Synthesis method of electronic-grade hexafluorobutadiene

Abstract

A synthesis method of electronic-grade hexafluorobutadiene comprises the following steps: adding alkali, a phosphino ligand, a catalyst and an organic solvent into a reaction container, adding a stannane coupling reagent under the protection of inert gas, then cooling a reaction kettle, then adding halogenated trifluoroethylene, heating the reaction kettle, maintaining the reaction time for 2-24 hours, and after the reaction is finished, cooling the reaction kettle to obtain the electronic-grade hexafluorobutadiene. According to the method, a one-step coupling method is adopted, operation is easy and convenient, the problems of yield loss and separation of multi-step synthesis are solved, reaction conditions are mild, energy consumption is low, byproducts are few, high-selectivity conversion can be achieved through an optimized catalytic system, and the method is suitable for industrial production. Meanwhile, the raw materials are easy to obtain, the three wastes are few, and the industrial application potential is remarkable.

Description

Technical Field

[0001] This invention relates to the field of specialty gas synthesis technology, and in particular to a method for synthesizing electronic-grade hexafluorobutadiene. Background Technology

[0002] Hexafluorobutadiene (C4F6) is an important fluorinated specialty gas in semiconductor manufacturing processes, widely used as a novel green electronic etching gas. It possesses characteristics such as high etching precision, large aspect ratio, and excellent anisotropy, enabling near-vertical micro-etching, providing a key solution for manufacturing small-volume, high-capacity 3D NAND flash memory. Regarding environmental performance, as shown in Table 1, hexafluorobutadiene has a global warming potential (GWP) of only 290 and an atmospheric lifetime of 1.9 days, far lower than traditional fluorinated etching gases such as tetrafluoromethane, hexafluoroethane, octafluoropropane, and octafluorocyclobutane. It is one of the very few fluorinated electronic gases that combines excellent etching performance with outstanding environmental characteristics. Furthermore, this compound can also be used as a monomer to synthesize novel fluororesins and fluororubbers, showing broad market application prospects.

[0003] Table 1: GWP of each substance 100 and atmospheric lifetime information

[0004] Currently, there are many research methods for preparing hexafluorobutadiene, but its large-scale application is still limited by the lack of efficient, green, and scalable synthetic processes. Although several preparation routes have been reported, they generally suffer from problems such as harsh reaction conditions, serious environmental pollution, poor atom economy, or low industrial feasibility. The existing mainstream synthetic routes and their limitations are as follows:

[0005] 1. Mercury-catalyzed method: US3046304 discloses a method for dimerizing trifluorochloroethylene (CTFE, CF2=CHCl) into C4F6 under mercury salt catalysis. Although this route avoids the high temperature and high pressure conditions for telomerization, it requires the use of highly toxic mercury and produces mercuric iodide as a byproduct, which poses a great threat to the environment and operational safety.

[0006] 2. HFC-134a Dehalogenation Method: The Burton research group (Tetrahedron Lett., 2002, 43, 2731) and Beijing Yuji Technology Development Co., Ltd.'s patent CN104844411A disclosed a method for preparing hexafluorobutadiene using HFC-134a as a raw material. However, HFC-134a itself has an extremely high GWP value (>1000), and is a substance controlled by international conventions such as the Kigali Amendments, thus its use is restricted.

[0007] 3. Multi-step conversion method: Sinochem Lantian Group Co., Ltd. patent CN116120146B discloses a multi-step synthesis method, including hydrogenation reduction of trifluorochloroethylene, bromination, alkali treatment, zinc reagent preparation, and final coupling. This method is lengthy, and the self-coupling process requires two molecules of zinc reagent to generate one molecule of the target product, resulting in poor atom economy and low yield per unit volume. Furthermore, the excessive use of coupling catalyst increases raw material costs and the burden of solid waste treatment.

[0008] 4. High-Temperature Pyrolysis Method: Guangdong Huatai Gas Co., Ltd.'s patent CN116283481A proposes a route for high-temperature dimerization of trifluorochloroethylene followed by zinc dechlorination; Nanjing University Optoelectronics' patent CN116422236A and Sanai Fu New Materials Co., Ltd.'s patent CN104496748A respectively report schemes for preparing 3,4-dichlorohexafluoro-1-butene through high-temperature pyrolysis of trifluorochloroethylene, followed by further synthesis of hexafluorobutadiene. Although these methods shorten the steps, the reaction temperature is high, there are many side reactions, the products are complex and difficult to purify, resulting in unsatisfactory final yields.

[0009] 5. Halogen Addition Method: Patent publication number CN112250541A reports a multi-step synthetic route involving the addition of trifluorochloroethylene to iodine chloride, followed by zinc powder coupling and dechlorination. This process suffers from problems such as high solvent and zinc powder consumption, poor reaction selectivity, and low intermediate yield, making industrial scale-up extremely difficult.

