Sheet" (PDF).
  8. ^ "ScienceLab Material Safety Data Sheet".
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