Dimethyl ether

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This article is about dimethyl ether. It is not to be confused with dimethoxyethane.
Dimethyl ether
Skeletal formula of dimethyl ether with all implicit hydrogens shown
Ball and stick model of dimethyl ether
Names
Systematic IUPAC name
Methoxymethane[1]
Other names
Demeon

Dimethyl oxide
Dymel A
Methyl ether
Mether

Wood ether
Identifiers
Abbreviations DME
1730743
115-10-6 YesY
ChEBI CHEBI:28887 YesY
ChEMBL ChEMBL119178 YesY
ChemSpider 7956 YesY
EC number 204-065-8
Jmol-3D images Image
KEGG C11144 YesY
MeSH Dimethyl+ether
PubChem 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 dm−3 (at 20 °C (68 °F))
log P 0.022
Vapor pressure >100 kPa
Dipole moment 1.30 D
Thermochemistry
65.57 J K−1 mol−1
−184.1 kJ mol−1
−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
H220
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)
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 noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY verify (what isYesY/N?)
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 and is being researched on as a future energy option. It is an isomer of ethanol.

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 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

This application consumes several thousand tons of dimethyl ether annually.

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 CH3COOH

Laboratory reagent and solvent[edit]

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[edit]

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

Dimethyl ether 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 dimethyl ether 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 dimethyl ether. 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, dimethyl ether meets even the most stringent emission regulations in Europe (EURO5), U.S. (U.S. 2010), and Japan (2009 Japan).[14] Mobil uses dimethyl ether in their methanol to gasoline process.[citation needed]

Dimethyl ether 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% dimethyl ether. 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 dimethyl ether.

DME Process diagram.jpg

Refrigerant[edit]

Dimethyl ether is considered a refrigerant with ASHRAE refrigerant designation R-E170. Dimethyl ether is also used in refrigerant blends with e.g. ammonia, carbon dioxide, butane and propene.[21]

Safety[edit]

Unlike other alkyl ethers, dimethyl ether resists autoxidation. Dimethyl ether 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 of 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, 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. ^ 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

http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1955&context=iracc

http://www.eurammon.com/sites/default/files/attachments/eurammon12engl.pdf

External links[edit]