Method for producing diiodide, and composition containing diiodide

Abstract

The present invention provides a method for producing a diiodide by mixing: a crude composition containing at least one component selected from the group consisting of a diiodide represented by the formula I(CF2CF2)nI (in the formula, n is an integer of 1 or more), an ether represented by the formula I(CF2CF2)mOR1 (in the formula, m is an integer of 1 or more, and R1 is an organic group) and an ester represented by the formula ICF2COOR2 (in the formula, R2 is an organic group); a hydroxide represented by the formula M(OH)p (in the formula, p is 1 or 2, and M is an alkali metal or an alkaline earth metal); and an aqueous solution that contains water. As a result of the foregoing, a mixture is prepared. The mixture is separated into a phase that contains the diiodide and a phase that contains water, and the phase that contains the diiodide is recovered.

Description

Method for producing diiodide and composition containing diiodide

[0001] The present disclosure relates to methods for making diiodides and compositions containing diiodides.

[0002] Patent Document 1 discloses a method for producing a compound represented by the following formula I(CF) by reacting 1,2-diiodotetrafluoroethylene with tetrafluoroethylene in the presence of a catalytic amount of a free radical catalyst. ２ CF ２ ) ｎ A process for preparing alpha-omega-diiodinated fluoroalkanes is described which comprises forming a telomeric product of formula I, where n is 2 to 10, and absorbing the telomeric product from the reaction mixture.

[0003] Japanese Patent Application Publication No. 47-2573

[0004] An object of the present disclosure is to provide a method for producing high-purity diiodide.

[0005] According to the present disclosure, there is provided a method for producing a diiodide, comprising the steps of: ２ CF ２ ) ｎ I (wherein n is an integer of 1 or more), and diiodides represented by the general formula (1-2): I(CF ２ CF ２ ) ｍ OR １ (wherein m is an integer of 1 or more, R １ represents an organic group), and an ether represented by the general formula (1-3): ICF ２ COOR ２ (In the formula, R ２ a crude composition containing at least one ester selected from the group consisting of esters represented by the general formula (2-1): M(OH) ｐ (wherein p is 1 or 2, and M is an alkali metal or alkaline earth metal) and an aqueous solution containing water, to prepare a mixture; separating the mixture into a phase containing the diiodide and a phase containing water; and recovering the phase containing the diiodide.

[0006] According to the present disclosure, a method for producing a high-purity diiodide can be provided.

[0007] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0008] Patent Document 1 proposes a method for producing alpha-omega-diiodinated fluoroalkanes by forming a telomeric product through a telomerization reaction using 1,2-diiodotetrafluoroethylene as a telogen and tetrafluoroethylene as a taxogen, and also describes that the telomers can be separated, if desired, by fractional distillation of the telomer mixture under reduced pressure.

[0009] However, when an attempt is made to separate and recover the telomers (diiodides) by fractional distillation of the telomeric products produced by such conventional production methods, there is a problem in that each telomer cannot be recovered in sufficient yield.

[0010] Therefore, we have intensively investigated the cause of this problem and found that the telomerization reaction produces ethers or esters in addition to diiodides, and that the ethers or esters in the reaction product prevent the diiodides from being separated by fractional distillation, which is the reason why the yield does not improve. Furthermore, we have intensively investigated means for solving this problem and found a means for removing the ethers or esters produced by the telomerization reaction from the reaction product, and also found that by fractional distillation of the reaction product from which the ethers or esters have been removed, diiodides with different carbon numbers can be separated and each diiodide can be recovered in high yield.

[0011] That is, according to the present disclosure, there is provided a method for producing a diiodide, comprising the steps of: ２ CF ２ ) ｎ I (wherein n is an integer of 1 or more) and a diiodide represented by the general formula (1-2): I(CF ２ CF２ ) ｍ OR １ (wherein m is an integer of 1 or more, R １ represents an organic group), and an ether represented by the general formula (1-3): ICF ２ COOR ２ (In the formula, R ２ and (2-1): M(OH) ｐ (wherein p is 1 or 2, and M is an alkali metal or alkaline earth metal) and an aqueous solution containing water, to prepare a mixture; separating the mixture into a phase containing the diiodide and a phase containing water; and recovering the phase containing the diiodide.

