High-purity hexafluorobutadiene and preparation method thereof

Abstract

The invention discloses high-purity hexafluorobutadiene and a preparation method thereof. The preparation method comprises the following steps: S1, preparation of a halogenated trifluoroethylene Grignard reagent; S2, coupling reaction of an organic solvent, a catalyst, halogenated trifluoroethylene and the halogenated trifluoroethylene Grignard reagent; s3, treating and rectifying a hexafluorobutadiene product to obtain high-purity hexafluorobutadiene; compared with the prior art, the preparation method has the advantages that the steps are simplified, continuous production can be realized, the preparation method is suitable for large-scale industrialization, and the hexafluorobutadiene obtained by the preparation method has high purity and high yield.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of hexafluorobutadiene and its preparation method, especially to a kind of high purity hexafluorobutadiene and its preparation method. BACKGROUND

[0002] Hexafluorobutadiene is an important fluorine-containing special gas, hexafluorobutadiene is a new type of fluorine-containing green electronic etching gas, with the advantages of fast etching rate, high aspect ratio, high selectivity, can realize nearly vertical etching processing, provide the possibility for manufacturing small volume, large capacity 3D NAND flash;At the same time, hexafluorobutadiene is environmentally friendly, greenhouse effect potential (GWP value) is only 290, atmospheric lifetime is 1.9 days, it is the only fluorine-containing electronic etching gas with excellent etching performance and environmental performance at present. At the same time, hexafluorobutadiene can be used as a monomer to synthesize new fluororesin, fluorine rubber, etc., has broad market application prospect.

[0003] At present, many researchers have carried out relevant research on the preparation method of hexafluorobutadiene. The main process includes:

[0004] For example, US3046304 discloses a process route for synthesizing hexafluorobutadiene from trifluorochloroethylene. This process avoids the high temperature and high pressure conditions of the telomerization reaction, but mercury is needed to participate in the reaction, and the other product is mercury iodide, which is highly toxic.

[0005] For example, Burton group (Tetrahedron Lett.43(2002)2731-2733), Beijing Yujie Science and Technology Development Co., Ltd. patent CN104844411A discloses a method for preparing hexafluorobutadiene from HFC-134a as raw material. Due to the high GWP value of HFC-134a, its use is controlled.

[0006] For example, Zhonghua Blue Sky Group Co., Ltd. patent CN116120146B discloses a production method using trifluorochloroethylene as raw material, including: (1) trifluorochloroethylene is reduced to trifluoroethylene by metal catalytic hydrogenation; (2) trifluoroethylene reacts with bromine under light to obtain 1,2-dibromotri-fluoroethane; (3) 1,2-dibromotri-fluoroethane reacts with solid base to obtain trifluorobromoethylene; (4) trifluorobromoethylene is mixed with zinc powder and initiator to react to obtain trifluorovinyl zinc bromide; (5) trifluorovinyl zinc bromide is coupled under the action of coupling catalyst to synthesize hexafluorobutadiene. This method has many synthesis steps, and after obtaining high-activity zinc reagent, the zinc reagent is self-coupled under the action of excess metal coupling catalyst to prepare hexafluorobutadiene. Two molecules of zinc reagent are needed to generate one molecule of hexafluorobutadiene in the self-coupling process, which causes the disadvantage of low unit volume yield. At the same time, excessive coupling catalyst needs to be added in the production process, which increases the cost of raw materials and the cost of solid waste treatment.

[0007] For example, Guangdong Huate Gas Co., Ltd. CN116283481A discloses a method for preparing hexafluorobutadiene by using chlorotrifluoroethylene as raw material, high-temperature dimerization, and zinc dechlorination. South Day Optoelectronics patent CN116422236A and Sanai Fu New Material Co., Ltd. patent CN104496748A respectively disclose a method for preparing 3,4-dichlorohexafluoro-1-butene by using chlorotrifluoroethylene as raw material, high-temperature cracking, and then synthesizing hexafluorobutadiene. Although this method has fewer reaction steps, the reaction temperature is high, impurities are generated, it is difficult to purify, and the yield is low.

[0008] For example, China University of Mining and Technology CN111087281A discloses a method for preparing hexafluorobutadiene by using octafluorocyclobutene as raw material, high-temperature reaction of 250-800°C under the action of isomerization catalyst. Although this reaction can be prepared in one step, the preparation of the catalyst before the reaction is complex, the raw material octafluorocyclobutene is difficult to obtain, and the price is high. The purity and yield of the reaction product are low.

