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|Trichloroethylene Chemical Properties|
|Melting point ||-86 °C|
|Boiling point ||87 °C|
|density ||1.463 g/mL at 25 °C(lit.)|
|vapor density ||4.5 (vs air)|
|vapor pressure ||61 mm Hg ( 20 °C)|
|refractive index ||n20/D 1.476(lit.)|
|storage temp. ||0-6°C
|Water Solubility ||Slightly soluble. 0.11 g/100 mL|
|Stability:||Stable. Incompatible with oxidizing agents, aluminium, magnesium, strong bases, reducing agents. Light-sensitive. Reacts violently with many metals, ozone, potassium nitrate, potassium hydroxide, sodium hydroxide.|
|CAS DataBase Reference||79-01-6(CAS DataBase Reference)|
|NIST Chemistry Reference||Trichloroethylene(79-01-6)|
|EPA Substance Registry System||Ethene, trichloro-(79-01-6)|
|Trichloroethylene Usage And Synthesis|
|Outline||Trichloroethylene (TCE), also known as acetylide trichloride, is a colorless, volatile liquid solvent with strong ability of dissolving. It is insoluble in water and soluble in alcohol, ether and other organic solvents. It is non-combustible under normal conditions. Because of its moderate boiling point, high vapor pressure and high stability as well as being suitable for the air wash operation in the industry for metal cleaning (for complete degreasing) as well as removal of fat and fiber. With its strong feature for dissolution, it is commonly used for removing dirt which is difficult to remove such as semi-hardened varnish, coating sectional agent, thicker flux; it can also be used as extracting agent, solvent and low-temperature HTF media. As the raw material of intermediate, it can be used for the production of tetrachlorethylene, acid, dichloroacetic chloride, octachlorodipropylether, HCFC-123, HCFC-124, HFC-125, HFC-134a and the like.
|Physical and Chemical Properties||It is colorless oily liquid with smells being similar as chloroform. It is volatile with the relative molecular mass of 131.29, the relative density of 1.4642, melting point of-73 ℃, and boiling point of 86.7 ℃. It has a flash point of 32.2 ℃, the refractive index of 1.4773, and the viscosity of 0.58mPa • s (20 ℃). The critical temperature is 271 ℃. Critical pressure is 5.02MPa. It is slightly soluble in water (0.107 at 20 ℃ while 0.124 at 60 ℃), soluble in alcohol, ether, acetone and chloroform, and soluble in a variety of fixed oil and volatile oil. At wet condition, it can generate hydrochloric acid upon exposure to light. High concentrations of vapor will burn at high temperatures. It will be decomposed upon heating and emit toxic chloride. Upon being heated to 250~600 ℃, it can generate phosgene upon contact with iron, copper, zinc, and aluminum. It can have fierce reaction with barium, nitrogen tetroxide, lithium, magnesium, liquid oxygen, ozone, potassium hydroxide, potassium nitrate, sodium hydroxide, and titanium. This product is however less stable and easily to be oxidized, generating dichloroacetyl chloride or phosgene, carbon monoxide and hydrochloric acid. It can undergo further chlorination, generating pentachloroethane or perchlorethylene. It can be brominated or fluorinated upon the action of the catalyst. It can undergo either self-polymerization, also co-polymerized with vinyl chloride, vinyl acetate, propylene, butene, butadiene and acrylonitrile. This vapor of this product can form explosive mixture with air with the explosion limit being 8.0%~10.5% (volume fraction).
