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CAS Number: 87-68-3 
EC Number : 201-765-5
ECHA InfoCard    : 100.001.605 
PubChem CID :  6901
ChEMBL     : ChEMBL389950 
ChemSpider    : 6635 
KEGG     : C11091 
Chemical formula :     C4Cl6
Molar mass :     260.76 g/mol
Appearance    : Colorless liquid
Odor :     Mild, turpentine-like
Density    : 1.665 g/mL at 25 ℃
Melting point    : -22 - -19 ℃
Boiling point    : 210-220 ℃
Vapor pressure    : 0.2 mmHg (20°C)
IUPAC name : Hexachloro-1,3-butadiene

Hexachlorobutadiene, Cl2C=C(Cl)C(Cl)=CCl2, is a colorless liquid at room temperature that has an odor similar to that of turpentine. 
Hexachlorobutadiene is a chlorinated aliphatic diene with niche applications but is most commonly used as a solvent for other chlorine-containing compounds.

Synthesis of Hexachlorobutadiene
Hexachlorobutadiene, or HCBD, is primarily produced in chlorinolysis plants as a by-product in the production of carbon tetrachloride and tetrachloroethene. 
Chlorinolysis is a radical chain reaction that occurs when hydrocarbons are exposed to chlorine gas under pyrolytic conditions. 
The hydrocarbon is chlorinated and the resulting chlorocarbons are broken down. 
This process is analogous to combustion, but with chlorine instead of oxygen.

Hexachlorobutadiene occurs as a by-product during the chlorinolysis of butane derivatives in the production of both carbon tetrachloride and tetrachloroethene. 
These two commodities are manufactured on such a large scale, that enough HCBD can generally be obtained to meet the industrial demand. 
Alternatively, hexachlorobutadiene can be directly synthesized via the chlorination of butane or butadiene.

Reactivity of Hexachlorobutadiene
The products of chlorinolysis reactions heavily depend upon both the temperature and pressure under which the reaction occurs. 
Thus, by adjusting these reaction conditions in the presence of chlorine gas, hexachlorobutadiene can be even further chlorinated to give tetrachloroethylene, hexachloroethane, octachlorobutene, and even decachlorobutane. 
In general, increasing the number of chlorine substituents on a compound increases its toxicity but decreases its combustibility. 
Chlorination via carbon skeleton cleavage is thermodynamically preferred, whereas chlorinated C4 products are favored at lower temperatures and pressures. 
The three chlorinolysis products of hexachlorobutadiene are shown in the reactions below.

Applications of Hexachlorobutadiene
One of the primary applications of hexachlorobutadiene is as a solvent for chlorine, a good illustration of the common aphorism "like dissolves like."
The molar solubility of chlorine in HCBD at 0 °C is around 34% (2.17 mol/L). 
The solubility of another chlorine solvent, carbon tetrachloride, at 0 °C is about 30% (3.11 mol/L). 

One mole of C4Cl6 can dissolve more chlorine than one mole of CCl4, 
but the molecular weight difference between the two solvents is such that per liter of solvent, more chlorine can be dissolved in carbon tetrachloride. 
Shown below is the molar solubility of hexachlorobutadiene compared to carbon tetrachloride at various temperatures.

Temp (C)    Molar Solubility of HCBD   Molar Solubility of CCl4
-20                     60                         60
0                     34                         30
20                     21                         18
40                     13                         10
60                     10                          8
80                      6                          5

Just like chlorine, many other chlorine-containing compounds can be readily dissolved in a solution of hexachlorobutadiene. 
As a solvent, it is unreactive toward common acids and select non-nucleophilic bases. 
An illustrative application HCBD as a solvent is the FeCl3-catalyzed chlorination of toluene to give pentachloromethylbenzene. 
Hexachlorobutadiene is used exclusively over carbon tetrachloride in this reaction because ferric chloride (FeCl3) is insoluble in CCl4.

Given its affinity for chlorinated compounds, liquid HCBD is used as a scrubber in order to remove chlorine containing contaminants from gas streams. 
An example of this application is its use in the production of HCl gas as the primary contaminants, especially Cl2, are more soluble in hexachlorobutadiene than the gaseous hydrogen chloride.
In IR spectroscopy, hexachlorobutadiene is occasionally used as a mull in order to analyze the stretching frequencies of C-H stretching bands. 

The usual mulling agent, Nujol, is a hydrocarbon and thus exhibits C-H stretching bands that can interfere with the signal from the sample. 
Since HCBD contains no C-H bonds, it can be used instead to obtain this portion of the IR spectrum. 
Unfortunately, some organometallic compounds react with HCBD, and therefore, care must be taken when selecting it as a mulling agent so as not to destroy the sample.
Hexachlorobutadiene has yet another, albeit somewhat dated, application as an algicide in industrial cooling systems. 
Although HCBD is a potent herbicide, in recent years, this particular application has been discouraged due to the high toxicity of the compound at low concentrations.

