WO2021254372A1

WO2021254372A1 - Method for preparing hexafluoro-1,3-butadiene and intermediate thereof

Info

Publication number: WO2021254372A1
Application number: PCT/CN2021/100290
Authority: WO
Inventors: 刘武灿; 吴海锋; 谢浩杰; 赵翀; 张建君
Original assignee: 浙江省化工研究院有限公司; 中化蓝天集团有限公司
Priority date: 2020-06-17
Filing date: 2021-06-16
Publication date: 2021-12-23
Also published as: KR20230029802A; JP2023538185A; CN111675597B; JP7411124B2; KR102750140B1; CN111675597A

Abstract

Disclosed is a method for preparing hexafluoro-1,3-butadiene and an intermediate thereof. The method for preparing hexafluoro-1,3-butadiene comprises: A1, reacting 1,2-dibromo-1-chloro-1,2,2-trifluoroethane with a trifluorohaloethylene in a polar aprotic solvent under the action of an initiator, and rectifying and purifying the reaction solution to obtain 1,4-dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane, wherein the structural formula of the trifluorohaloethylene is CF2=CFX, with X being Cl, Br or I, and the initiator is selected from at least one of azodiisobutyronitrile, di-tert-butyl peroxide, dibenzoyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, potassium persulfate and ammonium persulfate; and A2, subjecting 1,4-dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane and zinc powder to a dehalogenation reaction, in order to obtain hexafluoro-1,3-butadiene. The preparation method has advantages such as a simple process, mild reaction conditions, and being suitable for industrial production.

Description

A preparation method of hexafluoro-1,3-butadiene and its intermediates

Technical field

The invention relates to a fluorine-containing electronic gas, in particular to a method for synthesizing hexafluoro-1,3-butadiene and its intermediates by a telomerization method.

Background technique

Hexafluoro-1,3-butadiene, English name Hexafluoro-1,3-butadiene, HFBD for short, boiling point 5.5℃, freezing point -130℃, liquid density at 15℃ is 1.44kg/L. Hexafluoro-1,3-butadiene is a new generation of green dry etching gas, with excellent environmental performance and working performance, its existence time in the atmosphere (ALT) is only 1.9 days, and the GWP ₁₀₀ value is 290. Because hexafluoro-1,3-butadiene has a low fluorine-to-carbon ratio, it exhibits excellent etching performance. It is used for the etching of rectifier circuit boards containing Cu and low K dielectric constant. It is mainly used For precision etching of critical dimensions (accuracy of 100nm), it has better selectivity and aspect ratio than other etching gases. As one of the necessary materials for the production of high-end chips, hexafluoro-1,3-butadiene is a key etching gas for the new generation of storage technology 3D NAND flash memory. As the demand for high-end chips continues to increase, the market for hexafluoro-1,3-butadiene will continue to grow.

There are mainly the following reports on the synthesis of hexafluoro-1,3-butadiene in the prior art:

1) Process using chlorine and iodine as raw materials

Zhejiang Borui Electronics Patent CN106336342A discloses a method for synthesizing hexafluoro-1,3-butadiene using chlorine and iodine as raw materials. The method includes the following steps: ①The reaction of chlorine and iodine to synthesize iodine chloride; ②Trichlorochloride The reaction of ethylene with iodine chloride gives 1,2-dichloro-1,1,2-trifluoro-2-iodoethane (CF ₂ Cl-CFICl); ③1,2-dichloro-1,1,2-tri Fluoro-2-iodoethane undergoes intermolecular coupling reaction in the presence of a catalyst to obtain 1,2,3,4-tetrachloro-hexafluorobutane (CF ₂ Cl-CFCl-CFCl-CF ₂ Cl); ④1 ,2,3,4-Tetrachloro-hexafluorobutane undergoes intramolecular dehalogenation to obtain hexafluoro-1,3-butadiene. The reaction equation is as follows:

However, this method has longer steps and uses expensive iodine chloride, which makes the process raw material cost higher.

2) Dimerization process

Russian patent RU0118462 discloses a method for synthesizing hexafluoro-1,3-butadiene with chlorotrifluoroethylene as a raw material. The method includes: dimerization of chlorotrifluoroethylene at high temperature to obtain 34% of 1,2- Dichlorohexafluorocyclobutane and 27% of 3,4-dichlorohexafluoro-1-butene, and the two products, 3,4-dichlorohexafluoro-1-butene, are separated through a high-efficiency rectification column Direct zinc powder dechlorination to obtain the target product hexafluoro-1,3-butadiene, the reaction equation is as follows:

However, the polymerization reaction of this method requires high temperature and high pressure conditions, and the reaction selectivity is only 27%.

