Background of the Invention

The invention relates to a cost effective and convenient process for the manufacture of fluorinated olefins of the formula RCF2CH=CH2 where R is C _x ClyF ₂ and y + z = 2x + 1 which may be used as starting materials for the manufacture of hydrofluorocarbons. The invention is also directed to a practical process for converting these olefins to hydrofluorocarbons via catalyzed fluorination with hydrogen fluoride. The hydrofluorocarbons produced via this process have utility, among other things, as solvents.

Traditionally, chlorofiuorocarbons (CFCs) like trichlorofluoromethane (CFC-11), dichlorodifiuoromethane (CFC-12) and 1 ,1,2-trichloro-1 ,2,2-trifluoroethane (CFC-113) have been used as solvents, refrigerants, blowing agents and diluents for gaseous sterilization. These materials, however, are suspect since they are believed to contribute to the stratospheric ozone depletion problem. The fluorocarbon industry has therefore focused its attention on developing stratospherically safer alternatives to these materials. Hydrofluorocarbons (HFC's) like CF3CF2CH2CH2F (HFC-356mcfq), which has been identified as a solvent, are candidate replacement materials since they have no ozone depletion potential, contribute negligibly to global warming and offer substantially the same performance advantages such as nonflammability. As a result, methods for the manufacture of these materials need to be developed.

A few methods for the manufacture of compounds of the formula RfCH=CH2 where Rf is C _n F2n + 1 are known in the art. See, e.g., U.S. Patent 4,058,573 and Brace et.al., Effect of a perfluoroalkyl group on the elimination and substitution reactions of two homologous series of perfluoroalkyl-substituted iodoalkanes, 49 J. Org. Chem., 2361 (1984). These references disclose the addition of a perfluoroalkyl iodide to

ethylene to yield RfCH2CH2l, followed by dehydroiodination to provide the olefin, RfCH=CH2- This method is convenient only for the preparation of small quantities of materials because of the prohibitively high cost of the perfluoroalkyl iodide.

U.S. Patents 2,889,379 ('379 patent), 4,798,818 ('818 patent), and 4,465,786 (786 patent) disclose the preparation of CF3CH=CH2 by the catalyzed vapor phase fluorination of various halogen-containing C3 compounds such as CCI3CH2CH2CI. These references however, do not teach or suggest that higher molecular weight homologs can be prepared by this method.

The halogen exchange in the precursors to the fluorinated olefins of our invention is dissimilar to the halogen exchange reported in these references. That is, the references are replacing the chlorine in a -CCI3. group with fluorine while we are replacing the chlorine in a -CF2CCI2CH2 group with fluorine. U.S. Patent 4,078,007 discloses the liquid phase antimony pentachloride catalyzed fluorination with HF of CCI3CH2CH2CI (the same compounds used in the '379, '818 and 786 patents) to provide CF3CH2CH2CI at reaction temperatures of about 85°C. However, the liquid phase antimony pentachloride catalyzed fluorination with HF of CF3CCI2CH2CH2CI (a precursor of the fluorinated olefins of our invention) even at substantially higher reaction temperatures failed to result in even modest fluorination. That is, of the product recovered, 97% was starting material. See Comparative Examples 1 and 2.

As far as methods for the synthesis of HFC's from fluorinated olefins is concerned, Henne et al., Influence of a CF3 group on an adjacent double bond, 72 J. Am. Chem. Soc, 3369 (1950) report that the CF3 group in CF3CH=CH2 adversely affects the rate of addition of acids, HX where X is Br or Cl, to the carbon-carbon double bond. That is, Lewis acid catalysts and elevated temperatures are required to force these additions and even then modest yields and/or conversions may be obtained.

We have discovered: 1 ) a novel method for the production of

fluorinated olefins and 2) a novel method for the manufacture of various HFC's using these fluorinated olefins as starting materials which overcome the drawbacks of the prior art processes discussed above.

