Hexachlorocyclopentadiene

Description

Hexachlorocyclopentadiene is a pale-yellow/lemon-yellow liquid with a characteristic musty or pungent odour (odour threshold – 0.03 ppm). Hexachlorocyclopentadiene does not occur naturally but is a manufactured chemical. It easily evaporates into the air. Hexachlorocyclopentadiene is the key intermediate in the manufacture of some pesticides, including heptachlor, chlordane, aldrin, dieldrin, and endrin. Hexachlorocyclopentadiene is also used in the manufacture of flame retardants and some resins, shock-proof plastics, fluorocarbons, and dyes. Hexachlorocyclopentadiene quickly breaks down by sunlight and reacts with other chemicals in the air.

Chemical Properties

Hexachlorocyclopentadiene is a pale-yellow to amber-colored, oily liquid. Pungent, unpleasant odor. The odor threshold is 0.15 0.33 ppm. Insoluble in water, soluble in ether, carbon tetrachloride and other organic solvents.

Uses

Hexachlorocyclopentadiene is an organochlorine compound that is used to manufacturing organochlorine insecticides and acaricides, such as mirex, aldrin, dieldrin, chlordane, endosulfan, etc. It is also used to make flame retardants, resins that won't burn, shock-proof plastics, esters, ketones, fluorocarbons, and dyes.

Preparation

Hexachlorocyclopentadiene is obtained by chlorination of cyclopentadiene in two steps. In addition, using petroleum pentane as raw material, hexachlorocyclopentadiene is synthesized by photochlorination and high temperature chlorination, and the yield is about 70%.

Application

Hexachlorocyclopentadiene(Hex) is an Intermediate in the manufacture of chlorinated pesticides and flame retardants. The principal end use for Hex is as a key intermediate in the production of chlorinated cyclodiene pesticides, including aldrin, dieldrin, endrin, chlordane, heptachlor, kepone, endosulfan, pentac, isodrin, and mirex. It is also used as an intermediate in the manufacture of flame retardants such as Dechlorane Plus and chlorendic anhydride and, to a lesser extent, in the manufacture of nonflammable resins, polyester resins, pharmaceuticals, unbreakable plastics, acids, esters, ketones, fluorocarbons, and dyes.

General Description

A pale yellow liquid with a pungent odor. Density 14.3 lb /gal. Solidifies at 50°F. Insoluble in water. Noncombustible. Very toxic by skin absorption and inhalation. Corrosive to tissue.

Air & Water Reactions

Insoluble in water. Reacts slowly with water to form hydrochloric acid.

Reactivity Profile

Hexachlorocyclopentadiene is incompatible with strong oxidizing and reducing agents. Also incompatible with many amines, nitrides, azo/diazo compounds, alkali metals (sodium), and epoxides.

Health Hazard

Hexachlorocyclopentadiene is very toxic and may be fatal if inhaled, swallowed, or absorbed through the skin. The probable human lethal dose is 50-500 mg/kg, or between 1 teaspoon and 1 ounce for a 150 lb. (70 kg) person. Severe exposure induces pulmonary hyperemia and edema, degenerative and necrotic changes in brain, heart and adrenal glands and necrosis of liver and kidney tubules. Questionable carcinogen.

Fire Hazard

Toxic hydrogen chloride, chlorine, and phosgene gases may form in fires. In presence of moisture, will corrode iron and other materials; flammable and explosive hydrogen gas may collect in enclosed space. Will corrode iron and other metals in the presence of moisture. Reacts slowly with water to form hydrochloric acid; however, the reaction is not hazardous. Hazardous polymerization may not occur.

Safety

Hexachlorocyclopentadiene is a manufactured chemical that does not occur naturally. Hex has no end uses of its own, and is very toxic following acute (short-term) oral and inhalation exposures. It easily evaporates into the air; the vapor looks like a blue haze. Most of the Hexachlorocyclopentadiene in the environment results from its release during production and disposal. Animal tests suggest that very high levels can cause death. Human data are limited, but it can cause headaches and irritate the nose, throat, eye, and skin.

Potential Exposure

Hexachlorocyclopentadiene is used to produce the flame retardant chlorendic anhydride, which has applications in polyesters; and to produce chlorendic anhydride and chlorendic acid; which is used as a flame retardant in resins. Hexachlorocyclopentadiene is also used as an intermediate in the production of pesticides, such as aldrin, dieldrin, and endosulfan.

