56-23-5 Usage
Chemical Description
Carbon tetrachloride is a colorless liquid that was once widely used as a solvent, but is now known to be toxic and carcinogenic.
Chemical Description
Carbon tetrachloride is used as a solvent.
Chemical Description
Carbon tetrachloride is used as a solvent in the chlorination of p-iodoanisole.
Chemical Description
Carbon tetrachloride is a colorless liquid used as a solvent and in fire extinguishers.
Chemical Description
Carbon tetrachloride is a nonflammable liquid used as a solvent and in fire extinguishers.
Uses
1. Used in Refrigerant and Propellant Production:
Carbon tetrachloride is used as a feedstock in the synthesis of chlorofluorocarbons (CFCs), which are primarily used as refrigerants and propellants for aerosol cans.
2. Used in Chemical Synthesis:
Carbon tetrachloride is used as a starting material in the manufacture of organic compounds and as a solvent in the production of paint, ink, plastics, semiconductors, and petrol additives.
3. Used in Petroleum Refining and Pharmaceutical Manufacturing:
It is also used in petroleum refining and pharmaceutical manufacturing as a solvent and a feedstock for the synthesis of other chemicals.
4. Used as a Solvent:
Carbon tetrachloride is used as a solvent for oils, fats, lacquers, varnishes, rubber waxes, resins, and benzyl resins. It is also used as a solvent in the dry cleaning industry and for degreasing purposes.
5. Used in Fire Extinguishers:
Due to its non-flammable nature, carbon tetrachloride has been used in fire extinguishers.
6. Used as a Grain Fumigant and Pesticide:
Carbon tetrachloride has been used as a grain fumigant to kill insects and as a pesticide.
7. Used in the Production of Semiconductors:
It is also used in the production of semiconductors.
However, it is important to note that due to its toxicity and classification as a carcinogen by the U.S. government, many of the consumer uses of carbon tetrachloride have been discontinued, and only industrial use remains. Additionally, the production and use of carbon tetrachloride have been decreasing due to the agreement reached in the Montreal Protocol for the reduction of environmental concentrations of ozone-depleting chemicals, including carbon tetrachloride.
Organic solvents
Carbon tetrachloride, also known as tetrachloromethane, has its molecule formula being CCl4. It appears as colorless liquid with the melting point of-23 ° C, boiling point of 76.8 ° C and the relative density of 1.5867. It can dissolve grease, paint, resin, rubber and many other substances, being commonly used organic solvent and extractant. It can also be used as dry cleaning agent. However, long-term exposure to carbon tetrachloride will irritate the skin, inhibit the central nervous system and cause damage to the liver and kidney. Therefore, the operator should pay special attention. Carbon tetrachloride is volatile with its vapor being heavier than air, being non-conductive and inflammable. When the carbon tetrachloride is heat to be evaporated to become heavy steam, the gas will cover the combustion products, so that the firing product is isolated from the air and the fire is extinguished. It is especially suitable for extinguishing oil fire and fire near the power. However, carbon tetrachloride, at high temperature (500 ℃ above), can react with water to produce highly toxic phosgene, so we should pay attention to ventilation for extinguishing fire.
