Carbon tetrachloride

Carbon tetrachloride, also known by many other names (the most notable being tetrachloromethane, also recognised 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 is a colourless liquid with a "sweet" smell that can be detected at low levels. It has practically no flammability at lower temperatures. It was formerly widely used in fire extinguishers, as a precursor to refrigerants and as a cleaning agent, but has since been phased out because of toxicity and safety concerns. Exposure to high concentrations of carbon tetrachloride (including vapor) can affect the central nervous system, degenerate the liver and kidneys. Prolonged exposure can be fatal.

Carbon tetrachloride
Structural formula of carbon tetrachloride
Space-filling model carbon tetrachloride
Carbon tetrachloride
Names
IUPAC name
Carbon tetrachloride, Tetrachloromethane
Other names
Benziform, benzinoform, carbon chloride, carbon tet., Freon-10, Refrigerant-10, Halon-104, methane tetrachloride, methyl tetrachloride, perchloromethane, Tetraform, Tetrasol
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.239
EC Number
  • 200-262-8
KEGG
RTECS number
  • FG4900000
UNII
UN number 1846
Properties
CCl4
Molar mass 153.81 g·mol−1
Appearance Colourless liquid
Odor Sweet, ether-like odor
Density 1.5867 g·cm−3 (liquid)

1.831 g·cm−3 at −186 °C (solid)
1.809 g·cm−3 at −80 °C (solid)

Melting point −22.92 °C (−9.26 °F; 250.23 K)
Boiling point 76.72 °C (170.10 °F; 349.87 K)
0.097 g/100 mL (0 °C)
0.081 g/100 mL (25 °C)
Solubility Soluble in alcohol, ether, chloroform, benzene, naphtha, CS2, formic acid
log P 2.64
Vapor pressure 11.94 kPa at 20 °C
2.76×10−2 atm-cu m/mol
−66.60×10−6 cm3/mol
Thermal conductivity 0.1036 W m-1 K-1 (300 K)[1]
1.4607
Viscosity 0.86 mPa·s[2]
0 D
Structure
Monoclinic
Tetragonal
Tetrahedral
0 D
Thermochemistry
132.6 J/mol·K
214.42 J/mol·K
−139.3 kJ/mol
−686 kJ/mol
Hazards
Safety data sheet See: data page
ICSC 0024
Toxic T Dangerous for the Environment (Nature) N
R-phrases (outdated) R23/24/25, R40, R48/23, R59, R52/53
S-phrases (outdated) (S1/2), S23, S36/37, S45, S59, S61
NFPA 704
Flammability code 0: Will not burn. E.g. waterHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
3
1
Flash point <982 °C
982 °C (1,800 °F; 1,255 K)
Lethal dose or concentration (LD, LC):
2350 mg/kg
5400 ppm (mammal)
8000 ppm (rat, 4 hr)
9526 ppm (mouse, 8 hr)[4]
1000 ppm (human)
20,000 ppm (guinea pig, 2 hr)
38,110 ppm (cat, 2 hr)
50,000 ppm (human, 5 min)
14,620 ppm (dog, 8 hr)[4]
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 10 ppm C 25 ppm 200 ppm (5-minute maximum peak in any 4 hours)[3]
REL (Recommended)
Ca ST 2 ppm (12.6 mg/m3) [60-minute][3]
IDLH (Immediate danger)
200 ppm[3]
Related compounds
Other cations
Silicon tetrachloride
Germanium tetrachloride
Tin tetrachloride
Lead tetrachloride
Related chloromethanes
Chloromethane
Dichloromethane
Chloroform
Related compounds
Tetrafluoromethane
Tetrabromomethane
Tetraiodomethane
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Thermodynamic
data
Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

History and synthesis

Carbon tetrachloride was originally synthesized by the French chemist Henri Victor Regnault in 1839 by the reaction of chloroform with chlorine,[5] 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:[6]

CS2 + 3Cl2 → CCl4 + S2Cl2

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.[6]

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 such as 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.[7] 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°.[8]

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.

Uses

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

One specialty use of carbon tetrachloride is 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.

