アセチレン 化学特性,用途語,生産方法
種類
アセチレンは酸素がなくても爆発的に燃焼する危険性がある可燃性ガスです。そのため、通常は圧縮冷却により溶剤 (やDMF) などに加圧溶解させた溶解アセチレンとしてガスボンベに充填されます。
一般的な溶解アセチレンには、不純物に由来する若干の臭いがあります。これは、原材料のカルシウムカーバイドに含まれる不純物 (リン化カルシウムや硫黄など) に由来するやのためです。
その他には、半導体の炭素原料、硬質炭素膜の生成原料などに用いられる高純度製品などがあります。高純度アセチレンガスには、溶解アセチレンガスと、圧縮アセチレンガスがありますが、前述の通り圧縮アセチレンガスは危険性があるため取り扱いの際は注意が必要です。
尚、高圧ガス保安法により、常用の温度で圧力が0.2MPa以上になるもの、または、15℃で0.2MPa以上となるものの場合は、ボンベの色を褐色とするよう定められています。
反応
付加反応
アセチレンの三重結合は付加反応を受けやすい分子です。水素の付加によってエチレン、が順に生成します。また、ハロゲン化水素などの H−X 型の分子も容易に付加反応が可能です。
付加重合
アセチレンは付加重合をすることが可能です。アセチレン2分子の重合によって、モノビニルアセチレンが生成します。モノビニルアセチレンはやクロロプレンの原料として、合成ゴムをつくるときに用いられる物質です。また、アセチレン3分子からはベンゼンが合成されます。重合が進んでポリマー化したポリアセチレンは、導電性物質として利用されています。
解説
アセチレン，常温ではほぼ同体積の水にしか溶解しないが、アルコールやベンゼンなどの有機溶媒には溶け、とくにアセトンにはよく溶ける。アセチレンは高圧で分解しやすいため、珪藻土(けいそうど)にしみ込ませたアセトンに加圧して溶かし、ボンベで運搬する。
性質
アセチレンは燃焼すると発熱量が大きいので、酸素と混ぜて酸素アセチレン炎として、鉄の溶接や切断に用いる。また空中で点火すると、輝きの強い炎で燃えるので、夜店などでアセチレンランプとして用いられる。しかし、アセチレンの酸素または空気との混合ガスはきわめて爆発しやすいので、取扱いには充分の注意が必要である。アセチレンが空気中に2.5～81％含まれていると爆発する。
用途
圧縮酸素と併用して金属の溶接、切断に用い、造船、車両、鉄鋼部門などに主として使用され、また一部スカーフィング（鉄鋼のきずとり及び皮はぎ）にも使用される；酢酸合成、合成樹脂、合成繊維、合成ゴムの原料、レッペ反応による広範囲な有機化合物の合成アセチレンブラック、ガス増熱用燃料、金属アセチリドの製造。
製法
元来は炭化カルシウム（カルシウムカーバイド、生石灰を無煙炭またはコークスと電気炉中で加熱して製造）に水を作用させて製造した。この方法で得られるアセチレンは不純物のため悪臭を有する。現在、工業的には天然ガスやナフサなど石油からの炭化水素を高い温度で熱分解して製造する。その分子は次のような直線状の構造をとる。
説明
Acetylene (100% purity) is odourless, but commercial purity has a distinctive garlic-like
odour and is very soluble in alcohol and almost miscible with ethane. Acetylene is a flammable
gas and kept under pressure in gas cylinders. Under certain conditions, acetylene
can react with copper, silver, and mercury to form acetylides, compounds which can act as
ignition sources. Brasses containing less than 65% copper in the alloy and certain nickel
alloys are suitable for acetylene. Acetylene is not compatible with strong oxidisers such as
chlorine, bromine pentafluoride, oxygen, oxygen difluoride and nitrogen trifluoride, brass
metal, calcium hypochlorite, heavy metals such as copper, silver, mercury, and their salts,
bromine, chlorine, iodine, fluorine, sodium hydride, caesium hydride, ozone, perchloric
acid, and potassium.
