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
Identifiers
Abbreviations DME
CAS number 115-10-6 YesY
PubChem 8254
ChemSpider 7956 YesY
UNII AM13FS69BX YesY
EC number 204-065-8
UN number 1033
KEGG C11144 YesY
MeSH Dimethyl+ether
ChEBI CHEBI:28887 YesY
ChEMBL CHEMBL119178 YesY
RTECS number PM4780000
Beilstein Reference 1730743
Jmol-3D images Image 1
Properties
Molecular formula 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
Solubility in water 71 g dm−3 (at 20 °C)
log P 0.022
Vapor pressure >100 kPa
Dipole moment 1.30 D
Thermochemistry
Specific
heat capacity
C
65.57 J K−1 mol−1
Std enthalpy of
formation
ΔfHo298
−184.1 kJ mol−1
Std enthalpy of
combustion
ΔcHo298
−1.4604 MJ mol−1
Hazards
MSDS External MSDS
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Danger
GHS hazard statements H220
GHS precautionary statements P210, P410+403
EU Index 603-019-00-8
EU classification Extremely Flammable F+
R-phrases R12
S-phrases (S2), S9, S16, S33
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 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine 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)
Explosive limits 27%
Related compounds
Related ethers Diethyl ether

Polyethylene glycol

Related compounds Ethanol

Methanol

Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Dimethyl ether (DME), also known as methoxymethane, is the organic compound with the formula CH
3
OCH
3
. The simplest ether, it is a colourless gas that is a useful precursor to other organic compounds and an aerosol propellant.

Production[edit]

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. It is worth mentioning that there is a developing one-step liquid-phase process.[4][6]

Applications[edit]

The largest use of DME 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

This application consumes several thousand tons of DME annually.

DME 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 CH3COOH

Laboratory reagent and solvent[edit]

DME 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. DME is the precursor to the useful alkylating agent, trimethyloxonium tetrafluoroborate.[7]

Niche applications[edit]

A mixture of DME and propane is used in an over-the-counter device to treat warts, by freezing them.[8][9]

DME is the main constituent of freezer spray, used as a low temperature source in field testing of electronic components.[10]

Research[edit]

Fuel[edit]

Installation of BioDME synthesis towers at Chemrec's pilot facility

A potentially major use of DME is as substitute for propane in LPG used as fuel in household and industry.[11]

It is also a promising fuel in diesel engines,[12] 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.[13] Only moderate modifications 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, and CO. For these reasons as well as being sulfur-free, DME meets even the most stringent emission regulations in Europe (EURO5), U.S. (U.S. 2010), and Japan (2009 Japan).[14] Mobil uses DME in their methanol to gasoline process.[citation needed]

DME is being developed as a synthetic second generation biofuel (BioDME), which can be manufactured from lignocellulosic biomass.[15] Currently the EU is considering BioDME in its potential biofuel mix in 2030;[16] the Volvo Group is the coordinator for the European Community Seventh Framework Programme project BioDME[17][18] where Chemrec's BioDME pilot plant based on black liquor gasification is nearing completion in Piteå, Sweden.[19]

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 [20]

Processes[edit]

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

DME Process diagram.jpg

Refrigerant[edit]

DME is considered a refrigerant with ASHRAE refrigerant designation R-E170. DME is also used in refrigerant blends with e.g. butane and propene.[21]

Safety[edit]

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

References[edit]

  1. ^ "dimethyl ether - PubChem Public Chemical Database". The PubChem Project. USA: National Center for Biotechnology Information. 
  2. ^ a b Record in the GESTIS Substance Database from the IFA
  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 Dimethyl Ether Technology and Markets 07/08-S3 Report, ChemSystems, December 2008.
  5. ^ P.S. Sai Prasad et al., Fuel Processing Technology, 2008, 89, 1281.
  6. ^ Air Products Technology Offerings
  7. ^ T. J. Curphey (1988), "Trimethyloxonium tetrafluoroborate", Org. Synth. ; Coll. Vol. 6: 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. ^ IDA Fact Sheet DME/LPG Blends 2010 v1
  12. ^ nycomb.se, Nycomb Chemicals company
  13. ^ http://www.topsoe.com/site.nsf/all/BBNN-5PNJ3F?OpenDocument topsoe.com
  14. ^ 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
  15. ^ http://www.biodme.eu/
  16. ^ Biofuels in the European Union, 2006
  17. ^ http://www.volvo.com/group/global/en-gb/newsmedia/pressreleases/NewsItemPage.htm?channelId=2184&ItemID=47984&sl=en-gb
  18. ^ http://www.volvo.com/group/global/en-gb/volvo+group/ourvalues/environment/renewable_fuels/biodme/biodme.htm
  19. ^ Chemrec press release September 9, 2010
  20. ^ The Danish Ecocar Team - List of achievements
  21. ^ http://www.ashrae.org/technology/page/1933#et ASHRAE list of refrigerants

External links[edit]