[0010] Although there has been some research on the synthesis of hexafluorobutadiene, existing technologies generally suffer from prominent problems such as high toxicity, high energy consumption, cumbersome steps, heavy pollution, and limited raw materials, which seriously restrict its application in the field of high-end electronic chemicals. There is a need to develop a new synthetic route that is simple, efficient, environmentally friendly, and has the potential for industrial scale-up. Summary of the Invention

[0011] This invention avoids the need for multiple reaction steps required by traditional routes, and provides a novel one-pot coupling route based on a tinane-palladium catalytic system. This method enables the direct coupling of trifluoroethylene haloside to produce electronic-grade hexafluorobutadiene in a single reactor. The method includes the following steps: adding a base, phosphine-based ligand, palladium catalyst, and organic solvent to a reaction vessel; adding a coupling agent under inert gas protection; cooling the reaction vessel; adding trifluoroethylene haloside; heating the reaction vessel; maintaining the reaction time for 2–24 hours; after the reaction, cooling the system; performing conventional washing and separation; collecting the organic layer; and obtaining the target product, hexafluorobutadiene, through distillation.

[0012] Furthermore, the palladium-based catalyst is selected from at least one of the following: palladium dichloride, tetra(triphenylphosphine)palladium, [1,1'-bis(diphenylphosphine)ferrocene]palladium(II), bis(triphenylphosphine)palladium(II), 1,3-bis(diphenylphosphine)propanepalladium(II), tris(dibenzylideneacetone)palladium, palladium nitrate, palladium acetate, [(2-dimethylamino)propyldiphenylphosphine]palladium(II), dichloro[9,9-dimethyl-4,5-bis(diphenylphosphine)oxanthracene]palladium(II), and palladium catalyst supported on activated carbon.

[0013] Furthermore, the coupling reagent is a tin alkyl coupling reagent, selected from any one of tributyltin hydride, hexabutyltin, and hexamethyltin.

[0014] Furthermore, the alkali is used to neutralize the hydrogen halide released during the reaction or to promote the metallization step, preferably an inorganic fluoride selected from sodium fluoride, potassium fluoride, and cesium fluoride.

[0015] Furthermore, the organic solvent is selected from toluene, chlorobenzene, dichloromethane, 1,2-dichloroethane, carbon tetrachloride, tetrahydrofuran, diethylene glycol dimethyl ether, 1,4-dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, etc. N At least one of the following: methylpyrrolidone, dimethyl sulfoxide (DMSO), hexamethylphosphoric triamine, acetonitrile, xylene, etc.

[0016] Furthermore, the halogenated trifluoroethylene can be selected from one of the electron-deficient groups such as trifluorochloroethylene, trifluorobromoethylene, trifluoroiodoethylene, trifluoro(trifluorosulfonic acid)ethylene, trifluoro(methanesulfonic acid)ethylene, and trifluoro(toluenesulfonic acid)ethylene.

[0017] Furthermore, the catalyst coordinates with a phosphine-based ligand to form an active catalyst.

[0018] Furthermore, the phosphine ligand is selected from, but not limited to, triphenylphosphine, tri-tert-butylphosphine, tri(o-tolyl)phosphine, tricyclohexylphosphine, 1,3-bis(diphenylphosphine)propane, 1,3-bis(di-isopropylphosphine)propane, bis(diphenylphosphine)ferrocene, trifuranylphosphine, tri(pentafluorophenyl)phosphine, tri(2,4,6-trimethoxyphenyl)phosphine, 1,2-bis(diphenylphosphine)ethane, 1,4-bis(diphenylphosphine)butane, 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 1,1'-binaphthyl-2,2'-bisdiphenylphosphine, etc.

[0019] Furthermore, the molar ratio of the phosphine ligand to the palladium catalyst is 0.1:1 to 5.0:1, preferably 1:1 to 3:1.

[0020] Furthermore, the catalyst can also promote the metallization rate by adding a copper compound, wherein the copper compound is selected from any one of cuprous chloride, cuprous bromide, cuprous iodide, cuprous oxide, cuprous cyanide, or cuprous acetate.

[0021] Furthermore, the amount of copper compound used is 0.1 to 10 mol.

[0022] Furthermore, the molar ratio of the coupling agent to the halotrifluoroethylene is 0.5:1 to 3:1, preferably 0.6:1 to 2:1.

[0023] Furthermore, the molar ratio of the catalyst to halotrifluoroethylene is 0.01 to 10 mol%, preferably 1 to 5 mol.

[0024] Furthermore, the reaction temperature range is from room temperature to 250°C, preferably from 50°C to 200°C, and more preferably from 80°C to 150°C.

[0025] The beneficial effects of this invention are as follows: Compared with the prior art, this invention has significant advantages. It utilizes a tin ane and palladium catalytic system for coupling catalysis to achieve a one-pot coupling direct synthesis of hexafluorobutadiene from halogenated trifluoroethylene. The one-step coupling method simplifies the operation steps and avoids intermediate separation and yield loss in multi-step synthesis. The reaction temperature is significantly lower than that of high-temperature cracking or dimerization routes, resulting in low energy consumption and fewer side reactions and impurities. The entire process does not use high-risk metal reagents and does not generate ODPs or high GWP byproducts, conforming to the principles of green chemistry. The optimized catalytic system achieves highly selective conversion, and the product can be obtained in high yield and high purity after simple post-processing, meeting the requirements of electronic-grade gas. At the same time, the raw materials are readily available, the operation is simple, and there is little waste, demonstrating outstanding potential for industrial application. Attached Figure Description

[0026] Figure 1 This is a diagram illustrating the reaction mechanism of hexafluorobutadiene in this invention. Detailed Implementation

[0027] To explain in detail the possible application scenarios, technical principles, specific feasible solutions, and the objectives and effects that this application can achieve, the following detailed description is provided in conjunction with the specific embodiments listed.

