PROCESS FOR PRODUCTION OF POLYFLUOROOLEFINS

CROSS-REFERENCE TO RELATED APPLICATION This is a continuation-in-part of Serial No. 595,839 filed October 11, 1990.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

This invention concerns a process for the produc- tion of polyfluoroolefins by the catalytic addition of polyfluoroallylic fluorides to fluoroethylenes. 1:1 and 1:2 Adducts such as £-pentene-2 and £-heptene-3 can be formed selectively and reduced further to dihydro- or trihydropolyfluoroal anes, which are useful as HFC cleaning agents. Higher boiling products, e.g., boiling points above 100°C are useful as solvents and stable liquids, particularly after the double bond has been saturated by hydrogenation, fluorination, or chlorination. 2. Technical Review:

Various catalysts for the addition of poly¬ fluoroallylic fluorides to fluoroethylenes are known. G.G. Belen'kii, E.P. Lur'e, and L.S. German, UDC 66.095.253:547.413, Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow (1975) use SbFs as a catalyst for carrying out the alkylation of the fluoro derivatives of ethylene using perfluoropropylene and 2-H-perfluoropropylene.

Chang-Ming Hu, Hui Liu and Ze-Qi Xu, Reactions of Perchlorofluoro Compounds VI. Rearrangement of Higher Perchlorofluoroolefins and Their Reactions with Nucleo- philes and Electrophiles, teaches the alkali fluoride ion induced formation of a TFE/HFP adduct.

The present invention employs an aluminum halide to catalyze the addition of an allyl fluoride to fluoroethylene.

SUMMARY OF THE INVENTION The present invention provides a process for the manufacture of polyfluoroolefins having at least 5 carbon atoms comprising reacting a first polyfluoro¬ olefin of the structure

where:

R _l is F, Cl, H or R _f ; R2 is F, Cl, H or Rf; R3 is F, Cl, or H;

R _f is a C ₂ to C ₁ 2 perfluoroalkyl, optionally containing 1 H or 1 Cl; R ₄ is F or R _f or where R ₄ together with R2 is -( F2>n~. wherein n is 1, 2 or 3; with a second polyfluoroolefin of structure sCF«CF2 and where

R ₅ is F, H, or Cl; in the presence of a catalyst of the structure AIX3 where X is one or more of F, Cl or Br, provided that X cannot be entirely F.

The invention also concerns olefins of the structures

R _l R2C=C 3CFR ₄

CFR5CF3

and

R _l R2CC (R3) -CFR4

CFR5CF3

or structures derived therefrom by further "migration" of the double bond. By "migration" is meant a shift in the double bond position in the molecule accompanied by relocation of fluorine .

The invention also concerns olefins of the structures :

or rearrangement products resulting from a shift of the double bond. (These later olefins result where R ₄ , together with R2 is -(CF2. ₁ .- in the starting

compound) where n is 1, 2 or 3.

DETAILED PES__ _ _ PTTON OF THE I ENTION

The equation for the addition reaction which is claimed is as follows (where R ₄ is F) :

where i, R _2. *3 and R5 are as defined in the Summary of the Invention. The allylic fluoride may either have the structure shown or be capable of rearranging to that structure by fluorine atom migration in the presence of a catalyst.

The product may also either have the structure shown or a structure resulting from fluorine atom migration. In some cases isome ic products, such as R ₃ R5

R _l R2CFC«=CFCFCF3, are formed.

The catalyst used is of the structure AIX3, where X is one or more of F, Cl or Br, with a proviso that X cannot be entirely F. Active catalyst can be preformed, as in most examples, or can be formed in situ by partial halogen-F exchange with allylic fluoride, as in Examples 9 and 20. Preferred catalysts are AlF _x Cl _y (mixed aluminum halide) , where the total number of atoms of halide, __ plus y equals 3, where x ranges from 0 to about 2.95 and y ranges from 3 to about .05. The AlFχCly, where y is greater than 0, may be prepared by pretreating AICI3 with reactive C-F compounds such as CF3CF ^« CF ₂ , CFCI3 or CHFCI2. ^"