化学的特性
Acetylene (100% purity) is odorless but commercial purity has a distinctive garlic-like
odor. It is very soluble in alcohol and almost miscible with ethane. Acetylene is a flammable
gas and kept under pressure in gas cylinders. Under certain conditions, acetylene
can react with copper, silver, and mercury to form acetylides, compounds that can act as
ignition sources. Brasses contain a form acetylides, compounds that can act as ignition
sources. Brasses containing less than 65% copper in the alloy and certain nickel alloys are
suitable for acetylene. Acetylene is not compatible with strong oxidizers such as chlorine,
bromine pentafl uoride, oxygen, oxygen difl uoride, and nitrogen trifl uoride, brass metal,
calcium hypochlorite, heavy metals such as copper, silver, mercury, and their salts, bromine,
chlorine, iodine, fl uorine, sodium hydride, cesium hydride, ozone, perchloric acid,
or potassium.
物理的性質
Acetylene, which is the simplest alkyne hydrocarbon, exists as a colorless, flammable, unstable gas with a distinctive pleasant odor (acetylene prepared from calcium carbide has a garlic smell resulting from traces of phosphine produced in this process). The term acetylenes is used generically in the petroleum industry to denote chemicals based on the carbon-carbon triple bond.
来歴
Acetylene was discovered in 1836 by Edmund Davy (1785-1857) who produced the gas while trying to make potassium metal from potassium carbide (K
2C
2). In 1859, Marcel Morren in France produced acetylene by running an electric arc between carbon electrodes in the presence of hydrogen. Morren called the gas produced carbonized hydrogen. Three years later, Pierre Eugène-Marcelin Berthelot (1827-1907) repeated Morren’s experiment and identified carbonized hydrogen as acetylene.
使用
Illuminant, oxyacetylene welding, cutting, and soldering metals, signalling; pptg metals, particularly Cu; manufacture of acetaldehyde, acetic acid; fuel for motor boats.
調製方法
The traditional method of producing acetylene is from reacting lime, calcium oxide (CaO), with coke to produce calcium carbide (CaC
2). The calcium carbide is then combined with water to produce acetylene:
2CaO
(s) + 5C
(s)→2CaC
2(g) + CO
2(g)CaC
2(s) + 2H
2O
(l)→ C
2H
2(g) + Ca(OH)
2(aq)Several processes for producing acetylene from natural gas and other petroleum products developed in the 1920s. Thermal cracking of methane involves heating methane to approximately 600℃ in an environment deficient in oxygen to prevent combustion of all the methane. Combustion of part of the methane mix increases the temperature to approximately 1,500℃, causing the remaining methane to crack according the reaction: 2CH
4(g) → C2H
2(g) + 3H
2(g). In addition to methane, ethane, propane, ethylene, and other hydrocarbons can be used as feed gases to produce acetylene.
定義
A
gaseous alkyne. Traditionally ethyne has
found use in oxy-acetylene welding
torches, since its combustion with oxygen
produces a flame of very high temperature.
It is also important in the organic chemicals
industry for the production of
chloroethene (vinyl chloride), which is the
starting material for the production of
polyvinyl chloride (PVC), and for the production
of other vinyl compounds. Until
recently, ethyne was manufactured by the
synthesis and subsequent hydrolysis of calcium
dicarbide, a very expensive procedure.
Modern methods increasingly
employ the cracking of alkanes.
