Method for producing 1,4-dibromo-2,3-dichlorohexafluorobutane and method for producing hexafluoro-1,3-butadiene using the same

Abstract

A method for producing 1,4-dibromo-2,3-dichlorohexafluorobutane (Br-CF2-CFCl-CFCl-CF2-Br) is disclosed, which comprises photoreacting a 1,2-dibromo-1-chlorotrifluoroethane (Br-CF2-CFCl-Br) solution with a CTFE (CF2=CFCl) gas mixed with a diluent gas to produce 1,4-dibromo-2,3-dichlorohexafluorobutane. According to an embodiment of the present invention, an intermediate for producing hexafluoro-1,3-butadiene (C4F6) can be produced in high yield.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 2021-0125650, filed on September 23, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a method for producing 1,4-dibromo-2,3-dichlorohexafluorobutane and a method for producing hexafluoro-1,3-butadiene using the same. [Background technology]

[0003] Hexafluoro-1,3-butadiene (C4F6) is a specialty gas used as an etching gas in the semiconductor manufacturing process, and its demand is increasing as the integration density of semiconductor devices increases.

[0004] Various techniques for producing CF have been disclosed in several prior art documents. The techniques disclosed in these prior art documents include a method for producing X-CF-CFY-CFY-CF-X (X = Cl, Br, I, Y = Cl, Br, I, F) as an intermediate to easily produce CF. Since CF can be easily produced from such intermediates, the production cost of CF varies greatly depending on the method for producing the intermediate.

[0005] Examples of intermediate substances include the following:

[0006] [1]I-CF2-CF2-CF2-CF2-I

[0007] [2]Br-CF2-CF2-CF2-CF2-Br

[0008] [3]Cl-CF2-CFCl-CFCl-CF2-Cl

[0009] [4]Br-CF2-CFCl-CFCl-CF2-Br

[0010] Of these intermediate substances, substances [1] and [2] can be produced by the following schemes (1) and (2) using TFE (CF2 = CF2, Tetrafluoroethylene) as the starting material.

[0011] (1)CF2=CF2+X2(X=Br,I)→X-CF2-CF2-X

[0012] (2)X-CF2-CF2-X+CF2=CF2→X-CF2-CF2-CF2-CF2-X

[0013] The problem with the above-mentioned production method is that TFE is used as a starting material. To produce TFE, a thermal decomposition process of R-22 (CHClF2) must be carried out, and the construction of such a TFE production facility requires a large investment cost. In addition, the progress of scheme (2) requires a large amount of energy due to the strong bonding force of the fluorine atom (F), which results in the problem of the generation of various by-products.

[0014] Among the intermediate substances, substances [3] and [4] have the advantage that they can be produced using CTFE (CF2 = CFCl, chlorotrifluoroethylene) as a starting material, which is relatively easier to transport and purchase than TFE. Taking intermediate [3] as an example, it can be produced according to the following schemes (3) to (6).

[0015] (3)CF2=CFCl+I-Cl→Cl-(CF2-CFCl)-I

[0016] (4)2Cl-(CF2-CFCl)-I+Zn→CF2Cl-CFCl-CFCl-CF2Cl+ZnI2

[0017] (5) ZnI2 → Zn + I2

[0018] (6) I2 + Cl2 → 2I-Cl

[0019] In the scheme (3), I-Cl is used instead of iodine (I2) because the I atom of I-Cl reacts with the Cl atom of CTFE (CF2=CFCl), and the Cl atom of I-Cl reacts with the F atom of CTFE (CF2)=CFCl) with more F atoms, and then the deiodination reaction of scheme (4) is carried out to produce intermediate [3] (CF2Cl-CFCl-CFCl-CF2Cl).

[0020] However, when I-Cl is added to CTFE (CF2 = CFCl), I-(CF2-Cl)-Cl is generated as a by-product, resulting in a low intermediate production yield due to the production of Cl-CF2-CFCl-CF2-CFCl-Cl at a certain rate instead of the intermediate [3]. In addition, because iodine (I2) required for the production of I-Cl is expensive, the additional step of regenerating iodine (Scheme (5)) is required, making the overall reaction process complicated.

[0021] Alternative processes for preparing the intermediate [3] include the following schemes (7) and (8).

