BACKGROUND OF THE INVENTION 1. Field of the Invention.

The present invention relates to methods for extinguishing fire, preventing fire, and reducing or eliminating the flammability of a flammable working fluid using fluorosulfones.

2. Description of Related Art.

Numerous agents and methods of fire fighting are known and can be selected for a particular fire, depending upon factors such as its size, location and the type of combustible materials involved.

Halogenated hydrocarbon fire fighting 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 aircraft, commercial hand-held extinguishers). 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 the bromine-containing compounds bromotrifluoromethane (CF3Br, Halonm1301) and bromochlorodifluoromethane (CF2CIBr, Halonw1211). These 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 Halo1211 and 1301 production be discontinued.

Thus, there is a need in this field for methods using substitutes or replacements for the commonly-used, bromine-containing fire extinguishing agents. Such substitutes used in such methods should have a low ozone depletion potential ; should have the ability to extinguish, control, and prevent fires, 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 upon use.

Preferably, such substitutes used in such methods 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.

BRIEF SUMMARY OF THE INVENTION The aforementioned objectives of methods using substitutes or replacements for the commonly-used, bromine-containing fire extinguishing agents are met by the present invention which comprises methods for extinguishing fire, preventing fire, and reducing or eliminating the flammability of a flammable working fluid using fluorosulfones.

DETAILED DESCRIPTION OF THE INVENTION The term fluorosulfones is used herein to refer collectively to compounds used in the methods of the present invention. Fluorosulfones useful in the methods of the present invention comprise at least one compound represented by the formula CaHbXcFdS02CpHqXrFs, wherein: X is a halogen independently selected from the group consisting of Cl, Br and) ; a and p are independently selected from integers from 1 to 5, provided that a+p < 7; b and q are independently selected from 0,1, 2, and 3, provided that b+q < 6; c and r are independently selected from 0,1, and 2, provided that c+r < 3; and provided that b+c+d = 2a+1 and q+r+s = 2p+1. Preferably, a is 1,2 or 3; b is 0; and c is 0.

Specific examples of fluorosulfones useful in the methods of the present invention include CF3SO2CF3, CF3SO2CF2CF3, CF3S02CF2CF2CF3, CF3S02CF (CF3) 2, CF3S02CF2CF2CF2CF3, CF3S02C (CF3) 3, CF3S02CF2CF (CF3) 2, CF3S02CF (CF3) CF2CF3, CF3CF2S02CF2CF3, CF3CF2S02CF2CF2CF3, CF3CF2S02CF (CF3) 2, CF3CF2CF2S02CF2CF2CF3, CF3CF2CF2S02CF (CF3) 2, (CF3) 2CFS02CF (CF3) 2, CF3S02CC12CF3, CCIF2CF2S02CF2CCIF2,

CF3SO2CH2CF3, CF3CH2SO2CH (CF3) 2, CHF2SO2CF2CF3, CF3CH2SO2CF2CF3, CHF2SO2CF (CF3) 2, CF3CH2S02CF (CF3) 2, CH3SO2CF3, CH3SO2CF2CF3, CH3SO2CF2CF2CF3, CH3SO2CF (CF3) 2, CH3SO2CF2CF2CF2CF3, CH2CIS02CF3, CH2BrSO2CF3, CH2ISO2CF3, CH2CISO2CCIF2, CH2CISO2CF2CF2CF2CF3, CH2BrSO2CF2CF2CF2CF3, CH2ISO2CF2CF2CF2CF3, CF3SO2CCI2CH3, CH2CICH2SO2CF3, CH2CISO2CF2CF3, CH2BrSO2CF2CF3, CH2lSO2CF2CF3, CH2CISO2CF (CF3) 2, CH2BrSO2CF (CF3) 2, CH2ISO2CF (CF3) 2, CH2CISO2CF2CF2CF3, CH2BrSO2CF2CF2CF3, CH2ISO2CF2CF2CF3, CH2BrCH2S02CF3, CH2CICH2SO2C2F5, CH2BrCH2SO2C2F5, CF3S02CHF2, CF3SO2CCIF2, CF3SO2CBrF2, CF3SO2CF2I, CF3SO2CHCICF3, CF3SO2CHFCBrF2, CF3SO2CHBrCH2Br, CF3S02CCIFCCIF2, <BR> <BR> <BR> <BR> CF3SO2CBrFCBrF2, CF3S02CFICF3, CF3SO2CF2CF21, CF3CF2S02CHF2, CF3CF2SO2CCIF2, CF3CF2SO2CBrF2, CF3CF2SO2CF2I, CF3CF2SO2CHCICF3, CF3CF2SO2CHFCBrF2, CF3CF2SO2CH2CF3, CF3CF2SO2CCI2CF3, CF3CF2SO2CCIFCCIF2, CF3CF2SO2CBrFCBrF2, CF3CF2SO2CFICF3, CF3CF2SO2CF2CF2I, (CF3) 2CFS02CHF2, (CF3) 2CFSO2CCIF2, (CF3) 2CFS02CBrF2, (CF3) 2CFS02CF21, (CF3) 2CFSO2CF2CF3, (CF3) 2CFS02CHCICF3, (CF3) 2CFS02CHFCBrF2, (CF3) 2CFS02CH2CF3, (CF3) 2CFSO2CCI2CF3, (CF3) 2CFS02CCIFCCIF2, (CF3) 2CFSO2CBrFCBrF2, (CF3) 2CFS02CFICF3, and (CF3) 2CFS02CF2CF21.