Temperatures range from -20°C to 150°C, depending on the reactivity of the reagents but are preferably in the range of 20 ^β C to 85°C. Pressures may vary from less than 1 atm to over 50 atm, but a preferred range is from 1 atm to 20 atm. Times for batch reactions may vary from about 5 min. to about 2 days depending on batch

size. Times for a continuous reaction may vary from about 1/2 to 120 in. Times for the reaction vary depending upon the identity of the reactants, the temperature, pressure and amount of catalyst. The reaction is best conducted in a liquid phase and can be carried out in several modes; batchwise with addition of reactants and catalyst to a reactor cold and warming to reaction temperature; semibatch by injection of one or both reactants optionally containing catalyst into a vessel containing catalyst and or the other reagent at reaction temperature; or continuous by passing the reactants (preferably at least partly liquified, optionally with catalyst) through a reaction zone, which also optionally contains catalyst. The catalyst must be present in the reactant mixture or the reaction zone but may be present in both places. Reactant mole ratios of allylic fluoride (e.g., HFP) to fluoroolefin (e.g., TFE) can vary from 5:1 to 1:50. Ratios in the 5:1 to 1:1 range are generally used when high yields of one to one adducts are desired. Ratios from 1:1 to 1:50 are used when multiple additions of fluoroethylene are desired to form one-to-two and higher adducts, especially when the fluoroolefin is tetrafluoroethylene (TFE) . Catalyst loadings in a batch reaction can be from about 0.5 to about 20 wt-%, preferably 2-8 wt-%, of the total charge of reactants.

Solvents are generally not essential, but a liquid phase is usef l to facilitate reaction" ^" -of low-boiling materials that are not condensed under reaction conditions. Solvents are also useful for controlling any initial exotherm when a catalyst, such as aluminum chloride, is used in a large scale reaction. Relatively inert materials which may be used as solvents include hexafluorobenzene, E-n-hexane, CICF2CF2CI, SO2CIF, CF3CF2CHCI2, CICF2CF2CHFCI, CF3CHFCHFCF2CF3,

CF3CHFCH2CF2CF3, CF3CH2CHFCF2CF3, CICF2CFCI2, CF3CCI3, CF3CC1 ₂ CF3, CF3CHCI2, £-l,2-dimethylcyclobutane, CCI2-CCI2, CCI2-CHCI, CF ₃ CF ₂ CF2θ[CF(CF3)CF ₂ 0] _n CHFCF3- (CF ₃ )2C-CFCF2CF3, (CF3)2CFCF-CFCF2 , £-pentene-2 , F-heptene-3, F-heptene-2, and C _n F _2n . where n is 9 or greater. Highly fluorinated olefins are preferred solvents and perfluoroolefins, CnF _2n , wherein n is 5 or greater are most preferred. £-ρentene-2, for example, is especially preferred for the reaction in which it is also the product, i.e. the condensation of CF3CF-CF2 with CF ₂ *CF ₂ , since the reaction mixture can be over 95% C5F ₁₀ , and therefore easily purified. Selectivity in this procedure is high because CF3CF«CF is much more reactive than CF3CF»CFCF ₂ CF3 and, when present, reacts with CF ₂ ^β CF ₂ , almost exclusively.

Table I shows various examples and reaction conditions. It should be noted that some of the entries in Table I, in which large excesses of tetrafluoro- ethylene (TFE) over hexafluoropropene (HFP) were used, resulted in appreciable condensation of TFE with itself to yield even numbers of carbon atoms in product fluoro- olefins. Also, as multiple additions of TFE to HFP increase in number, branching in the product olefins becomes more pronounced. Thus, C5F ₁ 0 and C7F ₁₄ are linear products, C9F3. ₈ is mainly linear, C ₃ . ₁ F22 and higher have increasing amounts of structures of the type (Rf)2θCFRf. These mixtures of high-boiling liquids are converted to even higher boiling, stable liquids by hydrogenation, chlorination or fluorination. The synthesis described herein can be used to form 1:1 and 1:2 adducts such as £-pentene-2 (CF3CF«=CFCF2CF3) and £-heptene-3/F-heptene-2 mixtures which can be reduced to form HFC cleaning agents. It can also be used to form higher adducts useful as a source of unreactive solvents, vapor degreasing agents, and stable

liquids by chlorination, fluorination or hydrogenation of the double bond.