[0009] The above-mentioned prior art has the problems of complicated preparation steps, low product purity and low yield, which seriously affect the production scale of hexafluorobutadiene and the application prospect of the downstream. SUMMARY

[0010] Therefore, in order to overcome the above-mentioned problems, the present application provides a high-purity hexafluorobutadiene and a preparation method thereof. The preparation method has simplified steps, is suitable for large-scale industrialization, and the hexafluorobutadiene obtained by the preparation method has the characteristics of high purity and high yield. The technical scheme is as follows:

[0011] A preparation method of high-purity hexafluorobutadiene, comprising the following steps:

[0012] S1: In an inert gas reaction container, add magnesium chips and anhydrous organic solvent, and drop a mixed solution of halogenated trifluoroethylene and tetrahydrofuran under stirring conditions. After the dropping is completed, continue to stir and react to obtain a halogenated trifluoroethylene Grignard reagent.

[0013] S2: Under the protection of inert gas, add an organic solvent, a catalyst and halogenated trifluoroethylene to another reaction bottle. Then, drop the halogenated trifluoroethylene Grignard reagent solution prepared in S1. After the dropping is completed, continue to stir and react to make the coupling reaction proceed fully, and generate hexafluorobutadiene.

[0014] Further, the preparation method further comprises a step S3, which is adding dilute acid to the reaction system after the reaction in the step S2 is completed to perform hydrolysis. After hydrolysis, the reaction mixture is transferred to a separatory funnel to perform liquid separation operation, and the organic phase is separated out. The organic phase is treated by a drying agent, and then purified by rectification.

[0015] Further, the preparation method of the hexafluorobutadiene is characterized in that the inert gas is nitrogen or argon.

[0016] Further, the halogenated trifluoroethylene can be any one of trifluoro-chloroethylene, trifluoro-bromoethylene, and trifluoro-iodoethylene.

[0017] Further, the organic solvent includes any one of tetrahydrofuran, diethylene glycol dimethyl ether, 1,4-dioxane, methyl tert-butyl ether, and acetonitrile.

[0018] Further, the mass ratio of the magnesium chips to the organic solvent is (0.5-2):10; the mass ratio of the halogenated trifluoroethylene to the organic solvent is 1:5-10; and the molar ratio of the halogenated trifluoroethylene to the magnesium chips is (1-1.2):(1-2).

[0019] Further, the catalyst is a nickel-based catalyst and / or a palladium-based catalyst, and the nickel-based catalyst is further preferred, including nickel chloride NiCl2(dppe), NiCl2(dppf), NiCl2(pph3)2, and NiCl2(bpy), and the palladium-based catalyst includes PdCl2(dppf) and Pd(PPh3)4.

[0020] Further, the ratio of the halogenated trifluoroethylene to the halogenated trifluoroethylene Grignard reagent is (0.7-1):(1-2).

[0021] Further, the molar ratio of the nickel-based catalyst to the halogenated trifluoroethylene Grignard reagent is (1%-20%):1.

[0022] Further, the molar ratio of the palladium-based catalyst to the halogenated trifluoroethylene Grignard reagent is (0.1%-3%):(1-3).

[0023] Further, the drying agent is any one of anhydrous magnesium sulfate and anhydrous sodium sulfate.

[0024] Further, the reaction time after the dropwise addition in S1 is 1-24 hours.

[0025] Further, the coupling reaction temperature in S2 is 0-70°C, and the reaction time is 1-24 hours.

[0026] Further, the purity of the hexafluorobutadiene obtained by the preparation method is ≥99.9% after rectification.

[0027] The beneficial effects of the present application: through the preparation method of the present application: S1 preparation of halogenated trifluorovinyl Grignard reagent, S2 coupling reaction of organic solvent, catalyst, halogenated trifluorovinyl and halogenated trifluorovinyl Grignard reagent; S3 hexafluorobutadiene product treatment and rectification, high-purity hexafluorobutadiene is obtained; compared with the prior art, the preparation method of the present application simplifies the steps, can realize continuous production, is suitable for large-scale industrialization, and the hexafluorobutadiene obtained by the preparation method has high purity and high yield. DETAILED DESCRIPTION

[0028] In order to explain the technical content, structural features, purposes and effects of the technical scheme in detail, the following will be described in detail in combination with specific embodiments.