[0028] The embodiments described in this invention are only used to illustrate the technical solutions of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0029] In this invention, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form a corresponding implementable technical solution.

[0030] Unless otherwise defined, the technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms in this invention is merely for describing specific embodiments and is not intended to limit this application.

[0031] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, in this invention, the character " / " generally indicates that the preceding and following objects have an "or" logical relationship.

[0032] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0033] Unless otherwise specified, the use of terms such as “comprising,” “including,” “having,” or other similar expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0034] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0035] A method for synthesizing electronic-grade hexafluorobutadiene includes the following steps: adding a base, a phosphine ligand, a catalyst, and an organic solvent to a reaction vessel; adding a tinane coupling reagent under inert gas protection; subsequently cooling the reaction vessel; adding halotrifluoroethylene; heating the reaction vessel; maintaining the reaction time for 2–24 hours; after the reaction is complete, cooling the system; performing routine washing and separation; collecting the organic layer; and obtaining the target product, hexafluorobutadiene, by distillation. The general reaction formula for this method is shown below:

[0036] in, X It can be -Cl (trifluorochloroethylene), -Br (trifluorobromoethylene), or -I (trifluoroiodoethylene), -OTf (trifluoro(trifluorosulfonic acid)ethylene), -OMs (trifluoro(methanesulfonic acid)ethylene), or -OTs (trifluoro(toluenesulfonic acid)ethylene).

[0037] In some implementations, the catalyst is Palladium series The catalyst is selected from at least one of the following: including palladium dichloride ( PdCl 2 ), tetra(triphenylphosphine)palladium ( Pd(PPh 3 ) 4 [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride PdCl 2 (dppf) ), di(triphenylphosphine)palladium(II) chloride PdCl 2 (PPh 3 ) 2) 1,3-bis(diphenylphosphine)propane palladium(II) chloride (PdCl 2 (dppp)) Tris(dibenzylacetone)dipalladium ( Pd 2 (dba) 3) Palladium nitrate ( Pd(NO 3 ) 2) Palladium acetate ( Pd (OAc) 2) [(2-Dimethylamino)propyldiphenylphosphine]palladium(II) chloride PdCl 2 (alaPhos) ), dichloro[9,9-dimethyl-4,5-bis(diphenylphosphine)oxanthracene]palladium(II) (PdCl 2 (XantPhos)) Activated carbon supported palladium catalyst ( Pd / C Any one of the above catalysts can generate active zero-valent palladium Pd in ​​situ under heating and reduction conditions. (0) This initiates the catalytic cycle.

[0038] In some embodiments, the tin alkyl coupling agent is selected from any one of tributyltin hydride (HSnBu3), hexabutyltin ditin (Sn2Bu6), and hexamethyltin ditin (Sn2Me6).

[0039] In some embodiments, the base is used to neutralize the hydrogen halide released during the reaction or to promote the transmetallization step, preferably an inorganic fluoride selected from any one of sodium fluoride (NaF), potassium fluoride (KF), or cesium fluoride (CsF).

[0040] In some embodiments, the organic solvent is selected from at least one of toluene, chlorobenzene (PhCl), dichloromethane (DCM), 1,2-dichloroethane (DCE), carbon tetrachloride (CCl4), tetrahydrofuran (THF), diethylene glycol dimethyl ether (Diglyme), 1,4-dioxane, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), hexamethylphosphoric triamine (HMPA), acetonitrile (ACN), xylene, etc.

[0041] In some embodiments, the halogenated trifluoroethylene may be selected from one of the electron-deficient groups such as trifluorochloroethylene, trifluorobromoethylene, trifluoroiodoethylene, trifluoro(trifluorosulfonic acid)ethylene, trifluoro(methanesulfonic acid)ethylene, and trifluoro(toluenesulfonic acid)ethylene.

[0042] In some embodiments, the catalyst is coordinated with a phosphine-based ligand to form an active catalyst, wherein the molar ratio of the phosphine ligand to the palladium catalyst is 0.1:1 to 5.0:1, preferably 1:1 to 3:1. The appropriate addition of the phosphine ligand helps to regulate electronic effects and steric hindrance, thereby improving reaction efficiency.

[0043] In some embodiments, the phosphine-based ligands include, but are not limited to: triphenylphosphine (PPh3), tri-tert-butylphosphine (P... t Bu3), tri(o-tolyl)phosphine (P( o-tol)3), tricyclohexylphosphine (PCy3), 1,3-bis(diphenylphosphine)propane (dppp), 1,3-bis(di-isopropylphosphine)propane (dippp), bis(diphenylphosphine)ferrocene (dppf), trifuranylphosphine (P(2-Fur)3), tris(pentafluorophenyl)phosphine (P(C5F5)3), tris(2,4,6-trimethoxyphenyl)phosphine (P(2,4,6-(OMe)3C6H2)3), 1,2-bis(diphenylphosphine)ethane (DPPE), 1,4-bis(diphenylphosphine)butane (DPPB), 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene (Xantphos), 1,1'-binaphthyl-2,2'-bisdiphenylphosphine (BINAP), etc., wherein the molar ratio of the phosphine ligand to the palladium catalyst is from 0.1:1 to 5.0:1, preferably from 1:1 to 3:1.

