| |||
| Names | |||
|---|---|---|---|
| Preferred IUPAC name Methoxymethane[1] | |||
| Other names | |||
| Identifiers | |||
| |||
3D model (JSmol) | |||
| Abbreviations | DME | ||
| 1730743 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
| ||
| ECHA InfoCard | 100.003.696 | ||
| EC Number |
| ||
| KEGG |
| ||
| MeSH | Dimethyl+ether | ||
| RTECS number |
| ||
| UNII | |||
| UN number | 1033 | ||
| |||
| |||
| Properties | |||
| C2H6O | |||
| Molar mass | 46.069 g·mol−1 | ||
| Appearance | Colorless gas | ||
| Odor | Ethereal[2] | ||
| Density | 2.1146 kg m−3 (gas, 0 °C, 1013 mbar)[2] 0.735 g/mL (liquid, −25 °C)[2] | ||
| Melting point | −141 °C; −222 °F; 132 K | ||
| Boiling point | −24 °C; −11 °F; 249 K | ||
| 71 g/L (at 20 °C (68 °F)) | |||
| logP | 0.022 | ||
| Vapor pressure | 592.8 kPa[3] | ||
| −26.3×10−6 cm3 mol−1 | |||
| 1.30 D | |||
| Thermochemistry | |||
| 65.57 J K−1 mol−1 | |||
Std enthalpy of formation(ΔfH⦵298) | −184.1 kJ mol−1 | ||
Std enthalpy of combustion(ΔcH⦵298) | −1460.4 kJ mol−1 | ||
| Hazards | |||
| GHS labelling:[4] | |||
 | |||
| Danger | |||
| H220 | |||
| P210,P377,P381,P403 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | −41 °C (−42 °F; 232 K) | ||
| 350 °C (662 °F; 623 K) | |||
| Explosive limits | 27 % | ||
| Safety data sheet (SDS) | ≥99% Sigma-Aldrich | ||
| Related compounds | |||
Relatedethers | Diethyl ether | ||
Related compounds | Ethanol | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Dimethyl ether (DME; also known asmethoxymethane) is theorganic compound with the formula CH3OCH3, (sometimes ambiguously simplified to C2H6O as it is anisomer ofethanol). The simplestether, 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.
Dimethyl ether was first synthesised byJean-Baptiste Dumas andEugene Péligot in 1835 by distillation of methanol and sulfuric acid.[5]
Approximately 50,000 tons were produced in 1985 in Western Europe bydehydration ofmethanol:[6]
The required methanol is obtained from synthesis gas (syngas).[7] 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.[7][8]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.[7][9]
Dimethyl ether is a syntheticsecond generation biofuel (BioDME), which can be produced fromlignocellulosic biomass.[10] The EU is considering BioDME in its potential biofuel mix in 2030;[11] It can also be made frombiogas ormethane from animal, food, and agricultural waste,[12][13] or even fromshale gas ornatural gas.[14]
TheVolvo Group is the coordinator for theEuropean CommunitySeventh Framework Programme project BioDME[15][16] whereChemrec's BioDME pilot plant is based onblack liquorgasification inPiteå,Sweden.[17]
The largest use of dimethyl ether is as the feedstock for the production of the methylating agent,dimethyl sulfate, which entails its reaction withsulfur trioxide:
Dimethyl ether can also be converted intoacetic acid usingcarbonylation technology related to theMonsanto acetic acid process:[6]
Dimethyl ether is a low-temperature solvent and extraction agent, applicable to specialised laboratory procedures. Its usefulness is limited by its lowboiling point (−23 °C (−9 °F)), but the same property facilitates its removal from reaction mixtures. Dimethyl ether is the precursor to the usefulalkylating agent,trimethyloxonium tetrafluoroborate.[18]
A mixture of dimethyl ether andpropane is used in some over-the-counter "freeze spray" products to treatwarts byfreezing them.[19][20] In this role, it has supplanted halocarbon compounds (Freon).
