Synthetic method of hexafluorobutadiene

Abstract

The invention relates to a hexafluorobutadiene synthesis method, which comprises: adding an organic solvent, water, halogenated trifluoroethylene, a coupling reagent, a catalyst and an alkali into a reaction container at the same time, heating to carry out a coupling reaction, and after the reaction is completed, carrying out washing, extraction, drying and rectification post-treatment on the reaction liquid to obtain hexafluorobutadiene. The operation is simple and convenient, and the problems of yield loss and separation in multi-step synthesis are avoided. The method has the advantages of mild reaction conditions, low energy consumption, few by-products, realization of high-selectivity conversion through an optimized catalytic system, high product purity, easy post-treatment, easily available raw materials, few three wastes, and substantial industrial application potential.

Description

Technical Field

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

[0002] Hexafluorobutadiene (C4F6), as a novel green electronic etching gas, has important applications in the field of semiconductor microfabrication, especially in the manufacture of 3D NAND flash memory. It possesses characteristics such as high etching precision, large aspect ratio, and excellent anisotropy, enabling near-vertical micro-pattern etching, meeting the current process requirements of integrated circuits for small-volume, high-capacity memory. In terms of environmental performance, hexafluorobutadiene has a global warming potential (GWP) of 290 and an atmospheric lifetime of only 1.9 days, far lower than traditional fluorinated etching gases such as tetrafluoromethane, hexafluoroethane, octafluoropropane, and octafluorocyclobutane, making it one of the fluorinated electronic specialty gases that combines excellent etching performance with environmental friendliness. Furthermore, this compound can also be used as a fluorinated monomer in the synthesis of high-performance fluororesins and fluororubbers, showing broad market prospects.

[0003] Currently, although various synthetic routes for hexafluorobutadiene have been reported, they generally suffer from process defects that hinder their industrial-scale promotion. For example:

[0004] Although the synthetic route using trifluorochloroethylene reported in US3046304 avoids high temperature and high pressure conditions, the reaction requires the use of highly toxic mercury and generates mercuric iodide as a byproduct, posing serious environmental and safety risks.

[0005] Burton et al. (Tetrahedron Lett., 2002, 43, 2731) and Beijing Yuji Patent CN104844411A proposed a synthesis scheme using HFC-134a as a raw material. However, HFC-134a has a GWP of over 1000 and is a controlled substance under the Kigali Amendment, thus restricting the use of the raw material.

[0006] Sinochem Lantian's patent CN116120146B employs a multi-step synthesis method, including hydrogenation reduction, bromination, alkali treatment, zinc reagent preparation and coupling, etc. The process is lengthy and has poor atom economy. Furthermore, the coupling step requires the consumption of two equivalents of zinc reagent, resulting in low unit production capacity and high solid waste treatment costs.

[0007] Guangdong Huatai's patent CN116283481A proposes a zinc dechlorination route after high-temperature dimerization of trifluorochloroethylene; Nanda Optoelectronics' CN116422236A and Sanaifu's CN104496748A report a method for high-temperature pyrolysis of trifluorochloroethylene to generate 3,4-dichlorohexafluoro-1-butene and then conversion. Although these routes have simplified steps, the reaction temperature is high, there are many side reactions, and the products are complex, resulting in unsatisfactory yield and purity.

[0008] The route reported in CN112250541A, which involves the addition of trifluorochloroethylene with iodine chloride followed by zinc powder coupling and dechlorination, suffers from problems such as high solvent and zinc powder consumption, poor selectivity, and low intermediate yield, making scale-up difficult.

[0009] In summary, existing methods for synthesizing hexafluorobutadiene mainly include:

[0010] (1) High-temperature pyrolysis method: fluorine-containing precursors are degraded at 650–900℃, which has high energy consumption, poor selectivity and many by-products.

[0011] (2) Metal reduction coupling method: The reaction uses metals such as zinc, magnesium, and mercury, which generates a large amount of metal salt waste, and the post-processing is complicated and the product purification is difficult.

