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解説
エテン，脂肪族不飽和炭化水素(アルケン)のもっとも簡単なもの．エチレンとよばれたこともあったが，現在では二価基-CH2-CH2-をエチレンと命名し，エテンと区別することになっている．ガソリン製造のための重質油熱分解における副生ガス，また石炭乾留ガス中にも含まれる．
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性質
エテン，構造は構成原子はすべて同一平面上にあり，C=C0.134 nm，C-H0.109 nm．∠H-C-H118°，∠H-C-C121°．オレフィン臭をもつ引火性の無色の気体．融点－169.15 ℃，沸点－103.71 ℃．爆発範囲2.75～28.60体積％．水，エタノール，エーテルに微溶．二重結合への各種付加反応，重合反応，酸化反応を受けやすい．
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用途
主にナフサ分解で生産され、ポリエチレン等の合成樹脂原料として使用される他、各種化学製品の原料として使用されます。
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製法
工業的には，エタンより炭素数の多い石油系炭化水素の熱分解で生成する，分解ガスの低温精留により分離製造される．
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説明
Ethylene is a colorless, odorless gas that is the simplest alkene hydrocarbon. It is a natural plant
hormone and is produced synthetically from natural gas and petroleum. The double bond in
ethylene makes this compound highly reactive, and the volume of ethylene used in the chemical
industry is greater than any other organic compound.
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化学的特性
Ethylene, an alkene is a colorless gas (at room
temperature). Sweet odor. Minimum detectable odor 5
260 ppm.
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使用
Oxyethylene welding and cutting metals; manufacture of alcohol, mustard gas, and many other organics. manufacture of ethylene oxide (for plastics), "Polythene", polystyrene and other plastics. Plant growth regulator; used commercially to accelerate the ripening of various fruits.
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調製方法
Ethylene is primarily obtained from the ethane and propane components of natural gas andfrom the naphtha, kerosene, and gas oil components of crude oil. It can also be synthesizedthrough the dehydration of ethanol (C2H5OH). The production of ethylene from hydrocarbonfeedstocks involves mixing with steam and then subjecting the hydrocarbons to thermalor catalytic cracking. Cracking is a process in which organic molecules are broken down intosmaller molecules. Thermal cracking involves the use of heat and pressure. Catalytic crackinguses various catalysts to reduce the amount of heat and pressure required in the process.Th ermal cracking of hydrocarbons to ethylene occurs between approximately 650°C and800°C (1200°F and 1500°F). After hydrocarbons are cracked, a mixture containing ethyleneand other gases such as methane, ethane, and propane is obtained. Ethylene is separated fromthese through physical processes such as fractional distillation, refrigeration, absorption, oradsorption.
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定義
ethylene: A colourlessflammable gaseous hydrocarbon,C2H4; m.p. –169°C; b.p. –103.7°C. It isthe first member of the alkene seriesof hydrocarbons. It is made bycracking hydrocarbons from petroleumand is now a major raw materialfor making other organicchemicals (e.g. ethanal, ethanol,ethane-1,2-diol). It can be polymerizedto polyethene. It occurs naturallyin plants, in which it acts as agrowth substance promoting theripening of fruits.
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反応性
Ethylene reacts: (1) with the halogens to form substitution halides; (2) with hypochlorous and hypobromous acid to form ethylene chlorohydrin or ethylene bromohydrin, respectively; (3) with hydrogen iodide or bromide (not chloride) to form ethyl iodide or ethyl bromide; (4) with hydrogen, in the presence of a catalyst, e.g., finely divided nickel at 150 °C, to form ethane; (5) with concentrated sulfuric acid at 160 °C to form ethyl hydrogen sulfate; and (6) with potassium permanganate to form ethylene glycol, although glycol is preferably made from ethylene dichloride or chlorohydrin.
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一般的な説明
A colorless gas with a sweet odor and taste. ETHYLENE is lighter than air. ETHYLENE is easily ignited and a flame can easily flash back to the source of the leak. Under prolonged exposure to fire or heat the containers may rupture violently and rocket. Can cause explosion.
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空気と水の反応
Highly flammable.
