Synthesis process of octafluorocyclobutane

Abstract

The invention relates to a synthesis process of octafluorocyclobutane, which comprises the following steps: taking dichlorohexafluorocyclobutane and hydrogen fluoride as raw materials, adding a lewis acid substance antimony pentachloride or fluorocobaltate as a catalyst to catalyze the raw materials to react, generating octafluorocyclobutane through circular reaction, and then purifying and separating the generated octafluorocyclobutane. The catalyst used in the method is simple and easy to obtain, the temperature in the reaction process is low, energy consumption is low, and the whole technological process is easy to amplify. The problems that in the prior art, a catalyst for reaction is difficult to obtain, energy consumption is high due to high reaction temperature, and the process is complex and not easy to popularize and amplify are solved.

Description

Technical Field

[0001] This invention relates to the field of organic compound synthesis, and particularly to a process for synthesizing octafluorocyclobutane. Background Technology

[0002] Octafluorocyclobutane is typically a byproduct of the cracking of tetrafluoroethylene to hexafluoropropylene, accounting for approximately 10-20% of the total yield. Purification of this byproduct yields pure octafluorocyclobutane. Several specific technical solutions for the synthesis of octafluorocyclobutane have been publicly disclosed in the existing technology.

[0003] The invention patent with patent number CN 119956374 A discloses a method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane. Dichlorohexafluorocyclobutane is added to a mixture of potassium fluoride and anhydrous hydrogen fluoride, and then heated and electrolyzed to obtain crude octafluorocyclobutane. Moisture and hydrogen fluoride are then removed using molecular sieves and an absorption tower to obtain the product. However, hydrogen fluoride in this electrolysis method is highly corrosive, difficult to separate, and has high separation costs, making it difficult to scale up the reaction process.

[0004] The invention patent CN114956950 B discloses a method for synthesizing octafluorocyclobutane using a fluorine-chlorine exchange reaction. This method involves fluorinating a Cr2O3-NiO catalyst supported on activated carbon with hydrogen fluoride, then catalyzing the reaction of hydrogen fluoride with 1,1,2,2,3,4-hexafluoro-3,4-dichlorocyclobutane to produce crude octafluorocyclobutane, which is then purified by distillation. However, this method involves complex catalyst preparation processes, a reaction temperature of 350℃~550℃, and relatively high energy consumption. Summary of the Invention

[0005] The main objective of this invention is to propose a synthesis process for octafluorocyclobutane to solve the problems of complex catalyst preparation, high reaction temperature, complex purification, and difficulty in scaling up the reaction process in the prior art.

[0006] This invention discloses a synthesis process for octafluorocyclobutane, comprising the following steps: adding dichlorohexafluorocyclobutane and hydrogen fluoride as raw materials to a reaction vessel, and adding a catalyst to catalyze the reaction of the raw materials to generate octafluorocyclobutane, wherein the catalyst is a Lewis acid or a fluorocobaltate.

[0007] Preferably, the Lewis acid is one or more of the following: antimony pentachloride, antimony tetrafluorochloride, antimony trifluorochloride, antimony difluorochloride, antimony tetrafluoromonochloride, and antimony pentafluoride; The fluorocobaltate is KCoF4.

[0008] Preferably, the feed rate of the dichlorohexafluorocyclobutane into the reaction vessel is 116.5~210 g / h, and the feed rate of the hydrogen fluoride is 21~37.8 g / h.

[0009] Preferably, the reaction temperature is 50~150℃ and the reaction pressure is 0.5~1.5MPa.

[0010] Preferably, the hydrogen fluoride and the dichlorohexafluorocyclobutane are introduced into the reaction vessel after being preheated to 50-150°C.

[0011] Preferably, the synthesis reaction further includes the following steps: S2. Under the catalytic conditions of the catalyst, the gaseous material generated after the reaction of the raw materials in the reaction vessel is sent to the reactive distillation device for distillation, and the liquid material formed in the reactive distillation device is returned to the reaction vessel to form a circulating reaction. S3. The crude octafluorocyclobutane gas formed in the reactive distillation unit enters the hydrogen chloride distillation unit for distillation to obtain the product octafluorocyclobutane and the impurity hydrogen chloride gas. Then, the impurity hydrogen chloride gas in the hydrogen chloride distillation unit is discharged, and the octafluorocyclobutane is continuously collected.

