出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/03/16 20:35:53」(JST)
| 四塩化炭素 | |
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| 一般情報 | |
| IUPAC名 | 四塩化炭素、テトラクロロメタン |
| 分子式 | CCl4 |
| 分子量 | 153.82 g/mol |
| 形状 | 無色液体 |
| CAS登録番号 | [56-23-5] |
| SMILES | ClC(Cl)(Cl)Cl |
| 性質 | |
| 密度と相 | 1.5842 g/cm3, 液体 |
| 水への溶解度 | 0.08 g/100 mL (20 ℃) |
| 融点 | −22.9 °C |
| 沸点 | 76.8 °C |
四塩化炭素（しえんかたんそ、英: carbon tetrachloride）あるいはテトラクロロメタン（英: tetrachloromethane）は、化学式 CCl4 で表される化学物質。
常温・常圧では無色透明の液体で、わずかに甘い特異臭を持つ。水には溶けにくい。エタノールやベンゼンなどと任意の割合で混合する。以前は溶剤のほか、消火剤や冷却材として広く利用され、俗に四塩炭（しえんたん）とも呼ばれていたが、その毒性の為に既に使用が禁止された。現在では試薬としてのみ流通している。
「四塩化炭素」、「テトラクロロメタン」のどちらも IUPAC名として使用できるが、これは無機化合物と見るか有機化合物と見るかで区別されているためである。
四塩化炭素の多くは二硫化炭素の塩素化により生産されている。反応温度は 105 ℃ から 130 ℃ である。
またジクロロメタンやクロロホルム生産時の副生成物としても得られてくる。
四塩化炭素分子は1個の炭素に4個の塩素が結合した四面体構造を取っている。このため分子全体としては双極子モーメントを持たず、無極性分子である。
溶媒としては、他の無極性物質を溶解するのに適している。揮発性があるため、他の塩素系溶媒と同じく特有の臭気を発する。炭素−水素結合がないため、四塩化炭素がフリーラジカル反応を起こすことは難しい。このためハロゲンガスや NBS 等を用いたハロゲン化反応に利用することができる。
不燃性である。
高温下で金属と接触させることによりホスゲンが生成する。水分が共存すると徐々に分解し、鉄などの金属を腐食するので、水分の混入を避けて、風通しのよい冷所に保管する。
20世紀前半には、ドライクリーニングの溶剤、冷却材、消火器の薬剤などに幅広く利用されていた。また機械器具の脱脂に使われ、オーディオなどでは接点復活剤やテープレコーダーヘッドの清掃溶剤として用いられてきた。しかし健康への悪影響が明らかになってくると代替物質への転換が進み、1940年をピークに使用量は減少していった。その後も貯蔵穀物に対する農薬として利用されていたが、アメリカ合衆国では1970年に消費財への使用が禁止された。
モントリオール議定書が成立するまでは、フロンの原料としても大量に使用されていた。その後フロンや四塩化炭素自体がオゾン層破壊物質と考えられるようになったため、四塩化炭素の使用量も減少していった。日本やアメリカ合衆国といった先進国では1996年までに生産が全廃されたが、発展途上国では2006年現在でも生産が認められている。
ニュートリノの検出にも用いられる。またアッペル反応では塩素源として利用される。
IRスペクトル(赤外分光測定)では > 1600 cm−1の領域で大きなシグナルを持たないため、時として赤外分光測定において便利な溶媒として用いられることがある。また水素原子を持たないため、1H−NMRの溶媒としても長年用いられてきた。しかし毒性が大きく溶解力が小さいという欠点を持っているため[1]、分光器によりロックをかけることができる重溶媒を用いることが主流となった。
麻酔性があり、高濃度の蒸気や溶液に晒されることにより中枢神経に悪影響を与え、長期に曝露するなどした場合は昏睡、そして死亡する可能性がある。また慢性的な暴露により肝臓や腎臓に悪影響を与え、また、悪性腫瘍の発生を誘発する可能性もあると見られている。作用機序としては、四塩化炭素がシトクロムP450(cytochrome P450 2E1) により代謝され、反応性の高いトリクロロメチルラジカルを生じるというものが考えられている。国際がん研究機関の発がん性評価では、グループ2Bの「発がん性の可能性がある物質」に分類されている。取り扱う際にはSDSなどにより情報を収集し、充分に注意を払う必要がある。
日本では労働安全衛生法により第二類物質の特別有機溶剤等に、PRTR法により第1種指定化学物質に、毒物及び劇物取締法により原体と製剤が劇物に指定されている。
化学物質の審査及び製造等の規制に関する法律 (化審法) 昭和四十八年 法律百十七号 第二条 3により第二種特定化学物質として指定されている[2]
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四塩化炭素研究データ
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| Names | |||
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| IUPAC name
Carbon tetrachloride, Tetrachloromethane
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| Other names
Benziform, Benzinoform, Carbon chloride, Carbon tet, Freon-10, Refrigerant-10, Halon-104, Methane tetrachloride, Methyl tetrachloride, Perchloromethane, Tetraform, Tetrasol
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| Identifiers | |||
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CAS Number
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56-23-5 Y | ||
| 3D model (Jmol) | Interactive image | ||
| ChEBI | CHEBI:27385 Y | ||
| ChEMBL | ChEMBL44814 Y | ||
| ChemSpider | 5730 Y | ||
| ECHA InfoCard | 100.000.239 | ||
| EC Number | 200-262-8 | ||
| KEGG | C07561 Y | ||
| PubChem | 5943 | ||
| RTECS number | FG4900000 | ||
| UNII | CL2T97X0V0 Y | ||
| UN number | 1846 | ||
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InChI
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SMILES
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| Properties | |||
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Chemical formula
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CCl4 | ||
| Molar mass | 153.81 g·mol−1 | ||
| Appearance | colourless liquid | ||
| Odor | ether-like odor | ||
| Density | 1.5867 g cm−3 (liquid) 1.831 g cm−3 at −186 °C (solid) |
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| Melting point | −22.92 °C (−9.26 °F; 250.23 K) | ||
| Boiling point | 76.72 °C (170.10 °F; 349.87 K) | ||
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Solubility in water
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0.097 g/100 mL (0 °C) 0.081 g/100 mL (25 °C) |
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| Solubility | soluble in alcohol, ether, chloroform, benzene, naphtha, CS2, formic acid | ||
