User:Rifleman 82/sandbox
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| Names | |
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| IUPAC name
Dimethyl carbonate
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| Other names
DMC
Methyl carbonate Carbonic acid, dimethyl ester | |
| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
PubChem CID
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| UNII | |
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| Properties | |
| C3H6O3 | |
| Molar mass | 90.08 g/mol |
| Appearance | Clear liquid |
| Density | 1.069 - 1.073 g/ml, liquid |
| Melting point | 2 - 4 °C (275 - 277 K) |
| Boiling point | 90 °C (363 K) |
| 13.9 g/100 ml water | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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Flammable |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Dimethyl carbonate, often abbreviated DMC, a carbonate ester, is a flammable clear liquid boiling at 90 °C. This compound has found use as a methylating agent. There is also interest in using this compound as a fuel oxygenate additive,[1] and as a solvent. It was classified as an exempt compound under the definition of volatile organic compounds by the U.S. EPA in 2009.[2]
Production
[edit]Dimethyl carbonate may be prepared by reaction of phosgene with methanol via methyl chloroformate:
- COCl2 + CH3OH → CH3OCOCl + HCl
- CH3OCOCl + CH3OH → CH3OCO2CH3 + HCl
Overall:
- COCl2 + 2 CH3OH → CH3OCO2CH3 + 2 HCl
This process is undesirable because of phosgene's toxicity. Many other routes have been found, and some of them have been commercialized. World production in 1997 was estimated at 1000 barrels a day.[1][3]
Reactions
[edit]Dimethyl carbonate's main benefit over other methylating reagents such as iodomethane and dimethyl sulfate is its much lower toxicity and its biodegradability.[4] Also, it is now prepared from catalytic oxidative carbonylation of methanol with carbon monoxide and oxygen, instead of from phosgene.[4] This allows dimethyl carbonate to be considered a green reagent.
Dimethyl carbonate is able to methylate anilines, phenols and carboxylic acids, but many of these reactions require the use of an autoclave.[5] One alternative involves the use of DBU, which allows methylation of phenols, indoles, and benzimidazoles[6] and the preparation of methyl carboxylate esters:[5]
References
[edit]- ^ a b Pacheco, Michael A.; Marshall, Christopher L. (1997). "Review of Dimethyl Carbonate (DMC) Manufacture and Its Characteristics as a Fuel Additive". Energy Fuels. 11: 2–29. doi:10.1021/ef9600974.
- ^ http://www.epa.gov/ttncaaa1/t1/fact_sheets/voc_exemp01011309.pdf
- ^ Arduengo, Anthony J.; Harlow, Richard L.; Kline, Michael (1991). "A stable crystalline carbene". Journal of the American Chemical Society. 113: 361–363. doi:10.1021/ja00001a054.
- ^ a b Pietro Tundo and Maurizio Selva (2002). "The Chemistry of Dimethyl Carbonate". Acc. Chem. Res. 35 (9): 706–16. doi:10.1021/ar010076f.
- ^ a b Shieh, Wen-Chung (2002). "Nucleophilic Catalysis with 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) for the Esterification of Carboxylic Acids with Dimethyl Carbonate". J. Org. Chem. 67 (7): 2188–2191. doi:10.1021/jo011036s.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Shieh, Wen-Chung; Dell, Steven; Repič, Oljan (2001). "1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) and Microwave-Accelerated Green Chemistry in Methylation of Phenols, Indoles, and Benzimidazoles with Dimethyl Carbonate". Organic Letters. 3 (26): 4279–81. doi:10.1021/ol016949n. PMID 11784197.
Further reading
[edit]- Kreutzberger, Charles B. (2001), "Chloroformates and Carbonates", Kirk-Othmer Encyclopedia of Chemical Technology, New York: John Wiley, doi:10.1002/0471238961.0301180204011312.a01.pub2, ISBN 9780471238966