[0044] In some embodiments, the catalyst can also promote the metallization rate by adding a copper compound selected from any one of cuprous chloride (CuCl), cuprous bromide (CuBr), cuprous iodide (CuI), cuprous oxide (Cu2O), cuprous cyanide (CuCN), or cuprous acetate (CuOAc). The amount of copper compound used is 0.1 to 10 mol%, which can effectively improve the overall performance without affecting the main catalytic system.

[0045] In some embodiments, the molar ratio of the coupling agent to halotrifluoroethylene is 0.5:1 to 3:1, preferably 0.6:1 to 2:1.

[0046] In some embodiments, the molar ratio of catalyst to halotrifluoroethylene is 0.01 to 10 mol%, preferably 1 to 5 mol.

[0047] In some embodiments, the reaction temperature ranges from room temperature to 250°C, preferably from 50°C to 200°C, and more preferably from 80°C to 150°C.

[0048] In some embodiments, the reaction can be carried out in an oil bath or heating mantle under the protection of nitrogen or an inert atmosphere, and the reaction time is generally 2–24 hours, depending on the substrate activity and catalyst system.

[0049] Combination Figure 1 The synthesis reaction mechanism of the present invention is further explained as shown.

[0050] Catalyst activation: Palladium precursors (such as Pd(PPh3)4, Pd2(dba)3, Pd(OAc)2, etc.) are converted into active zero-valent palladium species Pd(0) upon heating.

[0051] Step 1: Perform the first oxidative addition reaction, active Pd (0)In cyclophosphide halotrifluoroethylene (CF2=CF=X), CX forms a cis-addition intermediate, which then rearranges to a more stable trans configuration, with palladium from Pd (0) Upgraded to Pd (II) This forms CF2=CF-Pd (II) -X complexes.

[0052] Example: Pd (0) +CF2=CF-Cl→CF2=CF-Pd (II) -Cl

[0053] Step 2: Perform the first metallization, CF2 = CF - Pd (II) -X complexes undergo transfer metallization with tinane reagents to form CF2=CF-Pd (II) -SnBu3, and releases the byproduct R ’ Cl.

[0054] Example: CF2 = CF - Pd (II) -Cl+R ’ -SnR3→CF2=CF-Pd (II) -SnBu3+R ’ Cl

[0055] Side reaction: Chlorine removal occurs, R ’ The Cl byproduct reacts with MF to produce R. ’ F and inert precipitate MCl improve the efficiency of the transfer metallization step.

[0056] Example: R ’ Cl+MF→R ’ F+MCl

[0057] Step 3: The first reductive elimination occurs, where the CF2=CF- group and the R3Sn- group undergo reductive elimination to generate the transition product R3Sn-CF=CF2, while simultaneously regenerating Pd. (0) .

[0058] Example: CF2 = CF - Pd (II) -SnBu3→CF2=CF-SnR3+Pd (0)

[0059] Step 4a: Activation of the tin intermediate: CF2=CF-SnR3 reacts with the activator MF to form a highly nucleophilic five-coordinate stannate anion [CF2=CF-SnR3F]. - + M accelerates the metallization transfer process.

[0060]

[0061] Example: CF2=CF-SnR3+MF→[CF2=CF-SnR3F] - + M

[0062] Step 4b: Activation of the tin intermediate is performed. CF2=CF-SnR3 reacts with the activator CuX to form highly nucleophilic CF2=CF-Cu. (I) This accelerates the metallization transfer process.

[0063]

[0064] Example: CF2=CF-SnR3+CuX→[CF2=CF-Cu (I) ]+SnR3X

[0065] Step 5: Perform a second transfer metallization, repeating the process from Step 1 to obtain CF2 = CF - Pd (II) The -Cl complex is then subjected to a transfer metallization reaction with the activated intermediate obtained in step 4a or 4b, transferring its alkenyl moiety to the palladium center to complete the second transfer metallization, forming divinyl-Pd. (II) Intermediate.

[0066] Example: CF2 = CF - Pd (II) -Cl+[CF2=CF-SnR3F] - + M→CF2=CF-Pd (II) -CF=CF2+R3SnCl+MX

[0067] Example: CF2 = CF - Pd (II) -Cl+[CF2=CF-Cu (I) →CF2=CF-Pd (II) -CF=CF2+R3SnCl+CuX

[0068] Step 6: Perform a second reduction elimination, bisvinyl-Pd (II) The two organic groups on the intermediate undergo intramolecular coupling to form a new C(sp) 2 )-C(sp 2 The F2C=CF-CF=CF2 bond is formed to generate the target product hexafluorobutadiene (F2C=CF-CF=CF2), while releasing Pd. (0) Then proceed to the next cycle.

[0069] Example: CF2 = CF - Pd (II) -CF=CF2→CF2=CF-CF=CF2+Pd (0)

[0070] The following are specific implementation experimental examples for verification, which are only used as preferred options to illustrate and verify the process and technical effects of the above preparation process.