Historic uses

Carbon tetrachloride 1930s fire extinguisher
A brass Pyrene carbon-tetrachloride fire extinguisher
Snohomish - Blackman House Museum - Comet fire extinguisher 02A
A Red Comet brand glass globe ("fire grenade") containing carbon-tetrachloride

Carbon tetrachloride was widely used as a dry cleaning solvent, as a refrigerant, and in lava lamps.[9] In case of the latter, carbon tetrachloride is a key ingredient that adds weight to the otherwise buoyant wax.

Solvent

It once was a popular solvent in organic chemistry, but, because of its adverse health effects, it is rarely used today.[10] 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.[11] 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.[10] 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).

Fire suppression

In 1910, the Pyrene Manufacturing Company of Delaware filed a patent to use carbon tetrachloride to extinguish fires.[12] 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.[13] 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.[14] 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.[15]

Refrigerants

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 made from heavy chlorine-37 has been used in the detection of neutrinos.

Safety

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

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.[10][16] Exposure to high concentrations of carbon tetrachloride (including vapor) can affect the central nervous system, degenerate the liver[16] and kidneys,[17] and prolonged exposure may lead to coma or death.[18] Chronic exposure to carbon tetrachloride can cause liver[19][20] and kidney damage and could result in cancer.[21] See safety data sheets.[22]

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.[23]

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).[24]

Carbon tetrachloride is also both ozone-depleting[25] and a greenhouse gas.[26] However, since 1992[27] 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.[28]

Under high temperatures in air, it forms poisonous phosgene.

References

  1. ^ Touloukian, Y.S., Liley, P.E., and Saxena, S.C. Thermophysical properties of matter - the TPRC data series. Volume 3. Thermal conductivity - nonmetallic liquids and gases. Data book. 1970.
  2. ^ Reid, Robert C.; Prausnitz, John M.; Poling, Bruce E. (1987), The Properties of Gases and Liquids, McGraw-Hill Book Company, p. 442, ISBN 0-07-051799-1
  3. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0107". National Institute for Occupational Safety and Health (NIOSH).
  4. ^ a b "Carbon tetrachloride". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  5. ^ V. Regnault (1839) "Sur les chlorures de carbone CCl et CCl2" (On the chlorides of carbon CCl and CCl2 ), Annales de Chimie et de Physique, vol. 70, pages 104-107. Reprinted in German as: V. Regnault (1839). "Ueber die Chlorverbindungen des Kohlenstoffs, C2Cl2 und CCl2". Annalen der Pharmacie. 30 (3): 350–352. doi:10.1002/jlac.18390300310.
  6. ^ 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
  7. ^ "Carbon Tetrachloride". webbook.nist.gov. Archived from the original on 30 June 2017. Retrieved 28 April 2018.
  8. ^ F. Brezina, J. Mollin, R. Pastorek, Z. Sindelar. Chemicke tabulky anorganickych sloucenin (Chemical tables of inorganic compounds). SNTL, 1986.
  9. ^ Doherty R. E. (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 (2): 69–81. doi:10.1006/enfo.2000.0010.
  10. ^ a b c Use of Ozone Depleting Substances in Laboratories. TemaNord 516/2003. Archived February 27, 2008, at the Wayback Machine
  11. ^ W. Reusch. "Introduction to Nuclear Magnetic Resonance Spectroscopy". Virtual Textbook of Organic Chemistry. Michigan State University. Archived from the original on August 31, 2006.
  12. ^ U.S. Patent 1,010,870, filed April 5, 1910.
  13. ^ U.S. Patent 1,105,263, filed Jan 7, 1911.
  14. ^ "Pyrene Fire Extinguishers". Vintage Fire Extinguishers. Archived from the original on 25 March 2010. Retrieved 23 December 2009.
  15. ^ "Red Comet Manufacturing Company". City of Littleton, CO. Archived from the original on 1 October 2016. Retrieved 30 September 2016.
  16. ^ a b Seifert W. F., 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.CS1 maint: uses authors parameter (link)
  17. ^ Liu K. X., 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.CS1 maint: uses authors parameter (link)
  18. ^ 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.
  19. ^ Recknagel R. O. (June 1967). "Carbon tetrachloride hepatotoxicity". Pharmacol. Rev. 19 (2): 145–208. PMID 4859860.
  20. ^ Masuda Y. (October 2006). "[Learning toxicology from carbon tetrachloride-induced hepatotoxicity]". Yakugaku Zasshi (in Japanese). 126 (10): 885–99. doi:10.1248/yakushi.126.885. PMID 17016019.
  21. ^ Rood A. S., McGavran P. D., Aanenson J. W., Till J. E. (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.CS1 maint: uses authors parameter (link)
  22. ^ Material Safety Data Sheet, Carbon tetrachloride Archived 2010-09-13 at the Wayback Machine at Fisher Scientific.
  23. ^ "Substance evaluation - CoRAP - ECHA". echa.europa.eu. Archived from the original on 20 August 2016. Retrieved 28 April 2018.
  24. ^ Odabasi M. (2008). "Halogenated Volatile Organic Compounds from the Use of Chlorine-Bleach-Containing Household Products". Environmental Science & Technology. 42 (5): 1445–51. Bibcode:2008EnST...42.1445O. doi:10.1021/es702355u.
  25. ^ Fraser P. (1997). "Chemistry of stratospheric ozone and ozone depletion". Australian Meteorological Magazine. 46 (3): 185–193.
  26. ^ Evans W. F. J., Puckrin E. (1996). "A measurement of the greenhouse radiation associated with carbon tetrachloride (CCl4)". Geophysical Research Letters. 23 (14): 1769–72. Bibcode:1996GeoRL..23.1769E. doi:10.1029/96GL01258.CS1 maint: uses authors parameter (link)
  27. ^ Walker, S. J.; Weiss R. F. & Salameh P. K. (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 (C6): 14285–96. Bibcode:2000JGR...10514285W. doi:10.1029/1999JC900273.
  28. ^ The Atlas of Climate Change (2006) by Kirstin Dow and Thomas E. Downing ISBN 978-0-520-25558-6