EXAMPLES Catalyst preparation - 1CJ3+CF3CF-CF2

A slurry of 100 g (0.75 mol) of AICI3 (Aldrich,

99.9% pure) in 100 mL of CCI4 was stirred under nitrogen under a -80°C condenser while 20 g (0.13 mol) of

CF3CF ^« CF ₂ was bled in over 1.75 hr. Some unreacted hexafluoropropene, which was present at the end and caused the temperature to drop to 5°C, was bled off, and the mixture was warmed to 0°C. Another addition of 11 g (0.07 mol) of CF3CF«CF ₂ over a 1 hr period resulted in an exother to 50°C. Continued slow addition at 50-65°C of 42 g (0.28 mol) of CF3CF-CF2 finally resulted in persistent reflux of unreacted CF3CF ^« CF2« The reaction mixture was transferred to a dry box, where it was filtered. The filter cake was rinsed with 2 X 50 mL of dry CCI ₄ , then dried under vacuum to afford 84.7 g of greenish, free-flowing powder.

Catalyst Preparation - AIC ₃ +CFCI ₃

500 g (3.75 mol) of AICI3 (Aldrich-99% pure) was stirred mechanically under 2 in a r.b. flask fitted with a -80°C condenser while 1750 mL (-2625 g, 19 mol) of CFCI3 was added over a 1.5-hr period. Reaction is very exothermic in the early stages, so addition of CFCI3 was slow at first in order to keep the temperature below 65°C, then rapid. The resulting suspension was stirred an additional 3 hrs while volatiles (CF2CI2) were allowed to escape through the warmed condenser. The condenser was then replaced with a simple stillhead, and most of the CCI ₄ was distilled under reduced pressure [mainly bp 38°C (200 mm)] . Finally, the last

traces of volatiles were removed by warming the residual solid to 30-35 ^e C at 0.05 mm.

The sealed r.b. flask was transferred to a dry box and unloaded into a Teflon® FEP bottle; 340 g of rather finely divided yellow-green solid. Portions of the catalyst were weighed out in the dry box as needed and taken out in plastic bottles with pressure-seal caps.

Analysis for fluorine of the products from preparation of this type indicated the composition to be AIF2.9CI0.1, AlFxCly; X - 2.8-2.9, Cl - 0.2-0.1.

EXflMPLE 1 A 400-mL metal tube charged with 16.4 g of fluoridated AICI3 (AICI ₃ + CFCI3), 100 g (0.5 mol) of l,l,2-trichloro-3,3,3-trifluoropropene, and 50 g

(0.50 mol) of tetrafluoroethene was agitated at 25 ^C C for 1.5 hr . Fractionation of the liquid product mixture gave 25.4 g (25%) of recovered CF3CCI-CCI2, then 42.3 g (38% yield) pf £-1, 1, 2-trichloropentene-l, bp 63-66°C (100 mm) , identified by IR, NMR and GC/MS . Further fractionation afforded 23.3 g (15%) of an isomeric mixture of £-l, l, 2-tetrachloropentene-l and F-l, 1, 1-2- tetrachloropentene-2, bp 86-89°C (100 mm) , identity indicated by IR, NMR and GC/MS . Some higher boiling 2 : 1 adducts were also present .

The equation for the reaction is shown below:

A1F.CL CF ₃ CC1=CC1 ₂ + CF ₂ =CF ₂ Z_____»__ CF ₃ tF ₂ CF ₂ CCl=CC_ ₂

+ CF ₃ CF ₂ CFC1CC1=CC1 ₂ + CF ₃ CF ₂ CF=CClCC- ₃

EXAMPLE 2

A 400-mL metal tube charged at -20 ^β C with 8.0 g of AIF2.8CI0.2 (prepared from AICI3 + CFCI3), 75 g (0.50

mol) of hexafluoropropene (HFP), and 50 g (0.50 mol) of tetrafluoroethylene (TFE) was shaken for 30 min. while the temperature rose quickly to 20 ^β C and the pressure dropped to 8 psi. Distillation of the product afforded 88.0 g (70%) of £-pentene-2, b.p. 23-26 ^β C, identified by IR, NMR and GC/MS. NMR showed the product to be 89% trans-isomer and 11% cis-isomer.

