|Preferred IUPAC name
3D model (Jmol)
|Molar mass||46.07 g·mol−1|
|Density||2.1146 kg/m3 (gas, 0 °C, 1013 mbar)
0.735 g/mL (liquid, -25 °C)
|Melting point||−141 °C; −222 °F; 132 K|
|Boiling point||−24 °C; −11 °F; 249 K|
|71 g/L (at 20 °C (68 °F))|
|Vapor pressure||>100 kPa|
|65.57 J K−1 mol−1|
Std enthalpy of
|−184.1 kJ mol−1|
Std enthalpy of
|−1.4604 MJ mol−1|
|Safety data sheet||See: data page
|GHS signal word||Danger|
EU classification (DSD)
|S-phrases||(S2), S9, S16, S33|
|Flash point||−41 °C (−42 °F; 232 K)|
|350 °C (662 °F; 623 K)|
|Supplementary data page|
|Refractive index (n),
Dielectric constant (εr), etc.
|UV, IR, NMR, MS|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Dimethyl ether (DME), also known as methoxymethane, is the organic compound with the formula CH3OCH3, simplified to C2H6O. The simplest ether, it is a colorless gas that is a useful precursor to other organic compounds and an aerosol propellant that is currently being demonstrated for use in a variety of fuel applications. It is an isomer of ethanol.
- 2 CH3OH → (CH3)2O + H2O
The required methanol is obtained from synthesis gas (syngas). In principle, the methanol could be obtained from organic waste or biomass. Other possible improvements call for a dual catalyst system that permits both methanol synthesis and dehydration in the same process unit, with no methanol isolation and purification.
Both the one-step and two-step processes above are commercially available. Currently, there is more widespread application of the two-step process, since it is relatively simple and start-up costs are relatively low. There is also a one-step liquid-phase process in development.
3 + SO
3 → (CH
2O + 2 CO + H2O → 2 CH3CO2H
Laboratory reagent and solvent
Dimethyl ether is a low-temperature solvent and extraction agent, applicable to specialised laboratory procedures. Its usefulness is limited by its low boiling point (−23 °C (−9 °F)), but the same property facilitates its removal from reaction mixtures. Dimethyl ether is the precursor to the useful alkylating agent, trimethyloxonium tetrafluoroborate.
Dimethyl ether is the main constituent of "freeze spray", a spot-coolant used in field testing of electronic components. In this role it has supplanted halocarbon compounds (Freon), which have been suspected of contributing to ozone depletion in the Earth's atmosphere.
It is also a promising fuel in diesel engines, petrol engines (30% DME / 70% LPG), and gas turbines. For diesel engines, an advantage is the high cetane number of 55, compared to that of diesel fuel from petroleum, which is 40–53. Only moderate modifications are needed to convert a diesel engine to burn dimethyl ether. The simplicity of this short carbon chain compound leads during combustion to very low emissions of particulate matter, NOx, and 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). Mobil uses dimethyl ether in their methanol to gasoline process.
Dimethyl ether is being developed as a synthetic second generation biofuel (BioDME), which can be manufactured from lignocellulosic biomass. Currently the EU is considering BioDME in its potential biofuel mix in 2030; the Volvo Group is the coordinator for the European Community Seventh Framework Programme project BioDME where Chemrec's BioDME pilot plant based on black liquor gasification is nearing completion in Piteå, Sweden.
At the European Shell Eco Marathon, an unofficial World Championship for mileage, vehicle running on 100% dimethyl ether drove 589 km/liter, fuel equivalent to gasoline with a 50 cc 2-stroke Diesel engine. As well as winning they beat the old standing record of 306 km/liter, set by the same team in 2007.
The image below illustrates some of processes from various raw materials to dimethyl ether.
Unlike other alkyl ethers, dimethyl ether resists autoxidation. Dimethyl ether is also relatively non-toxic, although it is highly flammable.
- Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
- Manfred Müller, Ute Hübsch, “Dimethyl Ether” in Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a08_541
- Dimethyl Ether Technology and Markets 07/08-S3 Report, ChemSystems, December 2008.
- P.S. Sai Prasad et al., Fuel Processing Technology, 2008, 89, 1281.
- Air Products Technology Offerings
- T. J. Curphey (1988). "Trimethyloxonium tetrafluoroborate". Org. Synth.; Coll. Vol., 6, p. 1019
- "A Pharmacist's Guide to OTC Therapy: OTC Treatments for Warts". July 2006.
- IDA Fact Sheet DME/LPG Blends 2010 v1
- nycomb.se, Nycomb Chemicals company
- http://www.topsoe.com/site.nsf/all/BBNN-5PNJ3F?OpenDocument topsoe.com
- 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
- Biofuels in the European Union, 2006
- Chemrec press release September 9, 2010
- The Danish Ecocar Team - List of achievements
- http://www.ashrae.org/technology/page/1933#et ASHRAE list of refrigerants