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Carbon tetrachloride
Carbon Tetrachloride.svg
Carbon-tetrachloride-3D-vdW.png
IUPAC name
Other names 1,1,1,1-Tetrachloromethane, Benziform, Benzinoform, Carbon chloride, Carbon tet, Freon 10, Halon 104, Methane tetrachloride, Perchloromethane, Tetraform, Tetrasol
Identifiers
CAS number 56-23-5 Yes check.svgY
PubChem 5943
EC number 200-262-8
UN number 1846
KEGG C07561
ChEBI 27385
RTECS number FG4900000
SMILES
InChI
InChI key VZGDMQKNWNREIO-UHFFFAOYAV
ChemSpider ID 5730
Properties
Molecular formula CCl4
Molar mass 153.82 g/mol
Appearance colourless liquid
ether-like odor
Density 1.5867 g/cm3, liquid

1.831 g.cm-3 at -186 °C (solid)
1.809 g.cm-3 at -80 °C (solid)

Melting point

-22.92 °C (250 K)

Boiling point

76.72 °C (350 K)

Solubility in water 785–800 mg/L at 25 °C
Solubility soluble in alcohol, ether, chloroform, benzene
log P 2.64
Vapor pressure 11.94 kPa at 20 °C
Refractive index (nD) 1.4601
Structure
Crystal structure Monoclinic
Molecular shape Tetrahedral
Hazards
MSDS External MSDS
EU Index 602-008-00-5
EU classification Carc. Cat. 3
Toxic (T)
Dangerous for the environment (N)
R-phrases R23/24/25, R40, R48/23, R59, R52/53
S-phrases (S1/2), S23, S36/37, S45, S59, S61
NFPA 704
NFPA 704.svg
0
3
0
 
Flash point Not flammable
Autoignition
temperature
982 °C
LD50 2350 mg/kg
Related compounds
Related chloromethanes Chloromethane
Dichloromethane
Chloroform
Related compounds Tetrafluoromethane
Tetrabromomethane
Tetraiodomethane
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Carbon tetrachloride, also known by many other names (see Table) is the organic compound with the 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.

Both carbon tetrachloride and tetrachloromethane are acceptable names under IUPAC nomenclature. Colloquially, it is called "carbon tet".

Contents

History and synthesis

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.[1]

Carbon tetrachloride was originally synthesised by the French chemist Henri Victor Regnault in 1839 by the reaction of chloroform with chlorine, from the ,[2] but now it is mainly produced from methane:

CH4 + 4 Cl2 → CCl4 + 4 HCl

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:"

C2Cl6 + Cl2 → 2 CCl4

Prior to the 1950s, carbon tetrachloride was manufactured by the chlorination of carbon disulfide at 105 to 130 °C:[1]

CS2 + 3Cl2 → CCl4 + S2Cl2

Properties

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 having a smell characteristic of other chlorinated solvents, somewhat similar to the tetrachloroethylene smell reminiscent of dry cleaners' shops.

Solid tetrachloromethane has 2 polymorphs: crystalline II below -47.5 °C (225.6 K) and crystalline I above -47.5 °C.[3]

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°.[4]

Uses

A brass, carbon-tetrachloride, fire extinguisher.

In the early 20th century, carbon tetrachloride was widely used as a dry cleaning solvent, as a refrigerant, and in lava lamps.[5] Small carbon tetrachloride fire extinguishers were widely used and took the form of a brass bottle with a hand pump to expel the liquid.

However, once it became apparent that carbon tetrachloride exposure had severe adverse health effects, safer alternatives such as tetrachloroethylene were found for these applications, and its use in these roles declined from about 1940 onward. Carbon tetrachloride persisted as a pesticide to kill insects in stored grain, but in 1970, it was banned in consumer products in the United States.

One specialty use of "carbon tet" was by stamp collectors to reveal watermarks on the backs of postage stamps. 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 detected.