carbon tetrachloride lewis structure
Chemical reaction
Carbon tetrachloride molecule exhibits tetrahedral structure, belonging to non-polar molecule. It chemical reactivity was inert, but being more active than chloroform. At 250 ℃ with the presence of water, it can react with some metals to produce carbon dioxide; Upon anhydrous condition, the reaction between carbon tetrachloride and metal is very slow.CCl4 + 2H2O→CO2 + 4HClCarbon tetrachloride is decomposed by water in the presence of metals such as aluminum and iron (catalyzed). If it is superheated steam, even without the presence of metal catalyst, carbon tetrachloride can also be decomposed to produce phosgene.CCl4 + H2O →COCl2 + 2HClIn the case of heating, carbon tetrachloride can have reaction with halogen salt, generating other kinds of tetrahalide. For example, its reaction with silver fluoride can generate carbon tetrafluoride; its reaction with aluminum bromide and calcium iodide can generate carbon tetrabromide and tetra-iodide.In the presence of trace amount of hydrogen chloride, the product can react with silver perchlorate, generating explosive compounds Cl3CClO4:CCl4 + AgClO4 → Cl3CClO4 + AgClIn the presence of antimony pentachloride catalyst, this product can react with hydrogen fluoride to generate fluoride methyl chloride, such as monofluorotrichloromethane, difluorodichloromethane, namely, Freon refrigerant.CCl4 + HF→CCl3F + HClCCl4 + 2HF→CCl2F2 + HClCarbon tetrachloride can react with sulfur at high temperatures (above 200 ° C) to produce carbon disulfide.CCl4 + 6S → CS2 + 2S2Cl2Under the catalysis of anhydrous aluminum chloride, carbon tetrachloride can react with benzene, generating triphenyl methane.Under the catalysis of iron or iron salt, heating to 330 ℃ can promote the oxidation of carbon tetrachloride decomposition, generating phosgene.2CCl4 + O2 →2COCl2 + 2Cl2
Preparation
Carbon tetrachloride, CCl4 (i.e., tetrachloromethane) is prepared by the action of chlorine on carbon disulphide in the presence of iodine, which acts as a catalyst.
CS2 + Cl2= CCl4 + S2Cl2
Carbon tetrachloride may also be prepared by the free radical substitution of the hydrogen atoms of methane by chlorine.
CH4 + 4Cl2 = CCl4 + 4HCl
The bonding in carbon tetrachloride is covalent, as in methane.
History
In the 1890s, commercial manufacturing processes were being investigated by the United Alkali Co. in England. At the same time it was also produced in Germany, exported to the United States, and retailed as a spotting agent under the trade name Carbona. Large-scale production of carbon tetrachloride in the United States commenced in the early 1900s. By 1914, annual production fell just short of 4500 metric tons and was used primarily for dry cleaning and for charging fire extinguishers. During World War I, U.S. production of carbon tetrachloride expanded greatly; its use was extended to grain fumigation and the rubber industry. In 1934 it was supplanted as the predominant dry-cleaning agent in the United States by perchloroethylene, which is much less toxic and more stable. During the years immediately preceding World War II, trichloroethylene began to displace carbon tetrachloride from its then extensive market in the United States as a metal degreasing solvent. Carbon tetrachloride is more difficult to recover from degreasing operations, more readily hydrolyzed, and more toxic than trichloroethylene C2HCl3. The demands of World War II stimulated production and marked the beginning of its use as the starting material for chlorofluoromethanes, by far the most important application for carbon tetrachloride.
Production Methods
Carbon tetrachloride is made by the reaction of carbon disulfide and chlorine in the presence of a catalyst, such as iron or antimony pentachloride:
CS2 + 3Cl2 → CCl4 + S2Cl2
Sulfur chloride is removed by treatment with caustic soda solution. The product is purified by distillation.
Alternatively, CCl4 may be prepared by heating a mixture of chlorine and methane at 250 to 400°C.
CH4 + 4Cl2 → CCl4 + 4HCl
Air & Water Reactions
Insoluble in water.
Reactivity Profile
Carbon tetrachloride is a commonly used liquid in fire extinguishers to combat small fires. Carbon tetrachloride has no flash point, Carbon tetrachloride is not flammable. However, when heated to decomposition, Carbon tetrachloride will emit fumes of extremely toxic phosgene and of hydrogen chloride. Forms explosive mixtures with chlorine trifluoride, calcium hypochlorite, decaborane, dinitrogen tetraoxide, fluorine. Forms impact-sensitive explosive mixtures with particles of many metals: lithium, sodium, potassium, beryllium, zinc, aluminum, barium. Vigorous exothermic reaction with allyl alcohol, boron trifluoride, diborane, disilane, aluminum chloride, dibenzoyl peroxide, potassium tert-butoxide, liquid oxygen, zirconium. [Bretherick, 5th ed., 1995, p. 666]. Potentially dangerous reaction with dimethylformamide or dimethylacetamide in presence of iron [Cardillo, P. et al., Ann. Chim. (Rome), 1984, 74, p. 129].