[0012] According to the production method of the present disclosure, the ether or ester in the crude composition containing the diiodide can be separated from the crude composition, and a composition containing the diiodide at a high purity can be recovered in a high yield. Furthermore, by distilling the composition containing the diiodide at a high purity by a method such as fractional distillation or steam distillation, the diiodide having the target n number can be separated and recovered in a high yield.

[0013] The manufacturing method of the present disclosure will be described in further detail below.

[0014] The present disclosure relates to a method for producing a composition containing a diiodide at high purity. The production method of the present disclosure includes mixing a crude composition containing a diiodide and at least one selected from the group consisting of an ether and an ester with an aqueous solution containing a hydroxide and water to prepare a mixture, separating the resulting mixture into two phases, and recovering the phase containing the diiodide at high purity.

[0015] In one embodiment, the crude composition is prepared by a telomerization reaction using 1,2-diiodotetrafluoroethylene as a telogen and tetrafluoroethylene as a taxogen. This telomerization reaction produces a crude composition containing, in addition to the diiodide represented by general formula (1-1), an ether represented by general formula (1-2) or an ester represented by general formula (1-3). When the crude composition is mixed with an aqueous solution containing a hydroxide, the ether and ester in the crude composition react with the hydroxide and are decomposed. Meanwhile, the diiodide remains in the mixture without being decomposed. When the resulting mixture is allowed to stand, it separates into two phases: a phase containing the diiodide as a major component, and a phase containing water or hydroxide as a major component. By recovering the phase containing the diiodide as a major component, a composition containing the diiodide at a high purity can be produced.

[0016] That is, general formula (1-1): I(CF ２ CF ２ ) ｎ I (wherein n is an integer of 1 or more) and a diiodide represented by the general formula (1-2): I(CF ２ CF ２ ) ｍ OR １ (wherein m is an integer of 1 or more, R １ represents an organic group), and an ether represented by the general formula (1-3): ICF ２ COOR ２ (In the formula, R ２ and is an organic group), and a composition containing: is an important raw material for producing a composition containing a diiodide at high purity.

[0017] The diiodide contained in the crude composition is represented by the general formula (1-1): I(CF ２ CF ２ ) ｎI (wherein n is an integer of 1 or more). n may be an integer of 1 to 20, an integer of 1 to 10, or an integer of 1 to 8. In one embodiment, the crude composition contains at least a diiodide represented by general formula (1-1) in which n is an integer of 1 to 8.

[0018] In one embodiment, the crude composition contains a diiodide represented by general formula (1-1) in which n is an integer of 1 to 8, and also contains a diiodide represented by general formula (1-1) in which n is an integer of 9 or more.

[0019] The crude composition only needs to contain at least a diiodide represented by general formula (1-1), and may contain, for example, only one diiodide represented by general formula (1-1) where n is any numerical value. However, the crude composition preferably contains at least two or more diiodides represented by general formula (1-1) where n is different numerical values. That is, the crude composition is preferably a diiodide mixture containing two or more diiodides represented by general formula (1-1) where n is different numerical values.

[0020] In one embodiment, the crude composition contains, as the diiodide, I(CF ２ CF ２ ) I, I (CF ２ CF ２ ) ２ I and I(CF ２ CF ２ ) ３ In one embodiment, the crude composition contains at least eight diiodides represented by general formula (1-1), where n is 1 to 8.

[0021] The crude composition contains, in addition to the diiodide, a compound of the general formula (1-2): I(CF ２ CF ２ ) ｍ OR １ (wherein m is an integer of 1 or more, R １ represents an organic group), and an ether represented by the general formula (1-3): ICF ２ COOR ２ (In the formula, R ２is an organic group).

[0022] The crude composition may be a crude composition containing a diiodide represented by general formula (1-1) and an ether represented by general formula (1-2), a crude composition containing a diiodide represented by general formula (1-1) and an ester represented by general formula (1-3), or a crude composition containing a diiodide represented by general formula (1-1), an ether represented by general formula (1-2), and an ester represented by general formula (1-3).

[0023] The total content of the ether represented by general formula (1-2) and the ester represented by general formula (1-3) in the crude composition is preferably 20.0 mass% or less, more preferably 10.0 mass% or less, relative to the mass of the crude composition. The lower limit is not particularly limited, but may be 1.0 mass% or more. The total content of the ether and the ester in the crude composition can be measured by gas chromatography analysis.

