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 is widely presented in the atmosphere, river water, sea water, seaweed and marine surface sediments. Its concentration in seawater is generally in ppb level. Carbon tetrachloride contained in red algae is estimated to be synthesized by the organism itself. The concentrations of carbon tetrachloride in the two hemispheres are very close, and are higher than the estimated amount based on production amount, which is related to the reaction of chlorine and methane in the atmosphere. Industrial produced carbon tetrachloride enters into the ocean mainly through the sea-air interface. It has been estimated that the atmospheric → ocean flux is 1.4 × 1010 g/year, being equivalent to 30% of the total carbon tetrachloride in the atmosphere. Carbon tetrachloride can be used as a tracer during the mixing of water masses.
At high temperature, carbon tetrachloride can react with metallic sodium and explodes, so that carbon tetrachloride can’t be used to extinguish the fire when metallic sodium is on fire.
The carbon tetrachloride may be prepared by treating carbon disulfide with dry chlorine in the presence of a catalyst.
1. Liver function tests: significant increase of serum ALT, AST activity can be used as the major diagnostic criteria of liver damage during the acute carbon tetrachloride poisoning. Serum heparin and serum prealbumin are also sensitive indicators. Upon severe damage, the serum bilirubin and prothrombin time was significantly increased, while serum albumin was significantly reduced.
2. Urine routine and renal function tests: changes in urine composition can be taken as the early evidence for indicating renal dysfunction. The increased blood urea nitrogen and creatinine, reduced creatinine clearance are commonly used and sensitive approaches for the determination of glomerular filtration rate (GFR). Patients with over 50% reduction in GFR may consider the diagnosis of acute renal failure.
3. Determination of carbon tetrachloride concentration in blood and expired gas can be used as a diagnostic reference.
Carbon tetrachloride, CC14, also known as tetrachloromethane, perchloro methane, and benzinoform, is a colorless liquid with a boiling point of 77 °C (170 OF). It is used as a solvent for lacquers, resin, and rubbers,and as a dry cleaning agent.
Dizziness, incoordination, anesthesia; may be accompanied by nausea and liver damage. Kidney damage also occurs, often producing decrease or stopping of urinary output.
Clinical manifestations of poisoning
The susceptibility of people to CCl4 toxicity varies greatly. After inhalation of high concentrations of CCl4 vapor, people can quickly appear coma, convulsions and other acute poisoning symptoms, together with pulmonary edema and respiratory paralysis. Inhalation of slightly higher concentration has effects of mental retardation, confusion, nausea, vomiting, abdominal pain and diarrhea. At 2 to 4 days after poisoning, people exhibit the signs of liver and kidney damage with ascites, acute liver necrosis and renal failure occurring in severe cases. In a few cases, people may also get myocardial damage, atrial fibrillation and ventricular premature beats. Oral poisoning can cause significant liver symptoms. Chronic poisoning is manifested as neurasthenia syndrome and gastrointestinal disorders with a few cases appearing hepatomegaly and abnormal liver function. Renal damage as well as optic neuritis and peripheral neuritis are very rare.
Hazards & Safety Information
Toxic grading poisoning
Acute toxicity Oral-Rat LD50: 2350 mg/kg; Oral-mouse LD50: 8263 mg/kg
Irritation Data Skin-Rabbit 500 mg/24 h Mild; Eyes-Rabbit 500 mg/24 h Mild
Flammable and hazardous characteristics it is non-combustible; in case of wet air and light, it is subject to decomposition into hydrochloric acid; it is decomposed upon high heating to release toxic chloride smoke
Storage and transportation characteristics Treasury: ventilated, low temperature and dry; store separately from food additives
Fire extinguishing agent itself is extinguishing agent
Occupational Standard TWA 13 mg/m3 STEL 25 mg/m3
Mainly apply symptomatic treatment on the nervous system and liver and kidney damage. For gastric lavage for treatment of oral poisoning, we can first use liquid paraffin or vegetable oil to dissolve poison, and prevent its inhalation into the respiratory tract. Avoid using epinephrine and alcohol-containing drugs, to prevent induced ventricular fibrillation and aggravation of the disease. Special attention should be paid to prevention and treatment of liver and kidney failure. Upon the occurrence of renal failure, we can use hemodialysis or peritoneal dialysis treatment.
A clear colorless liquid with a characteristic odor. Denser than water (13.2 lb / gal) and insoluble in water. Noncombustible. May cause illness by inhalation, skin absorption and/or ingestion. Used as a solvent, in the manufacture of other chemicals, as an agricultural fumigant, and for many other uses.
