Hexachloro-1,3-butadiene

Overview

Hexachloro-1,3-butadiene is a colorless, oily liquid with a mild turpentine-like odor. The compound poorly dissolves in water (4mg/kg at 20°C), but miscible with ether and ethanol^[1]. Hexachloro-1,3-butadiene is found predominantly as a by-product from the manufacture of chlorinated solvents and related products and is also used in some industrial processes, such as heat transfer liquid, reactant in chemical syntheses, organic solvent, wash liquor for hydrocarbon removal^[2][3]. Hexachloro-1,3-butadiene is very stable to acids and bases, and it has no tendency to polymerize even under high pressure (e.g., 10 MPa). Hexachloro-1,3-butadiene can react with chlorine under harsh conditions (e.g., under pressure in an autoclave at 230-250 °C ), and then generally with cleavage of the carbon skeleton and formation of hexachloroethane and perchloroethylene^[4].

History and Occurrence

Hexachloro-1,3-butadiene does not exist in nature. The compound can result as a by-product from processing other chemicals. According to reports to the UN Environmental Programme, hexachloro-1,3-butadiene does not appear to be intentionally manufactured in Europe, Japan, Canada, or the United States. Intentional production in Europe ceased as early as the late 1970s. Then, production of hexachloro-1,3-butadiene has been restricted or banned in subsequent years in various other parts of the world. However, the chemical continues to be manufactured as a byproduct of chemical manufacturing^[5][6][7].

Formation

Hexachloro-1,3-butadiene can be directly synthesized through the chlorination of butadiene or butane or produced as a by-product of chlorinated hydrocarbon manufacturing, including perchloroethylene, trichloroethylene, and carbon tetrachloride ^[8]. It appears that hexachloro-1,3-butadiene, generated as a by-product during the synthesis of other compounds of interest, may be recovered or recycled for commercial purposes.

Application

It is a chlorinated aliphatic diene with several applications and commonly used as a solvent for other chlorine-containing compounds. Applications of hexachlorobutadiene in industries are extensive, used as a solvent for rubber and other polymers, in heat transfer fluids, as a transformer liquid, as a hydraulic fluid, as a solvent and to make lubricants, and as a washing liquor for removing hydrocarbons from gas streams. The uses also include as a seed dressing and fungicide and in manufacturing processes such as production of aluminium and graphite rods. Thus, the major source of hexachlorobutadiene has been reported because of inadvertent production as a waste byproduct of the manufacture of certain chlorinated hydrocarbons such as tetrachloroethylene, trichloroethylene, and carbon tetrachloride.^[9]

Processing

Hexachloro-1,3-butadiene is primarily generated as a by-product of the manufacture of chlorinated hydrocarbons, particularly perchloroethylene, trichloroethylene, and carbon tetrachloride, but it can also be produced during magnesium manufacturing via electrolysis. According to reports to the UN Environmental Programme, hexachloro-1,3-butadiene does not appear to be intentionally manufactured in Europe, Japan, Canada, or the United States. Intentional production in Europe ceased as early as the late 1970s; in various other parts of the world, production of hexachloro-1,3-butadiene has been restricted or banned in subsequent years; however, the chemical continues to be manufactured as a byproduct of chemical manufacturing^[3].
Hexachloro-1,3-butadiene may be processed for use as:

• Plastic additives^[10]
• Protective coatings^[11]
• Prepared in solvent as analytical standards^[12]
• Part of the recovery system for chlorine containing gases at chlorine plants^[13]
• Chemical intermediates in the production of rubber, chlorofluorocarbons, and lubricants^[14]

Future trends

Hexachloro-1,3-butadiene is toxic. Investigations have shown that its effects in animals are mainly restricted to the kidneys, including carcinogenicity. The effects on human populations, at low levels of exposure via inhalation, are unknown. The American National Occupational Safety and Health Administration (NIOSHA) recommends that exposure to HCBD should not exceed 20 ppb for a eight hour workday within a 40 hour working week^[15].
Hexachloro-1,3-butadiene, a man-made chlorohydrocarbon, has been listed as a candidate persistent organic pollutant (POP) by the Stockholm Convention in 2011 for its persistence, toxicity, bioaccumulation, and potential long-range transport abilities^[16].

