-
定義
DMEは、ジメチルエーテルの表示名称である。本品は、次の化学式で表されるエーテルである。
-
解説
C2H6O(46.07)．CH3OCH3．メチルエーテルともいう．脂肪族エーテル類のもっとも簡単なもの．メチルアルコールを硫酸と熱して得られるエーテル。無色の芳香のある気体で、引火しやすい。液化石油ガス（LPG）によく似た性質をもち、代替燃料としても利用される。DME。快香を有する無色の気体．融点－141.50 ℃，沸点－24.8 ℃．エタノールに易溶，水，硫酸に可溶．低温でハロゲン，ハロゲン化水素などと一連の付加物を形成する．おもに溶剤，あるいは冷却剤として用いられるが，最近，GTLの製品の一つとして燃料に，また，排気ガス中のPM(パーティキュレート；粒子状物質)が少ないディーゼル燃料としての用途も考えられている．森北出版「化学辞典（第2版）
-
用途
冷媒、抽出溶媒
-
製造法
製法は，実験室的には，メタノールに硫酸を加えて加熱する．工業的には，メタノールを酸性触媒で脱水する方法と，合成ガスから一段で合成する方法とが開発されている．構造は二つのメチル基が酸素で結ばれたもので，∠C-O-C111°である．
-
化粧品の成分用途
減粘剤、噴射剤、溶剤
-
化学的特性
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.
-
使用
Dimethyl ether is used as a solvent in aerosol formulations.
-
調製方法
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.
-
定義
ChEBI: An ether in which the oxygen atom is connected to two methyl groups.
-
一般的な説明
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.
-
空気と水の反応
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].
-
反応プロフィール
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].
-
健康ハザード
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.
-
火災危険
Behavior in Fire: Containers may explode. Vapors are heavier than air and may travel long distance to a source of ignition and flash back.
-
特徴と使用用途
①LPガスの代価燃料としての応用
本化合物には、常温で気体であり、圧縮する事で容易に液化し、さらには可燃性を有するという特徴があります。現在はスプレー用の噴射剤としての利用が主ですが、LPガスと同じような貯蔵・取り扱いが可能なため、LPガスの代替燃料として、家庭用燃料、発電用燃料、ディーゼル燃料など、幅広い用途への応用が期待されています。
②環境に優しいクリーンエネルギーとしての利用
ここで、ジメチルエーテルは、分子内にC-C結合を持たないため煤は発生しません。さらには硫黄原子を持たないためSOxを発生させる危険性もありません。そのため、ジメチルエーテルは化石燃料に変わる次世代のクリーンエネルギーとしての応用が期待されています。
-
毒性??危険性
人体に対する毒性としては麻酔作用があり、吸引すると軽度の麻痺状態となる事が知られています。物性としての危険性に関しては、可燃性と爆発性を有するため、その保管と使用には充分な注意が必要です。ただし、ジメチルエーテルは、これとよく比較されるLPガスに比べて引火性が低く、爆発限界も2倍程度高いです。そのため、比較的安全な燃料であるといえます。
-
合成??製造
実験室レベルでは、を濃硫酸と加熱する事で得られます。工業生産レベルにおいては、リン酸アルミニウム触媒存在下でメタノールを脱水する事で調製します。これらの製造法は間接法と呼ばれており、現在主流の製造方法になります。他にも、天然ガス、石炭、バイオマスなどから、分子状水素を調製し、そこから直接DMEを合成する方法もあり、これを直接法と呼びます。
-
物理化学的諸性質
①名称
和名：ジメチルエーテル
英名：dimethyl ether
英名略称:DME
IUPAC名：methoxymethane
②溶媒溶解性
、に可溶。
-
化学反応性
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.
-
応用例（製薬）
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.
-
安全性
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
-
発がん性
A lifetime study in rats did not
produce cancer or clear, statistically significant evidence of
chronic toxicity at 25,000 ppm of dimethyl ether.
-
環境運命予測
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.
-
貯蔵
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.
-
純化方法
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
-
不和合性
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.
-
規制状況(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.
