Dimethyl ether

Dimethyl ether

Names
Systematic IUPAC name Methoxymethane[1]
Other names Demeon Dimethyl oxide Dymel A Methyl ether Mether Wood ether
Identifiers
CAS Registry Number	Y
Abbreviations	DME
Beilstein Reference	1730743
ChEBI	Y
ChEMBL	Y
ChemSpider	Y
EC number	204-065-8
InChI InChI=1S/C2H6O/c1-3-2/h1-2H3 Y Key: LCGLNKUTAGEVQW-UHFFFAOYSA-N Y InChI=1/C2H6O/c1-3-2/h1-2H3 Key: LCGLNKUTAGEVQW-UHFFFAOYAU
Jmol-3D images	Image
KEGG	Y
MeSH
PubChem
RTECS number	PM4780000
SMILES COC
UNII	Y
UN number	1033
Properties
Chemical 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 (68 °F))
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
Safety data sheet	See: data page Oxford MSDS
GHS pictograms
GHS signal word	Danger
GHS hazard statements	H220
GHS precautionary statements	P210, P410+403
EU classification (DSD)	F+
R-phrases	R12
S-phrases	(S2), S9, S16, S33
NFPA 704	4 1 1
Flash point	−41 °C (−42 °F; 232 K)
Autoignition temperature	350 °C (662 °F; 623 K)
Explosive limits	27%
Related compounds
Related ethers	Diethyl ether Polyethylene glycol
Related compounds	Ethanol Methanol
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (: Y/N?)

Dimethyl ether (DME), also known as methoxymethane, is the 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 (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

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
3OCH
3 + SO
3 → (CH
3)
2SO
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)
2O + 2 CO + H₂O → 2 CH₃COOH

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 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

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.^[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, NO_x, 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.

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

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

Refrigerant

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

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

References

http://www.eurammon.coms/default/files/attachments/eurammon12engl.pdf

External links

• The International DME Association

Molecules detected in outer space Molecules Diatomic Aluminium monochloride Aluminium monofluoride Aluminium monoxide Argon hydride Carbon monophosphide Carbon monosulfide Carbon monoxide Carborundum Cyanogen radical Diatomic carbon Fluoromethylidynium Hydrogen chloride Hydrogen fluoride Hydrogen (molecular) Hydroxyl radical Iron(II) oxide Magnesium monohydride cation Methylidyne radical Nitric oxide Nitrogen (molecular) Nitrogen monohydride Nitrogen sulfide Oxygen (molecular) Phosphorus monoxide Phosphorus mononitride Potassium chloride Silicon carbide Silicon mononitride Silicon monoxide Silicon monosulfide Sodium chloride Sodium iodide Sulfur monohydride Sulfur monoxide Titanium oxide Triatomic Aluminium hydroxide Aluminium isocyanide Amino radical Carbon dioxide Carbonyl sulfide CCP radical Chloronium Diazenylium Dicarbon monoxide Disilicon carbide Ethynyl radical Formyl radical Hydrogen cyanide Hydrogen isocyanide (HCN) Hydrogen isocyanide (HNC) Hydrogen sulfide Hydroperoxyl Iron cyanide Isoformyl Magnesium cyanide Magnesium isocyanide Methylene radical N2H+ Nitrous oxide Nitroxyl Ozone Phosphaethyne Potassium cyanide Protonated molecular hydrogen Sodium cyanide Sodium hydroxide Silicon carbonitride c-Silicon dicarbide Silicon naphthalocyanine Sulfur dioxide Thioformyl Thioxoethenylidene Titanium dioxide Tricarbon Water Four atoms Acetylene Ammonia Cyanic acid Cyanoethynyl Cyclopropynylidyne Formaldehyde Fulminic acid HCCN Hydrogen peroxide Hydromagnesium isocyanide Isocyanic acid Isothiocyanic acid Ketenyl Methylene amidogen Methyl radical Propynylidyne Protonated carbon dioxide Protonated hydrogen cyanide Silicon tricarbide Thioformaldehyde Tricarbon monoxide Tricarbon sulfide Thiocyanic acid Five atoms Ammonium Ion Butadiynyl Carbodiimide Cyanamide Cyanoacetylene Cyanoformaldehyde Cyanomethyl Cyclopropenylidene Formic acid Isocyanoacetylene Ketene Methane Methoxy radical Methylenimine Propadienylidene Protonated formaldehyde Protonated formaldehyde Silane Silicon-carbide cluster Six atoms Acetonitrile Cyanobutadiynyl radical E-Cyanomethanimine Cyclopropenone Diacetylene Ethylene Formamide HC4N Ketenimine Methanethiol Methanol Methyl isocyanide Pentynylidyne Propynal Protonated cyanoacetylene Seven atoms Acetaldehyde Acrylonitrile Cyanodiacetylene Ethylene oxide Hexatriynyl radical Methylacetylene Methylamine Methyl isocyanate Vinyl alcohol Eight atoms Acetic acid Aminoacetonitrile Cyanoallene Ethanimine Glycolaldehyde Heptatrienyl radical Hexapentaenylidene Methylcyanoacetylene Methyl formate Propenal Nine atoms Acetamide Cyanohexatriyne Cyanotriacetylene Dimethyl ether Ethanol Methyldiacetylene Octatetraynyl radical Propene Propionitrile Ten atoms or more Acetone Benzene Buckminsterfullerene (C60 fullerene) ("bucky-ball") C70 fullerene Cyanodecapentayne Cyanopentaacetylene Cyanotetra-acetylene Ethylene glycol Ethyl formate Methyl acetate Methyl-cyano-diacetylene Methyltriacetylene Propanal n-Propyl cyanide Pyrimidine Deuterated molecules Ammonia Ammonium ion Formaldehyde Formyl radical Heavy water Hydrogen cyanide Hydrogen deuteride Hydrogen isocyanide Methylacetylene N2D+ Trihydrogen cation Unconfirmed Anthracene Dihydroxyacetone Ethyl methyl ether Glycine Graphene H2NCO+ Linear C5 Naphthalene cation Phosphine Pyrene Silylidine Related Abiogenesis Astrobiology Astrochemistry Atomic and molecular astrophysics Chemical formula Circumstellar envelope Cosmic dust Cosmic ray Cosmochemistry Diffuse interstellar band Extraterrestrial life Extraterrestrial liquid water Forbidden mechanism Helium hydride ion Homochirality Intergalactic dust Interplanetary medium Interstellar medium Iron–sulfur world theory Kerogen Life Molecules in stars Nexus for Exoplanet System Science Organic compound Outer space PAH world hypothesis Panspermia Polycyclic aromatic hydrocarbon (PAH) RNA world hypothesis Spectroscopy Tholin Book:Chemistry Category:Astrochemistry Category:Molecules Portal:Astrobiology Portal:Chemistry