[0012] (3) Multi-step synthesis route: It requires multiple steps such as intermediate preparation, dehalogenation, and coupling, which is lengthy and has high overall cost.

[0013] Extensive research has revealed no reports of a one-step synthesis of hexafluorobutadiene using a borate ester-Pd catalytic system for the direct two-stage coupling reaction of halotrifluoroethylene. Therefore, this invention proposes a novel synthetic route for hexafluorobutadiene that is simple in procedure, operates under mild conditions, is environmentally friendly, and suitable for industrial production. Summary of the Invention

[0014] In view of this, to overcome the above problems, this invention avoids the multi-step reaction required by traditional routes and provides a method for directly coupling trifluoroethylene halothoxylate to hexafluorobutadiene in a single reactor using borate ester coupling reagents and a palladium-based catalytic system. This method simplifies the process in one step, is suitable for large-scale industrialization, and the hexafluorobutadiene obtained by this method has the characteristics of high purity and high yield. The technical solution is as follows:

[0015] A method for synthesizing hexafluorobutadiene, characterized by comprising the following steps: simultaneously adding an organic solvent, water, halotrifluoroethylene, coupling reagent, catalyst and base to a reaction vessel, heating to carry out a coupling reaction, and after the reaction is completed, washing, extracting, drying and distilling the reaction solution to obtain hexafluorobutadiene.

[0016] Furthermore, organic solvents include toluene, dichloromethane, 1,2-dichloroethane, carbon tetrachloride, tetrahydrofuran (THF), diethylene glycol dimethyl ether, and 1,4-dioxane. N,N -Dimethylformamide (DMF) NAt least one of methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), and acetonitrile (ACN).

[0017] Furthermore, the water content is 5 wt% to 50 wt%, more preferably 10 wt% to 40 wt%.

[0018] Furthermore, the halogenated trifluoroethylene can be selected from one of trifluorochloroethylene, trifluorobromoethylene, or trifluoroiodoethylene.

[0019] Furthermore, the coupling agent is a borate ester or boric acid, including trimethyl borate (B(OMe)3), triethyl borate (B(OEt)3), and tri-n-propyl borate (B(O... n Pr)3), triisopropyl borate (B(O) i Pr)3), tributyl borate (B(O) n Bu)3), tritert-tert-butyl borate (B(O) t Bu)3), triisobutyl borate (B(O) i Bu)3), tri-n-pentyl borate (B(O) n Pen)3), triisoamyl borate (B(O) i Pen)3), Trihexyl borate (B(O) n Hex)3), triheptyl borate (B(O) n Hep)3), trioctyl borate (B(O) n Oct)3), isotrioctyl borate (B(O) i Oct)3), pinacol diboronate (B2pin2), pinacol borane (HBpin), isopropanol pinacol borate (i-PrBpin), bis(neopentylethylene glycol) diboron (B2neo2), bis(2-methyl-2,4-pentanediol) borate (B2hexyl2), bis(catechol) borate (B2cat2), tetrahydroxydiboron (BBA), tribenzyl borate (B(OBn)3), triphenyl borate (B(OPh)3), trichlorophenyl borate (B(OPhCl)3), and one of their respective carbon chain isomers.

[0020] Furthermore, the catalysts are palladium-based catalysts including palladium dichloride (PdCl2), tetra(triphenylphosphine)palladium (Pd(PPh3)4), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride (PdCl2(dppf)), bis(triphenylphosphine)palladium(II) chloride (PdCl2(PPh3)2), 1,3-bis(diphenylphosphine)propanepalladium(II) chloride (PdCl2(dppp)), tris(dibenzylideneacetone)dipalladium (Pd2(dba)3), [(2-dimethylamino)propyldiphenylphosphine]palladium(II) chloride (PdCl2(alaPhos)), dichloro[9,9-dimethyl-4,5-bis(diphenylphosphine)oxanthracene]palladium(II) (PdCl2(XantPhos)), palladium acetate (Pd(OAc)2), and palladium catalyst supported on activated carbon (Pd / C, Palladium on activated carbon). One of charcoal and palladium nitrate (Pd(NO3)2).

