Dimethyl ether Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
FARBLOSES GAS MIT CHARAKTERISTISCHEM GERUCH.
PHYSIKALISCHE GEFAHREN
Das Gas ist schwerer als Luft und kann sich am Boden ausbreiten. Fernzündung möglich. Das Gas kann sich in tiefer gelegenen Bereichen sammeln und den Luftsauerstoff verdrängen.
CHEMISCHE GEFAHREN
Bildung explosionsfähiger Peroxide unter Einfluss von Lichtund Luft. Beim Verbrennen Bildung reizender Rauche. Reagiert mit Oxidationsmitteln.
ARBEITSPLATZGRENZWERTE
TLV nicht festgelegt (ACGIH 2005).
EG Arbeitsplatz-Richtgrenzwerte: (als TWA) 1000 ppm; 1920 mg/m? (EU 2004).
MAK: 1000 ppm, 1900 mg/m? Spitzenbegrenzung: überschreitungsfaktor II(8); Schwangerschaft: Gruppe D; (DFG 2006).
AUFNAHMEWEGE
Aufnahme in den Körper durch Inhalation.
INHALATIONSGEFAHREN
Eine gesundheitsschädliche Konzentration des Gases in der Luft wird beim Entweichen aus dem Behälter sehr schnell erreicht, besonders in geschlossenen Räumen.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Die Substanz reizt die Augen und die Atemwege. Schnelle Verdampfung kann zu Erfrierungen führen. Möglich sind Auswirkungen auf das Zentralnervensystem. Exposition kann Bewusstseinstrübung verursachen.
LECKAGE
Gefahrenbereich verlassen! Fachmann zu Rate ziehen! Zündquellen entfernen. Persönliche Schutzausrüstung: Atemschutzfilter für organische Gase und Dämpfe..
R-Sätze Betriebsanweisung:
R12:Hochentzündlich.
S-Sätze Betriebsanweisung:
S9:Behälter an einem gut gelüfteten Ort aufbewahren.
S16:Von Zündquellen fernhalten - Nicht rauchen.
S33:Maßnahmen gegen elektrostatische Aufladungen treffen.
Chemische Eigenschaften
Dimethyl ether is a liquefied gas and exists as a liquid at room temperature when contained under its own vapor pressure, or as a gas when exposed to room temperature and pressure.
It is a clear, colorless, virtually odorless liquid. In high concentrations, the gas has a faint ether-like odor.
Verwenden
Dimethyl ether is used as a solvent in aerosol formulations.
Vorbereitung Methode
Dimethyl ether is prepared by the reaction of bituminous or lignite coals with steam in the presence of a finely divided nickel catalyst. This reaction produces formaldehyde, which is then reduced to methanol and dimethyl ether. Dimethyl ether may also be prepared by the dehydration of methanol.
Definition
ChEBI: An ether in which the oxygen atom is connected to two methyl groups.
Allgemeine Beschreibung
Dimethyl ether is a colorless gas with a faint ethereal odor. Dimethyl ether is shipped as a liquefied gas under its vapor pressure. Contact with the liquid can cause frostbite. Dimethyl ether is easily ignited. Its vapors are heavier than air. Any leak can be either liquid or vapor. Dimethyl ether can asphyxiate by the displacement of air. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket.
Air & Water Reaktionen
Highly flammable. Upon standing and exposure to air (oxygen) tendency to form explosive peroxides. When ethers containing peroxides are heated (distilled) they can detonate [Lewis, 3rd ed., 1993, p. 854].
Reaktivität anzeigen
Dimethyl ether is a colorless, highly flammable gas (b. p. -24° C), slightly toxic. Very dangerous fire and explosion hazard when exposed to flame, sparks, heat or strong oxidizers. Violent reaction with aluminum hydride, lithium aluminum hydride. Upon standing and exposure to air (oxygen) tendency to form explosive peroxides. When ethers containing peroxides are heated (distilled) they can detonate [Lewis, 3rd ed., 1993, p. 854].
Health Hazard
Methyl ether produced low inhalation toxicity in rats. Caprino and Togna (1975)reported a 30-minute LC50 value of 396 ppmfor rats. In lethal doses it caused sedation,a gradual depression of motor activity, lossof the sighting reflex, hypopnea, coma, anddeath in mice. Exposure to a 40% mixtureof methyl ether in air resulted in an initialslight increase in heart rate in rabbits, whichwas followed by depression of arterial bloodpressure. Death occurred in 45 minutes. Thearterial and venous partial oxygen pressurewas found to decrease while the venous CO2pressure and the blood pH increased
Reuzel et al. (1981) reported that sub chronic inhalation of methyl ether in ratsdid not cause significant adverse effects.No noticeable effect on organ and bodyweights and no treatment-related changeswere observed. In humans, adverse healtheffect from inhalation of this compoundshould be minimal. However, inhalation ofexcessive quantities can produce intoxicationand loss of consciousness.
Brandgefahr
Behavior in Fire: Containers may explode. Vapors are heavier than air and may travel long distance to a source of ignition and flash back.
Chemische Reaktivität
Reactivity with Water No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.
Pharmazeutische Anwendungen
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 is additionally used as a refrigerant.
Sicherheit(Safety)
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.
LD50 (mouse, inhalation): 386000ppm/30min
LD50 (rat, inhalation): 308g/m3
Carcinogenicity
A lifetime study in rats did not
produce cancer or clear, statistically significant evidence of
chronic toxicity at 25,000 ppm of dimethyl ether.
Environmental Fate
DME released to the atmosphere would be expected to exist
almost entirely in the vapor phase since the vapor pressure is
4450 mmHg at 25 ℃. It is susceptible to photooxidation via
vapor phase reaction with photochemically produced hydroxyl
radicals. An atmospheric half-life of 5.4 days has been calculated.
It will also exhibit very highmobility in soil and, therefore, itmay
leach to groundwater. If DME is released to water, it will not be
expected either to significantly absorb to sediment or suspended
particulate matter, bioconcentrate in aquatic organisms, or
directly photolyze. No data concerning the biodegradation of
DME in environmental media were located but many ethers are
known to be resistant to biodegradation. DME would not be
expected to bioconcentrate in aquatic organisms.
Lager
The liquefied gas is stable when used as a propellant. However, exposure to the air for long periods of time may result in explosive peroxides being slowly formed.
Solutions of liquid dimethyl ether should not be concentrated either by distillation or by evaporation. Dimethyl ether should be stored in tightly closed metal cylinders in a cool, dry place.
läuterung methode
Dry methyl ether by passing over alumina and then BaO, or over CaH2, followed by fractional distillation at low temperatures. Its solubility is 37mL per mL of H2O at 18o, and it is very soluble
Inkompatibilitäten
Dimethyl ether is an aggressive solvent and may affect the gasket materials used in aerosol packaging. Oxidizing agents, acetic acid, organic acids, and anhydrides should not be used with dimethyl ether.
Regulatory Status
Included in the FDA Inactive Ingredients Database (topical aerosols). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.
Dimethyl ether Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
