CA1321797C - Process for preparing telomers from chlorotrifluoroethylene and 1,1-dibromo-1- chlorotrifluoroethane - Google Patents
Process for preparing telomers from chlorotrifluoroethylene and 1,1-dibromo-1- chlorotrifluoroethaneInfo
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/26—Preparation of halogenated hydrocarbons by reactions involving an increase in the number of carbon atoms in the skeleton
- C07C17/272—Preparation of halogenated hydrocarbons by reactions involving an increase in the number of carbon atoms in the skeleton by addition reactions
- C07C17/278—Preparation of halogenated hydrocarbons by reactions involving an increase in the number of carbon atoms in the skeleton by addition reactions of only halogenated hydrocarbons
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Abstract
TELOMERS PREPARED FROM CHLOROTRIFLUOROETHYLENE
AND 1,1-DIBROMO-1-CHLOROTRIFLUOROETHANE
ABSTRACT
Telomers are prepared by reacting chlorotrifluoroethylene with l,l-dibromo-l-chlorotrifluoroethane (CBr2C1CF3) in the presence of a redox catalyst system comprising a reducible metal compound selected from the group consisting of FeC13, FeBr3, Fe2(SO4)3, CuBr2, CuC12, TiC14, VC13, and NiC12, and a reducing agent selected from the group consisting of Fe, Ni, Cu, Ti, V and benzoin.
Alternatively, the metal compound can also be used in its reduced form without a reducing agent. Suitable reduced metal compounds include FeC12, FeBr2, FeSO4, CuBr and CuCl. The preferred catalyst system is ferric chloride and nickel. The telomers of this invention are useful for preparing non-flammable hydraulic fluids.
AND 1,1-DIBROMO-1-CHLOROTRIFLUOROETHANE
ABSTRACT
Telomers are prepared by reacting chlorotrifluoroethylene with l,l-dibromo-l-chlorotrifluoroethane (CBr2C1CF3) in the presence of a redox catalyst system comprising a reducible metal compound selected from the group consisting of FeC13, FeBr3, Fe2(SO4)3, CuBr2, CuC12, TiC14, VC13, and NiC12, and a reducing agent selected from the group consisting of Fe, Ni, Cu, Ti, V and benzoin.
Alternatively, the metal compound can also be used in its reduced form without a reducing agent. Suitable reduced metal compounds include FeC12, FeBr2, FeSO4, CuBr and CuCl. The preferred catalyst system is ferric chloride and nickel. The telomers of this invention are useful for preparing non-flammable hydraulic fluids.
Description
~3~3.7~7 PROCESS FOR PREPARING TELOMERS
FROM CIILOROTRIFLUOROETHYLENE AND
l,l-DIBROI~O-l-CIlLOROTRIFLUOROETHANE
B~CKGROUND OF THE INVENTION
_ .
T)le present invelltion relates to a process for preparing telomers of the Forlllula F Br r F F
F - C - C - - C - C- - Br l l F Cl F Cl n where n is in the range of 1 to 10. The telomers of this invent;on are saturated, low nlolecular weight polymers which are useful for preparing non-flamlllable hydraulic fluids.
Va~^ious methods of prepar;ng chlorotrifluoroethylene ("CTFE") telomers are known in the pr;or art and have been practiced commer-cially for many years. An article by William T. Miller, Jr. et al in Industrial and Engineeriny Chemistry, pages 333-337 (1947), entitled "Low Polymers of Chlorotrifluoroethylene", describes a process for producing low molecular weight polymers of CTFE by polymerization in a solution of chlorofonn using benzoyl peroxide as a polymerization pro-moter. Other solvents disclosed in the reference as being useful for this purpose include carbon tetrachloride and tetrachloroethylene.
The solution is heated in a pressure vessel for 1-3/4 hours at 100C, and tlle unreacted CTFE monomer and chloroform are rernoved by distil-~
.
7 ~ 7 lation, leaving a crude telomer of general formula CHC12(CF~CClF)nCl,which can be further heated and distilled to yield products ranging from a light oil to a semi-solid wax or grease.
Another process for preparing low molecular weight CTFE polymers is described in U.S. Patent No. 2,788,375, issued April 9, 1957. This process comprises reacting CTFE with a saturated brominated compound in the presence of a source of radiation. Suitable brominated com-pounds include l,2-dibromo-2-chlorotri-fluoroethane (CF2BrCClFBr).
The saturated bromopolychlorofluoro compounds obtained by this process lU can then be distilled, and the isolated fractions reacted with chlor-ine to prepare polychlorofluorocompounds. The compounds are predomi-nantly higher molecular weight telomers, i.e. n is greater than 4.