Toxicity of Hexachlorobutadiene
Hexachlorobutadiene has been observed to produce systemic toxicity following exposure via oral, inhalation, and dermal routes. 
Effects may included fatty liver degeneration, epithelial necrotizing nephritis, central nervous system depression and cyanosis. 

The carcinogenicity of hexachlorobutadiene has been classified by the United States Environmental Protection Agency  has classified hexachlorobutadiene as a group C Possible Human Carcinogen. 
The American Conference of Governmental and Industrial Hygienists has classified hexachlorobutadiene as an A3 Confirmed Animal Carcinogen with Unknown Relevance to Humans. 
The National Institute for Occupational Safety and Health has set a recommended exposure limit at 0.02 ppm over an eight-hour workday.

Hexachlorobutadiene is a colorless liquid with a turpentine-like odor. 
Hexachlorobutadiene  is also called perchlorobutadiene. 
Hexachlorobutadiene is not found naturally in the environment. 
Hexachlorobutadiene  is formed when other chemicals are made. 
Most hexachlorobutadiene used commercially in the United States is imported from Germany. 
Hexachlorobutadiene  is mainly used to make rubber compounds. 
Hexachlorobutadiene  is also used as a solvent, and to make lubricants, in gyroscopes, as a heat transfer liquid, and as a hydraulic fluid.

Hexachlorobutadiene appears as a colorless liquid with a mild odor. 
Hexachlorobutadiene is insoluble in water and denser than water. 
Hexachlorobutadiene is nonflammable. 
Hexachlorobutadiene may be toxic by ingestion or inhalation. 
Hexachlorobutadiene used as a solvent and heat transfer fluid.

Hexachlorobutadiene is used mainly as an intermediate in the manufacture of rubber compounds. 
No information is available on the health effects of hexachlorobutadiene in humans. 
Animal studies have reported effects on the kidney and respiratory system from acute inhalation exposure, and effects on the kidney from chronic oral exposure to hexachlorobutadiene. 
Animal studies have not reported developmental or reproductive effects, other than a reduction in fetal body weights, from inhalation exposure to hexachlorobutadiene. 
One study reported kidney tumors in rats exposed to hexachlorobutadiene orally. 
EPA has classified hexachlorobutadiene as a Group C, possible human carcinogen.

Physical Description of Hexachlorobutadiene
Hexachlorobutadiene appears as a colorless liquid with a mild odor. 
Insoluble in water and denser than water. 
May be toxic by ingestion or inhalation. 
Used as a solvent and heat transfer fluid.

Manufacturing of Hexachlorobutadiene
Hexachlorobutadiene (HCBD) 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 recent reports to the UN Environmental Programme, HCBD 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 HCBD has been restricted or banned in subsequent years; however, the chemical continues to be manufactured as a byproduct of chemical manufacturing.

Various methods for HCBD synthesis have been described in two patents. HCBD 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. 
It appears that HCBD, generated as a by‐product during the synthesis of other compounds of interest, may be recovered or recycled for commercial purposes.

In addition to  HCBD has been reported by manufacturers as a contaminant in various children’s products under the State of Washington’s Children’s Safe Product Act. 
Reporting indicates that HCBD is present in feeding and hygiene products, clothing, fabrics and furnishings, accessories, footwear, toys, and games.
HCBD is also mentioned in 1290 patents.

Processing of Hexachlorobutadiene
HCBD may be processed for use as:
Plastic additives
Protective coatings
Prepared in solvent as analytical standards
Part of the recovery system for chlorine containing gases at chlorine plants
Chemical intermediates in the production of rubber, chlorofluorocarbons, and lubricants.

Industrial Uses of Hexachlorobutadiene
The following industrial uses, including historical and/or potential uses, of HCBD have been identified:
Heat transfer liquid
Reactant in chemical syntheses 
Organic solvent
Wash liquor for hydrocarbon removal
Chlorine recovery
Rubber vulcanization
Manufacture of aluminum and graphite rods.
Manufacture of carbon spheres25
Manufacture of photopolymerized films
Preparation of organosilicon polymers.

Commercial Uses of Hexachlorobutadiene
The following commercial uses, including historical and/or potential uses, of HCBD have been identified:
Pesticides/agricultural fumigants
Hydraulic fluid
Gyroscope fluid
Laboratory reagent.

