Process for the preparation of potassium trifluoromethylsulfinate

Abstract

The application provides a preparation method of potassium trifluoromethylsulfinate, and belongs to the technical field of preparation of trifluorosulfinate, and comprises the following steps: firstly, neutralizing trifluoroacetic acid and potassium hydroxide to obtain potassium trifluoroacetate; then, adding the potassium trifluoroacetate into acetonitrile as a solvent and sulfur dioxide as a sulfination reagent, and under the action of a composite catalyst, potassium trifluoromethylsulfinate is prepared through decarboxylation-sulfination to obtain a mixed solution containing the potassium trifluoromethylsulfinate; the composite catalyst is a halide salt and a phase transfer catalyst; finally, the mixed solution containing the potassium trifluoromethylsulfinate is subjected to desolventization, cooling and centrifugation to obtain the potassium trifluoromethylsulfinate; therefore, the application uses low-cost and easily-obtained trifluoroacetic acid as a raw material to prepare the potassium trifluoromethylsulfinate, thereby reducing the cost of producing the potassium trifluoromethylsulfinate, finding a new synthesis path of a downstream derivative of the trifluoroacetic acid, and extending the product value chain.

Description

Technical Field

[0001] This invention relates to the field of trifluorosulfinate preparation technology, specifically to a method for preparing potassium trifluoromethylsulfinate. Background Technology

[0002] Potassium trifluoromethanesulfinate (CF3SO2K), a typical trifluoromethanesulfinate, is an important organofluorine compound. Organic molecules containing trifluoromethyl (CF3) structural units have broad application prospects in pesticides, pharmaceuticals, and materials science. Introducing a trifluoromethyl group can significantly enhance the chemical and metabolic stability of drugs, improve their lipophilicity and bioavailability, and simultaneously increase their binding selectivity to target proteins. Therefore, developing efficient and economical trifluoromethylation reagents has become one of the important directions in organic synthesis methodology research.

[0003] Currently, potassium trifluoromethyl sulfinate is mainly prepared by the following method: potassium trifluoroacetate is dissolved in an aprotic polar solvent such as DMF, sulfur dioxide (SO2) is bubbled into the solution, and the reaction is carried out in a closed reactor at 140°C for 4–5 hours. The molar ratio of SO2 to potassium trifluoroacetate is approximately 21:1. However, the reaction conversion rate in this method is poor, with nearly 50% or more of the raw materials failing to react completely, and the product cannot be separated, resulting in waste of raw materials and failure to obtain the product. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing potassium trifluoromethyl sulfinate to improve the conversion rate of the reaction and to obtain the product easily.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A method for preparing potassium trifluoromethyl sulfinate includes the following steps:

[0007] S1: Trifluoroacetic acid and potassium hydroxide are neutralized to obtain potassium trifluoroacetate;

[0008] S2: Using sulfur dioxide as the sulfinating agent and acetonitrile as the solvent, potassium trifluoroacetate is added, and potassium trifluoromethyl sulfinate is obtained through decarboxylation-sulfination under the action of a composite catalyst, resulting in a mixed solution containing potassium trifluoromethyl sulfinate; the composite catalyst is a halosalt and a phase transfer catalyst to improve the yield of potassium trifluoromethyl sulfinate.

[0009] S3: Then, the mixed solution containing potassium trifluoromethyl sulfinate is desolvated, cooled, and centrifuged to obtain potassium trifluoromethyl sulfinate.

[0010] Preferably, step S2 specifically comprises:

[0011] S21: Under stirring conditions, potassium trifluoroacetate powder is added to acetonitrile to obtain a raw material solution;

[0012] S22: Add the composite catalyst to the raw material liquid to dissolve it, then draw a negative pressure and replace it with nitrogen to obtain the reaction solution;

[0013] S23: Sulfur dioxide is introduced into the reaction solution and kept at 80℃-90℃ for 2h-3h to obtain a reaction solution containing potassium trifluoromethyl sulfinate.

[0014] Preferably, the water content of the acetonitrile, sulfur dioxide, and composite catalyst is below 50 ppm.

[0015] Preferably, the reaction pressure is 0.15 MPa to 0.3 MPa.

[0016] Preferably, in step S22, the negative pressure is -0.01 MPa.