Czechoslovakian Patent No. 201,708, published August 15, 1982, discloses the reaction of CTFE with CBrClFCF2Br using a source of radiation at a temperature of from 20C to 30C to prepare 1,4-dibromo-2,3-dichlorohexafluorobutane and 1,6-dibromo-2,3,5-trichlorononafluorohexane as principal reaction products. These compounds are designated by the following structural formulas:
F F IF F
Br ~C - C - C C Br (1) F Cl Cl F
F F F F F F
BrC - C -C C - C - C - Br (2) F Cl F Cl Cl F
Both compounds (1) and (2) share the common feature of haYing the same end groups, i.e., --CF2Br, as well as ad~acent pairs of -CFCl- groups in the body of the telomer. Telomers having structures such as (1) and (2) are believed to be inherently more unstable and are less easily separated from impurities than the telomers of the present invention.
) rd .~
A Inore recent development in this field is described in a series of articles by Y. Pietrasanta et al entitled Telomerization by Redox Catalysis appeariny in the Eruopean Pol~n__Journal Vol 12 (1976).
This technology involves the reaction of single carbon halogenated 5 telogells, such as CC14 and CC13~r, with CTFE in the presence ~f ben-zoin and a su;table redox catalyst such as ferr;c chloride. The telomer;zation react;on ;s su;tably carried out in acetonitrile wllicll is a collunon sQlvent for the reactants and catalysts. The telomeriza-t;on reaction can be illustrated as follows:
FeC13 CC13X + nCF2-CFCl ~ CC13(CF2CFCl~nX (3) Benzoin where X is chlorine or bromine. The reference further discloses that the use of CC13Br as a telogen results in a lower degree o~ telomeri-zation and a higher proportion of monoaddition product than would occur with the use of CC14.
The redox process bas the advantage of directly preparing low molecular weight products without the necessity of cracking or frac-tionating a higher molecular weight polymer.
A modific~tion of the redox crocess is disclosed in commonlv assigned U.S.Patent 4,808,760, issued ~ebruary 28, 1989, B. Dannels e. al.
In this modification telomers of the structural formula F F F F
Br C - C -C -C- - Br (4) F Cl F Cl In where n is in the range of 1 to 10 are prepared by reacting chlorotrifluoroethylene with 1 2-dibromo-2-chlorotrifluoroethane (CBrClFCF2Br) in the presence of a redox catalvst sYs1:~m~ The redox catalyst system comprises a reducible metal ~alide Selected from the group cons;st;ng of FeC13 FeBr3 CuBr2 CuC12 TiC14 YC13 and NiC12 ~' rd~
and a reducing agent selected from the group consisting of Fe, Ni, Cu, Ti, V and benzoin. This process;has the advantage of being able to prepare CTFE telomers which can be readily separated into relatively pure, stable, low molecular weight isomers, which can be further chlorinated to prepare non-flammable hydraulic fluids.
Although telomers produced according to this latter process represent a significant advance over the prior art, there is still a need to increase the yield of the more desirable low molecular weight species using milder reaction conditions.
SUMMARY OF THE _NVENTION
In accordance with the present invention, distribution of the structural ~ormula is prepared by reacting chlorotrifluoroethylene with l,l-dibromo-l-chlorotrifluoroethane (CF3CClBr2) in the presence of a redox catalyst system. The redox catalyst system comprises a reducible metal compound selected from the group consisting of FeC13, FeBr3, E'e2(SO~)3 CuBr2, CuC12, TiC14, VC13 and NiC12, and a reducing agent selected from the group conSiSting of Fe, Ni, Cu, Ti, V and benzoin. Alternatively, the catalyst system can comprise a metal compound in reduced form without a reducing agent. Suitable reduced metal compounds include FeC12, FeBr2, FeSO4, CuBr and CuCl. The reaction is conducted in a common solvent for the reactants and catalysts, preferably acetonitrile, and the preferred catalyst system is ferric chloride and nickel.
Preferably, the distribution telomers are of the structural formula f~ .
~J
~ 3 ~
F Br F F
l l F C C - C--C ---B r ( 5 ) F Cl F Cl n where n is in the range of 1 to 10.
The telomers may particularly comprise straight-chain telomers of formula CF3CClBr(CF2CFCl)nBr and branched isomers of formula Br(CFClCF2)aCClCF3(CF2CFCl)bBr where n, a and b are in the range of 1 to 10, and the sum of a and b is not more than 10.
The telomerization reaction of the present invention occurs at relatively low temperatures of from about 70C to about 150C, and the reaction produces a relatively high yield o~ low molecular weight species.
` - 4a -~`
J ~ ~
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The telomerization process of the present invention involves the react;on of chlorotrifluoroethylene with l,l-dibromo-l-chlorotri-fluoroethane in a solvent, such as acetonitr;le, ;n the presence of a 5 catalytic amount of a reducible ~letal compound and a suitable metal, or a reduced metal cor.g?ound alone. ~his process can be illustrated as follows:
CF3CClBr + nCF2=CFCl~CF2BrCFCl(CF2CFCl)nBr (6) where n is in the range of 1 to 10.