Description of the Invention

This invention relates, in part, to a cost effective and convenient process for the manufacture of compounds of the formula where R is C _x Cl _y F _z and y + z = 2x + 1. Preferably, the invention relates to preparation of compounds of the formula RCF2CH=CH2 where R is C _x ClyF _z and where x < 4 and y < 2 such as CF3CF2CH=CH2, CF3CF ₂ CF2CH=CH ₂ , and (CF ₃ )CFCF ₂ CH=CH2 comprising:

a) reacting a compound of the formula RCX _a F _D ; where R = ^c m ^x n ^F o. m < 4, n < 2, m + o = 2m + 1 , X = Cl or Br, a = 2 - 3, and b = 0 - 1 , with ethylene in the presence of an addition catalyst and a solvent under conditions sufficient to produce a compound of the formula RCX _a _ <|FbCH2CH2X where X = Cl or Br, a = 2 - 3, b = 0 - 1 and a + b = 3;

b) reacting a compound of the formula RC _a _ ^< ιF _D CH2CH2X where X = Cl or Br, a = 2 - 3, b = 0 - 1 and a + b = 3r with hydrogen fluoride in the presence of a fluorination catalyst under conditions sufficient to produce a compound of the formula RCF2CH=CH2 where R is C _x Cl _y F ₂ where y + z = 2x + 1; and

c) recovering a compound of the formula RCF2CH=CH2 where R is C _x ClyF _z and y + z = 2x + 1.

The starting material for the addition reaction, i.e., ethylene and compounds of the formula RCX _a F _D ; where R = C _m X _n F ₀ , m < 4, n < 2, m + o = 2m + 1, X = Cl or Br, a = 2 - 3, b = 0 - 1, and a + b = 3 are commercially available from AlliedSignal Inc. or other domestic chemical manufacturers. Alternately, they may be synthesized by methods well known in the art. Suitable halogenated starting materials include, but are not limited to,: CF3CCI3, CF ₂ CICFCl2, CF ₃ CF2CCl3, CICF ₂ CF ₂ CCI ₃ ,

CCI3CF2CCI3, CF ₂ BrCF ₂ CFBr2, CF3CCI2CF2CCI3,

(CF ₃ )(CF ₂ CI)CFCCl3, (CF ₃ )2CFCCI _3l CICF ₂ CFCICF ₂ CFCI ₂ . Preferred starting materials include: CF3CCI3, CF2CICFCI2, CICF2CF2CCI3 and CCI3CF2CCI3.

Any commercially available catalyst known in the art to be useful in catalyzing the addition of halocarbons to olefins may be employed. Suitable addition catalysts include, but are not limited to, copper (I) salts such as cuprous chloride and cuprous iodide, iron (II) salts such as ferrous chloride and ferrous acetate, and metal carbonyls such as iron carbonyi and cobalt carbonyl. Cuprous chloride is preferred. Optionally, any well known co-catalyst useful in catalyzing the addition of halocarbons to olefins may be employed in the reaction. Suitable addition co-catalysts include aliphatic or aromatic amines such as pyridine and diethylamine.

Any inert solvent which can dissolve the catalyst and is miscible with the halocarbon may be used in the reaction. Suitable solvents include, but are not limited to, commercially available low molecular weight nitriles such as acetonitrile and propionitriie, low molecular weight alcohols such as tertiary butanol and isopropaπol, and amides such as dimethylformamide. Acetonitrile is preferred because of ease of handling and stability.

The temperature at which the addition reaction is conducted and the period of reaction will depend on the starting material and catalyst used. One of ordinary skill in the art can readily optimize the conditions of the reaction without undue experimentation to get the claimed results but the temperature will generally be in the range of from about 50 to about 150°C for a period of from about 8 - 72 hours. When the starting material is one of the preferred compounds and the catalyst is cuprous chloride, the reaction may be conducted at a temperature of from about 80 - 150°C for a period of from about 24 to about 48 hours. Preferably, such a reaction would be conducted at a temperature of from about 125 to about 150°C for a period of from about 8 to about 30 hours.

Pressure is not critical.

Preferably the reaction is conducted in an apparatus made of corrosion resistant materials such as Teflon and glass.

Preferably, the addition product is recovered from by-products, solvent and catalyst prior to the fluorination reaction to substantially eliminate the production of by-products in the fluorination step. Preferably, the addition product should be about 95% pure. More preferably, the addition product should be about 98 % pure. The addition product may be recovered by any means well known in the art such as distillation and extraction. See, for example, Examples 1 and 2 below.

Compounds of the formula RCX _a . _η FbCH2CH2X where X = Cl or Br , a = 2 - 3, and b = 0 - 1 , a + b = 3 are the starting material for the fluorination reaction. They may be prepared as discussed above.

Preferred starting materials include CF3CCI2CH2CH2CI,

CICF ₂ CFCICH2CH ₂ CI, and CICF2CF2CCI2CH2CH2CI.