[0029] In order to explain the possible application scenarios, technical principles, specific schemes that can be implemented, purposes and effects of the present application, the following will be described in detail in combination with the specific embodiments listed. The embodiments described in the present application are only used to more clearly illustrate the technical scheme of the present application, therefore only as an example, and cannot limit the protection scope of the present application.

[0030] In the present application, the term "embodiment" means that the specific features, structures or characteristics described in combination with the embodiment can be included in at least one embodiment of the present application. The term "embodiment" appearing at various positions in the specification does not necessarily refer to the same embodiment, and does not particularly limit the independence or association between other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, each technical feature mentioned in each embodiment can be combined in any way to form a corresponding implementable technical scheme.

[0031] Unless otherwise defined, the meanings of the technical terms used in the present application are the same as those commonly understood by the person skilled in the art to which the present application belongs; the use of related terms in the present application is only for the purpose of describing specific embodiments, and is not intended to limit the present application.

[0032] In the description of the present application, the phrase "and / or" is a description of the logical relationship between the objects, which means that there are three relationships, for example, A and / or B, which means that there are three cases: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in the present application generally represents that the associated objects before and after are a "or" logical relationship.

[0033] In the present application, such as "first" and "second", the phrases are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, primary and secondary or order relationship between the entities or operations.

[0034] In the present application, the terms "comprise", "contain", "include", or other similar forms are intended to cover non-exclusive inclusions, and do not exclude additional elements from the process, method or product comprising the elements, so that the process, method or product comprising a series of elements can not only include those defined elements, but also include other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0035] In the present application, the terms "greater than", "less than", "exceed" and the like are understood as not including the number; the terms "above", "below", "within" and the like are understood as including the number. In addition, in the description of the embodiments of the present application, the meaning of "multiple" is two or more (including two), and similar expressions related to "multiple" are also understood in this way, for example, "multiple groups", "multiple times" and the like, unless otherwise explicitly specified.

[0036] S1: Preparation of halogenated trifluoroethylene Grignard reagent, in a dry and inert gas filled reaction vessel, add appropriate amount of magnesium chips and anhydrous organic solvent, then slowly drop the mixture of halogenated trifluoroethylene and tetrahydrofuran under stirring, strictly control the reaction temperature during the dropping process, after the dropping is completed, continue to stir the reaction, so that the reaction is carried out sufficiently, thereby preparing the halogenated trifluoroethylene Grignard reagent for standby.

[0037]

[0038] The halogenated trifluoroethylene can be any one of trifluorochloroethylene, trifluorobromoethylene, trifluoroiodoethylene.

[0039] The organic solvent includes any one of tetrahydrofuran, diethylene glycol dimethyl ether, 1,4-dioxane, methyl tert-butyl ether, acetonitrile and the like. If the ratio of the organic solvent to the magnesium chips is too low, the reaction sites are dense, local intense heat release and poor heat dissipation are prone to occur, and violent boiling and material flushing are prone to be caused; if the ratio of the organic solvent to the magnesium chips is too low, the reaction is not easy to be initiated, the number of active reaction sites is small, and the reaction rate is significantly slowed down, thus the reaction time is prolonged, therefore, in the embodiments of the present application, the mass ratio of the magnesium chips to the organic solvent is controlled to be between 0.5-2:10.

[0040] It is found by the present application that in the mass ratio relationship between the halogenated trifluoroethylene and the organic solvent, if the proportion of the organic solvent is too high, the polymerization reaction rate is significantly reduced, the reaction time is greatly prolonged, the production efficiency is low, and it is difficult to achieve the required conversion rate; on the contrary, if the proportion of the organic solvent is too low, stirring is difficult, the mass and heat transfer efficiency is sharply reduced, and the risk of local overheating and uneven reaction is intensified. Therefore, in the present application, the mass ratio of the halogenated trifluoroethylene to the organic solvent is controlled to be between 1:5-10, and more preferably the ratio is 1:10.

[0041] The application research found that the molar ratio of halogenated trifluoroethylene to magnesium chips is controlled between (1-1.2):(1-2), which can effectively avoid the excess of halogenated hydrocarbon, so as to prevent the incomplete reaction of halogenated hydrocarbon from affecting the yield; and too much excess of magnesium chips will increase the operation cost and is not conducive to the post-treatment (acid washing is needed to remove a large amount of unreacted magnesium).

[0042] In the embodiment of the application, the dropping process and the reaction temperature are 0-70℃, and the reaction temperature is further preferably 40-60℃.

