CA2220431A1 - The use of bis(difluoromethyl)ether as a fire extinguishant - Google Patents
The use of bis(difluoromethyl)ether as a fire extinguishant Download PDFInfo
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- CA2220431A1 CA2220431A1 CA002220431A CA2220431A CA2220431A1 CA 2220431 A1 CA2220431 A1 CA 2220431A1 CA 002220431 A CA002220431 A CA 002220431A CA 2220431 A CA2220431 A CA 2220431A CA 2220431 A1 CA2220431 A1 CA 2220431A1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
- C08J9/14—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent organic
- C08J9/143—Halogen containing compounds
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D1/00—Fire-extinguishing compositions; Use of chemical substances in extinguishing fires
- A62D1/0028—Liquid extinguishing substances
- A62D1/0057—Polyhaloalkanes
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2203/00—Foams characterized by the expanding agent
- C08J2203/14—Saturated hydrocarbons, e.g. butane; Unspecified hydrocarbons
- C08J2203/146—Saturated hydrocarbons containing oxygen and halogen atoms, e.g. F3C-O-CH2-CH3
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Abstract
Bis(difluoromethyl)ether as a fire extinguishant. Bis(difluoromethyl)ether is non-flammable, non-chlorofluorocarbon containing compound having an atmospheric life of only 2,8 years, and has zero ozone depletion potential.
Description
WO 96/4(~371 PCT/US96/08187 l~IE ~SE OF BIS (DIFL~JOROh~ ~ YL.) ETE~ER AS A FIRE ~ J~uls}IANT
R~2L ~K~:~o~7D OF T~IE 11!1 V151!1-1 lON
The Halons, particularly 1301 (CF3Br) and 1211 (CF2ClBr), have been used successfully for many years as fire and explosion suppressants. Halon 1301 is generally used in "total flood" applications in which the agent is discharged from a fixed automated system to uniformly fill a space to extinguish a fire or to provide inertion. The agent concentration required for fire suppression is the most important performance parameter in this application.
Halon 1211 is usually used in "streaming" applications in which the halon is discharged from a portable, m~n~
extinguisher to provide localized fire suppression. Both the extinguishment concentration and the discharge characteristics of "streaming" agents are important in determining fire extinguishment capacity.
The vapor pressure of Halon 1301 is 234 psia, and that of Halon 1211 is 40 psia at room temperature. Either system can be pressurized for faster discharge, if needed.
The Halons contain chlorofluorocarbons, and thus have been subject to the same restraints as other compounds of that class in view of their potential to deplete the ozone. Halon 1211 has an atmospheric life of 15 years and an ozone depletion potential (ODP) of 3Ø Halon 1301 has an atmospheric life of 110 years and an ODP of 10Ø When these compounds are released to the atmosphere, they undergo photolitically catalyzed deomposition and the halogen atoms then catalyze the decomposition of ozone. Suitable substitutes must meet . ~ -WO96/40371 PCT/U',G~V~187 certain re~uirements. There should be hydrogen in the molecule in order to facilitate photolytic degradation in the troposphere, but preferably the molecule should contain no halogen other than fluorine. Acceptab]e substitutes would exhibit fire suppressant efficiency, low residue levels, non-conductivity, negligible ODP, low global warming potential (GWP), non-corrosiveness, materials compatibility, stability under long term storage, and low toxicity.
It is therefore an object of the present invention to provide a fire extinguishant that does not su~fer ~rom the drawbacks of conventional exting~ h~nts.
It is a further object of the present invention to provide a method of extinguishing fires while m;n;m; zing the potential for ozone depletion.
S~MARY OF T~E lN V ~ N
The problems of the prior art have been overcome by the present invention, which provides a non-chlorofluorocarbon compound as a fire extinguishant. More specifically, the present inventor has found that Bis(difluoromethyl)ether is non-flammable, has an atmospheric life o~ only 2,8 years, and has zero ozone depletion potential The ether behaves well as a fire extinguishant.
BRIEF DESCRIPTION OF TEE DRAWING
Figure l is a schematic view o~ apparatus used to test ~ire extinguishing concentrations.
DET~ TT-T~n DESCRIPTION OF TEE lNV~N-l-lON
Bis(difluoromethyl)ether can be prepared by a variety of processes conventional in the art. For example, it can be WO96/40371 PCT/U~ 187 prepared by chlorination of dimethyl ether ~ollowed by isolation and fluorination of bis(dichloromethyl)ether. A
preferred approach avoids the unstable complex mixture o~
chlorinated ethers, some of which are carcinogens, by employing methyl difluoromethyl ether as a starting material. The methyl difluoromethyl ether is chlorinated to give a chlorinated reaction mixture including at least one compound of the formula CF2HOCH3zClz, wherein z is l, 2 or 3, which compound can be readily separated from the chlorinated reaction mixture. The chlorination of methyldifluoromethyl ether would generally form only three derivatives, i.e., z=l, z=2 and z-3. The dichloromethyl difluoromethyl ether (z=2) can be readily separated from the chlorinated reaction mixture and is then fluorinated, with or without such separation, to form the bis(difluoromethyl)ether. The production of CF2HOCCl3 (z=3) can be inhibited, and any produced also may be separated from the chlorination reaction product and fluorinated. Alternatively, the chlorination reaction product itself may be fluorinated (without prior separation) as follows:
CF2HOCH2Cl > CF2HOCH2F (I) _______~ CF2HOCHClF
CF2HOCHCl2 ~ CF2HOCHF2 (II) _, CF2HOCCl2F
CF2HOCCl3 ~ ) CF2HOCClF2 CF2HOCF3 (III) The methyl difluoromethyl ether which is regarded as the starting material for the process of the present invention is a known compound which may be prepared in the m~nn~ reported by Hine and Porter in their aforementioned article published in the Journal of the American Chemical Society. Specifically, r difluoromethyl methyl ether is produced by reaction of sodium methoxide (NaOMe) with chlorodifluoromethane (CF2HCl), which reaction may be represented as follows:
CF2HCl + CH30Na -----------~ CF2HOCH3 + NaCl Briefly, the method involves forming an alcohol solution of sodium methoxide and bubbling the chlorodi~luoromethane slowly into the reaction mixture to obtain the wethyldi~luoromethyl ether as a residue in the reaction mixture. Some product is entrained with unreacted CF2HCl and can be separated from it in a distillation operation.