| log P | 2.64 | ||
| Vapor pressure | 11.94 kPa at 20 °C | ||
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Henry's law
constant (kH) |
2.76x10−2 atm-cu m/mol | ||
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Magnetic susceptibility (χ)
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-66.60·10−6 cm3/mol | ||
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Refractive index (nD)
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1.4607 | ||
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Dipole moment
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0 D | ||
| Structure | |||
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Crystal structure
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Monoclinic | ||
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Coordination geometry
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Tetragonal | ||
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Molecular shape
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Tetrahedral | ||
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Dipole moment
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0 D | ||
| Thermochemistry | |||
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Specific
heat capacity (C) |
132.6 J/mol K | ||
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Std molar
entropy (S |
214.42 J/mol K | ||
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Std enthalpy of
formation (ΔfH |
-139.3 kJ/mol | ||
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Gibbs free energy (ΔfG˚)
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-686 kJ/mol | ||
| Hazards | |||
| Safety data sheet | See: data page ICSC 0024 |
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EU classification (DSD)
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T N | ||
| R-phrases | R23/24/25, R40, R48/23, R59, R52/53 | ||
| S-phrases | (S1/2), S23, S36/37, S45, S59, S61 | ||
| NFPA 704 |
0
3
0
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| Flash point | Non-flammable | ||
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Autoignition
temperature |
982 °C (1,800 °F; 1,255 K) | ||
| Lethal dose or concentration (LD, LC): | |||
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LD50 (median dose)
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2350 mg/kg | ||
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LC50 (median concentration)
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5400 ppm (mammal) 8000 ppm (rat, 4 hr) |
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LCLo (lowest published)
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1000 ppm (human) 20,000 ppm (guinea pig, 2 hr) |
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| US health exposure limits (NIOSH): | |||
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PEL (Permissible)
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TWA 10 ppm C 25 ppm 200 ppm (5-minute maximum peak in any 4 hours)[1] | ||
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REL (Recommended)
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Ca ST 2 ppm (12.6 mg/m3) [60-minute][1] | ||
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IDLH (Immediate danger)
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200 ppm[1] | ||
| Related compounds | |||
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Other cations
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Silicon tetrachloride Germanium tetrachloride |
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Related chloromethanes
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Chloromethane Dichloromethane |
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Related compounds
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Tetrafluoromethane Tetrabromomethane |
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| Supplementary data page | |||
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Structure and
properties |
Refractive index (n), Dielectric constant (εr), etc. |