[0022] (7)CH2=CH-CH=CH2+2Cl2→CH2Cl-CHCl-CHCl-CH2Cl

[0023] (8)CH2Cl-CHCl-CHCl-CH2Cl+6F2→Cl-CF2-CFCl-CFCl-CF2-Cl+6HF

[0024] However, since this manufacturing process uses highly reactive fluorine (F2), it is difficult to control the generation of by-products during the reaction, and a fluorine (F2) electrolytic cell is required to produce fluorine (F2), which increases the manufacturing cost. Summary of the Invention [Problem to be solved by the invention]

[0025] The present invention is intended to solve the above-mentioned problems of the conventional art, and its object is to provide a method for producing an intermediate that enables C4F6 to be produced simply, safely, and at a relatively low production cost, and a method for producing C4F6 using such an intermediate.

[0026] Another object of the present invention is to provide a method for producing an intermediate that can improve the production yield of the intermediate by suppressing the production of high-boiling substances and / or isomers during the intermediate production process, and a method for producing C4F6 using the same.

[0027] However, the problems to be solved by the present application are not limited to the above-mentioned problems, and other problems not mentioned above will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0028] A method for producing 1,4-dibromo-2,3-dichlorohexafluorobutane (Br-CF-CFCl-CFCl-CF-Br) according to an embodiment of the present invention is characterized in that 1,4-dibromo-2,3-dichlorohexafluorobutane is produced by reacting a 1,2-dibromo-1-chlorotrifluoroethane (Br-CF-CFCl-Br) solution diluted with a solvent with CTFE (CF=CFCl) gas mixed with a diluent gas under light (UV) initiation.

[0029] The solvent may include MC (Methylene Chloride, CH2Cl2), and the content of the solvent in the 1,2-dibromo-1-chlorotrifluoroethane (Br-CF2-CFCl-Br) solution may be 90 mol % or less.

[0030] The diluent gas may include an inert gas.

[0031] Alternatively, the diluent gas may include a HFC (Hydrofluorocarbon) or PFC (Perfluorocarbon) gas.

[0032] Alternatively, the dilution gas may contain one or more inert gases together with one or more HFC (Hydrofluorocarbon) and PFC (Perfluorocarbon) gases.

[0033] The content of the CTFE gas in the total gas including the diluent gas and the CTFE gas may be 50 mol % or less.

[0034] In addition, the method for producing 1,4-dibromo-2,3-dichlorohexafluorobutane according to an embodiment of the present invention may further include a step of reacting CTFE (CF₂=CFCl) with bromine (Br₂) to produce 1,2-dibromo-1-chlorotrifluoroethane (Br—CF₂—CFCl—Br).

[0035] A method for producing hexafluoro-1,3-butadiene (CF) using a 1,4-dibromo-2,3-dichlorohexafluorobutane (Br-CF-CFCl-CFCl-CF-Br) intermediate according to an embodiment of the present invention includes a photoreaction step of producing 1,4-dibromo-2,3-dichlorohexafluorobutane by reacting a 1,2-dibromo-1-chlorotrifluoroethane (Br-CF-CFCl-Br) solution diluted with a solvent with CTFE (CF=CFCl) gas mixed with a diluent gas using light (UV) irradiation, and a dehalogenation step of releasing halogen atoms by removing fluorine atoms from the produced 1,4-dibromo-2,3-dichlorohexafluorobutane.

[0036] In this case, the dehalogenation step can be carried out in the presence of zinc (Zn) and isopropyl alcohol.

[0037] In addition, the method may further include a step of reacting CTFE (CF2=CFCl) with bromine (Br2) to produce 1,2-dibromo-1-chlorotrifluoroethane (Br-CF2-CFCl-Br) before the photoreaction step. [Effects of the Invention]

[0038] According to an embodiment of the present invention, CTFE, which is relatively easy to transport and purchase, is used as a starting material to produce 1,2-dibromo-1-chlorotrifluoroethane, a reaction material, which is then reacted with CTFE to produce 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate, from which CF is produced. This provides an advantage of providing a method for producing an intermediate and CF simply, safely, and at a relatively low production cost.

[0039] Furthermore, according to the embodiment of the present invention, the reaction raw material 1,2-dibromo-1-chlorotrifluoroethane is diluted with a solvent such as MC (Methylene Chloride, CHCl), and the diluted solution is reacted with CTFE by light (UV) initiation. In this reaction, a diluent gas containing an inert gas is used, which suppresses the production of high boiling points during the intermediate production process and improves the intermediate production yield.