反応性
Acetylene reacts (1) with chlorine, to form acetylene tetrachloride C2H2Cl4 or CHCl2·CHCl2 or acetylene dichloride C2H2Cl2 or CHCl:CHCl, (2) with bromine, to form acetylene tetrabromide C2H2Br4 or CHBr2·CHBr2 or acetylene dibromide C2H2Br2 or CHBr:CHBr, (3) with hydrogen chloride (bromide, iodide), to form ethylene monochloride CH2:CHCl (monobromide, monoiodide), and 1,1-dichloroethane, ethylidene chloride CH3·CHCl2 (dibromide, diiodide), (4) with H2O in the presence of a catalyzer, e.g., mercuric sulfate HgO4S, to form acetaldehyde CH3·CHO, (5) with hydrogen, in the presence of a catalyzer, e.g., finely divided nickel heated, to form ethylene C2H4 or ethane C2H6, (6) with metals, such as copper or nickel, when moist, also lead or zinc, when moist and unpurified. Tin is not attacked. Sodium yields, upon heating, the compounds C2HNa and C2Na2. (7) With ammoniocuprous (or silver) salt solution, to form cuprous (or silver) acetylide C2Cu2, dark red precipitate, explosive when dry, and yielding acetylene upon treatment with acid, (8) with mercuric chloride solution, to form trichloromercuric acetaldehyde C(HgCl)3·CHO, precipitate, which yields with HCl acetaldehyde plus mercuric chloride.
一般的な説明
A colorless gas with a faint garlic-like odor. Easily ignited and burns with a sooty flame. Gas is lighter than air. Flame may flash back to the source of a leak very easily. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.
空気と水の反応
Highly flammable. Slightly soluble in water. Reacts with water to form toxic ammonia fumes.
反応プロフィール
Acetylene reacts with alkali metals, forming Hydrogen gas. Acetylene can react explosively with bromine [Von Schwartz 1918. p.142 ]. Acetylene forms a sensitive acetylide when passed into an aqueous solution of mercuric nitrate, [Mellor 4:933. 1946-47]. An Acetylene torch used to drill through a plow frame, which was filled with hydrogen gas, produced an explosion [NIOSH, June 1998]. Acetylene reacts with silver, copper and lead to form sensitive, explosive salts. Since Acetylene is endothermic and effectively a reducing agent, it's reaction with oxidants can be very violent (examples: calcium hypochlorite, nitric acid, nitrogen oxide, ozone, trifluoromethyl hypofluorite, etc.). Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization, due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container [Handling Chemicals Safely 1980]. Acetylene and ammonia can form explosive silver salts in contact with Ag. (Renner, Hermann, Gunther Schlamp. "Silver, Silver Compounds, and Silver Alloys." Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag GmbH & Co. KGaA. 2001.).
危険性
The LEL of acetylene is reached well before asphyxiation can occur, and the danger of explosion is reached before any other health hazard is present. When fighting fires involving acetylene containers, the fire should be extinguished before closing the valve to the container. This is because the acetylene has such a wide flammable range that it can burn inside the container. Acetylene is incompatible with bromine, chlorine, fluorine, copper, silver, mercury, and their compounds. Acetylene has a four-digit UN identification number of 1001. The NFPA 704 designation is health 1, flammability 4, and reactivity 3. Reactivity is reduced to 2 when the acetylene is dissolved in acetone.
健康ハザード
Headache, dizziness and loss of consciousness may occur. Death from ``smothering'' may occur if oxygen content of the air is severely reduced by dilution with Acetylene.
火災危険
Behavior in Fire: May explode in fire
燃焼性と爆発性
Acetylene is a highly flammable gas and forms explosive mixtures with air over an
unusually wide range of concentrations (2 to 80%). Acetylene can polymerize
exothermically, leading to deflagration. With a very high positive free energy of
formation, acetylene is thermodynamically unstable and is sensitive to shock and
pressure. Its stability is enhanced by the presence of small amounts of other
compounds such as methane, and acetylene in cylinders is relatively safe to handle
because it is dissolved in acetone. Acetylene fires can be fought with carbon dioxide,
dry chemical, and halon extinguishers; firefighting is greatly facilitated by shutting
off the gas supply.