[0017] Preferably, in step S2, the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:1-3.

[0018] Preferably, the halosalt includes an initiating halosalt and a stable reactive halosalt.

[0019] Preferably, the amount of the initiating halide salt is 15-25 mol of potassium trifluoroacetate, the amount of the phase transfer catalyst is 3-5 mol of potassium trifluoroacetate, and the amount of the stabilizing halide salt is 0.5-2 mol of potassium trifluoroacetate.

[0020] Preferably, the initiating halide is one or more of potassium iodide, potassium fluoride, potassium bromide, cuprous bromide, and cuprous iodide.

[0021] Preferably, the stable reactive halide salt is one of aluminum chloride, ferric chloride, zinc chloride, and tin chloride.

[0022] Preferably, in step S1, the temperature of the neutralization reaction is below 35°C, and the reaction time is 3-8 hours.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention provides a method for preparing potassium trifluoromethyl sulfinate. First, trifluoroacetic acid and potassium hydroxide are neutralized to obtain potassium trifluoroacetate. Then, using sulfur dioxide as a sulfinating agent and acetonitrile as a solvent, potassium trifluoroacetate is added, and under the action of a composite catalyst, potassium trifluoromethyl sulfinate is obtained through decarboxylation-sulfinization, resulting in a mixed solution containing potassium trifluoromethyl sulfinate. The composite catalyst is a halide salt and a phase transfer catalyst. Finally, the mixed solution containing potassium trifluoromethyl sulfinate is subjected to solvent removal, cooling, and centrifugation to obtain potassium trifluoromethyl sulfinate. Therefore, this invention uses low-cost and readily available trifluoroacetic acid as a raw material to prepare potassium trifluoromethyl sulfinate, which reduces the cost of producing potassium trifluoromethyl sulfinate, increases the synthetic pathway for downstream derivatives of trifluoroacetic acid, and extends the product value chain.

[0025] Meanwhile, in the reaction process, the composite catalytic system composed of halosalt and phase transfer catalyst allows the introduction of halosalt to precisely initiate the free radical chain process of decarboxylation-sulfinization reaction. Its unique mechanism effectively suppresses side reaction pathways (such as over-oxidation to trifluoromethanesulfonic acid and the reaction of potassium trifluoromethylsulfinate with carbon dioxide to form potassium trifluoroacetate), reducing impurity generation at its source. Secondly, the phase transfer catalyst acts as a "molecular bridge," breaking down the mass transfer barriers between the gas (sulfur dioxide), liquid (acetonitrile solvent), and solid (potassium trifluoroacetate) phases, allowing reactants to fully contact under mild conditions, significantly improving reaction efficiency and product yield. Furthermore, the feed ratio of the highly toxic sulfur dioxide is significantly reduced compared to traditional processes (only 1-3 times the theoretical ratio), reducing both tail gas treatment pressure and safety risks. Compared to the original reaction conditions requiring high temperatures (e.g., above 140°C), the reaction temperature of this invention is significantly lower, reducing energy consumption and equipment corrosion problems caused by high temperatures.

[0026] Finally, because the composite catalyst effectively suppresses the occurrence of side reactions, the reaction system contains few types and low concentrations of impurities. This invention further optimizes acetonitrile as the reaction solvent, whose unique polar parameters give potassium trifluoromethyl sulfinate excellent solubility and dispersibility in the reaction solution. Furthermore, as the reaction concludes, the product can be efficiently separated through simple physical operations of solvent removal, cooling, and centrifugation, resulting in a potassium trifluoromethyl sulfinate product with a purity exceeding 95%. Attached Figure Description

[0027] Figure 1 This is a purity test result for potassium trifluoromethyl sulfinate in Example 1.

