Chemistry:Bromotrifluoromethane

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Short description: Organic halide used for fire suppression
Bromotrifluoromethane
Bromotrifluoromethane-chemical.png
Halon-1301-3D-vdW.png
Names
Preferred IUPAC name
Bromotri(fluoro)methane
Other names
  • Bromotrifluoromethane
  • Trifluorobromomethane
  • Monobromotrifluoromethane
  • Trifluoromethyl bromide
  • Bromofluoroform
  • Carbon monobromide trifluoride
  • Halon 1301
  • BTM
  • Freon 13BI
  • Freon FE 1301
  • R 13B1
  • Halon 1301 BTM
Identifiers
3D model (JSmol)
ChemSpider
EC Number
  • 200-887-6
RTECS number
  • PA5425000
UNII
UN number 1009
Properties
CBrF3
Molar mass 148.910 g·mol−1
Appearance Colorless gas
Odor Odorless[1]
Density 1.538 g/cm3 (at −58 °C (−72 °F))
Melting point −167.78 °C (−270.00 °F; 105.37 K)
Boiling point −57.75 °C (−71.95 °F; 215.40 K)
0.03 g/L (20 °C (68 °F))
log P 1.86
Vapor pressure 1434 kPa (20 °C (68 °F))
Hazards
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
834,000 ppm (rat, 15 min)[2]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1000 ppm (6100 mg/m3)[1]
REL (Recommended)
 TWA 1000 ppm (6100 mg/m3)[1]
IDLH (Immediate danger)
 40,000 ppm[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Bromotrifluoromethane, commonly referred to by the code numbers Halon 1301, R13B1, Halon 13B1 or BTM, is an organic halide with the chemical formula CBrF3. It is used for gaseous fire suppression as a far less toxic alternative to bromochloromethane.[3]

Table of physical properties

Property Value
Critical temperature (Tc) 66.9 °C (340.08 K)
Critical pressure (pc) 3.956 MPa (39.56 bar)
Critical density (ρc) 5.13 mol.l−1
Ozone depletion potential (ODP) 10 (CCl3F = 1)
Global warming potential (GWP) 6900 (CO2 = 1)

Synthesis

Bromotrifluoromethane is commercially synthesized in a two-step process from chloroform. Chloroform is fluorinated with hydrogen fluoride.[4]

CHCl3 + 3 HF → CHF3 + 3 HCl

The resulting Fluoroform is then reacted with elemental bromine.

CHF3 + Br2 → CF3Br + HBr

Uses

Warning sign for fire suppression system
Civilian Halon 1301 fire extinguisher, USA, 1980s

Halon 1301 was developed in a joint venture between the U.S. Army and Purdue University in the late 1940's,[5] and became a DuPont product in 1954. It was introduced as an effective gaseous fire suppression fixed systems agent in the 1960s, and was used around valuable materials, such as aircraft, mainframe computers, and telecommunication switching centers, usually in total flooding systems.[6] It was also widely used in the maritime industry to add a third level of protection should the main and emergency fire pumps become inoperable or ineffective. Halon 1301 was never widely used in portables outside marine, military and spacecraft applications, due to its limited range, and invisible discharge. It does not produce the characteristic white cloud like CO2 and is difficult to direct when fighting large fires. Halon 1301 is ideal for armored vehicles and spacecraft, because it produces fewer toxic by-products than does Halon 1211, which is critical for combat or space conditions where a compartment may not be able to be ventilated immediately. Halon 1301 is widely used by the U.S. Military[7] and NASA in a 2-3/4 lb portable extinguisher with a sealed, disposable cylinder for quick recharging. Other agents such as CO2 and FE-36 (HFC-236fa) wet chemical are largely replacing halon 1301 for environmental concerns. Civilian models in 2-3/4, 3, and 4 lb sizes were also made.

It is considered good practice to avoid all unnecessary exposure to Halon 1301, and to limit exposures to concentrations of 7% and below to 15 minutes. Exposure to Halon 1301 in the 5% to 7% range produces little, if any, noticeable effect. At levels between 7% and 10%, mild central nervous system effects such as dizziness and tingling in the extremities have been reported.[8] In practice, the operators of many Halon 1301 total flooding systems evacuate the space on impending agent discharge.