Hazard
Carbon tetrachloride is a poison and also a carcinogen. The acute toxicity of this compound in humans is of low order. However, the ingestion of the liquid can be fatal, death resulting from acute liver or kidney necrosis. (Patnaik, P. 1999. A Comprehensive Guide to the Hazardous Properties of Chemical Substances, 2nd ed. New York: John Wiley & Sons.) The acute poisoning effects are headache, dizziness, fatigue, stupor, nausea, vomiting, diarrhea, and liver damage. Chronic exposure can damage both liver and kidney. Carbon tetrachloride also is a suspected human carcinogen. It causes liver and thyroid cancers in experimental animals.
Health Hazard
Carbon tetrachloride exhibits low acute tox icity by all routes of exposure. The acute poisoning effects include dizziness, fatigue,headache, nervousness, stupor, nausea, vom iting, diarrhea, renal damage, and liverinjury. The dosages that produce toxic act ions in animals vary with the species. Theoral LD50 values in rats, rabbits, and mice are2800, 5760, and 8263 mg/kg, respectively(NIOSH 1986).Ingestion of carbon tetrachloride can befatal to humans, death resulting from acuteliver or kidney necrosis. Chronic exposuremay cause liver and kidney damage. Expo sure to a 10-ppm concentration for severalweeks produced accumulation of fat in the liv ers of experimental animals (ACGIH 1986).Substances such as ethanol and barbituratescause potentiation of toxicity of carbon tetra chloride. Skin contact can cause dermatitis.Azri and coworkers (1990) have investi gated carbon tetrachloride–induced hepato toxicity in rat liver slices. Liver slices frommale rats were incubated and exposed tocarbon tetrachloride vapors, and the degreeof injury to cellular tissue was determined.Covalent binding of CCl4 radical to proteinsand lipid molecules in a slice caused the cel lular injury. The toxicity depended on thevapor concentration and the time of expo sure. Azri and coworkers reported furtherthat rats pretreated with phenobarbital weremore rapidly intoxicated even at a lower con centration of carbon tetrachloride vapors. Onthe other hand, pretreatment with allyliso propylacetamide inhibited the toxicity of car bon tetrachloride.Carbon tetrachloride is a suspected humancarcinogen. Oral and subcutaneous adminis tration of this compound in rats caused liverand thyroid cancers in the animals.
Flammability and Explosibility
Carbon tetrachloride is noncombustible. Exposure to fire or high temperatures may
lead to formation of phosgene, a highly toxic gas.
Safety Profile
Also forms explosive mixtures with chlorine trifluoride, calcium hypochlorite (heatsensitive), calcium dtsllicide (frictionand pressuresensitive), triethyldialuminum trichloride (heatsensitive), decaborane(l4) (impact-sensitive), dinitrogen tetraoxide. Violent or explosive reaction on contact with fluorine. Forms explosive mixtures with ethylene between 25' and 105' and between 30 and 80 bar. Potentially explosive reaction on contact with boranes. 9:l mixtures of methanol and cCl4 react exothermically with aluminum, magnesium, or zinc. Potentially dangerous reaction with dimethyl formamide, 1,2,3,4,5,6 hexachlorocyclohexane, or dtmethylacetamide when iron is present as a catalyst. CCh has caused explosions when used as a fire extingusher on wax and uranium fires. Incompatible with aluminum trichloride, dtbenzoyl peroxide, potassiumtert-butoxide. Vigorous exothermic reaction with allyl alcohol, Al(C2H5)3, (benzoyl peroxide + C2H4), BrF3, diborane, dsilane, liquid O2, Pu, (AgClO4 + HCl), potassiumtert-butoxide, tetraethylenepentamine, tetrasilane, trisilane, Zr. When heated to decomposition it emits toxic fumes of Cl and phosgene. It has been banned from household use by the FDA.