[0028] Figure 2 This is a graph showing the purity test of trifluoroacetic acid in Example 1. Detailed Implementation

[0029] To facilitate understanding of this application, a more comprehensive description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are also given. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of this application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] A method for preparing potassium trifluoromethyl sulfinate includes the following steps:

[0032] S1: Trifluoroacetic acid and potassium hydroxide are neutralized to obtain potassium trifluoroacetate;

[0033] S2: Using sulfur dioxide as the sulfinizing agent and acetonitrile as the solvent, potassium trifluoroacetate is added, and potassium trifluoromethyl sulfinate is obtained through decarboxylation-sulfinization under the action of a composite catalyst, resulting in a mixed solution containing potassium trifluoromethyl sulfinate; the composite catalyst is a halide salt and a phase transfer catalyst; the reaction is initiated by the halide salt while reducing side reactions (avoiding the formation of trifluoromethanesulfonic acid and potassium trifluoroacetate), and it works synergistically with the phase transfer catalyst to enable gas-phase, solid-phase, and liquid-phase reactions, thereby lowering the reaction temperature, increasing the reaction rate, and improving the product yield;

[0034] S3: Then, the mixed solution containing potassium trifluoromethyl sulfinate is desolvated, cooled, and centrifuged to obtain potassium trifluoromethyl sulfinate.

[0035] This invention uses acetonitrile as a solvent. Acetonitrile has a low boiling point, and after the reaction, it can be efficiently recovered and reused through simple distillation. The solvent loss is small, the recovery cost is low, and acetonitrile has low toxicity, making the process more green and environmentally friendly.

[0036] Furthermore, step S2 specifically includes:

[0037] S21: Under stirring conditions, potassium trifluoroacetate powder is added to acetonitrile to obtain a raw material solution;

[0038] S22: Add the composite catalyst to the raw material liquid to dissolve it, then draw a negative pressure and replace it with nitrogen to obtain the reaction solution;

[0039] S23: Sulfur dioxide is introduced into the reaction solution and kept at 80℃-90℃ for 2h-3h to obtain a reaction solution containing potassium trifluoromethyl sulfinate. Preferably, the temperature is 85℃-88℃. This works synergistically with the composite catalyst to avoid the generation of impurities.

[0040] Furthermore, the water content of the acetonitrile, sulfur dioxide, and composite catalyst is below 50 ppm to avoid the influence of moisture on the reaction.

[0041] Furthermore, the reaction pressure is 0.15 MPa - 0.3 MPa.

[0042] Furthermore, in step S22, the negative pressure is -0.01 MPa.

[0043] Furthermore, in step S2, the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:1-3.

[0044] Furthermore, the halosalt includes an initiating halosalt and a stabilizing halosalt; the initiating halosalt initiates the reaction, and the stabilizing halosalt controls the reaction equilibrium and reduces reversible reactions.

[0045] Furthermore, the amount of the initiating halide salt is 15-25 mol of potassium trifluoroacetate, the amount of the phase transfer catalyst is 3-5 mol of potassium trifluoroacetate, and the amount of the stabilizing halide salt is 0.5-2 mol of potassium trifluoroacetate.

[0046] Furthermore, the initiating halide salt is one or more of potassium iodide, potassium bromide, potassium fluoride, cuprous bromide, and cuprous iodide, used as an initiator to promote the reaction.

[0047] Furthermore, the phase transfer catalyst is a quaternary ammonium salt, which promotes the transformation of the gas-liquid-solid three-phase reaction into a homogeneous phase, thereby improving the reaction efficiency. The quaternary ammonium salt is a tetraalkylammonium salt or a long-chain alkylammonium salt.

[0048] Furthermore, the stabilizing halide salt is one of aluminum chloride, ferric chloride, zinc chloride, and tin chloride, in order to stabilize the reaction, disrupt the equilibrium, and prevent its conversion into impurities.

[0049] Furthermore, in step S1, the temperature of the neutralization reaction is below 35°C, and the reaction time is 3-8 hours.

[0050] Furthermore, step S3 specifically includes the following steps:

[0051] S31: The mixed solution containing potassium trifluoromethyl sulfinate is subjected to vacuum distillation to distill off acetonitrile and sulfur dioxide at 70°C. The gas is condensed once to recover acetonitrile and condensed again to recover sulfur dioxide, resulting in a mixed solution. Solvent and sulfur dioxide are recovered, reducing raw material consumption.

[0052] S32: Filter the mixture to remove the composite catalyst, obtaining filtrate and composite catalyst; the composite catalyst is recycled to step S2 for reuse (5-6 batches), greatly reducing the amount of catalyst used; the filtrate is subjected to a negative pressure of -0.07~-0.08 MPa, heated to below 70℃ to remove about 40-45% of acetonitrile (the removed acetonitrile is distilled and reused), then cooled to 12℃-15℃, kept at this temperature and allowed to stand for 1.5-3 hours, centrifuged and crystallized to obtain potassium trifluoromethyl sulfinate.