[0071] Example 1: Potassium fluoride (KF) (4.65 g, 80 mmol, 0.80 eq), 1,3-bis(diphenylphosphine)propane (dppp) (0.825 g, 2.0 mmol, 2.0 eq), tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) (1.156 g, 1.0 mmol, 1.0 mol%), and 150 mL of anhydrous diethylene glycol dimethyl ether (Diglyme) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (23.02 g, 70 mmol, 0.70 eq) was slowly added. The reactor was then cooled to -10 °C, followed by the addition of trifluoroiodide (20.89 g, 100 mmol, 1.00 eq). The reactor was heated to 110 °C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and after routine washing and separation, the organic layer was taken and then distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.75%. Based on trifluoroiodide ethylene, the yield of hexafluorobutadiene was calculated to be 82%.

[0072] Example 2: Potassium fluoride (KF) (10.46 g, 180 mmol, 1.80 eq), triphenylphosphine (PPh3) (0.944 g, 3.6 mmol, 3.6 eq), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride (PdCl2(dppf)) (2.202 g, 3.0 mmol, 3.0 mol%), and 150 mL of anhydrous chlorobenzene (PhCl) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexabutylbistinane (Sn2Bu6) (58.08 g, 100 mmol, 1.00 eq) was slowly added. The reactor was then cooled to -10 °C, and trifluorobromoethylene (16.09 g, 100 mmol, 1.00 eq) was added. The reactor was heated to 130°C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and after routine washing and separation, the organic layer was collected. After distillation, the target product, hexafluorobutadiene, was obtained with a purity of 99.02%. Based on trifluorobromoethylene, the yield of hexafluorobutadiene was calculated to be 78%.

[0073] Example 3: Potassium fluoride (KF) (3.49 g, 60 mmol, 0.60 eq), tricyclohexylphosphine (PCy3) (1.122 g, 4.0 mmol, 4.0 eq), tris(dibenzylacetone)dipalladium (Pd2(dba)3) (3.663 g, 4.0 mmol, 4.0 mol%), and 150 mL of anhydrous N,N-dimethylformamide (DMF) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (37.82 g, 115 mmol, 1.15 eq) was slowly added. The reactor was then cooled to -10 °C, and trifluoroiodide (20.89 g, 100 mmol, 1.00 eq) was added. The reactor was heated to 130 °C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and after routine washing and separation, the organic layer was taken and then distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.33%. Based on trifluoroiodide, the yield of hexafluorobutadiene was calculated to be 72%.

[0074] Example 4: Potassium fluoride (KF) (3.20 g, 55 mmol, 0.55 eq) and tri-tert-butylphosphine (P) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. t Bu3 (1.416 g, 7.0 mmol, 7.0 eq), tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) (4.045 g, 3.5 mmol, 3.5 mol%), and 150 mL of anhydrous acetonitrile (ACN) were added. Under nitrogen protection, trimethylstanane (HSnMe3) (28.02 g, 170 mmol, 1.7 eq) was slowly added, followed by cooling the reactor to -10°C, and then adding trifluoro(methanesulfonic acid)ethylene (21.42 g, 100 mmol, 1.00 eq). The reactor was then heated to 75°C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and after routine washing and separation, the organic layer was collected and purified by distillation to obtain the target product, hexafluorobutadiene, with a purity of 98.90%. Based on trifluoro(methanesulfonic acid)ethylene, the yield of hexafluorobutadiene was calculated to be 62%.

[0075] Example 5: Potassium fluoride (KF) (5.52 g, 95 mmol, 0.95 eq), trifuranylphosphine (P(2-Fur)3) (2.504 g, 9.0 mmol, 9.0 eq), dichloro[9,9-dimethyl-4,5-bis(diphenylphosphine)oxanthracene]palladium(II) (PdCl2(XantPhos)) (3.275 g, 4.5 mmol, 4.5 mol%), and 150 mL of anhydrous toluene were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexabutylbistanane (Sn2Bu6) (52.27 g, 90 mmol, 0.90 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluorochloroethylene (11.65 g, 100 mmol, 1.00 eq). The reactor was heated to 105°C and the reaction was maintained for 20 hours. After the reaction, the system was cooled, and the organic layer was collected after routine washing and separation. The organic layer was then distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.58%. Based on trifluorochloroethylene, the yield of hexafluorobutadiene was calculated to be 70%.

[0076] Example 6: Potassium fluoride (KF) (9.30 g, 160 mmol, 1.60 eq), tris(2,4,6-trimethoxyphenyl)phosphine (1.370 g, 3.6 mmol, 3.6 eq), palladium dichloride (PdCl2) (0.319 g, 1.8 mmol, 1.8 mol%), and 150 mL of anhydrous N,N-dimethylacetamide (DMAc) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Hexabutyldistannane (Sn2Bu6) (60.99 g, 105 mmol, 1.05 eq) was slowly added under nitrogen protection. The reactor was then cooled to -10°C, and trifluoro(trifluorosulfonic acid)ethylene (25.01 g, 100 mmol, 1.00 eq) was added. The reactor was heated to 100°C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and after routine washing and separation, the organic layer was taken and then distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.88%. Based on trifluoro(trifluorosulfonic acid)ethylene, the yield of hexafluorobutadiene was calculated to be 83%.