Potential Exposure
Carbon tetrachloride, and organochlorine, is used as a solvent for oils, fats, lacquers, varnishes,
rubber, waxes, and resins. Fluorocarbons are chemically
synthesized from it. It is also used as an azeotropic drying
agent for spark plugs; a dry-cleaning agent; a fire extinguishing agent; a fumigant, and an anthelmintic agent. The
use of this solvent is widespread, and substitution of less
toxic solvents when technically possible is recommended.
Carcinogenicity
Carbon tetrachloride is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.
Source
Carbon tetrachloride is used in fumigant mixtures such as 1,2-dichloroethane (Granosan)
because it reduces the fire hazard (Worthing and Hance, 1991).
Environmental Fate
Biological. Carbon tetrachloride was degraded by denitrifying bacteria forming chloroform (Smith and Dragun, 1984). An anaerobic species of Clostridium biodegraded
carbon tetrachloride by reductive dechlorination yielding trichloromethane, dichloromethane and unidentified products (G?lli and McCarty, 1989). Chloroform also formed
by microbial degradation of carbon tetrachloride using denitrifying bacteria (Smith and
Dragun, 1984).
Carbon tetrachloride (5 and 10 mg/L) showed significant degradation with rapid
adaptation in a static-culture flask-screening test (settled domestic wastewater inoculum)
conducted at 25°C. Complete degradation was observed after 14 days of incubation (Tabak
et al., 1981).
Chemical/Physical. Under laboratory conditions, carbon tetrachloride partially hydrolyzed to chloroform and carbon dioxide (Smith and Dragun, 1984). Complete hydrolysis
yielded carbon dioxide and hydrochloric acid (Kollig, 1993). Carbon tetrachloride slowly
reacts with hydrogen sulfide in aqueous solution yielding carbon dioxide via the intermediate carbon disulfide. However, in the presence of two micaceous minerals (biotite and
vermiculite) and amorphous silica, the rate of transformation increased. At 25°C and a
hydrogen sulfide concentration of 1 mM, the half-lives for carbon tetrachloride were
calculated to be 2,600, 160 and 50 days for the silica, vermiculite and biotite studies,
respectively. In all three studies, the major transformation pathway is the formation of
carbon disulfide which undergoes hydrolysis yielding carbon dioxide (81–86% yield) and
hydrogen sulfide ions. Minor intermediates detected include chloroform (5–15% yield),carbon monoxide (1–2% yield) and a nonvolatile compound tentatively identified as formic
acid (3–6% yield) (Kriegman-King and Reinhard, 1992).
Anticipated products from the reaction of carbon tetrachloride with ozone or hydroxyl
radicals in the atmosphere are phosgene and chloride radicals (Cupitt, 1980). Phosgene is
hydrolyzed readily to hydrochloric acid and carbon dioxide (Morrison and Boyd, 1971).
Matheson and Tratnyek (1994) studied the reaction of fine-grained iron metal in an
anaerobic aqueous solution (15°C) containing carbon tetrachloride (151 μM). Initially,
carbon tetrachloride underwent rapid dehydrochlorination forming chloroform, which
further degraded to methylene chloride and chloride ions. The rate of reaction decreased
with each dehydrochlorination step. However, after 1 hour of mixing, the concentration
of carbon tetrachloride decreased from 151 to approximately 15 μM. No additional products were identified although the authors concluded that environmental circumstances may
exist where degradation of methylene chloride may occur. They also reported that reductive
dehalogenation of carbon tetrachloride and other chlorinated hydrocarbons used in this
study appears to take place in conjunction with the oxidative dissolution or corrosion of
the iron metal through a diffusion-limited surface reaction.
