Dimethyl ether

Structural formula
General
Surname	Dimethyl ether
other names	Methoxymethane ( IUPAC ); Wooden ether; Methyl ether; Methyl oxide; DME;
Molecular formula	C 2 H 6 O
Brief description	colorless gas with an ethereal odor
External identifiers / databases
EC number	204-065-8
ECHA InfoCard	100.003.696
PubChem	8254
Wikidata	Q408050
properties
Molar mass	46.06 g mol −1
Physical state	gaseous
density	2.1146 kg m −3 (gas density at 0 ° C, 1013 hPa) ; 1.967 kg m −3 (gas density at 15 ° C) ; 0.7354 g cm −3 (liquid at boiling point) ;
Melting point	−141.5 ° C
boiling point	−24.8 ° C
Vapor pressure	5.1 bar (20 ° C); 6.9 bar (30 ° C); 11.4 bar (50 ° C); 18.1 bar (70 ° C);
solubility	little in water (70 g l −1 at 20 ° C)
Dipole moment	1.30 D (4.3 x 10 -30 C · m )
safety instructions
H and P phrases	H: 220-280
	P: 210-377-381-403
MAK	DFG / Switzerland: 1000 ml m −3 or 1910 mg m −3
Global warming potential	1 (based on 100 years)
Thermodynamic properties
ΔH f 0	−184.1 kJ / mol
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Dimethyl ether is the simplest ether and a dialkyl ether . It contains two methyl groups as organic residues. Dimethylether is polar and is used in liquid form as a solvent .

properties

Dimethyl ether is (under normal conditions) a colorless, extremely flammable, narcotic gas. The compound boils at −24 ° C. The heat of evaporation at the boiling point is 21.51 kJ / mol. Up to 34% is soluble in water under pressure.

Thermodynamic properties

According to Antoine, the vapor pressure function results from log ₁₀ (P) = A− (B / (T + C)) (P in bar, T in K) with A = 4.11475, B = 894.669 and C = −30.604 in the temperature range from 194.93 to 248.24 K. The critical values are 126.9 ° C for the critical temperature , 53.7 bar for the critical pressure and 0.271 g · cm ⁻³ for the critical density .

Safety-related parameters

Dimethyl ether forms highly flammable vapor-air mixtures. The compound has a flash point of −42 ° C. The explosion range is between 2.8% by volume as the lower explosion limit (LEL) and 24.4% by volume as the upper explosion limit (UEL). The maximum explosion pressure is 9.8 bar. The limit gap width was determined to be 0.84 mm (50 ° C). This results in an assignment to explosion group IIB. The ignition temperature is 240 ° C. The substance therefore falls into temperature class T3.

Manufacturing

It can be obtained, for example, by acid-catalyzed condensation from 2 molecules of methanol (with elimination of water ):

{\ displaystyle \ mathrm {2 \; CH_ {3} OH \ rightarrow CH_ {3} \! - \! O \! - \! CH_ {3} + H_ {2} O}}

Dimethyl ether is a by-product of methanol synthesis and is usually produced directly from synthesis gas . Coal , natural and biogas as well as syngas from biomass gasification are of particular interest as sources for the synthesis gas .

The synthesis is a two-stage process in which methanol is first produced with the help of appropriate catalysts (usually CuO / ZnO / Al ₂ O ₃ ) at temperatures of 270 ° C and a pressure of 5 to 10 MPa, which is dehydrated in a second step in the presence of an acid catalyst (usually aluminum) within the same process. The separated dimethyl ether still contains small amounts of methanol and water.

use

Highly pure dimethyl ether is widely used as a propellant z. B. in hairspray and paint spray. Technical dimethyl ether is an alternative to liquid gas with excellent burning properties. An azeotropic mixture of dimethyl ether and ammonia results in the refrigerant R723.

A large proportion of the dimethyl ether produced is converted with sulfur trioxide (SO ₃ ) to dimethyl sulfate (C ₂ H ₆ O ₄ S), which is required as the basis for a number of chemical processes and products.

{\ displaystyle \ mathrm {SO_ {3} + CH_ {3} \! - \! O \! - \! CH_ {3} \ rightarrow (CH_ {3}) _ {2} SO_ {4}}}

Until the 1980s, this was the main use of dimethyl ether; in 1998, around 15,000 t of the 50,000 t produced in Central Europe were converted into dimethyl sulfate.

Dimethyl ether is also an intermediate product for the production of alkenes such as ethene (ethylene) and propene (propylene) from methanol or natural gas in the so-called methanol-to-olefins technology, which is an alternative to the processes currently used from crude oil ("steam cracking") ) was developed.

