Method for the Recycling or Disposal of Halocarbons

Abstract

The present invention relates to a method for recycling and/or disposal of halocarbons, particularly fluorinated alkanes, such as trifluoromethane, by reacting said halocarbons with sulfur trioxide, particularly to form halide sulfonic acids and sulfur dioxide.

Claims

1. A method for conversion of halocarbons, comprising the steps of reacting a halocarbon with SO.sub.3.

2. The method according to claim 1, wherein the SO.sub.3 is present as oleum.

3. The method according to claim 1, characterized in that the halocarbon is reacted with sulfur trioxide to form the corresponding halide sulfonic acid.

4. The method according to claim 1, characterized in that the halocarbon is a hydrocarbon in which at least one H-atom is replaced by a halogen, said hydrocarbon being selected from an alkane, an alkene, or an alkyne, wherein said hydrocarbon can be linear, branched or cyclic, substituted or un-substituted.

5. The method according to claim 1, characterized in that the molecular ratio between sulfur trioxide and halocarbon is in the range of from 1 to 100.

6. The method according to claim 1, characterized in that the halocarbon is reacted with sulfur trioxide at a temperature of 0 to 200° C.

7. The method according to claim 1, characterized in that the halocarbon is reacted with sulfur trioxide at a pressure of 1 to 200 bar.

8. The method according to claim 1, characterized in that the halocarbon is a fluorinated, brominated or chlorinated derivative of an alkane.

9. The method according to claim 1, characterized in that the halocarbon comprises a single or multiple halogen atoms, wherein one or more of the carbon atom of the halocarbon are bonded to one or more halogen atoms.

10. The method according to claim 1, characterized in that the halocarbon is a halogenated derivative of a branched or unbranched alkane with a carbon number in the range of from 1 to 20, especially with a carbon number in the range of from 1 to 10.

11. The method according to claim 2, wherein a peroxide compound is added to the reaction mixture comprising halocarbon and oleum.

12. The method according to claim 11, wherein the peroxide is added stoichiometrically if the halocarbon comprises more than 1 C-atom, and the peroxide is added sub-stoichiometrically if the halocarbon comprises 1 C-atom.

13. The method according to claim 1, wherein sulfated intermediates occur during the reaction.

14. The method according to claim 13, wherein the sulfated intermediate is separated from the reaction mixture.

15. The method of claim 1, further comprising recycling or disposing of a reaction product of the conversion of halocarbons.

16. The method of claim 15, characterized in that the halocarbon is a fluoroalkane.

17. The method according to claim 6, characterized in that the halocarbon is reacted with sulfur trioxide at a pressure of 1 to 200 bar.

18. The method according to claim 2, characterized in that the halocarbon is reacted with sulfur trioxide to form the corresponding halide sulfonic acid.

19. The method according to claim 6, characterized in that the halocarbon is reacted with sulfur trioxide at a temperature of 80° C. to 125° C.

20. The method according to claim 1, wherein the halocarbon is a CF.sub.3H.

Description

EXAMPLES

Example 1: Procedure for the Decomposition of Fluoroform to Fluorosulfuric Acid

[0058]
HCF.sub.3+3 SO.sub.3+H.sub.2SO.sub.4.fwdarw.3 FSO.sub.3H+CO.sub.2+SO.sub.2

[0059] In a 4 L stainless steel high-pressure reactor containing 1.789 kg of 36% fuming sulfuric acid was added 285 g fluoroform (4.07 moles). The reactor was sealed and heated to 100° C. and the stirrer speed was set to 350 rpm. After 24 h at constant stirring, the excess pressure is released to a set of scrubbers filled with sulfuric acid and the excess fluoroform, if it is any, was stored in a stainless steel cylinder avoiding the release to the atmosphere. The pressure inside the reactor remains constant at 30.7 bar indicating the existence of dissolved CF.sub.3H in the liquid phase and gaseous CF.sub.3H in the headspace. A liquid sample is transferred to a J-Young NMR tube and .sup.19F NMR was measured against an internal standard showing 20% yield of fluorosulfuric acid (based on the initial moles of fluoroform).