Consumer Uses of Hexachlorobutadiene
While no consumer uses of HCBD have been identified, the following products contain or have been previously shown to contain HCBD:
Children’s clothing and headgear36

Disposal of Waste and Recycling/Recovery of Hexachlorobutadiene
According to TRI data for the 2015 reporting year, 2,311 lbs. of HCBD were released on‐site to air, 10 lbs. released on‐site to landfills and 174 lbs. were transferred off‐site for disposal. 
TRI data shows that 10,619,094 lbs. of HCBD was generated in waste, with 284,435 lbs. being recycled on‐site, 27,280 burned for energy recovery on‐site, and 10,278,244 lbs. treated for destruction on‐site.
Off‐site waste management of HCBD includes 25 lbs. burned for energy recovery and 26,615 lbs. treated for destruction.  
HCBD is a Hazardous Waste under the Resource Conservation and Recovery Act (RCRA) with Hazardous Waste Number U128.

Hexachlorobutadiene is a colorless liquid with an odor similar to turpentine. 
Hexachlorobutadiene evaporates easily. 
This chemical is also called hexachloro-1,3-butadiene, HCBD, perchlorobutadiene, 1,3- hexachlorobutadiene or Dolen-Pur.

Hexachlorobutadiene does not occur in nature. 
It has never been produced as a commercial product in the United States. 
It can result as a by-product from processing other chemicals. 
Some quantities of hexachlorobutadiene are imported, mostly from Germany.
Hexachlorobutadiene is used to manufacture rubber, chlorofluorocarbons and lubricants. 
It is used in fluids for transformers, hydraulics, gyroscopes and heat transfer processes. 
Hexachlorobutadiene is also used in solvents, in laboratory processes and in industrial processes.

You could be exposed to hexachlorobutadiene through:
Breathing hexachlorabutadiene vapors where it is made or used, or around hazardous waste sites where it was disposed.
Eating fish or other food in contact with hexachlorabutadiene.
Drinking water polluted with hexachlorabutadiene.
Touching hexachlorobutadiene or water containing it.

Studies have not tested the effects of hexachlorabutadiene on humans. 
Mice that breathed hexachlorobutadiene for a short time showed nasal irritation. 
The only other effect seen in animal studies was low birth weight babies from mothers who breathed high levels.
Long-term exposure of low hexachlorobutadiene levels was also studied using animals. 

Rats and mice that drank low levels of hexachlorobutadiene over both the short and a long term had kidney and liver damage.
Studies with rabbits found kidney and liver damage from short-term skin contact with hexachlorobutadiene.
Hexachlorobutadiene was named as a possible cancer-causing substance.
There is no treatment for hexachlorobutadiene poisoning. 
A doctor will treat the symptoms.

If you touch hexachlorobutadiene, remove contaminated clothing. 
Wash skin with soap and water. 
Get medical help.
If hexachlorobutadiene gets in your eyes, rinse your eyes with water for 15 minutes. 
Get medical help.
If you breathe hexachlorobutadiene, move to fresh air. 
Get medical help.

Limit occupational exposure by using engineering controls, such as enclosing processes and ensuring healthy ventilation. 
Follow health and safety procedures. 
Wear respirators, protective clothing and eye protection.
People living near facilities that use or produce hexachlorobutadiene as a by-product (or who live near disposal sites contaminated with the hexachlorobutadiene) can reduce their exposure by avoiding handling contaminated soil. 
If the drinking water is contaminated, drink only bottled water.

Hexachlorobutadiene (C4Cl6; CAS No. 87-68-3) is a colorless liquid with a turpentine-like odor with an odor threshold of approximately 1 ppm. 
The main source of hexachlorobutadiene in the United States is its production as a byproduct of chlorinated hydrocarbon synthesis.
Low levels of hexachlorobutadiene can be detected in air, water, and sediment. 
Atmospheric levels of hexachlorobutadiene in rural and urban air samples typically range from 2 to 11 ppt, with a mean value of 2–3 ppt. 
Higher levels can be detected at areas near industrial and chemical waste disposal sites and production sites. 

Hexachlorobutadiene is infrequently detected in ambient waters, but has been detected in drinking water at levels of 2–3 ppt. 
Sediments contain higher levels of hexachlorobutadiene than the waters from which they were obtained. 
Foodstuffs generally do not contain detectable levels of hexachlorobutadiene, except for fish in which concentrations of 0.1–4.7 mg/kg have been reported. 
Thus, exposure can occur through ingestion of contaminated water or food or inhalation of contaminated air.
Hexachlorobutadiene has been detected in human adipose tissue and blood samples, although general population monitoring data are not available.

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 β-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 hexachlorobutadiene-induced 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.

Hexachlorobutadiene can affect you when breathed in and may be absorbed through the skin.
* Hexachlorobutadiene should be handled as a CARCINOGEN--WITH EXTREME CAUTION.
* Contact can irritate and burn the skin and eyes with possible eye damage.
* Breathing Hexachlorobutadiene can irritate the nose and throat.
* Exposure to Hexachlorobutadiene can cause headache, dizziness, tremors and even a coma.
* Hexachlorobutadiene can irritate the lungs. 
Repeated exposure may cause bronchitis to develop with cough, phlegm, and/or shortness of breath.
* Hexachlorobutadiene may damage the liver and kidneys.