3) Zinc reagent coupling process

Zhejiang Lantian Environmental Protection Patent CN105732301A discloses that trifluoroethylene bromide is used as raw material to react with zinc powder to synthesize trifluorovinyl zinc reagent, and then under the action of trivalent iron salt or divalent copper salt, the self-coupling reaction obtains hexafluoro- The 1,3-butadiene method, the reaction equation is as follows:

However, the source of the starting material of this method, bromotrifluoroethylene, has problems.

4) Elemental fluorination process

Solvay patent WO2009087067A1 discloses a method for synthesizing hexafluoro-1,3-butadiene using trichloroethylene (TCE) and fluorine gas as raw materials. The method includes: ① Fluorine dimerization reaction: In an AISI 316L reactor, TCE reacts with fluorine gas diluted with helium to obtain C ₄ H ₂ F ₂ Cl ₆ , the conversion rate of TCE is 22.9%, and the selectivity is 50%; ② Elimination reaction: In a glass reactor, C ₄ H ₂ F ₂ Cl ₆ React with 20% NaOH solution to obtain tetrachlorodifluorobutadiene (CFCl=CCl-CCl=CFCl), the reaction yield is 93%; ③Fluorination reaction: Dilute tetrachlorodifluorobutadiene with helium Fluorine gas reaction produces tetrachlorohexafluorobutane (CF2Cl-CFCl-CFCl-CF2Cl, CFC-316), the reaction conversion rate is 97.8%, the selectivity is 64%; ④Dehalogenation reaction: CFC-316 in isopropanol solvent The hexafluoro-1,3-butadiene is obtained by reacting with zinc powder with a yield of 96% and a product purity of 99.5%. However, this method has higher requirements for equipment and high process safety risks.

Therefore, there is still a need to develop a new synthesis process of hexafluoro-1,3-butadiene.

Summary of the invention

In order to solve the above technical problems, the present invention proposes a method for preparing hexafluoro-1,3-butadiene and its intermediates by a telomerization method. The method has simple process, mild reaction conditions, small amount of three wastes, safety and environmental protection, Suitable for industrial production.

The purpose of the present invention is achieved through the following technical solutions:

A preparation method of hexafluoro-1,3-butadiene, the preparation method comprising the following steps:

A1. In a polar aprotic solvent, under the action of an initiator, 1,2-dibromo-1-chloro-1,2,2-trifluoroethane reacts with trifluoroethylene halide, and the reaction solution is purified to obtain 1 ,4-Dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane (Intermediate A); the structural formula of the trifluoroethylene halide is: CF ₂ = CFX, where X is Cl, Br or I;

The initiator is selected from azobisisobutyronitrile (AIBN), di-tert-butyl peroxide (DTBP), dibenzoyl peroxide (BPO), dicumyl peroxide (DCP), tert-butyl peroxide At least one of hydrogen oxide (TBHP), potassium persulfate (KPS), and ammonium persulfate (APS);

A2. 1,4-Dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane and zinc powder undergo dehalogenation reaction to obtain hexafluoro-1,3-butane Diene.

In the present invention, different initiation methods (such as photoinitiation or initiator initiation) have a greater impact on the synthesis of intermediate A. Although in terms of reaction mechanism, step A1 can be regarded as a free radical reaction, both photoinitiation and initiator initiation can initiate a free radical reaction. However, the applicant found that the initiation effect of the initiator is far better than that of photoinitiation for the reaction in step A1, and even different types of initiators have different initiation effects. That is, the use of initiators can increase the selectivity of intermediate A. Preferably, the initiator is selected from at least one of di-tert-butyl peroxide, dibenzoyl peroxide, and tert-butyl hydroperoxide. More preferably, the initiator is dibenzoyl peroxide or tert-butyl hydroperoxide.

Further, the molar ratio of the 1,2-dibromo-1-chloro-1,2,2-trifluoroethane to the initiator is 1:0.01 to 1:0.1. Preferably, the molar ratio of the 1,2-dibromo-1-chloro-1,2,2-trifluoroethane to the initiator is 1:0.03 to 1:0.06.