|Preparation||Currently, the major production methods of trichlorethylene include acetylene, direct chlorination of ethylene, and ethylene oxy-chlorination method. According to information, trichlorethylene can also be produced using vinyl chlorination upon heating, and the joint process between cold chlorination and oxy-chlorination while generating several products including vinyl chloride, dichloroethylene, trichlorethylene, tetrachloroethane, dichloroethane, etc. It enables the rational application of resources as well as the reduction of byproducts. In addition, trichlorethylene can also made from tetrachlorethylene which undergoes dehydrochlorination under vapor phase. This method can eliminate the emission of saponification residue and thereby greatly reducing the contamination of organochlorine of the environment with producing by-product of hydrochloric acid. |
Use anhydrous ferric chloride as a catalyst under reduced pressure, have addition reaction between acetylene and chlorine for generating tetrachloroethane, which is further reacted with lime to produce calcium chloride and trichlorethylene. The generated trichlorethylene and water were co-boiled and distilled off with both low-boiling substance and high-boiling substance being subsequently removed via low-boiling and high-boiling distillation column, respectively to obtain the finished product of trichlorethylene. The saponification process is simple, but yielding a large number of saponification residue, each producing 1t trichlorethylene product will produce 5~8t saponification residue, greater pressure on environmental protection, and therefore the new domestic unit trichlorethylene has no saponification French technology to produce trichlorethylene products. The reaction equation is as follows:
Figure 1 is a schematic view of saponification process
(2) Gas-phase catalytic dehydrochlorination method
The current novel domestic plant for production of trichlorethylene applies vapor phase dehydrochlorination process. This method is through the vaporization of tetrachloroethane, under the condition of 200~290 ℃, tetrachloroethane gas enters into the fixed bed reactor containing the catalyst. Then tetrachloroethane generate crude trichlorethylene after dehydrochlorination with a few amount of pentachlorocyclohexane also being transformed into tetrachlorethylene. After the dehydrochlorination reaction, the finished trichlorethylene is obtained through the multi-column separation. The reaction equation is as follows:
C2H2 + 2Cl2 → CHCl2CHCl2
CHCl2CHCl2 + Cl2 → CHCl2CCl3 + HCl
CHCl2CHCl2 → CHCl = CCl2 + HCl
CHCl2CCl3 → CCl2 = CCl2 + HCl
2. The direct chlorination of ethylene
Direct chlorination of ethylene is through putting ethylene and chlorine gas for reaction in dichloroethane solution with the ferric chloride as catalyst to generate 1,2-dichloroethane which undergoes further chlorination to generate the mixture of trichlorethylene and tetrachlorethylene with the reaction undergoing at high temperature of 280~450 ℃; Then further go through distillation, ammonia neutralization, washing, and drying to obtain the trichlorethylene and tetrachlorethylene products, respectively. The reaction equation is as follows:
Figure 2 is a schematic diagram of an ethylene chlorination process
3. Ethylene oxy-chlorination
Ethylene oxy-chlorination is through addition reaction between ethylene and chlorine into 1, 2-dichloroethane, and then further have oxy-chlorination with chlorine and oxygen with supplying the catalyst with at the temperature of 425 °C. The product is cooled, washed with water, dried and distilled, isolated to obtain trichlorethylene and tetrachlorethylene. The reaction equation is as follows:
C2H2 + Cl2 → ClCH2CH2Cl
8ClCH2CH2Cl + 6Cl2 + 7O2 → 4ClCH = CCl2 + 4CCl2 = CCl2 + 14H2O
The above information is edited by the Chemicalbook of Dai Xiongfeng.
|Precautions||Because of the toxicity of this product, we should note the following tips; the clinical manifestations of poisoning: |
1. Acute poisoning: headache, dizziness, nausea, vomiting, unsteady gait like drunkenness with difficulty in breathing in severe cases, delirium, delirium, convulsions, seizures, as well as quick appearance of inhibition of the respiratory center or circulatory failure as well as combined liver and kidney damage. Upon fire, trichlorethylene can produce phosgene to cause pulmonary edema. During the acute recovery period, it can appear that mental depression, paranoid psychosis, peripheral nerve classes and optic neuritis, optic atrophy and blindness. It will occasionally cause sudden death due to overwork.
2. Chronic poisoning: fatigue, weakness, loss of work ability, headaches, episodes of dizziness, irritability, sleep disturbance, loss of appetite, gastrointestinal disorders, chest tightness, palpitations, angina-like pain, peripheral neuropathy, autonomic dysfunction and liver damage. Long-term exposure to trichlorethylene can cause addiction and reduced alcohol tolerance.
3. TCE exposure can cause dermatitis, eczema, or bulla, and conjunctival and corneal damage. Because of its role of degreasing, it can easily cause dry skin and secondary infections.
There is no specific antidote with can be treated with general aid measures and symptomatic treatment. Make sure for protecting the liver, kidney and avoid using epinephrine; stop drinking.
You can take the following precautions to avoid poisoning:
1. Strengthen the ventilation equipment of production device.
2. It can be used for metal degreasing and cleaning metal device.
3. Pay attention to personal protection, avoid direct skin contact with trichlorethylene, and wear rubber gloves when necessary.
4. Check before work; for patients with disease in nervous system, respiratory, circulatory system should not engage in the work of trichlorethylene.
|Uses||1. Cleaner |
As a cleaning agent, it has a rapid development in the market of the cleaning of metal parts and electronic components market, mainly used in the various kinds of fields including color TV sets, refrigerators, cars, air conditioners, precision machinery and microelectronics industries for being used for cleaning metal parts and electronic components.
2. Chemical Intermediates
It is currently used for the consumption of chemical intermediate areas. The domestic industrialized downstream products of trichlorethylene include tetrachlorethylene, hexachloroethane, dichloroacetyl chloride, octachlorodipropylether, HFC-134a, etc. It is mainly driven by the production of HFC-134a. Owing to the rapid industrialization of domestic production of HFC-134a, the ratio of trichlorethylene in the consumption structure as chemical intermediates has increased substantially.