Commercially available hydrogen fluoride (HF) may be used in the fluorination reaction. Preferably, the HF is anhydrous. By "anhydrous" we mean that the HF contains less than about 1 wt% water and preferably contains less than about 0.5 wt% water and more preferably contains less than about 0.02 wt% water. HF suitable for use in the reaction may be purchased from AlliedSignal Inc. of Morristown, NJ.

Any well known vapor phase fluorination catalyst may be used in the fluorination reaction. Suitable fluorination catalysts include the following catalysts and mixtures thereof: metal oxides such as chrome (III) oxide, supported metal oxides such as chrome (III) oxide supported on aluminum oxide or carbon and supported metal halides such as cobalt (II) chloride and nickel (II) chloride supported on carbon, aluminum oxide, aluminum fluoride, or a mixture of such support materials, such as a mixture of Cr2θ3 and AI2O3. Chrome (III) oxide is preferred due to its level of reactivity and commercial availability. Suitable chrome (III) oxide catalysts may be purchased from Mallinckrodt Specialty Chemicals Co. of

St. Louis, MO.

Over time, the catalyst activity may diminish. In the case where such deactivation is caused by coking, the catalyst may be reactivated, for example, by heating in a stream of air or oxygen. If chrome (III) oxide is the catalyst, following reactivation, the catalyst is preferably pretreated according to the process set forth in Example 3a.

One of ordinary skill in the art can readily optimize the conditions of the reaction without undue experimentation to get the claimed results. Generally, the organics, HF and fluorination catalyst are reacted at a temperature in the range of from about 150 to about 350 ^β C, preferably, from about 200 to about 275°C and most preferably from about 225 to about 250°C with a contact time of, for example, about 0.1 to about 240 seconds, preferably from about 1 to about 100 seconds and most preferably from about 5 to about 50 seconds. For purposes of this invention, contact time shall mean the time required for the gaseous reactants to pass through the catalyst bed assuming that the catalyst bed is 100% void.

The molar ratio of HF to organics will depend on the number of nonfluorine halogens in the starting material. Generally, the mole ratio of HF to organics will be from about 1 to about 30 moles HF per mole of nonfluorine halogen present. See Examples 3 - 6.

Pressure is not critical. Atmospheric and super atmospheric pressure are the most convenient and are therefore preferred. In particular, high reaction pressure is desirable because it makes separation of the HF from HCI easier.

The reaction is preferably conducted in an apparatus made of corrosion resistant material such as Inconel or Monel.

In another embodiment, the invention relates to a process for preparing HFC's comprising:

1 ) reacting a compound of the formula RCF2CH=CH2 where R is C _x ClyF _z and y + z = 2x + 1 with hydrogen fluoride in the presence of an antimony (V) haiide catalyst under conditions sufficient to produce a compound of the formula RCF2CH2CH2F where R is C _x ClyF _z; and y + z = 2x + 1 • and

2) recovering a compound of the formula RCF2CH2CH2F where R is C _x Cl _y F _z and y + z = 2x + 1.

The fluorinated olefin starting material is selected based upon the desired HFC to be produced. For example, if one wanted to produce CF3CF2CH2CH2F, then one would use CF3CF2CH=CH2 as the starting material.

Any water in the HF will react with and deactivate the antimony (V) haiide catalyst. Therefore, substantially anhydrous HF is preferred. By "substantially anhydrous" we mean that the HF contains less than about 0.05wt% water and preferably contains less than about 0.02 wt% water. However, one of ordinary skill in the art will appreciate that the presence of water in the catalyst can be compensated for by increasing the amount of catalyst used. HF suitable for use in the reaction may be purchased from AlliedSignal Inc. of Morristown, NJ.

Any antimony (V) haiide, antimony (V) mixed haiide, or mixtures of antimony (V) haiide catalysts may be used in the fluorination reaction. Examples of antimony (V) haiide catalysts include antimony pentachloride and antimony pentafluoride. Examples of antimony (V) mixed halides include SbCl2F3 and SbBr2Cl3. Examples of mixtures of antimony (V) haiide catalysts include a mixture of antimony pentachloride and antimony pentafluoride. Antimony pentachloride is preferred because of its low cost and availability.

The temperature at which the organics, hydrogen fluoride and fluorination catalyst are reacted is critical. If the temperature is too low (i.e., <-20°C), the desired reaction is very slow, but if it is too high (i.e., >20°C) undesirable side reactions occur, which include the reverse

reaction, which reduces yield. Thus, it is preferred to run the reaction at a temperature of from about -20 to about 20°C. A reaction temperature of from about -10 to about 10°C is more preferred and a reaction temperature of from about -5 to about 5°C is most preferred.