[0053] S33: Continue to desolvent the remaining mother liquor after centrifugation until it becomes viscous, centrifuge, dry, and obtain potassium trifluoroacetate, which is then reused in step S2.

[0054] Example 1:

[0055] S1: 1.01 mol of potassium hydroxide was slowly added dropwise to 1 mol of trifluoroacetic acid for neutralization. The reaction temperature was controlled to not exceed 35℃ throughout the process, and the addition time was 3 hours. After the addition was completed, the reaction was maintained at the same temperature for another 3 hours. After the reaction was completed, the product was dried at -0.095 MPa and 110℃ for 4-6 hours to obtain 152.5 g of potassium trifluoroacetate. The product content was ≥97%, the yield was 97.2%, and the moisture content was ≤200 ppm.

[0056] S2: Add 1000 mL of acetonitrile (moisture content ≤ 50 ppm) to a high-pressure reactor, start stirring, and slowly add 1 mol of potassium trifluoroacetate powder, stirring for 15 min. Then, add the initiating halide salt, phase transfer catalyst, and stabilizing halide salt sequentially (these three constitute a composite catalyst), and continue stirring for 30 min until completely dissolved. Evacuate the reaction system to -0.01 MPa and purge with nitrogen three times. Cool to 10℃, slowly introduce sulfur dioxide, and control the reaction pressure at 0.2 MPa. Raise the temperature to 85℃ within approximately 1 hour and maintain the reaction at 85–88℃. After maintaining the temperature for 1 hour, begin sampling to analyze the product content. The total holding time should be controlled to 2–3 hours. After the reaction is complete, a mixed solution containing potassium trifluoromethyl sulfinate is obtained.

[0057] The molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:3; the initiating halide salt is potassium fluoride, and the amount of potassium fluoride fed is 20 mol% of potassium trifluoroacetate; the phase transfer catalyst is tetrabutylammonium bromide, and the amount of tetrabutylammonium bromide fed is 4 mol% of potassium trifluoroacetate; the stabilizing halide salt is zinc chloride, and the amount of zinc chloride fed is 1 mol% of potassium trifluoroacetate.

[0058] S3: The mixed solution containing potassium trifluoromethyl sulfinate is subjected to vacuum distillation to remove acetonitrile and sulfur dioxide at 70°C. The distilled gas is condensed in a first stage to recover acetonitrile, and then condensed in a second stage to recover sulfur dioxide, leaving a mixed liquid. The recovered acetonitrile is purified to a water content of ≤50ppm and then reused in step S2; the recovered sulfur dioxide is also reused in step S2.

[0059] The above mixture is filtered to remove the composite catalyst, yielding a filtrate and the composite catalyst. The separated composite catalyst can be reused in step S2.

[0060] The filtrate was heated to below 70°C under negative pressure (-0.07 to -0.08 MPa) to remove approximately 40% to 45% of acetonitrile (the removed acetonitrile was purified and reused in step S2). It was then cooled to 12–15°C at a rate of 5°C / h, held at that temperature for 2 hours, centrifuged, crystallized, and dried to obtain 146.2 g of potassium trifluoromethyl sulfinate product, with a yield of 81.4% and a purity of 96% (see [link to product description]). Figure 1 ).

[0061] The remaining mother liquor was further desoluble until it became viscous, and then centrifuged and dried to obtain approximately 25.65 g of potassium trifluoroacetate with a purity of 97%, which could be reused in step S2.

[0062] Wherein: Potassium trifluoromethyl sulfinate yield = [(actual potassium trifluoromethyl sulfinate mass × actual potassium trifluoromethyl sulfinate purity) / theoretical potassium trifluoromethyl sulfinate mass] × 100%.

[0063] Example 2

[0064] In step S2, the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:2.5, the initiating halide is potassium iodide, and the amount of potassium iodide added is 20 mol% of potassium trifluoroacetate. The phase transfer catalyst is tetrabutylammonium bromide, and the amount of tetrabutylammonium bromide added is 3.5 mol% of potassium trifluoroacetate. The stabilizing halide is zinc chloride, and the amount of zinc chloride added is 0.5 mol% of potassium trifluoroacetate.

