Production method of 1,4-diiodooctafluorobutane product

Abstract

To provide a highly efficient production method of 1,4-diiodooctafluorobutane product with suppressed discoloration.SOLUTION: A decolorizing step to mix a crude product containing 1,4-diiodooctafluorobutane with an aqueous solution of a reducing agent in a first agitation tank so as to obtain a decolorized first mixture, a first separation step to separate the first mixture into a heavy phase containing 1,4-diiodooctafluorobutane and a light phase containing water in a first separation tank, a cleaning step to mix the heavy phase with water in a second agitation tank so as to obtain a second mixture containing a cleaned heavy phase, and a second separation step to separate the second mixture into the heavy phase containing 1,4-diiodooctafluorobutane and the light phase containing water in a second separation tank so as to obtain the 1,4-diiodooctafluorobutane product, are continuously carried out.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing 1,4-diiodooctafluorobutane products. Relates to.

Background Art

[0002] 1,4-Diiodooctafluorobutane is a bifunctional fluorocarbon compound having iodine groups as reactive sites at both ends, and is a chain transfer agent used in the synthesis of fluorine-containing polymer materials such as fluororubber (FKM), or is useful as an additive to fluorine-containing polymer materials. 1,4-Diiodooctafluorobutane can be synthesized by subjecting 1,2-diiodotetrafluoroethane to a telomerization reaction in the presence of iodine (I2). In addition to the target product 1,4-diiodooctafluorobutane, the reaction product contains I2 added initially or generated by the telomerization reaction, and by-products such as the trimer 1,6-diiodododecafluorohexane. Tetrafluoroethylene is added to the reaction product and reacted with I2 to convert it to 1,2-diiodotetrafluoroethane. In the subsequent rectification step, 1,4-diiodooctafluorobutane as a product, 1,2-diiodotetrafluoroethylene, and by-products are separated. I2 mixed in the 1,4-diiodooctafluorobutane product is removed by reacting it with a reducing agent. The separated 1,2-diiodotetrafluoroethylene is reused in the telomerization reaction.

[0003] Patent Document 1 (Japanese Patent Laid-Open No. 53-144507) describes that when producing 1,4-diiodooctafluorobutane from 1,2-diiodotetrafluoroethane by a deiodination reaction, iodine (I2) is added to the reaction system in advance and heated.

[0004] Patent Document 2 (International Publication No. 2016 / 138253) and Patent Document 3 (Specification of Chinese Patent Application Publication No. 1752059) describe that I2 in a 1,4-diiodooctafluorobutane product is washed and removed using a saturated aqueous solution of sodium bisulfite (Patent Document 2) or a saturated aqueous solution of sodium thiosulfate (Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] Even trace amounts of I2 color the 1,4-diiodooctafluorobutane product. Depending on the use of the 1,4-diiodooctafluorobutane product, coloring may not be desirable.

[0007] An object of the present invention is to provide a method for efficiently producing a 1,4-diiodooctafluorobutane product with suppressed coloring.

Means for Solving the Problems

[0008] The present inventors have found that when decolorizing a crude product containing 1,4-diiodooctafluorobutane with an aqueous solution of a reducing agent, by continuously performing a decolorization step, a washing step, and a liquid-liquid separation step, a 1,4-diiodooctafluorobutane product with suppressed coloring can be efficiently produced, and thus have completed the present invention.

