Sodium methoxide

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Sodium methoxide
Sodium methoxide.png
The sodium cation Ball-and-stick model of the methoxide anion
Identifiers
CAS number 124-41-4 YesY
PubChem 10942334
ChemSpider 29033 YesY
UNII IG663U5EMC YesY
Jmol-3D images 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)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Sodium methoxide is a chemical compound with the 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[edit]

Sodium methoxide is prepared by carefully treating methanol with sodium:

2 Na + 2 CH
3
OH
→ 2 CH
3
ONa
+ 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[edit]

Organic synthesis[edit]

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[edit]

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[edit]

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

NFPA 704[edit]

The ratings for this substance vary widely.

Rating
Flammability code 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., propane Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 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., fluorine Special hazards (white): no codeNFPA 704 four-colored diamond
Flammability code 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., propane Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Flammability code 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., gasoline) Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Flammability code 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 fuel Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Flammability code 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 fuel Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Source State of Connecticut[5] DuPont[6] Pharmco AAPR[7] ScienceLab[8](Both ratings on same sheet)

See also[edit]

References[edit]

  1. ^ E. Weiss (1964). "Die Kristallstruktur des Natriummethylats" [The Crystal Structure of Sodium Methylate]. Zeitschrift für Anorganische und Allgemeine Chemie (in German) 332 (3–4): 197–203. doi:10.1002/zaac.19643320311. 
  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. 
  3. ^ O. E. Curtis, Jr., J. M. Sandri, R. E. Crocker, H. Hart (1958), "Dicyclopropyl ketone", Org. Synth. 38: 19, doi:10.15227/orgsyn.038.0019 ; Coll. Vol. 4: 278 
  4. ^ F. Reverdin (1927), "3,5-Dinitroanisole", Org. Synth. 7: 28, doi:10.15227/orgsyn.007.0028 ; 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".