The aforementioned specific examples of fluorosulfones useful in the methods of the present invention comprise known fluorosulfones as well as the following novel fluorosulfones : (I) CF3SO2CHF2, CF3S02CCIF2, CF3S02CBrF2, CF3SO2CF21, CF3SO2CHCICF3, CF3SO2CHFCBrF2, CF3SO2CCIFCCIF2, CF3SO2CBrFCBrF2, CF3SO2CFICF3, and CF3SO2CF2CF2I are novel fluorosulfones that can be prepared by the reaction of an appropriate sulfonyl fluoride with a source of CF3 anion such as CF3Si (CH3) 3 in the presence of fluoride ion as described by Patel et al. in Inorganic Chemistry, (1992), v. 31, p. 2537; (II) CF3CF2SO2CHF2, CF3CF2SO2CCIF2, CF3CF2SO2CBrF2, CF3CF2SO2CF21, CF3CF2SO2CHCICF3, CF3CF2S02CHFCBrF2, CF3CF2SO2CCI2CF3, CF3CF2SO2CCIFCCIF2, CF3CF2SO2CBrFCBrF2, CF3CF2SO2CFICF3, and CF3CF2SO2CF2CF2I are novel fluorosulfones that can be prepared by the reaction of an appropriate sulfonyl fluoride with tetrafluoroethylene in the presence of fluoride ion in an anhydrous

polar solvent as described by Temple in Journal of Organic Chemistry, (1968), v. 33, p. 344, and French patent application no.

1,555, 130; (III) (CF3) 2CFS02CHF2, (CF3) 2CFS02CCIF2, (CF3) 2CFS02CBrF2, (CF3) 2CFS02CF2i, (CF3) 2CFS02CHCICF3, (CF3) 2CFS02CHFCBrF2, (CF3) 2CFSO2CCI2CF3, (CF3) 2CFSO2CCIFCCIF2, (CF3) 2CFS02CBrFCBrF2, (CF3) 2CFS02CFICF3 and (CF3) 2CFS02CF2CF21 are novel fluorosulfones that can be prepared by reaction of an appropriate sulfonyl fluoride with hexafluoropropene in the presence of fluoride ion in an anhydrous polar solvent as described by Temple in Journal of Organic Chemistry, (1968), v. 33, p. 344, and French patent application no. 1,555, 130; (IV) CF3CF2SO2CF2CF2CF3, CF3S02CF (CF3) CF2CF3, CF3SO2C (CF3) 3, CF3CF2S02CF (CF3) 2, CF3CF2CF2SO2CF (CF3) 2 and (CF3) 2CFS02CF (CF3) 2 are novel fluorosulfones that can be prepared by reacting an appropriate perfluoroalkyl sulfonyl fluoride with a perfluoroolefin in the presence of fluoride ion in an anhydrous polar solvent as described by Temple in Journal of Organic Chemistry, (1968), v. 33, p. 344, and French patent application no.