DME as a fuel

With a cetane number of 55 to 60, dimethyl ether can be used in diesel engines as a substitute for diesel fuel . Slight modifications to the engine are required, mainly affecting the injection pump , as well as the installation of a pressure tank, similar to LPG . Dimethyl ether burns very cleanly in diesel engines without forming soot. The calorific value is 28.4 MJ / kg.

According to the biofuel directive 2003-30-EG, dimethyl ether is considered a biofuel if it is "made from biomass and is intended for use as biofuel" and is intended to replace liquid gas in the long term. As a raw material for the production of synthesis gas to the black liquor used in the paper and pulp industry. A first factory for the production of organically produced dimethyl ether was built in 2012 in Piteå , Sweden .

bad luck

In the explosion of a tank car filled with dimethyl ether on the BASF premises in Ludwigshafen am Rhein on July 28, 1948, a total of 207 people died and 3818 were injured. 3,122 buildings were affected.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t Entry on dimethyl ether in the GESTIS substance database of the IFA , accessed on March 21, 2018(JavaScript required) .
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Permittivity (Dielectric Constant) of Gases, pp. 6-188.
↑ Entry on dimethyl ether in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 115-10-6 or dimethyl ether ), accessed on November 2, 2015.
↑ P. Forster, P., V. Ramaswamy et al .: Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge and New York 2007, p. 213, (PDF)
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-22.
^ V. Majer, V. Svoboda: Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation. Blackwell Scientific Publications, Oxford 1985, p. 300.
↑ RM Kennedy, M. Sagenkahn, JG Aston: The heat capacity and entropy, heats of fusion and vaporization, and the vapor pressure of dimethyl ether. The density of gaseous dimethyl ether. In: J. Am. Chem. Soc. 63, 1941, pp. 2267-2272, doi : 10.1021 / ja01853a068 .
↑ ^a ^b ^c ^d ^e E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.
↑ ^a ^b Manfred Müller, Ute Hübsch: Dimethyl Ether. In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH, Weinheim 2012, doi : 10.1002 / 14356007.a08_541 .
↑ Grillo-Werke AG | DIMETHYL ETHER . ( grillo.de [accessed November 8, 2018]).
↑ Tao Ren, Martin K. Patel, Kornelis Blok: Steam cracking and methane to olefins: Energy use, CO ₂ emissions and production costs. In: Energy. 33, 2008.
↑ Directive 2003/30 / EC of the European Parliament and the Council of May 8, 2003 on the promotion of the use of biofuels or other renewable fuels in the transport sector
^ Peter Fairly: Taking Pulp to the Pump. In: Technology Review. December 12, 2008.
↑ Elisabeth Kempemo: Perfectly clean BioDME flowing steadily . In: ChemrecNews. May 2012, accessed September 10, 2012.

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t Entry on dimethyl ether in the GESTIS substance database of the IFA , accessed on March 21, 2018(JavaScript required) .

[CRC90_6_188-2] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Permittivity (Dielectric Constant) of Gases, pp. 6-188.

[CLP_100.003.696-3] Entry on dimethyl ether in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[4] Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 115-10-6 or dimethyl ether ), accessed on November 2, 2015.

[5] P. Forster, P., V. Ramaswamy et al .: Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge and New York 2007, p. 213, (PDF)

[CRC90_5_22-6] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-22.

[7] V. Majer, V. Svoboda: Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation. Blackwell Scientific Publications, Oxford 1985, p. 300.

[Kennedy-8] RM Kennedy, M. Sagenkahn, JG Aston: The heat capacity and entropy, heats of fusion and vaporization, and the vapor pressure of dimethyl ether. The density of gaseous dimethyl ether. In: J. Am. Chem. Soc. 63, 1941, pp. 2267-2272, doi : 10.1021 / ja01853a068 .

[Brandes-9] E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.

[Ullmann_DME-10] Manfred Müller, Ute Hübsch: Dimethyl Ether. In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH, Weinheim 2012, doi : 10.1002 / 14356007.a08_541 .

[11] Grillo-Werke AG | DIMETHYL ETHER . ( grillo.de [accessed November 8, 2018]).

[Ren-12] Tao Ren, Martin K. Patel, Kornelis Blok: Steam cracking and methane to olefins: Energy use, CO ₂ emissions and production costs. In: Energy. 33, 2008.

[13] Directive 2003/30 / EC of the European Parliament and the Council of May 8, 2003 on the promotion of the use of biofuels or other renewable fuels in the transport sector

[14] Peter Fairly: Taking Pulp to the Pump. In: Technology Review. December 12, 2008.

[15] Elisabeth Kempemo: Perfectly clean BioDME flowing steadily . In: ChemrecNews. May 2012, accessed September 10, 2012.