EXAMPLE 3 Reaction of CF3CF«CF ₂ /CF ₂ ^« CF2 in 1:2 Ratio

A 400-mL metal tube charged cold with 3 g of AlF _x Cly (fluorinated aluminum chloride catalyst prepared by treating aluminum chloride with CFCI3), 40 g 0.27 mol) of hexafluoropropene, and 50 g (0.50 mol) of tetrafluoroethylene was agitated at 25°C for 2 hr and at 80°C for 4 hr. Analysis of the liquid product, 73 g, by GC and MS indicated the presence of 28.2 g (42%) of perfluoro-pentene-2, 42.2 g (48%) of perfluoroheptene isomers, 2.7 g (4%) of perfluorononene isomers, <0.7 g (1%) of C ₃ . ₁ F22 isomers, and traces of higher oligomers, with very small amounts of perfluorohexene and perfluorooctene also detected. Fractionation afforded 21.9 g (32%) of perfluoropentene-2, bp 24-26 ^p C, followed by 34.1 g (39%) of perfluoroheptenes, bp 69.5-71 ^β C. Analysis of a center cut, bp 70.9 ^β C, by IR and NMR showed the major component to be trans-perfluoro- heptene-3 with only small amounts of other isomers present. Continued fractionation afforded 1.2 g (2%) of perfluorononenes, bp 66-68 ^β C (150 mm), shown by IR and NMR to consist mainly of trans-perfluorononene-4 and trans-perfluorononene-3.

EXAMPLE A

Reaction of CF ₃ CF-CF2/CF2-CF2 in 1:4 Ratio A 400-mL tube charged cold with 5.0 g of AlF _x Cl _y , 40 g (0.27 mol) of hexafluoropropene, and 50 g (0.50 mol) of tetrafluoroethylene was shaken at 25°C for 30 min. while the pressure dropped to 0 psi. Another 50 g (0.50 mol) of tetrafluoroethylene was added, and the mixture was agitated for 4 br at 25°C while the pressure again fell to 0 psi. Analysis of the liquid product, 122 g, by GC and MS indicated the presence of 34.5 g (37% yield) of perfluoroheptenes, 59.0 g (49% of perfluorononenes, 22.2 g (15%) of perfluoroundecenes, and 2.0 g (1%) of perfluorotridecenes, with 0.5-1% of perfluoroolefins having even numbers of carbon atoms CβFi∑, C8F16 and C ₁₀ F20 also detected. Distillation afforded a series of fractions, bp 66°C (1 atm) to 66°C (18 mm), which were characterized by GC, IR and NMR analysis. Product boiling at 71-72 ^β C was shown to consist of straight-chain trans-perfluoroheptene-3 and trans- and cis-perfluoroheptene-2, with very small amounts of branched olefins (e.g., CF ₃ CF2C(CF3> « CFCF2CF3) present. Product with bp 74-80 ^β C (200 mm) was found to be mainly staight-chain trans-perfluorononene-4 and tra_-S-perfluorononene-3, with perhaps 50% of branched perfluorononenes present in a fraction bp 74°C (200 mm) dropping to about 5% branched olefins in fractions bp 76-80 ^β C (200 mm) . The mixed perfluoroundecenes with bp 70-77°C (50 mm) were shown to be mainly branched structures of the type (R _f ) ₂ OCFR _f , with linear olefins R _f CF«CFR _f as minor components.

EXAMPLE 20

Reaction of Equimolar CF3CF«CF2 with CF2«CF2 with AICI ₃ Catalyst in CCl ₂ ^« CCl2 Solvent

A tube charged cold with 5.0 g of aluminum chloride, 100 mL of tetrachloroethylene, 759 (0.50 mol) of hexafluoropropene, and 50 g (0.50 mol) of tetrafluoroethylene was shaken at 25-30 ^β C for 4 hr while the pressure dropped to 69 psi. The reaction mixture was then heated at 60°C for 10 hr while the pressure fell to 45 psi. The liquid product, two phases, was distilled to give a foreshot of 4 mL followed by 58.4 g (47%) of perfluoroρentene-2, bp 10-25 ^β C, nearly 100% pure by GC.

Tetrachloroethylene is a preferred solvent because of its availability, relative inertness under reaction conditions, and ease of separation from low boiling 1:1 and 1:2 adducts.

EXAMPLE 21 Addition of CF2-CF2 to £-Cyclopentene

A 1-L. stirred autoclave was charged with 30 g of AlFxCly and 118 g (0.56 mol) of £-cyclopentene. Tetrafluoroethylene (47.3 g, 0.47 mol) was pressured in and the vessel was heated slowly with stirring to 80°C, where reaction rate was appreciable. Tetrafluoro¬ ethylene was added in portions at 80°C until a total of

114.4 g (1.14 mol) had been added over 14 hr. Reaction was continued another 7 hr. Volatiles obtained by heating the crude reaction product at 100°C (0.3 mm) were 122.6 g of liquid. Fractionation afforded 96.2 g (55%) of £-l-ethylcyclopentene, bp 64-66°C, identified by IR and NMR analysis.