The starting ether, CHF20CH3, also m:ight be prepared by first reacting NaOH with CH30H, in ef~ect making CH30Na, and then reacting it with CF2HCl. However, water is also formed in the NaOH/C~OH reaction. The effect water has on the subsequent reaction to form CHF20CH3 is to reduce the yield of CHF20CH3 .
The chlorination and fluorination steps of this invention can be represented as follows:
zCl2 CHF2OCH3 ----------~ CF2HOCH3zClz + zHCl (wherein z = 1,2,or 3) F
CF2HOCH3 zClz - - - - - - - ---- - ~ CF2XOCH3 zClz yFy (wherein z = 1, 2, or 3 y = 1, 2, or 3 Y ~ Z) CA 0222043l Isg7-ll-07 WO96/40371 PCT~S96/08187 The ~ormation o~ CF2HOCH3zClz wherein z = 3 in the above reaction scheme can be inhibited or even eliminated upon the addition o~ an oxygen source, preferably air, to the vapor phase reaction medium. Rather than inhibiting the three chlorination products equally, the addition o~ oxygen surprisingly pre~erentially inhibits the ~ormation o~ CF2HOCCl3.
Any oxygen source not deleterious to the production o~ the desired compounds could be used, including oxygen-cont~;n~ng compounds which liberate oxygen in si tu .
The oxygen should be present in an amount e~ective ~or the desired inhibition. In the case o~ air, pre~erably the air is added in an amount ~rom about 1.5 to about 5.5~ o~ the total gas ~low. Those skilled in the art will recognize that where pure oxygen is used, the amounts will be about l/5 that o~ air.
Preferably the oxygen source is added to the reaction medium ~or as long as the chlorine gas is ~lowing.
It has been ~ound that CHF2OCH3may be suitably chlorinated by lique~ying the CHF2OCH3 and reacting it with chlorine gas while irradiating with a source o~ visible light.
Alternatively, one may use other light sources such as ultraviolet light or heat, a catalyst or a ~ree radical initiator to aid in the reaction. The chlorination products o~ CHF2OCH3 can be readily separated prior to ~luorination or the reaction mixture can be ~luorinated without separation to give an admixture o~ CF2HOCCl2F, CF2HOCF2Cl, CF2HOCH2F/
CF2HOCFHCl, CF2HOCF2H. All separations may be e~ected by ~ractional distillation.
WO96/40371 PCT~S96/08187 A preferred method o~ chlorinating the CHF2OCX3 is to maintain the CHF2OCH3 in a vapor phase and react it with chlorine gas while subjecting the chlorination reaction to a source of light, preferably visible or ultraviolet light.
Alternatively, other reaction aids such as a catalyst, heat or a free radical initiator may be used instead of light in the chlorination reaction.
In the preferred fluorination procedure, the chlorinated reaction product is reacted with anhydrous hydrogen fluoride (HF), which reaction may be represented as follows:
CF2HOCCl3 + 3HF ~ CF2HOCFCl2 * CF2XOCF2Cl + 3XCl Utilizing the above reaction with hydrogen fluoride has resulted in a yield as high as 78~ CF2HOCF2Cl with a small amount of CF2HOCFCl~. This was an unexpected result since HF
by itself does not normally replace a halogen such as chlorine, except perhaps at very high temperatures, but instead fluorinates by continuous regeneration of a fluorinating agent such as SbCl5yFyl such as SbF3, or SbF3Cl2. Apparently, the difluoromethoxy group activates the chlorine on the alpha-carbon atom, allowing it to react readily with HF.
Alternatively, the XF may be diluted with an organic solvent, pre~erably a dipolar aprotic solvent such as methyl pyrrolidone, in order to reduce fragmentation of the ~luorinated material, resulting in higher yields of desired product with less by-product generation. Other sources of ~luorine ~or the fluorination step include metal fluorides that WO96/40371 PCT~S96/08187 can ~orm salts o~ the HF2e anion, such as KHF2, NaHF2, LiHF2, NH4HF2, etc., and pyridine salts of HF and NaF and KF in suitable solvents.
The resultant fluorinated products may be separated by distillation or by the process as taught in U.S. Patent 4,025,567 or U.S. Patent 3,887,439 which are incorporated herein by reference in their entirety.
