What is 79-34-5 and Why Do We Use Them?

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[General Description]

Colorless to pale yellow liquid with a sweet odor. Sinks in water.[Reactivity Profile]

1,1,2,2-TETRACHLOROETHANE(79-34-5) may be incompatible with strong oxidizing and reducing agents. Also may be incompatible with many amines, nitrides, azo/diazo compounds, alkali metals, and epoxides. Decomposed by heat and UV light, forming phosgene and HCl; reacts violently with finely dispersed metals [Handling Chemicals Safely . p. 886].[Air & Water Reactions]

Insoluble in water.[Health Hazard]

Compound is a powerful narcotic and liver poison; may also cause changes in blood composition and neurological disturbances. Repeated exposure by inhalation can be fatal. Ingestion causes vomiting, diarrhea, severe mucosal injury, liver necrosis, cyanosis, unconsciousness, loss of reflexes, and death. Contact with eyes causes irritation and lachrymation. Can be absorbed through the skin and may produce severe skin lesions.[Potential Exposure]

Tetrachloroethane is used as an intermediate in the trichloroethylene production from acetylene and as a solvent; as a dry cleaning agent; as a fumigant; in cement; and in lacquers. It is used in the manufacture of artificial silk, artificial leather, and artificial pearls. Recently, its use as a solvent has declined due to replacement by less toxic compounds. It is also used in the estimation of water content in tobacco and many drugs, and as a solvent for chromium chloride impregnation of furs.[Fire Hazard]

Special Hazards of Combustion Products: Irritating hydrogen chloride vapor may form in fire.[First aid]

If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.[Shipping]

UN Tetrachloroethane or 1,1,2,2Tetrachloroe thane, Hazard Class: 6.1; Labels: 6.1Poisonous materials.[Incompatibilities]

Violent reaction with chemically active metals; strong caustics; strong acids; especially fuming sulfuric acid. Degrades slowly when exposed to air. Attacks plastic and rubber.[Chemical Properties]

colourless to light yellow liquid with a chloroform-like[Chemical Properties]

Tetrachloroethane is a heavy, volatile colorless to light yellow liquid. It has a sweetish, chloroform-like odor. The Odor Threshold is 0.5 ppm in water and 1.5 ppm in air.[Waste Disposal]

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (&#;100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and 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.[Physical properties]

Colorless to pale yellow liquid with a sweet, chloroform-like odor. A detection odor threshold concentration of 50 mg/m3 (7.3 ppmv) was experimentally determined by Dravnieks ().[Uses]

1,1,2,2-Tetrachloroethane, once used as a solvent for cleaning and extraction processes, is still used to some extent as a chemical intermediate. Present usage is quite limited because less toxic solvents are available.[Uses]

Intermediate in the production of trichloroethylene, tetrachloroethylene, and 1,2-dichloroethylene; previously used as a solvent, insecticide and fumigant.[Uses]

Nonflammable solvent for fats, oils, waxes, resins, cellulose acetate, rubber, copal, phosphorus, sulfur. As solvent in certain types of Friedel-Crafts reactions or phthalic anhydride condensations. In the manufacture of paint, varnish, and rust removers. In soil sterilization and weed killer and insecticide formulations. In the determination of theobromine in cacao. As immersion fluid in crystallography. In the biological laboratory to produce pathological changes in gastrointestinal tract, liver, and kidneys. Intermediate in the manufacture of trichloroethylene and other chlorinated hydrocarbons having two carbon atoms.[Definition]

ChEBI: A member of the class of chloroethanes that is ethane substituted by chloro groups at positions 1, 1, 2 and 2.[Hazard]

Toxic by ingestion, inhalation, skin absorption. Questionable carcinogen.[Carcinogenicity]