EXAMPLE 22 Addition of CF ₂ -CF ₂ to F(CF ₂ )4CH-CH(CF2)4F

A metal tube charged with 5 g of AlF _x Cl _y , 50 g (0.50 mol) of CF2-CF2, and 139 g (0.30 mol) of F(CF ₂ )4CH-CH(CF2)4F was shaken at 25°C for 17 hr. The reaction mixture was filtered and distilled to give 90.5 g (54%) of 1:1 adducts, bp 60-63 ^β C (20 mm), identified by GC/MS. The major isomer, about 95% of the total, was shown to be CF3CF2CF2CF-CHCH(CF2CF3)CF2CF ₂ CF ₂ CF3 by IR and NMR analysis.

EXAMPLE 23 Use of CF ₃ CF«CFCF ₂ CF3 as Solvent A 400-mL metal tube charged with 5.0 g AlFjςCly,

49.5 g of CF3CF«CFCF2CF ₃ , 75 g (0.50 mol) of CF3CF-CF2, and 50 g (0.50 mol) of CF2-CF2 was agitated as it warmed over 0 ^β C. From a peak pressure (115 psig) at 16°C, the pressure fell rapidly to 9 psig, while a slight exotherm carried the temperature to 28°C before subsiding to 22°C, all in 1 hr. Heating at 60°C produced no further sign of reaction. GC analysis of the crude product, 169 g, indicated that 110.1 g (88%) of C5F ₁₀ had been formed. Only small amounts of by-products such as hexafluoro- propene dimer were present.

Example Cat (wt. %) Reactants (molar ratio) (Time (hr.)) Products (% yield)

AlF _x Cly (10) CF ₃ CCI-CCI2 + CF ₂ -CF ₂ (1:1) 25" (1.5) 166-6 F(CF ₂ ) ₃ CC1-CC1 ₂ (38%); r(CF ₂ )2CFClCCl-CCl2 + (CF2)2CF-CClCCl3 (151)

AlF„Cly (6) CF3CF-CF2 + CF ₂ -CF ₂ (1:1) 0-20 ^β (0.5) down to 8 89:11 trans/ciβ-F CF2)2C

(70%), trace HFP dlmer

AlF _x Cl _y (3) CF3CF-CF2 + CF2-CF2 (1:2) 25 ^β (2), 80 ^β (4) 266-68, 96-50 P(CF ₂ )2CF-CFCF ₃ (321), (CF ₂ ) 3CF-CF (CF ₂ ) 2* (391)

F(C 2)5C -C CF2>2P + others (2%)

AlF _x Cly (5) CF3CF-CF2 + Cr ₂ -CF2 (1:4) 11-25* (0.5, 4) 138-0, 173-0 C ₇ Fιι (37%), C ₉ Fii (491), (2 TFE additions) C11F22 (15%), small amoun other olefins and solid polymer

AlF _x Cly (3) CF ₃ C -CrCF2CF ₃ +CF2-CF2 (1:1) 35-40° (4) 40-60 C ₇ F ₁₄ (78%), C9F18 (6%) Carried out semibatch with TFE added continuously.

Temp (°C) Pressure Range

Example Cat (wt. %) Reactants (molar ratio) (Time (hr.)) <p ^a *q> Products (% yield)

AlF _x Cly (5) CF ₃ CH-CH2 + CF2-CF2 (1:1) 25° (2) ,60" (4) 230-400 F(CF ₂ ) ₃ CH-CH ₂ (low, mainl CF ₃ CH-CH ₂ dlmers

AlFxCly (4) 80° (3) 334-19 1:1 adducts (36%), 2:1 adducts (32%)

AlFχCly (3) F ₃ + CF2-CF2 80 ^β (2) 347-34 F(CF ₂ ) ₃ CC1-CC1CF ₃ (48%),

(0.8:1) F(C 2 ₃ CC1-CC1(C 2)3F (20

AICI3 (2) CF ₃ CF-CF2 ^■ * ^• CF ₂ -CF ₂ (1:1) 25° (0.5) ,40° (2) 240, down to 34 r(CF ₂ ) ₂ CF-CFCF3 (47), sma amts. high boilers