The Bis(difluoroomethyl)ether thus produced has been found to be e~fective as a fire extinguishant at a m;n;mllm concentration of about ll.7 volume percent in air. In order to increase the rate of expulsion and/or dispersion, the bis(di~luoromethyl)ether can be used in conjuction with inert gases, such as nitrogen, carbon dioxide, CF3H, etc. Carbon dioxide is especially preferred, since it exhibits some degree of solubility in the ether.
The present invention will now be further illustrated by the following examples.
a) Preparation o~ CF2HOCH3 A 25 wt ~ solution o~ sodium methoxide in methanol (1533.lg) containing 7.l moles of sodium methoxide was placed in a 4 liter jacketed autoclave ~itted with a temperature sensor, a pressure gauge and a dipleg. The vessel was cooled to 0 to 5~C and chlorodi~luoromethane (318.2g, 3.70 moles) added over a period of 2.5 hours with agitation. When the addition o~ gas had been completed, the autoclave was slowly warmed to about 60~C while venting gaseous products through the -WO96/40371 PCT/U~-/Ca187 water-cooled con~n~er into a collection trap cooled to about -70~C.
When all volatile material had been collected unreacted CHF~Cl was r~u,o~ed at -20~C and the r~m~;n;ng CF2HOC~
transferred to a metal cylinder. The recovered difluoromethyl methyl ether (150.0g, 1.83 moles) represented a yield of 49.4 based on CF2HCl.
b) Chlorination of CF2HOCH3 Chlorine and CF2HOCH3 in a gaseous phase are passed through separate con~nsers cooled to 0~C and then the gas streams combine and pass into one arm of a U-shaped reactor, irradiated with visible light or W . Both arms of the reactor are jacketed and cooled with water.
There is an outlet at the bottom o~ the U to which is attached a product collection flask. A ]~ewar-type con~n~er cooled to -50~C is attached to the outlet of the second arm of the U-tube and, in turn, it is connected in series with a cold trap to collect unreacted chlorine and an NaOH scrubber to remove HCl. The reaction is normally carried out at atmospheric pressure, but higher or lower pressure can be used.
Temperature should not be allowed to rise much above 50~C in the reactor to avoid attack on the glass.
In practice, the apparatus is flushed with nitrogen and then chlorine and CHF2OCH3 are fed to the reactor at rates such that the ratio of the flow of chlorine to that of the ether is maintained at about 2.5:l for optimum results, i.e., yield of CF2HOCHCl2 A predominant amount of any one o~ the three products can be obtained by changing the ratio of the gas WO 9fi'1~71 PCT!U:~,GJ'~,~187 flows.
After the passage of 2.3 moles o~ chlorine and 0.9 moles of CHF2OCH3, 136.6g of product were recovered. GC analysis o~
the product mixture showed CF2HOCH2Cl 10.0~, CF2HOCHCl2 62.4~, and CF2HOCCl3 22.2~.
c) Fluorination of CHF2OCHCl2 with HF
The chlorinated CHF2OCH3 (40.0g) containing 46.1~ CF2HOCHCl2 in a stainless steel cylinder was then cooled in ice before adding anhydrous HF (30.0g). The cylinder was closed with a valve and pressure gauge and then was placed in a water bath at 60~C for 3 hours. The cylinder was then vented through a NaOH scrubber and volatile products collected in a trap cooled at -70~C. The weight of product recovered from the trap was 16.8g. It contained 71.8~ CF2HOCF2H by GC analysis, corresponding to a yield of 83.8~ of CF2HOCF2H.
When conducted on a larger scale (e.g., 5 gallons), almost ~uantitative yields of CF2HOCF2H (based on CF2HOCHCl2) were obtained.
The chlorination apparatus consisted of two vertical lengths of jacketed glass tubing, 4 feet long by 2 inches I.D., connected at the lower ends in a U-tube fashion by a short length of un]acketed 2 inch I.D. tubing. A drain tube led from the lowest point of the U-tube arrangement so that product could be collected as it formed and removed continuously from the apparatus or alternatively allowed to accumulate in a receiver. Three 150 watt incandescent flood lamps were WO96/40371 PCT/U',.C8187 arranged along the length o~ each tube.
The gases were ~ed into the upper end of one arm o~ the U-tube arrangement. Flow rates were measured by calibrated mass ~lowmeters. A low temperature con~e~er on the outlet o~
the second arm o~ the U-tube returned unreacted E-152a and chlorine to the illuminated reaction zone. Hydrogen chloride by-product and air passed through the coP~n~er into a water scrubber where the hydrogen chloride was removed.
A mixture o~ methanol and water, cooled to O to 5~C was circulated through the cooling jackets of the apparatus.
In a typical run, coolant at a temperature o~ O to 5~C is circulated through the cooling jackets, t:he ~lood lamps were turned on and dry ice placed in the low temperature c~n~n~er.
Chlorine was introduced into the apparatu.s ~irst, ~ollowed by di~luoromethyl ether and air in the desired ratios Product was removed at intervals ~rom the receiver and washed with saturated NaHCO3 solution to l~,L~ove HCl Since the reaction was continuous, it could proceed ~or any length o~ time desired. At the end o~ the reaction, gas ~lows were stopped and product allowed to drain ~rom the vertical reactor tubes into the receiver.