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反応プロフィール
Peroxidizable monomer may initiate exothermic polymerization of the bulk material [Bretherick 1979. p. 160]. ETHYLENE in the presence of aluminum chloride may undergo a violent reaction [J. Inst. Pet. 33:254. 1947]. Ozone and ETHYLENE react explosively [Berichte 38:3837]. ETHYLENE can polymerize at low pressure if catalyzed by titanium halides. (Sundaram, K. M, M. M. Shreehan, E. F. Olszewski. thylene. Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. 2001.)
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危険性
Highly flammable, dangerous fire and
explosion risk; explosive limits in air 3–36% by
volume. Simple asphyxiant; questionable carcinogen.
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健康ハザード
Exposure to ethylene atmosphere can causeasphyxiation. At high concentrations it is anarcotic and can cause unconsciousness.
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火災危険
Flammable gas; burns with a luminous flame;
autoignition temperature 490°C (914°F)
(NFPA 1997), 543°C (1009°F) (Merck
1996); fire-extinguishing measure: shut off
the flow of gas; use a water spray to keep
fire-exposed containers cool.
Ethylene forms explosive mixtures in
air; the LEL and UEL values are 2.7%
and 36% by volume of air, respectively.
Its reaction with fluorine is explosively
violent (△H=- 112 kcal/mol), and violent
with chlorine (△H=- 36 kcal/mol). In the
presence of sunlight or UV light, an ethylene–
chlorine mixture will explode spontaneously.
The reaction is explosive at room
temperature over the oxides of mercury or
silver (Mellor 1946, Suppl. 1956). Ethylene
reacts vigorously with oxidizing substances.
It reacts with ozone to form ethylene
ozonide, H2C(O3)CH2, which is unstable
and explodes on mechanical shock. Acidcatalyzed
addition of hydrogen peroxide
may produce ethyl hydroperoxide, which is
unstable and explodes on heat or shock:.
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使用用途
エチレンには、エチレン自体が用いられる用途と、エチレンが有機化合物の合成材料として用いられる用途があります。
エチレン (ガス) は、植物ホルモンとして様々な生理活性作用が知られています。具体的には、バナナやキウイフルーツの追熟や、ばれいしょの萌芽抑制を目的とした用途です。
果樹やトマトなどの植物生育調整剤として用いられるエテホン液剤の主成分は、2-クロロエチルホスホン酸の水溶液ですが、植物に散布後、分解してエチレンを発生させることで、植物生育調整剤としての効果を発現します。
エチレンは単純な構造の炭化水素であること、反応性に富む二重結合を有することから、様々な低分子化合物、高分子化合物の材料として用いられています。
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物性
融点が-169℃、沸点が-104℃なので、常温では気体の状態で存在しています。エチレンの比重は0.975と空気 (比重1) に近く、色も無色であることから空気と区別がつきにくいです。
しかし、引火性や発火性を有し、火災によって刺激性、または毒性のガスを発生する可能性があるため、取り扱いには注意が必要です。
また、エチレンは、自然界にも存在しており、野菜や果物から発生していることが分かっています。これは植物ホルモンの1種であり、野菜や果物を成熟させ、その後腐敗させるというエイジングの役割を持っています。
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材料の用途
Installations must be designed to withstand the
pressures involved and must comply with all
applicable regulations. Because it is noncorrosive,
any common commercially available metals
may be used with ethylene.
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安全性プロファイル
Suspected carcinogen.
A simple asphyxiant. High concentrations
cause anesthesia. A common air
contaminant. It is phytotoxic. A very
dangerous fire hazard when exposed to heat
or flame. Moderate explosion hazard when
exposed to flame. A flammable gas. To figh fire, stop flow of gas, use Co2, dry chemical,
or fine water spray. Mixtures with aluminum
chloride explode in the presence of nickel
catalysts, methyl chloride, or nitromethane.
Explosive reaction with
bromotrichloromethane (at 120℃/51 bar),
carbon tetrachloride (25-100°C/30 bar).