[0024] The content of the diiodide represented by general formula (1-1) in the crude composition is preferably 80.0 mass% or more, more preferably 90.0 mass% or more, and preferably 99.0 mass% or less, based on the mass of the crude composition. The content of the diiodide in the crude composition can be measured by gas chromatography analysis.

[0025] In general formula (1-2), m is an integer of 1 or greater. m may be an integer of 2 or greater, an integer of 20 or less, an integer of 10 or less, an integer of 8 or less, or an integer of 5 or less. In one embodiment, the crude composition contains at least an ether represented by general formula (1-2) in which m is an integer of 2 to 5. In one embodiment, the crude composition contains an ether represented by general formula (1-2) in which m is an integer of 2 to 5, and also contains a diiodide represented by general formula (1-2) in which m is an integer of 6 or greater.

[0026] In the general formula (1-2), R １ is an organic group. １is preferably a hydrocarbon group, more preferably an alkyl group or an aryl group. The number of carbon atoms in the hydrocarbon group and the alkyl group is preferably 1 to 30, more preferably 1 to 15, and even more preferably 1 to 4. The aryl group is preferably a phenyl group. R １ Examples of the R include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, and a phenyl group. When the crude composition is prepared by a telomerization reaction using an organic peroxide, R １ is formed by a hydrocarbon group derived from an organic peroxide.

[0027] In general formula (1-3), R ２ is an organic group. ２ is preferably a hydrocarbon group, more preferably an alkyl group or an aryl group. The number of carbon atoms in the hydrocarbon group and the alkyl group is preferably 1 to 30, more preferably 1 to 15, and even more preferably 1 to 4. The aryl group is preferably a phenyl group. R ２ Examples of the R include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, and a phenyl group. When the crude composition is prepared by a telomerization reaction using an organic peroxide, R ２ is formed by a hydrocarbon group derived from an organic peroxide.

[0028] R in general formula (1-2) １ and R in general formula (1-3) ２ In one embodiment, R in general formula (1-2) １ and R in general formula (1-3) ２ is the same as

[0029] The aqueous solution to be mixed with the crude composition is a compound represented by the general formula (2-1): M(OH) ｐ (wherein p is 1 or 2, and M is an alkali metal or alkaline earth metal) and water.

[0030] In the general formula (2-1), M is an alkali metal or alkaline earth metal, and is preferably at least one selected from the group consisting of Li, K, and Na, with K being more preferred.

[0031] The hydroxide represented by the general formula (2-1) is preferably at least one selected from the group consisting of LiOH, KOH and NaOH, and more preferably KOH.

[0032] The content of the hydroxide in the aqueous solution is preferably 1% by mass to the saturated solubility concentration of each hydroxide at 20° C. based on the aqueous solution.

[0033] In the production method of the present disclosure, a crude composition is mixed with an aqueous solution to prepare a mixture. The mixing ratio of the crude composition to the aqueous solution (crude composition:aqueous solution) is preferably 1:99 to 99:1, more preferably 10:90 to 95:5, and even more preferably 20:80 to 90:10.

[0034] The mixture can be prepared, for example, by adding the aqueous solution to the crude composition all at once, or stepwise or continuously. Mixing can be performed with stirring. A stirrer or stirring blade may be used for stirring. Alternatively, the crude composition and the aqueous solution may be continuously circulated and mixed using a static mixer, a packed column, or the like. A phase transfer catalyst or an emulsifier may be added to the system to promote mixing of the crude composition and the aqueous solution. Since the mixture may generate heat when the aqueous solution is added to the crude composition, the aqueous solution can be added stepwise or continuously to the crude composition so as to maintain the temperature of the mixture within the range of 40 to 100°C, for example.

[0035] The crude composition and the aqueous solution can be mixed, for example, at a temperature in the range of 40 to 150°C. If the temperature is too low, the crude composition, the aqueous solution, or the mixture may be heated to adjust the temperature to the above range. If the temperature when mixing the crude composition and the aqueous solution is too high, the diiodide may volatilize or decompose, resulting in a reduced yield. Therefore, it is preferable to determine the mixing temperature taking into account the boiling point of the diiodide. When using a crude composition obtained by distilling a reaction product prepared by a telomerization reaction, the mixing temperature is preferably 50 to 90°C. When using a reaction product prepared by a telomerization reaction as the crude composition, the mixing temperature is preferably 50 to 150°C.