[0043] In the embodiment of the application, the reaction time after the dropping is completed is 1-24 hours, and the reaction time is further preferably 4-7h.

[0044] Table 1: Experimental data of different halogenated trifluoroethylenes as raw materials are as follows.

[0045]

[0046] According to Table 1, it can be seen that the halogenated trifluoroethylene Grignard reagent with a purity of ≥90% can be obtained by strictly adjusting the reaction according to the above limited proportion relationship when different halogenated trifluoroethylenes are used as raw materials, and the reaction temperature and reaction time of the trifluoroiodoethylene group are relatively low, but the purity of the reagent of this group is 97%.

[0047] S2: Under the protection of inert gas, an organic solvent, a catalyst and halogenated trifluoroethylene are added into another reaction bottle, then the halogenated trifluoroethylene Grignard reagent solution prepared in S1 is dropped at 30-50℃, after the dropping is completed, the stirring and heat preservation reaction is continued, so that the coupling reaction is fully carried out, and hexafluorobutadiene is generated.

[0048]

[0049] The organic solvent includes tetrahydrofuran, diethylene glycol dimethyl ether, 1,4-dioxane, methyl tert-butyl ether, acetonitrile and the like, and further, the organic solvent in the embodiment of the application is preferably tetrahydrofuran.

[0050] The catalyst in the application is a nickel-based catalyst and / or a palladium-based catalyst, wherein the nickel-based catalyst includes nickel chloride NiCl2(dppe), NiCl2(dppf), NiCl2(pph3)2, NiCl2(bpy); and the palladium-based catalyst includes PdCl2(dppf), Pd(PPh3)4.

[0051] The ratio of halogenated trifluoroethylene to halogenated trifluoroethylene Grignard reagent is (0.7-1):(1-3), and too low ratio of halogenated trifluoroethylene leads to incomplete reaction; slightly excess of halogenated trifluoroethylene Grignard reagent can promote the balance to move to the product direction, so as to ensure the full reaction of halogenated hydrocarbon, but it is not necessary to be too much, so as to avoid waste of raw materials.

[0052] The molar ratio of the nickel catalyst to the halogenated trifluoroethylene Grignard reagent is (1%-20%):1, and the molar ratio is further preferably (3%-15%):1, and the molar ratio is further preferably (8%-11%):1 in some embodiments; the proportion of the nickel catalyst is too low, which leads to low substrate conversion rate and prolonged reaction time; and the proportion of the nickel catalyst is too high, which directly leads to cost increase and more impurities in the reaction process.

[0053] The molar ratio of the palladium catalyst to the halogenated trifluoroethylene Grignard reagent is (0.1%-3%):(1-3), and the proportion of the palladium catalyst is too low, which leads to insufficient catalytic cycle times and reduced conversion rate; the reaction time is prolonged, and the proportion of the palladium catalyst is too high, which leads to cost increase and more impurities in the reaction process.

[0054] In the embodiments of the present application, the reaction temperature of S2 is 0-70℃, and the reaction temperature is further preferably 50-70℃ in combination with the embodiments; the present application research and development personnel know through long-term experiments that the reaction temperature exceeding 70℃ is the main risk point leading to the generation of dimers, and therefore further controlling the reaction temperature at 50-70℃ has a positive effect on reducing impurities.

[0055] In the embodiments of the present application, the reaction time is 1-24 hours, and the reaction time is further preferably 7-13h in combination with the embodiments.

[0056] S3: After the reaction of S2 is completed, dilute acid is added to the reaction system for hydrolysis, and after hydrolysis, the reaction mixture is transferred to a separatory funnel for separation operation, and the organic phase is separated out; the organic phase is treated by a drying agent, and then purified by rectification; the drying agent used in the embodiments of the present application is any one of anhydrous magnesium sulfate or anhydrous sodium sulfate.