Hexachlorobutadiene is on the Hazardous Substance List because it is cited by ACGIH, DOT, NIOSH, DEP, IRIS NFPA and EPA.
This chemical is on the Special Health Hazard Substance List because it is a CARCINOGEN.
Hexachlorobutadiene may be a CARCINOGEN in humans. 
There may be no safe level of exposure to a carcinogen, so all contact should be reduced to the lowest possible level.
The above exposure limits are for air levels only. 
When skin contact also occurs, you may be overexposed, even though air levels are less than the limits listed above. 
Enclose operations and use local exhaust ventilation at the site of chemical release. 
If local exhaust ventilation or enclosure is not used, respirators should be worn.
* Wear protective work clothing.
* Wash thoroughly immediately after exposure to Hexachlorobutadiene and at the end of the workshift.
* Post hazard and warning information in the work area. 
In addition, as part of an ongoing education and training effort, communicate all information on the health and safety hazards of Hexachlorobutadiene to potentially exposed workers.  

Acute Health Effects of Hexachlorobutadiene
The following acute (short-term) health effects may occur immediately or shortly after exposure to Hexachlorobutadiene:
* Contact can irritate and burn the skin and eyes with possible
eye damage.
* Breathing Hexachlorobutadiene can irritate the nose and
* Exposure to Hexachlorobutadiene can cause headache,
dizziness, tremors and even a coma.

Chronic Health Effects 
The following chronic (long-term) health effects can occur at some time after exposure to Hexachlorobutadiene and can last for months or years:

Cancer Hazard
* Hexachlorobutadiene may be a CARCINOGEN in humans since it has been shown to cause kidney cancer in animals.
* Many scientists believe there is no safe level of exposure to a carcinogen. 

Reproductive Hazard
* There is limited evidence that Hexachlorobutadiene is a teratogen in animals. 
Until further testing has been done, it should be treated as a possible teratogen in humans.
* Hexachlorobutadiene may damage the testes and decrease the sperm count in animals. 

Other Long-Term Effects
* Hexachlorobutadiene can irritate the lungs. 
Repeated exposure may cause bronchitis to develop with cough, phlegm, and/or shortness of breath.
* Hexachlorobutadiene may damage the liver and kidneys.

Hazard(s) identification of Hexachlorobutadiene
Classification of the substance or mixture
Acute Tox. 3 H301 Toxic if swallowed.
Acute Tox. 2 H310 Fatal in contact with skin.

Carc. 2 H351 Suspected of causing cancer.
Skin Irrit. 2 H315 Causes skin irritation.
Flam. Liq. 4 H227 Combustible liquid.
Label elements
· GHS label elements The substance is classified and labeled according to the Globally Harmonized System (GHS).

Hazard-determining components of labeling:
· Hazard statements
Combustible liquid.
Toxic if swallowed.
Fatal in contact with skin.
Causes skin irritation.
Suspected of causing cancer.

· Precautionary statements
Obtain special instructions before use.
Do not handle until all safety precautions have been read and understood.
Keep away from flames and hot surfaces. – No smoking.
Do not get in eyes, on skin, or on clothing.
Wash thoroughly after handling.
Do not eat, drink or smoke when using this product.
Wear protective gloves/protective clothing/eye protection/face protection.

If swallowed: Immediately call a poison center/doctor.
Specific treatment (see on this label).
Rinse mouth.
If on skin: Wash with plenty of water.
IF exposed or concerned: Get medical advice/attention.
Take off immediately all contaminated clothing and wash it before reuse.

If skin irritation occurs: Get medical advice/attention.
In case of fire: Use for extinction: CO2, powder or water spray.
Store in a well-ventilated place. Keep cool.
Store locked up.
Dispose of contents/container in accordance with local/regional/national/international regulations.

First-aid measures of Hexachlorobutadiene
General information:
Immediately remove any clothing soiled by the product.
In case of irregular breathing or respiratory arrest provide artificial respiration.
· After inhalation: In case of unconsciousness place patient stably in side position for transportation.
· After skin contact: Immediately wash with water and soap and rinse thoroughly.
· After eye contact: Rinse opened eye for several minutes under running water. Then consult a doctor.

· After swallowing: Do not induce vomiting; immediately call for medical help.
· Information for doctor:
· Most important symptoms and effects, both acute and delayed No further relevant information available.
· Indication of any immediate medical attention and special treatment needed
No further relevant information available.

Fire-fighting measures of Hexachlorobutadiene
Extinguishing media
· Suitable extinguishing agents: Use fire fighting measures that suit the environment.
· Special hazards arising from the substance or mixture No further relevant information available.
· Advice for firefighters
· Protective equipment: No special measures required.

