View source for Bromochlorodifluoromethane

{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 443429177
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageFileL1 = Halon-1211-2D.png
| ImageSizeL1 = 112px
| ImageClassL1 = skin-invert
| ImageFileR1 = Halon-1211-3D-vdW.png
| ImageSizeR1 = 120px
| PIN = Bromo(chloro)difluoromethane <!-- Parentheses are used according to Subsection P-16.5.1.3 of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) -->
| OtherNames = Bromochlorodifluoromethane<br />Halon 1211<br />Halon 1211 BCF<br />BCF<br />Freon 12B1
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 9248
| SMILES = BrC(Cl)(F)F
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/CBrClF2/c2-1(3,4)5
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = MEXUFEQDCXZEON-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 353-59-3
| EINECS = 206-537-9
| PubChem = 9625
| ChEBI_Ref = {{ebicite|changed|EBI}}
| ChEBI = 84698
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 91I5X8AJXS
| InChI = 1/CBrClF2/c2-1(3,4)5
  }}
|Section2={{Chembox Properties
| Formula = CBrClF<sub>2</sub>
| MolarMass = 165.36 g/mol
| Appearance = Colorless gas
| Density = 7,1362 kg·m<sup>−3</sup> (15 °C, 1 bar)
| MeltingPtC = −159.5
| MeltingPt_notes = 
| BoilingPtC = −3.7
| BoilingPt_notes = 
| Solubility =
  }}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt = 
 }}
}}

'''Bromochlorodifluoromethane''' ('''BCF'''), also referred to by the code numbers '''Halon 1211''' and '''[[Freon]] 12B1''', is a [[haloalkane]] with the chemical formula [[carbon|C]][[fluorine|F]]<sub>2</sub>[[chlorine|Cl]][[bromine|Br]].  It is used for fire suppression, especially for expensive equipment or items that could be damaged by the residue from other types of extinguishers.<ref name=Ullmann>{{ Ullmann | last1= Dagani|first1=M. J. | last2= Barda|first2=H. J. | last3= Benya|first3=T. J. | last4= Sanders|first4=D. C. | title = Bromine Compounds | doi = 10.1002/14356007.a04_405 }}</ref> It is stored as a liquid under pressure and vaporizes when discharged to suppress fires.<ref>{{cite web|url=https://www.protectionrt.com/the-halon-advantage/|title=The Halon Advantage|date=14 September 2015 }}</ref>
The use of halons, including Halon 1211, has decreased over time due to their adverse impact on the ozone layer. Alternatives have been developed to mitigate environmental concerns while still providing effective fire suppression capabilities.
==Use as a fire extinguishing agent==
Brominated haloalkanes were first used during World War II in [[fire extinguisher]]s for aircraft and [[tank]]s. BCF was introduced as an effective [[gaseous fire suppression]] agent in the mid-1960s for use around highly valuable materials in places such as [[museum]]s, [[Mainframe computer|mainframe]] rooms, and telecommunication [[telephone exchange|switching centers]]. BCFs were also widely used in the maritime industries in the engine rooms of ships and also in the transport industry in vehicles. Its efficiency as a fire extinguishing agent has also led it to be the predominant choice of fire extinguishing agent on commercial aircraft and is typically found in cylindrical hand-held canisters. Its advantages as a fire extinguishing agent are that it has lower toxicity than chemicals such as [[carbon tetrachloride]] and that since it is a [[Covalent bond|covalently bonded compound]], it does not form conductive ions, therefore being usable on electrical equipment.

BCF is an excellent fire extinguishing agent, as it is a streaming agent with low toxicity, a low pressure, liquefied gas, and effective on all common [[Fire class|types of fires]], A, B, and C.<ref>{{cite book|first=George H.|last=Tryon| collaboration=others |title=Fire Protection Handbook Thirteenth Edition 1969|publisher=National Fire Protection Association|location= Boston Massachusetts|year=1969| lccn = 62-12655}}</ref><ref>{{cite book|first=Arthur E.|last=Cote|collaboration=others|title=Fire Protection Handbook Eighteenth Edition|publisher=National Fire Protection Association|location= Quincy, Massachusetts|year= 1997|isbn=0-87765-377-1}}</ref> It is mainly used in portable and wheeled extinguishers, and small spot protection units for aviation and marine engine applications, and was never widely used in fixed systems like [[Bromotrifluoromethane|Halon 1301]] was.