[0040] Furthermore, according to an embodiment of the present invention, the reaction raw material 1,2-dibromo-1-chlorotrifluoroethane is diluted with a solvent such as MC (Methylene Chloride, CHCl), and the diluted solution is reacted with CTFE by light (UV) initiation using a diluent gas containing HFC or PFC gas, thereby suppressing the generation of isomers during the intermediate production process and improving the intermediate production yield.

[0041] However, the effects of the present invention are not limited to those described above, and other effects not described above will be clearly understood by those having ordinary skill in the art to which the present invention pertains from the following description. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is a flowchart of a method for producing 1,4-dibromo-2,3-dichlorohexafluorobutane (Br—CF—CFCl—CFCl—CF—Br) intermediate and C F according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0043] The present invention will be described in detail below. The following description includes specific embodiments, but the present invention is not limited or restricted by the described embodiments. In describing the present invention, if it is determined that a detailed description of related publicly known technologies may obscure the gist of the present invention, the detailed description will be omitted.

[0044] The present invention provides a method for producing 1,4-dibromo-2,3-dichlorohexafluorobutane (Br-CF-CFCl-CFCl-CF-Br) as an intermediate for producing C4F6, and further provides a method for producing C4F6 using the intermediate.

[0045] A flow chart of the method for producing 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate and C4F6 according to an embodiment of the present invention is shown in Figure 1.

[0046] Referring to FIG. 1, a method for producing a 1,4-dibromo-2,3-dichlorohexafluorobutane (Br—CF—CFCl—CFCl—CF—Br) intermediate according to an embodiment of the present invention may include a step S1 of reacting CTFE (CF═CFCl) with bromine (Br) to produce 1,2-dibromo-1-chlorotrifluoroethane (Br—(CF—CFCl)—Br), and a step S2 of producing a 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate by photo (UV)-initiated reaction of a 1,2-dibromo-1-chlorotrifluoroethane solution with CTFE in the presence of a diluent gas.

[0047] In addition, the method for producing C4F6 according to an embodiment of the present invention may include a dehalogenation step (step S3) of eliminating halogens other than fluorine from the 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate. Here, the dehalogenation reaction may be carried out using a metal such as zinc (Zn) in a solvent such as isopropyl alcohol.

[0048] Each step will be explained in more detail below.

[0049] <Production of 1,2-dibromo-1-chlorotrifluoroethane (Step S1)>

[0050] Step S1 is a step of reacting CTFE (CF═CFCl) with bromine (Br) to produce 1,2-dibromo-1-chlorotrifluoroethane (Br—(CF—CFCl)—Br), and can be performed according to the following scheme (9).

[0051] (9)CF2=CFCl+Br2→Br-(CF2-CFCl)-Br

[0052] The process of Scheme (9) can be carried out by simultaneously introducing gaseous CTFE and liquid bromine (Br2) into a Teflon tube immersed in an external thermostatic bath where the temperature is controlled. As the CTFE gas passes through the inside of the Teflon tube, it comes into contact with the liquid bromine to produce 1,2-dibromo-1-chlorotrifluoroethane. Excess CTFE that passes through the tube can be recovered from the end of the tube and reused.

[0053] <Production of 1,4-dibromo-2,3-dichlorohexafluorobutane (Step S2)>

[0054] Step S2 is a step of reacting 1,2-dibromo-1-chlorotrifluoroethane prepared in step S1 with a solvent to dilute the 1,2-dibromo-1-chlorotrifluoroethane solution with CTFE to produce 1,4-dibromo-2,3-dichlorohexafluorobutane, and can be carried out according to the following scheme (10).

[0055] (10)Br-(CF2-CFCl)-Br+CF2=CFCl→Br-CF2-CFCl-CFCl-CF2-Br

[0056] In this case, the S2 step can be carried out by photo (UV) initiation under a diluent gas.

[0057] The solvent used for the 1,2-dibromo-1-chlorotrifluoroethane solution is not limited to a specific solvent, and any solvent capable of stabilizing photo-initiated (UV) radicals can be used, preferably MC (Methylene Chloride, CHCl).

[0058] The dilution gas used in step S2 may be an inert gas such as nitrogen, helium, or argon. Alternatively, it may be an HFC (hydrofluorocarbon) gas such as R-23 (CHF), R32 (CHF), R-41 (CHF), R-134a (CFCHF), or R-125 (CFCHF), or a PFC (perfluorocarbon) gas such as CF, CF, or CF. Alternatively, a mixture of an inert gas and an HFC or PFC gas may be used. Preferably, a mixture of one or more inert gases and one or more gases selected from HFC and PFC gases may be used.