The results are tabulated in Table l below. Examples 6-29-l to 6-29-7 show the distribution o~ products normally obtained without the addition o~ air to the gas stream.
Examples 7-7-3 through 7-8-6 show the e~ect o~ the addition o~ air in ~;m;n; shing amounts, in accordance with the present invention.
-WO96/40371 PCT/U~ 187 TABLEI
Fk~w l~ cs Prcduc: Ç~roduc: Di~ bu~lon m Ta~al ~ Air in Cl2E-152~ rW~zh~ n~ Di- Tn .~oi~ ic R~loG;u F~o~ C~lontle ~u~ ~io (n~h~mn~ (~ns) ('70 (~c cr~; c- ,l7?~ C;~E 5-~l t%) (7c) -I '~ ~~-- o9.o ~.0 ~ .o 0.0-0~~1.0111 I.i _ _ --95 6 ~ 0 1 Qt~.C13 0.01 1~ 1.,~ _ _ 9-~~ ~ .. ,0-- ~1 1 7'.' ;~ l J;.' 0.0-070.01lO 1.3~ -- _ --7$. 1 '. . ' J,~.. J j~. '0.0'03 0.0 1 i ~ t., ~ _ _ ~ 0 ~ 6 ~ 69. ~~ . .0 i .9 _ 0Ø: _ O.O S _ l _._~ , . 1 7 7 7n50 ~0 ~ C 9~ ~ 56.o i .0 ~.5 O.O; ~ S 0.~ c ¦ I 7 ~ i-~-' 900 :0: 6; 1 19.i 18.. ~2.~,5.' O.Oi~5 0.01~ _'i : ~ , 0 116.0 5 . 39O~5 0.036~ Q~IL~ _.7i :o o -7-7-8 930 ~c62 111.' 5~.~ 36._ ;.; 0.03~a 0.01~ :.iO lo o.77-8-'1:3~:) 6CO '5 198.o ~3.0 15.: .. ' QQ~I ~-~~ ' :.i8 Z.7 ~.i 7~18CO ~ 70~.1 '2.~ ~6.. 5.0 0.0~'1 0,030C :.-o 2.1 Z.9 ~-~-0' Cl~ 0 51 ~1. 0 i'.o 5~.~) , ~ 0.08~ 0.0~
The extinguishing con centration o~
Bis(di~luoromethyl)ether was determined using the I.C.I. cup burner method, which is a standard test. The apparatus is shown in Figure l, and consisted of a 8.5 cm by 53 cm tall outer chimney through which air was passed at 40L/min from a glass bead distributor at its base. An inner fuel cup burner with a 3.l cm O.D. and a 2.15 cm I.D. was positioned 30 5 cm below the top edge of the ~.h;mn~y, Bis (difluoromethyl)ether was added to the air stream prior to entering the glass bead distributor. The air flow rate was maintained at 40L/min ~or the trial. Air and bis(difluoromethyl)ether flow rates were measured using rotameters.
The test was conducted by adjusting the extended ~uel reservoir to bring the liquid (heptane) level in the cup burner to just even with the base of a ground glass lip on the burner cup. With the air flow maintained at 40L/min, the fuel in the cup burner was ignited. Bis(difluoromethyl)ether was gradually added to the air stream until the flame was extinguished. The bis-(di~luoromethyl)ether totameter reading was then recorded.
The extinguishing concentration o~ the ether was calculatedd as a percentage of the co~bined ~low of the ether and air.
CA 0222043l ls97-ll-07 WO9-'~C~71 PCT~S96/08187 Re~erence agents Halon 1301 and HFC-227ea were tested similarly. Several runs were made with each test material, and the average values o~ the extinguishing concentration were as ~ollows:
Test Material Extinquishin~ Concentration tVol ~) Halon 1301 2.5 i O.1 HFC-227ea 6.3 i 0.1 Bis(di~luoromethyl)ether 11.7 i 0 3
R~2L ~K~:~o~7D OF T~IE 11!1 V151!1-1 lON
The Halons, particularly 1301 (CF3Br) and 1211 (CF2ClBr), have been used successfully for many years as fire and explosion suppressants. Halon 1301 is generally used in "total flood" applications in which the agent is discharged from a fixed automated system to uniformly fill a space to extinguish a fire or to provide inertion. The agent concentration required for fire suppression is the most important performance parameter in this application.
Halon 1211 is usually used in "streaming" applications in which the halon is discharged from a portable, m~n~
extinguisher to provide localized fire suppression. Both the extinguishment concentration and the discharge characteristics of "streaming" agents are important in determining fire extinguishment capacity.
The vapor pressure of Halon 1301 is 234 psia, and that of Halon 1211 is 40 psia at room temperature. Either system can be pressurized for faster discharge, if needed.
The Halons contain chlorofluorocarbons, and thus have been subject to the same restraints as other compounds of that class in view of their potential to deplete the ozone. Halon 1211 has an atmospheric life of 15 years and an ozone depletion potential (ODP) of 3Ø Halon 1301 has an atmospheric life of 110 years and an ODP of 10Ø When these compounds are released to the atmosphere, they undergo photolitically catalyzed deomposition and the halogen atoms then catalyze the decomposition of ozone. Suitable substitutes must meet . ~ -WO96/40371 PCT/U',G~V~187 certain re~uirements. There should be hydrogen in the molecule in order to facilitate photolytic degradation in the troposphere, but preferably the molecule should contain no halogen other than fluorine. Acceptab]e substitutes would exhibit fire suppressant efficiency, low residue levels, non-conductivity, negligible ODP, low global warming potential (GWP), non-corrosiveness, materials compatibility, stability under long term storage, and low toxicity.