Accidental release measures of Hexachlorobutadiene
Personal precautions, protective equipment and emergency procedures
Wear protective equipment. Keep unprotected persons away.
· Environmental precautions: Do not allow to enter sewers/ surface or ground water.
· Methods and material for containment and cleaning up:
Absorb with liquid-binding material (sand, diatomite, acid binders, universal binders, sawdust).
Dispose contaminated material as waste according to item 13.
Ensure adequate ventilation.

Handling and storage of Hexachlorobutadiene
· Precautions for safe handling Open and handle receptacle with care.
· Information about protection against explosions and fires:
Keep ignition sources away - Do not smoke.
Keep respiratory protective device available.

· Conditions for safe storage, including any incompatibilities
· Storage:
· Requirements to be met by storerooms and receptacles: No special requirements.
· Information about storage in one common storage facility: Not required.
· Further information about storage conditions: Keep receptacle tightly sealed.
· Specific end use(s) No further relevant information available.

Exposure controls/personal protection of Hexachlorobutadiene
Exposure controls
· Personal protective equipment:
· General protective and hygienic measures:
Keep away from foodstuffs, beverages and feed.
Immediately remove all soiled and contaminated clothing.

Wash hands before breaks and at the end of work.
Store protective clothing separately.
Avoid contact with the skin.
Avoid contact with the eyes and skin.

· Breathing equipment:
When used as intended with Agilent instruments, the use of the product under normal laboratory conditions and
with standard practices does not result in significant airborne exposures and therefore respiratory protection is not needed.
Under an emergency condition where a respirator is deemed necessary, use a NIOSH or equivalent approved device/equipment with appropriate organic or acid gas cartridge.

Protection of hands:
Although not recommended for constant contact with the chemicals or for clean-up, nitrile gloves 11-13 mil thickness are recommended for normal use. 
The breakthrough time is 1 hr. 
For cleaning a spill where there is direct contact of the chemical, butyl rubber gloves are recommended 12-15 mil thickness with breakthrough times exceeding 4 hrs. 
Supplier recommendations should be followed.

Material of gloves
For normal use: nitrile rubber, 11-13 mil thickness
For direct contact with the chemical: butyl rubber, 12-15 mil thickness
The selection of the suitable gloves does not only depend on the material, but also on further marks of quality and varies from manufacturer to manufacturer.

Penetration time of glove material
For normal use: nitrile rubber: 1 hour
For direct contact with the chemical: butyl rubber: >4 hours
· Eye protection: Goggles recommended during refilling.

Physical and chemical properties of Hexachlorobutadiene
Form: Fluid
Color: Not determined.
· Odor: Characteristic
· Odor threshold: Not determined
pH-value: Not determined.

Change in condition
Melting point/Melting range: -21 °C (-5.8 °F)
Boiling point/Boiling range: 215 °C (419 °F)

Flash point: ≤93 °C (≤199.4 °F)
· Flammability (solid, gaseous): Not applicable.
· Decomposition temperature: Not determined.
· Auto igniting: Not determined.
· Danger of explosion: Not determined.
· Explosion limits:
Lower: Not determined.
Upper: Not determined.
· Vapor pressure at 20 °C (68 °F): 0.2 hPa (0.2 mm Hg)

Density at 20 °C (68 °F): 1.665 g/cm³ (13.89443 lbs/gal)
· Relative density Not determined.
· Vapor density Not determined.
· Evaporation rate Not determined.
· Solubility in / Miscibility with
Water at 20 °C (68 °F): 0.5 g/l
· Partition coefficient (n-octanol/water): Not determined.

Viscosity of Hexachlorobutadiene
Dynamic: Not determined.
Kinematic: Not determined.
Organic solvents: 100.0 %
VOC content: 100.00 %
1,665.0 g/l / 13.90 lb/gal

Stability and reactivity of Hexachlorobutadiene
Reactivity No further relevant information available.
· Chemical stability
· Thermal decomposition / conditions to be avoided: No decomposition if used according to specifications.
· Possibility of hazardous reactions No dangerous reactions known.
· Conditions to avoid No further relevant information available.
· Incompatible materials: No further relevant information available.
· Hazardous decomposition products: No dangerous decomposition products known.

Hexachlorobutadiene is not reported to occur as a natural product. 
It is chiefly produced as a by-product of the manufacture of chlorinated hydrocarbons where it occurs in the heavy fractions (Hex-waste). 
The world annual production of the compound in heavy fractions was estimated in 1982 to be 10 000 tonnes.
Hexachlorobutadiene can be used for recovery of chlorine-containing gas in chlorine plants and as a wash liquor for removing certain volatile organic compounds from gas streams. 
It has further been used as a fluid in gyroscopes, as heat transfer, transformer, insulating and hydraulic fluids, as a solvent for elastomers, and as an intermediate and fumigant.