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Thermodynamic
data |
Phase behaviour solid–liquid–gas |
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Spectral data
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UV, IR, NMR, MS | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Y verify (what is YN ?) | |||
| Infobox references | |||
Carbon tetrachloride, also known by many other names (the most notable being tetrachloromethane, also recognized by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting and Refrigerant-10 in HVACR, is an organic compound with the chemical formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants and as a cleaning agent. It is a colourless liquid with a "sweet" smell that can be detected at low levels. It has practically no flammability at lower temperatures.
Carbon tetrachloride was originally synthesized by the French chemist Henri Victor Regnault in 1839 by the reaction of chloroform with chlorine,[3] but now it is mainly produced from methane:
The production often utilizes by-products of other chlorination reactions, such as from the syntheses of dichloromethane and chloroform. Higher chlorocarbons are also subjected to "chlorinolysis":
Prior to the 1950s, carbon tetrachloride was manufactured by the chlorination of carbon disulfide at 105 to 130 °C:[4]
The production of carbon tetrachloride has steeply declined since the 1980s due to environmental concerns and the decreased demand for CFCs, which were derived from carbon tetrachloride. In 1992, production in the U.S./Europe/Japan was estimated at 720,000 tonnes.[4]
In the carbon tetrachloride molecule, four chlorine atoms are positioned symmetrically as corners in a tetrahedral configuration joined to a central carbon atom by single covalent bonds. Because of this symmetrical geometry, CCl4 is non-polar. Methane gas has the same structure, making carbon tetrachloride a halomethane. As a solvent, it is well suited to dissolving other non-polar compounds, fats, and oils. It can also dissolve iodine. It is somewhat volatile, giving off vapors with a smell characteristic of other chlorinated solvents, somewhat similar to the tetrachloroethylene smell reminiscent of dry cleaners' shops.
Solid tetrachloromethane has two polymorphs: crystalline II below −47.5 °C (225.6 K) and crystalline I above −47.5 °C.[5] At −47.3 °C it has monoclinic crystal structure with space group C2/c and lattice constants a = 20.3, b = 11.6, c = 19.9 (.10−1 nm), β = 111°.[6]
With a specific gravity greater than 1, carbon tetrachloride will be present as a dense nonaqueous phase liquid if sufficient quantities are spilled in the environment.
In organic chemistry, carbon tetrachloride serves as a source of chlorine in the Appel reaction.
Prior to the Montreal Protocol, large quantities of carbon tetrachloride were used to produce the chlorofluorocarbon refrigerants R-11 (trichlorofluoromethane) and R-12 (dichlorodifluoromethane). However, these refrigerants play a role in ozone depletion and have been phased out. Carbon tetrachloride is still used to manufacture less destructive refrigerants. Carbon tetrachloride has also been used in the detection of neutrinos.
It once was a popular solvent in organic chemistry, but, because of its adverse health effects, it is rarely used today.[7] It is sometimes useful as a solvent for infrared spectroscopy, because there are no significant absorption bands > 1600 cm−1. Because carbon tetrachloride does not have any hydrogen atoms, it was historically used in proton NMR spectroscopy. In addition to being toxic, its dissolving power is low.[8] Its use has been largely superseded by deuterated solvents. Use of carbon tetrachloride in determination of oil has been replaced by various other solvents, such as tetrachloroethylene.[7] Because it has no C-H bonds, carbon tetrachloride does not easily undergo free-radical reactions. It is a useful solvent for halogenations either by the elemental halogen or by a halogenation reagent such as N-bromosuccinimide (these conditions are known as Wohl-Ziegler Bromination).