Example 2: Procedure for the Decomposition of Fluoroform to Fluorosulfuric Acid

[0060] a) In a 400 mL stainless steel high-pressure reactor containing 288.2 g of 34% fuming sulfuric acid was added 19 g fluoroform (0.27 mol) increasing the pressure of the reactor to 17.3 bar. The reactor was sealed and heated to 80° C. and the stirrer speed was set to 400 rpm. The initiator was prepared dissolving 2.65 g K.sub.2S.sub.2O.sub.8 (9.8 mmol) in 12 mL H.sub.2SO.sub.4 (98%), this mixture was added into the reactor using a HPLC pump. After 4 days at constant stirring, the excess pressure was released to a set of scrubbers filled with sulfuric acid and the excess fluoroform was stored in a stainless-steel cylinder to avoid direct release to the atmosphere. A liquid sample was transferred to a J-Young NMR tube and .sup.19F NMR was measured against an internal standard showing 57% yield of fluorosulfuric acid (based on the initial moles of fluoroform).

[0061] b) Preparation without Additional Oxidant OLEUM65:

CHF.sub.3+3SO.sub.3+H.sub.2SO.sub.4.fwdarw.3FSO.sub.3H+CO.sub.2+SO.sub.2

[0062] A small stainless steel reactor (450 mL, Parr Instruments) equipped with a glass liner was charged with oleum 65 (292.5 g, 2.37 mol SO.sub.3) at 40° C. Under vigorous steering, the sealed vessel was heated to 100° C. and reached a pressure of 4.2 bar. Next the reactor was pressurized with CHF.sub.3 to reach an overall pressure of 15.3 bar (94 mmol CHF.sub.3). The reaction mixture was stirred (900 rpm) for additional 22 h. After that, the reactor was cooled down to 40° C. and all volatiles were released to scrubbers filled with sulfuric acid. The liquid reaction mixture was recovered and stored in 100 mL glass SCHOTT bottles.

[0063] A small sample (ca. 0.7 mL) was transferred to an NMR tube with Teflon cap and subjected to an analysis via .sup.19F{.sup.1H} NMR spectroscopy The yield of FSO.sub.3H (28.2 g, 282 mmol) was determined via comparison of the relative peak integral to an internal standard (C.sub.6F.sub.6) revealing the quantitative conversion of CHF.sub.3 into FSO.sub.3H.

Example 3: Procedure for the Decomposition of Difluoromethane (CH.SUB.2.F.SUB.2.)

[0064] ##STR00002##

[0065] A small stainless-steel reactor (450 mL, Parr Instruments) equipped with a glass liner was pressurized with CH.sub.2F.sub.2 at 60° C. to reach an overall pressure of 15.1 bar (0.243 mmol CH.sub.2F.sub.2); Reaction 1. Subsequently, oleum 35 (307.2 g, equates 1.23 mol SO.sub.3) was pumped into the reactor. The temperature was kept at 50° C. and a pressure of 19.2 bar was observed. Upon stirring (900 rpm) the pressure drops to 11.5 bar. Under vigorous steering, the sealed vessel was heated to 60° C. After 30 h the pressure dropped to atmospheric pressure. A small sample for .sup.19F NMR spectral analysis was taken from the reactor before it was pressurized for a second run with 12.8 bar CH.sub.2F.sub.2 (0.20 mol) at 60° C. After 36 h the pressure in the reactor reached 1.5 bar; Reaction 2.

[0066] The yield of FSO.sub.3H in Reaction 1 was (45.1 g, 0.451 mol, Yield with respect to CHF.sub.3 93%) determined comparing the relative peak integral to an internal standard (28.8 mg C.sub.6F.sub.6). .sup.19F{.sup.1H} (40.89 MHz) NMR s 45.7 (FSO.sub.3H); s 161.5 ppm (C.sub.6F.sub.6) ppm.