[0065] In step S3, 142.7 g of potassium trifluoromethyl sulfinate was obtained, with a yield of 80.4% and a purity of 97%. Approximately 26 g of potassium trifluoroacetate was also obtained, with a purity of 97%.

[0066] The other parts are the same as in Example 1.

[0067] Example 3

[0068] In step S2, the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:2, the initiating halide is potassium iodide, and the amount of potassium iodide added is 20 mol% of potassium trifluoroacetate. The phase transfer catalyst is benzyltriethylammonium chloride, and the amount of benzyltriethylammonium chloride added is 4 mol% of potassium trifluoroacetate. The stabilizing halide is aluminum chloride, and the amount of aluminum chloride added is 0.5 mol% of potassium trifluoroacetate.

[0069] In step S3, 147.2 g of potassium trifluoromethyl sulfinate was obtained, with a yield of 81.2% and a purity of 95%. Approximately 23 g of potassium trifluoroacetate was also obtained, with a purity of 97%.

[0070] The other parts are the same as in Example 1.

[0071] Example 4

[0072] In step S2, the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:1.3, the initiating halide is potassium iodide, and the amount of potassium iodide added is 20 mol% of potassium trifluoroacetate. The phase transfer catalyst is benzyltriethylammonium chloride, and the amount of benzyltriethylammonium chloride added is 3.5 mol% of potassium trifluoroacetate. The stabilizing halide is zinc chloride, and the amount of zinc chloride added is 1 mol% of potassium trifluoroacetate.

[0073] In step S3, 144.48 g of potassium trifluoromethyl sulfinate was obtained, with a yield of 80.6% and a purity of 96%. Approximately 27 g of potassium trifluoroacetate was also obtained, with a purity of 97%.

[0074] The other parts are the same as in Example 1.

[0075] Example 5

[0076] In step S2, the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:1.5, the initiating halide salt is potassium fluoride, and the amount of potassium fluoride added is 20 mol% of potassium trifluoroacetate. The phase transfer catalyst is tetrabutylammonium bromide, and the amount of tetrabutylammonium bromide added is 4 mol% of potassium trifluoroacetate. The stabilizing halide salt is zinc chloride, and the amount of zinc chloride added is 0.5 mol% of potassium trifluoroacetate.

[0077] In step S3, 148g of potassium trifluoromethyl sulfinate was obtained, with a yield of 83.4% and a purity of 97%. Approximately 25g of potassium trifluoroacetate was also obtained, with a purity of 97%.

[0078] The other parts are the same as in Example 1.

[0079] Comparative Example 1

[0080] In step S2, the acetonitrile has a water content of 2000 ppm; the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:1.5; the initiating halide salt is potassium fluoride, and the amount of potassium fluoride added is 20 mol% of potassium trifluoroacetate; the phase transfer catalyst is tetrabutylammonium bromide, and the amount of tetrabutylammonium bromide added is 4 mol% of potassium trifluoroacetate; the stabilizing halide salt is zinc chloride, and the amount of zinc chloride added is 0.5 mol% of potassium trifluoroacetate.

[0081] In step S3, 72g of potassium trifluoromethyl sulfinate was obtained, with a yield of 30.5% and a purity of 73%. Approximately 65g of potassium trifluoroacetate was also obtained, with a purity of 97%.

[0082] The other parts are the same as in Example 5.

[0083] Comparative Example 2

[0084] In step S2, the solvent is DMF, the DMF has a water content of 50 ppm, the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:1.5, the initiating halide salt is potassium fluoride, the amount of potassium fluoride added is 20 mol% of potassium trifluoroacetate, the phase transfer catalyst is tetrabutylammonium bromide, the amount of tetrabutylammonium bromide added is 4 mol% of potassium trifluoroacetate, and the stabilizing halide salt is zinc chloride, the amount of zinc chloride added is 0.5 mol% of potassium trifluoroacetate.

[0085] In step S3, 0g of potassium trifluoromethyl sulfinate was obtained, with a yield of 0% and a purity of 0%.

[0086] The other parts are the same as in Example 5.

[0087] Comparative Example 3

[0088] In step S2, no composite catalyst is added.