References

1. Andre Lecloux, Eurochlor, Hexachlorobutadiene-Sources, environmental fate and risk characterisation (2004).
2. Jean Rabovsky, Evidence of the carcinogenicity of 1,3-HEXACHLOROBUTADIENE (2000).
3. Office of Chemical Safety and Pollution Prevention U.S. EPA, Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: Hexachlorobutadiene (2017).
4. Rossberg, Manfred, et al. "Chlorinated hydrocarbons." Ullmann's encyclopedia of industrial chemistry (2006).
5. https://www.dhss.delaware.gov/dph/files/hexachlbtfaq.pdf
6. US Environmental Protection Agency, Health Effects Support Document for Hexachlorobutadiene, (Washington DC: Office of Water-Health and Ecological Criteria Division, 2003).
7. United Nations Environmental Programme, Persistent Organic Pollutants Review Committee, Risk Management Evaluation on Hexachlorobutadiene (Rome: Persistent Organic Pollutants Review Committee, 2013).
8. Yang, Raymond SH. "Hexachloro-1, 3-butadiene: toxicology, metabolism, and mechanisms of toxicity." Reviews of environmental contamination and toxicology. Springer, New York, NY, 1988. 121-137.
9. Hexachlorobutadiene, Larc Monographs, 7, 277-294.
10. Chemstock, Hexachloro‐1,3‐Butadiene (Hackettstown, New Jersey: Chemstock, 2017).
11. State of Washington – Department of Ecology, Children’s Safe Product Act Reported Data (Lacey, Washington: State of Washington, 2017).
12. https://www.sigmaaldrich.com/catalog/product/sial/45525?lang=en®ion=US
13. United Nations Environmental Programme, Persistent Organic Pollutants Review Committee, Risk Management Evaluation on Hexachlorobutadiene (Rome: Persistent Organic Pollutants Review Committee, 2013).
14. US Environmental Protection Agency, Health Effects Support Document for Hexachlorobutadiene, (Washington DC: Office of Water – Health and Ecological Criteria Division, 2003).
15. Staples, B., et al. "Land contamination and urinary abnormalities: cause for concern?." Occupational and environmental medicine 60.7 (2003): 463-467.
16. Zhang, Haiyan, et al. "Levels and distributions of hexachlorobutadiene and three chlorobenzenes in biosolids from wastewater treatment plants and in soils within and surrounding a chemical plant in China." Environmental science & technology 48.3 (2014): 1525-1531.

Description

Hexachlorobutadiene was first synthesized in 1877 by chlorination of hexyl iodide. It is an industrial by-product of tetrachloroethylene, trichloroethylene, and perchloroethylene production.

Chemical Properties

Hexachlorobutadiene is a clear, colorless liquid with a faint, turpentine-like odor.

Chemical Properties

colourless liquid (typical odour recognition threshold:

Physical properties

Clear, yellowish-green liquid with a mild to pungent, turpentine-like odor. Odor threshold concentration is 6 ppb (quoted, Keith and Walters, 1992).

Uses

Produced as an unwanted by-product during the production of tetrachloroethylene, trichloroethylene, carbon tetrachloride, and chlorine; formerly used as a pesticide in other countries

Uses

Hexachloro-1,3-butadiene is used as an urinary biomarker as a tool for early screening of potential kidney toxicity. Hexachloro-1,3-butadiene (HCBD) causes kidney injury.

Uses

Intermediate in the manufacture of rubber Compounds, chlorofluorocarbons, and lubricants. Hydraulic fluid, fluid for gyroscopes, heat transfer fluid, solvent, laboratory reagent. Soil fumigant for vineyards.

Definition

ChEBI: Hexachloro-1,3-butadiene is an organochlorine compound.

General Description

A colorless liquid with a mild odor. Insoluble in water and denser than water. Nonflammable. May be toxic by ingestion or inhalation. Used as a solvent and heat transfer fluid.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Hexachloro-1,3-butadiene rapidly decomposes rubber on contact. Can react vigorously with oxidizing materials. Reacts to form an explosive product with bromine perchlorate. . Gives highly toxic and irritating chloride fumes when burned.

Hazard

Toxic by ingestion and inhalation, a questionable carcinogen.