[0021] Furthermore, the catalyst coordinates with phosphine-based ligands to form an active catalyst.

[0022] Furthermore, the alkali includes potassium carbonate, sodium carbonate, cesium carbonate, potassium hydroxide, sodium hydroxide, potassium methoxide, sodium methoxide, sodium tert-butoxide, potassium tert-butoxide, lithium tert-butoxide, etc., preferably group 1A (alkali metal) cationic alkalis.

[0023] 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.

[0024] Furthermore, the molar ratio of the catalyst to halotrifluoroethylene is 0.01 to 10 mol%, preferably 1 to 5 mol%.

[0025] Furthermore, the molar ratio of phosphine ligand to catalyst is 0.1 to 5.0 mol%, preferably 0.5 to 3 mol%.

[0026] Furthermore, the molar ratio of the alkali to the halotrifluoroethylene is 0.5:1 to 3:1, preferably 1:1 to 2:1.

[0027] Furthermore, the reaction temperature is from room temperature to 300°C, preferably from 50°C to 200°C.

[0028] The beneficial effects of this invention are as follows: Compared with the prior art, this invention has significant advantages. 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 produce ODPs or high GWP byproducts, which conforms to the principles of green chemistry; the optimized catalytic system achieves highly selective conversion, and the product can be obtained with 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, which gives it outstanding potential for industrial application. Instruction manual illustrations

[0029] Figure 1 This is a diagram illustrating the one-step reaction mechanism of hexafluorobutadiene according to the present invention. Detailed Implementation

[0030] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following detailed description is provided in conjunction with specific embodiments.

[0031] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description is provided in conjunction with the specific embodiments listed. The embodiments described in this invention are merely illustrative of the technical solutions of this application and are therefore only examples, not intended to limit the scope of protection of this application.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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 between these entities or operations.

[0036] 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.

[0037] 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.

[0038] A method for synthesizing hexafluorobutadiene includes the following steps: in a reaction vessel, an organic solvent, a halotrifluoroethylene, a coupling reagent, a catalyst, and a base are added simultaneously, and the mixture is heated to carry out a coupling reaction. After the reaction is completed, the reaction solution is washed, extracted, dried, and distilled to obtain hexafluorobutadiene. The general reaction formula of the method is as follows.

[0039]

[0040] Where X is Cl (trifluorochloroethylene), Br (trifluorobromoethylene) or I (trifluoroiodoethylene); Y is BR (boronic acid ester or boric acid).

[0041] In some embodiments, the organic solvent comprises a polar solvent or a nonpolar solvent.

[0042] In some embodiments, the catalyst is coordinated with a phosphine-based ligand to form an active catalyst, wherein the ligand may be triphenylphosphine (PPh3), tri-tert-butylphosphine (P(t-Bu)3), tricyclohexylphosphine (PCy3), tri(o-methylphenyl)phosphine (P(o-Tol)3), trifuranylphosphine (P(2-Fur)3), tri(pentafluorophenyl)phosphine (P(C5F5)3), or tri(2,4,6-trimethoxyphenyl)phosphine (P(2,4,6-(OMe)3C) Phosphides such as 1,1-bis(diphenylphosphino)ferrocene (DPPF), 1,2-bis(diphenylphosphino)ethane (DPPE), 1,3-bis(diphenylphosphino)propane (DPPP), 1,4-bis(diphenylphosphino)butane (DPPB), 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene (Xantphos), and 1,1'-binaphthyl-2,2'-bisdiphenylphosphine (BINAP) can be coordinated with palladium catalysts.

[0043] like Figure 1 As shown, the reaction mechanism steps of this invention are as follows:

[0044] Step 1: First oxidative addition, Pd (0) Forms alkenyl-Pd with halotrifluoroethylene (II) –X intermediate.