[0059] The process of scheme (10) can be carried out by filling a reactor equipped with a radical initiation lamp with a 1,2-dibromo-1-chlorotrifluoroethane solution as the reaction raw material, and then repeatedly performing vacuum formation and purging by supplying an inert gas. The diluent gas and CTFE gas can be circulated to the photoreactor using a compressor.

[0060] The 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate produced in the photoreactor and the 1,2-dibromo-1-chlorotrifluoroethane solution as the reaction raw material can be separated by being transferred to a separation tower, which can include a first separation tower and a second separation tower.

[0061] A mixture of the 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate produced in the photoreactor and the 1,2-dibromo-1-chlorotrifluoroethane reaction raw material solution can be transferred from the photoreactor to the first separation tower. The reaction raw material solution separated at the top of the first separation tower can be recycled to the photoreactor again and used for additional photoreactions.

[0062] A mixture of intermediates (photoreaction products), high-boiling by-products, and reactant materials can collect at the bottom of the first separation tower. When the concentration of intermediates in this mixture reaches a certain level, it can be transferred to the second separation tower for purification. In the second separation tower, the low-boiling reactant 1,2-dibromo-1-chlorotrifluoroethane solution is first separated and resupplied to the photoreactor, and then the intermediate 1,4-dibromo-2,3-dichlorohexafluorobutane is distilled and recovered. After the distillation and recovery of the intermediates is complete, the other high-boiling materials can be recovered separately at the bottom of the second separation tower for further processing.

[0063] The inert gas in the solvent and diluent gas used in the reaction can suppress the formation of high-boiling substances with boiling points higher than 1,4-dibromo-2,3-dichlorohexafluorobutane. Here, the high-boiling substances are Br-(CF2-CFCl) n —Br (n is an integer of 3 or greater). More specifically, the selectivity to products during the reaction can vary depending on the concentration of CTFE gas dissolved in the reaction raw material, 1,2-dibromo-1-chlorotrifluoroethane. The higher the concentration of CTFE gas, the more likely high-boiling substances are produced, while the lower the concentration of CTFE gas, the more likely high-boiling substances are produced, resulting in the production of 1,4-dibromo-2,3-dichlorohexafluorobutane. The proportion of 1,2-dibromo-1-chlorotrifluoroethane in the 1,2-dibromo-1-chlorotrifluoroethane solution is 10 to 100 mol %, and the proportion can be selected taking into account reactivity and selectivity.

[0064] The ratio of CTFE gas to diluent gas can be adjusted so that the content of CTFE gas is 1 to 50 mol %, preferably 1 to 25 mol %, of the total gas including the diluent gas and CTFE gas.

[0065] In addition, the HFC or PFC gas in the diluent gas can suppress the production of 1,4-dibromo-1,3-dichlorohexafluorobutane (Br-CF2-CFCl-CF2-CFCl-Br), an isomer of 1,4-dibromo-2,3-dichlorohexafluorobutane (Br-CF2-CFCl-CFCl-CF2-Br). As a result, by carrying out the reaction in the presence of a diluent gas, the production yield of the intermediate 1,4-dibromo-2,3-dichlorohexafluorobutane can be improved.

[0066] When using a diluent gas containing HFC or PFC gas that has little effect on UV light during the reaction, the radicals (

[0067] [ka]

[0068] ) is suppressed, and the radical (

[0069] [ka]

[0070] ) can be stably produced. As a result, by using a diluent gas containing an HFC or PFC gas during the photoreaction, the production of isomers can be suppressed and the production yield of the intermediate 1,4-dibromo-2,3-dichlorohexafluorobutane can be improved.

[0071] <Production of hexafluoro-1,3-butadiene (C4F6) (Step S3)>

[0072] Step S3 is a step of producing CF by removing halogens (Br, Cl) from the 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate produced in step S2, and zinc (Zn) metal and isopropyl alcohol solvent can be used for this purpose. Step S3 can be carried out according to the following scheme (11).

[0073] (11)Br-CF2-CFCl-CFCl-CF2-Br+2Zn / i-PrOH→C4F6+2ZnClBr

[0074] As described above, according to the embodiments of the present invention, CTFE, which is relatively easy to transport and purchase, is used as a starting material to produce a 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate, from which C4F6 is produced. This makes it possible to produce the intermediate and C4F6 at a relatively low production cost.