Explosive reaction with chlorine catalyzed
by sunlight or UV light or in the presence of
mercury(I) oxide, mercury(Ⅱ) oxide, or
silver oxide. Mixtures with
chlorotrifluoroethylene polymerize
explosively when exposed to 50 kV gamma
rays at 308 krad/hr. Has been involved in
industrial accidents. Violent polymerization
is catalyzed by copper above 4OO0C/54 bar.
Incompatible with AlCl3, (CC4 + benzoyl
peroxide), (bromotrichloromethane +
NCh), 03, CCl4, Cl2, NOx,
tetrafluoroethylene trifluorohypofluorite.
When heated to decomposition it emits
acrid smoke and irritating fumes
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職業ばく露
Ethylene is used in production of fabricated plastics, antifreeze; making fibers; to manufacture ethylene oxide, polyethylene for plastics, alcohol, mustard gas and
other organics. It is used to accelerate ripening of fruit; as an
anesthetic; and for oxyethylene welding and cutting of metals
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概要
エチレンとは、2つの炭素が二重結合で結ばれた炭化水素で、もっとも単純な構造を有するアルケンです。
常温の状態では気体として安定している物質ですが、やプロパン、ブタンなどの物質を熱分解したり、石油ナフサをクラッキングしたりすることで工業的に生成することもできます。
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発がん性
A case-control study of brain
cancer among Texas petrochemical workers reported
increased risks associated with exposure to multiple chemicals,
including ethene. The findings were not
statistically significant. The risks for ethene have not been
shown to increase with increasing duration of employment. The observed increases could not be attributed to specific
chemical exposures.
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製造方法
エチレンは工業的に製造されています。最も主流の方法は、様々な炭化水素を含む石油ナフサと水蒸気を800℃以上の高温で反応させ、生成する水素やエチレン、プロピレン、芳香族化合物などからエチレンを分離するものです。その他、シェールガスに含まれるエタンを熱分解する手法もあります。
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環境運命予測
Emitted ethene is distributed primarily into the atmosphere
and reacts with photochemically reactive hydroxyl radicals,
ozone, and nitrate radicals, with half-lives ranging from 1.9,
6.5, and 190 days, respectively. Biodegradation in water occurs
with half-lives in the range of 1–28 days, or under anaerobic
conditions, 3–112 days. Bioaccumulation in aquatic organisms
is not expected to occur, based on ethene’s high vapor pressure
and log octanol/water partition coefficient.
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貯蔵
Ethylene is stored in a cool, well-ventilatedarea isolated from oxygen, chlorine, andflammable and oxidizing substances. It isprotected against lightning, statical electricity,heat, and physical damage. It is shippedin steel pressure cylinders and tank barges.
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輸送方法
UN1962 Ethylene, Hazard Class: 2.1; Labels:
2.1-Flammable gas; UN1038 Ethylene, refrigerated liquid
(cryogenic liquid), Hazard Class: 2.1; Labels: 2.1-
Flammable gas. Cylinders must be transported in a secure
upright position, in a well-ventilated truck. Protect cylinder
and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal
law (49CFR) to transport and refill them. It is a violation
of transportation regulations to refill compressed gas cylinders without the express written permission of the owner.
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純化方法
Purify ethylene by passage through a series of towers containing molecular sieves or anhydrous CaSO4 or a cuprous ammonia solution, then conc H2SO4, followed by KOH pellets. Alternatively, it has been condensed in liquid nitrogen, with melting, freezing and pumping to remove air before passage through an activated charcoal trap, followed by a further condensation in liquid air. A sputtered sodium trap was used to remove oxygen. [Beilstein 1 IV 677.]
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不和合性
A highly flammable gas at room temperature. Contact with oxidizers may cause explosive polymerization and fire. May be spontaneously explosive in
sunlight or ultraviolet light when mixed with chlorine.
Reacts violently with mixtures of carbon tetrachloride and
benzoyl peroxide; bromotrichloromethane; aluminum chloride and ozone. Incompatible with acids, halogens, nitrogen
oxides; hydrogen bromide; aluminum chloride; chlorine
dioxide; nitrogen dioxide. May accumulate static electrical
charges, and may cause ignition of its vapors.
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廃棄物の処理
Return refillable compressed
gas cylinders to supplier