The evaporation half-life of carbon tetrachloride (1 mg/L) from water at 25°C using
a shallow-pitch propeller stirrer at 200 rpm at an average depth of 6.5 cm is 29 minutes
(Dilling, 1977).
storage
Carbon tetrachloride should be handled in the laboratory using the "basic prudent
practices".
Shipping
UN1846 Carbon tetrachloride, Hazard Class:
6.1; Labels: 6.1-Poisonous materials.
Purification Methods
For many purposes, careful fractional distillation gives adequate purification. Carbon disulfide, if present, can be removed by shaking vigorously for several hours with saturated KOH, separating, and washing with water: this treatment is repeated. The CCl4 is shaken with conc H2SO4 until there is no further coloration, then washed with water, dried with CaCl2 or MgSO4 and distilled (from P2O5 if desired). It must not be dried with sodium. An initial refluxing with mercury for 2hours removes sulfides. Other purification steps include passage of dry CCl4 through activated alumina, and distillation from KMnO4. Carbonyl containing impurities can be removed by percolation through a Celite column impregnated with 2,4-dinitrophenylhydrazine (DNPH), H3PO4 and water. (Prepared by dissolving 0.5g DNPH in 6mL of 85% H3PO4 by grinding together, then mixing with 4mL of distilled water and 10g Celite.) [Schwartz & Parks Anal Chem 33 1396 1961]. Photochlorination of CCl4 has also been used: CCl4 to which a small amount of chlorine has been added is illuminated in a glass bottle (e.g. for 24hours with a 200W tungsten lamp near it), and, after washing out the excess chlorine with 0.02M Na2SO3, the CCl4 is washed with distilled water and distilled from P2O5. It can be dried by passing through 4A molecular sieves and distilled. Another purification procedure is to wash CCl4 with aqueous NaOH, then repeatedly with water and N2 gas is bubbled through the liquid for several hours. After drying over CaCl2 it is percolated through silica gel and distilled under dry N2 before use [Klassen & Ross J Phys Chem 91 3664 1987]. [Beilstein 1 IV 56.]
Toxicity evaluation
Most of the carbon tetrachloride produced is released to the
atmosphere. In the atmosphere, photodegradation by shorter
wavelength ultraviolet radiation appears to be the primary
removal process although it is very stable in the environment
remaining in the air for several years before breaking down, so
a significant global transport is expected. The estimated half-life
of atmospheric carbon tetrachloride is 30–100 years. Small
amounts can be released to the water but due to the relatively
high rate of volatilization from water, carbon tetrachloride
tends to evaporate in a short time. It is stable to hydrolysis in
water. Most of the amount released to soil evaporates rapidly
due to its high vapor pressure but a small proportion could
remain associated to the soil organic matter. Carbon tetrachloride
is mobile in most soils depending on the organic
carbon content and can reach groundwater where it remains for
long periods before it is broken down to other chemicals.
Incompatibilities
Oxidative decomposition on contact with
hot surfaces, flames, or welding arcs. Carbon tetrachloride
decomposes forming toxic phosgene fumes and hydrogen
chloride. Decomposes violently (producing heat) on contact
with chemically active metals, such as aluminum, barium,
magnesium, potassium, sodium, fluorine gas, allyl alcohol,
and other substances, causing fire and explosion hazard.
Attacks copper, lead, and zinc. Attacks some coatings, plastics, and rubber. Becomes corrosive when in contact with
water; corrosive to metals in the presence of moisture.
Waste Disposal
Incineration, preferably after
mixing with another combustible fuel; care must be exercised to assure complete combustion to prevent the formation of phosgene; an acid scrubber is necessary to remove
the halo acids produced. Recover and purify by distillation where possible.