It is therefore an object of the present invention to provide a fire extinguishant that does not su~fer ~rom the drawbacks of conventional exting~ h~nts.
It is a further object of the present invention to provide a method of extinguishing fires while m;n;m; zing the potential for ozone depletion.
S~MARY OF T~E lN V ~ N
The problems of the prior art have been overcome by the present invention, which provides a non-chlorofluorocarbon compound as a fire extinguishant. More specifically, the present inventor has found that Bis(difluoromethyl)ether is non-flammable, has an atmospheric life o~ only 2,8 years, and has zero ozone depletion potential The ether behaves well as a fire extinguishant.
BRIEF DESCRIPTION OF TEE DRAWING
Figure l is a schematic view o~ apparatus used to test ~ire extinguishing concentrations.
DET~ TT-T~n DESCRIPTION OF TEE lNV~N-l-lON
Bis(difluoromethyl)ether can be prepared by a variety of processes conventional in the art. For example, it can be WO96/40371 PCT/U~ 187 prepared by chlorination of dimethyl ether ~ollowed by isolation and fluorination of bis(dichloromethyl)ether. A
preferred approach avoids the unstable complex mixture o~
chlorinated ethers, some of which are carcinogens, by employing methyl difluoromethyl ether as a starting material. The methyl difluoromethyl ether is chlorinated to give a chlorinated reaction mixture including at least one compound of the formula CF2HOCH3zClz, wherein z is l, 2 or 3, which compound can be readily separated from the chlorinated reaction mixture. The chlorination of methyldifluoromethyl ether would generally form only three derivatives, i.e., z=l, z=2 and z-3. The dichloromethyl difluoromethyl ether (z=2) can be readily separated from the chlorinated reaction mixture and is then fluorinated, with or without such separation, to form the bis(difluoromethyl)ether. The production of CF2HOCCl3 (z=3) can be inhibited, and any produced also may be separated from the chlorination reaction product and fluorinated. Alternatively, the chlorination reaction product itself may be fluorinated (without prior separation) as follows:
CF2HOCH2Cl > CF2HOCH2F (I) _______~ CF2HOCHClF
CF2HOCHCl2 ~ CF2HOCHF2 (II) _, CF2HOCCl2F
CF2HOCCl3 ~ ) CF2HOCClF2 CF2HOCF3 (III) The methyl difluoromethyl ether which is regarded as the starting material for the process of the present invention is a known compound which may be prepared in the m~nn~ reported by Hine and Porter in their aforementioned article published in the Journal of the American Chemical Society. Specifically, r difluoromethyl methyl ether is produced by reaction of sodium methoxide (NaOMe) with chlorodifluoromethane (CF2HCl), which reaction may be represented as follows:
CF2HCl + CH30Na -----------~ CF2HOCH3 + NaCl Briefly, the method involves forming an alcohol solution of sodium methoxide and bubbling the chlorodi~luoromethane slowly into the reaction mixture to obtain the wethyldi~luoromethyl ether as a residue in the reaction mixture. Some product is entrained with unreacted CF2HCl and can be separated from it in a distillation operation.
The starting ether, CHF20CH3, also m:ight be prepared by first reacting NaOH with CH30H, in ef~ect making CH30Na, and then reacting it with CF2HCl. However, water is also formed in the NaOH/C~OH reaction. The effect water has on the subsequent reaction to form CHF20CH3 is to reduce the yield of CHF20CH3 .
The chlorination and fluorination steps of this invention can be represented as follows:
zCl2 CHF2OCH3 ----------~ CF2HOCH3zClz + zHCl (wherein z = 1,2,or 3) F
CF2HOCH3 zClz - - - - - - - ---- - ~ CF2XOCH3 zClz yFy (wherein z = 1, 2, or 3 y = 1, 2, or 3 Y ~ Z) CA 0222043l Isg7-ll-07 WO96/40371 PCT~S96/08187 The ~ormation o~ CF2HOCH3zClz wherein z = 3 in the above reaction scheme can be inhibited or even eliminated upon the addition o~ an oxygen source, preferably air, to the vapor phase reaction medium. Rather than inhibiting the three chlorination products equally, the addition o~ oxygen surprisingly pre~erentially inhibits the ~ormation o~ CF2HOCCl3.
Any oxygen source not deleterious to the production o~ the desired compounds could be used, including oxygen-cont~;n~ng compounds which liberate oxygen in si tu .
The oxygen should be present in an amount e~ective ~or the desired inhibition. In the case o~ air, pre~erably the air is added in an amount ~rom about 1.5 to about 5.5~ o~ the total gas ~low. Those skilled in the art will recognize that where pure oxygen is used, the amounts will be about l/5 that o~ air.
Preferably the oxygen source is added to the reaction medium ~or as long as the chlorine gas is ~lowing.
It has been ~ound that CHF2OCH3may be suitably chlorinated by lique~ying the CHF2OCH3 and reacting it with chlorine gas while irradiating with a source o~ visible light.