[0036] After mixing the crude composition with the aqueous solution, the resulting mixture may be left to stand for 10 minutes to 24 hours while maintaining the temperature of the resulting mixture within the above temperature range.

[0037] Next, the mixture obtained by mixing the crude composition with the aqueous solution is allowed to stand to separate into two phases: a phase containing the diiodide as the main component and a phase containing water or hydroxide as the main component. When the resulting mixture is allowed to stand, it usually separates into two phases: a lower phase containing the diiodide as the main component and an upper phase containing water or hydroxide as the main component. By recovering the phase containing the diiodide as the main component, a composition containing the diiodide at high purity can be produced. In the present disclosure, the term "main component" means a component that accounts for more than 50% by mass of the phase.

[0038] The total content of the ether represented by general formula (1-2) and the ester represented by general formula (1-3) in the composition containing the diiodide obtained by the production method of the present disclosure is preferably 500 ppm by mass or less, and more preferably 100 ppm by mass or less, relative to the mass of the composition. The lower limit is not particularly limited, but may be 0.1 ppm by mass or more, or may be 1.0 ppm by mass or more. The total content of the ether and ester in the composition can be measured by gas chromatography analysis.

[0039] The content of the diiodide represented by general formula (1-1) in the composition is preferably more than 99.0 mass %, and more preferably 99.9 mass % or more, based on the mass of the composition. The content of the diiodide in the composition can be measured by gas chromatography analysis.

[0040] In the manufacturing method of the present disclosure, the crude composition may be prepared by a telomerization reaction using 1,2-diiodotetrafluoroethylene as a telogen and tetrafluoroethylene as a taxogen.

[0041] In the production method of the present disclosure, the reaction product produced by the telomerization reaction may be used as the crude composition, or a fraction or residue obtained after distilling the reaction product produced by the telomerization reaction may be used as the crude composition. The distillation of the reaction product produced by the telomerization reaction may be carried out by known methods such as fractional distillation or steam distillation.

[0042] The 1,2-diiodotetrafluoroethylene used in the telomerization reaction can be produced by known production methods such as the production method described in Japanese Patent Publication No. 43-11884 and the production method described in US Pat. No. 2,424,667.

[0043] The telomerization reaction can be carried out using an organic peroxide. In the telomerization reaction carried out in the presence of an organic peroxide, the organic peroxide decomposes to generate radicals, which then abstract the iodine atom from 1,2-diiodotetrafluoroethylene to generate new alkyl radicals, and a reaction of tetrafluoroethylene adding to the alkyl radicals proceeds.

[0044] Examples of organic peroxides include dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and diacyl peroxides such as benzoyl peroxide.

[0045] The amount of tetrafluoroethylene used is preferably 0.01 to 100 moles per mole of 1,2-diiodotetrafluoroethylene.

[0046] The amount of the organic peroxide used is preferably 0.01 to 2 moles per mole of 1,2-diiodotetrafluoroethylene.

[0047] The temperature for the reaction of 1,2-diiodotetrafluoroethylene with tetrafluoroethylene can be appropriately selected, but is preferably −78 to 200° C. Furthermore, the temperature for the reaction of 1,2-diiodotetrafluoroethylene with tetrafluoroethylene is preferably equal to or higher than the temperature corresponding to the 10-hour half-life of the organic peroxide, and is preferably lower than the decomposition temperatures of the substrate and the product.

[0048] The pressure for the reaction of 1,2-diiodotetrafluoroethylene with tetrafluoroethylene can be selected as appropriate, but is preferably 0 to 5.0 MPaG. As practiced in Japanese Patent No. 6545187 and JP-A-53-144507, a diluent gas such as carbon dioxide or nitrogen may be allowed to coexist with tetrafluoroethylene in the gas phase of the reaction. The time for the reaction of 1,2-diiodotetrafluoroethylene with tetrafluoroethylene can be selected as appropriate, but is preferably 0.1 to 96 hours.

[0049] In the production method of the present disclosure, after recovering the phase containing the diiodide, the phase may be distilled. The recovered phase containing the diiodide is a composition containing the diiodide at a high purity, from which the ether represented by general formula (1-2) and the ester represented by general formula (1-3) have been removed or reduced. By distilling such a composition, the diiodide having the target n number can be separated and recovered in a higher yield than when a composition containing at least either the ether represented by general formula (1-2) or the ester represented by general formula (1-3) is distilled.