Check Digit Verification of cas no
The CAS Registry Mumber 56-23-5 includes 5 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 2 digits, 5 and 6 respectively; the second part has 2 digits, 2 and 3 respectively.
Calculate Digit Verification of CAS Registry Number 56-23:
(4*5)+(3*6)+(2*2)+(1*3)=45
45 % 10 = 5
So 56-23-5 is a valid CAS Registry Number.
InChI:InChI=1/CCl4/c2-1(3,4)5
56-23-5Relevant articles and documents
Dismutation of CFC-12 to CFC-13 over Chromia-Alumina Catalyst
Venugopal, A.,Rao, K. S. Rama,Prased, P. S. Sai,Rao, P. Kanta
, p. 2377 - 2378 (1995)
Selective transformation of CCl2F2 (CFC-12) to fluorine-rich CClF3 (CFC-13) in the absence of HF over a chromia-alumina catalyst has been achieved.
Photocatalysis of Chloroform Decomposition by Tetrachlorocuprate (II) on Dowex 2-X8
Harvey, Brent M.,Hoggard, Patrick E.
, p. 1234 - 1242 (2014)
Heterogenized on a polystyrene anion exchange resin and in the presence of oxygen, CuCl24 catalyzes the photodecomposition of chloroform at wavelengths above 345 nm with greater efficiency than an equivalent amount in homogeneous solution. The reaction is proposed to proceed in two stages, the first stage yielding CCl4 and HO2 as products, the second consisting of a chain reaction resulting from the CuCl2 4-catalyzed photodissociation of CCl4, yielding phosgene with CCl3 radicals as chain carriers. Photodecomposition is retarded by added Cl, CH3CN, C6H12 or C2H5OH, which is ascribed to the displacement of CHCl3 molecules from the vicinity of the copper by attraction to the polystyrene matrix or to the alkylammonium cation sites.
Kinetics and mechanism of the thermal chlorination of chloroform in the gas phase
Huybrechts,Hubin,Van Mele
, p. 466 - 472 (2000)
The gas-phase thermal chlorination of CHCl3 has been studied up to high conversions by photometry and gas chromatography in a conditioned static quartz reaction vessel between 573 and 635 K. The initial pressures of both CHCl3 and Cl2 ranged from about 10-100 Torr, and the initial total pressure was varied between about 30-190 Torr. The reaction is rather complex because the produced CCl4 is not stable. The rate of consumption of Cl2 therefore increases in the course of time. This acceleration is explained quantitatively in terms of a radical mechanism and its kinetic and thermodynamic parameters. This reaction model is based on a known model for the pyrolysis of CCl4 to which only one reaction couple involving CHCl3 has been added. Analyses of the rates of the homogeneous elementary steps show that the primary source of Cl atoms is the second-order dissociation of Cl2, which is rapidly superseded by a secondary source, the first-order dissociation of the CCl4 primary product.
A new strategy to improve catalytic activity for chlorinated volatile organic compounds oxidation over cobalt oxide: Introduction of strontium carbonate
Liu, Hao,Shen, Kai,Zhao, Hailin,Jiang, Yongjun,Guo, Yanglong,Guo, Yun,Wang, Li,Zhan, Wangcheng
, (2021)
Co3O4–SrCO3 catalysts with various Sr/Co ratios were synthesized by the coprecipitation method, and their properties were tuned by adjusting the Sr/Co molar ratio. Furthermore, the catalytic combustion of vinyl chloride (VC) was used to evaluate the catalytic activity of the Co3O4–SrCO3 catalysts. The physicochemical properties of the catalysts were studied by X-ray diffraction (XRD), infrared spectroscopy (IR), N2 sorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR) and VC temperature-programmed desorption (VC-TPD). The results showed that the Co3O4–SrCO3 catalysts exhibited composite phases of Co3O4 and SrCO3 and the presence of interactions between them. As a result, the crystallization of the Co3O4 phase for the Co3O4–SrCO3 catalysts was restrained, and the state of Co on the catalyst surface was adjusted. Furthermore, the reducibility and VC adsorption capacity of the Co3O4–SrCO3 catalysts with Sr/Co molar ratios of 0.2 and 0.4 were enhanced compared with those of the Co3O4 catalyst. Otherwise, catalyst SrCo-0.4 exhibited excellent catalytic performance, accompanied by the highest reaction rate and the lowest apparent activation energy. More importantly, the optimized SrCO3–Co3O4 catalyst showed superior catalytic performance compared with other transition metal oxides in previous literature. These results brought a new idea for promoting the activity of transition metal catalysts for the deep oxidation of chlorinated volatile organic compounds (CVOCs) by introducing alkaline-earth metal salts.
