ГЕПТАХЛОР

Описание

Heptachlor is a soft, white to light tan, waxy, non-combustible, crystalline solid with a camphor-like odour. Heptachlor is a member of the cyclodiene group of chlorinated insecticides (aldrin, dieldrin, endrin, chlordane, heptachlor, and endosulfan) and has a long history following World War II. It was registered as a commercial pesticide in 1952 for foliar, soil, and structure applications and for malarial control programmes; after 1960, it was used primarily in soil applications against agricultural pests and to a lesser extent against termites. Heptachlor is available commercially as a dust, a dust concentrate, an emulsifiable concentrate, a wettable powder, or in oil solutions. It is corrosive to metals and reacts with iron and rust to form hydrogen chloride gas. Heptachlor is incompatible with many amines, nitrides, azo/diazo compounds, alkali metals, and epoxides but is stable under normal temperatures and pressures. It may burn, but does not ignite readily. Heptachlor at high heat and temperature produces highly toxic, corrosive fumes of hydrogen chlorine gas and toxic oxides of carbon. An important metabolite of heptachlor is heptachlor epoxide which is an oxidation product formed from heptachlor by many plant and animal species. Heptachlor is almost insoluble in water but soluble in ether, acetone, benzene, and many other organic solvents.

Химические свойства

Heptachlor is an organochlorine cyclodiene insecticide isolated from technical chlordane. It is available in the form of white crystals or a tan-colored waxy solid with a characteris- tic camphor-like or cedar-like odor. It is sparingly soluble or insoluble in water, but fairly soluble in acetone, benzene, ethanol, xylene, and other organic solvents. It is used for the control of termites, ants, and soil insects in cultivated and non-cultivated soils. Heptachlor epoxide is formed in nature when heptachlor is released into the environment and mixes with oxygen. Heptachlor epoxide remains in the soil for long periods of time. Heptachlor and heptachlor epoxide may also be present at numerous hazardous waste sites. Although the use of heptachlor is restricted, exposure to the general population does occur through the ingestion of contaminated food.

Физические свойства

Colorless to light tan, waxy or crystalline, nonflammable solid with a camphor-like odor

Использование

Heptachlor is used for the control of termites, ants, household insects and soil insects. It is also applied as a seed treatment, soil treatment or directly to foliage.

Подготовка

Heptachlor may be synthesized by reacting chlordene with N-bromosuccinimide to give the intermediate 1-bromochlordene followed by chlorination with hydrogen chloride in nitromethane in the presence of aluminum trichloride.

Определение

ChEBI: A cyclodiene organochlorine insecticide that is 3a,4,7,7a-tetrahydro-1H-4,7-methanoindene substituted by chlorine atoms at positions 1, 4, 5, 6, 7, 8 and 8. Formerly used to kill termites, ants and other insects in agricultural and domes ic situations.

Общее описание

HEPTACHLOR is a white to light tan waxy looking solid. Noncombustible. Insoluble in water. Can cause illness by inhalation, skin absorption and/or ingestion. The primary hazard is the threat posed to the environment. Immediate steps should be taken to limit its spread to the environment. Used as an insecticide.

Реакции воздуха и воды

Susceptible to epoxidation. Insoluble in water. Slowly losses hydrogen chloride in the presence of alkaline solution.

Профиль реактивности

HEPTACHLOR is incompatible with strong alkalis. Corrosive to metals. Can react with iron and rust to form toxic gases. Can react vigorously with oxidizing materials. Susceptible to epoxidation . May be incompatible with many amines, nitrides, azo/diazo compounds, alkali metals, and epoxides.

Опасность

Toxic by ingestion, inhalation, and skin absorption; use has been restricted and discontinued except for termite control. Possible carcinogen.

Угроза здоровью

Exposures to heptachlor epoxide cause adverse health effects to animals and humans. Exposure to heptachlor is toxic by mouth, by skin contact, as well as by inhalation of dust from powder concentrates. Heptachlor acts as a CNS stimulant. Prolonged period of expo- sures to high concentrations of heptachlor cause headache, dizziness, nausea, vomiting, weakness, irritability, salivation, lethargy, respiration distress, muscle tremors, convul- sions, and paralysis. Severe cases of poisoning lead to respiratory failure and death. In fact, seizures and cortical excitability are the prime CNS symptoms following acute hepta- chlor exposure. The photoisomer of heptachlor (photoheptachlor) and the major metabo- lite of heptachlor, namely, heptachlor epoxide are more toxic than the parent compound. Heptachlor induces tremors, convulsions, paralysis, and hypothermia in rats and young calves. The poisoned animals showed muscle spasms in the head and neck region, convul- sive seizures, elevated body temperatures, and engorged brain blood vessels. Humans exposed to heptachlor in the home during termite control operations showed signs of neurotoxicity, i.e., irritability, salivation, lethargy, dizziness, labored respiration, muscle tremors, convulsions, and death due to respiratory failure. Heptachlor interfered with nerve transmission, caused hyperexcitation of the CNS, lethargy, incoordination, tremors, convulsions, stomach cramps or pain, leading to coma and death.

Пожароопасность

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

Метаболический путь

Heptachlor is quite stable and resistant to environmental degradation. Metabolic processes by which it undergoes transformation are epoxidation, hydrolysis and dechlorination. It is transformed into a variety of products, many of which differ from one another only in stereochemical features while retaining the carbon skeleton and the chlorinated norbornene moiety. The main biological metabolite is exoepoxyheptachlor. Products formed by sensitised photolysis have caged structures and undergo reactions that are typical of this class.