[0045] Step 2: First metal ring replacement, ligand metal exchange between the base and the borate ester.

[0046] Step 3: The first elimination reaction involves phosphine ligands promoting the reductive elimination reaction, producing trifluoroethylene boron ester. This boron ester can further participate in the next cycle, while Pd... (II) Restore to Pd (0) Then, the next round of catalytic reaction continues.

[0047] Step 4: Second metal ring replacement. After repeating step 1, the base undergoes ligand metal exchange with trifluoroethylene boron ester.

[0048] Step 5: Second elimination reaction, phosphine ligands participate to promote reductive elimination, producing hexafluorobutadiene, while Pd... (II) Restore to Pd (0) This allows for the continuation of the next round of catalytic reaction.

[0049] 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.

[0050] Table 1 shows Examples 1-10.

[0051]

[0052] Example 1 160 g of dimethyl sulfoxide and 40 g of deionized water were added to the reactor, followed by pinacol diboron ester (40 g, 160 mmol, 1.60 eq), cesium carbonate (45.6 g, 140 mmol, 1.40 eq), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride (2.3 g, 2.5 mmol, 2.5 mol%), and Xantphos (1.3 g, 2 mmol, 2.0 mol%). Trifluoroiodide (20.8 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 150 °C for 7 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected and distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.94% and a yield of 85% based on trifluoroiodide.

[0053] Example 2 150 g of dimethylacetamide and 50 g of deionized water were added to the reactor, followed by tripentyl borane (B(OPn)3, 38.0 g, 140 mmol, 1.40 eq), potassium hydroxide (11.2 g, 200 mmol, 2.00 eq), bis(triphenylphosphine)palladium(II) chloride (2.1 g, 3 mmol, 3.0 mol%), and Xantphos (1.3 g, 2 mmol, 2.0 mol%). Trifluorobromoethylene (16.1 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 150 °C for 8 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 99.88% and a yield of 68% based on trifluorobromoethylene.

[0054] Example 3 140 g of acetonitrile and 40 g of deionized water were added to the reactor, followed by pinacol borane (17.3 g, 120 mmol, 1.20 eq), potassium hydroxide (5.6 g, 100 mmol, 1.00 eq), palladium acetate (0.4 g, 2 mmol, 2.0 mol%), and tricyclohexylphosphine (0.7 g, 2 mmol, 2.0 mol%). Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 90 °C for 12 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 99.89% and a yield of 79% based on trifluorochloroethylene.

[0055] Example 4 150 g of 1,4-dioxane and 50 g of deionized water were added to the reactor, followed by tri(chlorophenoxy)borane (B(OPhCl)3, 49.0 g, 140 mmol, 1.40 eq), sodium hydroxide (8.0 g, 200 mmol, 2.00 eq), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride (2.1 g, 3 mmol, 3.0 mol%), and BINAP (0.6 g, 1 mmol, 1.0 mol%). Trifluoroiodide (20.8 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 95 °C for 8 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 99.94% and a yield of 72% based on trifluoroiodide.

[0056] Example 5 160 g of N-methylpyrrolidone and 40 g of deionized water were added to the reactor, followed by pinacol diboron ester (32.5 g, 130 mmol, 1.30 eq), cesium carbonate (42.4 g, 130 mmol, 1.30 eq), palladium dichloride (0.2 g, 1 mmol, 1.0 mol%), and Xantphos (1.3 g, 2 mmol, 2.0 mol%). Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 200 °C for 8 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected. Hexafluorobutadiene, the target product, was obtained by distillation with a purity of 99.93% and a yield of 81% based on trifluorochloroethylene.

[0057] Example 6 160 g of dimethylformamide and 40 g of deionized water were added to the reactor, followed by tribenzyloxyborane (B(OBn)3, 51.0 g, 150 mmol, 1.50 eq), potassium carbonate (20.7 g, 150 mmol, 1.50 eq), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride (2.1 g, 3 mmol, 3.0 mol%), and triphenylphosphine (0.8 g, 3 mmol, 3.0 mol%). Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 140 °C for 10 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 99.90% and a yield of 70% based on trifluorochloroethylene.

