Dimethyl ether

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Dimethyl ether
Skeletal formula of dimethyl ether with all implicit hydrogens shown
Ball and stick model of dimethyl ether
Names
Preferred IUPAC name
Methoxymethane[1]
Other names
Dimethyl ether[1]
R-E170
Demeon
Dimethyl oxide
Dymel A
Methyl ether
Mether
Wood ether
Identifiers
  • 115-10-6 YesY
3D model (JSmol)
  • Interactive image
Abbreviations DME
1730743
ChEBI
  • CHEBI:28887 YesY
ChEMBL
  • ChEMBL119178 YesY
ChemSpider
  • 7956 YesY
ECHA InfoCard 100.003.696
EC Number 204-065-8
KEGG
  • C11144 YesY
MeSH Dimethyl+ether
PubChem CID
  • 8254
RTECS number PM4780000
UNII
  • AM13FS69BX YesY
UN number 1033
Properties
C2H6O
Molar mass 46.07 g·mol−1
Appearance Colorless gas
Odor Typical
Density 2.1146 kg/m3 (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))
log P 0.022
Vapor pressure >100 kPa
-26.3·10−6 cm3/mol
1.30 D
Thermochemistry
65.57 J K−1 mol−1
−184.1 kJ mol−1
−1.4604 MJ mol−1
Hazards
Safety data sheet See: data page
≥99% Sigma-Aldrich
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Danger
H220
P210, P410+403
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point −41 °C (−42 °F; 232 K)
350 °C (662 °F; 623 K)
Explosive limits 27%
Related compounds
Related ethers
Diethyl ether

Polyethylene glycol

Related compounds
Ethanol

Methanol

Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Thermodynamic
data
Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYNo ?)
Infobox references

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.

Production

Approximately 50,000 tons were produced in 1985 in Western Europe by dehydration of methanol:[3]

2 CH3OH → (CH3)2O + H2O

The required methanol is obtained from synthesis gas (syngas).[4] 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.[4][5]

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.[4][6]

Applications

The largest use of dimethyl ether is as the feedstock for the production of the methylating agent, dimethyl sulfate, which entails its reaction with sulfur trioxide:

CH
3
OCH
3
+ SO
3
(CH
3
)
2
SO
4

Dimethyl ether can also be converted into acetic acid using carbonylation technology related to the Monsanto acetic acid process:[3]

(CH
3
)
2
O
+ 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.[7]

Niche applications

A mixture of dimethyl ether and propane is used in some over-the-counter "freeze spray" products to treat warts, by freezing them.[8][9]

Dimethyl ether is the main constituent in some industrial "freeze spray" spot-coolants used in field testing of electronic components.[10] In this role it has supplanted halocarbon compounds (Freon), which have been suspected of contributing to ozone depletion in the Earth's atmosphere.

Dimethyl ether is also a component of certain high temperature "MAP-plus" blowtorch gas blends, supplanting the use of methyl acetylene and propadiene mixtures.[11]

Dimethyl ether is also used as a propellant in aerosol products. Such products include hair spray, bug spray and some aerosol glue products.

Research

Fuel

Installation of BioDME synthesis towers at Chemrec's pilot facility

A potentially major use of dimethyl ether is as substitute for propane in LPG used as fuel in household and industry.[12]

It is also a promising fuel in diesel engines,[13] 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.[14] 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).[15]

Dimethyl ether is being developed as a synthetic second generation biofuel (BioDME), which can be manufactured from lignocellulosic biomass.[16] Currently the EU is considering BioDME in its potential biofuel mix in 2030;[17] the Volvo Group is the coordinator for the European Community Seventh Framework Programme project BioDME[18][19] where Chemrec's BioDME pilot plant based on black liquor gasification is nearing completion in Piteå, Sweden.[20]

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 engine. As well as winning they beat the old standing record of 306 km/liter, set by the same team in 2007.[21]

Processes

The image below illustrates some of processes from various raw materials to dimethyl ether.

DME Process diagram.jpg

Refrigerant

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.[22]

Safety

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

References

  1. ^ a b Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 703. doi:10.1039/9781849733069-00648. ISBN 978-0-85404-182-4. 
  2. ^ a b Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  3. ^ a b Manfred Müller, Ute Hübsch, “Dimethyl Ether” in Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a08_541
  4. ^ a b c "CHEMSYSTEMS.COM" (PDF). www.chemsystems.com. Retrieved 1 April 2018. 
  5. ^ P.S. Sai Prasad et al., Fuel Processing Technology, 2008, 89, 1281.
  6. ^ "Air Products Technology Offerings". airproducts.com. Retrieved 1 April 2018. 
  7. ^ T. J. Curphey (1988). "Trimethyloxonium tetrafluoroborate". Organic Syntheses. ; Collective Volume, 6, p. 1019 
  8. ^ "A Pharmacist's Guide to OTC Therapy: OTC Treatments for Warts". July 2006. 
  9. ^ http://www.fda.gov/cdrh/pdf3/K030838.pdf
  10. ^ http://www.electrolube.com/products/msds/044FRE.pdf
  11. ^ http://images.toolbank.com/downloads/cossh/0482.pdf
  12. ^ "IDA Fact Sheet DME/LPG Blends 2010 v1" (PDF). aboutdme.org. Retrieved 1 April 2018. 
  13. ^ nycomb.se, Nycomb Chemicals company Archived 2008-06-03 at the Wayback Machine.
  14. ^ "Archived copy". Archived from the original on 2007-10-08. Retrieved 2011-11-04.  topsoe.com
  15. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2009-01-07. Retrieved 2011-11-04. , Conference on the Development and Promotion of Environmentally Friendly Heavy Duty Vehicles such as DME Trucks, Washington DC, March 17, 2006
  16. ^ "BioDME". www.biodme.eu. Retrieved 1 April 2018. 
  17. ^ "Biofuels in the European Union, 2006" (PDF). europa.eu. Retrieved 1 April 2018. 
  18. ^ "Archived copy". Archived from the original on 2009-05-25. Retrieved 2011-11-04. 
  19. ^ "Volvo Group - Driving prosperity through transport solutions". www.volvo.com. Retrieved 1 April 2018. 
  20. ^ Chemrec press release September 9, 2010 Archived June 12, 2017, at the Wayback Machine.
  21. ^ "The Danish Ecocar Team - List of achievements". dtu.dk. Retrieved 1 April 2018. 
  22. ^ http://www.ashrae.org/technology/page/1933#et ASHRAE list of refrigerants

External links

  • The International DME Association
  • NOAA site for NFPA 704
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