Propellants dimethyl ether

Other Propellants. Dimethyl ether (DME) [115-10-6] is finding use as an aerosol propeUant. DME is soluble in water, as shown in Table 5. Although this solubiHty reduces DME s vapor pressure in aqueous systems, the total aerosol solvent content may be lowered by using DME as a propeUant. The chief disadvantage is that DME is flammable and must be handled with caution. 

Dimethyl ether is used as a propellant in aerosols. It is also a solvent, a fuel used in welding, and a refrigerant. In high concentrations, it has an anesthetic effect. 

Dimethyl ether has been used as an effective ignition improver for other alternative fuels such as methanol and ethanol and can be used as an aerosol propellant. Like methanol, DME can be synthesized from fossil fuel sources or from biomass. 

The simplest of the ethers would be ether that has the simplest hydrocarbon backbones attached those backbones are the radicals of the simplest hydrocarbon, methane. Therefore, the simplest of the ethers is dimethyl ether, whose formula is CH3OCH3. Dimethyl is used because there are two methyl radicals, and "di-" is the prefix for two. This compound could also be called methyl methyl ether, or just plain methyl ether, but it is better known as dimethyl ether. It is an easily liquified gas that is extremely flammable, has a relatively low ignition temperature of 66°F, and is used as a solvent, a refrigerant, a propellant for sprays, and a polymerization stabilizer. 

The aerosol in its familiar modern form was first described in a patent filed in 1926 by Rotheim for the spraying of insecticides, paints, cosmetics, and fire extinguishants. Subsequent patents described a variety of propellants including chloromethane, hydrocarbons, such as 2-methylpropane, and dimethyl ether. The first successful introduction of aerosols on a large scale occurred in 1942 when a pyrcthroid/scsamc oil formulation pressurized with di-chlorodifluoromethanc (CFC 12) was developed by Goodhue and Sullivan for US military... 

Table 1 Properties of fluorocarbon propellants and dimethyl ether s...

A major current issue is the suppression of the use of CFCs due to ozone depletion. Other liquid propellants (134a, 227, or dimethyl ether) are not used as easily as the CFCs and formulation is very difficult. So, many of these dosage forms disappeared or were substituted by saltcellar systems. The use of very volatile solvents, such as volatile silicone, can be proposed if their boiling point is close to room tempera-ture, the use of butane is not recommended due to the explosion risks. 

Dimethyl ether may be used as an aerosol propellant for topical aerosol formulations in combination with hydrocarbons and other propellants. Generally, it cannot be used alone as a propellant owing to its high vapor pressure. Dimethyl ether is a good solvent and has the unique property of high water solubility, compared to other propellants. It has frequently been used with aqueous aerosols. A coarse, wet, spray is formed when dimethyl ether is used as a propellant. 

Dimethyl ether is also used as a propellant in cosmetics such as hair sprays, and in other aerosol products such as air fresheners and fly sprays. 

Dimethyl ether may be used as a propellant and solvent in topical pharmaceutical aerosols, and is generally regarded as an essentially nontoxic and nonirritant material when used in such applications. However, inhalation of high concentrations of dimethyl ether vapor is harmful. Additionally, skin contact with dimethyl ether liquid may result in freezing of the skin and severe frostbite. 

When used in topical formulations, dimethyl ether may exert a chilling effect on the skin, although if it is used as directed the propellant quickly vaporizes and is nonirritating. 

Dimethyl ether (CH3OCH3) is a good substitute for environmentally harmful propellants in aerosol spray cans. It is produced by the dehydration of methanol ... 

Dimethyl ether is used as a refrigerant, as a propellant in aerosol products, as a starter for gasoline engines in cold weather, as a rocket propellant, and as a specialty solvent in chemical synthesis. 

Bohnenn LJM (1979) Dimethyl ether Alternative aerosol propellant. Drug and Cosmetic Industry 125 58-74. 

Dimethyl ether has been increasingly used as a propellant in aerosol formulations to replace chloro-fluorocarbons, which are found to destroy the ozone layer of the atmosphere. Dimethyl ether is nontoxic and easily degrades in the troposphere. Although about 90% of the major current U.S. aerosol industry uses hydrocarbon-based propellants (mostly isobutane and propane), DME could become a more widely used propellant in the coming years. Several aerosol-based... 

Dimethyl ether (DME) has been used as a fuel and propellant. It is miscible with most organic solvents and is currently under study as a fuel additive for diesel engines due to its high volatility and high cetane number. DME, like other synthetically derived fuels, can be produced from syngas, is essentially sulfur free, contains nearly zero aromatic compounds, and is considered an excellent substitute for conventional diesel and liquefied petroleum gas (LPG). DME has several physical properties similar to those of LPG. 

Methanol can be converted to dimethyl ether (DME) by passing the vapors over a dehydration catalyst such as silica/alumina or y-alumina at temperatures of 250°C or higher. Dimethyl ether can be used as an aerosol propellant and also as a precursor to a variety of hydrocarbons and organic chemicals it also can be used as a refrigerant and a cold starting fluid for automobile engines. The reaction is [30] ... 

Hair sprays are used by many persons to hold their hair in place. A typical spray consists of a polymer in ethanol and a little water with dimethyl ether and /j-butane as propellants.353 These organic compounds contribute to ground level ozone. They also are a fire hazard. Efforts are under-... 

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