Hexachlorobutadiene, Cl2C=C(Cl)C(Cl)=CCl2, is a colorless liquid at room temperature that has an odor similar to that of turpentine. It is a chlorinated aliphatic diene with niche applications but is most commonly used as a solvent for other chlorine-containing compounds.
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.
|Temp (C)||Molar Solubility of HCBD||Molar Solubility of CCl4|
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 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.
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.
Residents Evacuated Near ICI Site.(homes have hexachlorobutadiene concentrations inside)(Brief Article)(Statistical Data Included)
Feb 02, 2000; Eleven families were evacuated last week from Weston, U.K., near ICI's Runcorn complex, after ICI detected concentrations of...