[0058] Example 7 165 g of dimethylformamide and 35 g of deionized water were added to the reactor, followed by pinacol diboron ester (20.0 g, 80 mmol, 0.80 eq), potassium carbonate (15.2 g, 110 mmol, 1.10 eq), tetrakis(triphenylphosphine)palladium (1.2 g, 1 mmol, 1.0 mol%), and tricyclohexylphosphine (0.7 g, 2 mmol, 2.0 mol%). Trifluoroiodide (20.8 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 140 °C for 6 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 99.90% and a yield of 65% based on trifluoroiodide.

[0059] Example 8 140 g of acetonitrile and 60 g of deionized water were added to the reactor, followed by bis(2-methyl-2,4-pentanediol)borate (B2hexyl2, 45 g, 150 mmol, 1.50 eq), potassium hydroxide (11.2 g, 200 mmol, 2.00 eq), palladium acetate (1.1 g, 5 mmol, 5.0 mol%), and DPPP (0.5 g, 1.5 mmol, 1.5 mol%). Trifluorobromoethylene (16.1 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 90 °C for 9 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 99.90% and a yield of 82% based on trifluorobromoethylene.

[0060] Example 9 150 g of dimethyl sulfoxide and 50 g of deionized water were added to the reactor, followed by trimethoxyborane (B(OMe)3, 20.7 g, 200 mmol, 2.00 eq), cesium carbonate (26.2 g, 80 mmol, 0.80 eq), tris(dibenzylacetone)dipalladium (4.6 g, 5 mmol, 5.0 mol%), and Xantphos (1.3 g, 2 mmol, 2.0 mol%). Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 180 °C for 7 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 99.92% and a yield of 66% based on trifluorochloroethylene.

[0061] Example 10 Add 140 g of toluene and 60 g of deionized water to the reactor, followed by the addition of tri-tert-butoxyborane (B(O)). t The reaction mixture consisted of 21.0 g (70 mmol, 0.70 eq) of Bu3, 20.7 g (150 mmol, 1.50 eq) of potassium carbonate, 20.7 g (150 mmol, 1.50 eq) of potassium carbonate, 2.1 g (3 mmol, 3.0 mol%) of [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride, and 0.5 g (1.5 mmol, 1.5 mol%) of DPPP. Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 90 °C for 8 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected and distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.95% and a yield of 60% based on trifluorochloroethylene.

[0062] Table 2 shows Examples 11-20.

[0063]

[0064] Example 11 150 g of N,N-dimethylacetamide and 50 g of deionized water were added to the reactor, followed by bis(neopentylethylene glycol)diboron (B₂neo₂, 36.0 g, 120 mmol, 1.20 eq), cesium carbonate (39.1 g, 120 mmol, 1.20 eq), tris(dibenzylacetone)dipalladium (2.7 g, 3 mmol, 3.0 mol%), and Xantphos (1.3 g, 2 mmol, 2.0 mol%). Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 105 °C for 10 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 99.92% and a yield of 79% based on trifluorochloroethylene.

[0065] Example 12 160 g of dimethyl sulfoxide and 40 g of deionized water were added to the reactor, followed by tetrahydroxydiboron (BBA, 21.8 g, 140 mmol, 1.40 eq), potassium hydroxide (8.4 g, 150 mmol, 1.50 eq), palladium dichloride (0.7 g, 3 mmol, 3.0 mol%), and PCy3 (0.7 g, 2 mmol, 2.0 mol%). Trifluoroiodide (20.8 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 120 °C for 7 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 99.91% and a yield of 83% based on trifluoroiodide.

