Catalytic isomerization of Z-1,1,1,4,4,4-hexafluoro-2-butene to E-1,1,1,4,4,4-hexafluoro-2-butene

Abstract

A process is disclosed for (i) producing E-1,1,1,4,4,4-hexafluoro-2-butene (E-HFO-1336mzz) from Z-1,1,1,4,4,4-hexafluoro-2-butene (Z-HFO-1336mzz), comprising the steps of (a) providing a starting material comprising Z-1,1,1,4,4,4-hexafluoro-2-butene, (b) contacting the starting material with a suitable catalyst in a reaction zone to produce E-HFO-1336mzz; and optionally, (c) recovering the E-HFO-1336mzz. The process may be performed in the gas phase or in the liquid phase and as a batch process or as a continuous process.

Claims

1. A process for isomerizing Z-1,1,1,4,4,4-hexafluoro-2-butene to E-1,1,1,4,4,4-hexafluoro-2-butene comprising: (a) providing a starting material comprising Z-1,1,1,4,4,4-hexafluoro-2-butene; (b) contacting the starting material with a suitable catalyst in a reaction zone to produce E-HFO-1336mzz; and optionally, (c) recovering the E-HFO-1336mzz, wherein, when the contacting step is performed in the gas phase, the catalyst comprises chromium and less than 40% by weight alumina; wherein when the contacting step is performed in the liquid phase, the catalyst comprises a metal halide wherein the metal halide is aluminum halide, antimony halide, tin halide, tantalum halide, titanium halide, niobium halide, molybdenum halide, iron halide, fluorinated chrome halide, or combinations thereof.

2. The process of claim 1 wherein the contacting step is performed in the gas phase.

3. The process of claim 1 wherein the contacting step is performed in the liquid phase.

4. The process of claim 1 further comprising recovering the E-HFO-1336mzz.

5. The process of claim 1 wherein a suitable catalyst comprises chromium oxyfluoride.

6. The process of claim 1 wherein a suitable catalyst contains SbCl.sub.5, SbCl.sub.3, SbF.sub.5, SnCl.sub.4, TaCl.sub.5, TiCl.sub.4, NbCl.sub.5, MoCl.sub.6, FeCl.sub.3, a fluorinated species of SbCl.sub.5, a fluorinated species of SbCl.sub.3, a fluorinated species of SnCl.sub.4, a fluorinated species of TaCl.sub.5, a fluorinated species of TiCl.sub.4, a fluorinated species of NbCl.sub.5, a fluorinated species of MoCl.sub.6, a fluorinated species of FeCl.sub.3, or combinations thereof.

7. The process of claim 6 wherein a suitable catalyst contains MCl.sub.5-nF.sub.n, wherein M=Sb or Ta and n=0-5.

8. The process of claim 7 wherein the catalyst is antimony pentafluoride.

9. The process of claim 7 wherein the catalyst is tantalum pentafluoride.

10. The process of claim 6 wherein a suitable catalyst contains AlZ.sub.3, wherein Z is one or more of Br, F or Cl, provided that Z cannot be entirely F.

11. The process of claim 10 wherein AlZ.sub.3 has the formula AlCl.sub.xF.sub.y, where the total number of atoms of halide, x plus y equals 3, where x ranges from about 0.05 to 2.95 and y ranges from about 2.95 to 0.05.

12. The process of claim 2 wherein the temperature in the reaction zone is in the range from about 100 C. to about 500 C.

13. The process of claim 12 wherein the temperature in the reaction zone is in the range from about 150 C. to about 400 C.

14. The process of claim 13 wherein the temperature in the reaction zone is in the range from about 250 C. to about 300 C.

15. The process of claim 3 wherein the temperature in the reaction zone is in the range of 20 C. to about 150 C.

16. The process of claim 15 wherein the temperature in the reaction zone is in the range of from about 50 C. to about 150 C.

17. The process of claim 16 wherein the temperature in the reaction zone is in the range of from about from about 100 C. to about 130 C.