The stoichiometric molar ratio of HF to organics in the fluorination reaction is 1:1. However, in order to dissolve the catalyst and control reaction temperature, the HF is preferably used in excess i.e., e.g., from about 10 - 20:1 HF:organics.

Atmospheric or superatmospheric pressure is preferred.

The reaction is preferably conducted in an apparatus made of corrosion resistant material such as Inconel, Monei or Teflon.

Example 1

Addition of CF CF7CCK to ethylene to produce CF^CF CChCH CH CI A Teflon-lined autoclave was charged with 137 g. of cold CF3CF2CCI3 , 1 g Cul, 20 mL cold CH3CN, and 3 mL pyridine, and evacuated briefly. Ethylene (18.3 g) was then charged and the contents heated to 137°C for 6 h. After allowing the contents to cool, the volatiles were vented, and the contents were poured into 100 mL 1 N HCI. The organic layer was washed with cold water (100 mL) and dried (CaCl2). Distillation provided 87 g of a colorless liquid which was identified spectroscopically as CF3CF2CCI2CH2CH2CI (bp 71-73°C at 75-6 mm Hg). ¹ H NMR: equal intensity triplets at δ 3.93 and 2.82; ¹⁹ F NMR: -77.3 (3 F) and -117.5 (2 F) ppm; IR: strong bands at 1225, 1185, 1160 cm ^'1 . Gas chromatography determined that the product was 99.6% pure.

Example 2

Addition of CF CCh to ethylene to produce CF^CCbC^CHoCI. A 600 mL stirred Monel autoclave was charged with 30 mL CH3CN, 3 mL pyridine, 1 g Cul, and 199.6 CF3CCI3. The contents were cooled to -29 °

C, the autoclave briefly evacuated, and charged with 24.4 g ethylene. The

contents were then heated to 135-145 °C for 22 h. After cooling the contents, the volatiles (unreacted ethylene) were vented. The residue was diluted with 300 mL water, and extracted with 50 mL CH2CI2. The organic layer was then washed twice with 50 mL 5 % aqueous HCI, twice with 50 mL 5 % NaOH, twice with 50 mL water and finally dried (CaCl2). Distillation at 145 mm Hg gave 80 g (58 % yield) of a colorless liquid which was identified spectroscopically as CF3CCI2CH2CH2CI (bp 102- 103 °C). ¹ H NMR: equal intensity triplets at δ 3.9 and 2.77; ¹⁹ F NMR: -81 (s) ppm; IR: strong bands characteristic of CF3CCI2CH2- grouping at 1255, 1210, and 1180cm ^"1 . Gas chromatography determined that the product was 99% pure. CF3CCI2CH2CH2CI has utility as an intermediate in the preparation of fluroinated olefins of the invention which may be used to prepare hydrofluorocarbons. See Example 3 below.

Example 3

Vapor phase fluorination of CFιCCl?CH CH'?CI to produce

(a) Catalyst Pretreatment. While maintaining a nitrogen flow of 350 mlJmin through a 1 inch pipe reactor, palletized chrome oxide (Cr2θ3), (available from Mallinckrodt Specialty Chemicals Co., St. Louis, MO) was heated to 350°C at a rate of 50 C/h, maintained at 350°C for 8 h, then cooled to 200°C at a rate of 40 C/h. Liquid hydrogen fluoride was then metered in at a rate to keep the temperature below 250°C (about 0.8 cc min). After the exotherm had moved through the catalyst bed, the temperature was again increased to 350°C at a rate of 50 C/h, and held at 350°C for 2 h. Finally, the temperature was decreased to 250°C at a rate of 50 C/h.

(b^ Fluorination Reaction. The pretreated catalyst (150 cc) was heated to 250°C in the reactor while passing HF into the reactor at 1.4 mUmin at an operating pressure of 50 psig. The organic, CF3CCI2CH2CH2CI, was then fed at 0.7 g/min (contact time 10 sec). Gas chromatographic analysis of the reactor effluent indicated an 83 % conversion of starting material. The products, which were collected in a -78°C cold trap and identified by GC-MS, included CF ₃ CF2CH=CH ₂ (23.4 %), C4H3CIF4 isomers (5.5 %),