First aid

If this chemical gets into the eyes, remove any con-tact lenses at once and irrigate immediately for at least 15 min,occasionally lifting upper and lower lids. Seek medical atten-tion immediately. If this chemical contacts the skin, removecontaminated clothing and wash immediately with soap andwater. Speed in removing material from the skin is of extremeimportance. Seek medical attention immediately. If this chem-ical has been inhaled, remove from exposure, begin rescuebreathing (using universal precautions, including resuscitationmask) if breathing has stopped and CPR if heart action hasstopped. Transfer promptly to a medical facility. When thischemical has been swallowed, get medical attention. Givelarge quantities of water and induce vomiting. Do not make anunconscious person vomit. Keep victim quiet and maintainnormalbody temperature. Medical observation is recom-mended for 24- 48 h after breathing overexposure, as pulmo-nary edema may be delayed. As first aid for pulmonaryedema, a doctor or authorized paramedic may consider admin-istering a corticosteroid spray.

Environmental Fate

Biological. When hexachlorocyclopentadiene (5 and 10 mg/L) was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum for 7 d, 100% biodegradation with rapid adaptation was observed (Tabak et al., 1981). In a model ecosystem containing plankton, Daphnia magna, mosquito larva (Culex pipiens quinquefasciatus), fish (Cambusia affinis), alga (Oedogonium cardiacum), and snail (Physa sp.), hexachlorocyclopentadiene degraded slightly, but no products were identified (Lu et al., 1975).
Photolytic. The major photolysis and hydrolysis products identified in distilled water were pentachlorocyclopentenone and hexachlorocyclopentenone. In mineralized water, the products identified include cis- and trans-pentachlorobutadiene, tetrachlorobutenyne, and pentachloropentadienoic acid (Chou and Griffin, 1983). In a similar experiment, irradiation of hexachlorocyclopentadiene in water by mercury-vapor lamps resulted in the formation of 2,3,4,4,5- pentachloro-2-cyclopentenone. This compound hydrolyzed partially to hexachloroindenone (Butz et al., 1982). Other photodegradation products identified include hexachloro-2-cyclopentenone and hexachloro-3-cyclopentenone as major products. Secondary photodegradation products reported include pentachloro-cis-2,4-pentadienoic acid, Z- and E-pentachlorobutadiene, and tetrachlorobutyne (Chou et al., 1987). In natural surface waters, direct photolysis of hexachlorobutadiene via sunlight results in a half-life of 10.7 min (Wolfe et al., 1982).
Chemical/Physical. Slowly reacts with water forming HCl and 1,1-dihydroxytetrachlorocyclopentadiene (Kollig, 1993; NIOSH, 1997). The diene is unstable forming polymers (Kollig, 1993).

Solubility in organics

Based on structurally similar compounds, hexachlorocyclopentadiene is expected to be soluble in benzene, ethanol, chloroform, methylene chloride, trichloroethylene, and other liquid halogenated solvents.

storage

Color Code- -Blue: Health Hazard/Poison: Storein a secure poison location. Prior to working with thischemical you should be trained on its proper handling andstorage. Store in tightly closed containers in a cool, well-venti latedarea away from water. Protect containers fromphysical damage. In the presence of moisture, hexachloro-cyclopentadiene will corrode iron and other metals.

Shipping

UN2646 Hexachlorocyclopentadiene, Hazard Class: 6.1; Labels: 6.1-Poison Inhalation Hazard, Inhalation Hazard Zone B.

Purification Methods

Dry the diene with MgSO4, filter, and distil it under vacuum in a nitrogen atmosphere. Irritates skin and eyes, HIGHLY TOXIC. [McBee et al. J Am Chem Soc 77 4378 1955, UV spectra: Idol et al. J Org Chem 20 1746 1955, Beilstein 5 III 308, 5 IV 381.]

Toxicity evaluation

Hex’s mechanism of toxicity is incompletely understood. Because of its characteristics as a chlorinated hydrocarbon, it would be expected to induce drug-metabolizing enzymes in the liver.

Incompatibilities

Reacts slowly with water to form hydro chloric acid; will corrode iron and most metals in presence of moisture. Explosive hydrogen gas may collect in enclosed spaces in the presence of moisture. Contact with sodium may be explosive.

Waste Disposal

Incineration 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 pro duced. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must con form to EPA regulations governing storage, transportation, treatment, and waste disposal.