BCF has fairly low toxicity. The lethal concentration for 15 minute exposure is about 32%.<ref name="wiley1"/>

==Synthesis==
BCF is commercially synthesized in a two-step process from [[chloroform]].  Chloroform is [[fluorinated]] with [[hydrogen fluoride]]. The resulting [[chlorodifluoromethane]] is then reacted with elemental [[bromine]] at 400-600&nbsp;°C, with reaction time limited to about 3 seconds. The overall yield is over 90%.<ref name="wiley1">{{cite book | doi = 10.1002/047084289X.rn00562| title = Bromochlorodifluoromethane| work= Encyclopedia of Reagents for Organic Synthesis| year = 2005| last1 = Rozen| first1 = Shlomo| last2 = Hagooly| first2 = Aviv| isbn = 0471936235}}</ref>

===Regulation===
The production of BCF and similar [[chlorofluorocarbon]]s has been [[Ban (law)|banned]] in most countries since January 1, 1994 as part of the [[Montreal Protocol]] on [[Ozone depletion|ozone depleting]] substances. Halon 1211 is also a potent greenhouse gas with a 100-year [[global warming potential]] 2,070 times that of carbon dioxide and an [[atmospheric lifetime]] of 16.0 years.<ref name="Updated">{{cite journal|last1=Hodnebrog|first1=Øivind|last2=Åmås|first2=Borgar|last3=Fuglestvedt|first3=Jan|last4=Marston|first4=George|last5=Myhre|first5=Gunnar|last6= Nielsen|first6=Claus Jørgen|last7=Sandstad|first7=Marit|last8=Shine|first8=Keith P.|last9=Wallington|first9=Tim J.|title=Updated Global Warming Potentials and Radiative Efficiencies of Halocarbons and Other Weak Atmospheric Absorbers|journal=Reviews of Geophysics|date=July 9, 2020|volume=58|issue=3|pages=e2019RG000691 |doi=10.1029/2019RG000691 |pmid=33015672 |pmc=7518032 |bibcode=2020RvGeo..5800691H }}</ref>

Recycling of Halon 1211 allows it to remain in use,<ref>{{cite web|url=http://www.h3rcleanagents.com/support_faq_2.htm|title=Basic Facts about Halon|archiveurl=https://web.archive.org/web/20120104043750/http://www.h3rcleanagents.com/support_faq_2.htm |archivedate=2012-01-04 |publisher=H3R Clean Agents}}</ref><ref>{{cite web|url=http://www.h3rcleanagents.com/support_faq_9.htm|title=Recycling Halon|archiveurl=https://web.archive.org/web/20200809201759/https://www.h3rcleanagents.com/support_faq_9.htm |archivedate=2020-08-09|publisher=H3R Clean Agents}}</ref> although parts availability is limited to a few manufacturers and can be an issue. Halon 1211 is still widely used in the United States, despite its high cost, with the US military being the biggest user. Europe and Australia have banned its use for all but "critical applications" such as aviation, military, and police use. The manufacture of [[Underwriters' Laboratories|UL Listed]] halon 1211 extinguishers was supposed to cease in October 2009.  The future listing is still in discussion. [[Halotron I]], the replacement extinguishing agent, requires a larger volume to get the same ratings as 1211.

==Gallery==
<gallery>

File:H-1211 mm.png|H-1211 measured by the Advanced Global Atmospheric Gases Experiment ([http://agage.mit.edu/ AGAGE]) in the lower atmosphere ([[troposphere]]) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in [[Parts-per notation|parts-per-trillion]].
File:Halon 1211 Fire Extinguisher.jpg|Halon 1211 Fire Extinguisher, USA, early 1990s.
File:Aviation H3R Halon 1211 fire extinguisher.jpg|A portable aviation Halon 1211 fire extinguisher, USA, 2015.
</gallery>

==See also==
*[[Bromochlorofluoromethane]]
*[[Bromotrifluoromethane]]
*[[Ozone depletion potential]]

==References==
{{reflist}}

==External links==
*{{ICSC|0635|06}}
*{{INRS|title=Bromochlorodifluorométhane|number=165|year=1988}}
*[https://www.h3raviation.com/pages/faq Aviation fire extinguisher requirements]

{{Halomethanes}}

[[Category:Halomethanes]]
[[Category:Fire suppression agents]]
[[Category:Greenhouse gases]]
[[Category:Aviation safety]]
[[Category:Organobromides]]
[[Category:Organochlorides]]
[[Category:Organofluorides]]
[[Category:Ozone-depleting chemical substances]]