[0066] Example 13 150 g of dimethylacetamide and 40 g of water were added to the reactor, followed by bis(diphenylphosphine)boronic acid ester (B2cat2, 31.4 g, 110 mmol, 1.10 eq), potassium carbonate (15.2 g, 110 mmol, 1.10 eq), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride (2.3 g, 2.5 mmol, 2.5 mol%), and BINAP (0.6 g, 1 mmol, 1.0 mol%). Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was then introduced under stirring, and the reaction was maintained at 160 °C for 8 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 99.94% and a yield of 76% based on trifluorochloroethylene.

[0067] Example 14 Add 120 g of methanol and 60 g of deionized water to the reactor, followed by the addition of trioctyl oxyborane (B(O)). n On October 3, 63.0 g (130 mmol, 1.30 eq), potassium carbonate (20.7 g, 150 mmol, 1.50 eq), tetra(triphenylphosphine)palladium (1.2 g, 1 mmol, 1.0 mol%), and tricyclohexylphosphine (0.7 g, 2 mmol, 2.0 mol%) were added. Trifluorobromoethylene (16.1 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 75 °C for 12 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected and distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.89% and a yield of 64% based on trifluorobromoethylene.

[0068] Example 15 160 g of N,N-dimethylformamide and 40 g of deionized water were added to the reactor, followed by pinacol diboron ester (30 g, 120 mmol, 1.20 eq), potassium carbonate (18 g, 130 mmol, 1.30 eq), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) chloride (2.8 g, 3 mmol, 3.0 mol%), and triphenylphosphine (0.8 g, 3 mmol, 3.0 mol%). Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 150 °C for 10 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected. Hexafluorobutadiene, the target product, was obtained by distillation with a purity of 99.95% and a yield of 78% based on trifluorochloroethylene.

[0069] Example 16 150 g of diethylene glycol dimethyl ether and 60 g of deionized water were added to the reactor, followed by pinacol borane (25.9 g, 180 mmol, 1.80 eq), sodium hydroxide (8.0 g, 200 mmol, 2.00 eq), palladium acetate (1.1 g, 5 mmol, 5.0 mol%), and tri-o-methylphenylphosphine (0.6 g, 2 mmol, 2.0 mol%). Trifluorobromoethylene (16.1 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 140 °C for 9 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 99.92% and a yield of 83% based on trifluorobromoethylene.

[0070] Example 17 Toluene (150 g) and deionized water (50 g) were added to the reactor, followed by bis(neopentylethylene glycol)diboron (B₂neo₂, 21.8 g, 75 mmol, 0.75 eq), potassium carbonate (15.2 g, 110 mmol, 1.10 eq), tetra(triphenylphosphine)palladium (1.2 g, 1 mmol, 1.0 mol%), and P(o-Tol)₃ (0.6 g, 2 mmol, 2.0 mol%). Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced with stirring, and the reaction was maintained at 125 °C for 8 hours. After the reaction was complete, 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 99.89% and a yield of 61% based on trifluorochloroethylene.

[0071] Example 18 150 g of dimethylacetamide and 50 g of deionized water were added to the reactor, followed by pinacol diboron ester (32.5 g, 130 mmol, 1.30 eq), potassium carbonate (13.8 g, 100 mmol, 1.00 eq), palladium acetate (0.7 g, 3 mmol, 3.0 mol%), and triphenylphosphine (0.5 g, 2 mmol, 2.0 mol%). Trifluorobromoethylene (16.1 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 145 °C for 8 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 99.92% and a yield of 80% based on trifluorobromoethylene.

[0072] Example 19 Add 160 g of N,N-dimethylformamide and 40 g of deionized water to the reactor, followed by the addition of triisopropoxyborane (B(O)). i The reaction mixture consisted of Pr3 (37.5 g, 150 mmol, 1.50 eq), potassium hydroxide (11.2 g, 200 mmol, 2.00 eq), palladium acetate (1.1 g, 5 mmol, 5.0 mol%), and Xantphos (1.3 g, 2 mmol, 2.0 mol%). Trifluorobromoethylene (16.1 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 140 °C for 9 hours. After the reaction was complete, the system was cooled, and after routine washing and separation, the organic layer was collected and distilled to obtain the target product, hexafluorobutadiene, with a purity of 99.91% and a yield of 69% based on trifluorobromoethylene.