In 1910, the Pyrene Manufacturing Company of Delaware filed a patent to use carbon tetrachloride to extinguish fires.[9] The liquid was vaporized by the heat of combustion and extinguished flames, an early form of gaseous fire suppression. At the time it was believed the gas simply displaced oxygen in the area near the fire, but later research found that the gas actually inhibits the chemical chain reaction of the combustion process.
In 1911, Pyrene patented a small, portable extinguisher that used the chemical.[10] The extinguisher consisted of a brass bottle with an integrated handpump that was used to expel a jet of liquid toward the fire. As the container was unpressurized, it could easily be refilled after use.[11] Carbon tetrachloride was suitable for liquid and electrical fires and the extinguishers were often carried on aircraft or motor vehicles.
In the first half of the 20th century, another common fire extinguisher was a single-use, sealed glass globe known as a "fire grenade," filled with either carbon tetrachloride or salt water. The bulb could be thrown at the base of the flames to quench the fire. The carbon tetrachloride type could also be installed in a spring-loaded wall fixture with a solder-based restraint. When the solder melted by high heat, the spring would either break the globe or launch it out of the bracket, allowing the extinguishing agent to be automatically dispersed into the fire. A well-known brand was the "Red Comet," which was variously manufactured with other fire-fighting equipment in the Denver, Colorado area by the Red Comet Manufacturing Company from its founding in 1919 until manufacturing operations were closed in the early 1980s.[12]
Carbon tetrachloride was widely used as a dry cleaning solvent, as a refrigerant, and in lava lamps.[13]
One specialty use of carbon tetrachloride was in stamp collecting, to reveal watermarks on postage stamps without damaging them. A small amount of the liquid was placed on the back of a stamp, sitting in a black glass or obsidian tray. The letters or design of the watermark could then be clearly seen.
Carbon tetrachloride is one of the most potent hepatotoxins (toxic to the liver), so much so that it is widely used in scientific research to evaluate hepatoprotective agents.[7][14]Exposure to high concentrations of carbon tetrachloride (including vapor) can affect the central nervous system, degenerate the liver[14] and kidneys,[15] and prolonged exposure may lead to coma or death.[16] Chronic exposure to carbon tetrachloride can cause liver[17][18] and kidney damage and could result in cancer.[19] See safety data sheets.[20]
The effects of carbon tetrachloride on human health and the environment have been assessed under REACH in 2012 in the context of the substance evaluation by France. Thereafter, further information has been requested from the registrants. Later this decision was reversed.[21]
In 2008, a study of common cleaning products found the presence of carbon tetrachloride in "very high concentrations" (up to 101 mg/m3) as a result of manufacturers' mixing of surfactants or soap with sodium hypochlorite (bleach).[22]
Like many other volatile substances, carbon tetrachloride is prone to misuse by inhalation, due to its possible depressant and/or dissociative effect upon the central nervous system. Use of carbon tetrachloride in this manner presents serious health risks, and may result in toxic effects described above.
Carbon tetrachloride is also both ozone-depleting[23] and a greenhouse gas.[24] However, since 1992[25] its atmospheric concentrations have been in decline for the reasons described above (see also the atmospheric time-series figure). CCl4 has an atmospheric lifetime of 85 years.[26]
Under high temperatures in air, it forms poisonous phosgene.
Halomethanes
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| Monosubstituted |
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| Disubstituted |
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| Trisubstituted |
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| Tetrasubstituted |
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* Chiral compound.
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Inorganic compounds of carbon and related ions
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| Compounds |
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| Carbon ions |
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| Oxides and related |
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| Authority control |
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| リンク元 | 「四塩化炭素」 |
| 関連記事 | 「CC」「CCL4」 |