[0012] The gaseous materials formed in the reaction vessel include octafluorocyclobutane, hydrogen fluoride, dichlorohexafluorocyclobutane, and heptafluorocyclobutane. After being distilled in a reactive distillation unit, the resulting liquid materials include hydrogen fluoride, dichlorohexafluorocyclobutane, and heptafluorocyclobutane. These products are then returned to the reaction vessel for further reaction, and this process is repeated. The crude octafluorocyclobutane gas formed in the reactive distillation unit consists of octafluorocyclobutane and the byproduct hydrogen chloride. This crude octafluorocyclobutane gas is fed into a hydrogen chloride distillation unit to separate the octafluorocyclobutane and hydrogen chloride. Ultimately, hydrogen chloride is discharged as an impurity gas, while octafluorocyclobutane is collected as a liquid product.

[0013] Preferably, the pressure inside the reaction device is 0.5~1.5 MPa, the condensation temperature is -10~80 ℃, the bottom vaporization temperature is 50~120 ℃, and the reflux ratio is total reflux.

[0014] Preferably, the pressure inside the hydrogen chloride distillation apparatus is 0.4~1.4 MPa, the condensation temperature is -30~30 ℃, the bottom vaporization temperature is 0~85 ℃, and the reflux ratio is total reflux.

[0015] Preferably, the synthesis process of the octafluorocyclobutane is as follows: S1. The dichlorohexafluorocyclobutane and the hydrogen fluoride, as raw materials, are preheated at 50~150 °C and then fed into the reactor at feed rates of 116.5~210 g / h and 21~37.8 g / h, respectively. 30~300g of the catalyst is added to catalyze the reaction of the raw materials. The catalyst is a Lewis acid, antimony pentachloride or KCoF4. The reaction temperature inside the reactor is 50~150℃, and the reaction pressure is 0~2.5 MPa; S2. The gaseous material generated in the reactor is sent to the reactive distillation column for distillation, and the liquid material generated in the reactive distillation column is returned to the reactor to continue the reaction, forming a cycle. The pressure inside the reactive distillation column is 0.5~1.5 MPa, the condensation temperature at the top of the column is 30~80 ℃, the vaporization temperature at the bottom of the column is 50~150 ℃, and it operates under total reflux. S3. The crude octafluorocyclobutane gas generated in the reactive distillation column enters the hydrogen chloride distillation column for distillation to obtain the finished octafluorocyclobutane and impurity hydrogen chloride gas. The pressure inside the hydrogen chloride distillation column is 0.4~1.4MPa, the condensation temperature at the top of the column is -30~10℃, the vaporization temperature at the bottom of the column is 25~82℃, and it is a total reflux column. Hydrogen chloride impurities are discharged at the top of the column, and the finished product octafluorocyclobutane is continuously collected from the bottom of the column.

[0016] Antimony pentachloride added to the reactor reacts with hydrogen fluoride to form antimony tetrachloride, antimony trifluoride, antimony trifluoride, antimony tetrafluoride, antimony pentafluoride, or a mixture of these substances. These mixtures further accelerate the catalytic reaction.

[0017] This invention synthesizes octafluorocyclobutane and hydrogen chloride from dichlorohexafluorocyclobutane via the reaction of hydrogen fluoride with Lewis acid or KCoF4 catalysts. The reaction temperature is 50-150 °C, resulting in low energy consumption. The catalytic process used in the reaction is simple, the reaction conditions are mild, and energy consumption is low. A distillation unit and reaction vessel are used in a cyclic operation, allowing the synthesis reaction and purification processes to proceed simultaneously. The removal of hydrogen chloride impurities is cost-effective, and the entire process is continuous and efficient, eliminating the need for complex hydrogen chloride removal methods. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is a simplified diagram of the reaction apparatus of the present invention.

[0020] The attached diagram includes: 1-Reaction vessel, 2-Reaction distillation column, 3-Hydrochloride distillation column. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. At the same time, the raw materials mentioned below that are not described in detail are all commercially available products; the method steps or synthesis methods not mentioned in detail are all method steps or synthesis methods known to those skilled in the art.