1,555, 130; (V) CF3S02CF2CF2CF3 is a novel fluorosulfone that can be prepared by the fluorination of known CC13S02CF2CF2CF3 with HF or SbF3/SbCI5 in the liquid phase; (VI) CF3S02CF2CF (CF3) 2 is a novel fluorosulfone that can be prepared using the techniques disclosed by Haszeldine, et. al. in Journai of the Chemical Society, Perkin Transaction 1, (1972), p. 2180, beginning with diisobutyl disulfide and trifluoromethyl iodide. The resulting trifluoromethyl isobutylsulfide can then be oxidized to the sulfone as disclosed by Haszeldine in U. S. Patent No. 3,816, 277, and finally perfluorinated according to the methods of Harmon et al. in Journal of the Chemical Society, Perkin Transaction/, (1979), p. 2675; (VIl) CF3CH2S02CF2CF3, CF3CH2S02CF (CF3) 2, and CH3S02CF2CF3 are novel fluorosulfones that can be prepared by reacting appropriate sulfonyl fluorides with perfluoroolefins in the presence of fluoride ion in an anhydrous polar solvent as described

by Temple in Joumal of Organic Chemistry, (1968), v. 33, p. 344, and French patent application no. 1,555, 130; (VIII) CH3S02CF2CF3 is a novel fluorosulfone that can be prepared by reacting C2F51 with CH3SSCH3 followed by oxidation of the intermediate sulfide using the process described by Haszeldine, et. al. in Journal of the Chemical Society Perkin Trans. I, (1972), p. 159; (IX) CH2CISO2CF2CF3, CH2BrS02CF2CF3, CH21S02CF2CF3, CH2CIS02CF (CF3) 2, CH2BrSO2CF (CF3) 2, CH21S02CF (CF3) 2, CH2CIS02CF2CF2CF3, CH2BrSO2CF2CF2CF3 and CH21SO2CF2CF2CF3 are novel fluorosulfones that can be prepared by reacting a metallated methyl perfluoroalkyl sulfone with chlorine (Cl2), bromine (Br2), or iodine (12). The methyl perfluoroalkyl sulfone can be metallated by reaction with ter-butyl lithium or a Grignard reagent such as methyl magnesium bromide in a solvent such as ether, tetrahydrofuran, dimethoxyethane and diglyme free of compounds containing acidic hydrogen atoms (e. g. , water); (X) CH2BrCH2SO2CF3 and CH2BrCH2SO2C2F5 are novel fluorosulfones that can be prepared by reacting the corresponding ethyl perfluoroalkylsulfones with bromine in the presence of a radical initiator or UV light in a solvent such as carbon tetrachloride ; and (Xl) CH2CICH2SO2C2F5 is a novel fluorosulfone that can be prepared by reacting the ethyl perfluoroethyl sulfone with chlorine in the presence of UV light using a process similar to that described by Laping and Hanack in Tetrahedron Letters, 1979, pages 1309 to 1310.

Fluorosulfones useful in the methods of the present invention can be utilized alone, in combination with one another, or in combination with a co-fire-fighting agent or propellant selected from known fire fighting agents of the classes hydrofluorocarbons, hydrochlorofluorocarbons, perfluorocarbons, perfluoroketones, bromoperfluoroketones, perfluoropolyethers, hydrofluoropolyethers, hydrofluoroethers, chlorofluorocarbons, bromofluorocarbons, bromochlorofluorocarbons, hydrobromocarbons, iodofluorocarbons, and hydrobromofluorocarbons.

Preferred amongst the co-agents are perfluoroketones, bromoperfluorofluoroketones and hydrofluorocarbons. Such co-agents can be chosen to enhance the fire fighting capabilities or modify the

physical properties (e. g. , modify the rate of introduction by serving as a propellant) of a fire fighting composition for a particular type (or size or location) of fire hazard and can preferably be utilized in ratios (of co-agent to fluorosulfone) such that the resulting composition does not form flammable mixtures in air. Such fire fighting mixtures can contain from about 10-90% by weight of at least one fluorosulfone and from about 90- 10% by weight of at least one co-agent.

Fluorosulfones can be utilized additionally in combination with a propellant (e. g. , for expelling a liquid fluorosulfone from a sealed vessel), where the propellant is moderately flammable or flammable, provided that the resultant composition comprising fluorosulfone and such propellant is non-flammable.

Of particular utility are azeotropic and azeotrope-like mixtures containing a fluorosulfone and one or more compounds selected from the group consisting of perfluoroketones, bromoperfluorofluoroketones and hydrofluorocarbons. Such mixtures can provide a fire fighting composition with a lower boiling point than either constituent of the mixture, as well as provide a constant ratio of the components of the mixture during discharge.