Alternatively, one may use other light sources such as ultraviolet light or heat, a catalyst or a ~ree radical initiator to aid in the reaction. The chlorination products o~ CHF2OCH3 can be readily separated prior to ~luorination or the reaction mixture can be ~luorinated without separation to give an admixture o~ CF2HOCCl2F, CF2HOCF2Cl, CF2HOCH2F/
CF2HOCFHCl, CF2HOCF2H. All separations may be e~ected by ~ractional distillation.
WO96/40371 PCT~S96/08187 A preferred method o~ chlorinating the CHF2OCX3 is to maintain the CHF2OCH3 in a vapor phase and react it with chlorine gas while subjecting the chlorination reaction to a source of light, preferably visible or ultraviolet light.
Alternatively, other reaction aids such as a catalyst, heat or a free radical initiator may be used instead of light in the chlorination reaction.
In the preferred fluorination procedure, the chlorinated reaction product is reacted with anhydrous hydrogen fluoride (HF), which reaction may be represented as follows:
CF2HOCCl3 + 3HF ~ CF2HOCFCl2 * CF2XOCF2Cl + 3XCl Utilizing the above reaction with hydrogen fluoride has resulted in a yield as high as 78~ CF2HOCF2Cl with a small amount of CF2HOCFCl~. This was an unexpected result since HF
by itself does not normally replace a halogen such as chlorine, except perhaps at very high temperatures, but instead fluorinates by continuous regeneration of a fluorinating agent such as SbCl5yFyl such as SbF3, or SbF3Cl2. Apparently, the difluoromethoxy group activates the chlorine on the alpha-carbon atom, allowing it to react readily with HF.
Alternatively, the XF may be diluted with an organic solvent, pre~erably a dipolar aprotic solvent such as methyl pyrrolidone, in order to reduce fragmentation of the ~luorinated material, resulting in higher yields of desired product with less by-product generation. Other sources of ~luorine ~or the fluorination step include metal fluorides that WO96/40371 PCT~S96/08187 can ~orm salts o~ the HF2e anion, such as KHF2, NaHF2, LiHF2, NH4HF2, etc., and pyridine salts of HF and NaF and KF in suitable solvents.
The resultant fluorinated products may be separated by distillation or by the process as taught in U.S. Patent 4,025,567 or U.S. Patent 3,887,439 which are incorporated herein by reference in their entirety.
The Bis(difluoroomethyl)ether thus produced has been found to be e~fective as a fire extinguishant at a m;n;mllm concentration of about ll.7 volume percent in air. In order to increase the rate of expulsion and/or dispersion, the bis(di~luoromethyl)ether can be used in conjuction with inert gases, such as nitrogen, carbon dioxide, CF3H, etc. Carbon dioxide is especially preferred, since it exhibits some degree of solubility in the ether.
The present invention will now be further illustrated by the following examples.
a) Preparation o~ CF2HOCH3 A 25 wt ~ solution o~ sodium methoxide in methanol (1533.lg) containing 7.l moles of sodium methoxide was placed in a 4 liter jacketed autoclave ~itted with a temperature sensor, a pressure gauge and a dipleg. The vessel was cooled to 0 to 5~C and chlorodi~luoromethane (318.2g, 3.70 moles) added over a period of 2.5 hours with agitation. When the addition o~ gas had been completed, the autoclave was slowly warmed to about 60~C while venting gaseous products through the -WO96/40371 PCT/U~-/Ca187 water-cooled con~n~er into a collection trap cooled to about -70~C.
When all volatile material had been collected unreacted CHF~Cl was r~u,o~ed at -20~C and the r~m~;n;ng CF2HOC~
transferred to a metal cylinder. The recovered difluoromethyl methyl ether (150.0g, 1.83 moles) represented a yield of 49.4 based on CF2HCl.
b) Chlorination of CF2HOCH3 Chlorine and CF2HOCH3 in a gaseous phase are passed through separate con~nsers cooled to 0~C and then the gas streams combine and pass into one arm of a U-shaped reactor, irradiated with visible light or W . Both arms of the reactor are jacketed and cooled with water.
There is an outlet at the bottom o~ the U to which is attached a product collection flask. A ]~ewar-type con~n~er cooled to -50~C is attached to the outlet of the second arm of the U-tube and, in turn, it is connected in series with a cold trap to collect unreacted chlorine and an NaOH scrubber to remove HCl. The reaction is normally carried out at atmospheric pressure, but higher or lower pressure can be used.
Temperature should not be allowed to rise much above 50~C in the reactor to avoid attack on the glass.
In practice, the apparatus is flushed with nitrogen and then chlorine and CHF2OCH3 are fed to the reactor at rates such that the ratio of the flow of chlorine to that of the ether is maintained at about 2.5:l for optimum results, i.e., yield of CF2HOCHCl2 A predominant amount of any one o~ the three products can be obtained by changing the ratio of the gas WO 9fi'1~71 PCT!U:~,GJ'~,~187 flows.
After the passage of 2.3 moles o~ chlorine and 0.9 moles of CHF2OCH3, 136.6g of product were recovered. GC analysis o~
the product mixture showed CF2HOCH2Cl 10.0~, CF2HOCHCl2 62.4~, and CF2HOCCl3 22.2~.
c) Fluorination of CHF2OCHCl2 with HF
The chlorinated CHF2OCH3 (40.0g) containing 46.1~ CF2HOCHCl2 in a stainless steel cylinder was then cooled in ice before adding anhydrous HF (30.0g). The cylinder was closed with a valve and pressure gauge and then was placed in a water bath at 60~C for 3 hours. The cylinder was then vented through a NaOH scrubber and volatile products collected in a trap cooled at -70~C. The weight of product recovered from the trap was 16.8g. It contained 71.8~ CF2HOCF2H by GC analysis, corresponding to a yield of 83.8~ of CF2HOCF2H.
