Difference between revisions of "Dimethyl ether"

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| pKa =  
 
| pKa =  
 
| pKb =  
 
| pKb =  
−
| Solubility = 71 g/l (at 20 °C)
+
| Solubility = 7.1 g/ 100 ml (at 20 °C)
 
| SolubleOther = Soluble in [[acetone]], [[chloroform]], [[ethanol]], [[isopropanol]], [[methanol]]
 
| SolubleOther = Soluble in [[acetone]], [[chloroform]], [[ethanol]], [[isopropanol]], [[methanol]]
 
| Solvent =  
 
| Solvent =  
−
| VaporPressure = >100 kPa
+
| VaporPressure = 4450 mmHg at 25 °C
 
   }}
 
   }}
 
| Section3 = {{Chembox Structure
 
| Section3 = {{Chembox Structure
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| Section4 = {{Chembox Thermochemistry
 
| Section4 = {{Chembox Thermochemistry
 
| DeltaGf =  
 
| DeltaGf =  
−
| DeltaHc = −1.4604 MJ·mol<sup>−1</sup>
+
| DeltaHc = −1,460.4 kJ·mol<sup>−1</sup>
 
| DeltaHf = −184.1 kJ·mol<sup>−1</sup>
 
| DeltaHf = −184.1 kJ·mol<sup>−1</sup>
 
| Entropy =  
 
| Entropy =  
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   }}
 
   }}
 
| Section6 = {{Chembox Hazards
 
| Section6 = {{Chembox Hazards
−
| AutoignitionPt = 350 °C
+
| AutoignitionPt = 350 °C (662 °F; 623 K)
−
| ExploLimits = 27%
+
| ExploLimits = 3.4-27 %
 
| ExternalMSDS = [http://www.praxair.com/-/media/praxairus/documents/sds/dimethyl-ether-c2h6o-safety-data-sheet-sds-p4589.pdf?la=en Praxair]
 
| ExternalMSDS = [http://www.praxair.com/-/media/praxairus/documents/sds/dimethyl-ether-c2h6o-safety-data-sheet-sds-p4589.pdf?la=en Praxair]
−
| FlashPt = −41 °C
+
| FlashPt = −41 °C (-41.8 °F; 232 K)
 
| LD50 =  
 
| LD50 =  
 
| LC50 =  
 
| LC50 =  
−
| MainHazards =  
+
| MainHazards = Flammable
 
| NFPA-F =  
 
| NFPA-F =  
 
| NFPA-H =  
 
| NFPA-H =  
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Dimethyl ether is flammable and will burn when ignited in an oxygen atmosphere.
 
Dimethyl ether is flammable and will burn when ignited in an oxygen atmosphere.
  
−
Dimethyl ether can be carbonylated to [[acetic acid]]:
+
: CH<sub>3</sub>-O-CH<sub>3</sub> + 3 O<sub>2</sub> →  2 CO<sub>2</sub> + 3 H<sub>2</sub>O
−
: CH<sub>3</sub>-O-CH<sub>3</sub> + 2 CO + H<sub>2</sub>O →  2 CH<sub>3</sub>-COOH
+
  
−
This reaction proceeds under high pressure.
+
Dimethyl ether can be carbonylated to [[acetic acid]]. This reaction proceeds under high pressure:
 +
 
 +
: CH<sub>3</sub>-O-CH<sub>3</sub> + 2 CO + H<sub>2</sub>O → 2 CH<sub>3</sub>-COOH
 +
 
 +
Reaction with [[sulfur trioxide]] yields [[dimethyl sulfate]]:
 +
 
 +
: CH<sub>3</sub>-O-CH<sub>3</sub> + SO<sub>3</sub> → (CH<sub>3</sub>)<sub>2</sub>SO<sub>4</sub>
  
 
===Physical===
 
===Physical===
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==Preparation==
 
==Preparation==
−
Dimethyl ether can be prepared by dehydration of [[methanol]], in the presence of a catalyst, such as conc. [[sulfuric acid]]. The resulting gaseous dimethyl ether is then dried and stored either dissolved in a solvent or compressed in a gas tube.
+
Dimethyl ether can be prepared by dehydration of [[methanol]], in the presence of a catalyst, such as conc. [[sulfuric acid]].
 +
 
 +
:2 CH<sub>3</sub>OH → (CH<sub>3</sub>)<sub>2</sub>O + H<sub>2</sub>O
 +
 
 +
The resulting gaseous dimethyl ether is then purified, dried and stored either dissolved in a solvent or compressed in a gas tube/lecture bottle.
  
 
==Projects==
 
==Projects==

Latest revision as of 13:26, 26 August 2023

Dimethyl ether
Names
IUPAC name
Methoxymethane
Other names
Demeon
Dimethyl oxide
Dymel A
Mether
Methyl ether
Wood ether
Identifiers
Jmol-3D images Image
Properties
C2H6O
CH3OCH3
Molar mass 46.07 g/mol
Appearance Colorless gas
Odor Ether-like
Density 1.91855 g/cm3 (at 25°C)
Melting point −141 °C (−222 °F; 132 K)
Boiling point −24 °C (−11 °F; 249 K)
7.1 g/ 100 ml (at 20 °C)
Solubility Soluble in acetone, chloroform, ethanol, isopropanol, methanol
Vapor pressure 4450 mmHg at 25 °C
Thermochemistry
−184.1 kJ·mol−1
Hazards
Safety data sheet Praxair
Flash point −41 °C (-41.8 °F; 232 K)
Related compounds
Related compounds
 Diethyl ether
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Dimethyl ether or DME, also known as methoxymethane, is the organic compound with the formula CH3OCH3 (or C2H6O).

It is the simplest ether and an isomer of ethanol.

Properties

Chemical

Dimethyl ether is flammable and will burn when ignited in an oxygen atmosphere.

CH3-O-CH3 + 3 O2 → 2 CO2 + 3 H2O

Dimethyl ether can be carbonylated to acetic acid. This reaction proceeds under high pressure:

CH3-O-CH3 + 2 CO + H2O → 2 CH3-COOH

Reaction with sulfur trioxide yields dimethyl sulfate:

CH3-O-CH3 + SO3 → (CH3)2SO4

Physical

Dimethyl ether is a colorless gas at standard conditions, with an ethereal smell. It melts at −141 °C and boils at −24 °C. DME is poorly soluble in water (71 g/l at standard conditions), but soluble in most organic solvents, such as acetone, chloroform, ethanol, methanol.

Availability

Dimethyl ether is available in some type of wart remover sprays, usually mixed with propane.

Some car starter fluids also contain dimethyl ether.

MAP-plus blowtorch gas blends may contain DME.

Preparation

Dimethyl ether can be prepared by dehydration of methanol, in the presence of a catalyst, such as conc. sulfuric acid.

2 CH3OH → (CH3)2O + H2O

The resulting gaseous dimethyl ether is then purified, dried and stored either dissolved in a solvent or compressed in a gas tube/lecture bottle.

Projects

Handling

Safety

Dimethyl ether is a flammable gas. It poses relative low toxicity.

Storage

Dimethyl ether can be stored in gas cylinders, which should be kept in cool and dark places, away from light and heat.

Unlike most common ethers, dimethyl ether does not form peroxides upon exposure to air. Therefor, DME solutions do not require antioxidants.

Disposal

DME can be safely burned or released in open air. It poses little threat to the environment.

References

Relevant Sciencemadness threads

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