Гексахлорбензол

Описание

Hexachlorobenzene is a white crystalline solid. This compound does not occur naturally. It is formed as a by-product during the manufacture of chemicals used as solvents (substances used to dissolve other substances), other chlorine-containing compounds, and pesticides. Small amounts of hexachlorobenzene can also be produced during combustion processes such as burning of city wastes. It may also be produced as a by-product in waste streams of chlor-alkali and wood-preserving plants. Hexachlorobenzene was widely used as a pesticide until 1965. It was also used to make fireworks, ammunition, and synthetic rubber.

Химические свойства

Hexachlorobenzene is a solid, crystallizing in nee dles.

Использование

Hexachlorobenzene is used as a fungicideand as an intermediate in organic synthesis.

Определение

hexachlorobenzene: A colourlesscrystalline compound, C₆Cl₆; m.p.227°C. It is made by the chlorinationof benzene with an iron(III) chloridecatalyst or by treating hexachlorocyclohexanewith chlorine in hexachloroethane.It is used to preservewood and dress seeds, and in themanufacture of hexafluorobenzene.

Общее описание

A white crystalline substance. Insoluble in water and denser than water. Contact may irritate skin, eyes and mucous membranes. May be toxic by ingestion. Used to make other chemicals.

Реакции воздуха и воды

HEXACHLOROBENZENE is sensitive to moisture. Insoluble in water.

Профиль реактивности

HEXACHLOROBENZENE reacts violently with dimethylformamide. .

Опасность

Possible carcinogen. Toxic by ingestion. Combustible.

Угроза здоровью

The acute oral and inhalation toxicity ofhexachlorobenzene is low in test animals.Repeated ingestion of this compound mayproduce porphyria hepatica (increased for mation and excretion of porphyrin) causedby disturbances in liver metabolism. The oralLD50 value in rabbits is 2600 mg/kg; theinhalation LC50 value from a single exposureis 1800 mg/m³ (NIOSH 1986). The occupa tional health hazard from inhalation shouldbe very low because of its very low vaporpressure (0.00001 torr).
Hexachlorobenzene causes cancer in ani mals. Oral administration of this compoundfor 18 weeks to 2 years caused tumors inthe liver, kidney, thyroid, and blood in rats,mice, and hamsters. It is a suspected humancarcinogen, evidence of which occurs to alimited extent.

Пожароопасность

Noncombustible solid; very low reactiv ity. Reaction with dimethyl formamide is reported to be violent at temperatures above 65°C (149°F) (NFPA 1997).

Возможный контакт

Hexachlorobenzene was used as a fun gicide; an additive for pyrotechnic compositions; and as wood preservative. It was used widely as a pesticide to pro tect seeds of onions and sorghum, wheat, and other grains against fungus until 1965. This material was used to make fireworks; ammunition for military uses; synthetic rubber; as a porosity controller in the manufacture of electrodes; as an intermediate in dye manufacture; in organic synthesis. It is formed as a by-product of making other chemicals; in the waste streams of chloralkali and wood-preserving plants; and when burning municipal waste. Currently, there are no commercial uses of hexachlorobenzene in the United States.

Канцерогенность

Hexachlorobenzene is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.

Метаболический путь

With the incubation of rat liver microsomes, hexachlorobenzene is metabolized to give pentachlorophenol and tetrachlorohydroquinone, and, in addition, a considerable amount of covalent binding to protein is detected (250 pM pentachlorophenol, 17 pM tetrachlorohydroquinone, and 11 pM tetrachlorobenzoquinone covalent binding in an incubation containing 50 μM hexachlorobenzene).

Метаболизм

Sensitized photolysis of HCB at wavelengths greater than 285 nm in acetonitrile/water containing acetone gave dechlorinated products: pentachlorobenzene (78) (71%), 1,2,3,4-tetrachlorobenzene (79) (0.6%), 1,2,3,5-tetrachlorobenzene (80) (2.2%), and 1,2,4,5- tetrachlorobenzene (81) (3.7%). Without acetone, products included pentachlorobenzene (78) (76.8%), 1,2,3,5-tetrachlorobenzene (80) (1.2%), 1,2,4,5- tetrachlorobenzene (81) (1.7%), and 1,2,4-trichlorobenzene (82) (0.2%) (105).
Irradiation of hexachlorobenzene in methanol solution at wavelengths greater than 260 nm gave a mixture of reductively dechlorinated products (pentachlorobenzene and a tetrachlorobenzene, probably 80) and pentachlorobenzyl alcohol 83, and also a tetrachlorodi( hydroxymethyl)benzene (106). A similar product mixture was obtained by exposing a methanolic solution of hexachlorobenzene inmethanol to sunlight outdoors. After 15 days, only 30% of hexachlorobenzene was recovered. Photolysis rates were enhanced by the addition of sensitizers (diphenylamine, tryptophane, and naturally occurring organic substances), but no products were identified.
In an anaerobic sewage sludge, hexachlorobenzene was reductively dechlorinated and the principal product was 1,3,5-trichlorobenzene (84). Pentachlorobenzene, 1,2,3,5- tetrachlorobenzene, and dichlorobenzenes were also identified (107). In activated sludge, 1.5% of hexachlorobenzene was mineralized as carbon dioxide after 5 days.

Перевозки

UN2729 Hexachlorobenzene, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Методы очистки

Crystallise hexachlorobenzene repeatedly from *benzene. Dry it under vacuum over P2O5. [Beilstein 5 H 205, 5 IV 670.]

Несовместимости

Reacts violently with oxidizers; dimethyl formamide above 65 ℃.

Утилизация отходов

Incineration is most effective @ 1300 ℃ and 0.25 seconds. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and waste disposal.