Compositions – Fire-extinguishing
Reexamination Certificate
2000-07-19
2002-11-12
Toomer, Cephia D. (Department: 1714)
Compositions
Fire-extinguishing
C169S046000, C169S047000
Reexamination Certificate
active
06478979
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to fire extinguishing compositions comprising at least one fluorinated ketone compound and to processes for extinguishing, controlling, or preventing fires using such compositions, for making alpha-branched fluorinated ketones, and for purifying such ketones.
BACKGROUND OF THE INVENTION
Various different agents and methods of fire extinguishing are known and can be selected for a particular fire, depending upon its size and location, the type of combustible materials involved, etc. Halogenated hydrocarbon fire extinguishing agents have traditionally been utilized in flooding applications protecting fixed enclosures (e.g., computer rooms, storage vaults, telecommunications switching gear rooms, libraries, document archives, petroleum pipeline pumping stations, and the like), or in streaming applications requiring rapid extinguishing (e.g., military flight lines, commercial hand-held extinguishers, or fixed system local application). Such extinguishing agents are not only effective but, unlike water, also function as “clean extinguishing agents,” causing little, if any, damage to the enclosure or its contents.
The most commonly-used halogenated hydrocarbon extinguishing agents have been bromine-containing compounds, e.g., bromotrifluoromethane (CF
3
Br, Halon™ 1301) and bromochlorodifluoromethane (CF
2
ClBr, Halon™ 1211). Such bromine-containing halocarbons are highly effective in extinguishing fires and can be dispensed either from portable streaming equipment or from an automatic room flooding system activated either manually or by some method of fire detection. However, these compounds have been linked to ozone depletion. The Montreal Protocol and its attendant amendments have mandated that Halon™ 1211 and 1301 production be discontinued (see, e.g., P. S. Zurer, “Looming Ban on Production of CFCs, Halons Spurs Switch to Substitutes,”
Chemical & Engineering News
, page 12, Nov. 15, 1993).
Thus, there has developed a need in the art for substitutes or replacements for the commonly-used, bromine-containing fire extinguishing agents. Such substitutes should have a low ozone depletion potential; should have the ability to extinguish, control, or prevent fires or flames, e.g., Class A (trash, wood, or paper), Class B (flammable liquids or greases), and/or Class C (electrical equipment) fires; and should be “clean extinguishing agents,” i.e., be electrically non-conducting, volatile or gaseous, and leave no residue. Preferably, substitutes will also be low in toxicity, not form flammable mixtures in air, have acceptable thermal and chemical stability for use in extinguishing applications, and have short atmospheric lifetimes and low global warming potentials. The urgency to replace bromofluorocarbon fire extinguishing compositions is especially strong in the U.S. military (see, e.g., S. O. Andersen et al., “Halons, Stratospheric Ozone and the U.S. Air Force,”
The Military Engineer
, Vol. 80, No. 523, pp. 485-492, August, 1988). This urgency has continued throughout the 1990s (see
US Navy Halon
1211
Replacement Plan Part
1
—Development of Halon
1211
Alternatives
, Naval Research Lab, Washington, D.C., Nov. 1, 1999).
Various different fluorinated hydrocarbons have been suggested for use as fire extinguishing agents. However, to date, we are unaware that any fluorinated ketone having zero, one, or two hydrogen atoms on the carbon backbone has been evaluated as a fire-fighting composition.
SUMMARY OF THE INVENTION
In one aspect, this invention provides a process for controlling or extinguishing fires. The process comprises introducing to a fire or flame (e.g., by streaming or by flooding) a non-flammable extinguishing composition comprising at least one fluorinated ketone compound containing up to two hydrogen atoms. Preferably, the extinguishing composition is introduced in an amount sufficient to extinguish the fire or flame. The fluorinated ketone compound can optionally contain one or more catenated (i.e., “in-chain”) oxygen, nitrogen or sulfur heteroatoms and preferably has a boiling point in the range of from about 0° C. to about 150° C.
The fluorinated ketone compounds used in the process of the invention are surprisingly effective in extinguishing fires or flames while leaving no residue (i.e., function as clean extinguishing agents). The compounds can be low in toxicity and flammability, have no or very low ozone depletion potentials, and have short atmospheric lifetimes and low global warming potentials relative to bromofluorocarbons, bromochlorofluorocarbons, and many substitutes therefor (e.g., hydrochlorofluorocarbons, hydrofluorocarbons, and perfluorocarbons). Since the compounds exhibit good extinguishing capabilities and are also environmentally acceptable, they satisfy the need for substitutes or replacements for the commonly-used bromine-containing fire extinguishing agents which have been linked to the destruction of the earth's ozone layer.
In other aspects, this invention also provides an extinguishing composition and a process for preventing fires in enclosed areas.
The present invention also provides novel fluoroketones of the formula (CF
3
)
2
CFC(O)CF
2
Cl and CF
3
OCF
2
CF
2
C(O)CF(CF
3
)
2
and fire extinguishing compositions which include such novel fluoroketones in amounts sufficient to extinguish a fire.
The present invention also provides a process for reacting an acyl halide with hexafluoropropylene to make a fluorinated ketone having a minimal amount of dimer and trimer by-products.
The present invention further provides a process for removing undesired dimeric and/or trimeric by-products formed in the preparation of a fluorinated ketone prepared by the reaction of hexafluoropropylene with an acyl halide in the presence of fluoride ion where the reaction product, i.e., the fluorinated ketone, is treated with an alkali permanganate salt, e.g. potassium permanganate, in a suitable solvent.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION
Compounds that can be utilized in the processes and composition of the invention are fluorinated ketone compounds. The compounds of this invention can be utilized alone, in combination with one another, or in combination with other known extinguishing agents (e.g., hydrofluorocarbons, hydrochlorofluorocarbons, perfluorocarbons, perfluoropolyethers, hydrofluoropolyethers, hydrofluoroethers, chlorofluorocarbons, bromofluorocarbons, bromochlorofluorocarbons, hydrobromocarbons, iodofluorocarbons, and hydrobromofluorocarbons). The compounds can be solids, liquids, or gases under ambient conditions of temperature and pressure, but are preferably utilized for extinguishing in either the liquid or the vapor state (or both). Thus, normally solid compounds are preferably utilized after transformation to liquid and/or vapor through melting, sublimation, or dissolution in a liquid co-extinguishing agent. Such transformation can occur upon exposure of the compound to the heat of a fire or flame.
Fluorinated ketones useful in this invention are ketones which are fully fluorinated, i.e., all of the hydrogen atoms in the carbon backbone have been replaced with fluorine; or ketones which are fully fluorinated except for one or two hydrogen, chlorine, bromine and/or iodine atoms remaining on the carbon backbone. Fire performance is compromised when too many hydrogen atoms are present on the carbon backbone. For example, a fluorinated ketone with three or more hydrogen atoms on the carbon backbone performs more poorly than a ketone with the same fluorinated carbon backbone but having two, one or zero hydrogen atoms, so that significantly more extinguishing composition of the former is required to extinguish a given fire. The fluoroketones may also include those that contain one or more catenated heteroatoms interrupting the carbon backbone in the perfluorinated portion of the molecule. A catenated heteroatom is, for example, a nitrogen, oxygen or sulfur atom.
Preferably, the majority of halogen atoms attached to the carbon backbone are fluorine; most preferably, all
Behr Fred E.
Costello Michael G.
Flynn Richard M.
Minday Richard M.
Owens John G.
3M Innovative Properties Company
Toomer Cephia D.
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