使用用途
アセチレンは、金属の溶接や溶断加工における可燃性ガスとして用いられます。火炎温度が高いことによって作業を効率的に行うことが可能で、酸素消費量が少ない故に酸素容器の使用本数を減らすことができるためです。
アセチレンを完全燃焼した場合の火炎温度は3,300℃にも達します。これは他の可燃性ガスと比べても非常に高い温度です。
また、着火温度は305℃と低いため扱いやすく、更に酸素の消費量はプロパンガスの1/4ほどと、溶断ガスの中で最小です。また、反応性が高いことから、、、など、多くの有機化合物をアセチレンから合成することができます。
尚、より純度の高いアセチレンに関しては、下記のような用途があります。
- 半導体の炭素原料
- 硬質炭素膜の生成原料
- カーボンナノチューブ、カーボンナノコイルなどの新素材の合成原料
- 原子吸光分析
工業用途
Acetylene is a colorless, flammable gas with a garlic-like odor. Under compressed conditions, it is highly explosive; however, it can be safely compressed and stored in high-pressure cylinders if the cylinders are lined with absorbent material soaked with acetone. Users are cautioned not to discharge acetylene at pressures exceeding 15 psig (103 kPa), as noted by the red line on acetylene pressure gauges.
With its intense heat and controllability, the oxyacetylene flame can be used for many different welding and cutting operations including hardfacing, brazing, beveling, gouging, and scarfing. The heating capability of acetylene also can be utilized in the bending, straightening, forming, hardening, softening, and strengthening of metals.
職業ばく露
Acetylene can be burned in air or oxygen and is used for brazing, welding, cutting, metallizing, hardening, flame scarfing; and local heating in metallurgy. The flame is also used in the glass industry. Chemically, acetylene is used in the manufacture of vinyl chloride, acrylinitrile, synthetic rubber; vinyl acetate; trichloroethylene, acrylate, butyrolactone, 1,4-butanediol, vinyl alkyl ethers, pyrrolidone, and other substances
製造方法
アセチレンガスの主な製造方法として、以下の2つが挙げられます。
- カーバイド法 : カーバイド（）に水を作用させる方法
- 熱分解法: 炭化水素の熱分解による方法
小規模用途ではカーバイド法によって合成され、熱分解法は大規模な工業的製造方法に限られます。ただし、工業的製造でもカーバイド法を用いることもあります。
貯蔵
Acetylene should be kept stored in a cool, dry place in a tightly sealed container, and
should only be used in a well-ventilated area. Cylinders should be separated from
oxygen and other oxidizers by a minimum of 20 ft or by a barrier of non-combustible material at least 5 ft high, having a fi re resistance rating of at least 30 min. Storage in
excess of 2500 cu ft is prohibited in buildings with other occupancies. Cylinders should
be stored upright with a valve protection cap in place and fi rmly secured to prevent
falling or being knocked over. The cylinders should be protected from physical damage
and avoid dragging, rolling, sliding, or dropping the cylinder. During transport, workers
should use a suitable hand truck for cylinder movement. Care should be taken to
label “No Smoking” or “Open Flames” signs in the storage or use areas. There should
be no sources of ignition. All electrical equipment should be explosion-proof in the storage
and use areas.
輸送方法
UN1001 Acetylene, dissolved, 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
不和合性
The substance may polymerize due to heating. The substance decomposes on heating and increasing pressure, causing a fire and explosion hazard. The substance is a strong reducing agent and reacts violently with oxidants and with fluorine or chlorine under influence of light, causing fire and explosion hazard. Reacts with copper, silver, and mercury or their salts, forming shock-sensitive compounds (acetylides). The content of lines carrying acetylene must not exceed 63% copper. May form explosive mixture with air. Forms shock-sensitive mixture with copper and copper salts; mercury and mercury salts; and silver and silver salts. Reacts with brass, bromine, cesium hydride, chlorine, cobalt, cuprous acetylize; fluorine, iodine, mercuric nitrate; nitric acid, potassium, rubidium hydride; trifluoromethyl hypofluorite; and sodium hydride.
廃棄物の処理
Return refillable compressed gas cylinders to supplier. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration.
アセチレン 上流と下流の製品情報
原材料
準備製品