[0067] The reactor was cooled down to 40° C. and all volatiles were released to scrubbers filled with sulfuric acid. The liquid reaction mixture was recovered and stored in 100 mL glass SCHOTT bottles. A small sample (ca. 0.7 mL) was transferred to an NMR tube with Teflon cap and subjected to an analysis via .sup.19F{.sup.1H} NMR spectroscopy revealing the conversion of CH.sub.2F.sub.2 into FSO.sub.3H and, the organic product methylenedisulfate (MDS, CH.sub.2(SO.sub.4H).sub.2).

[0068] The yield of FSO.sub.3H in Reaction 2 (second CHF.sub.3 charge) was (28.4 g, 0.284 mol, yield with respect to CHF.sub.3 70%) determined via comparison of the relative peak integral to an internal standard (C.sub.6F.sub.6).

Example 4: Procedure for the Efficient Decomposition of Dichloromethane (CH.SUB.2.Cl.SUB.2.) without Usage of a Catalyst

[0069] ##STR00003##

[0070] A Fisher Porter pressure reaction vessel equipped with pressure gauge and magnetic stirbar was charged with Oleum 34 (27,277 g). Dichloromethane (DCM, 3 mL) was added slowly directly into the oleum without cooling. Caution, the reaction is violent, when DCM is not carefully added dropwise. The reaction mixture forms two phases. The Fisher Porter vessel was closed and the mixture was heated to 90° C. under vigorous stirring. After 3 h the stirring was stopped and the reaction mixture was allowed to cool down to ambient temperature. At this point, no phase separation was present.

[0071] Subsequently, a small sample (ca. 0.7 mL) was transferred to an NMR tube with Teflon cap and subjected to an analysis via .sup.1H and .sup.13C{.sup.1H}, and .sup.13C.sup.1H HSQC NMR spectroscopy revealing a full conversion of CH.sub.2C.sub.2 (s, 5.36 ppm in NMR spectrum) and formation of the major product methylene bis(chlorosulfate) MBCS (.sup.1H NMR br s, 6.07 ppm, .sup.13C{.sup.1H}, NMR s 91.77 ppm)

[0072] When an excess of CH.sub.2Cl.sub.2 is present, chloromethyl chlorosulfate (CMCS) is subsequently formed.

[0073] NMR chemical shifts (ppm) reported by Bethell et al. Org. Biomol. Chem. 2004, 2, 1554-62. MBCS: .sup.13C: 92.18 .sup.1H: 6.14 in CDCl.sub.3 CMCS: .sup.13C: 77.32 .sup.1H: 5.96 in CDCl.sub.3

[0074] NMR Chemical Shifts (ppm) Found:

[0075] MBCS: .sup.13C: 91.77 .sup.1H: 6.07 in H.sub.2SO.sub.4 CMCS: .sup.13C: 76.00 .sup.1H: 5.86 in H.sub.2SO.sub.4

[0076] Isolation:

[0077] MBCS and CMCS can be extracted from the reaction mixture: The reaction mixture was treated carefully with water to quench residual SO.sub.3. Subsequently the mixture was extracted three times with dichloromethane (ca 3 mL each extraction). The organic layer was filtered through a PTFE syringe filter and all volatiles where evaporated at atmospheric pressure to obtain the pure products.

Example 5: Preparation of Fluoro Sulfonic Acid (FSO.SUB.3.H) Via the Thermal Decomposition of 1,1,1,2 Tetrafluorethane (R134) in Fuming Sulfuric Acid

[0078]
R134+Oleum34+excess K.sub.2S.sub.2O.sub.8.fwdarw.3FSO.sub.3H+CO.sub.2 (90° C., 5 bar)

[0079] A high pressure NMR tube (NORELL, EXTREME Series Level 3, thin wall, Kalrez O-rings) was charged with 0.5 mL Oleum34 and subsequently pressurized with 5 bar 1,1,1,2 tetrafluorethane (R134)). The reaction was followed by .sup.1H and .sup.19F NMR spectroscopy.