In reaction (6), K can be a redox catalyst system comprising a reducible metal compound selected frcm the group consisting of FeC13, FeBr3, Fe2(SO4)~9CuBr2, CuC12, TiC14, VC13 and NiC13, and a reducing agent selected from the group cons;sting of iron, nickel, copper, titanium, vanadium and benzoin, where the reducing agent must be capable of reduc;ng the metal compound selected. Typical co~b`in~t:ions of metal halides and reducing agents which are operable include FeC13 or FeBr3 and Fe or Ni, TiC14 and Ti, CuC12 or CuBr2 and Cu, NiC13 and Ni, YC13 and V, and preferably FeC13 and Ni, Mixtures and alloys of the metal reducing agents are also operable in this invention. Alter-natively, K can ccmprise a reduced metal cc~npound without a reducingagent, the reduced metal compound o~ FeC12, FeBr2, FeS04, CuBr and CuCl. Reaction (6) ;s conducted in a common solvent such as ace-tonitr;le, benzonitrile or propionitrile, and preferably acetonitrile.
Reaction (6) results in the preparation of a mixture or distribution of individual telomer species having molecular weights corresponding to n values of from 1 to 10, rather than pure isomers having a discrete structure, i.e. a single n value. Separat;on of the individual telomer species from the mixture is accomplished by distil-lation using procedures well known to those skilled in this art.
~r ~32~ 7 The lighter molecular weight telomers i.e., telomers having an n value of 4 or less, generally predominate in reaction (6). Some of the lighter weight materials, such as the telomer corresponding to an n value of 1, have no known commercial value. ~owever, this telomer can be readily returned or recycled to the telomierzation reaction, and thereby converted into useful telomer products of higher molecular weight, thus increasing the overall efficiency of the reaction. Other telomers are of considerable current interest. For instance, non-flammable hydraulic fluids require an average molecular weight corre-sponding to an n value intermediate between 2 and 4. These fluids canbe produced by first preparing indi~idual stabilized, i.e. chlori-nated, telomers having n values between 2 and 4, and blending these telomers to obtain the desired viscosity. Control of the molecular weight distribution in reaction (6) is there~bre essential since the most desirable products require a narrow molecular weight distribu-tion. This can be achieved by ma;nta;n;n~ the concentration of metal halide (reducible or reduced) in the~r~,a$tion mixture in the range of from about O.Olx to about 2% by weighl't of CTFE, and also maintaining the concentration of reducing agent ~n the reaction m~Xture in an amount of from about 0.5~ to about 3~ by wei~ of CTFE. Following the process of this invention, yi~ of telomer having an n value of 2 to 4 of 50 percent or more can be~chieve~d~
The preferred metal reducing agent is nickel and nickel alloys such as Hastelloy C (Hastelloy is a registered trademark of the Union Carbide Corporation). The metal may be physically present ;n the re-action mixture in a variety of form~, such as a powder, particles of various sizes, wires, plates, or as a cladding material on the inter-nal surface of the reactor. The preferred form is a finely divided powder which is uniformly dispersed in the reaction vessel by means of mechanical agitation, such as in a stirred reactor.
The telomerization reaction is preferably conducted in a stirred reactor under elevated temperature and pressure conditions, with tem-peratures generally ranging from about 70C to about 150C, and pres-sures generally in the range of from about 75 psi to about 450 psi.
~32.1.~.~7 The products of reaction (6) are distinguished by the distribution of -CF2-, -CFCl- and -CBrCl- groups in the telomer chain, and by the presence of one -CF3 and one -CFClBr end group. These telomers can be represented by the following structure:
rF ,1 F - C ~ C - C- Br (5) F Cl F C n The telomers of formula (5) have a bromine atom on the terminal carbon atom, as well as a bromine on the second carbon of the opposite end of the chain. Both of these bromines are sufficiently rPactive to participate in a reinitiation reaction, although the secondary bromine is somewhat less reactive than the primary bromine. Reinitiation of the secondary bromine frequently occurs when FeC13 is selected as the reducible metal compound of choice, and results in a chain that has a trifluoromethyl branch as follows:
Fe~l3 ICF3 CF3CClBr(CF2CFCl)nBr+CF2=CFCl- --rBr(CFClCF2)aCCl(CF2CFCl)bBr (7) where the sum of a and b is not more than 10. Consequently, the pro~ucts of reaction (6) can consist of both straight chain and branched isomers which can be present in the final product in varying degrees.
The follow;ng examples are intended to further illustrate the various embodiments and advantages of the present ;nvention without limiting it thereby. These examples illustrate the preparation of CTFE telomers using various telogens and telomerization processes.
100 9. of CF3CClBr2, 60 9. acetonitrile, 1.5 g. FeC13, and 200 9.
N; powder were placed into the glass liner of a 600 ml. stirred auto-i ~
.
1~2~ 7~
clave . After pressure checking and flushing with N2, 120 9. of CTFE
was added. The autoclave was closed and slowly heated to 120C. The reaction was maintained at this temperature for 4 hours. The maximum pressure reached was 215 psig. As the reaction progressed, an addi-tional 47 9. of CTFE was added from a heated reservoir. The reactorwas then cooled to room temperature, and unreacted CTFE vented off.