The main pathways of entry into the environment are emissions from waste and dispersive use. 
Intercompartmental transport will chiefly occur by volatilization, adsorption to particulate matter, and subsequent deposition or sedimentation. 
Hexachlorobutadiene does not migrate rapidly in soil and accumulates in sediment. 
In water, it is considered persistent unless there is high turbulence.

Hydrolysis does not occur in Hexachlorobutadiene.
The substance seems to be readily biodegradable aerobically, though biodegradability has not been investigated thoroughly. 
Hexachlorobutadiene photolyses on surfaces.
In addition to deposition, reaction with hydroxyl radicals is assumed to be an important sink of hexachlorobutadiene in the troposphere, and the estimated atmospheric half-life is up to 2.3 years.

The substance has a high bioaccumulating potential as has been confirmed by both laboratory and field observations.
Average steady-state bioconcentration factors of 5800 and 17 000, based on wet weight, have been determined experimentally in rainbow trout.
Biomagnification has not been observed either in the laboratory or in the field.

Hexachlorobutadiene has been measured in urban air: in all cases levels were below 0.5 µg/m3. 
Concentrations in remote areas are less than 1 pg/m3. 
In lake and river water in Europe concentrations of up to 2 µg/litre have been recorded, but mean levels are usually below 100 ng/litre. 
In the Great Lakes area of Canada, much lower levels (around 1 ng/litre) were measured. 

Bottom sediment levels here can be as high as 120 µg/kg dry weight of  Hexachlorobutadiene.
Older sediment layers from around 1960 contained higher concen-trations (up to 550 µg/kg wet weight). 
The sediment concentration was demonstrated to increase with particle size in the sediment.

Concentrations of hexachlorobutadiene in aquatic organisms, birds and mammals indicate bioaccumulation but not biomagnification.
In polluted waters, levels of over 1000 µg/kg wet weight have been measured in several species and 120 mg/kg (lipid base) in one species.
Present levels generally remain below 100 µg/kg wet weight away from industrial outflows.

The compound has been detected in human urine, blood and tissues. 
Certain food items containing a high lipid fraction have been found to contain up to about 40 µg/kg and, in one case, over 1000 µg/kg.
One study reported occupational exposures of 1.6-12.2 mg/m3 and urine levels of up to 20 mg/litre.

Hexachlorobutadiene is rapidly absorbed following oral administration to experimental animals, but the rate of absorption following inhalation or dermal exposure has not been investigated.
In rats and mice, the compound distributes mainly to the liver, kidneys and adipose tissue. 
It is rapidly excreted. 
Binding to liver and kidney protein and nucleic acids has been demonstrated.

The biotransformation of the compound in experimental animals appears to be a saturable process. 
This process proceeds mainly through a glutathione-mediated pathway in which hexachlorobutadiene is initially converted to  S-glutathione conjugates. 
These conjugates can be metabolized further, especially in the brush-border membrane of renal tubular cells, to a reactive sulfur metabolite, which probably accounts for the observed nephrotoxicity, genotoxicity and carcinogenicity.

Hexachlorobutadiene (HCBD)
HCBD, Hexaklorbutadien (Hexaklor-1,3-butadien)

Name PRTR : Hexachlorobutadiene (HCBD)
CAS no 87-68-3
Chemical formula C4Cl6
Hexachlorobutadiene (HCBD) is a colourless, almost odourless liquid which main use is as an industrial chemical.

Uses of Hexachlorobutadiene
Hexachlorobutadiene has been used within different industrial applications, such as a solvent in chemical products for textiles, in chlorine production, as an intermediate in rubber production, as a hydraulic fluid and in production of lubricants. 
Hexachlorobutadiene has also been used as a pesticide.

Sources and transportation pathways of Hexachlorobutadiene
Hexachlorobutadiene does not occur naturally in the environment. 
In the past, it has been produced for commercial use in for example Germany, but production has since ceased.
HCBD is also formed unintentionally during production of other chlorinated solvents such as tri- and tetra-chloromethane.
Air is an important transportation pathway. 
If emitted directly to water, hexachlorobutadiene is considered to evaporate to air.

Effects on environment and health of Hexachlorobutadiene
Hexachlorobutadiene is a substance with persistent and bioaccumulative properties. 
The substance is acutely toxic and harmful to aquatic organisms.
Health effects include risk for poisoning by inhalation of fumes and by skin contact with the substance.

International agreements and regulations of Hexachlorobutadiene
Hexachlorobutadiene is regulated by the UN Convention on Long-Range Transboundary Air Pollution (CLRTAP) and the EU Water Framework Directive (2000/60/EC). 
The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on hexachlorobutadiene emissions is made available.