In the preparation process of the intermediate in step A1 of the present invention, the aprotic polar solvent is more conducive to the progress of the reaction. Preferably, the aprotic polar solvent is selected from tetrahydrofuran, 1,4-dioxane, acetonitrile, diethylene glycol dimethyl ether, N,N-dimethylformamide, N,N-dimethyl At least one of acetamide. More preferably, the polar aprotic solvent is selected from at least one of 1,4-dioxane, acetonitrile, and diethylene glycol dimethyl ether.

In the preparation process of the intermediate in step A1 of the present invention, the inert gas atmosphere is more conducive to the progress of the reaction. Preferably, the inert gas is selected from at least one of nitrogen, helium, and argon.

In the preparation process of the intermediate in step A1 of the present invention, the purification of the reaction solution can be carried out by a conventional purification method, such as atmospheric distillation or vacuum distillation.

In the preparation process of hexafluoro-1,3-butadiene in step A2 of the present invention, the reaction can be carried out in a solvent-free state. Of course, the reaction effect is better in organic solvents. Preferably, the organic solvent is selected from formic acid, acetic acid, trifluoroacetic acid, propionic acid, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, 1,1,1-trichloroethane, isopropyl At least one of alcohol, tert-butanol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, and hexamethylphosphoramide. More preferably, the organic solvent is selected from at least one of acetic acid, N,N-dimethylformamide or isopropanol.

In the preparation process of hexafluoro-1,3-butadiene in step A2 of the present invention, the presence of a catalyst is more favorable for the reaction to proceed. Preferably, the catalyst is selected from at least one of zinc chloride (ZnCl ₂ ), zinc bromide (ZnBr ₂ ) or zinc iodide (ZnI ₂ ), elemental iodine, and 1,2-dibromoethane; The molar ratio of body A to catalyst is 1:0.01 to 1:0.1. More preferably, the molar ratio of the intermediate A to the catalyst is 1:0.03 to 1:0.06.

In the preparation method of hexafluoro-1,3-butadiene of the present invention, as a preferred mode, the reaction temperature in the A1 step is 60°C to 200°C, and the temperature is kept for 1 to 12 hours; The reaction temperature is 40°C to 150°C, and the reaction is kept for 1 to 24 hours.

As a more preferred way, the reaction temperature in the A1 step is 80°C to 160°C, and the temperature is kept for 6-12 hours; the reaction temperature in the A2 step is 60°C to 90°C, and the temperature is kept for 3 to 6 hours. .

The present invention also provides a preparation method of 1,4-dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane, the preparation method comprising:

In a polar aprotic solvent, under the action of an initiator, 1,2-dibromo-1-chloro-1,2,2-trifluoroethane reacts with trifluoroethylene halide in an inert gas atmosphere. 1,4-Dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane is obtained by distillation and purification; the structural formula of the trifluoroethylene halide is: CF2=CFX , Where X is Cl, Br or I;

The initiator is selected from azobisisobutyronitrile (AIBN), di-tert-butyl peroxide (DTBP), dibenzoyl peroxide (BPO), dicumyl peroxide (DCP), tert-butyl peroxide At least one of hydrogen oxide (TBHP), potassium persulfate (KPS), and ammonium persulfate (APS).

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention adopts the telomerization reaction of 1,2-dibromo-1-chloro-1,2,2-trifluoroethane and trifluoroethylene to prepare the intermediate of hexafluoro-1,3-butadiene, The process is simple, the reaction conditions are mild, and it is suitable for industrial production.

2. The present invention uses a free radical initiator to initiate the telomerization reaction, which not only can control the rate of free radical generation and the degree of telomerization reaction, but also greatly improves the selectivity of the intermediate compared with photoinitiation.

detailed description

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to these specific embodiments. Those skilled in the art should realize that the present invention covers all alternatives, improvements and equivalents that may be included in the scope of the claims.

Example 1

This embodiment provides a method for preparing hexafluoro-1,3-butadiene. The preparation method includes an intermediate preparation step and a hexafluoro-1,3-butadiene preparation step, which are specifically as follows:

A1. Preparation of 1,4-dibromo-2,3-dichloro-1,1,2,3,4,4-hexafluorobutane

Add 150g of acetonitrile, 69.1g (0.25mol) of 1,2-dibromo-1-chloro-1,2,2-trifluoroethane, and diphenylmethyl peroxide into a 500mL Hastelloy pressure-bearing reactor 1.8g (7.5mmol) of acyl acid, _{purged with high-purity N 2 for} 10 minutes, then pour 34.8g (0.30mol) of chlorotrifluoroethylene from a steel cylinder into the reactor, and heat up to 80 under mechanical stirring (300-500r/min) ℃, the pressure of the reactor was increased to about 0.5MPa, and the temperature was kept for 12 hours to complete the reaction.