Halon systems are among the most effective and commonly used fire protection systems used on commercial aircraft. Halon 1301 is the primary agent used in commercial aviation engine, cargo compartments, and auxiliary power unit fire zones.[9][10] Efforts to find a suitable replacement for Halon 1301 have not produced a widely accepted replacement.[11][12]

Bromotrifluoromethane was also used as a filling of the bubble chamber in the neutrino detector Gargamelle.

Before the dangers of Halon 1301 as an ozone depleter were known, many industrial chillers used it as an efficient refrigerant gas.[13]

H-1301 measured by the Advanced Global Atmospheric Gases Experiment (AGAGE) in the lower atmosphere (troposphere) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion.

Chemical reagent

It is a precursor to trifluoromethyltrimethylsilane, a popular trifluoromethylating reagent in organic synthesis.[14]

Alternatives

Halon 1301 hazard sign, with instructions upon gas discharge.

Alternatives for normally occupied areas include (PFC-410 or CEA-410), C3F8 (PFC-218 or CEA-308), HCFC Blend A (NAF S-III), HFC-23 (FE 13), HFC-227ea (FM 200), IG-01 (argon), IG-55 (argonite), HFC-125, or HFC-134a. For normally unoccupied areas, the alternatives include carbon dioxide, powdered Aerosol C, CF3I, HCFC-22, HCFC-124, HFC-125, HFC-134a, gelled halocarbon/dry chemical suspension (PGA), blend of inert gas, high expansion foam systems and powdered aerosol (FS 0140), and IG-541 (Inergen).[15] Perfluorocarbons, i.e., PFCs such as C3F8, have very long atmospheric lifetimes and very high global warming potentials. Hydrochlorofluorocarbons, i.e., HCFCs including HCFC containing NAF S-III, contain chlorine and are stratospheric ozone layer depleters, although less so than Halon 1301. Their selection for usage as Halon replacements should consider those factors, and is restricted in some countries.

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 NIOSH Pocket Guide to Chemical Hazards. "#0634". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0634.html. 
  2. ↑ "Trifluorobromomethane". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/idlh/75638.html. 
  3. ↑ Dagani, M. J.; Barda, H. J.; Benya, T. J.; Sanders, D. C.. "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a04_405. 
  4. ↑ Brice, T. J.; Pearlson, W. H.; Simons, J. H. (June 1946). "Fluorocarbon Bromides" (in en). Journal of the American Chemical Society 68 (6): 968–969. doi:10.1021/ja01210a017. ISSN 0002-7863. https://pubs.acs.org/doi/abs/10.1021/ja01210a017. 
  5. ↑ "Final Report on Fire Extinguishing Agents for the Period September 1, 1947, to June 30, 1950", Contract No. W44-099eng-507, Purdue Research Foundation, Lafayette, Indiana, July 1950.
  6. ↑ NFPA 12A Standard on Halon 1301 Fire Extinguishing Systems https://www.nfpa.org/codes-and-standards/1/2/a/12a?l=125
  7. ↑ Hodges and McCormick, "Fire Extinguishing Agents for Protection of Occupied Spaces in Military Ground Vehicles," 2010, DTIC ADA517470 https://apps.dtic.mil/sti/citations/ADA517470
  8. ↑ NFPA 12A Standard on Halon 1301 Fire Extinguishing Systems, 2004 Edition / Annex D, Hazards to Personnel, section D.2.2
  9. ↑ United States Environmental Protection Agency | Guidance for the EPA Halon(R) Emission Reduction Rule | Federal Aviation Administration
  10. ↑ Boeing Commercial Aeromagazine | Quarter 04, 2011 | Replacing Halon in Fire Protection Systems: a Progress report
  11. ↑ Aerospace Manufacturing and Design | Halon Alternatives for Aircraft Propulsion Systems consortium formed | January 27, 2015
  12. ↑ FAA | Task Group on Halon Options
  13. ↑ "National Refrigerants MSDS". http://www.refrigerants.com/msds/r13b1.pdf. 
  14. ↑ Ramaiah, Pichika; Krishnamurti, Ramesh; Prakash, G. K. Surya (1995). "1-Trifluoromethyl-1-cyclhexanol". Org. Synth. 72: 232. doi:10.15227/orgsyn.072.0232. 
  15. ↑ Halon 1301 Replacements

External links



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