Total Oxidation of Chlorinated Hydrocarbons by Copper and Chlorine based Catalysts
Green, Malcolm L. H.,Lago, Rochel M.,Tsang, Shik Chi
, p. 365 - 366 (1995)
A new class of combustion catalyst containing copper and chlorine is described which has high activity for the total oxidation of chlorinated hydrocarbons such as CH2Cl2, CH2ClCH2Cl, CCl4 and 1,2-dichlorobenzene (1percent of gas stream) into carbon oxides, HCl and Cl2, in the presence of excess air at 300-500 deg C; no catalyst deactivation or loss of copper or chlorine is observed.
The laser two-photon photolysis of liquid carbon tetrachloride
Zhang,Thomas
, p. 158 - 162 (2006)
The two-photon photolysis of liquid CCl4 with 25 ps pulses of 266 nm light has been studied and compared with similar studies with high energy radiation. Both neutral and ionic species are produced from excited states and ionization. The emphasis of the study is on the ionic processes, while some data related to excited states and free radicals are presented. In both radiolysis and photolysis, a solvent separated charged pair, CCl3+ ∥ Cl-, exhibiting a λmax at 475 nm, is observed that exhibits a total growth over 38 to 100 ps. Solutes with ionization potentials less than that of CCl4 (11.47 eV) reduce the yield of the 475 nm species producing radical cations of the solute. The efficiency of this process is about 10-fold larger in radiolysis compared with photolysis. Analysis of the data suggest that the lower energy of two-photon photolysis produces a charge pair CCl4+ ∥ CCl4-, which decays in about 3 ps to CCl4+ ∥ Cl-. This species then decays to CCl3+ ∥ Cl-. The lifetime of the growth of the 475 nm is measured as 46 ps. These studies clearly show areas where radiolysis and photolysis can be quite similar and also areas where the vast difference in excitation energy introduces stark differences in the observed radiation and photoinduced chemistry.
Onion-Like Graphene Carbon Nanospheres as Stable Catalysts for Carbon Monoxide and Methane Chlorination
Centi, Gabriele,Barbera, Katia,Perathoner, Siglinda,Gupta, Navneet K.,Ember, Erika E.,Lercher, Johannes A.
, p. 3036 - 3046 (2015)
Thermal treatment induces a modification in the nanostructure of carbon nanospheres that generates ordered hemi-fullerene-type graphene shells arranged in a concentric onion-type structure. The catalytic reactivity of these structures is studied in comparison with that of the parent carbon material. The change in the surface reactivity induced by the transformation of the nanostructure, characterized by TEM, XRD, X-ray photoelectron spectroscopy (XPS), Raman, and porosity measurements, is investigated by multipulses of Cl2 in inert gas or in the presence of CH4 or CO. The strained C-C bonds (sp2-type) in the hemi-fullerene-type graphene shells induce unusually strong, but reversible, chemisorption of Cl2 in molecular form. The active species in CH4 and CO chlorination is probably in the radical-like form. Highly strained C-C bonds in the parent carbon materials react irreversibly with Cl2, inhibiting further reaction with CO. In addition, the higher presence of sp3-type defect sites promotes the formation of HCl with deactivation of the reactive C-C sites. The nano-ordering of the hemi-fullerene-type graphene thus reduces the presence of defects and transforms strained C-C bonds, resulting in irreversible chemisorption of Cl2 to catalytic sites able to perform selective chlorination. Tidy up the carbon! CO and CH4 chlorination over hemi-fullerene-type graphene is described. The surface nano-ordering, induced by thermal treatment, transforms strained C-C bond sites resulting in irreversible Cl2 chemisorption to catalytic sites that are able to selectively chlorinate CO and CH4.