Dimethyl ether is also a component of certain high temperature"Map-Pro" blowtorch gas blends, supplanting the use ofmethyl acetylene andpropadiene mixtures.[21]
Dimethyl ether is also used as a propellant in aerosol products. Such products include hair spray, bug spray and some aerosol glue products.
A potentially major use of dimethyl ether is as substitute forpropane inLPG used as fuel in household and industry.[22] Dimethyl ether can also be used as a blendstock in propaneautogas.[23]
It is also a promising fuel indiesel engines,[24] andgas turbines. For diesel engines, an advantage is the highcetane number of 55, compared to that ofdiesel fuel from petroleum, which is 40–53.[25] Only moderate modifications are needed to convert a diesel engine to burn dimethyl ether. The simplicity of this short carbon chain compound leads to very low emissions of particulate matter during combustion. 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).[26]
At theEuropean Shell Eco Marathon, an unofficial World Championship for mileage, a vehicle running on 100 % dimethyl ether drove 589 km/L (0.170 L per 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/L (0.327 L per 100 km), set by the same team in 2007.[27]
To study the dimethyl ether for the combustion process a chemical kinetic mechanism[28] is required which can be used for Computational fluid dynamics calculation.
Dimethyl ether is arefrigerant withASHRAE refrigerant designation R-E170.[29] It is also used in refrigerant blends with e.g.ammonia,carbon dioxide,butane andpropene.Dimethyl ether was the first refrigerant. In 1876, the French engineerCharles Tellier bought the ex-Elder-Dempster a 690 tons cargo shipEboe and fitted a methyl-etherrefrigerating plant of his design. The ship was renamedLe Frigorifique and successfully imported a cargo of refrigerated meat fromArgentina. However the machinery could be improved and in 1877 another refrigerated ship calledParaguay with a refrigerating plant improved byFerdinand Carré was put into service on the South American run.[30]
Unlike other alkyl ethers, dimethyl ether resistsautoxidation.[31] Dimethyl ether is also relatively non-toxic, although it is highly flammable. On July 28, 1948, aBASF factory inLudwigshafen suffered an explosion after 30 tonnes of dimethyl ether leaked from a tank and ignited in the air. 200 people died, and a third of the industrial plant was destroyed.[32]
| Temperature (K) | Pressure (kPa) |
|---|---|
| 233.128 | 54.61 |
| 238.126 | 68.49 |
| 243.157 | 85.57 |
| 248.152 | 105.59 |
| 253.152 | 129.42 |
| 258.16 | 157.53 |
| 263.16 | 190.44 |
| 268.161 | 228.48 |
| 273.153 | 272.17 |
| 278.145 | 321.87 |
| 283.16 | 378.66 |
| 288.174 | 443.57 |
| 293.161 | 515.53 |
| 298.172 | 596.21 |
| 303.16 | 687.37 |
| 305.16 | 726.26 |
| 308.158 | 787.07 |
| 313.156 | 897.59 |
| 316.154 | 968.55 |
| 318.158 | 1018.91 |
| 323.148 | 1152.35 |
| 328.149 | 1298.23 |
| 333.157 | 1457.5 |
| 333.159 | 1457.76 |
| 338.154 | 1631.01 |
| 343.147 | 1818.8 |
| 348.147 | 2022.45 |
| 353.146 | 2242.74 |
| 353.158 | 2243.07 |
| 358.145 | 2479.92 |
| 363.148 | 2735.67 |
| 368.158 | 3010.81 |
| 373.154 | 3305.67 |
| 378.15 | 3622.6 |
| 383.143 | 3962.25 |
| 388.155 | 4331.48 |
| 393.158 | 4725.02 |
| 398.157 | 5146.82 |
| 400.378 | 5355.8 |
{{cite web}}: CS1 maint: archived copy as title (link){{cite web}}: CS1 maint: archived copy as title (link){{cite web}}: CS1 maint: archived copy as title (link),Conference on the Development and Promotion of Environmentally Friendly Heavy Duty Vehicles such as DME Trucks, Washington DC, March 17,2006| International | |
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| National | |
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