There are many approaches for production of carbon tetrachloride including methane thermal chlorination, carbon disulfide chlorination, and co-production of tetrachlorethylene, phosgene catalysis, methanone oxychlorination, high-pressure chlorination and methanol hydrochlorination. 1. Methane thermal chlorination: methane, when mixed with chlorine gas to have hot chlorination reaction in the 400-430 °C, generating crude product with by-product of hydrochloric acid. The crude product, after subjecting to neutralization, drying and distillation purification, can lead to the finished product. The fixed consumed amount of raw materials: natural gas (including methane 98%) 210 m3, liquid chlorine 2850 kg/t. 2. Carbon disulfide method: chlorine and carbon disulfide, with iron as the catalyst, are reacted at 90-100 °C; the reaction product is subject to fractionation, neutralization and distillation to obtain the finished product. This method needs less investment with the products easy to be purified. However, it demands high cost of equipment with serious corrosion of equipment. 3. Methanol oxygen chlorination: chlorine has a high utilization rate with no hydrogen chloride and waste halogenated hydrocarbon pollution. 4. High-pressure chlorination: avoid the generation of tetrachlorethylene. 5. Methanol hydrogenation and chlorination: the product is of good quality, resulting in high economic efficiency. In addition, dichloromethane and chloroform production can also co-produce tetrachloromethane.
Emergency treatment for leakage
Rapidly withdraw the personnel in the contaminated area to a safe area, and perform isolation, strict restrictions on access.
⑴ carbon tetrachloride appears as a colorless liquid; the approach for treatment of ground pollution accident emergency is the same as chloroform:
① Quickly build the soil, sand or other reachable materials into the dam to prevent the flow of liquid, in particular, prevent it from flowing into the nearby water; cover with soil and absorb it. It is also doable to dig a hole below its flow, collect it in a pit to prevent its further diffusion, and collect the liquid in a suitable container.
② do not use iron material (such as iron spoon, iron containers, shovels, etc.) during the process; Instead we should switch to other tools; because iron will help the decomposition of tetrachloromethane to produce more toxic phosgene. If possible, the operator should wear gas masks or other protective equipment during the process.
③ after the removal and stripping of the contaminated soil, collect them for treatment together; The following methods can be used based on the actual conditions:
A. Heat the soil and add water to make tetrachloromethane form into formic acid, carbon monoxide and hydrochloric acid;
B. Add concentrated alkali solution to the soil to make it react with tetrachloromethane to produce carbon monoxide;
C. Add dilute sodium hydroxide or potassium hydroxide into the soil to make it react with tetrachloromethane to form sodium formate or potassium formate;
The above operation should be avoided in the light conditions.
D. Incinerate the soil, ensuring complete combustion to prevent the generation of phosgene.
(2) As the carbon tetrachloride is very stable in the environment, some of the disposal technology of chloroform does not apply to it. It can only be applied of its volatile characteristics for natural or artificial mandatory volatilization to the atmosphere. When there is a large number of gaseous carbon tetrachloride getting evaporated and dispersed, population down the wind should be evacuated to prevent poisoning.
(3) Technology for the water pollution treatment is the same as that of chloroform: when tetrachloromethane enters into the water body, it should be try to block the channel between the contaminated waters and other waters with the method being building the dam to stop the flow; make a ditch to make it flow to another water body (such as sewage canal) and so on. Since tetrachloromethane is a kind of volatile halogenated hydrocarbon, the most simple and easy treatment method for the contaminated water body is the use of aeration (including deep aeration) method, so that it is quickly released from the water body to the atmosphere. In addition, several methods of treating the soil may be used as appropriate.
Waste disposal methods: Incineration. The waste is mixed with other fuels for burning; the combustion should be thoroughly in order to prevent the formation of phosgene. The hydrogen halide contained in the exhaust gas inside the incinerator is removed by an acid scrubber. In addition, consideration should be given to distillation and recovery of carbon tetrachloride.
Air & Water Reactions
Insoluble in water.
As solvent for oils, fats, lacquers, varnishes, rubber waxes, resins; starting material in manufacture of organic Compounds. Pharmaceutic aid (solvent). Formerly used as dry cleaning agent, fire extinguisher and grain fumigant.
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].
ChEBI: A chlorocarbon that is methane in which all the hydrogens have been replaced by chloro groups.
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 + 4HCl
Carbon 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 + 2HCl
In 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 + AgCl
In 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-& gt; CCl3F + HCl
CCl4 + 2HF-& gt; CCl2F2 + HCl
Carbon tetrachloride can react with sulfur at high temperatures (above 200 ° C) to produce carbon disulfide.
CCl4 + 6S → CS2 + 2S2Cl2
Under 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
||Manufacture of organic chlorine
||Chlorating agent or solvent
|Manucfacture of nylons
|Manufacture of rubber cement, soaps, insecticides, etc.
||Manufacture of chlorofluorocarbon propellants
||Be declining steadily for its detriment to the ozone layer
||Manufacture of chlorofluorocarbon refrigerants r-11 and r-12
||Carbon tetrachloride fire extinguisher
||Better for the fire of electrical appliance and precise instrument
||Dry cleaning fluid
||Non-polar structure，excellent dissolving ability for grease and oil
|Industrial de-greaser for metals
||Detection of boron, bromine, chlorine, molybdenum, tungsten and vanadium, phosphorus, silver
||Solvnt/no significant absorption bands > 1600 cm−1
|Proton NMR spectroscopy
||Solvent/no hydrogen atoms
||Reveal watermarks on postage stamps without damaging them
|Insects killing in grain
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.]
It appears as colorless transparent volatile liquid with a special aromatic odor. Sweet; 1 ml can be dissolved in 2000 ml water; it is also miscible with ethanol, ether, chloroform, benzene, carbon disulfide, petroleum ether and the majority of volatile oil.