CF ₃ CF ₂ CH2CH ₂ CI (4.4 %), CF ₃ CCl2CH ₂ CH ₂ F (2.1 %), and C4H3CI2F3 isomers (62.9 %). The desired olefin, CF3F2CH=CH2 (bp 3-6°C) was readily recovered in high purity from the crude product by bulb-to-bulb distillation. The C4H3CI2F3 isomers were later separated via distillation using a three-foot packed column and identified as follows: fraction boiling at 95 - 101°C consisted of 10% CF3CCI2CH2CH2F and CF3CCI=CHCH2CI (86 and 4 % respectively); fraction boiling at 101°C consisted of CF3CCI2CH2CH2F (3%) and a mixture of cis- and trans- CF ₃ CCI=CHCH ₂ CI (92 and 5%). ^H NMR for CF ₃ CCl2CH ₂ CH ₂ F: δ 2.74 (dt, CH2CH2F, JH-F= 18.6Hz, JH-H = 6.3 Hz) and 4.83 (dt, CH2CH2F, JH-F = 46.2 Hz, JH-H = 6.3 Hz); ⁹ F NMR: -80.7 and -222.4 ppm. ¹ H NMR for CF ₃ CCI=CHCH ₂ CI: δ 6.61 (=CH, JH-H = 7.2 Hz, JH-F = 1.0 Hz) and 4.24 (CH2CI, JH-H = 7.2 Hz, JH-F = .5 Hz); ¹⁹ F NMR: -70.6 ppm. Cis- and trans- CF3CC CHCH2CI are useful as starting materials for the manufacture of hydrofluorocarbons which may application as solvents among other things.

(c) Recycle of underfluorinated (chlorinated by-products) materials. The by-products recovered above, specifically a mixture containing 7.5 %

CF3CCI2CH2CH2F and 92.3 % cis- and trans-CF ₃ CCI=CHCH2CI were placed into the reactor and then passed over 150 cc of the catalyst at 50 psig and a temperature of 225°C. HF feed rate was 1.4 cc/min, while the organic feed rate was 0.7 g/min corresponding to a contact time of about 10 sec. Gas chromatographic analysis of the reactor effluent indicated that it was comprised of 79 % CF3CF2CH=CH2. This indicated to us that

CF3CCI=CHCH2CI must be an intermediate in the vapor phase fluorination of CF3CCI2CH2CH2CI to CF ₃ CF2CH=CH2. Were it otherwise, the yield of CF3CF2CH=CH2 would have been much lower, reflecting the fluorination of only 7.5 % CF3CCI2CH2CH2F.

Examples 4 - 6

Vaoor phase fluorination of CF^CChCHoCH^CI to produce The experiment reported in Example 3 was repeated using the temperatures, pressures and contact times reported in Table I

below.

T A B L E I

4 5 6

Pressure (psig) 100 200 200

Temperature (C) 200 225 250

Contact time (s) 18 32 30

Conversion (%) 60 73 79

Selectivity (%) for

CF3CF2CH2CH2F 1 1 1

CF ₃ CF ₂ CH=CH2 22.1 18.1 23.4

CF ₃ CCI=CHCH ₂ CI 74.2 78.1 72.5

Other 2.7 2.8 3.1

These Examples show that there is a range of operating conditions that give useful quantities of a desired olefin.

Example 7

A stirred PTFE reactor, connected to a CaS04 drying tube, a caustic scrubber and a -78 °C cold trap, was charged with 3.2 g SbC and 55.0 g HF at 0°C. Over a period of 4.75 h, 29.0 g CF3CF2CH=CH2 was bubbled into the HF solution. After stirring for an additional hour at 0 °C, the dark red reaction mixture was poured cautiously into ice-cold 5 % aqueous KOH. The lower light brown organic phase (18.2 g) was analyzed using gas chromotography and found to contain 70.0 % CF3CF2CH2CH2F, 14.3 % CF3CF2CH2CHCI, and 15.7 % of higher boiling materials (including 8-carbon compounds). Distillation of a larger sample of crude CF3CF2CH2CH2F provided pure material having the following properties: bp 44-45°C, ¹ H NMR: δ 4.69 (dt, J = 46.4 and 5.6 Hz, CH2F) and 2.45 (m, CF2CH2); ¹⁹ F NMR: -87.1 (3 F), -118.6 (2 F, dt, J = 17.8 and 6.4 Hz), and -223.1 (1 F) ppm.