[0009] This application includes the following aspects. [Aspect 1] In a first stirring tank, a crude product containing 1,4-diiodooctafluorobutane is mixed with an aqueous solution of a reducing agent to obtain a decolorized first mixture in a decolorization step; In a first separation tank, the first mixture is separated into a heavy phase containing 1,4-diiodooctafluorobutane and a light phase containing water in a first separation step; In a second stirring tank, the heavy phase is mixed with water to obtain a second mixture containing a washed heavy phase in a washing step; In a second separation tank, the second mixture is separated into a heavy phase containing 1,4-diiodooctafluorobutane and a light phase containing water to obtain a 1,4-diiodooctafluorobutane product in a second separation step; A method for producing a 1,4-diiodooctafluorobutane product, including the decolorization step, the first separation step, the washing step, and the second separation step, and continuously performing the decolorization step, the first separation step, the washing step, and the second separation step. [Aspect 2] When the flow rate of the crude product is A (L / h), the volume V of the first stirring tank M1 (L) and the volume V of the second stirring tank M2 (L) are each in the range of 0.05×A to 0.5×A (L), and the method for producing a 1,4-diiodooctafluorobutane product according to Aspect 1. [Aspect 3] When the flow rate of the crude product is A (L / h), the volume V of the first separation tank S1 (L) and the volume V of the second separation tank S2 (L) are each in the range of 0.2×A to 1.0×A (L), and the method for producing a 1,4-diiodooctafluorobutane product according to Aspect 1 or 2. [Aspect 4] When the flow rate of the crude product is A (L / h), the height H of the first separation tank S1 (m) and the height H of the second separation tank S2 (m) are each in the range of 0.05×A to 0.5×A (m), and the method for producing a 1,4-diiodooctafluorobutane product according to any one of Aspects 1 to 3. [Aspect 5] The method for producing a 1,4-diiodooctafluorobutane product according to any one of Embodiments 1 to 4, wherein each of the first separation tank and the second separation tank is one.

Advantages of the Invention

[0010] According to the present invention, a 1,4-diiodooctafluorobutane product with suppressed coloring can be produced with high efficiency.

Brief Description of the Drawings

[0011]

Figure 1

Modes for Carrying Out the Invention

[0012] [Method for Producing 1,4-Diiodooctafluorobutane Product] The present invention provides a method for producing a 1,4-diiodooctafluorobutane product. The method for producing a 1,4-diiodooctafluorobutane product according to an embodiment includes the following steps (1) to (4). Steps (1) to (4) are carried out continuously. (1) Decolorization step of mixing a crude product containing 1,4-diiodooctafluorobutane with an aqueous solution of a reducing agent in a first stirring tank to obtain a decolorized first mixture (2) First separation step of separating the first mixture into a heavy phase containing 1,4-diiodooctafluorobutane and a light phase containing water in a first separation tank (3) Washing step of mixing the heavy phase with water in a second stirring tank to obtain a second mixture containing a washed heavy phase (4) Second separation step of separating the second mixture into a heavy phase containing 1,4-diiodooctafluorobutane and a light phase containing water in a second separation tank to obtain a 1,4-diiodooctafluorobutane product

[0013] FIG. 1 shows a schematic diagram of an apparatus used in the method for producing a 1,4-diiodooctafluorobutane product according to an embodiment. Hereinafter, each step will be described with reference to FIG. 1.

[0014] (1) Decolorization step In the decolorization step, a crude product containing 1,4-diiodooctafluorobutane is mixed with an aqueous reducing agent solution in a first stirring tank to obtain a decolorized first mixture.

[0015] The crude product containing 1,4-diiodooctafluorobutane can be obtained by subjecting 1,2-diiodotetrafluoroethane to a telomerization reaction in the presence of iodine (I2). The crude product preferably undergoes a conversion step of adding tetrafluoroethylene to the telomerization reaction product and reacting it with I2 to convert it to 1,2-diiodotetrafluoroethane, and a rectification step of separating 1,4-diiodooctafluorobutane from other fluorocarbon compounds such as 1,2-diiodotetrafluoroethylene and 1,6-diiodododecafluorohexane.

[0016] The content of 1,4-diiodooctafluorobutane in the crude product is preferably 99% by mass or more, more preferably 99.5% by mass or more, and still more preferably 99.9% by mass or more.

[0017] The content of I2 in the crude product is not particularly limited, and may be, for example, 0.01 mass ppm to 1000 mass ppm, preferably 0.01 mass ppm to 100 mass ppm, and more preferably 0.01 mass ppm to 10 mass ppm.

[0018] The reducing agent contained in the aqueous reducing agent solution is not particularly limited as long as it can reduce and decolorize I2, but is preferably at least one selected from the group consisting of sodium thiosulfate, sodium bisulfite, and sodium dithionite, more preferably at least one selected from the group consisting of sodium thiosulfate and sodium bisulfite, and still more preferably sodium thiosulfate.

