1,1,2,2-Тетрахлорэтан

Описание

1,1,2,2-Tetrachloroethane (tetrachloroethane) is a volatile, synthetic, colorless to pale-yellow dense liquid with a pungent, chloroform-like odor that is soluble in water and most organic solvents. There are no known natural sources of tetrachloroethane. Tetrachloroethane is a chemical intermediate in the production of a variety of other common chemicals. In the past, the major use for tetrachloroethane was in the production of trichloroethylene, tetrachloroethylene, and 1,2-dichloroethylene. With the development of new processes for manufacturing chlorinated ethylenes and the availability of less-toxic solvents, the production of tetrachloroethane as a commercial endproduct in the United States and Canada has steadily declined since the late 1960s and the production ceased by the early 1990s. Although at one time it was used as an insecticide, fumigant, and weed killer, it presently is not registered for any of these purposes. Its registration as an insect repellent was canceled by the Environmental Protection Agency (EPA) in the late 1970s.

Химические свойства

colourless to light yellow liquid with a chloroform-like

Физические свойства

Colorless to pale yellow liquid with a sweet, chloroform-like odor. A detection odor threshold concentration of 50 mg/m³ (7.3 ppm_v) was experimentally determined by Dravnieks (1974).

Использование

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.

Определение

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

Общее описание

Colorless to pale yellow liquid with a sweet odor. Sinks in water.

Реакции воздуха и воды

Insoluble in water.

Профиль реактивности

1,1,2,2-Tetrachloroethane 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 1980. p. 886].

Опасность

Toxic by ingestion, inhalation, skin absorption. Questionable carcinogen.

Угроза здоровью

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.

Пожароопасность

Special Hazards of Combustion Products: Irritating hydrogen chloride vapor may form in fire.

Возможный контакт

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.

Канцерогенность

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.

Перевозки

UN1702 Tetrachloroethane or 1,1,2,2Tetrachloroe thane, Hazard Class: 6.1; Labels: 6.1Poisonous materials.

Методы очистки

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.]

Несовместимости

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

Утилизация отходов

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.