What Is Dimethyl Ether?
Dimethyl ether, also known as DME or methyl ether, has the molecular formula C2H6O and CAS number 115-10-6. It is the simplest aliphatic ether and a structural isomer of ethanol, which means both compounds share the same atoms arranged in different structures. Under ambient conditions DME is a colourless gas with a faint ethereal odour and it is extremely flammable. Because it liquefies under moderate pressure, it is stored and shipped in pressurised cylinders or in refrigerated tanks.
DME contains no sulphur, no nitrogen and no carbon-carbon bond, so it burns with a clean flame and produces very little soot. This combination of physical and combustion properties explains why the molecule has become important in three separate markets: energy, aerosols and chemical synthesis.
Key Properties That Drive Its Use
| Property | Typical value |
|---|---|
| Molecular formula | C2H6O |
| CAS number | 115-10-6 |
| Boiling point | about -24.8 °C |
| Physical state at 20 °C | Gas, liquefied under moderate pressure |
| Cetane number | roughly 55 - 60 |
| Sulphur content | essentially sulphur free |
| Solubility | Soluble in water and in many organic solvents |
| Corrosivity | Non-corrosive to common metals |
Its vapour pressure is well suited to aerosol dispensing, its high cetane number makes it attractive for compression-ignition engines, and its solvent power allows it to carry a wide range of active ingredients.
Use as an Aerosol Propellant and Alternative Fuel
Because DME is a liquefied gas with excellent solvency, it is widely used as a propellant in spray paints, deodorants, air fresheners, insecticides and technical aerosols. It evaporates rapidly, leaves little residue and is compatible with many active ingredients. It has replaced chlorofluorocarbons and a share of hydrocarbon propellants in consumer aerosol formulations, helping formulators reduce volatile organic compound content while maintaining spray quality and stable pressure.
In the energy sector, DME can be produced from methanol, natural gas, coal or biomass. It substitutes for liquefied petroleum gas in heating and cooking, and as a diesel alternative its high cetane number supports clean combustion with low particulate and nitrogen oxide emissions. Blends of DME with LPG have been used in existing appliances, and dedicated DME-fuelled vehicles and refuelling infrastructure have been demonstrated in several Asian markets.
Chemical Feedstock Applications
In the chemical industry DME is an intermediate for dimethyl sulfate, methyl acetate, acetic acid and other compounds used in pharmaceuticals, dyes, agrochemicals, paints and adhesives. Catalyst developments have also opened routes that convert DME into olefins, providing a pathway from coal or natural gas to plastics. Its position as a platform molecule continues to strengthen as methanol-to-DME and DME-to-olefin technologies mature.
In agriculture, DME serves as a solvent and dispersion aid in pesticide formulations, helping active ingredients spread evenly and penetrate the target surface. Its low boiling point means the carrier leaves the treated surface quickly, leaving the active ingredient in place.
Safety, Handling and Storage
DME is flammable and forms explosive mixtures with air, so storage areas must be well ventilated and free of ignition sources. Electrical equipment should be suitable for a flammable gas atmosphere. Pressurised containers must be stored upright, protected from heat and direct sunlight, and inspected regularly for valve integrity and corrosion.
Personnel should follow the safety data sheet, wear appropriate personal protective equipment and work in systems designed for flammable gas service. Because DME is a liquefied gas, contact with the liquid or with rapidly expanding gas can cause cold burns, so gloves and face protection are required when breaking connections.
Frequently Asked Questions
Q: What is the CAS number of dimethyl ether?
The CAS registry number of DME is 115-10-6 and its molecular formula is C2H6O.
Q: Is dimethyl ether a liquid or a gas?
DME is a gas at room temperature and atmospheric pressure, but it liquefies easily under moderate pressure.
Q: Is DME the same as ethanol?
No. DME is a structural isomer of ethanol with the same molecular formula C2H6O but completely different physical and chemical properties.
Q: Can DME be used as a fuel?
Yes. It is used as a clean-burning fuel for heating and cooking and as a diesel substitute because of its high cetane number.
Q: What is DME used for in aerosols?
It acts as both propellant and solvent in spray paints, deodorants, air fresheners and insecticide sprays.
Q: Is dimethyl ether flammable?
Yes. DME is extremely flammable and must be handled away from ignition sources with proper ventilation and bonding.