External links

Appel reaction

The Appel reaction is an organic reaction that converts an alcohol into an alkyl chloride using triphenylphosphine and carbon tetrachloride. The use of carbon tetrabromide or bromine as a halide source will yield alkyl bromides, whereas using carbon tetraiodide, methyl iodide or iodine gives alkyl iodides. The reaction is credited to and named after Rolf Appel, it had however been described earlier. The use of this reaction is becoming less common, due to carbon tetrachloride being restricted under the Montreal protocol.

Drawbacks to the reaction are the use of toxic halogenating agents and the coproduction of organophosphorus product that must be separated from the organic product. The phosphorus reagent can be used in catalytic quantities. The corresponding alkyl bromide can also be synthesised by addition of lithium bromide as a source of bromide ions.

Azeotrope tables

This page contains tables of azeotrope data for various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity of the mixture. Boiling points are reported at a pressure of 760 mm Hg unless otherwise stated. Where the mixture separates into layers, values are shown for upper (U) and lower (L) layers.

The data were obtained from Lange's 10th edition and CRC Handbook of Chemistry and Physics 44th edition unless otherwise noted (see color code table).

A list of 15825 binary and ternary mixtures was collated and published by the American Chemical Society. An azeotrope databank is also available online through the University of Edinburgh.

Benzoquinonetetracarboxylic dianhydride

Benzoquinonetetracarboxylic dianhydride is an organic compound with formula C10O8 (an oxide of carbon) which can be seen as the result of removing two molecules of water H2O from benzoquinonetetracarboxylic acid.

It is a red solid, stable in dry air up to 140 °C and insoluble in ether, carbon tetrachloride, dichloromethane, and carbon disulfide. It reacts with acetone, ethyl acetate, tetrahydrofuran, ethanol, and water. It dissolves in methylated derivatives of benzene to give solutions ranging from orange to violet. When the molecule is exposed to moist air it quickly turns blue.