Kinetics of the R + Cl2 (R = CH2Cl, CHBrCl, CCl3 and CH3CCl2) reactions. An ab initio study of the transition states
Seetula, Jorma A.
, p. 3561 - 3567 (1998)
The kinetics of the reactions of CH2Cl, CHBrCl, CCl3 and CH3CCl2 radicals with molecular chlorine were investigated in a heatable tubular reactor coupled to a photoionization mass spectrometer. The reactions were studied under pseudo-first-order conditions. The radicals were photogenerated at 248 nm. The pressure-independent rate constants determined were fitted to the following Kooij and Arrhenius expressions (units in cm3 molecule-1 s-1): k-(CH2Cl) = 7.56 × 10-17(T)1.45 exp(-350 J mol-1/RT), k(CHBrCl) = 5.83 × 10-20(T)2.3 exp(-300 J mol-1/RT), k(CCl3) = (8.4 ± 2.9) × 10-13 exp[-(25 ± 9) kJ mol-1/RT] and k(CH3CCl2) = 1.10 × 10-26(T)4.3 exp(+15000 J mol-1/RT). The Arrhenius rate expression for the Cl + CCl4 reaction was determined to be k(Cl + CCl4) = (3.9 ± 3.2) × 10-13 exp[-(71 ± 9) kJ mol-1/RT] using the kinetics measured and the thermochemistry of the CCl3 radical. Errors for the Kooij expressions were estimated to be 25% overall, and for the Arrhenius expressions they were calculated to be 1σ + Student's t values. The transition states of the measured R + Cl2 and four other similar reactions were localized and fully optimized at the MP2/6-31G(d,p) level of theory by ab initio methods. The energetics of the reactions were considered by determining thermochemical and activation parameters of the reactions. The reactivity differences of the radicals studied were explained by a free-energy correlation using an electronegativity difference scale.
Aluminium(III) Chloride-Chlorohydrocarbon Chemistry. Fourier Transform Infra-red Spectroscopic Studies of the Reactions between Solid Aluminium(III) Chloride and 1,1,1-Trichloroethane or 1,1-Dichloroethene Vapours
McBeth, David G.,Winfield, John M.,Cook, Bernard W.,Winterton, Neil
, p. 671 - 676 (1990)
The reactions of 1,1,1-trichloroethane and 1,1-dichloroethene vapours with solid aluminium(III) chloride have been studied using Fourier-transform i.r. spectroscopy to determine stoicheiometries as a function of time.Dehydrochlorination of 1,1,1-trichloroethane to give 1,1-dichloroethene and hydrogen chloride appears to be the only important process in the initial stage of the reaction, but the 1,1-dichloroethene formed reacts with the solid phase and the main product is a mixture of involatile chlorohydrocarbon species.The quantity of hydrogen chloride evolved indicates that the involatile material is highly unsaturated and in both reactions AlCl3 becomes progressively coated with a strongly purple-coloured tar.Small quantities of carbon tetrachloride are also produced in both reactions.
PRODUCTION OF CARBON TETRACHLORIDE FROM NATURAL GAS
-
Paragraph 0058, (2020/07/07)
The present invention provides processes to prepare carbon tetrachloride by the chlorination of natural gas in the presence of a diluent.