[0022] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

[0023] Reactor 1 and reactive distillation column 2 are pre-purged with nitrogen and evacuated to remove oxygen and moisture from the system. Then, the catalyst is drawn into reactor 1 using the system's negative pressure. Hydrogen fluoride and dichlorohexafluorocyclobutane are placed in separate storage tanks. After preheating the raw materials in the storage tanks to 50–150°C, dichlorohexafluorocyclobutane and hydrogen fluoride are continuously introduced into reactor 1 using metering pumps at mass rates of 116.5–210 g / h and 21–37.8 g / h, respectively. The top condenser is activated, and reactor 1 is gradually heated to above 50°C to activate the catalyst. The reaction then takes place in reactor 1. Preheating the raw materials shortens the reaction time, maintains stable reaction, inhibits the formation of low-temperature byproducts, and improves the conversion rate.

[0024] A heating jacket is installed on reactor 1 to maintain the reaction temperature at 50~150 ℃. The reaction temperature is relatively mild, the energy consumption is low, and there are fewer by-products generated due to the high temperature, which is conducive to improving the product conversion rate.

[0025] The gaseous components octafluorocyclobutane, hydrogen fluoride, dichlorohexafluorocyclobutane, and monochloroheptafluorocyclobutane in reactor 1 enter the lower part of reactive distillation column 2 through the outlet at the top of reactor 1. During distillation, the gas in reactive distillation column 2 is condensed at the top of the column, and the resulting liquid phases of hydrogen fluoride, dichlorohexafluorocyclobutane, and monochloroheptafluorocyclobutane are refluxed back into the column and then flow back into reactor 1 for a circulating reaction. The reaction and distillation occur simultaneously. The uncondensed gases octafluorocyclobutane and hydrogen chloride are then distilled in hydrogen chloride distillation column 3 after pressure regulation. Reactive distillation column 2 has 60 trays, an internal pressure of 0~1.5 MPa, a top condensation temperature of -10~80℃, a bottom temperature of 50~150℃, and total reflux of the liquid phase.

[0026] The gas entering the hydrogen chloride distillation column 3 participates in the distillation process within the column. The gaseous phase rises to the top condenser, where it condenses to form octafluorocyclobutane, which is then refluxed back into the column. The uncondensed gas is hydrogen chloride, which, after pressure regulation, is released at the top of the column at a mass rate of 27–57 g / h. The hydrogen chloride distillation column 3 has 60 trays, an internal pressure of 0.4–1.4 MPa, a top condensation temperature of -30–30 °C, a bottom temperature of 0–85 °C, and total reflux of the liquid phase. Octafluorocyclobutane is continuously collected from the bottom at a mass rate of 75–142 g / h.

[0027] Since octafluorocyclobutane and hydrogen chloride have boiling points of -6℃ and -85℃ respectively, which are quite different, only octafluorocyclobutane will liquefy during the distillation process, while hydrogen chloride gas is difficult to liquefy. When the reflux ratio of the distillation column is set to total reflux, the vaporized hydrogen chloride is discharged at the top of the column.

[0028] The reactive distillation column 2 and the hydrogen fluoride distillation column 3 used in this experiment are experimental distillation columns. The specifications of the reactive distillation column 2 are: column height 3m and column diameter ø38*3 mm. The specifications of the hydrogen fluoride distillation column 3 are: column height 3m and diameter ø38*3 mm.

[0029] The synthesis reaction and purification are carried out simultaneously through cyclic distillation, resulting in a continuous and efficient process. Lewis acids or fluorocobaltates are used as catalysts, which are readily available, and the reaction steps are simple. The cyclic reaction improves the utilization rate of raw materials and the product yield, while the purification process uses conventional distillation methods, which are easily implemented in large-scale production processes.

[0030] Example 1 90 g of antimony pentachloride was added to the reactor as a catalyst and diluted with dichlorohexafluorocyclobutane. After preheating the raw materials hydrogen fluoride and dichlorohexafluorocyclobutane at 50 °C, hydrogen fluoride was fed into the reactor at a rate of 21 g / h and dichlorohexafluorocyclobutane at a rate of 116.5 g / h. The reactor temperature was set to 50 °C.

[0031] The gaseous components generated in the reactor are fed into a reactive distillation column for distillation. The liquid components that flow back to the bottom of the column flow back into the reactor to react again. The liquid phase at the top of the column is completely refluxed. The temperature at the top of the column is 30 °C, the pressure inside the column is 0.5 MPa, and the temperature at the bottom of the column is 50 °C.

[0032] The gaseous components distilled from the reactive distillation column were then fed into a hydrogen chloride distillation column for the separation of octafluorocyclobutane and hydrogen chloride. The liquid phase at the top of the hydrogen chloride distillation column was completely refluxed. The column top condensation temperature was set at -30 °C, the internal pressure at 0.4 MPa, and the bottom temperature at 25 °C. The reaction and purification were carried out in a continuous cycle, producing 75 g / h of octafluorocyclobutane and 27 g / h of hydrogen chloride.