The compound was synthesized in 1963 by P. R. Hammond who claimed it was "one of

the strongest π-electron acceptors so far described."

Binary phase

In materials chemistry, a binary phase is a chemical compound containing two different elements. Some binary phases compounds are molecular, e.g. carbon tetrachloride (CCl4). More typically binary phase refers to extended solids. Famous examples are the two polymorphs of zinc sulfide.Phases with higher degrees of complexity feature more elements, e.g. three elements in ternary phases, four elements in quaternary phases,

Bromine test

In organic chemistry, the bromine test is a qualitative test for the presence of unsaturation (carbon-to-carbon double or triple bonds) , phenols and anilines.

An unknown sample is treated with a small amount of elemental bromine in an organic solvent, being

as dichloromethane or carbon tetrachloride. Presence of unsaturation and/or phenol or aniline in the sample is shown by disappearance of the deep brown coloration of bromine when it has reacted with the unknown sample. The formation of a brominated phenol (i.e. 2,4,6-tribromophenol) or aniline(i.e. 2,4,6-tribromoaniline) in form of a white precipitate indicates that the unknown was a phenol or aniline. The more unsaturated an unknown is, the more bromine it reacts with, and the less coloured the solution will appear.Should the brown colour not disappear, possibly due to the presence of an alkane which doesn't react, or reacts very slowly with, bromine, the potassium permanganate test should be performed, in order to determine the presence or absence of the alkene. The iodine value is a way to determine the presence of unsaturation quantitatively.

The bromine test is a simple qualitative test. Modern spectroscopic methods (e.g. NMR and infrared spectroscopy) are better at determining the structural features and identity of unknown compounds.

Bromochloromethane

Bromochloromethane or methylene bromochloride and Halon 1011 is a mixed halomethane. It is a heavy low-viscosity liquid with refractive index 1.4808.

It was invented for use in fire extinguishers by the Germans during the mid-1940s, in an attempt to create a less-toxic, more effective alternative to carbon tetrachloride. This was a concern in aircraft and tanks as carbon tetrachloride produced highly toxic by-products when discharged onto a fire. CBM was slightly less toxic, and used up until the late 1960s, being officially banned by the NFPA for use in fire extinguishers in 1969, as safer and more effective agents such as halon 1211 and 1301 were developed. Due to its ozone depletion potential its production was banned from January 1, 2002, at the Eleventh Meeting of the Parties for the Montreal Protocol on Substances that Deplete the Ozone Layer.

Its biodegradation is catalyzed by the hydrolase enzyme alkylhalidase:

CH2BrCl + H2O → CH2O + HBr + HCl

Carbon tetrachloride (data page)

This page provides supplementary chemical data on carbon tetrachloride.

Hafnium dioxide

Hafnium(IV) oxide is the inorganic compound with the formula HfO2. Also known as hafnia, this colourless solid is one of the most common and stable compounds of hafnium. It is an electrical insulator with a band gap of 5.3~5.7 eV. Hafnium dioxide is an intermediate in some processes that give hafnium metal.

Hafnium(IV) oxide is quite inert. It reacts with strong acids such as concentrated sulfuric acid and with strong bases. It dissolves slowly in hydrofluoric acid to give fluorohafnate anions. At elevated temperatures, it reacts with chlorine in the presence of graphite or carbon tetrachloride to give hafnium tetrachloride.

Hepatotoxin

A hepatotoxin (Gr., hepato = liver) is a toxic chemical substance that damages the liver.

It can be a side-effect of medication, or found naturally, as microcystins, or in laboratory environments.

The effects of hepatotoxins depend on the amount, point of entry and distribution speed of the [toxin], and on the health of the person.

Hexachlorobutadiene

Hexachlorobutadiene, Cl2C=C(Cl)C(Cl)=CCl2, is a colorless liquid at room temperature that has an odor similar to that of turpentine. It is a chlorinated aliphatic diene with niche applications but is most commonly used as a solvent for other chlorine-containing compounds.