[0075] Furthermore, according to the examples of the present invention, when reacting 1,2-dibromo-1-chlorotrifluoroethane, which is a reaction raw material, with CTFE, 1,2-dibromo-1-chlorotrifluoroethane is diluted with a solvent, and a diluent gas containing an inert gas is used, thereby making it possible to suppress the production of high-boiling substances in the intermediate production process and improve the production yield of the intermediate.

[0076] Furthermore, according to the embodiments of the present invention, when reacting the raw materials 1,2-dibromo-1-chlorotrifluoroethane with CTFE, a diluent gas containing an HFC or PFC gas is used, which makes it possible to suppress the production of isomers in the intermediate production process and improve the production yield of the intermediate.

[0077] Hereinafter, the effects of the present invention depending on the type of dilution gas and the ratio of the dilution gas to the CTFE gas in the S2 step according to scheme (10) will be explained using specific experimental examples.

[0078] 1. Preparation of 1,4-dibromo-2,3-dichlorohexafluorobutane intermediate

[0079] A 34L reactor equipped with a radical lamp was filled with 26L of a diluted solution of the reaction raw materials, 1,2-dibromo-1-chlorotrifluoroethane, and MC (methylene chloride, CHCl), in varying proportions. A vacuum was created to remove the air from the reactor, and then diluent gas and CTFE gas were supplied. The photoreaction was carried out by circulating these gases through the photoreactor under constant pressure while the lamp was operating. The product samples taken from the bottom of the reactor were analyzed by gas chromatography (GC) at hourly intervals. CTFE gas, consumed during the reaction, was continuously introduced via a regulator to maintain a constant pressure.

[0080] First, under the condition of 100 mol% CTFE, the effect of the solvent content in the 1,2-dibromo-1-chlorotrifluoroethane solution was investigated by changing the ratio of 1,2-dibromo-1-chlorotrifluoroethane to the solvent (Comparative Examples 1 to 4). The solvent used was MC (methylene chloride, CHCl), but similar results were also obtained when other solvents such as chloroform (CHCl) and carbon tetrachloride (CCl).

[0081] To investigate the effect of the ratio of dilution gas to CTFE gas, nitrogen (N2) was used as the dilution gas under the solution conditions of Comparative Example 3, and the content of CTFE gas in the total gas (total of nitrogen gas and CTFE gas) was changed in the range of 2 to 50 mol% (Examples 1 to 4).

[0082] In addition, to examine the effect of the number of lamps used for initiating light (UV) during the reaction, the number of lamps in operation was increased to 3 (Example 5) and 7 (Example 6), and then the reaction was carried out.

[0083] To investigate the effect of dilution gas containing HFC or PFC gas, the CTFE gas content was fixed at 25 mol%, and the reaction was carried out while varying the ratio of nitrogen gas to HFC or PFC gas. Although R-23 (CHF3) was used as the HFC or PFC gas, similar results could be obtained using other HFC gases such as R-32 (CH2F2), R-41 (CH3F), R-134a (CF3CH2F), and R-125 (CF3CHF2), or PFC gases such as CF4, C2F6, and C3F8.

[0084] 2. Gas chromatographic analysis results

[0085] The results of gas chromatography analysis in the comparative examples and examples are shown in Table 1. Table 1 shows the contents of the intermediate [1,4-dibromo-2,3-dichlorohexafluorobutane (Br-CF2-CFCl-CFCl-CF2-Br)], isomer [1,4-dibromo-1,3-dichlorohexafluorobutane (Br-CF2-CFCl-CF2-CFCl-Br)], high boiling point A [1,6-dibromo-2,3,5-trichlorononafluorohexane (Br-(CF2-CFCl)3-Br)], and high boiling point B [1,8-dibromo-2,3,5,7-tetrachlorododecafluoroheptane (Br-(CF2)-CFCl)4-Br)] in the sampled products, each in vol%.

[0086] [Table 1]

[0087] From Table 1, it was confirmed that the amount of high boiling point products produced was reduced when diluted with a solvent (Comparative Examples 2 to 4) compared to Comparative Example 1, in which the reaction was carried out without a solvent under conditions in which only CTFE was supplied without a dilution gas. According to the comparative examples, when the 1,2-dibromo-1-chlorotrifluoroethane solution was diluted to a concentration of 35 mol% of the solvent (MC), the production of high boiling point products was suppressed, and when the solvent content was 35 mol% or more, the production of high boiling point products was reduced, but the production of intermediates was also reduced. Therefore, when considering selectivity and reactivity, a solvent content of 35 mol% was found to be the most effective.