As the solvent, extracting agent, its consumption is about 15% of total consumption, mainly used for the production of caprolactam, pesticides and pharmaceuticals. Pesticides with trichlorethylene as the solvent include trichlorfon and dimethoate which are popular pesticides in China. The application of trichloroethylene being used as the extractant agent for purification of the pharmaceutical intermediates-methoxy-phthalic acid has also increased largely in recent years.Application of trichlorethylene in other areas of consumption includes expanding agent, coating of unsaturated resin, which accounts for 5%; application of PCE and refrigeration agents accounts about 10%.
|Toxicity||FAO/WHO (2001): ADI not specified (use the lowest amount of process as limitation). |
LD50: 3670mg/kg (rat, oral).
|Chemical Properties||It is colorless, stable heavy oily liquid with low-boiling point and chloroform-like odor. It is generally miscible with organic solvent and slight soluble in water.
|Acute toxicity||Oral-rat LD50: 5650 mg/kg; Oral-Mouse LD50: 2402 mg/kg
|Irritation data||Skin-Rabbit 2 mg/24 hours, severe; Eyes-rabbit 20 mg/24 hours, moderate.
|Hazardous characteristics of explosive||it can be explosive when mixed with air
|Flammability hazard characteristics||it is combustible in case of fire and heat combustible with combustion releasing toxic chloride
|Storage characteristics||Treasury: ventilation, low-temperature and drying; store it separately from food additives.
|Chemical Properties||colourless liquid|
|Extinguishing agent||Water spray, foam, CO2, sand
|Definition||ChEBI: A member of the class of chloroethenes that is ethene substituted by chloro groups at positions 1, 1 and 2.|
|Professional standards||TWA 270 mg/m³; STEL 405 mg/m3|
|General Description||A clear colorless volatile liquid having a chloroform-like odor. Denser than water and is slightly soluble in water. Noncombustible. Used as a solvent, fumigant, in the manufacture of other chemicals, and for many other uses.|
|Air & Water Reactions||Slightly soluble in water.|
|Reactivity Profile||Trichloroethylene has been determined experimentally that mixtures of finely divided barium metal and a number of halogenated hydrocarbons possess an explosive capability. Specifically, impact sensitivity tests have shown that granular barium in contact with monofluorotrichloromethane, trichlorotrifluoroethane, carbon tetrachloride, Trichloroethylene, or tetrachloroethylene can detonate (ASESB Pot. Incid. 39. 1968; Chem. Eng. News 46(9):38. 1968). Trichloroethylene has been determined experimentally that a mixture of beryllium powder with carbon tetrachloride or with Trichloroethylene will flash or spark on heavy impact (ASESB Pot. Incid. 39. 1968). A mixture of powdered magnesium with Trichloroethylene or with carbon tetrachloride will flash or spark under heavy impact (ASESB Pot. Incid, 39. 1968).|
|Health Hazard||INHALATION: symptoms range from irritation of the nose and throat to nausea, an attitude of irresponsibility, blurred vision, and finally disturbance of central nervous system resulting in cardiac failure. Chronic exposure may cause organic injury. INGESTION: symptoms similar to inhalation. SKIN: defatting action can cause dermatitis. EYES: slightly irritating sensation and lachrymation.|
|Fire Hazard||Special Hazards of Combustion Products: Toxic and irritating gases are produced in fire situations.|
|Trichloroethylene Preparation Products And Raw materials|
|Raw materials||Chlorine-->Carbon tetrachloride-->Ferric chloride-->Calcium carbide-->LACQUER THINNER-->Tetrachloroethylene-->1,1,2,2-Tetrachloroethane-->1,1,2,2-TETRACHLOROETHANE-D2-->PENTACHLOROETHANE|
|Preparation Products||Chloroacetic acid-->Cleaning agent-->Hexamethylphosphoramide-->Dimethoate-->Tetrachlorvinphos-->Tetrachloroethylene-->Dichlorvos-->Hexachloroethane-->Ethlenethiourea-->2-Phenylphenol-->Dichloroacetyl chloride-->CAPSANTHIN-->Pentoxyverine-->Bithionol-->CHLOROPHYLL A-->4-Phenylphenol-->4-Amino-6-methoxypyrimidine-->3-AMINO-4,5,6,7-TETRAHYDRO-BENZO[B]THIOPHENE-2-CARBOXYLIC ACID METHYL ESTER-->TETRACHLOROCYCLOPROPENE-->chlorophyllin copper complex sodium salt-->Bis(2,3,3,3-tetrachloropropyl) ether-->PENTACHLOROETHANE-->DIPROPETRYN-->1,1,1-Trichlorotrifluoroethane-->Sodium 2-biphenylate-->Simazine-->4-ISOPROPYL-3-METHYLPHENOL-->Sulfamonomethoxine-->2,4,6-TRIFLUOROPHENYL ISOTHIOCYANATE-->Sulfadimethoxine sodium salt |