Kharasch addition

The Kharasch addition is an organic reaction and a metal-catalysed free radical addition of CXCl3 compounds (X = Cl, Br, H) to alkenes. The reaction was discovered by Morris S. Kharasch in the 1940s.The basic reaction scheme runs as follows:

R2C=CH2 + R'X → R2CX-CH2R':and proceeds through the CXCl2 free radical. Examples of organohalides are carbon tetrachloride and chloroform. The addition is an anti-Markovnikov addition. Early work linked the addition to olefin polymerization and is therefore considered a first step into what was to become atom transfer radical polymerization.

An example of Karasch addition is the synthesis of 1,1,3-trichloro-n-nonane from 1-octene, chloroform and [[ferric chloride](FeCl2)].

Lava lamp

A lava lamp (or astro lamp) is a decorative lamp, invented in 1963 by British entrepreneur Edward Craven Walker the founder of the British lighting company Mathmos. The lamp consists of a bolus of a special coloured wax mixture inside a glass vessel, the remainder of which contains clear or translucent liquid; the vessel is then placed on a box containing an incandescent light bulb whose heat causes temporary reductions in the density of the wax and surface tension of the liquid. The warmed wax rises through the surrounding liquid, cools, loses its buoyancy, and falls back to the bottom of the vessel in a cycle that is visually suggestive of pāhoehoe lava, hence the name. The lamps are designed in a variety of styles and colours.

Perchloromethyl mercaptan

Perchloromethyl mercaptan is the organosulfur compound with the formula CCl3SCl. It is mainly used as an intermediate for the synthesis of dyes and fungicides (captan, folpet). It is a colorless oil, although commercial samples are yellowish. It is insoluble in water but soluble in organic solvents. It has a foul, unbearable, acrid odor. Perchloromethyl mercaptan is the original name. The systematic name is trichloromethanesulfenyl chloride, because the compound is a sulfenyl chloride, not a mercaptan.

Pseudomonas stutzeri

Pseudomonas stutzeri is a Gram-negative, rod-shaped, motile, single polar-flagellated, soil bacterium first isolated from human spinal fluid. It is a denitrifying bacterium, and strain KC of P. stutzeri may be used for bioremediation as it is able to degrade carbon tetrachloride. It is also an opportunistic pathogen in clinical settings, although infections are rare. Based on 16S rRNA analysis, P. stutzeri has been placed in the P. stutzeri group, to which it lends its name.

Pyrene (disambiguation)

Pyrene may refer to:

Pyrene, a chemical compound.

Carbon tetrachloride, pyrene is the brand name used by the Pyrene Manufacturing Company for Carbon tetrachloride.

Pyrene (mythology), consort of Ares and the mother of Cycnus in Greek mythology

Pyrene, a Celtic city near the sources of the Danube mentioned by Herodotus: see Heuneburg

The Pyrene Company Limited, a manufacturer of firefighting equipment

The Pyrene Building, Golden Mile (Brentford), a noted former Pyrene Company factory in London, England in the Art Deco style

Pyrene (gastropod), a genus of sea snails from the family Columbellidae

Pyrena, a kind of nutlet

Pyrenees, a mountain range between France and Spain

Technetium(IV) chloride

Technetium(IV) chloride is the chemical compound composed of technetium and chlorine with the formula TcCl4. It was discovered in 1957 as the first binary halide of technetium. It is the highest oxidation binary chloride of technetium that has been isolated in the solid-state. It is volatile at elevated temperatures and its volatility has been used for separating technetium from other metal chlorides.Colloidal solutions of technetium(IV) chloride are oxidized to form Tc(VII) ions when exposed to gamma rays.

Technetium tetrachloride can be synthesized from the reaction of Cl2(g) with technetium metal at elevated temperatures between 300-500 °C:Tc + 2 Cl2 → TcCl4Technetium tetrachloride has also been prepared from the reaction of ditechnetium heptoxide with carbon tetrachloride in a bomb reaction vessel at elevated temperature and pressure:

Tc2O7 + 7 CCl4 → 2 TcCl4 + 7 COCl2 + 3 Cl2At 450 °C under vacuum, TcCl4 decomposes to TcCl3 and TcCl2.