Historically HCBD was used as a solvent for rubber and other polymers, heat transfer fluids, transformer liquid and washing liquor for removing hydrocarbons. 
It has also been used in agriculture as a seed dressing and fungicide for a variety of crops. 
Due to environmental concerns the use of HCBD in such applications has now virtually ceased, although it is possible that HCBD may still be in use in some parts of the world. 
HCBD is still generated as a by-product of tetrachlorethene and tetrachloromethane production. 
HCBD mainly enters the environment during processing: in 1997 EU countries emitted 2 kg of HCBD into the atmosphere and 100 kg into the hydrosphere.

Hexachlorobutadiene has quite a high vapour pressure and is therefore mainly present into the atmosphere (98%), where it has a half-life between 60 days and 1 year. 
In water it has a low solubility of 3,2 mg/l and has a tendency to adsorb to suspended particles and sediments. 
In fact only 0,2 percent of the environmental HCBD is expected to be dissolved in water and the remaining 1,8% adsorbed to sediments and soils. 
In aerobic waters and soils, HCBD can be biodegraded, although its half-life in water is between 30 and 300 days.

Hexachlorobutadiene has a high potential to bioaccumulate. 
High bioaccumulation rates have been shown in a number of marine species, although in others hardly any bioaccumulation took place. 
Some species appear to be more able to metabolise HCBD than others. 
Fish seem to accumulate high levels in their livers, about 10 times more than in other tissues. 

HCBD seems to have a lower tendency to bioaccumulate through food uptake than through direct uptake from water. 
One study which fed predatory fish with contaminated prey fish in fact demonstrated lower concentrations in the predatory fish. 
A study where rats were fed with contaminated food also didn't demonstrate any bioaccumulation. 
Therefore the risks of secondary poisoning for marine mammals and sea birds by biomagnification are doubtful.

Acute toxicity in marine fishes can be caused by concentrations above 0,45 mg/l, in algae by concentrations above 0,85 mg/l. 
Birds fed during 90 days with food containing 10 mg/kg HCBD displayed a reduced fertility, caused by a reduced chick survival.
Measured marine surface water concentrations of HCBD in Europe have reached values of up to 150 ng/l in polluted estuaries, although typical North Sea concentrations are around 4 ng/l. 
The highest concentration measured in fish tissue was 0,4 µg/kg.

Hexachlorobutadiene (HCBD) has the empirical molecular formula C4Cl6. 
HCBD is a non-flammable, incombustible, clear, colourless, oily liquid at room temperature with a mild turpentine-like odour.
The compound is poorly soluble in water, but miscible with ether and ethanol.
The poor solubility in water of HCBD, its high vapour pressure, its high log Koc and log Kow values determine its behaviour and fate in environmental media.
To compare environmental concentrations from various sources and in different media, conversion factors should be used and the following values are recommended : 
1 ppbv of hexachlorobutadiene = 10.67 µg/m3 air, and 1 µg of hexachlorobutadiene per m3
air = 0.094 ppbv at 25 °C and 101.3 kPa (760 mm Hg)

Synonyms for HCBD include 1,1,2,3,4,4-hexachloro-1,3-butadiene, hexachloro-1,3- butadiene, perchlorobutadiene and perchloro-1,3-butadiene. 
Previous common trade names were Dolen-Pur; C-46, UN2279 and GP-40-66:120

During the 1970s and 1980s, large amounts of HCBD were been produced as by-product of chlorination processes involving organic compounds. 
Annual worldwide production of the compound in heavy fractions was estimated to be 10,000 tonnes in 1982 .
Larger quantities of the chemical were reportedly generated in the US as waste by-product from the chlorination of hydrocarbons: about 4,000 tons in 1975 and 14,000 tons in 1982.
In North America (US and Canada), HCBD has never been manufactured as a commercial product. In the US, small quantities of HCBD were imported  mostly from Germany - as commercial product: about 250 tons/year in the late 1970s and 75 tons/year in 1981.

There are no natural sources of HCBD. 
HCBD is generated as a by-product during the production of certain chemicals. 
Most notably, HCBD is found as a contaminant at very low levels in certain chlorinated solvents which are imported and used in Canada. 
As a result, it may be released upon the use of these chemicals. 
Other possible releases of HCBD in the Canadian environment could be from hazardous landfill leachate. 
Long-range transport may also contribute to its presence in the Canadian environment.

When HCBD is released into the environment, it tends to persist in the air, soil or water to which it was released and can accumulate in organisms. 
It can affect the growth and survival of aquatic organisms, notably those found in sediments.
Canadians' exposure to HCBD from environmental sources is less than the Tolerable Intake that Health Canada recommends, which is based on a benchmark dose or effect levels for non-cancer effects in the kidney. 
Tolerable Intake is the level of intake to which it is believed a person may be exposed daily over a lifetime without deleterious effect.

