Bromochloromethane or methylene bromochloride and Halon 1011 is a mixed halomethane. It is a heavy low-viscosity liquid with

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, o ...

1.4808. Halon 1011 was invented for use in fire extinguishers in

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

during the mid-1940s, in an attempt to create a less toxic, more effective alternative to

carbon tetrachloride Carbon tetrachloride, also known by many other names (such as tetrachloromethane, also recognised by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting, and Refrigerant-10 in HVACR) is an organic compound with the chemi ...

. This was a concern in aircraft and tanks as carbon tetrachloride produced highly toxic by-products when discharged onto a fire. It was slightly less toxic, and used up until the late 1960s, being officially banned by the NFPA for use in fire extinguishers in 1969, as safer and more effective agents such as halon 1211 and 1301 were developed. Due to its

ozone depletion potential The ozone depletion potential (ODP) of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane (R-11 or CFC-11) being fixed at an ODP of 1.0. Chlorodifluoromethane (R-22), for examp ...

its production was banned from January 1, 2002, at the ''Eleventh Meeting of the Parties for the Montreal Protocol on Substances that Deplete the Ozone Layer''. Aircraft A-20 CBM

Bromochloromethane's biodegradation is catalyzed by the

hydrolase Hydrolase is a class of enzyme that commonly perform as biochemical catalysts that use water to break a chemical bond, which typically results in dividing a larger molecule into smaller molecules. Some common examples of hydrolase enzymes are es ...

enzyme alkylhalidase: :CH₂BrCl + H₂O → CH₂O + HBr + HCl

Preparation

Bromochloromethane is prepared commercially from

dichloromethane Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible wit ...

: :6 CH₂Cl₂ + 3 Br₂ + 2 Al → 6 CH₂BrCl + 2 AlCl₃ :CH₂Cl₂ + HBr → CH₂BrCl + HCl The latter route requires aluminium trichloride as a catalyst. The bromochloromethane is often used as a precursor to methylene bromide.

References

External links

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Notice with Respect to n-Propyl Bromide and Bromochloromethane

Data sheet at albemarle.com
{{halomethanes Halomethanes Fire suppression agents Ozone depletion Organobromides Organochlorides