The 8-carbon compounds produced as by-products in this reaction

were identified by GC-MS as primarily isomeric olefins (2:1 ratio) of the molecular formula C8H6F10. The major isomer was identified by NMR analysis as CH2=C(CF2CF3)CH(CH3)(CF2CF3), while the minor isomer was CF ₃ CF2CH2CH=C(CH3)(CF2CF ₃ ). ¹ H NMR for the major isomer: δ 1.3 (d, CH3, 3JH-H = 7 Hz), 3.0 (m, -CH(CH3), 5.8 (dt, =CHH, J = 16 and 11 Hz), and 6.38 (dd, =CHH, J = 16 and 9 Hz); ¹⁹ F NMR: -83.7 (s, 3 F), - 87.1 (s, 3 F), -117.8 (d, 1 F), -118.0 (d, 1 F, J = 11 Hz), -121.0 (dd, 1 F, J = 271 and 11 Hz), and -124.6 (dd, 1 F, J = 271 and 18 Hz) ppm. ¹ H NMR for the minor isomer: δ 1.85 (s, 3 H), 3.0 (m, 2 H), and 6.15 (t, 1 H, J = 7 Hz); ¹⁹ F NMR: -85.5 (s, 3 F), -86.9 (s, 3 F), -188.2 (t, 2 F, J = 16 Hz), and -119.0 (s, 2 F) ppm.

Comparative Example 1

Fluorination of CF2CCI7CH2CH CI with HF/SbC . A monel autoclave was charged with 5.6 g SbCIs, 29.8 HF, and 54.2 g CF3CCI2CH2CH2CI. The contents were stirred and heated to 175°C for 14 h. The contents were vented into a caustic scrubber, followed by a -78°C cold trap. Product was recovered from the cold trap and the scrubber and analyzed using gas chromatography. Product recovered from the scrubber was identified as 40.8 g of starting material (98 % purity). The 2.2 g of product from the cold trap also identified as primarily starting material.

Comparative Example 2

Fluorination of CF-aCCbC^C^CI with HF/SbCk at higher temperature. The experiment outlined in Comparative Example 1 was repeated using the following materials and reaction conditions: 9.7 g SbCIs, 36.2 g HF, 32.3 g CF3CCI2CH2CH2CI were mixed, stirred and heated at 225°C for 14 h. Results similar to those reported in Comparative Example 1 were obtained; the scrubber contained 97 % starting material, while the cold trap contained a small amount of CF3CCl2CH=CH2 and a C4H4F4CI2 isomer. Thus, unlike CCI3CH2CH2CI which fluorinated readily to CF3CH2CH2CI with HF and antimony pentachloride at modest temperature (85°C) (U.S. Patent 4,078,007), the CCI2 group in CF3CCI2CH2CH2CI was resistant to fluorination even at elevated temperature (>175°C).

Comparative Example 3

A monel autoclave was charged with 6.5 g SbFs, 30 g HF, and 43.8 g CF3CF2CH=CH2- The mixture was heated to 105°C for 12 h. Venting the reaction mixture into a caustic scrubber, followed by cold traps, gave 33 g of product mixture, while the autoclave residue consisted of black liquid and solid. Gas chromatographic analysis of the 33 g of organic product indicated that it contained 54 % CF3CF3CH2CH2F, 33 % of a CβHeF-io isomer, and 5 % starting material.

Comparative Example 4

The experiment outlined in Comparative Example 3 was repeated using the following materials and reaction conditions: 3.9 g SnCl 20 g HF, and 43.8 g CF3CF2CH=CH2 were mixed together and heated to 98-106°C for 5 h to give 40 g of liquid product which gas chromatographic analysis indicated consisted of 94 % starting material.

Comparative Example 5

The experiment outlined in Comparative Example 3 was repeated using the following materials and reaction conditions: 8.5 g TaFs, 40.3 g HF, and 47.4 g CF3CF2CH=CH2 were mixed together and heated to 108°C for 17.5 h to give 44.3g of product which gas chromatographic analysis indicated consisted of 29 % starting material, 1 % CF3CF2CH2CH2F, 20 % CβHβF-io, and 46 % polymeric material.

These comparative examples show that use of Lewis acid catalysts and elevated temperatures (the teachings of Henne et al., discussed above) result in either little reaction or unacceptably large quantities of byproducts, such as higher boiling materials.

Comparative Examples 6 - 8

other than SbCk. The experiment outlined in Example 7 above was repeated using each of the following Lewis acid catalysts: TiCl4, SnCl4, and BF3. In each case, none of the desired CF3CF2CH2CH2F product was obtained and virtually no reaction occurred.