[0057] Table 2 (Example 1): Trifluorochloroethylene is used as a raw material, and a nickel catalyst is used as a catalyst; the Grignard reagent prepared in S1 is added dropwise into the reaction system, and after the reaction is completed, the product is treated according to S3, and the data obtained by secondary pressurized rectification are as follows:

[0058]

[0059] Table 3 (Example 2): Trifluorochloroethylene is used as a raw material, and a palladium catalyst is used as a catalyst; the Grignard reagent prepared in S1 is added dropwise into the reaction system, and after the reaction is completed, the product is treated according to S3, and the data obtained by secondary pressurized rectification are as follows:

[0060]

[0061] Table 4 (Example 3): Using trifluorobromoethylene as raw material, the catalyst is a nickel catalyst, the Grignard reagent prepared in S1 is added to the reaction system, after the reaction is finished, the product is treated according to S3, and the data obtained by secondary pressurized rectification are as follows:

[0062]

[0063] Table 5 (Example 4): Using trifluorobromoethylene as raw material, the catalyst is a palladium catalyst, the Grignard reagent prepared in S1 is added to the reaction system, after the reaction is finished, the product is treated according to S3, and the data obtained by secondary pressurized rectification are as follows:

[0064]

[0065] Table 6 (Example 5): Using trifluoroiodoethylene as raw material, the catalyst is a nickel catalyst, the Grignard reagent prepared in S1 is added to the reaction system, after the reaction is finished, the product is treated according to S3, and the data obtained by secondary pressurized rectification are as follows:

[0066]

[0067] Table 7 (Example 6): Using trifluoroiodoethylene as raw material, the catalyst is a palladium catalyst, the Grignard reagent prepared in S1 is added to the reaction system, after the reaction is finished, the product is treated according to S3, and the data obtained by secondary pressurized rectification are as follows:

[0068]

[0069] According to the experimental results, examples 1-6 all have good hexafluorobutadiene yield, the prepared samples in the present application have a hexafluorobutadiene reaction purity of ≥80% under the conditions of each example, the yield after pressurized rectification can be stabilized at ≥70%, and the purity is all ≥99.9%, which overcomes the influence of catalysts, high-temperature preparation and other factors in the prior art on the generation of many impurities, difficult purification and low yield of hexafluorobutadiene.

[0070] Comparative Example 1

[0071] Using trifluorochloroethylene as raw material, the purified dimer is added to zinc powder to generate hexafluorobutadiene by dechlorination, and the specific steps are as follows:

[0072] (1) Preparation of polar base liquid: 100 kg of isopropyl alcohol and 100 kg of acetonitrile are put into a reaction kettle and mixed for 8 h to prepare a polar base liquid.

[0073] (2) Preparation of activated zinc: zinc particles with an average particle size of 4 mm were soaked in a 12% by mass aqueous HCl solution for 4.5 h, then washed with distilled water until the pH was 7, and then vacuum dried at a temperature of 200°C and a pressure of 1.5 kPa for 10 h to obtain activated zinc.

[0074] (3) Preparation of 1,2-dichloro-2-iodo-1,1,2-trifluoroethane: 100 kg of iodine was placed in a reactor, the temperature was set to 35°C, chlorine gas was introduced, and the molar ratio of iodine to chlorine gas was 1:0.8. The resulting liquid was distilled to obtain iodine monochloride; iodine monochloride 100 kg and trifluorochloroethylene were mixed and placed in a reactor, the molar ratio of iodine monochloride to trifluorochloroethylene was 1:1.1, polar base liquid 750 kg prepared in step (1) was added, the reaction temperature was -5°C, and the reaction time was 8 h. After further distillation, 1,2-dichloro-2-iodo-1,1,2-trifluoroethane was obtained.

[0075] (4) Preparation of 1,2,3,4-tetrachlorohexafluorobutane: 1,2-dichloro-2-iodo-1,1,2-trifluoroethane 100 kg prepared in step (3) and activated zinc prepared in step (2) were placed in a reactor, the molar ratio of 1,2-dichloro-2-iodo-1,1,2-trifluoroethane to activated zinc was 1:1.2, polar base liquid 800 kg prepared in step (1) and ethyl acetate 10 kg were added, and the reaction was carried out at a reaction temperature of 20°C for 7 h. After washing, drying, and distillation, 1,2,3,4-tetrachlorohexafluorobutane was obtained.

[0076] (5) Preparation of hexafluorobutadiene: 1,2,3,4-tetrachlorohexafluorobutane 100 kg prepared in step (4) and activated zinc prepared in step (2) were added to a reaction vessel, the molar ratio of 1,2,3,4-tetrachlorohexafluorobutane to activated zinc was 1:1.8, polar base liquid 650 kg prepared in step (1) and carbon tetrachloride 650 kg were added, and the reaction was carried out at a reaction temperature of 80°C for 3 h. After extraction, adsorption, and distillation, hexafluorobutadiene was obtained.

[0077]

[0078] This method is prepared by 4 steps, and the researchers further process the product, and the purity of the hexafluorobutadiene product obtained by secondary pressurized distillation is 99.3%, and the yield of this process is 42%.