Health Hazard

Poisonous; may be fatal if inhaled, swallowed or absorbed through the skin. Inhalation causes repiratory difficulty and irritation of mucous membranes. Skin and eye irritant; may cause burns.

Potential Exposure

Hexachlorobutadiene is used as a sol vent; heat-transfer fluid; transformer fluid; hydraulic fluid; as a solvent for elastomers; as a wash liquor for removing higher hydrocarbons.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek med-icalattention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, includ-ing resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medi-cal attention. Give large quantities of water and induce :vomiting. Do not make an unconscious person vomit.

Carcinogenicity

In rats given oral administration, it produced benign and malignant tumors in the kidneys in both sexes. The IARC then concluded that there is limited evidence that HCBD is carcinogenic in rats.
Nakagawa et al. reported that HCBD is a potent nephrotoxicant that selectively damaged the straight portion (pars recta) of the proximal tubule in the rat. They also reported administering 0.1% HCBD for 30 weeks to male Wistar rats previously given 0.1% N-ethyl-N-hydroxyethylnitrosamine (EHEN) in their drinking water for 2 weeks and that the combined treatment resulted in a significantly higher incidence of renal cell tumors than when EHEN was administered alone.

Source

Hydraulic fluids and rubber (quoted, Verschueren, 1983). An impurity in aldrin.

Environmental Fate

Chemical/Physical. Hexachlorobutadiene will not hydrolyze to any reasonable extent (Kollig, 1993).
At influent concentrations of 1.0, 0.1, 0.01, and 0.001 mg/L, the GAC adsorption capacities were 258, 91, 21, and 11 mg/g, respectively (Dobbs and Cohen, 1980).

Metabolic pathway

In the presence of glutathione (GSH), mouse liver microsomes and cytosol transform 14C-hexachloro- 1,3-butadiene (HCBD) to S- (pentachlorobutadienyl)glutathione (PCBG). PCBG formation in subcellular fractions from a mouse kidney is very limited. After an oral dose of HCBD to mice, PCBG in feces, and S-(pentachlorobutadienyl)-L- cysteine, N-acetyl-S-(pentachlorobutadienyl)-L- cysteine, and 1,1,2,3-tetrachlorobutenoic acid in the urine are identified as the metabolites.

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 lated area away from oxidizers. Where possible, auto-matically pump liquid from drums or other storage contain-ers to process containers A regulated, marked area shouldbe established w here hex achlorobutadiene is handled, used,or stored. A regulated, marked area should be establi shedwhere this chemical is handled, used, or stored in compli-ance with OSHA Standard 1910. 1045.

Shipping

UN2279 Hexachlorobutadiene, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Purification Methods

Wash the diene with four or five 1/10th volumes of MeOH (or until the yellow colour has been extracted), then stir it for 2hours with H2SO4, wash it with distilled water until neutral and filter it through a column of P2O5. Distil it under reduced pressure through a packed column. [Rytner & Bauer J Am Chem Soc 82 298 1960, Beilstein 1 IV 998.]

Toxicity evaluation

Hexachlorobutadiene specifically damages the pars recta portion of the proximal tubule with loss of the brush border. The mechanism involves nonoxidative formation of the glutathione conjugate in liver with subsequent transport to the kidney for mercapturic acid conjugate excretion. The resulting cysteine conjugates are substrates for cysteine-conjugate b-lyase, which removes ammonia and pyruvate from the cysteine conjugate to produce thionylacyl halides and thioketenes. These toxic thiol compounds can then bind covalently to proteins and DNA in proximal tubular cells to produce nephrotoxicity. S-(1,2,3,4,4- Pentachloro-1,3-butadienyl)-L-cysteine has been identified as the ultimate metabolite responsible for hexachlorobutadieneinduced nephrotoxicity. Mitochondrial dysfunction is reported to be the ultimate subcellular toxic lesion. Enterohepatic recirculation of hexachlorobutadiene–glutathione conjugates is believed to play a major role in this mechanism, since cannulation of the bile duct of rats prevents nephrotoxicity.

Incompatibilities

Strong reaction with oxidizers, aluminum powder. Attacks aluminum; some plastics, rubber and coatings

Waste Disposal

High temperature incineration with flue gas scrubbing. 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.