Common Name    : Hexachlorobutadiene
Class    : Small Molecule
Description    : Hexachlorobutadiene is a man-made chemical primarily produced as a by-product in the production of carbon tetrachloride and tetrachloroethene. 
It is also used to make rubber compounds, lubricants, in gyroscopes, as a heat transfer liquid, as a hydraulic fluid, and as a solvent.

Compound Type:
Industrial/Workplace Toxin
Organic Compound
Synthetic Compound

Usage and applications of Hexachlorobutadiene
In 1982, the worldwide production of HCBD was 10’000 tons – but as by-product it exceeded even that. 
In the USA alone 14’000 tons of HCBD were produced in 1981. 
This huge amount of HCBD as by-product gave incentives to find usage of it in the industry. 
This included being used as a solvent for rubber and other polymers, as a “scrubber” for the recovery of chlorine-containing gas or to remove volatile organic components from gas; as hydraulic heat transfer or as a transformer fluid and it was also used in the production of aluminum and graphite rods. 
In addition, it was used primarily in the Soviet Union as an insecticide and fungicide, but less so in Europe.

Some examples of applications:

Hydraulic heat transfer
Transformation fluids
Insecticides and fungicides

First Aid of Hexachlorobutadiene
EYES: First check the victim for contact lenses and remove if present. 
Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. 
Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. 
IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. 
Gently wash all affected skin areas thoroughly with soap and water. 
IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. 
IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas.

INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. 
IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. 
Provide proper respiratory protection to rescuers entering an unknown atmosphere. 
Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing.

Corrosive chemicals will destroy the membranes of the mouth, throat, and esophagus and, in addition, have a high risk of being aspirated into the victim's lungs during vomiting which increases the medical problems. 
If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. 
IMMEDIATELY transport the victim to a hospital. 
If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. 
Transport the victim IMMEDIATELY to a hospital.

OTHER: Since this chemical is a known or suspected carcinogen you should contact a physician for advice regarding the possible long term health effects and potential recommendation for medical monitoring. 
Recommendations from the physician will depend upon the specific compound, its chemical, physical and toxicity properties, the exposure level, length of exposure, and the route of exposure.

Substance identity
EC / List no.: 201-765-5
CAS no.: 87-68-3
Mol. formula: C4Cl6

Hazard classification & labelling of hexachlorobutadiene
Danger! According to the classification provided by companies to ECHA in CLP notifications this substance is fatal in contact with skin, is fatal if inhaled, is toxic if swallowed, is very toxic to aquatic life, is very toxic to aquatic life with long lasting effects, causes serious eye damage, is suspected of causing cancer, may cause damage to organs, causes skin irritation and may cause an allergic skin reaction.

Substances predicted as likely to meet criteria for category 1A or 1B carcinogenicity, mutagenicity, or reproductive toxicity, or with dispersive or diffuse use(s) where predicted likely to meet any classification criterion for health or environmental hazards, or where there is a nanoform soluble in biological and environmental media.
Substances indicated, in 2009, as being intended to be registered by at least one company in the EEA.

Substances for which classification and labeling data have been submitted to ECHA in a registration under REACH or notified by manufacturers or importers under CLP. 
Such notifications are required for hazardous substances, as such or in mixtures, as well as for all substances subject to registration, regardless of their hazard.
Substances listed in the EINECS, ELINCS, or NLP inventories.
Substances whose production and use are banned or severely restricted under the POPs Regulation and/or which are subject to release reduction provisions under the POPs Regulation.

2903 29 00
1,3-Butadiene, 1,1,2,3,4,4-hexachloro-
RCRA waste number U128
C 46
1,3-Butadiene, hexachloro-
NSC 3701
1,3-Butadiene, 1,1,2,3,4,4-hexachloro-, homopolymer
HSDB 2870
Hexachlor-1,3-butadien [Czech]
EINECS 201-765-5
RCRA waste no. U128
BRN 1766570
Butadiene, hexachloro-
4-01-00-00988 (Beilstein Handbook Reference)
Hexachloro-1,3-butadiene, 96%
1, 1,1,2,3,4,4-hexachloro-
UN 2279
Hexachlorobutadiene [UN2279] [Poison]
Hexachloro-1,3-butadiene, analytical standard
Hexachlorobutadiene 5000 microg/mL in Methanol
Hexachloro-1,3-butadiene 10 microg/mL in Methanol
Hexachloro-1,3-butadiene 10 microg/mL in Cyclohexane
Hexachloro-1,3-butadiene 100 microg/mL in Methanol
Hexachloro-1,3-butadiene 100 microg/mL in Cyclohexane
Hexachloro-1,3-butadiene, PESTANAL(R), analytical standard

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