[0019] The content of the reducing agent in the aqueous reducing agent solution is not particularly limited, and may be, for example, 0.05% by mass to 50% by mass, preferably 0.1% by mass to 10% by mass, and more preferably 0.1% by mass to 5% by mass.

[0020] The crude product is supplied from the crude product storage tank 1 to the first stirring tank 3 via the pump 10, and the aqueous reducing agent solution is supplied from the aqueous reducing agent solution storage tank 2 to the first stirring tank 3 via the pump 10. The crude product and the aqueous reducing agent solution are mixed in the first stirring tank 3. As shown in FIG. 1, the crude product and the aqueous reducing agent solution may be supplied to the preliminary stirring tank 4, preliminarily mixed in the preliminary stirring tank 4, and then further mixed in the first stirring tank 3. The mixing can be performed using the stirring device 11. The stirring device 11 is not particularly limited. Examples of the shape of the stirring blades include paddle blades, large blades, and turbine blades. In order to improve the stirring efficiency, a baffle plate may be installed inside the first stirring tank 3. By mixing the crude product and the aqueous reducing agent solution, a first mixture in which I2 contained in the crude product is reduced and decolorized is obtained. By continuously supplying the crude product and the aqueous reducing agent solution, the preliminary mixture continuously moves from the discharge port of the preliminary stirring tank 4 to the first stirring tank 3, and the first mixture continuously moves from the discharge port of the first stirring tank 3 to the first separation tank 5.

[0021] The density of 1,4-diiodooctafluorobutane is 2.497 g / cm 3 and the density of the aqueous reducing agent solution depends on the reducing agent content but is generally 1.0 g / cm 3 Thus, since the density of the crude product is greater than that of the aqueous reducing agent solution, as shown in FIG. 1, it is preferable to introduce the aqueous reducing agent solution from the lower part inside the preliminary stirring tank 4 and the first stirring tank 3, and introduce the crude product from the upper part inside the preliminary stirring tank 4 and the first stirring tank 3. Thereby, the mixing of the crude product and the aqueous reducing agent solution can be promoted.

[0022] In the first separation tank 5, the first mixture is separated into a heavy phase P1 containing 1,4-diiodooctafluorobutane and a light phase W1 containing water. As described above, since the density difference between 1,4-diiodooctafluorobutane and water is large, the light phase W1 is retained in the upper layer in the first separation tank 5, and the heavy phase P1 is retained in the lower layer, and the heavy phase P1 and the light phase W1 can be quickly separated. The light phase W1 is discharged as reducing agent wastewater from the upper part of the first separation tank 5. The heavy phase P1 is transferred from the lower part of the first separation tank 5 to the second stirring tank 7. The extraction methods of the heavy phase P1 and the light phase W1 are not particularly limited. Preferably, the light phase W1 is caused to flow out from the overflow port as shown in FIG. 1. The heavy phase P1 may be forcibly extracted using a pump. Preferably, a pipe installed at the lower part of the first separation tank 5 is raised and its upper part is opened, and a horizontal pipe is installed at a position where only the heavy phase P1 on the side of the raised pipe can flow out and caused to flow out. In FIG. 1, the pipe with the upper part opened and the horizontal pipe are collectively shown as the heavy phase extraction pipe 12.

[0023] Water is supplied from the washing water storage tank 6 to the second stirring tank 7 via the pump 10. The water is not particularly limited, and tap water, ion-exchanged water, etc. can be used according to the use of the 1,4-diiodooctafluorobutane product. In the second stirring tank 7, the heavy phase and water are mixed. The mixing can be carried out using the stirring device 11. The stirring device 11 is not particularly limited. Examples of the shape of the stirring blades include paddle blades, large blades, and turbine blades. In order to improve the stirring efficiency, a baffle plate may be installed inside the second stirring tank 7. By mixing the heavy phase and water, salts in the heavy phase are washed away. The second mixture containing the washed heavy phase continuously moves from the discharge port of the second stirring tank 7 to the second separation tank 8. As shown in FIG. 1, it is preferable to introduce water from the lower part inside the second stirring tank 7 and introduce the heavy phase P1 from the upper part inside the second stirring tank 7. Thereby, the mixing of the heavy phase P1 and water can be promoted.