Prior to the Montreal Protocol, large quantities of carbon tetrachloride were used to produce the freon refrigerants R-11 (trichlorofluoromethane) and R-12 (dichlorodifluoromethane). However, these refrigerants are now believed to 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.

Carbon tetrachloride is one of the most potent hepatotoxins (toxic to the liver), and is widely used in scientific research to evaluate hepatoprotective agents.[6][7]

Reactivity

Carbon tetrachloride has practically no flammability at lower temperatures. Under high temperatures in air, it forms poisonous phosgene.

Because it has no C-H bonds, carbon tetrachloride does not easily undergo free-radical reactions. Hence it is a useful solvent for halogenations either by the elemental halogen, or by a halogenation reagent such as N-bromosuccinimide.

In organic chemistry, carbon tetrachloride serves as a source of chlorine in the Appel reaction.

Solvent

It is used as a solvent in synthetic chemistry research, but because of its adverse health effects, it is no longer commonly used, and chemists generally try to replace it with other solvents. 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. However, carbon tetrachloride is toxic, and its dissolving power is low.[8] Its use has been largely superseded by deuterated solvents, which offer superior solvating properties and allow for deuterium lock by the spectrometer. Use of carbon tetrachloride in determination of oil has been replaced by various other solvents[6].

Safety

Exposure to high concentrations of carbon tetrachloride (including vapor) can affect the central nervous system, degenerate the liver[7] and kidneys[9] and may result (after prolonged exposure) in coma and even death.[10] Chronic exposure to carbon tetrachloride can cause liver[11][12] and kidney damage and could result in cancer.[13] More information can be found in Material safety data sheets.

In 2008, a study of common cleaning products found the presence of carbon tetrachloride in "very high concentrations" (up to 101 mg m−3) as a result of manufacturers' mixing of surfactants or soap with sodium hypochlorite (bleach).[14]

Time-series of atmospheric concentrations of CCl4 (Walker et al., 2000).

Carbon tetrachloride is also both ozone-depleting[15] and a greenhouse gas.[16] However, since 1992[17] its atmospheric concentrations have been in decline for the reasons described above (see also the atmospheric time-series figure).