The reaction solution was analyzed by GC-MS, and calculations showed that the conversion rate of the raw material 1,2-dibromo-1-chloro-1,2,2-trifluoroethane was 98.75%, and the intermediate 1,4-dibromo- The selectivity of 2,3-dichloro-1,1,2,3,4,4-hexafluorobutane is 59.09%. The results are shown in Table 1.

The reaction solution is subjected to vacuum distillation to obtain high-purity intermediate A.

A2. Preparation of hexafluoro-1,3-butadiene

A 500 mL three-necked flask equipped with magnetic stirring, thermometer, condenser and dropping funnel was charged with 150 g of isopropanol, 2.0 g of elemental iodine, and 130 g (2.0 mol) of zinc powder. The top of the condenser is connected to the product collection bottle through a gas path, and the product collection tank is placed in a cryogenic cold trap (liquid nitrogen cooling). The reaction flask was heated to 70°C, and 1,4-dibromo-2,3-dichloro-1,1,2,3,4,4-hexafluorobutane 275g (purity 96%, 0.7mol) was added dropwise under magnetic stirring ), and collect the product, drip it in about 1h. After dripping, the temperature was raised to 80°C and kept for 3h, and the reaction was completed. The product collected in the cold trap was characterized by GC-MS and NMR, and it was hexafluoro-1,3-butadiene. The product obtained was 97.0 g with a purity of 96.6% and a yield of 86.0%. The results are shown in Table 3.

Example 2

The operation of this embodiment is the same as that of Embodiment 1, the only difference is:

During the preparation of the intermediate, the type of initiator was changed, and 1.1 g (7.5 mmol) of di-tert-butyl peroxide was used instead of dibenzoyl peroxide in Example 1. The results of the reaction are shown in Table 1.

During the preparation process of hexafluoro-1,3-butadiene, the type of catalyst was changed, and the elemental iodine in Example 1 was replaced with 2.5 g of zinc iodide to obtain 89.20 g of the product. The results are shown in Table 3.

Example 3

During the preparation of the intermediate, the type of initiator was changed, and 0.68 g (7.5 mmol) of tert-butyl hydroperoxide was used instead of dibenzoyl peroxide in Example 1; the reaction results are shown in Table 1.

In the preparation process of hexafluoro-1,3-butadiene, the type of catalyst was changed, and the elemental iodine in Example 1 was replaced with 1.5 g of 1,2-dibromoethane to obtain 95.0 g of the product. The results are shown in Table 3.

Example 4

During the preparation of the intermediate, the reaction temperature dropped from 80°C to 60°C; the reaction results are shown in Table 1.

During the preparation of hexafluoro-1,3-butadiene, the reaction temperature was reduced from 70°C to 60°C, and 76.20 g of the product was obtained. The results are shown in Table 3.

Example 5

During the preparation of the intermediate, the reaction temperature increased from 80°C to 100°C. The results of the reaction are shown in Table 1.

During the preparation process of hexafluoro-1,3-butadiene, the reaction temperature was increased from 70°C to 90°C to obtain 101.3 g of the product. The results are shown in Table 3.

Example 6

During the preparation of the intermediate, the type of solvent was changed, and 150 g of diethylene glycol dimethyl ether was used instead of acetonitrile in Example 1. The results of the reaction are shown in Table 1.

In the preparation process of hexafluoro-1,3-butadiene, the type of solvent was changed, and 150 g of N,N-dimethylacetamide was used instead of isopropanol in Example 1, to obtain 80.50 g of product. The results are shown in Table 3.

Example 7

During the preparation of the intermediate, the material ratio was changed, and the amount of chlorotrifluoroethylene was changed from 34.8g (0.30mol) to 58.0g (0.50mol). The results of the reaction are shown in Table 1.

During the preparation of hexafluoro-1,3-butadiene, the material ratio was changed, and the amount of zinc powder was changed from 130g (2.0mol) to 91.0g (1.4mol). 68.4 g of product was obtained. The results are shown in Table 3.