[0050] The distillation can be carried out by known methods such as fractional distillation and steam distillation. Since diiodide has a high boiling point and easily undergoes thermal decomposition, it is preferable to distill the phase containing the diiodide under reduced pressure. The pressure during distillation is preferably 0 MPaG or less, more preferably -0.09 MPaG or less. By distillation, I(CF ２ CF ２ )I as a major component, I(CF ２ CF ２ ) ２ Fractions containing I as a major component, I(CF ２ CF ２ ) ３ It is possible to recover a fraction containing I as a main component.

[0051] In one embodiment, I(CF) is removed from the diiodide-containing phase by distillation. ２ CF ２ ) ３ In one embodiment, the fraction containing I(CF) as the main component is recovered from the diiodide-containing phase by distillation. ２ CF ２ )I as a major component, I(CF ２ CF ２ ) ２ A fraction containing I as a main component, and I(CF ２ CF ２ ) ３ The fractions containing I as the main component are each recovered.

[0052] In one embodiment of the manufacturing method of the present disclosure, I(CF) is produced by a telomerization reaction using 1,2-diiodotetrafluoroethylene as a telogen and tetrafluoroethylene as a taxogen. ２ CF ２ ) I, I (CF ２ CF ２ ) ２ I and I(CF ２ CF ２ ) ３a crude composition containing at least I and at least one selected from the group consisting of an ether represented by general formula (1-2) and an ester represented by general formula (1-3); and distilling the crude composition to obtain I(CF ２ CF ２ The fraction containing I as a main component is recovered, and the residue obtained by the above distillation (I(CF) ２ CF ２ ) the residue remaining after recovery of the fraction containing I as the main component) is distilled to obtain I(CF ２ CF ２ ) ２ The fraction containing I as the main component was recovered, and the residue (I(CF) ２ CF ２ ) ２ a crude composition (residue remaining after recovering a fraction containing I(CF) as a main component) is used, and the residue is mixed with an aqueous solution containing a hydroxide represented by general formula (2-1) and water to prepare a mixture; the resulting mixture is separated into a phase containing the diiodide and a phase containing water, and the phase containing the diiodide is recovered; and the phase containing the diiodide is distilled to obtain I(CF) ２ CF ２ ) ３ The fraction containing I as the main component is recovered.

[0053] According to the production method of this embodiment, it is possible to obtain I(CF) with high purity and in high yield. ２ CF ２ ) ３ I can be recovered.

[0054] In one embodiment of the manufacturing method of the present disclosure, I(CF) is produced by a telomerization reaction using 1,2-diiodotetrafluoroethylene as a telogen and tetrafluoroethylene as a taxogen. ２ CF ２ ) I, I (CF ２ CF ２ ) ２ I and I(CF ２ CF ２ ) ３a crude composition containing at least I and at least one selected from the group consisting of an ether represented by general formula (1-2) and an ester represented by general formula (1-3); a mixture is prepared by mixing the crude composition with an aqueous solution containing a hydroxide represented by general formula (2-1) and water; the resulting mixture is separated into a phase containing a diiodide and a phase containing water, and the phase containing the diiodide is recovered; and the phase containing the diiodide is distilled to obtain I(CF ２ CF ２ The fraction containing I as a main component is recovered, and the residue obtained by the above distillation (I(CF) ２ CF ２ ) the residue remaining after recovery of the fraction containing I as the main component) is distilled to obtain I(CF ２ CF ２ ) ２ The fraction containing I as the main component was recovered, and the residue (I(CF) ２ CF ２ ) ２ The residue remaining after recovering the fraction containing I as the main component is distilled to obtain I(CF ２ CF ２ ) ３ The fraction containing I as the main component is recovered.

[0055] According to the production method of this embodiment, it is possible to obtain I(CF) with high purity and in high yield. ２ CF ２ ) I, I (CF ２ CF ２ ) ２ I and I(CF ２ CF ２ ) ３ I can be recovered individually.

