BROMOTRIFLUOROMETHANE

Description

Bromotrifluoromethane (CBrF3) is a colorless, odorless gas that, under the name Halon 1301 and others, primarily was used as a fire suppressant. It and other bromofluorocarbons were synthesized in 1946 by T. J. Brice, W. H. Pearlson, and J. H. Simons at Penn State, then known as Pennsylvania State College. Their general method was to heat hydrogen-containing fluorocarbons with molecular bromine at 40–50 °C.
Halon 1301 and other halocarbons were used instead of water and aqueous solutions to combat fires in locations where valuable items such as computers and museum pieces would ?be harmed by water damage. Its extreme health hazards (see the hazard information table) mandated limited human exposure .
In addition to its use as a fire suppressant, CBrF3 was used as a refrigerant; it is also a precursor to the trifluoromethylating agent trifluoromethyltrimethylsilane, the Molecule of the Week for April 12, 2021. CBrF3, however, is an atmospheric ozone-depleting agent; when the Montreal Protocol was instituted in 1989, it and other Halon fire suppressants and refrigerants had to be replaced.
One CBrF3 replacement is 1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)pentan-3-one1, which, under the name Novec 1230, is a liquid (bp 49 °C) fire suppressant. As with CBrF3, it is used to avoid damage to items of value. A purer form of this molecule, Novec 649, is marketed as a low-temperature heat-transfer fluid.
1. CAS Reg. No. 756-13-8.

Chemical properties

Trifluorobromomethane is a colorless gas with a slight ethereal odor. Shipped as a liquefied compressed gas.

The Uses of BROMOTRIFLUOROMETHANE

Used as fire extinguishing agent for oil, electrical equipment, organic solvent, natural gas and a variety of organics, especially for important military and civilian sites.

The Uses of BROMOTRIFLUOROMETHANE

Fire extinguishing agent; refrigerant.

Synthesis Reference(s)

Journal of the American Chemical Society, 68, p. 968, 1946 DOI: 10.1021/ja01210a017

General Description

A colorless, odorless gas at room conditions Shipped as a liquid confined under its own vapor pressure. Noncombustible. Nontoxic but can asphyxiate by the displacement of air. Contact with the unconfined liquid can cause frostbite by evaporative cooling. Exposure of the container to prolonged heat or fire can cause BROMOTRIFLUOROMETHANE to rupture violently and rocket.

Air & Water Reactions

Slightly soluble in water.

Reactivity Profile

BROMOTRIFLUOROMETHANE may react with aluminum to produce substantial heat. Other halogenated hydrocarbons, such as fluorotrichloromethane, dichlorodifluoromethane, chlorodifluoromethane, tetrafluoromethane produce sufficient heat in this way to melt aluminum pieces. The vigor of the reaction appears to depend on the degree of fluorination and the vapor pressure [Chem. Eng. News 39(27):44 1961].

Health Hazard

Vapors may cause dizziness or asphyxiation without warning. Vapors from liquefied gas are initially heavier than air and spread along ground. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire may produce irritating, corrosive and/or toxic gases.

Fire Hazard

Some may burn but none ignite readily. Containers may explode when heated. Ruptured cylinders may rocket.

Safety Profile

Wildly toxic by inhalation. Incompatible with aluminum. When heated to decomposition it emits toxic fumes of Fand Br-. See also BROMIDES and FLUORIDES.

Potential Exposure

This material is used as a fire extinguishing agent, a chemical intermediate, and as a refrigerant.

Shipping

UN1009 Bromotrifluoromethane or Refrigerant gas, R-13B, Hazard Class: 2.2; Labels: 2.2-Nonflammable gas. Cylinders must be transported in a secure upright position, in a well-ventilated truck. Protect cylinder and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express written permission of the owner.

Purification Methods

Purify the gas by passing it through a tube containing P2O5 on glass wool into a vacuum system where it is frozen out in a quartz tube and degassed by a cycles of freezing, evacuating and thawing. [Beilstein 1 III 83, 1 IV 73.]

Incompatibilities

Keep away from chemically active metals, such as calcium, powdered aluminum; zinc, magnesium. Attacks some plastics, rubber, and coatings.

Waste Disposal

Return refillable compressed gas cylinders to supplier. Incineration, preferably after mixing with another combustible fuel. Care must be exercised to assure complete combustion to prevent the formation of phosgene. An acid scrubber is necessary to remove the halo acids produced.