Upon opening the autoclave, 123 grams of reaction mixture was obtained which consisted of two liquid phases. This product was washed with dilute HCl and then with water. GC analysis of the washed product indicated that approxima~ely 60 percent of the CF3CClBr2 had reacted. The four (4) carbon telomer made up about 52% of the pro-duct, and appeared to be composed of a single isomer. The six (6) carbon telomer consis~ed of two isomers, one straight chain, the o~her branched. More of the branched isomer than the straight chain isomer was present. Some resuffling of the bromine and chlorine on the telogen was observed. Both CF3CBr3 and CF3CC12Br were found in the product, along with a m;nor amount of each telomer series based upon each of these materials.
100 9. of CF3CClBr2, 60 9. acetonitrile, 3.0 FeC13, and 3.0 g. Fe powder was pl aced i nto the 9l ass 1 i ner of a 600 ml . sti rred autocl ave .
After pressure checking and flushing with N2, 111 9. of CTFE was added. The autoclave was closed and slowly heated to 120C. The re-action was maintained at this temperature for 4 hours. The maximum pressure reached was 200 psig. As the reaction progressed, an addi-tional 59 9. of CTFE was added from a heated reservoir. The reactor was then cooled to room temperature, and unreacted CTFE vented off.
Upon opening the autoclave, 169 grams of reaction mixture was obtained. The product was washed with dilute HCl and then with water, GC analysis of the washed product indicated that approximately 70~ of the CF3CClBr2 had reacted. The four (4) carbon telomer made up about 42X of the product, and appeared to be composed of a single isomer. A
7 ~ ~
larger amount of the resuffled telogens were found in this product than in the product of Example 1.
50 9. of CF3CClBr2, 30 9. acetonitrile, and 2.0 9. FeC12 were placed into the glass liner of a 600 mlO stirred autoclave . After pressure checking and flushing with N2, 112 9. of CTFE was added. The autoclave was closed and slowly heated to 100C. The reaction was maintained at this temperature for 4 hours. The maximum pressure reached was 220 psig. As the reaction progressed7 an add;t;onal 22 g.
of CTFE was added from a heated reservoir. The reactor was then cooled to room temperature, and unreacted CTFE vented off.
Upon open;ng the autoclave, 75 grams of react;on mixture was obtained. This product was washed with dilute HCl and then with water. GC analysis of the washed product ind;cated that approximately 57X of the CF3CClBr2 had reacted. The four (4) carbon telomer made up about 36g of the product~ and appeared to be composed of a single isomer. The straight chain isomer made up the major portion of the six (6) carbon telomer. A smaller amount of resuffled products were present than in the two preceeding examples.
125 9. of CF3CClBr2, 75 9. aceton;tr;le, 7.5 9. Fe2(S04)3 and 5 9. benzo;n were placed into the glass liner of a 600 ml. stirred auto-clave. After pressure checking and flushing with N2, 254 g. of CTFE
was added. The autoclave was closed and slowly heated to 115C. The reaction was maintained at this temperature for 4 hours. The maximum pressure reached was 360 psig. The reactor was then cooled to room temperature, and unreacted CTFE vented off. Upon opening the auto-clave~ 125 grams of reaction mixture was obtained. Th;s crude product was washed with d;lute HCl and then with water. GC analysis of the washed product indicated that approximately 54X of the CF3CClBr2 had reacted. The product was composed of:
1 3 ~d .~ 7 Four (4) Carbon Telomer 39~
Six (6) Carbon Telomer 26%
Eight (8) Carbon Telomer l9X
Ten (10) Carbon Telomer 6g While various embodiments and exemplifications of this invention have been shown and described in the specification, modifications and variations thereof will be readily appreciated by those skilled in the art. It is to be understood, therefore, that the appended claims are intended to cover all such modfîcat;ons and var;ations wh;ch are considered to be within the scope and spirit of the present invention.
FROM CIILOROTRIFLUOROETHYLENE AND
l,l-DIBROI~O-l-CIlLOROTRIFLUOROETHANE
B~CKGROUND OF THE INVENTION
_ .
T)le present invelltion relates to a process for preparing telomers of the Forlllula F Br r F F
F - C - C - - C - C- - Br l l F Cl F Cl n where n is in the range of 1 to 10. The telomers of this invent;on are saturated, low nlolecular weight polymers which are useful for preparing non-flamlllable hydraulic fluids.
Va~^ious methods of prepar;ng chlorotrifluoroethylene ("CTFE") telomers are known in the pr;or art and have been practiced commer-cially for many years. An article by William T. Miller, Jr. et al in Industrial and Engineeriny Chemistry, pages 333-337 (1947), entitled "Low Polymers of Chlorotrifluoroethylene", describes a process for producing low molecular weight polymers of CTFE by polymerization in a solution of chlorofonn using benzoyl peroxide as a polymerization pro-moter. Other solvents disclosed in the reference as being useful for this purpose include carbon tetrachloride and tetrachloroethylene.