[0056] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0057] <1> According to a first aspect of the present disclosure, there is provided a method for producing a diiodide, the method comprising: ２ CF２ ) ｎ I (wherein n is an integer of 1 or more), and diiodides represented by the general formula (1-2): I(CF ２ CF ２ ) ｍ OR １ (wherein m is an integer of 1 or more, R １ represents an organic group), and an ether represented by the general formula (1-3): ICF ２ COOR ２ (In the formula, R ２ a crude composition containing at least one ester selected from the group consisting of esters represented by the general formula (2-1): M(OH) ｐ (wherein p is 1 or 2, and M is an alkali metal or alkaline earth metal) and an aqueous solution containing water to prepare a mixture, separating the mixture into a phase containing the diiodide and a phase containing water, and recovering the phase containing the diiodide. <2> According to a second aspect of the present disclosure, there is provided a production method according to the first aspect, wherein the phase containing the diiodide is recovered and then distilled. <3> According to a third aspect of the present disclosure, ２ CF ２ ) I, I (CF ２ CF ２ ) ２ I and I(CF ２ CF ２ ) ３ <4> According to a fourth aspect of the present disclosure, there is provided a production method according to the first or second aspect, which comprises recovering a phase containing a diiodide, and then distilling the phase to obtain I(CF ２ CF ２ ) ３<5> According to a fifth aspect of the present disclosure, there is provided a production method according to any one of the first to fourth aspects, in which the crude composition is prepared by a telomerization reaction using 1,2-diiodotetrafluoroethylene as a telogen and tetrafluoroethylene as a taxogen. <6> According to a sixth aspect of the present disclosure, there is provided a production method according to any one of the first to fourth aspects, in which the crude composition is prepared by preparing a reaction product by a telomerization reaction using 1,2-diiodotetrafluoroethylene as a telogen and tetrafluoroethylene as a taxogen, and distilling the reaction product. <7> According to a seventh aspect of the present disclosure, there is provided a production method according to the fifth or sixth aspect, in which the telomerization reaction is carried out in the presence of an organic peroxide. <8> According to an eighth aspect of the present disclosure, there is provided a production method according to the fifth or sixth aspect, in which the diiodide is a compound represented by the general formula: I(CF ２ CF ２ ) ｎ I (wherein n is an integer of 1 to 8), and the ether is a diiodide represented by the general formula: I(CF ２ CF ２ ) ｍ OR １ (In the formula, R １ is an alkyl group having 1 to 4 carbon atoms, and m is an integer of 2 to 5), and the ester is an ether represented by the general formula: ICF ２ COOR ２ (In the formula, R ２is an alkyl group having 1 to 4 carbon atoms), the content of the diiodide in the crude composition is preferably 80.0 to 99.0 mass% relative to the mass of the crude composition, the total content of the ether and the ester in the crude composition is 1.0 to 20.0 mass% relative to the mass of the crude composition, the hydroxide is at least one selected from the group consisting of LiOH, KOH, and NaOH, the content of the hydroxide in the aqueous solution is 1 mass% or more relative to the aqueous solution and not more than the saturated solubility concentration of the hydroxide at 20°C, the mass ratio of the crude composition to the aqueous solution (crude composition:aqueous solution) is 20:80 to 90:10, and the temperature when mixing the crude composition and the aqueous solution is 40 to 150°C. <9> A production method according to any of the first to seventh aspects is provided. ２ CF ２ ) ｎ I (wherein n is an integer of 1 or more), and diiodides represented by the general formula (1-2): I(CF ２ CF ２ ) ｍ OR １ (wherein m is an integer of 1 or more, R １ represents an organic group), and an ether represented by the general formula (1-3): ICF ２ COOR ２ (In the formula, R ２ and an ester represented by the general formula: I(CF), wherein the total content of the ether and the ester is 500 ppm by mass or less relative to the mass of the composition. <10> According to a tenth aspect of the present disclosure, there is provided a composition comprising: a diiodide represented by the general formula: I(CF ２ CF ２ ) ｎ I (wherein n is an integer of 1 to 8), and the ether is a diiodide represented by the general formula: I(CF ２ CF ２ ) ｍ OR １ (In the formula, R １is an alkyl group having 1 to 4 carbon atoms, and m is an integer of 2 to 5), and the ester is an ether represented by the general formula: ICF ２ COOR ２ (In the formula, R ２ and (wherein the alkyl group is an alkyl group having 1 to 4 carbon atoms), and the content of the diiodide is more than 99.0 mass % relative to the mass of the composition.

