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| Dimethyl ether | |
|---|---|
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| IUPAC name | methoxymethane |
| Other names | DME, wood ether dimethyl oxide Demeon, Dymel A |
| Identifiers | |
| CAS number | [115-10-6] |
| RTECS number | PM3780000 |
| SMILES |
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| Properties | |
| Molecular formula | C2H6O CH3OCH3 |
| Molar mass | 46.07 g/mol |
| Appearance | colourless gas with typical smell |
| Density | 1.97 g/L, gas (1.59 × that of air) 668 kg/m3, liquid |
| Melting point |
−138.5 °C (134.6 K)/(−217.3 °F) 242.37 °R |
| Boiling point |
−23 °C (254 K)/(−12.82 °F) 446.85 °R |
| Solubility in water | 328 g/L (20 °C) |
| Structure | |
| Dipole moment | 1.30 D (gas) |
| Hazards | |
| MSDS | External MSDS |
| MSDS | Oxford MSDS |
| Main hazards | highly flammable |
| R-phrases | R12 |
| S-phrases | (S2), S9, S16, S33 |
| Flash point | −41 °C (232.2 K)/(−41.8 °F) 417.87 °R |
| Related compounds | |
| Related ethers | diethyl ether crown ether polyethylene glycol |
| Related compounds | methanol |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
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Dimethyl ether is the organic compound with the formula CH3OCH3. The simplest ether, it is a colourless gas that is a useful precursor to other organic compounds and an aerosol propellant. Dimethyl ether is also promising as a clean-burning hydrocarbon fuel.
Contents |
Production
Dimethyl ether is produced by the dehydration of methanol:
- 2 CH3OH → CH3OCH3 + H2O
Approximately 50,000 tons were produced in 1985 in Western Europe alone.[1] In principle, it could also be manufactured by partial hydrogenation of carbon monoxide, which in turn can be obtained from many sources of hydrocarbons, including biomass.
Applications
Dimethyl ether has two primary applications: as a propellent in aerosol cannisters, and as a precursor to dimethyl sulfate.[1][2] As an aerosol propellent, dimethyl ether is useful as a somewhat polar solvent.
Feedstock
Several thousand tons of dimethyl ether are consumed annually for the production of the methylating agent, dimethyl sulfate, via the reaction with sulfur trioxide:
- CH3OCH3 + SO3 → (CH3O)2SO2
This compound is also converted to acetic acid using technology related to the Monsanto acetic acid process:[1]
- (CH3)2O + 2 CO + H2O → 2 CH3CO2H
Laboratory reagent and solvent
Dimethyl ether is a low-temperature solvent and extraction agent that is used as a solvent in specialised laboratory procedures. Its usefulness is limited by its low boiling point (−23 °C), but the same property facilitates its removal from reaction mixtures. Dimethyl ether is the precursor to the useful alkylating agent, trimethyloxonium tetrafluoroborate.[3]
Fuel
DME is a promising fuel in diesel engines,[4] petrol engines (30% DME / 70% LPG), and gas turbines owing to its high cetane number, which is greater than 55 compared to diesel, which is 40–53.[5] Only moderate modification are needed to convert a diesel engine to burn DME. The simplicity of this short carbon chain compound leads during combustion to very low emissions of particulate matter, NOx, CO. For these reasons as well as being sulfur-free, dimethyl ether meets even the most stringent emission regulations in Europe (EURO5), U.S. (U.S. 2010), and Japan (2009 Japan).[6] DME is being developed as a synthetic biofuel (BioDME), which can be manufactured from lignocellulosic biomass.[7] Currently the EU is considering BioDME in its potential biofuel mix in 2030,citation needed the Volvo Group is the coordinator for the European project BioDME.[8][9] and Mobil is using it in their methanol to gasoline process. The image below illustrates some of processes from various raw materials to DME.
Treating warts
A mixture of dimethyl ether and propane is used in an over-the-counter device to treat warts, by freezing them.[10][11]
Safety
Unlike other alkyl ethers, it resists autoxidation. Dimethyl ether is also relatively non-toxic, although it is highly flammable.
References
- ^ a b c Manfred Müller, Ute Hübsch, “Dimethyl Ether” in Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.
- ^ demeon.com, Akzo Nobel DME
- ^ T. J. Curphey (1988). "Trimethyloxonium tetrafluoroborate". Org. Synth.; Coll. Vol. 6: 1019.
- ^ nycomb.se, Nycomb Chemicals company
- ^ topsoe.com, Haldor Topsoe Chemicals Company
- ^ http://www.japantransport.com/conferences/2006/03/dme_detailed_information.pdf, Conference on the Development and Promotion of Environmentally Friendly Heavy Duty Vehicles such as DME Trucks, Washington DC, March 17, 2006
- ^ http://www.biodme.eu/
- ^ http://www.volvo.com/group/global/en-gb/newsmedia/pressreleases/NewsItemPage.htm?channelId=2184&ItemID=47984&sl=en-gb
- ^ http://www.volvo.com/group/global/en-gb/volvo+group/ourvalues/environment/renewable_fuels/biodme/biodme.htm
- ^ "A Pharmacist's Guide to OTC Therapy: OTC Treatments for Warts" (July 2006).
- ^ http://www.fda.gov/cdrh/pdf3/K030838.pdf
External links
Wikipedia content modification information:
- This page was last modified on 1 October 2008, at 04:20.
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