When conducted on a larger scale (e.g., 5 gallons), almost ~uantitative yields of CF2HOCF2H (based on CF2HOCHCl2) were obtained.
The chlorination apparatus consisted of two vertical lengths of jacketed glass tubing, 4 feet long by 2 inches I.D., connected at the lower ends in a U-tube fashion by a short length of un]acketed 2 inch I.D. tubing. A drain tube led from the lowest point of the U-tube arrangement so that product could be collected as it formed and removed continuously from the apparatus or alternatively allowed to accumulate in a receiver. Three 150 watt incandescent flood lamps were WO96/40371 PCT/U',.C8187 arranged along the length o~ each tube.
The gases were ~ed into the upper end of one arm o~ the U-tube arrangement. Flow rates were measured by calibrated mass ~lowmeters. A low temperature con~e~er on the outlet o~
the second arm o~ the U-tube returned unreacted E-152a and chlorine to the illuminated reaction zone. Hydrogen chloride by-product and air passed through the coP~n~er into a water scrubber where the hydrogen chloride was removed.
A mixture o~ methanol and water, cooled to O to 5~C was circulated through the cooling jackets of the apparatus.
In a typical run, coolant at a temperature o~ O to 5~C is circulated through the cooling jackets, t:he ~lood lamps were turned on and dry ice placed in the low temperature c~n~n~er.
Chlorine was introduced into the apparatu.s ~irst, ~ollowed by di~luoromethyl ether and air in the desired ratios Product was removed at intervals ~rom the receiver and washed with saturated NaHCO3 solution to l~,L~ove HCl Since the reaction was continuous, it could proceed ~or any length o~ time desired. At the end o~ the reaction, gas ~lows were stopped and product allowed to drain ~rom the vertical reactor tubes into the receiver.
The results are tabulated in Table l below. Examples 6-29-l to 6-29-7 show the distribution o~ products normally obtained without the addition o~ air to the gas stream.
Examples 7-7-3 through 7-8-6 show the e~ect o~ the addition o~ air in ~;m;n; shing amounts, in accordance with the present invention.
-WO96/40371 PCT/U~ 187 TABLEI
Fk~w l~ cs Prcduc: Ç~roduc: Di~ bu~lon m Ta~al ~ Air in Cl2E-152~ rW~zh~ n~ Di- Tn .~oi~ ic R~loG;u F~o~ C~lontle ~u~ ~io (n~h~mn~ (~ns) ('70 (~c cr~; c- ,l7?~ C;~E 5-~l t%) (7c) -I '~ ~~-- o9.o ~.0 ~ .o 0.0-0~~1.0111 I.i _ _ --95 6 ~ 0 1 Qt~.C13 0.01 1~ 1.,~ _ _ 9-~~ ~ .. ,0-- ~1 1 7'.' ;~ l J;.' 0.0-070.01lO 1.3~ -- _ --7$. 1 '. . ' J,~.. J j~. '0.0'03 0.0 1 i ~ t., ~ _ _ ~ 0 ~ 6 ~ 69. ~~ . .0 i .9 _ 0Ø: _ O.O S _ l _._~ , . 1 7 7 7n50 ~0 ~ C 9~ ~ 56.o i .0 ~.5 O.O; ~ S 0.~ c ¦ I 7 ~ i-~-' 900 :0: 6; 1 19.i 18.. ~2.~,5.' O.Oi~5 0.01~ _'i : ~ , 0 116.0 5 . 39O~5 0.036~ Q~IL~ _.7i :o o -7-7-8 930 ~c62 111.' 5~.~ 36._ ;.; 0.03~a 0.01~ :.iO lo o.77-8-'1:3~:) 6CO '5 198.o ~3.0 15.: .. ' QQ~I ~-~~ ' :.i8 Z.7 ~.i 7~18CO ~ 70~.1 '2.~ ~6.. 5.0 0.0~'1 0,030C :.-o 2.1 Z.9 ~-~-0' Cl~ 0 51 ~1. 0 i'.o 5~.~) , ~ 0.08~ 0.0~
The extinguishing con centration o~
Bis(di~luoromethyl)ether was determined using the I.C.I. cup burner method, which is a standard test. The apparatus is shown in Figure l, and consisted of a 8.5 cm by 53 cm tall outer chimney through which air was passed at 40L/min from a glass bead distributor at its base. An inner fuel cup burner with a 3.l cm O.D. and a 2.15 cm I.D. was positioned 30 5 cm below the top edge of the ~.h;mn~y, Bis (difluoromethyl)ether was added to the air stream prior to entering the glass bead distributor. The air flow rate was maintained at 40L/min ~or the trial. Air and bis(difluoromethyl)ether flow rates were measured using rotameters.
