Dimethyl ether

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Dimethyl ether
Dimethyl ether
File:Dimethyl-ether-3D-balls.png
IUPAC name
methoxymethane
Other names
Carbinic acid anhydride
DME, methyl ether, methoxymethane, wood ether, dimethyl oxide, Demeon, Dymel A
style="background: #F8EABA; text-align: center;" colspan="2" | Identifiers
CAS number 115-10-6 YesY
UN number 1033
RTECS number PM3780000
SMILES Script error: No such module "collapsible list".
style="background: #F8EABA; text-align: center;" colspan="2" | 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

−23.6 °C (254.6 K)/(−12.82 °F) 446.85 °R

Solubility in water 71 g/L (20 °C)
Solubility soluble in acetone, chloroform, ethanol, ether
style="background: #F8EABA; text-align: center;" colspan="2" | Structure
Dipole moment 1.30 D (gas)
style="background: #F8EABA; text-align: center;" colspan="2" | Hazards
MSDS External MSDS
R-phrases R12
S-phrases (S2), S9, S16, S33
Flash point −41 °C (232 K)/(−41.8 °F) 417.87 °R
Autoignition
temperature 		235 C
style="background: #F8EABA; text-align: center;" colspan="2" | Related compounds
Related ethers diethyl ether
crown ether
polyethylene glycol
Related compounds methanol
style="background: #F8EABA; text-align: center;" colspan="2" | Supplementary data page
Structure and
properties 		n, εr, etc.
Thermodynamic
data 		Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 YesY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Dimethyl ether (DME) 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. When combusted, dimethyl ether produces minimal NOx and CO, though HC and soot formation are significant. DME can act as a clean fuel when burned in engines properly optimized for DME.

Production

Today, DME is primarily produced by converting hydrocarbons sourced from natural gas or coal via gasification to synthesis gas (syngas). Synthesis gas is then converted into methanol in the presence of catalyst (usually copper-based), with subsequent methanol dehydration in the presence of a different catalyst (for example, silica-alumina) resulting in the production of DME. As described, this is a two-step (indirect synthesis) process that starts with methanol synthesis and ends with DME synthesis (methanol dehydration).[1] The same process can be conducted using organic waste or biomass. Approximately 50,000 tons were produced in 1985 in Western Europe using the methanol dehydration process.[2] Alternatively, DME can be produced through direct synthesis, using a dual catalyst system that permits both methanol synthesis and dehydration in the same process unit, with no methanol isolation and purification, a procedure that, by eliminating the intermediate methanol synthesis stage, the licensors claim promises efficiency advantages and cost benefits.[1][3]

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. It is worth mentioning that there is a developing one-step liquid-phase process.[1][4]

Applications

The largest use of dimethyl ether is currently (2010) as substitute for propane in LPG used as fuel in household and industry[5]. The largest use of DME for this purpose is in China. Dimethyl ether has two other primary applications: as a propellant in aerosol canisters, and as a precursor to dimethyl sulfate.[2][6] As an aerosol propellant, dimethyl ether is useful as a somewhat polar solvent. It can also be used as a refrigerant.

Feedstock

Several thousand tons of dimethyl ether are consumed annually for the production of the methylating agent, dimethyl sulfate, which entails its reaction with sulfur trioxide:

CH3OCH3 + SO3 → (CH3O)2SO2

Dimethyl ether can also be converted into acetic acid using carbonylation technology related to the Monsanto acetic acid process:[2]

(CH3)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), but the same property facilitates its removal from reaction mixtures. Dimethyl ether is the precursor to the useful alkylating agent, trimethyloxonium tetrafluoroborate.[7]

Fuel

DME is a promising fuel in diesel engines,[8] petrol engines (30% DME / 70% LPG), and gas turbines owing to its high cetane number, which is 55, compared to diesel's, which is 40–53.[9] 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).[10] DME is being developed as a synthetic biofuel (BioDME), which can be manufactured from lignocellulosic biomass.[11] 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.[12][13] and Mobil is using it in their methanol to gasoline process. The image below illustrates some of processes from various raw materials to DME.

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In 2009 a team of university students from Denmark won the Urban Concept/Internal Combustion class at the European Shell Eco Marathon (The Shell Eco Marathon is an unofficial World Championship for mileage) with a vehicle running on 100% DME. The vehicle drove 589 km/liter, fuel equivalent to gasoline with a 50 ccm 2-stroke engine operating by the Diesel principle. As well as winning they beat the old standing record of 306 km/liter, set by the same team in 2007 [14]

Treating warts

A mixture of dimethyl ether and propane is used in an over-the-counter device to treat warts, by freezing them.[15][16]

Safety

Unlike other alkyl ethers, it resists autoxidation. Dimethyl ether is also relatively non-toxic, although it is highly flammable.

References

  1. ↑ 1.0 1.1 1.2 Dimethyl Ether Technology and Markets 07/08-S3 Report, ChemSystems, December 2008.
  2. ↑ 2.0 2.1 2.2 Manfred Müller, Ute Hübsch, “Dimethyl Ether” in Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.
  3. ↑ P.S. Sai Prasad et al., Fuel Processing Technology, 2008, 89, 1281.
  4. ↑ Air Products Technology Offerings
  5. ↑ IDA Fact Sheet DME/LPG Blends 2010 v1
  6. ↑ demeon.com, Akzo Nobel DME
  7. ↑ T. J. Curphey (1988), "Trimethyloxonium tetrafluoroborate", Org. Synth. ; Coll. Vol., 6: 1019  Missing or empty |title= (help)
  8. ↑ nycomb.se, Nycomb Chemicals company
  9. ↑ http://www.topsoe.com/site.nsf/all/BBNN-5PNJ3F?OpenDocument topsoe.com
  10. ↑ 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
  11. ↑ http://www.biodme.eu/
  12. ↑ http://www.volvo.com/group/global/en-gb/newsmedia/pressreleases/NewsItemPage.htm?channelId=2184&ItemID=47984&sl=en-gb
  13. ↑ http://www.volvo.com/group/global/en-gb/volvo+group/ourvalues/environment/renewable_fuels/biodme/biodme.htm
  14. ↑ The Danish Ecocar Team - List of achievements
  15. ↑ "A Pharmacist's Guide to OTC Therapy: OTC Treatments for Warts". July 2006. 
  16. ↑ http://www.fda.gov/cdrh/pdf3/K030838.pdf

External links

de:Dimethylether el:Διμεθυλαιθέρας es:Éter dimetílico fr:Méthoxyméthane ko:다이메틸 에테르 lv:Dimetilēteris hu:Dimetil-éter mk:Диметил етер nl:Dimethylether ja:ジメチルエーテル pl:Eter dimetylowy pt:Dimetil éter ru:Диметиловый эфир fi:Dimetyylieetteri sv:Dimetyleter zh:二甲醚

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