Dimethyl ether

Dimethyl ether

Names
IUPAC name Methoxymethane
Other names Demeon Dimethyl oxide Dymel A Mether Methyl ether Wood ether
Identifiers
Jmol-3D images	Image
SMILES COC
Properties
Chemical formula	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)
Solubility in water	7.1 g/ 100 ml (at 20 °C)
Solubility	Soluble in acetone, chloroform, ethanol, isopropanol, methanol
Vapor pressure	4450 mmHg at 25 °C
Thermochemistry
Std enthalpy of formation (ΔfHo298)	−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

• Low temperature organic extraction
• Make dimethyl sulfate
• Motor fuel
• Methylating agent for alkenes and toluene

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

• OTC Dimethyl Ether