[0033] Example 2 90 g of antimony pentachloride was added to the reactor as a catalyst and diluted with dichlorohexafluorocyclobutane. After preheating the raw materials hydrogen fluoride and dichlorohexafluorocyclobutane at 60 °C, hydrogen fluoride was fed into the reactor at a rate of 23.5 g / h and dichlorohexafluorocyclobutane at a rate of 128.2 g / h. The reactor temperature was set to 60 °C.

[0034] The gaseous components generated in the reactor are fed into a reactive distillation column for distillation, while the liquid components refluxed to the bottom of the column are returned to the reactor for further reaction. The reactive distillation column is equipped with total reflux of the liquid phase at the top, with a top condensation temperature of 35°C, an internal pressure of 0.5 MPa, and a bottom temperature of 50°C.

[0035] The gaseous components distilled from the reactive distillation column were then fed into a hydrogen chloride distillation column for the separation of octafluorocyclobutane and hydrogen chloride. The liquid phase at the top of the hydrogen chloride distillation column was completely refluxed. The column top condensation temperature was set at -28°C, the internal pressure at 0.4 MPa, and the bottom temperature at 30°C. The reaction and purification processes were continuously cyclical, producing 110 g / h of octafluorocyclobutane and 40 g / h of hydrogen chloride.

[0036] Example 3 90 g of antimony pentachloride was added to the reactor as a catalyst and diluted with dichlorohexafluorocyclobutane. After preheating the raw materials hydrogen fluoride and dichlorohexafluorocyclobutane at 70 °C, hydrogen fluoride was fed into the reactor at a rate of 25.2 g / h and dichlorohexafluorocyclobutane at a rate of 139.8 g / h. The reactor temperature was set to 70 °C.

[0037] The gaseous components generated in the reactor are fed into a reactive distillation column for distillation. The liquid components that are refluxed back to the bottom of the column are then refluxed back into the reactor to undergo a new reaction. The liquid phase at the top of the reactive distillation column is completely refluxed. The temperature at the top of the column is 40 °C, the pressure inside the column is 0.7 MPa, and the temperature at the bottom of the column is 70 °C.

[0038] The gaseous components distilled from the reactive distillation column were then fed into a hydrogen chloride distillation column for the separation of octafluorocyclobutane and hydrogen chloride. The liquid phase at the top of the hydrogen chloride distillation column was completely refluxed. The column top condensation temperature was set at -26 °C, the internal pressure at 0.6 MPa, and the bottom temperature at 47 °C. The reaction and purification were carried out in a continuous cycle, producing 117 g / h of octafluorocyclobutane and 42 g / h of hydrogen chloride.

[0039] Example 4 90 g of antimony pentachloride was added to the reactor as a catalyst and diluted with dichlorohexafluorocyclobutane. After preheating the raw materials hydrogen fluoride and dichlorohexafluorocyclobutane at 80 °C, hydrogen fluoride was fed into the reactor at a rate of 29.4 g / h and dichlorohexafluorocyclobutane at a rate of 163.1 g / h. The reactor temperature was set to 80 °C.

[0040] The gaseous components generated in the reactor are fed into a reactive distillation column for distillation. The liquid components that flow back to the bottom of the column flow back into the reactor to re-react. The liquid phase at the top of the reactive distillation column is completely refluxed. The temperature at the top of the column is 45°C, the pressure inside the column is 0.8 MPa, and the temperature at the bottom of the column is 80°C.

[0041] The gaseous components distilled from the reactive distillation column were then fed into a hydrogen chloride distillation column for the separation of octafluorocyclobutane and hydrogen chloride. The liquid phase at the top of the hydrogen chloride distillation column was completely refluxed. The column top condensation temperature was set at -22°C, the internal pressure at 0.7 MPa, and the bottom temperature at 57°C. The reaction and purification processes were continuously cyclical, producing 137.2 g / h of octafluorocyclobutane and 50 g / h of hydrogen chloride.

[0042] Example 5 90 g of antimony pentachloride was added to the reactor as a catalyst and diluted with dichlorohexafluorocyclobutane. After preheating the raw materials hydrogen fluoride and dichlorohexafluorocyclobutane at 100 °C, hydrogen fluoride was fed into the reactor at a rate of 31.5 g / h and dichlorohexafluorocyclobutane at a rate of 174.8 g / h. The reactor temperature was set to 100 °C.