Example 8

A1. Preparation of 1,2,4-tribromo-3-chloro-1,1,2,3,4,4-hexafluorobutane

Add 150g of acetonitrile, 69.1g (0.25mol) of 1,2-dibromo-1-chloro-1,2,2-trifluoroethane, and di-tert-butyl peroxide to a 500mL Hastelloy pressure-bearable reactor Base 1.1g (7.5mmol), purged with high-purity N2 for 10 minutes, then pour 48.3g (0.30mol) of bromotrifluoroethylene from a steel cylinder into the reaction kettle, and heat up to 100℃ under mechanical stirring (300-500r/min) , The pressure of the reactor is increased to about 0.6MPa, and the temperature is kept for 12 hours to complete the reaction.

The reaction liquid was analyzed by GC-MS, and calculations showed that the conversion rate of the raw material 1,2-dibromo-1-chloro-1,2,2-trifluoroethane was 97.6%, and the intermediate 1,2,4-trifluoroethane The selectivity of bromo-3-chloro-1,1,2,3,4,4-hexafluorobutane is 73.9%. The results are shown in Table 2.

A2. Preparation of hexafluoro-1,3-butadiene

In a 500 mL three-necked flask equipped with magnetic stirring, thermometer, condenser and dropping funnel, 150 g of acetic acid, 2.0 g of elemental iodine, and 130 g (2.0 mol) of zinc powder were added. The top of the condenser is connected to the product collection bottle through a gas path, and the product collection tank is placed in a cryogenic cold trap (liquid nitrogen cooling). The reaction flask was heated to 60°C, and 312.3g of 1,2,4-tribromo-3-chloro-1,1,2,3,4,4-hexafluorobutane (purity 98%, 0.7mol) was added dropwise under magnetic stirring ), and collect the product, drip it in about 2h. After dripping, the temperature was raised to 80°C and kept for 3h, and the reaction was completed. The product collected in the cold trap was characterized by GC-MS and NMR, and it was hexafluoro-1,3-butadiene. The obtained product was 78.20 g with a purity of 97.5% and a yield of 69.9%. The results are shown in Table 3.

Example 9

The operation of this embodiment is the same as that of Embodiment 8. The only difference is:

During the preparation of the intermediate, the type of solvent was changed, and the acetonitrile in Example 7 was replaced with 150 g of diethylene glycol dimethyl ether. The results of the reaction are shown in Table 2.

In the process of preparing hexafluoro-1,3-butadiene, the type of solvent was changed, and 150 g of N,N-dimethylacetamide was used instead of acetic acid in Example 7 to obtain 82.50 g of product. The results are shown in Table 3.

Example 10

During the preparation of the intermediate, the reaction temperature increased from 100°C to 160°C. The results of the reaction are shown in Table 2.

In the process of preparing hexafluoro-1,3-butadiene, the type of catalyst was changed, 2.5 g of zinc iodide was used instead of elemental iodine in Example 7, to obtain 72.2 g of product. The results are shown in Table 3.

Example 11

During the preparation of the intermediate, the material ratio was changed, and the amount of bromotrifluoroethylene was changed from 48.3g (0.30mol) to 40.3g (0.25mol). The results of the reaction are shown in Table 2.

In the preparation process of hexafluoro-1,3-butadiene, the amount of iodine element of the catalyst was increased from the original 2.0g to 4.0g to obtain 74.5g of the product. The results are shown in Table 3.

Comparative example 1

During the preparation of the intermediate, the initiator dibenzoyl peroxide is not added. The results of the reaction are shown in Table 1.

During the preparation process of hexafluoro-1,3-butadiene, without adding catalyst elemental iodine, 78.50 g of the product was obtained. The results are shown in Table 3.

Comparative example 2

Add 276.3g (1.0mol) of 1,2-dibromo-1-chloro-1,2,2-trifluoroethane into a glass photoreactor with a jacket cold trap, and insert a 400W ultraviolet high-pressure mercury lamp. Turn on the low-temperature cycle (0°C), turn on the high-pressure mercury lamp, and slowly feed chlorotrifluoroethylene (50 mL/min), a total of 139.2 g (1.2 mol), and complete the flow in about 10 hours. Turn off the high-pressure mercury lamp and low-temperature circulation after the passage, the reaction liquid is analyzed by GC-MS, and calculations show that the conversion rate of the raw material 1,2-dibromo-1-chloro-1,2,2-trifluoroethane is 54.5 %, the selectivity of intermediate 1,4-dibromo-2,3-dichloro-1,1,2,3,4,4-hexafluorobutane is 38.2%. The results are shown in Table 1.