The solution is heated in a pressure vessel for 1-3/4 hours at 100C, and tlle unreacted CTFE monomer and chloroform are rernoved by distil-~
.
7 ~ 7 lation, leaving a crude telomer of general formula CHC12(CF~CClF)nCl,which can be further heated and distilled to yield products ranging from a light oil to a semi-solid wax or grease.
Another process for preparing low molecular weight CTFE polymers is described in U.S. Patent No. 2,788,375, issued April 9, 1957. This process comprises reacting CTFE with a saturated brominated compound in the presence of a source of radiation. Suitable brominated com-pounds include l,2-dibromo-2-chlorotri-fluoroethane (CF2BrCClFBr).
The saturated bromopolychlorofluoro compounds obtained by this process lU can then be distilled, and the isolated fractions reacted with chlor-ine to prepare polychlorofluorocompounds. The compounds are predomi-nantly higher molecular weight telomers, i.e. n is greater than 4.
Czechoslovakian Patent No. 201,708, published August 15, 1982, discloses the reaction of CTFE with CBrClFCF2Br using a source of radiation at a temperature of from 20C to 30C to prepare 1,4-dibromo-2,3-dichlorohexafluorobutane and 1,6-dibromo-2,3,5-trichlorononafluorohexane as principal reaction products. These compounds are designated by the following structural formulas:
F F IF F
Br ~C - C - C C Br (1) F Cl Cl F
F F F F F F
BrC - C -C C - C - C - Br (2) F Cl F Cl Cl F
Both compounds (1) and (2) share the common feature of haYing the same end groups, i.e., --CF2Br, as well as ad~acent pairs of -CFCl- groups in the body of the telomer. Telomers having structures such as (1) and (2) are believed to be inherently more unstable and are less easily separated from impurities than the telomers of the present invention.
) rd .~
A Inore recent development in this field is described in a series of articles by Y. Pietrasanta et al entitled Telomerization by Redox Catalysis appeariny in the Eruopean Pol~n__Journal Vol 12 (1976).
This technology involves the reaction of single carbon halogenated 5 telogells, such as CC14 and CC13~r, with CTFE in the presence ~f ben-zoin and a su;table redox catalyst such as ferr;c chloride. The telomer;zation react;on ;s su;tably carried out in acetonitrile wllicll is a collunon sQlvent for the reactants and catalysts. The telomeriza-t;on reaction can be illustrated as follows:
FeC13 CC13X + nCF2-CFCl ~ CC13(CF2CFCl~nX (3) Benzoin where X is chlorine or bromine. The reference further discloses that the use of CC13Br as a telogen results in a lower degree o~ telomeri-zation and a higher proportion of monoaddition product than would occur with the use of CC14.
The redox process bas the advantage of directly preparing low molecular weight products without the necessity of cracking or frac-tionating a higher molecular weight polymer.
A modific~tion of the redox crocess is disclosed in commonlv assigned U.S.Patent 4,808,760, issued ~ebruary 28, 1989, B. Dannels e. al.
In this modification telomers of the structural formula F F F F
Br C - C -C -C- - Br (4) F Cl F Cl In where n is in the range of 1 to 10 are prepared by reacting chlorotrifluoroethylene with 1 2-dibromo-2-chlorotrifluoroethane (CBrClFCF2Br) in the presence of a redox catalvst sYs1:~m~ The redox catalyst system comprises a reducible metal ~alide Selected from the group cons;st;ng of FeC13 FeBr3 CuBr2 CuC12 TiC14 YC13 and NiC12 ~' rd~
and a reducing agent selected from the group consisting of Fe, Ni, Cu, Ti, V and benzoin. This process;has the advantage of being able to prepare CTFE telomers which can be readily separated into relatively pure, stable, low molecular weight isomers, which can be further chlorinated to prepare non-flammable hydraulic fluids.
Although telomers produced according to this latter process represent a significant advance over the prior art, there is still a need to increase the yield of the more desirable low molecular weight species using milder reaction conditions.
SUMMARY OF THE _NVENTION
In accordance with the present invention, distribution of the structural ~ormula is prepared by reacting chlorotrifluoroethylene with l,l-dibromo-l-chlorotrifluoroethane (CF3CClBr2) in the presence of a redox catalyst system. The redox catalyst system comprises a reducible metal compound selected from the group consisting of FeC13, FeBr3, E'e2(SO~)3 CuBr2, CuC12, TiC14, VC13 and NiC12, and a reducing agent selected from the group conSiSting of Fe, Ni, Cu, Ti, V and benzoin. Alternatively, the catalyst system can comprise a metal compound in reduced form without a reducing agent. Suitable reduced metal compounds include FeC12, FeBr2, FeSO4, CuBr and CuCl. The reaction is conducted in a common solvent for the reactants and catalysts, preferably acetonitrile, and the preferred catalyst system is ferric chloride and nickel.