[0043] The gaseous components generated in the reactor are fed into a reactive distillation column for distillation. The liquid components that flow back to the bottom of the column flow back into the reactor to react again. The liquid phase at the top of the reactive distillation column is completely refluxed. The temperature at the top of the column is 50 °C, the pressure inside the column is 1.0 MPa, and the temperature at the bottom of the column is 100 °C.

[0044] The gaseous components distilled from the reactive distillation column were then fed into a hydrogen chloride distillation column for the separation of octafluorocyclobutane and hydrogen chloride. The liquid phase at the top of the hydrogen chloride distillation column was completely refluxed. The column top condensation temperature was set at -18 °C, the internal pressure at 0.9 MPa, and the bottom temperature at 63 °C. The reaction and purification were carried out in a continuous cycle, producing 138 g / h of octafluorocyclobutane and 50 g / h of hydrogen chloride.

[0045] Example 6 90 g of antimony pentachloride was added to the reactor as a catalyst and diluted with dichlorohexafluorocyclobutane. After preheating the raw materials hydrogen fluoride and dichlorohexafluorocyclobutane at 120 °C, hydrogen fluoride was fed into the reactor at a rate of 33.6 g / h and dichlorohexafluorocyclobutane at a rate of 186.4 g / h. The reactor temperature was set at 120 °C.

[0046] The gaseous components generated in the reactor are fed into a reactive distillation column for distillation. The liquid components that flow back to the bottom of the column flow back into the reactor to react again. The liquid phase at the top of the reactive distillation column is completely refluxed. The temperature at the top of the column is 70 °C, the pressure inside the column is 1.2 MPa, and the temperature at the bottom of the column is 120 °C.

[0047] The gaseous components distilled from the reactive distillation column were then fed into a hydrogen chloride distillation column for the separation of octafluorocyclobutane and hydrogen chloride. The liquid phase at the top of the hydrogen chloride distillation column was completely refluxed. The column top condensation temperature was set at -14°C, the internal pressure at 1.1 MPa, and the bottom temperature at 71°C. The reaction and purification processes were continuously cyclical, producing 142 g / h of octafluorocyclobutane and 52 g / h of hydrogen chloride.

[0048] Example 7 90 g of antimony pentachloride was added to the reactor as a catalyst and diluted with dichlorohexafluorocyclobutane. After preheating the raw materials hydrogen fluoride and dichlorohexafluorocyclobutane at 150 °C, hydrogen fluoride was fed into the reactor at a rate of 37.8 g / h and dichlorohexafluorocyclobutane at a rate of 210 g / h. The reactor temperature was set at 150 °C.

[0049] The gaseous components generated in the reactor are fed into a reactive distillation column for distillation. The liquid components that are refluxed back to the bottom of the column are then refluxed back into the reactor to undergo a new reaction. The liquid phase at the top of the reactive distillation column is completely refluxed. The temperature at the top of the column is 80 °C, the pressure inside the column is 1.5 MPa, and the temperature at the bottom of the column is 150 °C.

[0050] The gaseous components distilled from the reactive distillation column were then fed into a hydrogen chloride distillation column for the separation of octafluorocyclobutane and hydrogen chloride. The liquid phase at the top of the hydrogen chloride distillation column was completely refluxed. The column top condensation temperature was set at -10 °C, the internal pressure at 1.4 MPa, and the bottom temperature at 82 °C. The reaction and purification were carried out in a continuous cycle, producing 140 g / h of octafluorocyclobutane and 51 g / h of hydrogen chloride.

[0051] The yield and purity results of octafluorocyclobutane in Examples 1 to 7 are shown in Table 1.

[0052] Table 1 Comparative Example 1: The only difference between this comparative example and Example 3 is the amount of catalyst used. The experimental data are shown in Table 2. Table 2 As we can see from Comparative Example 1, the yield of octafluorocyclobutane gradually increases with the increase of antimony pentachloride content. However, when the amount of antimony pentachloride increases to more than 90g, the yield of octafluorocyclobutane decreases. This may be because the content of byproducts gradually increases with the increase of catalyst content, thus reducing the yield of octafluorocyclobutane.