10 AlF _κ Cly (2) CF ₃ CF-CF2 + CF ₂ -CF ₂ (1:1) 12-26° (4) 203-35 F(CF ₂ )2CF-CFCF ₃ (69%)

11 AlFχCly (4) CF ₃ CH-CF ₂ + CF2-CF2 (1:1) 25° (3.5) 153-0 CF ₃ CH-CFCF2CF3 (80%),

F (CF ₂ ) ₂ CF-CH (CF ₂ ) ₃ F (low) plus others

Temp CO Pressure Range

Example Cat (wt. %) Reactants (molar ratio) (Time (hr.)) t ^p si ^q * Products (% yield

12 AlFχCly (4) CF ₃ CF-CF ₂ + CF ₂ -CFC1 (1:1) 25° (4) 85-18 CF3CF2CF-CCICF3 (36%), a with CF ₃ CF ₂ CC1-CC1CF ₃ , (CF ₂ ) ₃ CF-CC1CFCF ₃ , F(CF2).CC1-CC1CF ₃ (18%) and others

13 AlFχCly (4) CF ₃ CF-CF ₂ + CF2-CF2 (1:10) 4-25° (3, 18) 152-19, 240-1 C7F1 CFU, CHF22 end

(2 TFE additions) Cι ₃ 2β as major series, ^c §*_Lβ» C10F 0, and solid polymer also formed

14 AlFχCly (5) CF ₃ CF-CF2 + CF2-CF2 (1:30) 25° (4),50* (1) 165-21, 179-44 C ₆ ι ₂ to Cι ₅ r ₃₀ liquids (2 TFE additions) poly (TFE)

15 AlFχCly (6) C7F14 isomers ^■ * ^• CF ₂ -CF ₂ 25° (10),50* (6) 198-0, constant _G Fi2 (1%), C ₇ Fn (1%),

(1:7) (16%), C ₉ F _lβ (32%), C1 ₀ F (16%), CnF ₂₂ (30%), Cι ₂ (3%), C13F26 (2%) plus polymer

Temp CO Pressure Range

Example Cat (wt. %) . Reactants (molar ratio) (Time (hr.)) (psig) Products (% yield

16 AlFxCly (5) (CF ₃ ) ₂ CFCF-CFCF ₃ + 10-25° (6) 160-0 1:1 adducts (32%),

CF ₂ -CF ₂ (1:3) 2:1 (54%), 3:1 (10%)

17 AlFxCly (6) CF ₃ CF-CF2 (CeFβ solvent) 25° (4) , 85° (10) (no readings) (CF ₃ ) ₂ C-CFCF ₂ CF3 (20%), (CF ₃ ) ₂ CFCF-CFCF ₃ (2%)

18 AlFχCly (5) (CF ₃ ) 2C-CFCF ₂ CF ₃ 4 CF ₂ -CF ₂ 16-25° (8) 178-0 CF ₃ CF ₂ CF2C(CF ₃ )-CFCF2CF ₃

(1 :3) (2%), considerable poly(

19 AlBr ₃ (7) CF ₃ CF-CF2 + CF2-CF2 25-80° (8) 220-515 C5FIO (1*» + C7l"i (1%)

(1 : 1)

20 A1C1 ₃ (4) CF2CF-CF2 + CF2-CF2 25-30° (4) see text CF2CF-CFCF2CF3 (47%)

(1 : 1) 60° (10)

21 AlFχCly (13) F-cyclopentene, CF ₂ -CF ₂ (1 :2) 80° (21) no readings F-1-βth lcyclopβntenβ (5

22 AlFxCly (2.6) F (CF ₂ ) «CH-CH (CF ₂ ) F + 25° (17) no readings CF ₃ (CF2) 2CF-CHCH(CF ₂ CF ₃ ) (

CF2-CF2 (3: 5) + isomers (54%)

23 AlFχCly (4) CF ₃ CF-CF ₂ '+ CF ₂ -CF ₂ (1:1) see text 115 psi C5F10 (88%) -> 9

Although preferred embodiments of the invention have been described hereinabove, it is to be understood that there is no intention to limit the invention to the precise constructions herein disclosed, and it is to be further understood that the right is reserved to all changes coming within the scope of the invention as defined by the appended claims.