Preferably, the distribution telomers are of the structural formula f~ .
~J
~ 3 ~
F Br F F
l l F C C - C--C ---B r ( 5 ) F Cl F Cl n where n is in the range of 1 to 10.
The telomers may particularly comprise straight-chain telomers of formula CF3CClBr(CF2CFCl)nBr and branched isomers of formula Br(CFClCF2)aCClCF3(CF2CFCl)bBr where n, a and b are in the range of 1 to 10, and the sum of a and b is not more than 10.
The telomerization reaction of the present invention occurs at relatively low temperatures of from about 70C to about 150C, and the reaction produces a relatively high yield o~ low molecular weight species.
` - 4a -~`
J ~ ~
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The telomerization process of the present invention involves the react;on of chlorotrifluoroethylene with l,l-dibromo-l-chlorotri-fluoroethane in a solvent, such as acetonitr;le, ;n the presence of a 5 catalytic amount of a reducible ~letal compound and a suitable metal, or a reduced metal cor.g?ound alone. ~his process can be illustrated as follows:
CF3CClBr + nCF2=CFCl~CF2BrCFCl(CF2CFCl)nBr (6) where n is in the range of 1 to 10.
In reaction (6), K can be a redox catalyst system comprising a reducible metal compound selected frcm the group consisting of FeC13, FeBr3, Fe2(SO4)~9CuBr2, CuC12, TiC14, VC13 and NiC13, and a reducing agent selected from the group cons;sting of iron, nickel, copper, titanium, vanadium and benzoin, where the reducing agent must be capable of reduc;ng the metal compound selected. Typical co~b`in~t:ions of metal halides and reducing agents which are operable include FeC13 or FeBr3 and Fe or Ni, TiC14 and Ti, CuC12 or CuBr2 and Cu, NiC13 and Ni, YC13 and V, and preferably FeC13 and Ni, Mixtures and alloys of the metal reducing agents are also operable in this invention. Alter-natively, K can ccmprise a reduced metal cc~npound without a reducingagent, the reduced metal compound o~ FeC12, FeBr2, FeS04, CuBr and CuCl. Reaction (6) ;s conducted in a common solvent such as ace-tonitr;le, benzonitrile or propionitrile, and preferably acetonitrile.
Reaction (6) results in the preparation of a mixture or distribution of individual telomer species having molecular weights corresponding to n values of from 1 to 10, rather than pure isomers having a discrete structure, i.e. a single n value. Separat;on of the individual telomer species from the mixture is accomplished by distil-lation using procedures well known to those skilled in this art.
~r ~32~ 7 The lighter molecular weight telomers i.e., telomers having an n value of 4 or less, generally predominate in reaction (6). Some of the lighter weight materials, such as the telomer corresponding to an n value of 1, have no known commercial value. ~owever, this telomer can be readily returned or recycled to the telomierzation reaction, and thereby converted into useful telomer products of higher molecular weight, thus increasing the overall efficiency of the reaction. Other telomers are of considerable current interest. For instance, non-flammable hydraulic fluids require an average molecular weight corre-sponding to an n value intermediate between 2 and 4. These fluids canbe produced by first preparing indi~idual stabilized, i.e. chlori-nated, telomers having n values between 2 and 4, and blending these telomers to obtain the desired viscosity. Control of the molecular weight distribution in reaction (6) is there~bre essential since the most desirable products require a narrow molecular weight distribu-tion. This can be achieved by ma;nta;n;n~ the concentration of metal halide (reducible or reduced) in the~r~,a$tion mixture in the range of from about O.Olx to about 2% by weighl't of CTFE, and also maintaining the concentration of reducing agent ~n the reaction m~Xture in an amount of from about 0.5~ to about 3~ by wei~ of CTFE. Following the process of this invention, yi~ of telomer having an n value of 2 to 4 of 50 percent or more can be~chieve~d~
The preferred metal reducing agent is nickel and nickel alloys such as Hastelloy C (Hastelloy is a registered trademark of the Union Carbide Corporation). The metal may be physically present ;n the re-action mixture in a variety of form~, such as a powder, particles of various sizes, wires, plates, or as a cladding material on the inter-nal surface of the reactor. The preferred form is a finely divided powder which is uniformly dispersed in the reaction vessel by means of mechanical agitation, such as in a stirred reactor.
The telomerization reaction is preferably conducted in a stirred reactor under elevated temperature and pressure conditions, with tem-peratures generally ranging from about 70C to about 150C, and pres-sures generally in the range of from about 75 psi to about 450 psi.