[0053] Comparative Example 2: The only difference between this comparative example and Example 3 is the type of catalyst used. The experimental data are shown in Table 3. Table 3 The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A process for synthesizing octafluorocyclobutane, characterized in that, Includes the following steps: S1. Dichlorohexafluorocyclobutane and hydrogen fluoride are added to the reaction vessel as raw materials, and a catalyst is added to catalyze the reaction of the raw materials to generate octafluorocyclobutane. The catalyst is a Lewis acid or a fluorocobaltate.

2. The synthesis process of octafluorocyclobutane as described in claim 1, characterized in that, The Lewis acid is one or more of the following: antimony pentachloride, antimony tetrafluorochloride, antimony trifluorochloride, antimony difluorochloride, antimony tetrafluoromonochloride, and antimony pentafluoride; the fluorocobaltate is KCoF4.

3. The synthesis process of octafluorocyclobutane as described in claim 1 or 2, characterized in that, The feed rate of the dichlorohexafluorocyclobutane introduced into the reaction vessel is 116.5~210 g / h, and the feed rate of the hydrogen fluoride is 21~37.8 g / h.

4. The synthesis process of octafluorocyclobutane as described in claim 3, characterized in that, The reaction temperature inside the reaction vessel is 50~150℃, and the reaction pressure is 0~2.5 MPa.

5. The synthesis process of octafluorocyclobutane as described in claim 4, characterized in that, The hydrogen fluoride and the dichlorohexafluorocyclobutane are preheated to 50-150°C before being introduced into the reaction vessel.

6. The synthesis process of octafluorocyclobutane as described in claim 1, characterized in that, It also includes the following steps: S2. The raw materials in the reaction vessel react under the catalytic condition of the catalyst, and the resulting gaseous material is sent to the reactive distillation device for distillation. The liquid material formed in the reactive distillation device is returned to the reaction vessel to continue the reaction, forming a cycle. S3. The crude octafluorocyclobutane gas formed in the reactive distillation unit enters the hydrogen chloride distillation unit for distillation to obtain the finished octafluorocyclobutane and impurity hydrogen chloride gas. Subsequently, the impurity hydrogen chloride gas in the hydrogen chloride distillation unit is discharged, and octafluorocyclobutane is continuously collected in the bottom of the column.

7. The synthesis process of octafluorocyclobutane as described in claim 6, characterized in that, The reactive distillation apparatus has an internal pressure of 0~1.5 MPa, a condensation temperature of -10~80 ℃, a bottom vaporization temperature of 50~150 ℃, and a total reflux ratio.

8. The synthesis process of octafluorocyclobutane as described in claim 6, characterized in that, The hydrogen chloride distillation apparatus has an internal pressure of 0~1.4 MPa, a condensation temperature of -30~30 ℃, a bottom vaporization temperature of 0~85 ℃, and a reflux ratio of total reflux.

9. The synthesis process of octafluorocyclobutane as described in claim 6, characterized in that, The content of the catalyst is 30~300 g.

10. The synthesis process of octafluorocyclobutane as described in claim 6, characterized in that, The synthesis process of the octafluorocyclobutane is as follows: S1. The dichlorohexafluorocyclobutane and the hydrogen fluoride, as raw materials, are preheated at 50~150 °C and then fed into the reactor at feed rates of 116.5~210 g / h and 21~37.8 g / h, respectively. 30~300 g of the catalyst is added to catalyze the reaction of the raw materials. The catalyst is a Lewis acid, antimony pentachloride or KCoF4. The reaction temperature inside the reactor is 50~150℃, and the reaction pressure is 0~2.5 MPa; S2. The gaseous material generated in the reactor is sent to the reactive distillation column for distillation, and the liquid material generated in the reactive distillation column is returned to the reactor to continue the reaction, forming a cycle. The pressure inside the reactive distillation column is 0.5~1.5 MPa, the condensation temperature at the top of the column is 30~80 ℃, the vaporization temperature at the bottom of the column is 50~150 ℃, and it operates under total reflux. S3. The crude octafluorocyclobutane gas generated in the reactive distillation column enters the hydrogen chloride distillation column for distillation to obtain the finished octafluorocyclobutane and impurity hydrogen chloride gas. The pressure inside the hydrogen chloride distillation column is 0.4~1.4MPa, the condensation temperature at the top of the column is -30~10℃, the vaporization temperature at the bottom of the column is 25~82℃, and it is a total reflux column. Hydrogen chloride impurities are discharged at the top of the column, and the finished product octafluorocyclobutane is continuously collected from the bottom of the column.

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