[0080] Starting Material:

[0081] .sup.19F (40.89 MHz) NMR of R134 in Oleum34: −75.5 (3F, dt, J=15.9; 8.1 Hz, CF.sub.3); −236.4 (1F, tq J=45.5; 15.6, ppm, CH.sub.2F) ppm.

[0082] .sup.1H NMR (44 MHz) of R134 in Oleum34: 4.77 (2H, dq, J=45.1; 8.1 Hz, CH.sub.2F)

[0083] The formation of FSO.sub.3H was not detected after 16 h at 85° C. without utilization of an oxidant. Upon addition of an excess of K.sub.2S.sub.2O.sub.8 the formation of FSO.sub.3H can be detected and followed in the .sup.19F NMR spectrum within 2 h. After 21 h at 85° C., 1,1,1,2 tetrafluorethane (R134) reacted quantitatively and the formation of FSO.sub.3H in 85% yield was observed. The .sup.1H NMR spectra indicate no formation of a major non-fluorinated byproduct, (e.g. such as methylene di(sulfate) or similar).

Example 6: Preparation of Fluoro Sulfonic Acid (FSO.SUB.3.H) Via the Thermal Decomposition of 2,3,3,3,-Tetrafluorpropylen (R1234yf) in Fuming Sulfuric Acid

[0084]
R1234yf+Oleum34+excess K.sub.2S.sub.2O.sub.8.fwdarw.3FSO.sub.3H+CO.sub.2 (90° C., 5 bar)

[0085] A high pressure NMR tube (NORELL, EXTREME Series Level 3, thin wall, Kalrez O-rings) was charged with 0.5 mL Oleum34 and subsequently pressurized with 5 bar 2,3,3,3,-tetrafluorpropylen (R1234yf). The reaction was followed by .sup.1H and .sup.19F NMR spectroscopy. .sup.19F{.sup.1H} (40.89 MHz) NMR of R1234yf in Oleum34: br s overlay with intrinsic residual peak of spectrometer at ca −74 (br) ppm.

[0086] The formation of FSO.sub.3H was detected already after 15 min at ambient temperature without the addition of an oxidant. After 1 h at 90° C. the .sup.19F NMR spectrum includes besides the singlet associated with FSO.sub.3H at 44 ppm only three additional singlets (−70.0; −75.2; −76.4 ppm). Remarkably, the absence of any J coupling indicates only C—F moieties without any coupling H or F neighboring atoms.

[0087] Pressure release did not result in the depletion of the singlet resonances associated with the initially formed byproducts, therefore we anticipate that the intermediates are not gaseous. To the mixture, an excess of K.sub.2S.sub.2O.sub.8 was added (200 mg). Upon addition of K.sub.2S.sub.2O.sub.8 vigorous gas formation was observed. The reaction mixture was further heated at 90° C. for 6 h in the closed NMR tube. An increase of the integral of the area peak associated with FSO.sub.3H was observed. However residual peaks remain in the area between −65 and −80 ppm.

[0088] Conversion: 100% of R1234yf

[0089] Yield: FSO.sub.3H 60% with respect to all F-containing products formed

Example 7 Preparation of Fluoro Sulfonic Acid (FSO.SUB.3.H) Via the Thermal Decomposition of Perfluoro Octanoic Acid in Fuming Sulfuric Acid

[0090]
PFOA+Oleum34+xsK.sub.2S.sub.2O.sub.8.fwdarw.3FSO.sub.3H+CO.sub.2 (80° C.))

[0091] A J Young NMR tube (NORELL) was charged with 0.5 mL Oleum34 and 15 mg perfluoro octanoic acid (PFOA) The reaction was followed by .sup.19F NMR spectroscopy. No reaction was observed in the absence of an oxidizer within 3 h at 80° C. Upon addition of an excess amount of K.sub.2S.sub.2O.sub.8 and heating the sample at 80° C. for 30 min formation of FSO.sub.3H was observed by means of .sup.19F NMR spectroscopy. Allowing the mixture to react overnight (16 h) gave rise to a significant degradation of PFOA and concomitant formation of FSO.sub.3H.

[0092] Conversion: 70% of PFOA