Tellimagrandin I

Tellimagrandin I is an ellagitannin found in plants, such as Cornus canadensis, Eucalyptus globulus, Melaleuca styphelioides, Rosa rugosa, and walnut. It is composed of two galloyl and one hexahydroxydiphenyl groups bound to a glucose residue. It differs from Tellimagrandin II only by a hydroxyl group instead of a third galloyl group. It is also structurally similar to punigluconin and pedunculagin, two more ellagitannin monomers.

Tellimagrandin I has been shown to restore antioxidant enzyme activity in glucose- and oxalate-challenged rat cells and affects Cu(II)- and Fe(II)-dependent DNA strand breaks. It has hepatoprotective effects on carbon tetrachloride- and d-galactosamine-stressed HepG2 cells and enhances peroxisomal fatty acid beta-oxidation in liver, increasing mRNA expression of PPAR alpha, ACOX1, and CPT1A. It enhances gap junction communication and reduces tumor phenotype in HeLa cells and inhibits invasion of HSV-1 and HCV similar to eugeniin and casuarictin.

Toxicodynamics

Toxicodynamics, termed pharmacodynamics in pharmacology, describes the dynamic interactions of a toxicant with a biological target and its biological effects. A biological target, also known as the site of action, can be binding proteins, ion channels, DNA, or a variety of other receptors. When a toxicant enters an organism, it can interact with these receptors and produce structural or functional alterations. The mechanism of action of the toxicant, as determined by a toxicant’s chemical properties, will determine what receptors are targeted and the overall toxic effect at the cellular level and organismal level.

Toxicants have been grouped together according to their chemical properties by way of quantitative structure-activity relationships (QSARs), which allows prediction of toxic action based on these properties. endocrine disrupting chemicals (EDCs) and carcinogens are examples of classes of toxicants that can act as QSARs. EDCs mimic or block transcriptional activation normally caused by natural steroid hormones. These types of chemicals can act on androgen receptors, estrogen receptors and thyroid hormone receptors. This mechanism can include such toxicants as dichlorodiphenyltrichloroethane (DDE) and polychlorinated biphenyls (PCBs). Another class of chemicals, carcinogens, are substances that cause cancer and can be classified as genotoxic or nongenotoxic carcinogens. These categories include toxicants such as polycyclic aromatic hydrocarbon (PAHs) and carbon tetrachloride (CCl4).

The process of toxicodynamics can be useful for application in environmental risk assessment by implementing toxicokinetic-toxicodynamic (TKTD) models. TKTD models include phenomenas such as time-varying exposure, carry-over toxicity, organism recovery time, effects of mixtures, and extrapolation to untested chemicals and species. Due to their advantages, these types of models may be more applicable for risk assessment than traditional modeling approaches.

Wohl–Ziegler bromination

The Wohl–Ziegler reaction

is a chemical reaction that involves the allylic or benzylic bromination of hydrocarbons using an N-bromosuccinimide and a radical initiator.

Best yields are achieved with N-bromosuccinimide in carbon tetrachloride solvent. Several reviews have been published.In a typical setup a stoichiometric amount of N-bromosuccinimide solution and a small quantity of initiator are added to a solution of the substrate in CCl4, and the reaction mixture is stirred and heated to the boiling point. Initiation of the reaction is indicated by more vigorous boiling; sometimes the heat source may need to be removed. Once all N-bromosuccinimide (which is denser than the solvent) has been converted to succinimide (which floats on top) the reaction has finished. Due to the high toxicity and ozone-depleting nature of carbon tetrachloride, trifluorotoluene has been proposed as an alternative solvent suitable for the Wohl-Ziegler bromination.The corresponding chlorination reaction cannot generally be achieved with N-chlorosuccinimide, although more specialized reagents have been developed, and the reaction can be achieved industrially with chlorine gas.

Unsubstituted
Monosubstituted
Disubstituted
Trisubstituted
Tetrasubstituted
Compounds
Carbon ions
Oxides and related

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