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Bromotrichloromethane (BrCCl3) is practically insoluble in
water, but it is soluble in all proportions in alcohol and ether,
and miscible with many organic liquids. Uncatalyzed addition
of bromotrichloromethane to ethylene can lead to violent
explosion. It is frequently used in organic synthesis and as
a flame retardant. The general population may be exposed to
bromotrichloromethane via ingestion of food and drinking
water. Bromotrichloromethane has been identified as a volatile
compound in both bacon and pork. Production of bromotrichloromethane
has been banned in the United States, and
therefore occupational exposure would only occur when using
BrCCl3 for organic synthesis. The acute lethal dose in humans is
500–5000 mg kg
-1. Inhalation of 20 000 ppm for 60 min will
result in surgical anesthesia and possibly death. Based on
effects in monkeys and rats, this compound may induce coma
and possibly death in humans exposed to 20 000 ppm for
60 min; 10 000 ppm for 30 min will provoke marked incoordination;
2000 ppm for 5 min may produce disturbance of
equilibrium. BrCCl3 exposure to cells can cause destruction of
CYP450 (drug-metabolizing enzymes), making cells resistant
to toxicity. This compound is considered a prolific inducer of
lipid peroxidation as measured by MDA (malondialdehyde
production) and 4-HNE (4-hydroxynonenal concentration).
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Clear colourless to slightly yellow liquid
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Although bromotrichloromethane is no longer produced in the
United States, it is still used in organic syntheses of various
compounds.
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Toxic by ingestion and inhalation of fumes.
Safety Profile
Poison by ingestion and
intraperitoneal routes. Narcotic in high
concentration. Mutation data reported. See
also CHLOROFORM. Incompatible with
ethylene. When heated to decomposition it
emits very toxic fumes of Cland Br-.
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With the loss of bromide ion, mediated by cytochrome P450
enzyme in the liver, the trichlorocarbon free radical is responsible for lipid peroxidation, which is the predominant
mechanism of hepatotoxicity. BrCCl3, when metabolized
in vitro and in vivo, produces phosgene (COCl2) and trichloromethyl
free radicals that ultimately cause massive lipid
peroxidation and depletion of cellular glutathione. Both these
events contribute to toxicity. Activation of membrane phospholipase
A2 has also been considered as another prime
suspect contributing to toxic outcomes. It is also known to
cause cerebellar degeneration in rodents. It is cytotoxic to the
sperm in the testes at the time of exposure. Renal tumors are
induced in male mice due to depletion of glutathione,
increased lipid peroxidation, and DNA lesions.
Purification Methods
Wash it with aqueous NaOH solution or dilute Na2CO3, then with H2O, and dry with CaCl2, BaO, MgSO4 or P2O5 before distilling in diffuse light and storing in the dark. It has also been purified by treatment with charcoal and fractional crystallisation by partial freezing. It is purified also by vigorous stirring with portions of conc H2SO4 until the acid did not discolour during several hours stirring. Wash with Na2CO3 and water, dry with CaCl2 and then illuminate it with a 1000W projection lamp at 15cm for 10hours, after making it 0.01M in bromine. Pass it through a 30 x 1.5cm column of activated alumina and fractionally redistil it through a 12-in Vigreux column (p 11). [Firestone & Willard J Am Chem Soc 83 3511 1961; see also Cadogan & Duell J Chem Soc 4154 1962, Beilstein 1 IV 77.]
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