Fluorosulfones can be solids, liquids, or gases under ambient conditions, but are preferably utilized for the present methods of fire preventing and extinguishing in either the liquid or the gaseous state (or both). Thus, normally solid compounds are preferably utilized after transformation to liquid and/or gas through melting, sublimation, or dissolution in a liquid co-agent. Such transformation can occur upon exposure of the compound to the heat of a fire.

The present invention includes a method of extinguishing a fire comprising applying to said fire a composition comprising at least one fluorosulfone in an amount sufficient to extinguish said fire.

The extinguishing method of the present invention can be carried out by introducing the composition into an enclosed area surrounding a fire. Any of the known methods of introduction can be utilized provided that appropriate quantities of the composition are metered into the enclosed area at appropriate intervals. For example, a composition can be introduced by streaming, e. g. , using conventional portable (or fixed) fire extinguishing equipment; by misting; or by flooding, e. g. , by releasing (using appropriate piping, valves, and controls) the composition into an enclosed area surrounding a fire. The composition can optionally be

combined with an inert propellant, e. g. , nitrogen, argon, decomposition products of glycidyl azide polymers or carbon dioxide, to increase the rate of discharge of the composition from the streaming or flooding equipment utilized. When the composition is to be introduced by streaming or local application, fluorosulfones having normal boiling points in the range of from about 40°C to about 130°C (especially fluorosulfones that are liquid under ambient conditions) are preferably utilized. When the composition is to be introduced by misting, fluorosulfones having boiling points in the range of from about 40°C to about 110°C are generally preferred. And, when the composition is to be introduced by flooding, fluorosulfones having boiling points in the range of from about 40°C to about 80°C are generally preferred.

The extinguishing process of the present invention comprises introducing at least one fluorosulfone to a fire or flame in an amount sufficient to extinguish the fire or flame. One of ordinary skill in this field will recognize that the amount of fluorosulfone needed to extinguish a particular fire will depend upon the nature and extent of the hazard. When the fluorosulfone is to be introduced by flooding, cup burner test data is useful in determining the amount or concentration of fluorosulfone required to extinguish a particular type and size of fire. The amount of fluorosulfone used to extinguish fire is generally an average resulting concentration of between about 1 and about 10 percent by gas volume of fluorosulfone.

The present invention further includes a method for preventing fire in an air-containing enclosed area containing combustible materials comprising introducing into said area a composition comprising at least one fluorosulfone, and maintaining said composition in an amount sufficient to suppress combustion of combustible materials in said enclosed area.

Thus, the present invention further includes a method of using fluorosulfones for preventing a combustible material from igniting. The present method using fluorosulfones can prevent fires or deflagration in an air-containing, enclosed area that contains combustible materials of the self-sustaining or non-self-sustaining type. This method comprises the step of introducing into an air-containing enclosed area, a non-flammable fire preventing composition that is essentially gaseous comprising at least one fluorosulfone, the composition being introduced and maintained in an

amount sufficient to prevent combustion of combustible materials in the enclosed area.

For fire prevention, fluorosulfones (and any co-agent (s) utilized) can be chosen so as to provide a composition that is essentially gaseous under use conditions. Preferred fluorosulfones for this method have normal boiling points in the range of from about 40°C to about 130°C. The fluorosulfone composition is introduced and maintained in an amount sufficient to prevent combustion of combustible materials in the enclosed area. The amount varies with the combustibility of the particular flammable materials present in the enclosed area. Combustibility varies according to chemical composition and according to physical properties such as surface area relative to volume, porosity, etc. Fluorosulfones can be used to eliminate the combustion-sustaining properties of air and to thereby prevent the combustion of flammable materials (e. g. , paper, cloth, wood, flammable liquids, and plastic items). Fluorosulfones can be maintained continuously if a threat of fire is always present or can be introduced into an atmosphere as an emergency measure if a threat of fire or deflagration develops.

The present invention further includes a method of reducing or eliminating the flammability of a flammable working fluid, comprising: a) providing an additive comprising at least one fluorosulfone, and b) mixing between about 0.1 to about 99 percent by weight of said additive with said flammable working fluid.

Flammable working fluids can comprise refrigerants (e. g. , propane, propylene, difluoromethane (HFC-32), 1, 1-difluoroethane (HFC-152a), 1,1, 1-trifluoroethane (HFC-143a) ), foam blowing agents (e. g., cyclopentane, n-pentane, iso-pentane, n-butane, iso-butane, dimethyl ether, 1, 1-difluoroethane (HFC-152a), 1, 1-dichloro-1-fluoroethane (HCFC- 141b)), solvents (e. g., monochlorotoluenes, benzotrifluorides, volatile methyl siloxane, terpenes, alcohols, petroleum distillates, hydrocarbons, ethers, esters, ketones), aerosol propellants (e. g., dimethyl ether, 1,1- difluoroethane (HFC-152a)), and/or sterilants (e. g. , hydrocarbon epoxides (ethylene oxide) ).