18. The process of claim 1 wherein the process is a batch process.

19. The process of claim 1 wherein the process is a continuous process.

20. The process of claim 2 wherein the process is a batch process.

21. The process of claim 2 wherein the process is a continuous process.

22. The process of claim 3 wherein the process is a batch process.

23. The process of claim 3 wherein the process is a continuous process.

24. The process of claim 1 wherein the starting material comprises Z-1336mzz and E-1336mmzz.

25. The process of claim 1 wherein the yield of E-1336mzz is at least 90 mole %.

26. The process of claim 1 wherein the yield of E-1336mzz is at least 95 mole %.

27. The process of claim 1 wherein the yield of E-1336mzz is at least 99 mole %.

28. The process of claim 1 wherein there is unreacted Z-1336mzz in the product, and wherein such unreacted Z-1336mzz is separated from the product and recycled to the reaction zone.

Description

EXAMPLES

(1) SbF.sub.5, SbCl.sub.5, TaCl.sub.5 are available from Sigma Aldrich, St. Louis, Mo. Hydrogen fluoride was purchased from SynQuest Labs, Inc., Alachua, Fla.

Examples 1-4. Liquid Phase Isomerization of Z-1336mzz to E-1336mzz Using SbCl5 or TaCl5 Catalyst

(2) Catalyst, SbCl.sub.5 (5 g, 0.016 mol) or TaCl.sub.5 (6.15 g, 0.016 mol) was added into a 210 mL Hastelloy C reactor, followed by HF addition (20 g, 1 mol). The reaction mixture was heated to 100 C. for 1 hour and cooled to 0 C. Z-1336mzz (30 g, 0.18 mol) was added and the vessel and the reaction as heated back to 100 C. for 20 hours. 50 g ice water was added to quench the reaction. The product was analyzed by GC.

(3) Results are summarized in Table 1.

(4) TABLE-US-00001 TABLE 1 Liquid Phase Isomerization Results Example # 1 2 3 4 Z-1336mzz 30 g 30 g 30 g 30 g (0.18 mol) (0.18 mol) (0.18 mol) (0.18 mol) HF 20 g 20 g 20 g 20 g (1 mol) (1 mol) (1 mol) (1 mol) SbCl.sub.5 5 g (0.016 mol) TaCl.sub.5 6.15 6.15 6.15 (0.016 mol) (0.016 mol) (0.016 mol) Temperature 100 130 130 110 ( C.) Time (hrs) 20 20 10 20 Conversion (%) 44.6 96.5 72.5 75.3 Selectivity to 98.3 99.5 99.7 99.8 E-1336mzz (%) Yield* of E- 98.3 98.5 99.7 99.8 1336mzz (%) *Based on recovered Z-1336mzz.

Example 5. Liquid Phase Isomerization of Z-1336mzz to E-1336mzz Using SbF5 Catalyst

(5) Antimony pentafluoride (SbF.sub.5, 1 g) was placed in 50 mL round bottomed flask inside of a dry box. The reaction vessel was transferred into a fume hood and was equipped with thermocouple, dry ice condenser, addition funnel and magnetic stir bar. 20 g of cis-HFO-1336mzz (containing 0.3 mol % of the trans isomer) was added to reaction vessel at 0 C. over a 15 minute period, under nitrogen blanket. The reaction mixture was agitated at ambient temperature for 3 days (reaction vessel was kept at 78 C. overnight and the reaction was resumed next morning). The conversion of cis-HFO-1336mzz was monitored by GC and .sup.19F NMR. After 3 days (28 hours total at ambient temperature) the ratio of cis/trans was found to be 0.4:99.6.

Example 6. Liquid Phase Isomerization of Z-1336mzz to E-1336mzz Using Aluminum Chlorofluoride Catalyst

(6) Aluminum chlorofluoride (AlCl.sub.xF.sub.y, ACF, 0.4 g, prepared in accordance with U.S. Pat. No. 5,162,594) was placed in a 50 mL round bottomed flask inside of a dry box. The reaction vessel was transferred into a fume hood and was equipped with thermocouple, dry ice condenser, addition funnel and magnetic stir bar. 20 g of cold cis-HFO-1336mzz (containing 0.1 mol % of the trans isomer) was added to a reaction vessel at 20 C. over a 15 minute period, under nitrogen blanket.