[0073] Example 20 Add 120 g of methanol and 60 g of deionized water to the reactor, followed by the addition of isopropanol pinacol borate ester (…). i PrBpin (16 g, 80 mmol, 0.80 eq), potassium hydroxide (11.2 g, 200 mmol, 2.00 eq), tetra(triphenylphosphine)palladium (1.2 g, 1 mmol, 1.0 mol%), and tricyclohexylphosphine (0.7 g, 2 mmol, 2.0 mol%) were added. Trifluorochloroethylene (11.6 g, 100 mmol, 1.00 eq) was introduced under stirring, and the reaction was maintained at 70 °C for 16 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 99.88% and a yield of 60% based on trifluorochloroethylene.

[0074] In summary, the hexafluorobutadiene synthesis method provided by this invention, through specific catalytic system and reaction parameter design, exhibits high reaction efficiency and high selectivity across different types of coupling reagents and a wide reaction temperature range. Experimental data show that the hexafluorobutadiene yield synthesized by this method is ≥60%, with a purity ≥99.8%. Furthermore, this method effectively overcomes the technical shortcomings of existing technologies, such as lengthy routes, use of high-risk (e.g., magnesium, zinc, hydrides), highly toxic reagents (e.g., mercury), and harsh reaction conditions (e.g., high temperatures), resulting in numerous byproducts, difficult product purification, and low yields. Therefore, it demonstrates significant advantages in product purity, process safety, and production cost, possessing outstanding industrial application value.

[0075] 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 hexafluorobutadiene, characterized in that, The process includes the following steps: In a reaction vessel, an organic solvent, water, halotrifluoroethylene, coupling reagent, catalyst, and base are added simultaneously, and the mixture is heated to carry out a coupling reaction. After the reaction is completed, the reaction solution is washed, extracted, dried, and distilled to obtain hexafluorobutadiene.

2. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The organic solvents include toluene, dichloromethane, 1,2-dichloroethane, carbon tetrachloride, tetrahydrofuran (THF), diethylene glycol dimethyl ether, and 1,4-dioxane. N,N -Dimethylformamide (DMF) N At least one of methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), and acetonitrile (ACN).

3. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The water content is 5 wt% to 50 wt%, more preferably 10 wt% to 40 wt%.

4. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The halogenated trifluoroethylene may be selected from one of trifluorochloroethylene, trifluorobromoethylene, or trifluoroiodoethylene.

5. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The coupling reagent is a borate ester or boric acid.

6. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The catalyst is a palladium-based catalyst.

7. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The catalyst coordinates with a phosphine-based ligand to form an active catalyst.

8. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The alkali includes potassium carbonate, sodium carbonate, cesium carbonate, potassium hydroxide, sodium hydroxide, potassium methoxide, sodium methoxide, sodium tert-butoxide, potassium tert-butoxide, lithium tert-butoxide, etc., preferably a group 1A (alkali metal) cationic alkali.

9. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The molar ratio of the coupling agent to the halotrifluoroethylene is 0.5:1 to 3:1, preferably 0.6:1 to 2:

1.

10. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The molar ratio of the catalyst to halotrifluoroethylene is 0.01 to 10 mol, preferably 1 to 5 mol.

11. The method for synthesizing hexafluorobutadiene according to claim 7, characterized in that, The molar ratio of the phosphine ligand to the catalyst is 0.1 to 5.0 mol, preferably 0.5 to 3 mol.

12. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The molar ratio of the alkali to the halotrifluoroethylene is 0.5:1 to 3:1, preferably 1:1 to 2:

1.

13. The method for synthesizing hexafluorobutadiene according to claim 1, characterized in that, The reaction temperature is from room temperature to 300°C, preferably from 50°C to 200°C.

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