The EPA has classified this material as &#;likely to be carcinogenic to humans&#; based on data from an oral cancer bioassay in male and female Osborne&#;Mendel rats and B6C3F1 mice. In mice, a significant increase in the incidence of hepatoceullar carcinomas in both genders was observed. Male Osborne&#;Mendel rats showed increased incidence of hepatocellular carcinomas, which is a rare tumor in this strain.
The National Cancer Institute has included 1,1,2,2- tetrachloroethane in their bioassay series using rats and mice. Their summary states that the time-weighted average doses (by gavage) were 108 and 62 mg/kg/day for male rats, 76 and 43 mg/kg/day for female rats, and 282 and 142 mg/kg/day for all mice. There was a highly significant positive dose-related trend in the incidence of hepatocellular carcinoma in mice of both sexes. No statistically significant incidence of neoplastic lesions was observed in male or female rats. However, two hepatocellular carcinomas and one neoplastic nodule, which are rare tumors in the male Osborne&#;Mendel rat, were observed in high-dose males. Under the conditions of this bioassay, orally administered 1,1,2,2-tetrachloroethane was a liver carcinogen in B6C3Fl mice of both sexes.
The proposed metabolic pathway involves the production of dichloroacetic acid, which was identified as the major urinary metabolite in treated mice. Other pathways involve formation of trichloroethylene via dehydrochlorination or tetrachloroethylene via oxidation. Free radicals may also be formed.
From the NCI study, a oral slope factor (OSF) of 0.2 per mg/kg/day was developed by the EPA. No inhalation unit risk (IUR) was determined by the EPA because of absence of data from inhalation exposure.[Environmental Fate]

Biological. Monodechlorination by microbes under laboratory conditions produced 1,1,2- trichloroethane (Smith and Dragun, ). In a static-culture-flask screening test, 1,1,2,2- tetrachloroethane (5 and 10 mg/L) was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum. No significant degradation was observed after 28 d of incubation (Tabak et al., ).
Chemical/Physical. In an aqueous solution containing 0.100 M phosphate-buffered distilled water, 1,1,2,2-tetrachloroethane was abiotically transformed to 1,1,2-trichloroethane. This reaction was investigated within a temperature range of 30 to 95 °C at various pHs (5 to 9) (Cooper et al., ). Abiotic dehydrohalogenation of 1,1,2,2-tetrachloroethane yielded trichloroethylene (Vogel et al., ) and HCl (Kollig, ). The half-life for this reaction at 20 °C was reported to be 0.8 yr (Vogel et al., ). Under alkaline conditions, 1,1,2,2-tetrachloroethane dehydrohalogenated to trichloroethylene. The reported hydrolysis half-life of 1,1,2,2-tetrachloroethane in water at 25 °C and pH 7 is 146 d (Jeffers et al., ).
The evaporation half-life of 1,1,2,2-tetrachloroethane (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 was 55.2 min (Dilling, ).
At influent concentrations of 1.0, 0.1, 0.01, and 0.001 mg/L, the GAC adsorption capacities were 11, 4.5, 1.9, and 0.8 mg/g, respectively (Dobbs and Cohen, ).[Purification Methods]

Stir the ethane, on a steam-bath, with conc H2SO4 until a fresh portion of acid remains colourless. The organic phase is then separated, distilled in steam, dried (CaCl2 or K2CO3), and fractionally distilled in a vacuum. [Beilstein 1 IV 144.][Toxicity evaluation]

Metabolism of tetrachloroethane to reactive products plays a key role in its toxicity. Both nuclear and microsomal cytochrome P450 enzymes have been implicated in the metabolism of the compound, possibly releasing aldehydes, alkenes, acids, and free radicals that may react with biological tissues. Therefore, because of high metabolic activity of the liver, the formation of active metabolites is a likely mechanism for the toxicity tetrachloroethane. Hence, tetrachloroethane metabolism could result in the reductive formation of radical products, leading to the stimulation of lipid peroxidation resulting in hepatotoxic effects, as noted in carbon tetrachloride, a structurally related chlorinated alkane. Both dichloroacetic and trichloroacetic acids are known to cause proliferation of peroxisomes.
The mechanism of neurological toxicity of tetrachloroethane has not been well characterized. Studies of similar compounds suggest that the parent compound itself may be the causative agent. This property allows interference with neural membrane function, bringing about central nervous system depression, behavioral changes, and anesthesia.
The mechanisms by which tetrachloroethane produces carcinogenic effects are incompletely characterized. Tetrachloroethane has been shown to bind to DNA in the liver and several other organs in rats and mice, which may contribute to the carcinogenic process. Studies indicate that there may be initiating and promoting activities when tetrachloroethane is metabolized, possibly by cytochrome P450 enzymes producing urinary metabolites such as dichloroacetic acid, trichloroacetic acid, trichloroethylene, and tetrachloroethylene. Studies of chronic exposure of rats and mice to these specific metabolites revealed hepatic tumors in male and female mice. Although it is possible that the carcinogenicity of tetrachloroethane involves metabolism with these compounds, there is no direct evidence linking one or more metabolites to its carcinogenic effects. Tetrachloroethane may be metabolized to form free radicals, which can in turn covalently bind to tissues, including DNA.