(7) The temperature of the reaction mixture went from 10 C. to 24 C. during the addition step. The reaction mixture was agitated at ambient temperature for 2 hours. The conversion of cis-HFO-1336mzz into the trans isomer was monitored by .sup.19F NMR. According NMR data the ratio of cis/trans isomers changed from 99.9:01 (starting material) to 0.6:99.4 in the crude product after 2 hours at ambient temperature.

Examples 7-9. Gas Phase Isomerization of Z-1336mzz to E-1336mzz

(8) Catalyst Preparation and Activation

(9) Into an Inconel (0.5 inch OD) tube was added 6 cc of chromium oxide, formed by pressing hydrated chromic oxide powder at 30,000 lb. The resulting mass was crushed and sieved to 12/20 mesh.

(10) The chromium oxide was converted to chromium oxyfluoride and activated as follows. The chromium oxide was heated at 300 C. under 30 cc/min of nitrogen flow for 200 minutes. Then nitrogen flow was increased to 60 cc/min and HF was introduced at 20 cc/min for 60 minutes. Then the temperature was increased to 325 C. for 300 minutes. Then the nitrogen and HF flow were each set to 30 cc/min for 30 minutes. Then nitrogen flow was lowered to 12 cc/min and HF flow was increased to 48 cc/min for 60 minutes. The nitrogen was then turned off and HF was allowed to flow at 48 cc/min. for an additional 30 minutes. The temperature of the reactor was then decreased to 250 C. for 30 minutes. After activation, the reactor was purged with nitrogen.

(11) Run Conditions and Results

(12) A stream of Z-1,1,1,4,4,4-hexafluoro-2-butene (Z-HFO-1336mzz) preheated at 50 C. was fed into the tube reactor. Part of the reactor effluent was passed through a series of valves and analyzed by GCMS.

(13) In Examples 7 and 8, the catalyst was as described above. In Example 7, the gas flow rate of Z-1336mzz fed to the reactor was 9.51 standard cubic centimeters per minute (sccm). In Example 8, the gas flow rate of Z-1336mzz fed to the reactor was 4.75 sccm.

(14) In Example 9 (Comparative), no catalyst was used. In Example 9, the gas flow rate of Z-1336mzz fed to the reactor was 4.75 sccm.

(15) Reaction temperatures, feed rates and results are listed in Tables 2-4 below.

(16) TABLE-US-00002 TABLE 2 Results - Example 7 Mole Percent Run No. Temp, C. Z-1336mzz E-1336mzz Others 1 150 63.32 36.65 0.02 2 150 67.65 32.32 0.02 3 150 68.39 31.59 0.02 4 250 0.81 99.15 0.04 5 250 0.79 99.18 0.04 6 250 0.78 99.20 0.02 7 300 1.13 98.83 0.04 8 300 1.15 98.81 0.04 9 300 1.13 98.83 0.03

(17) TABLE-US-00003 TABLE 3 Results - Example 8 Mole Percent Run No. Temp, C. Z-1336mzz E-1336mzz Others 1 100 99.09 0.56 0.26 2 100 99.50 0.48 0.01 3 100 99.52 0.47 0.01 4 150 91.48 8.51 0.01 5 150 87.98 12.00 0.02 6 150 87.69 12.30 0.02 7 200 16.22 83.77 0.02 8 200 12.21 87.78 0.02 9 200 15.50 84.48 0.02

(18) TABLE-US-00004 TABLE 4 Results - Example 9 (Comparative) Mole Percent Run No. Temp, C. Z-1336mzz E-1336mzz Others 1 150 99.82 0.17 0.01 2 150 99.89 0.09 0.01 3 200 99.92 0.06 0.01 4 200 99.94 0.05 0.01 5 251 99.94 0.05 0.02 6 250 99.93 0.05 0.01 7 300 99.92 0.06 0.01 8 300 99.94 0.05 0.02 9 350 99.83 0.15 0.01