This further method of the present invention uses fluorosulfones as additives to reduce or eliminate the flammability of normally flammable working fluids.

The amount of fluorosulfone needed will depend on the application, the material whose flammability is to be reduced, and the specific

fluorosulfone. Fluorosulfones will be most useful at concentrations ranging from 1-80% by weight, although the concentration of fluorosulfone in the mixtures can range from 0.1-99% by weight. Expedient proportions include 5-40% by weight of fluorosulfone for refrigerant mixtures, 5-50% by weight of fluorosulfone for foam blowing agent mixtures, 1-99% fluorosulfone for solvent mixtures, 5-25% by weight fluorosulfone for aerosol propellant mixtures, and 5-40% by weight fluorosulfone for sterilant mixtures.

Refrigerants, foam blowing agents, solvents, aerosol propellants, and/or sterilants can be either gases (vapors) or liquids. In many cases, materials are stored in one form and used in another. For example, foam blowing agents can be stored as a liquid and used as a gas when the foam is actually blown. In some cases, both gaseous and liquid forms are present during use. Refrigerants are present in both vapor and liquid forms during the operation of most refrigerators or heat pumps. In the gas phase, normally flammable refrigerants, foam blowing agents, solvents, aerosol propellants, and/or sterilants containing the flammability reducing fluorosulfone will have a reduced flammability due to the presence of the fluorosulfone. Of particular importance is the action of the fluorosulfone when the refrigerant, foam blowing agent, solvent, aerosol propellant, and/or sterilant is in the liquid state. Fluorosulfones are volatile, though some are more-so and some less-so. Thus, normally flammable liquid refrigerants, foam blowing agents, solvents, aerosol propellants, and sterilants containing these fluorosulfones will, upon full or partial evaporation, produce vapors that have lower flammabilities due to the presence of the flammability reducing fluorosulfones, which also evaporate. Of particular importance is that release of the fluorosulfones when refrigerants, foam blowing agents, solvents, aerosol propellants, and refrigerants evaporate or are otherwise released into an area, will aid in reducing flammability of the vapor above the liquid/vapor interface (i. e., combustible liquids) and explosivity of the vapor if released into a volume such as a room.

EXAMPLES EXAMPLE 1-FIRE EXTINGUISHING CONCENTRATION OF CF CFgSOgCF2CF3

The fire extinguishing concentration of CF3CF2SO2CF2CF3 is determined by the NFPA Standard Cup Burner method. This method is described in NFPA 2001-2003, Annex B.

Specifically, an air stream is passed at 40 liters/minute through an outer chimney (8.5 cm inner diameter by 53 cm tall) from a glass bead distributor at its base. A fuel cup burner (3.1 cm outer diameter and 2.15 cm inner diameter) is positioned within the chimney at 23.5 cm above the top of the bead distributor. The fire extinguishing agent is added to the air stream prior to its entry into the glass bead distributor while the air flow rate is maintained at 40 liters/minute for all tests. The air and agent flow rates are measured using calibrated rotameters.

The test is conducted by adjusting the fuel (n-heptane) level in the reservoir to bring the liquid fuel level in the cup burner just even with the ground glass lip on the burner cup. With the air flow rate maintained at 40 liters/minute, the fuel in the cup burner is ignited. The fire extinguishing agent is added in measured increments until the flame is extinguished.

The fire extinguishing concentration is determined by thermal conductivity gas chromatography. A sample of the air is taken from the chimney in a gas-tight syringe and injected into the gas chromatograph that is calibrated for the agent.

TABLE 1 FIRE EXTINGUISHING AGENT FIRE EXTINGUISHING CONCENTRATION (volume % in air) EXAMPLE CF3CF2SO2CF2CF3 5. 9 COMPARATIVE CF3CHFCF3 (HFC-227ea) 7. 3 CF3CHFCHF2 (HFC-236ea) 10.2 CF3CF2CH2CI (HCFC-235cb) 6. 2 CF4 20. 5 C2F6 8. 7 CF3Br (Halon-1301) 4. 2 CF2CIBr (Halon 1211) 6. 2 CHF2CI 13. 6