~32.1.~.~7 The products of reaction (6) are distinguished by the distribution of -CF2-, -CFCl- and -CBrCl- groups in the telomer chain, and by the presence of one -CF3 and one -CFClBr end group. These telomers can be represented by the following structure:
rF ,1 F - C ~ C - C- Br (5) F Cl F C n The telomers of formula (5) have a bromine atom on the terminal carbon atom, as well as a bromine on the second carbon of the opposite end of the chain. Both of these bromines are sufficiently rPactive to participate in a reinitiation reaction, although the secondary bromine is somewhat less reactive than the primary bromine. Reinitiation of the secondary bromine frequently occurs when FeC13 is selected as the reducible metal compound of choice, and results in a chain that has a trifluoromethyl branch as follows:
Fe~l3 ICF3 CF3CClBr(CF2CFCl)nBr+CF2=CFCl- --rBr(CFClCF2)aCCl(CF2CFCl)bBr (7) where the sum of a and b is not more than 10. Consequently, the pro~ucts of reaction (6) can consist of both straight chain and branched isomers which can be present in the final product in varying degrees.
The follow;ng examples are intended to further illustrate the various embodiments and advantages of the present ;nvention without limiting it thereby. These examples illustrate the preparation of CTFE telomers using various telogens and telomerization processes.
100 9. of CF3CClBr2, 60 9. acetonitrile, 1.5 g. FeC13, and 200 9.
N; powder were placed into the glass liner of a 600 ml. stirred auto-i ~
.
1~2~ 7~
clave . After pressure checking and flushing with N2, 120 9. of CTFE
was added. The autoclave was closed and slowly heated to 120C. The reaction was maintained at this temperature for 4 hours. The maximum pressure reached was 215 psig. As the reaction progressed, an addi-tional 47 9. of CTFE was added from a heated reservoir. The reactorwas then cooled to room temperature, and unreacted CTFE vented off.
Upon opening the autoclave, 123 grams of reaction mixture was obtained which consisted of two liquid phases. This product was washed with dilute HCl and then with water. GC analysis of the washed product indicated that approxima~ely 60 percent of the CF3CClBr2 had reacted. The four (4) carbon telomer made up about 52% of the pro-duct, and appeared to be composed of a single isomer. The six (6) carbon telomer consis~ed of two isomers, one straight chain, the o~her branched. More of the branched isomer than the straight chain isomer was present. Some resuffling of the bromine and chlorine on the telogen was observed. Both CF3CBr3 and CF3CC12Br were found in the product, along with a m;nor amount of each telomer series based upon each of these materials.
100 9. of CF3CClBr2, 60 9. acetonitrile, 3.0 FeC13, and 3.0 g. Fe powder was pl aced i nto the 9l ass 1 i ner of a 600 ml . sti rred autocl ave .
After pressure checking and flushing with N2, 111 9. of CTFE was added. The autoclave was closed and slowly heated to 120C. The re-action was maintained at this temperature for 4 hours. The maximum pressure reached was 200 psig. As the reaction progressed, an addi-tional 59 9. of CTFE was added from a heated reservoir. The reactor was then cooled to room temperature, and unreacted CTFE vented off.
Upon opening the autoclave, 169 grams of reaction mixture was obtained. The product was washed with dilute HCl and then with water, GC analysis of the washed product indicated that approximately 70~ of the CF3CClBr2 had reacted. The four (4) carbon telomer made up about 42X of the product, and appeared to be composed of a single isomer. A
7 ~ ~
larger amount of the resuffled telogens were found in this product than in the product of Example 1.
50 9. of CF3CClBr2, 30 9. acetonitrile, and 2.0 9. FeC12 were placed into the glass liner of a 600 mlO stirred autoclave . After pressure checking and flushing with N2, 112 9. of CTFE was added. The autoclave was closed and slowly heated to 100C. The reaction was maintained at this temperature for 4 hours. The maximum pressure reached was 220 psig. As the reaction progressed7 an add;t;onal 22 g.
of CTFE was added from a heated reservoir. The reactor was then cooled to room temperature, and unreacted CTFE vented off.
Upon open;ng the autoclave, 75 grams of react;on mixture was obtained. This product was washed with dilute HCl and then with water. GC analysis of the washed product ind;cated that approximately 57X of the CF3CClBr2 had reacted. The four (4) carbon telomer made up about 36g of the product~ and appeared to be composed of a single isomer. The straight chain isomer made up the major portion of the six (6) carbon telomer. A smaller amount of resuffled products were present than in the two preceeding examples.
125 9. of CF3CClBr2, 75 9. aceton;tr;le, 7.5 9. Fe2(S04)3 and 5 9. benzo;n were placed into the glass liner of a 600 ml. stirred auto-clave. After pressure checking and flushing with N2, 254 g. of CTFE
was added. The autoclave was closed and slowly heated to 115C. The reaction was maintained at this temperature for 4 hours. The maximum pressure reached was 360 psig. The reactor was then cooled to room temperature, and unreacted CTFE vented off. Upon opening the auto-clave~ 125 grams of reaction mixture was obtained. Th;s crude product was washed with d;lute HCl and then with water. GC analysis of the washed product indicated that approximately 54X of the CF3CClBr2 had reacted. The product was composed of:
1 3 ~d .~ 7 Four (4) Carbon Telomer 39~
Six (6) Carbon Telomer 26%
Eight (8) Carbon Telomer l9X
Ten (10) Carbon Telomer 6g While various embodiments and exemplifications of this invention have been shown and described in the specification, modifications and variations thereof will be readily appreciated by those skilled in the art. It is to be understood, therefore, that the appended claims are intended to cover all such modfîcat;ons and var;ations wh;ch are considered to be within the scope and spirit of the present invention.