[0089] In step S3, 0g of potassium trifluoromethyl sulfinate was obtained, with a yield of 0% and a purity of 0%.

[0090] The reaction conditions and potassium trifluoromethyl sulfinate results for step S2 in Examples 1-5 and Comparative Examples 1-3 are shown in Table 1.

[0091] Table 1

[0092] in conclusion:

[0093] Examples 1-5 and Comparative Example 3 demonstrate that when an initiating halide salt, a stabilizing halide salt, and a phase transfer catalyst are present together, the reaction can proceed with high yield, low side reaction, and high product purity.

[0094] Example 5, compared with Comparative Example 1, illustrates that the water content of the solvent affects the occurrence of the reaction. Although the reaction can proceed with a high water content in the solvent, it cannot be separated during the purification process, resulting in a low yield.

[0095] Example 5, compared with Comparative Example 2, shows that although DMF has better solubility for potassium trifluoroacetate and can react with acetonitrile, it cannot separate the product and cannot obtain the final product.

[0096] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing potassium trifluoromethyl sulfinate, characterized in that, Includes the following steps: S1: Trifluoroacetic acid and potassium hydroxide are neutralized to obtain potassium trifluoroacetate; S2: Using sulfur dioxide as the sulfinizing agent and acetonitrile as the solvent, potassium trifluoroacetate is added, and potassium trifluoromethyl sulfinate is obtained through decarboxylation-sulfinization under the action of a composite catalyst, resulting in a mixed solution containing potassium trifluoromethyl sulfinate; the composite catalyst is a halide salt and a phase transfer catalyst, which initiates the reaction through the halide salt while reducing the side reactions, and works synergistically with the phase transfer catalyst to enable gas-phase, solid-phase, and liquid-phase reactions, thereby lowering the reaction temperature, increasing the reaction rate, and improving the product yield; S3: Then, the mixed solution containing potassium trifluoromethyl sulfinate is desolvated, cooled, and centrifuged to obtain potassium trifluoromethyl sulfinate.

2. The method for preparing potassium trifluoromethyl sulfinate as described in claim 1, characterized in that, The S2 step is specifically as follows: S21: Under stirring conditions, potassium trifluoroacetate powder is added to acetonitrile to obtain a raw material solution; S22: Add the composite catalyst to the raw material liquid to dissolve it, then draw a negative pressure and replace it with nitrogen to obtain the reaction solution; S23: Sulfur dioxide is introduced into the reaction solution and kept at 80℃-90℃ for 2h-3h to obtain a reaction solution containing potassium trifluoromethyl sulfinate.

3. The method for preparing potassium trifluoromethyl sulfinate as described in claim 2, characterized in that, The acetonitrile, sulfur dioxide, and composite catalyst have a water content of less than 50 ppm.

4. The method for preparing potassium trifluoromethyl sulfinate as described in claim 1 or 3, characterized in that, The reaction pressure is 0.15 MPa - 0.3 MPa.

5. The method for preparing potassium trifluoromethyl sulfinate as described in claim 3, characterized in that, In step S2, the molar ratio of potassium trifluoroacetate to sulfur dioxide is 1:1-3.

6. The method for preparing potassium trifluoromethyl sulfinate as described in claim 5, characterized in that, The halosalts include initiating halosalts and stable reactive halosalts.

7. The method for preparing potassium trifluoromethyl sulfinate as described in claim 6, characterized in that, The amount of the initiating halide salt is 15-25 mol of potassium trifluoroacetate, the amount of the phase transfer catalyst is 3-5 mol of potassium trifluoroacetate, and the amount of the stabilizing halide salt is 0.5-2 mol of potassium trifluoroacetate.

8. The method for preparing potassium trifluoromethyl sulfinate as described in claim 7, characterized in that, The initiating halide is one or more of potassium iodide, potassium fluoride, potassium bromide, cuprous bromide, and cuprous iodide.

9. The method for preparing potassium trifluoromethyl sulfinate as described in claim 6, characterized in that, The stable reactive halide salt is one or more of aluminum trichloride, ferric chloride, zinc chloride, and tin chloride.

10. The method for preparing potassium trifluoromethyl sulfinate as described in claim 8, characterized in that, In step S1, the temperature of the neutralization reaction is below 35°C, and the reaction time is 3-8 hours.

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