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Hexachlorocyclopentadiene Basic information
Hexachlorocyclopentadiene Chemical Properties
  • Melting point:−10 °C(lit.)
  • Boiling point:239 °C753 mm Hg(lit.)
  • Density 1.702 g/mL at 25 °C(lit.)
  • vapor pressure 0.13 psi ( 20 °C)
  • refractive index n20/D 1.5644(lit.)
  • Flash point:109 °C
  • storage temp. 2-8°C
  • form Yellow to amber-colored liquid
  • Water Solubility 805ug/L(22.5 ºC)
  • Henry's Law Constant1.64(x 10-2 atm?m3/mol) at 25 °C (gas stripping-GC, Warner et al., 1987) 1.6(x 10-2 atm?m3/mol) (Pankow and Rosen, 1988)
  • Exposure limitsNIOSH REL: 10 ppb (100 mg/m3); ACGIH TLV: TWA 0.01 ppm (adopted), 0.002 mg/m3 ppm (skin).
  • Stability:Stability Stable, but light-sensitive. Non-flammable. Very reactive with alkenes and polynuclear hydrocarbons. Explosive with sodium. Incompatible with strong oxidizing agents, most common metals.
  • CAS DataBase Reference77-47-4(CAS DataBase Reference)
  • NIST Chemistry Reference1,3-Cyclopentadiene, 1,2,3,4,5,5-hexachloro-(77-47-4)
  • EPA Substance Registry SystemHexachlorocyclopentadiene (77-47-4)
Safety Information
Hexachlorocyclopentadiene Usage And Synthesis
  • DescriptionHexachlorocyclopentadiene 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 PropertiesPale-yellow liquid; pungent odor. Nonflammable.
  • Chemical PropertiesHexachlorocyclopentadiene is a pale-yellow to amber-colored, oily liquid. Pungent, unpleasant odor. The odor threshold is 0.15 0.33 ppm.
  • Physical propertiesPale yellow to greenish-yellow liquid with a harsh, unpleasant odor. Odor threshold concentrations ranged from 1.4 to 1.6 μg/L (quoted, Keith and Walters, 1992).
  • UsesIntermediate in the manufacture of chlorinated pesticides; intermediate in the manufacture of flame retardants
  • UsesEnvironmental neurotoxicant. Used in the preparation of some insecticides, flame retardants, and resins.
  • UsesThe 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. Technical grade chlordane, for example, has been reported to contain impurities of Hex up to 1%. 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. It has previously been used as a biocide.
  • UsesHexachlorocyclopentadiene (Hex) (molecular weight 272.77) is an organochlorine compound that is used as a raw material in manufacturing other chemicals, including pesticides, flame retardants, resins, dyes, pharmaceuticals, plastics, etc. Hex 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 is a light, lemon-yellow liquid that has a sharp musty odor. It easily evaporates into the air; the vapor looks like a blue haze. Most of the Hex in the environment results from its release during production and disposal. It is also used to make flame retardants, resins that won’t burn, shock-proof plastics, esters, ketones, fluorocarbons, and dyes. 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.
  • General DescriptionA 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 ReactionsInsoluble in water. Reacts slowly with water to form hydrochloric acid.
  • Reactivity ProfileHexachlorocyclopentadiene is incompatible with strong oxidizing and reducing agents. Also incompatible with many amines, nitrides, azo/diazo compounds, alkali metals (sodium), and epoxides.
  • HazardToxic by ingestion, inhalation, and skin absorption. Questionable carcinogen.
  • Health HazardHexachlorocyclopentadiene 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.
  • Fire HazardToxic 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.
  • Potential ExposureHexachlorocyclopentadiene 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.
  • Environmental FateBiological. 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 organicsBased on structurally similar compounds, hexachlorocyclopentadiene is expected to be soluble in benzene, ethanol, chloroform, methylene chloride, trichloroethylene, and other liquid halogenated solvents.
  • Solubility in waterBased on structurally similar compounds, hexachlorocyclopentadiene is expected to be soluble in benzene, ethanol, chloroform, methylene chloride, trichloroethylene, and other liquid halogenated solvents.
  • ShippingUN2646 Hexachlorocyclopentadiene, Hazard Class: 6.1; Labels: 6.1-Poison Inhalation Hazard, Inhalation Hazard Zone B.
  • Purification MethodsDry 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 evaluationHex’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.
  • IncompatibilitiesReacts 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 DisposalIncineration 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.
Hexachlorocyclopentadiene Preparation Products And Raw materials
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