[0058] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0059] Synthesis Example 1 ICF was placed in a 200 ml SUS316 autoclave equipped with a stirring blade. ２ CF ２ The reactor was cooled to -15°C and evacuated, and then tetrafluoroethylene (TFE) (54 g) was charged from the gas phase. ２ CF ２ The temperature was raised to 55° C. to react I. The reaction pressure decreased as TFE was consumed in the reaction (the reaction pressure was 2.8 MPaG at the start of the reaction, but decreased to 1.8 MPaG after 14 hours of reaction).

[0060] After 14 hours of reaction, the reactor was allowed to cool until the temperature reached room temperature, after which the residual pressure was released to atmospheric pressure. 249 g of the crude reaction product remaining in the reactor was recovered, and the composition of the resulting telomer mixture (crude reaction product) was confirmed by gas chromatography. The results are shown in Table 1.

[0061] Gas chromatography was carried out under the following conditions: Measurement device: Shimadzu GC-2014 Column: Silicone SE-30 (15%) Column temperature conditions: 50°C, 5 min, 10°C / min, 250°C, 5 min Vaporizer temperature: 250°C Detector temperature: 250°C Detector: TCD Carrier gas type: Helium Sample injection amount: 1 μl

[0062] Example 1 The procedure for decomposing and removing ethers and esters by adding an aqueous KOH solution to the telomer mixture obtained in Synthesis Example 1 is shown below.

[0063] A 100 ml three-necked flask equipped with a stirrer and a condenser was charged with 153 g of the telomer mixture obtained in Synthesis Example 1. After heating to 50°C, 35 g of a 48% by mass aqueous solution of KOH was charged and reacted while adjusting the amount charged so that the temperature inside the vessel would be 50 to 60°C. After the KOH charging was completed, the temperature was maintained at 50 to 60°C and the reaction was continued for another 2 hours.

[0064] The reaction product after the reaction was obtained as a mixture consisting of two phases: a KOH aqueous solution phase and a telomer phase. The results of analyzing the lower phase (telomer phase) using gas chromatography are shown in Table 1. It was confirmed that the ether and ester had disappeared. Upon liquid-liquid separation from the reaction mixture, 142 g of the telomer phase was recovered. Considering that the ether and ester had been decomposed and removed, this amount was almost quantitative.

[0065] In Tables 1 and 2, the diiodides, ethers, and esters are compounds represented by the following chemical formulas: Diiodide: I(CF ２ CF ２ ) ｎ I (wherein n is an integer as shown in Table 1) ether: I(CF ２ CF ２ ) ｍ OCH (CH ３ ) ２ (wherein m is an integer as shown in Table 1) Ester: ICF ２ COOCH (CH ３ ) ２

[0066]

[0067] Example 2 Example 2 shows an example of decomposing and removing ethers in the residue produced by fractional distillation of the reaction product obtained by the telomerization reaction.

[0068] The telomer mixture obtained in Synthesis Example 1 was subjected to fractional distillation to separate and recover the diiodide (n=1) and the diiodide (n=2), and also to recover a residue. The residue was analyzed using gas chromatography, and the results are shown in Table 2.

[0069] 125 g of the residue was charged into a 100 ml three-necked flask equipped with a stirrer and a condenser. After heating, the reactor reached 50°C, and charging of a 48% by mass aqueous solution of KOH was initiated. The reaction occurred with the addition of KOH, and heat generation became evident. The amount of 48% by mass aqueous solution of KOH charged was adjusted so that the temperature inside the reactor was maintained at 90 to 100°C. 34 g of KOH was charged over 2 hours. After the completion of charging of KOH, the temperature was maintained at 90 to 100°C, and the reaction was continued for another 3 hours.

[0070] The reaction product after the reaction was separated into a KOH aqueous solution phase and a telomer phase. The telomer phase was analyzed by gas chromatography, and the results are shown in Table 2.

[0071]

[0072] Comparative Example 1 The telomer mixture obtained in Synthesis Example 1 was distilled under reduced pressure at 4.5 kPa using a 15-plate glass Oldershaw distillation apparatus according to a conventional method. The results are shown below. Isolation yield of diiodide (n=1) (purity 90% or more): 85% Isolation yield of diiodide (n=2) (purity 90% or more): 52%

[0073] Example 3: The telomer phase obtained in Example 1 was distilled under reduced pressure at 4.5 kPa using a 15-plate glass Oldershaw distillation apparatus according to a conventional method. The results are shown below. Isolation yield of diiodide (n=1) (purity 90% or more): 89% Isolation yield of diiodide (n=2) (purity 90% or more): 94%

[0074] From the results of Comparative Example 1 and Example 3, it was confirmed that the recovery yield of telomer (diiodide) was improved by neutralizing and removing impurities in the raw material.