[0088] When the solvent content was fixed at 35 mol%, and the diluent gas concentration was examined, it was confirmed that the production of high boiling points was significantly reduced when a diluent gas was supplied, compared to Comparative Example 3, in which the reaction was carried out by supplying only CTFE without a diluent gas. Comparing Comparative Example 3 with Example 1, supplying 50 mol% of nitrogen gas as a diluent gas (50 mol% CTFE) increased the production of intermediates and significantly reduced the production of high boiling points. In Examples 2 to 4, in which the nitrogen gas was increased to 75 mol% or more (25 mol% or less CTFE), it was shown that the production of intermediates further increased and the production of high boiling points was further suppressed.

[0089] These characteristics were maintained in Examples 5 and 6, where the number of operating lamps was increased, and it was found that increasing the number of operating lamps increased the production amount of intermediates in proportion to the number of lamps.

[0090] Furthermore, it can be confirmed from Examples 7 to 10 that the production of isomers is suppressed by including HFC or PFC gas in the diluent gas. In Examples 7 to 10, the CTFE content was fixed at 25 mol%, and the HFC or PFC gas in the total diluent gas was varied within the range of 25 mol% to 75 mol%. Compared to Example 2, in which the CTFE content was also 25 mol%, it can be confirmed that the production of isomers was suppressed to some extent. This characteristic was also maintained in Example 10, in which the number of operating lamps was increased to seven.

[0091] Although the present invention has been described with reference to limited embodiments and drawings, these are merely embodiments, and it will be obvious to those skilled in the art that various modifications can be made within the scope of the technical concept of the present invention.

[0092] Therefore, the scope of protection of the present invention should be determined by the claims and their equivalents.

Claims

1. 1,4-dibromo-2,3-dichlorohexafluorobutane (Br-CF ２ -CFCl-CFCl-CF ２ -Br), comprising the steps of: 1,2-dibromo-1-chlorotrifluoroethane (Br-CF) diluted with a solvent ２ -CFCl-Br) solution was mixed with diluent gas and ２ =CFCl) gas with light (UV) initiated reaction to produce 1,4-dibromo-2,3-dichlorohexafluorobutane; The solvent is MC (Methylene Chloride, CH 2 Cl 2 ), The above-mentioned manufacturing method, wherein the dilution gas contains one or more inert gases together with one or more HFC (hydrofluorocarbon) and PFC (perfluorocarbon) gases.

2. 1,2-dibromo-1-chlorotrifluoroethane (Br-CF ２ 2. The method according to claim 1, wherein the content of the solvent in the (-CFCl-Br) solution is 90 mol % or less.

3. 2. The method according to claim 1, wherein the content of the CTFE gas in the total gas including the diluent gas and the CTFE gas is 50 mol % or less.

4. CTFE (CF ２ =CFCl) and bromine (Br ２ ) to give 1,2-dibromo-1-chlorotrifluoroethane (Br-CF ２ 2. The method of claim 1, further comprising the step of preparing a compound (CFC1-Br).

5. 1,4-dibromo-2,3-dichlorohexafluorobutane (Br-CF ２ -CFCl-CFCl-CF ２ -Br) intermediate to produce hexafluoro-1,3-butadiene (C ４ F ６ ), a method for producing 1,2-dibromo-1-chlorotrifluoroethane (Br-CF) diluted with a solvent ２ -CFCl-Br) solution was mixed with diluent gas and ２ a photoreaction step in which 1,4-dibromo-2,3-dichlorohexafluorobutane is produced by reacting 1,4-dibromo-2,3-dichlorohexafluorobutane with 1,4-dibromo-2,3-dichlorohexafluorobutane (=CFCl) gas with light (UV) initiated reaction; a dehalogenation step of removing halogen atoms other than fluorine atoms from the produced 1,4-dibromo-2,3-dichlorohexafluorobutane; The solvent is MC (Methylene Chloride, CH 2 Cl 2 ), The dilution gas contains one or more inert gases together with one or more HFC (hydrofluorocarbon) and PFC (perfluorocarbon) gases.

6. 6. The method of claim 5, wherein the dehalogenation step is carried out in the presence of zinc (Zn) and isopropyl alcohol.

7. Before the photoreaction step, CTFE (CF ２ =CFCl) and bromine (Br ２ ) to give 1,2-dibromo-1-chlorotrifluoroethane (Br-CF ２ 6. The method of claim 5, further comprising the step of preparing a compound selected from the group consisting of CFCl-CFCl-Br.

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