Claims (10)
1. A process for preparing a distribution of low molecular weight brominated chlorotrifluoro-ethylene telomers comprising reacting chlorotri-fluoroethylene with CF3CC1Br2 in the presence of a catalyst system comprising a reducible metal compound selected from the group consisting of FeC13, FeBr3, Fe2 ( SO4 )3, CuBr2, CuC12, TiC14, VC13 and NiC13, and a reducing agent capable of reducing the metal compound in the reaction mixture selected from the group consisting of iron, nickel, copper, titanium, vanadium and benzoin, said reaction being conducted in a common solvent for the reactants and catalysts.
2. The process of claim 1 wherein the low molecular weight brominated chlorotrifluoroethylene telomers comprise straight-chain telomers of formula CF3CClBr(CF2CFCl)nBr and branched isomers of formula Br(CFC1CF2)aCC1CF3(CF2CFC1)bBr where n, a and b are in the range of 1 to 10, and the sum of a and b is not more than 10.
3. The process of claim 1 wherein telomers having an n value of between 2 and 4 are present in at least about 50 percent by weight in the reaction product.
4. The process of claim 1, 2 or 3 wherein the common solvent is acetonitrile.
5. The process of claim 4 wherein the catalyst system comprises FeC13 and nickel.
6. The process of claim 5 wherein the FeC13 is present in the reaction mixture in an amount of from about 0.01% to about 2% by weight of chlorotrifluoro-ethylene.
7. The process of claim 1, 2, 3, 5 or 6 wherein the reducing agent ls present in the reaction mixture in an amount of from about 0.5% to about 10% by weight of chlorotrifluoxoethylene.
8. The process of claim l, 2, 3, 5 or 6 wherein the telomerization reaction is conducted at a temperature of from about 70°C to about 150°C and a pressure of from about 75 psi to about 450 psi.
9. A process for preparing a distribution of low molecular weight brominated chlorotrifluoro-ethylene telomers comprising reacting chlorotrifluoroethylene with CF3CC1Br2 in the presence of a catalyst comprising a reduced metal compound selected from the group consisting of FeC12, FeBr2, FeSO4, CuBr and CuC1, said reduction being conducted in a common solvent for the reactants and catalyst.
10. The process of claim 9 wherein the common solvent is acetonitrile.
ll. The process of claim 9 or 10 wherein the catalyst is FeC12.
12. The process of claim 9 or 10 wherein said reacting is conducted at a temperature of from about 70°C to about 150°C and a pressure of from about 75 psi to about 450 psi.
13. The process of claim 11 wherein said reacting is conducted at a temperature of from about 70°C to about 150°C and a pressure of from about 75 psi to about 450 psi.
ll. The process of claim 9 or 10 wherein the catalyst is FeC12.
12. The process of claim 9 or 10 wherein said reacting is conducted at a temperature of from about 70°C to about 150°C and a pressure of from about 75 psi to about 450 psi.
13. The process of claim 11 wherein said reacting is conducted at a temperature of from about 70°C to about 150°C and a pressure of from about 75 psi to about 450 psi.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US11699087A | 1987-11-05 | 1987-11-05 | |
| US116,990 | 1987-11-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1321797C true CA1321797C (en) | 1993-08-31 |
Family
ID=22370438
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000567738A Expired - Fee Related CA1321797C (en) | 1987-11-05 | 1988-05-26 | Process for preparing telomers from chlorotrifluoroethylene and 1,1-dibromo-1- chlorotrifluoroethane |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPH01135733A (en) |
| CA (1) | CA1321797C (en) |
| DE (1) | DE3820934A1 (en) |
| FR (1) | FR2622883A1 (en) |
| GB (1) | GB2211838B (en) |
-
1988
- 1988-05-25 GB GB8812352A patent/GB2211838B/en not_active Expired - Fee Related
- 1988-05-26 CA CA000567738A patent/CA1321797C/en not_active Expired - Fee Related
- 1988-06-13 JP JP63145548A patent/JPH01135733A/en active Pending
- 1988-06-21 DE DE19883820934 patent/DE3820934A1/en not_active Withdrawn
- 1988-06-27 FR FR8808610A patent/FR2622883A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01135733A (en) | 1989-05-29 |
| GB2211838A (en) | 1989-07-12 |
| GB8812352D0 (en) | 1988-06-29 |
| GB2211838B (en) | 1991-08-21 |
| FR2622883A1 (en) | 1989-05-12 |
| DE3820934A1 (en) | 1989-05-18 |
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