Table 1 The result of telomerization reaction with chlorotrifluoroethylene as raw material

Remarks: a. Remove the solvent peak and chlorotrifluoroethylene from the components;

b. The chromatographic content and actual content of each material are not corrected.

Table 2 The result of telomerization reaction with bromotrifluoroethylene as raw material

Remarks: a. Remove the solvent peak and bromotrifluoroethylene peak from the components;

Table 3 Dehalogenation reaction result table

Claims

A preparation method of hexafluoro-1,3-butadiene, characterized in that: the preparation method comprises the following steps:

A1. In a polar aprotic solvent, under the action of an initiator, 1,2-dibromo-1-chloro-1,2,2-trifluoroethane reacts with trifluoroethylene halide, and the reaction solution is purified to obtain 1 ,4-Dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane; the structural formula of the trifluoroethylene halide is: CF 2 =CFX, where X is Cl, Br or I;

The initiator is selected from the group consisting of azobisisobutyronitrile, di-tert-butyl peroxide, dibenzoyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, potassium persulfate, and ammonium persulfate At least one

A2.1,4-Dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane and zinc powder undergo dehalogenation reaction to obtain hexafluoro-1,3-butane Diene.
The method for preparing hexafluoro-1,3-butadiene according to claim 1, characterized in that: the 1,2-dibromo-1-chloro-1,2,2-trifluoroethane and the initiator The molar ratio of the agent is 1:0.01 to 1:0.1.
The method for preparing hexafluoro-1,3-butadiene according to claim 1, wherein the A1 step is reacted in an inert gas atmosphere, and the inert gas is selected from at least nitrogen, helium, and argon. A sort of.
The method for preparing hexafluoro-1,3-butadiene according to claim 3, wherein the polar aprotic solvent is selected from tetrahydrofuran, 1,4-dioxane, acetonitrile, diethylenediene At least one of dimethyl ether, N,N-dimethylformamide, and N,N-dimethylacetamide.
The method for preparing hexafluoro-1,3-butadiene according to claim 1, wherein the step A2 is reacted in the presence of a catalyst, and the catalyst is selected from zinc bromide, zinc iodide or iodine. At least one of them.
The method for preparing hexafluoro-1,3-butadiene according to claim 5, wherein the 1,4-dibromo-2-chloro-3-halo-1,1,2,3 The molar ratio of 4,4-hexafluorobutane to catalyst is 1:0.01 to 1:0.1.
The method for preparing hexafluoro-1,3-butadiene according to claim 1, wherein the step A2 is reacted in an organic solvent, and the organic solvent is selected from the group consisting of formic acid, acetic acid, trifluoroacetic acid, propylene Acid, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, 1,1,1-trichloroethane, isopropanol, tert-butanol, N,N-dimethylformamide, N,N -At least one of dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone or hexamethylphosphoramide.
The method for preparing hexafluoro-1,3-butadiene according to claim 1, wherein the reaction temperature in the A1 step is 60°C to 200°C, and the temperature is kept for 1 to 12 hours; the A2 step The reaction temperature is 40°C to 150°C, and the temperature is kept for 1 to 24 hours.
The method for preparing hexafluoro-1,3-butadiene according to claim 8, wherein the reaction temperature in the A1 step is 80°C to 160°C, and the temperature is kept for 6 to 12 hours; the A2 step The reaction temperature is 60°C to 90°C, and the reaction is kept warm for 3 to 6 hours.
A preparation method of 1,4-dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane, characterized in that: the preparation method comprises:

In a polar aprotic solvent, under the action of an initiator, 1,2-dibromo-1-chloro-1,2,2-trifluoroethane reacts with trifluoroethylene halide in an inert gas atmosphere. 1,4-Dibromo-2-chloro-3-halo-1,1,2,3,4,4-hexafluorobutane is obtained by distillation and purification; the structural formula of the trifluoroethylene halide is: CF 2 = CFX, where X is Cl, Br or I;

The initiator is selected from the group consisting of azobisisobutyronitrile, di-tert-butyl peroxide, dibenzoyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, potassium persulfate, and ammonium persulfate At least one.