[0077] Example 7: Potassium fluoride (KF) (6.39 g, 110 mmol, 1.10 eq), 1,4-bis(diphenylphosphino)butane (DPPB) (3.751 g, 8.4 mmol, 8.4 eq), bis(triphenylphosphine)palladium(II) chloride (PdCl2(PPh3)2) (2.948 g, 4.2 mmol, 4.2 mol%), and 150 mL of anhydrous N-methylpyrrolidone (NMP) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (30.25 g, 92 mmol, 0.92 eq) was slowly added. The reactor was then cooled to -10 °C, and trifluoroiodide (20.89 g, 100 mmol, 1.00 eq) was added. The reactor was heated to 95°C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and the organic layer was collected after routine washing and separation. The organic layer was then distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.95%. Based on trifluoroiodide, the yield of hexafluorobutadiene was calculated to be 85%.

[0078] Example 8: Potassium fluoride (KF) (10.75 g, 185 mmol, 1.85 eq), triphenylphosphine (PPh3) (0.577 g, 2.2 mmol, 2.2 eq), tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) (2.542 g, 2.2 mmol, 2.2 mol%), and 150 mL of anhydrous N,N-dimethylacetamide (DMAc) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Hexabutyldistannane (Sn2Bu6) (34.85 g, 60 mmol, 0.60 eq) was slowly added under nitrogen protection. The reactor was then cooled to -10 °C, followed by the addition of trifluorochloroethylene (11.65 g, 100 mmol, 1.00 eq). The reactor was heated to 165 °C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and after routine washing and separation, the organic layer was taken and then distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.11%. Based on trifluorochloroethylene, the yield of hexafluorobutadiene was calculated to be 55%.

[0079] Example 9: Potassium fluoride (KF) (7.84 g, 135 mmol, 1.35 eq), 1,3-bis(di-isopropylphosphine)propane (dippp) (0.921 g, 2.5 mmol, 2.5 eq), palladium nitrate (Pd(NO3)2) (0.230 g, 1.0 mmol, 1.0 mol%), and 150 mL of anhydrous dichloromethane (DCM) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Hexabutylbistinane (Sn2Bu6) (72.60 g, 125 mmol, 1.25 eq) was slowly added under nitrogen protection. The reactor was then cooled to -10 °C, and trifluorobromoethylene (16.09 g, 100 mmol, 1.00 eq) was added. The reactor was heated to 30 °C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and after routine washing and separation, the organic layer was taken and then distilled to obtain the target product hexafluorobutadiene with a purity of 98.86%. Based on trifluorobromoethylene, the yield of hexafluorobutadiene was calculated to be 60%.

[0080] Example 10: Potassium fluoride (KF) (9.00 g, 155 mmol, 1.55 eq), tris(pentafluorophenyl)phosphine (P(C6F5)3) (2.227 g, 4.2 mmol, 4.2 eq), tris(dibenzylacetone)palladium (Pd2(dba)3) (1.282 g, 1.4 mmol, 1.4 mol%), and 150 mL of anhydrous xylene were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (52.61 g, 160 mmol, 1.60 eq) was slowly added. The reactor was then cooled to -10 °C, and trifluorobromoethylene (16.09 g, 100 mmol, 1.00 eq) was added. The reactor was heated to 130°C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and after routine washing and separation, the organic layer was collected. After distillation, the target product, hexafluorobutadiene, was obtained with a purity of 99.25%. Based on trifluorobromoethylene, the yield of hexafluorobutadiene was calculated to be 75%.

[0081] Example 11: Potassium fluoride (KF) (6.97 g, 120 mmol, 1.20 eq) and tri-tert-butylphosphine (P) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. tThe reaction mixture consisted of: Bu3 (0.607 g, 3.0 mmol, 3.0 eq), palladium dichloride (PdCl2) (0.266 g, 1.5 mmol, 1.5 mol%), cuprous iodide (CuI) (0.952 g, 5.0 mmol, 5.0 mol%), and 150 mL of anhydrous N,N-dimethylacetamide (DMAc). Under nitrogen protection, hexabutylbistanne (Sn2Bu6) (49.37 g, 85 mmol, 0.85 eq) was slowly added. The reaction vessel was then cooled to -10°C, and trifluorochloroethylene (CF2=CFCl) (11.65 g, 100 mmol, 1.00 eq) was added. The reaction vessel was then heated to 160°C and the reaction was maintained for 20 hours. After the reaction was completed, the system was cooled, and the organic layer was taken after routine washing and separation. After distillation, the target product hexafluorobutadiene was obtained with a purity of 99.63%. Based on trifluorochloroethylene (CF2=CFCl), the yield of hexafluorobutadiene was calculated to be 80%.