[0024] In the second separation tank 8, the second mixture is separated into a heavy phase P2 containing 1,4-diiodooctafluorobutane and a light phase W2 containing water. As described above, since the density difference between 1,4-diiodooctafluorobutane and water is large, the light phase W2 is retained in the upper layer in the second separation tank 8, and the heavy phase P2 is retained in the lower layer, and the heavy phase P2 and the light phase W2 can be quickly separated. The light phase W2 is discharged as washing waste water from the upper part of the second separation tank 8. The heavy phase P2 is transferred from the lower part of the second separation tank 8 to the product container 9 and stored in the product container 9 as a 1,4-diiodooctafluorobutane product. The method for extracting the heavy phase P2 and the light phase W2 is not particularly limited. The light phase W2 is preferably allowed to flow out from the overflow port as shown in FIG. 1. The heavy phase P2 may be forcibly extracted using a pump. Preferably, a pipe installed at the lower part of the second separation tank 8 is raised and its upper part is opened, and a horizontal pipe is installed at a position where only the heavy phase P2 on the side of the raised pipe can flow out and allowed to flow out. In FIG. 1, the pipe with the upper part opened and the horizontal pipe are collectively shown as the heavy phase extraction pipe 12.

[0025] Considering the mixing and separation behaviors due to the large density difference between 1,4-diiodooctafluorobutane and the reducing agent aqueous solution or water, the device used for the decolorization treatment can be designed.

[0026] In one embodiment, when the flow rate of the crude product is A (L / h), the volume V M1 (L) of the first stirring tank and the volume V M2 (L) of the second stirring tank are each in the range of 0.05×A to 0.5×A (L), preferably in the range of 0.05×A to 0.3×A (L), more preferably in the range of 0.05×A to 0.2×A (L). According to this embodiment, even when using a low-output stirring device by reducing the volumes of the first stirring tank and the second stirring tank, the crude product and the reducing agent aqueous solution, or the heavy phase and water, can be sufficiently mixed, and the degree of freedom of the device layout can be increased.

[0027] In one embodiment, when the flow rate of the crude product is A (L / h), the volume V S1(L) and the volume V of the second separation tank S2 (L) is in the range of 0.2×A to 1.0×A (L), preferably in the range of 0.2×A to 0.8×A (L), and more preferably in the range of 0.2×A to 0.6×A (L). According to this embodiment, the volumes of the first separation tank and the second separation tank can be reduced, and the degree of freedom of the device layout can be increased.

[0028] In one embodiment, when the flow rate of the crude product is A (L / h), the height H of the first separation tank S1 (m) and the height H of the second separation tank S2 (m) is in the range of 0.05×A to 0.5×A (m), preferably in the range of 0.05×A to 0.4×A (m), and more preferably in the range of 0.05×A to 0.3×A (m). According to this embodiment, while ensuring the separation efficiency of the light phase and the heavy phase in the first separation tank and the second separation tank, the degree of freedom of the device layout can be increased.

[0029] In one embodiment, the first separation tank and the second separation tank are each one. As described above, since the density difference between 1,4-diiodooctafluorobutane and the aqueous reducing agent solution or water is large, sufficient separation efficiency can be obtained without making the first separation tank and the second separation tank multi-stage as in this embodiment.

[0030] All documents mentioned in this specification are hereby incorporated by reference in their entirety into this specification.

[0031] The examples described below are for illustrative purposes only and do not limit the technical scope of the present invention. The technical scope of the present invention is limited only by the description in the claims. Changes to the present invention, for example, addition, deletion, and substitution of the constituent elements of the present invention, can be made on the condition that the gist of the present invention is not deviated from.

Examples

[0032] The present invention will be described in more detail below based on examples, but these do not limit the present invention in any way.