Claims

1. A method for producing a diiodide, comprising the steps of: General formula (1-1): I(CF ２ CF ２ ) ｎ I (wherein n is an integer of 1 or more), and General formula (1-2): I(CF ２ CF ２ ) ｍ OR １ (wherein m is an integer of 1 or more, R １ is an organic group), and General formula (1-3): ICF ２ COOR ２ (In the formula, R ２ is an organic group) At least one selected from the group consisting of a crude composition comprising: General formula (2-1): M(OH) ｐ (wherein p is 1 or 2, and M is an alkali metal or an alkaline earth metal), and an aqueous solution containing water; preparing a mixture by mixing The mixture is separated into a phase containing the diiodide and a phase containing water, and the phase containing the diiodide is recovered. Manufacturing method.

2. 2. The process of claim 1, wherein after the diiodide-containing phase is recovered, said phase is distilled.

3. The crude composition is I(CF ２ CF ２ ) I, I (CF ２ CF ２ ) ２ I and I(CF ２ CF ２ ) ３ The method according to claim 1 or 2, wherein the compound contains at least I.

4. After recovering the phase containing the diiodide, the phase was distilled to obtain I(CF ２ CF ２ ) ３ 4. The method according to claim 3, wherein a fraction containing I as a main component is recovered.

5. The method of claim 1, wherein the crude composition is prepared by a telomerization reaction using 1,2-diiodotetrafluoroethane as a telogen and tetrafluoroethylene as a taxogen.

6. A manufacturing method described in claim 1 or 2, in which a reaction product is prepared by a telomerization reaction using 1,2-diiodotetrafluoroethane as a telogen and tetrafluoroethylene as a taxogen, and the crude composition is prepared by distilling the reaction product.

7. 6. The method according to claim 5, wherein the telomerization reaction is carried out in the presence of an organic peroxide.

8. The diiodide is General formula: I(CF ２ CF ２ ) ｎ I (wherein n is an integer from 1 to 8) It is a diiodide represented by The ether is General formula: I(CF ２ CF ２ ) ｍ OR １ (In the formula, R １ is an alkyl group having 1 to 4 carbon atoms, and m is an integer from 2 to 5. is an ether represented by The ester is General formula: ICF ２ COOR ２ (In the formula, R ２ represents an alkyl group having 1 to 4 carbon atoms) is an ester represented by the content of the diiodide in the crude composition is 80.0 to 99.0% by mass relative to the mass of the crude composition; the total content of the ether and the ester in the crude composition is 1.0 to 20.0% by mass, based on the mass of the crude composition; the hydroxide is at least one selected from the group consisting of LiOH, KOH, and NaOH; the content of the hydroxide in the aqueous solution is 1% by mass or more and is equal to or less than the saturated solubility concentration of the hydroxide at 20°C, the mass ratio of the crude composition to the aqueous solution (crude composition:aqueous solution) is 20:80 to 90:10; The temperature when the crude composition and the aqueous solution are mixed is 40 to 150°C. The method according to claim 1 or 2.

9. General formula (1-1): I(CF ２ CF ２ ) ｎ I (wherein n is an integer of 1 or more), and General formula (1-2): I(CF ２ CF ２ ) ｍ OR １ (wherein m is an integer of 1 or more, R １ is an organic group), and General formula (1-3): ICF ２ COOR ２ (In the formula, R ２ is an organic group) Contains at least one selected from the group consisting of A composition, wherein the total content of the ether and the ester is 500 ppm by mass or less, based on the mass of the composition.

10. The diiodide is General formula: I(CF ２ CF ２ ) ｎ I (wherein n is an integer from 1 to 8) It is a diiodide represented by The ether is General formula: I(CF ２ CF ２ ) ｍ OR １ (In the formula, R １ is an alkyl group having 1 to 4 carbon atoms, and m is an integer from 2 to 5. is an ether represented by The ester is General formula: ICF ２ COOR ２ (In the formula, R ２ represents an alkyl group having 1 to 4 carbon atoms) is an ester represented by The composition according to claim 9, wherein the content of the diiodide is greater than 99.0% by mass, based on the mass of the composition.