[0082] Example 12: Potassium fluoride (KF) (5.81 g, 100 mmol, 1.00 eq), 1,3-bis(di-isopropylphosphine)propane (dippp) (1.658 g, 4.5 mmol, 4.5 eq), bis(triphenylphosphine)palladium(II) chloride (PdCl2(PPh3)2) (1.053 g, 1.5 mmol, 1.5 mol%), cuprous chloride (CuCl) (0.248 g, 2.5 mmol, 2.5 mol%), and 150 mL of anhydrous dimethyl sulfoxide (DMSO) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (31.24 g, 95 mmol, 0.95 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluoro(trifluorosulfonic acid)ethylene (25.01 g, 100 mmol, 1.00 eq). The reactor was heated to 85°C and the reaction was maintained for 20 hours. After the reaction, the system was cooled, and after routine washing and separation, the organic layer was collected. Distillation yielded the target product, hexafluorobutadiene, with a purity of 99.98%. Based on trifluoro(trifluorosulfonic acid)ethylene, the yield of hexafluorobutadiene was calculated to be 85%.

[0083] Example 13: Potassium fluoride (KF) (8.72 g, 150 mmol, 1.50 eq), tris(o-tolyl)phosphine (P(o-tol)3) (1.522 g, 5.0 mmol, 5.0 eq), 1,3-bis(diphenylphosphine)propane palladium(II) chloride (PdCl2(dppp)) (1.434 g, 2.5 mmol, 2.5 mol%), cuprous bromide (CuBr) (2.152 g, 15.0 mmol, 15.0 mol%), and 150 mL of anhydrous 1,2-dichloroethane (DCE) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, trimethylstanane (HSnMe3) (19.78 g, 120 mmol, 1.2 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluorochloroethylene (11.65 g, 100 mmol, 1.00 eq). The reactor was heated to 80°C and the reaction was maintained for 20 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected. Distillation yielded the target product, hexafluorobutadiene, with a purity of 99.41%. Based on trifluorochloroethylene, the yield of hexafluorobutadiene was calculated to be 65%.

[0084] Example 14: Potassium fluoride (KF) (11.33 g, 195 mmol, 1.95 eq), bis(diphenylphosphine)ferrocene (dppf) (3.327 g, 6.0 mmol, 6.0 eq), palladium nitrate (Pd(NO3)2) (0.461 g, 2.0 mmol, 2.0 mol%), cuprous cyanide (CuCN) (0.090 g, 1.0 mmol, 1.0 mol%), and 150 mL of anhydrous N-methylpyrrolidone (NMP) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexabutyldistinane (Sn2Bu6) (41.82 g, 72 mmol, 0.72 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluorobromoethylene (16.09 g, 100 mmol, 1.00 eq). The reactor was heated to 120°C and the reaction was maintained for 20 hours. After the reaction, the system was cooled, and the organic layer was collected after routine washing and separation. The organic layer was then distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.81%. Based on trifluorobromoethylene, the yield of hexafluorobutadiene was calculated to be 84%.

[0085] Example 15: Potassium fluoride (KF) (8.13 g, 140 mmol, 1.40 eq), 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene (Xantphos) (4.340 g, 7.5 mmol, 7.5 eq), palladium acetate (Pd(OAc)2) (1.123 g, 5.0 mmol, 5.0 mol%), cuprous acetate (CuOAc) (1.206 g, 10.0 mmol, 10.0 mol%), and 150 mL of anhydrous hexamethylphosphoric acid triamine (HMPA) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (49.33 g, 150 mmol, 1.50 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluorochloroethylene (11.65 g, 100 mmol, 1.00 eq). The reactor was heated to 175°C and the reaction was maintained for 20 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected. Distillation yielded the target product, hexafluorobutadiene, with a purity of 99.07%. Based on trifluorochloroethylene, the yield of hexafluorobutadiene was calculated to be 80%.

[0086] Example 16: Potassium fluoride (KF) (9.88 g, 170 mmol, 1.70 eq), triphenylphosphine (PPh3) (0.629 g, 2.4 mmol, 2.4 eq), 1,3-bis(diphenylphosphine)propane palladium(II) chloride (PdCl2(dppp)) (0.688 g, 1.2 mmol, 1.2 mol%), cuprous oxide (Cu2O) (1.002 g, 7.0 mmol, 7.0 mol%), and 150 mL of anhydrous 1,4-dioxane were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (59.19 g, 180 mmol, 1.80 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluoro(toluenesulfonic acid)ethylene (29.03 g, 100 mmol, 1.00 eq). The reactor was then heated to 100°C and the reaction was maintained for 20 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected. Distillation yielded the target product, hexafluorobutadiene, with a purity of 99.71%. Based on trifluoro(toluenesulfonic acid)ethylene, the yield of hexafluorobutadiene was calculated to be 83%.

[0087] Example 17: Potassium fluoride (KF) (7.55 g, 130 mmol, 1.30 eq), 1,2-bis(diphenylphosphino)ethane (DPPE) (3.515 g, 8.4 mmol, 8.4 eq), [(2-dimethylamino)propyldiphenylphosphine]palladium(II) chloride (PdCl2(alaPhos)) (1.321 g, 2.8 mmol, 2.8 mol%), cuprous iodide (CuI) (0.952 g, 5.0 mmol, 5.0 mol%), and 150 mL of anhydrous dimethyl sulfoxide (DMSO) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (28.85 g, 88 mmol, 0.88 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluorobromoethylene (16.09 g, 100 mmol, 1.00 eq). The reactor was heated to 145°C and the reaction was maintained for 20 hours. After the reaction, the system was cooled, and after routine washing and separation, the organic layer was collected. Distillation yielded the target product, hexafluorobutadiene, with a purity of 99.30%. Based on trifluorobromoethylene, the yield of hexafluorobutadiene was calculated to be 84%.