[0079] Comparative Example 2

[0080] The 3,4-dichlorohexafluoro-1-butene is generated by pyrolysis of chlorotrifluoroethylene at 500℃, and the yield of this step is about 29% after purification. The purified dimer is then added to zinc powder to remove chlorine and generate hexafluorobutadiene, as follows.

[0081] (1) The chlorotrifluoroethylene is added to a preheater, and the preheater temperature is 160℃. The chlorotrifluoroethylene is added to a reactor, and the reactor temperature is 500℃. The material is pyrolyzed in the reactor, and the contact time is 50s. After the reaction is completed, the material is cooled. The gas is recovered by a compressor, and the collected liquid product is separated by rectification. The liquid is condensed by heat exchange with a condensing medium, and the liquid is introduced into a storage tank. The cyclic product in the storage tank is recycled to the reactor at 20%, and the different components of the liquid are collected. The straight-chain product is 3,4-dichlorohexafluoro-1-butene, which is an intermediate for preparing hexafluorobutadiene. After two rectifications, the yield of 3,4-dichlorohexafluoro-1-butene is 29%.

[0082] (2) The anhydrous ethanol and zinc powder are sequentially added to the reactor, and the purified 3,4-dichlorohexafluoro-1-butene is slowly added to the reactor. The reaction temperature is controlled at 38-45℃, and the reaction time is 24h. After pressurized rectification, the purity of the product is 98.9%, and the total yield of the two steps is 27%.

[0083]

[0084] The product is further treated by the researchers, and the purity of the hexafluorobutadiene product obtained by secondary pressurized rectification is 98.9%. The yield of the process is 27%.

[0085] The above description of the disclosed embodiments enables one skilled in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended 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 producing high purity hexafluorobutadiene, characterized by, The preparation method comprises the following steps: S1: adding magnesium turnings and anhydrous organic solvent into a reaction vessel under inert gas, and adding dropwise a mixed solution of halogenated trifluoroethylene and tetrahydrofuran under stirring, and continuing to stir and react after the dropwise addition is completed to obtain a halogenated trifluoroethylene Grignard reagent; S2: adding an organic solvent and a catalyst into another reaction vessel under inert gas protection, and then adding dropwise the halogenated trifluoroethylene Grignard reagent solution prepared in S1, and continuing to stir and react after the dropwise addition is completed to make the coupling reaction fully proceed to generate hexafluorobutadiene.

2. The method for producing hexafluorobutadiene according to claim 1, characterized by, The preparation method further comprises a step S3 of adding dilute acid to the reaction system for hydrolysis after the reaction in the step S2 is completed, transferring the reaction mixture to a separatory funnel after the hydrolysis, performing a liquid separation operation to separate the organic phase, and performing purification through rectification after the organic phase is treated by a drying agent.

3. The method for preparing hexafluorobutadiene according to claim 1, characterized in that, The inert gas is nitrogen or argon.

4. The method of claim 1, wherein The halogenated trifluoroethylene can be any one of trifluorochloroethylene, trifluorobromoethylene or trifluoroiodoethylene.

5. The method for preparing hexafluorobutadiene according to claim 1, characterized in that, The organic solvent comprises any one of tetrahydrofuran, diethylene glycol dimethyl ether, 1,4-dioxane, methyl tert-butyl ether or acetonitrile.

6. The method for preparing hexafluorobutadiene according to claim 1, characterized in that, The mass ratio of the magnesium turnings to the organic solvent is (0.5-2):10, the mass ratio of the halogenated trifluoroethylene to the organic solvent is 1:5-10, and the molar ratio of the halogenated trifluoroethylene to the magnesium turnings is (1-1.2):(1-3).

7. The method for preparing hexafluorobutadiene according to claim 1, characterized in that, The catalyst is a nickel-based catalyst and / or a palladium-based catalyst.

8. The method for preparing hexafluorobutadiene according to claim 1, characterized in that, The ratio of the halogenated trifluoroethylene to the halogenated trifluoroethylene Grignard reagent is (0.7-1):(1-3).

9. The method for preparing hexafluorobutadiene according to claim 2, characterized in that, The drying agent is anhydrous magnesium sulfate or anhydrous sodium sulfate.

10. Hexafluorobutadiene obtainable by the production process according to any one of claims 1 to 9, characterized in that The purity of the hexafluorobutadiene after rectification is greater than or equal to 99.9%.

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