Bromotrifluoromethane

Bromotrifluoromethane

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
CAS Number	75-63-8 Y
3D model (JSmol)	Interactive image
ChemSpider	6144 Y
ECHA InfoCard	100.000.807
EC Number	200-887-6
PubChem CID	6384
RTECS number	PA5425000
UNII	52231LCA7R Y
UN number	1009
CompTox Dashboard (EPA)	DTXSID5026415
InChI InChI=1S/CBrF3/c2-1(3,4)5 Y Key: RJCQBQGAPKAMLL-UHFFFAOYSA-N Y InChI=1/CBrF3/c2-1(3,4)5 Key: RJCQBQGAPKAMLL-UHFFFAOYAV
SMILES BrC(F)(F)F
Properties
Chemical formula	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)
Solubility in water	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):
LCLo (lowest published)	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). Y verify (what is YN ?) 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

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

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]

Chemical reagent

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

Alternatives

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

• Halon 1211
• Fire extinguisher
• Montreal Protocol

References

External links

• International Chemical Safety Card 0837
• NIOSH Pocket Guide to Chemical Hazards. "#0634". National Institute for Occupational Safety and Health (NIOSH).
• "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.
• MSDS sheet at airliquide.com^{[permanent dead link]}
• FAA paper on testing cylinders used to store Halon 1301 without breaking their seals (pdf)
• MSDS for bromotrifluoromethane (pdf)
• Basic Facts about Halon Archived 2012-01-04 at the Wayback Machine