The test was conducted by adjusting the extended ~uel reservoir to bring the liquid (heptane) level in the cup burner to just even with the base of a ground glass lip on the burner cup. With the air flow maintained at 40L/min, the fuel in the cup burner was ignited. Bis(difluoromethyl)ether was gradually added to the air stream until the flame was extinguished. The bis-(di~luoromethyl)ether totameter reading was then recorded.
The extinguishing concentration o~ the ether was calculatedd as a percentage of the co~bined ~low of the ether and air.
CA 0222043l ls97-ll-07 WO9-'~C~71 PCT~S96/08187 Re~erence agents Halon 1301 and HFC-227ea were tested similarly. Several runs were made with each test material, and the average values o~ the extinguishing concentration were as ~ollows:
Test Material Extinquishin~ Concentration tVol ~) Halon 1301 2.5 i O.1 HFC-227ea 6.3 i 0.1 Bis(di~luoromethyl)ether 11.7 i 0 3
Claims (5)
1. A fire extinguishant, consisting essentially of a fire extinguishing effective amount of bis(difluoromethyl) ether.
2. The fire extinguishant of claim 1, further comprising an inert gas for expelling or dispersing said bis(difluoromethyl)ether.
3. The fire extinguishment of claim 2, wherein said inert gas is selected from the group consisting of nitrogen, carbon dioxide and CHF3.
4. A method of extinguishing fires, comprising applying to said fire a fire extinguishing effective amount of bis(difluoromethyl)ether.
5. The method of claim 4, wherein said fire extinguishing effect amount is such that the minimum concentration of said bis(difluoromethyl)ether in air is 11.7 volume percent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US48400595A | 1995-06-07 | 1995-06-07 | |
| US08/484,005 | 1995-06-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2220431A1 true CA2220431A1 (en) | 1996-12-19 |
Family
ID=23922346
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002220431A Abandoned CA2220431A1 (en) | 1995-06-07 | 1996-05-31 | The use of bis(difluoromethyl)ether as a fire extinguishant |
Country Status (12)
| Country | Link |
|---|---|
| EP (1) | EP0841967A4 (en) |
| JP (1) | JPH11506648A (en) |
| CN (1) | CN1199349A (en) |
| AU (1) | AU699193B2 (en) |
| BR (1) | BR9609407A (en) |
| CA (1) | CA2220431A1 (en) |
| DE (1) | DE841967T1 (en) |
| ES (1) | ES2128279T1 (en) |
| MX (1) | MX9709476A (en) |
| TW (1) | TW349874B (en) |
| WO (1) | WO1996040371A1 (en) |
| ZA (1) | ZA964268B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1283203B1 (en) * | 1996-03-07 | 1998-04-16 | Ausimont Spa | FIRE EXTINGUISHING COMPOSITIONS |
| CN106823227B (en) * | 2017-03-17 | 2019-08-16 | 公安部天津消防研究所 | A kind of higher boiling gas extinguishing agent extinguishing concentration experimental rig and test method |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2066905A (en) * | 1935-03-23 | 1937-01-05 | Westinghouse Electric & Mfg Co | Halogenated methyl ethers |
| CA1075854A (en) * | 1976-08-16 | 1980-04-22 | Charles W. Simons | Aerosol propellants for personal products |
| US5611210A (en) * | 1993-03-05 | 1997-03-18 | Ikon Corporation | Fluoroiodocarbon blends as CFC and halon replacements |
| GB9403334D0 (en) * | 1993-04-23 | 1994-04-13 | Ici Plc | Process for rigid polyurethane foams |
| US5484546A (en) * | 1993-05-19 | 1996-01-16 | E. I. Du Pont De Nemours And Company | Refrigerant compositions including an acylic fluoroether |
-
1996
- 1996-05-27 ZA ZA964268A patent/ZA964268B/en unknown
- 1996-05-31 CA CA002220431A patent/CA2220431A1/en not_active Abandoned
- 1996-05-31 ES ES96919022T patent/ES2128279T1/en active Pending
- 1996-05-31 JP JP9500906A patent/JPH11506648A/en active Pending
- 1996-05-31 BR BR9609407A patent/BR9609407A/en not_active Application Discontinuation
- 1996-05-31 MX MX9709476A patent/MX9709476A/en unknown
- 1996-05-31 CN CN96194633A patent/CN1199349A/en active Pending
- 1996-05-31 EP EP96919022A patent/EP0841967A4/en not_active Withdrawn
- 1996-05-31 AU AU61475/96A patent/AU699193B2/en not_active Ceased
- 1996-05-31 WO PCT/US1996/008187 patent/WO1996040371A1/en not_active Application Discontinuation
- 1996-05-31 DE DE0841967T patent/DE841967T1/en active Pending
- 1996-06-04 TW TW085106651A patent/TW349874B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| CN1199349A (en) | 1998-11-18 |
| BR9609407A (en) | 1999-05-11 |
| AU6147596A (en) | 1996-12-30 |
| MX9709476A (en) | 1998-02-28 |
| EP0841967A4 (en) | 1999-11-17 |
| ZA964268B (en) | 1996-12-04 |
| TW349874B (en) | 1999-01-11 |
| ES2128279T1 (en) | 1999-05-16 |
| EP0841967A1 (en) | 1998-05-20 |
| DE841967T1 (en) | 1999-02-25 |
| AU699193B2 (en) | 1998-11-26 |
| JPH11506648A (en) | 1999-06-15 |
| WO1996040371A1 (en) | 1996-12-19 |
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