[0088] Example 18: Potassium fluoride (KF) (4.36 g, 75 mmol, 0.75 eq), 1,1'-binaphthyl-2,2'-bis(diphenylphosphine) (BINAP) (1.993 g, 3.2 mmol, 3.2 eq), palladium acetate (Pd(OAc)2) (0.718 g, 3.2 mmol, 3.2 mol%), cuprous chloride (CuCl) (0.198 g, 2.0 mmol, 2.0 mol%), and 150 mL of anhydrous N,N-dimethylformamide (DMF) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexabutyldistannane (Sn2Bu6) (44.14 g, 76 mmol, 0.76 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluorochloroethylene (11.65 g, 100 mmol, 1.00 eq). The reactor was heated to 150°C and the reaction was maintained for 20 hours. After the reaction, the system was cooled, and the organic layer was collected after routine washing and separation. The organic layer was then distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.52%. Based on trifluorochloroethylene, the yield of hexafluorobutadiene was calculated to be 75%.

[0089] Example 19: Potassium fluoride (KF) (4.94 g, 85 mmol, 0.85 eq), bis(diphenylphosphine)ferrocene (dppf) (4.214 g, 7.6 mmol, 7.6 eq), 1,3-bis(diphenylphosphine)propanepalladium(II) chloride (PdCl2(dppp)) (2.188 g, 3.8 mmol, 3.8 mol%), cuprous cyanide (CuCN) (0.358 g, 4.0 mmol, 4.0 mol%), and 150 mL of anhydrous tetrahydrofuran (THF) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (24.01 g, 73 mmol, 0.73 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluoro(trifluorosulfonic acid)ethylene (25.01 g, 100 mmol, 1.00 eq). The reactor was then heated to 60°C and the reaction was maintained for 20 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected. Distillation yielded the target product, hexafluorobutadiene, with a purity of 98.99%. Based on trifluoro(trifluorosulfonic acid)ethylene, the yield of hexafluorobutadiene was calculated to be 75%.

[0090] Example 20: Potassium fluoride (KF) (2.91 g, 50 mmol, 0.50 eq), 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene (Xantphos) (2.893 g, 5.0 mmol, 5.0 eq), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride (PdCl2(dppf)) (3.670 g, 5.0 mmol, 5.0 mol%), cuprous acetate (CuOAc) (0.121 g, 1.0 mmol, 1.0 mol%), and 150 mL of anhydrous carbon tetrachloride (CCl4) were added to a 300 mL high-pressure reactor equipped with a magnetic stirrer, pressure control valve, and thermometer. Under nitrogen protection, hexamethyldistinane (Sn2Me6) (65.77 g, 200 mmol, 2.00 eq) was slowly added. The reactor was then cooled to -10°C, followed by the addition of trifluorochloroethylene (11.65 g, 100 mmol, 1.00 eq). The reactor was heated to 70°C and the reaction was maintained for 20 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected. Distillation yielded the target product, hexafluorobutadiene, with a purity of 99.20%. Based on trifluorochloroethylene, the yield of hexafluorobutadiene was calculated to be 70%.

[0091] The proposed method for synthesizing hexafluorobutadiene utilizes a tin / palladium catalytic system and optimized reaction parameters, maintaining efficient reaction progress and excellent selectivity across various coupling reagents and a wide reaction temperature range. Experimental results show that the yield of hexafluorobutadiene synthesized by this method is no less than 55%, and the purity reaches over 98.8%.

[0092] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for synthesizing electronic-grade hexafluorobutadiene, characterized in that, The process includes the following steps: adding a base, phosphine ligand, palladium catalyst, and organic solvent to a reaction vessel; adding a coupling agent under inert gas protection; cooling the reaction vessel; adding halotrifluoroethylene; heating the reaction vessel; maintaining the reaction time for 2–24 hours; after the reaction is complete, cooling the system; performing routine washing and separation; taking the organic layer; and obtaining the target product hexafluorobutadiene through distillation.

2. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The coupling agent is a tinane-based coupling agent.

3. The method for synthesizing hexafluorobutadiene according to claim 2, characterized in that, The tin alkyl coupling reagent is selected from any one of tributyltin hydride, hexabutyltin, and hexamethyltin.

4. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The alkali is an inorganic fluoride, selected from any one of sodium fluoride, potassium fluoride, or cesium fluoride.

5. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The molar ratio of the phosphine ligand to the palladium catalyst is from 0.1:1 to 5.0:

1.

6. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, A catalyst is added to the reaction vessel, followed by the addition of a copper compound to accelerate the metallization rate. The copper compound is selected from any one of cuprous chloride, cuprous bromide, cuprous iodide, cuprous oxide, cuprous cyanide, or cuprous acetate.

7. The method for synthesizing hexafluorobutadiene according to claim 6, characterized in that, The amount of copper compound used is 0.1 to 10 mol.

8. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The molar ratio of the coupling reagent to halotrifluoroethylene is 0.5:1 to 3:

1.

9. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The molar ratio of catalyst to halotrifluoroethylene is 0.01 to 10 mol.

10. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The heating temperature range of the reactor is from room temperature to 250°C.

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