References

  1. ^ a b Manfred Rossberg, Wilhelm Lendle, Gerhard Pfleiderer, Adolf Tögel, Eberhard-Ludwig Dreher, Ernst Langer, Heinz Jaerts, Peter Kleinschmidt, Heinz Strack, Richard Cook, Uwe Beck, Karl-August Lipper, Theodore R. Torkelson, Eckhard Löser, Klaus K. Beutel, “Chlorinated Hydrocarbons” in Ullmann's Encyclopedia of Industrial Chemistry, 2006 Wiley-VCH, Weinheim.doi:10.1002/14356007.a06_233.pub2
  2. ^ V. Regnault (1839). "Ueber die Chlorverbindungen des Kohlenstoffs, C2Cl2 und CCl2". Annalen der Pharmacie 30 (3): 350. doi:10.1002/jlac.18390300310.  
  3. ^ Carbon tetrachloride
  4. ^ F. Brezina, J. Mollin, R. Pastorek, Z. Sindelar. Chemicke tabulky anorganickych sloucenin (Chemical tables of inorganic compounds). SNTL, 1986.
  5. ^ Doherty RE (2000). "A History of the Production and Use of Carbon Tetrachloride, Tetrachloroethylene, Trichloroethylene and 1,1,1-Trichloroethane in the United States: Part 1—Historical Background; Carbon Tetrachloride and Tetrachloroethylene". Environmental Forensics 1 (1): 69–81. doi:10.1006/enfo.2000.0010.  
  6. ^ a b Use of Ozone Depleting Substances in Laboratories. TemaNord 516/2003.
  7. ^ a b Seifert WF, Bosma A, Brouwer A, et al (January 1994). "Vitamin A deficiency potentiates carbon tetrachloride-induced liver fibrosis in rats". Hepatology 19 (1): 193–201. doi:10.1002/hep.1840190129. PMID 8276355.  
  8. ^ W. Reusch. "Introduction to Nuclear Magnetic Resonance Spectroscopy". Virtual Textbook of Organic Chemistry. Michigan State University. http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy/nmr/nmr1.htm.  
  9. ^ Liu KX, Kato Y, Yamazaki M, Higuchi O, Nakamura T, Sugiyama Y (April 1993). "Decrease in the hepatic clearance of hepatocyte growth factor in carbon tetrachloride-intoxicated rats". Hepatology 17 (4): 651–60. doi:10.1002/hep.1840170420. PMID 8477970.  
  10. ^ Recknagel R.O., Glende E.A., Dolak J.A., Waller R.L. (1989). "Mechanism of Carbon-tetrachloride Toxicity". Pharmacology Therapeutics 43 (43): 139–154. doi:10.1016/0163-7258(89)90050-8.  
  11. ^ Recknagel RO (June 1967). "Carbon tetrachloride hepatotoxicity". Pharmacol. Rev. 19 (2): 145–208. PMID 4859860. http://pharmrev.aspetjournals.org/cgi/pmidlookup?view=long&pmid=4859860.  
  12. ^ Masuda Y (October 2006). "[Learning toxicology from carbon tetrachloride-induced hepatotoxicity"] (in Japanese) (). Yakugaku Zasshi 126 (10): 885–99. doi:10.1248/yakushi.126.885. PMID 17016019. http://joi.jlc.jst.go.jp/JST.JSTAGE/yakushi/126.885?from=PubMed&lang=en.  
  13. ^ Rood AS, McGavran PD, Aanenson JW, Till JE (August 2001). "Stochastic estimates of exposure and cancer risk from carbon tetrachloride released to the air from the rocky flats plant". Risk Anal. 21 (4): 675–95. doi:10.1111/0272-4332.214143. PMID 11726020.  
  14. ^ Odabasi M (2008). "Halogenated Volatile Organic Compounds from the Use of Chlorine-Bleach-Containing Household Products". Environmental Science & Technology 42 (5): 1445–51. doi:10.1021/es702355u.  
  15. ^ Fraser P. (1997). "Chemistry of stratospheric ozone and ozone depletion". Australian Meteorological Magazine 46 (3): 185–193.  
  16. ^ Evans WFJ, Puckrin E (1996). "A measurement of the greenhouse radiation associated with carbon tetrachloride (CCl4)". Geophysical Research Letters 23 (14): 1769–72. doi:10.1029/96GL01258.  
  17. ^ Walker, S. J., R. F. Weiss & P. K. Salameh (2000). "Reconstructed histories of the annual mean atmospheric mole fractions for the halocarbons CFC-11, CFC-12, CFC-113 and carbon tetrachloride". Journal of Geophysical Research 105: 14285–96. doi:10.1029/1999JC900273.  

External links

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Simple English

[[File:|thumb|Carbon tetrachloride structure]] Carbon tetrachloride, also known as carbon tet or Freon 10, is a chemical compound. Its chemical formula is CCl4. It contains carbon in its +4 oxidation state and chloride ions.

Contents

Properties

It is a colorless liquid. It smells like ether. It evaporates quite quickly. It can dissolve fats and oils as well as other stuff such as iodine. It doesn't burn, but it does make phosgene when heated to a high tempature.

Preparation

It is made by reacting methane with chlorine. This reaction is similar to the burning of methane (reaction of methane with oxygen). Hydrogen chloride is a byproduct (left over substance). It used to be made by reacting carbon disulfide with chlorine. This reaction would produce sulfur(I) chloride.

Uses

The uses of carbon tetrachloride have been diminished lately because people think it might damage the ozone layer in the sky that removes ultraviolet rays from the earth. Without ozone, people would get skin cancer much more. It was used as a fire extinguisher. It was also used to make freon.

Safety

Carbon tetrachloride is very toxic to the liver and so is used to test for medicines that protect the liver. It can cause cancer if one is exposed to it a lot.

See also


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