|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||46.069 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|
Heat capacity (C)
|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|
|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.
The required methanol is obtained from synthesis gas (syngas). 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. The two-step process is relatively simple and start-up costs are relatively low. A one-step liquid-phase process is in development.
Dimethyl ether is a synthetic second generation biofuel (BioDME), which can be produced from lignocellulosic biomass. The EU is considering BioDME in its potential biofuel mix in 2030; It can also be made from biogas or methane from animal, food, and agricultural waste, or even from shale gas or natural gas.
The Volvo Group is the coordinator for the European Community Seventh Framework Programme project BioDME where Chemrec's BioDME pilot plant is based on black liquor gasification in Piteå, Sweden.
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.
A mixture of dimethyl ether and propane is used in some over-the-counter "freeze spray" products to treat warts, by freezing them. In this role, it has supplanted halocarbon compounds (Freon).
Dimethyl ether is also used as a propellant in aerosol products. Such products include hair spray, bug spray and some aerosol glue products.
It is also a promising fuel in diesel engines, 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. 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).
At the European Shell Eco Marathon, an unofficial World Championship for mileage, vehicle running on 100% dimethyl ether drove 589 km/liter (169.8 cm3 /100 km), fuel equivalent to gasoline with a 50 cm3 displacement 2-stroke engine. As well as winning they beat the old standing record of 306 km/liter (326.8 cm3/100 km), set by the same team in 2007.
Dimethyl ether is a refrigerant with ASHRAE refrigerant designation R-E170. It is also used in refrigerant blends with e.g. ammonia, carbon dioxide, butane and propene. Dimethyl ether was the first refrigerant, in 1876, French engineer Charles Tellier bought the ex-Elder-Dempster a 690 tons cargo ship Eboe and fitted a Methyl-ether refrigerating plant of his design. The ship was renamed Le Frigorifique and successfully imported a cargo of refrigerated meat from Argentina. However the machinery could be improved and in 1877 another refrigerated ship called Paraguay with a refrigerating plant improved by Ferdinand Carré was put into service on the South American run.