[0033] [Example 1] Using the apparatus shown in FIG. 1, the crude product containing 1,4-diiodooctafluorobutane was continuously decolorized at 25° C. under an atmospheric pressure atmosphere. The dimensions of each tank of the apparatus were as follows. Preliminary stirring tank 4: volume 80 mL First stirring tank 3: volume 500 mL First separation tank 5: inner diameter 85 mm φ, height 500 mm Second stirring tank 7: volume 500 mL Second separation tank 8: inner diameter 85 mm φ, height 500 mm

[0034] The crude product was pumped from the crude product storage tank 1 to the preliminary stirring tank 4 at a flow rate of 6 L / h. The content of 1,4-diiodooctafluorobutane in the crude product was 99.9% by mass. The treatment amount of the crude product per unit time calculated as the density of the crude product being 2.497 g / cm 3 was 15 kg / h. An aqueous solution of 0.5% by mass sodium thiosulfate was pumped from the reducing agent aqueous solution storage tank 2 to the preliminary stirring tank 4 at a flow rate of 5.4 L / h. Water was pumped from the washing water storage tank 6 to the second stirring tank 7 at a flow rate of 5.4 L / h.

[0035] Using the stirring devices 11 respectively attached to the preliminary stirring tank 4, the first stirring tank 3, and the second stirring tank 7, the contents of each tank were stirred and mixed at 600 rpm respectively.

[0036] The mixture decolorized in the preliminary stirring tank 4 and then in the first stirring tank 3 moved to the first separation tank 5, where it was separated into a light phase W1 containing reducing agent wastewater and a heavy phase P1 containing 1,4-diiodooctafluorobutane in the first separation tank 5. The light phase W1 was discharged from the upper part of the first separation tank 5 at a flow rate of 5.4 L / h, and the heavy phase P1 moved to the second stirring tank 7 from the lower part.

[0037] The heavy phase is washed in the second stirring tank 7, and the mixture containing the heavy phase and water moves to the second separation tank 8, where it is separated into a light phase W2 containing washing waste water and a heavy phase P2 containing 1,4-diiodooctafluorobutane in the second separation tank 8. The light phase W2 is discharged from the upper part of the second separation tank 8 at a flow rate of 5.4 L / h, and the heavy phase P2 moves from the lower part to the product container 9, where the 1,4-diiodooctafluorobutane product is stored. The 1,4-diiodooctafluorobutane product is colorless, and a series of processes were carried out continuously.

[0038] As described above, the embodiments of the present invention have been explained, but the present invention is not limited to these, and the devices, materials, various conditions, etc. used can be appropriately changed without departing from the spirit of the invention.

Explanation of symbols

[0039] 1 Crude product storage tank 2 Reducing agent aqueous solution storage tank 3 First stirring tank 4 Preliminary stirring tank 5 First separation tank 6 Washing water storage tank 7 Second stirring tank 8 Second separation tank 9 Product container 10 Pump 11 Stirring device 12 Heavy phase extraction pipe W1, W2 Light phase P1, P2 Heavy phase

Claims

1. A decolorization step of mixing a crude product containing 1,4-diiodooctafluorobutane with an aqueous reducing agent solution in a first stirring tank to obtain a decolorized first mixture; A first separation step of separating the first mixture into a heavy phase containing 1,4-diiodooctafluorobutane and a light phase containing water in a first separation tank; A washing step of mixing the heavy phase with water in a second stirring tank to obtain a second mixture containing a washed heavy phase; A second separation step of separating the second mixture into a heavy phase containing 1,4-diiodooctafluorobutane and a light phase containing water in a second separation tank to obtain a 1,4-diiodooctafluorobutane product; A method for producing a 1,4-diiodooctafluorobutane product, comprising continuously performing the decolorization step, the first separation step, the washing step, and the second separation step.

2. When the flow rate of the crude product is A (L / h), the volume V of the first stirring tank Ｍ１ (L) and the volume V of the second stirring tank Ｍ２ (L) are respectively in the range of 0.05 × A to 0.5 × A (L), and the method for producing a 1,4-diiodooctafluorobutane product according to claim 1.

3. When the flow rate of the crude product is A (L / h), the volume V Ｓ１ (L) of the first separation tank and the volume V Ｓ２ (L) of the second separation tank are each in the range of 0.2 × A to 1.0 × A (L). The method for producing a 1,4-diiodooctafluorobutane product according to claim 1 or 2.

4. When the flow rate of the crude product is A (L / h), the height H of the first separation tank Ｓ１ (m) and the height H of the second separation tank Ｓ２ (m) are each in the range of 0.05 × A to 0.5 × A (m), and the method for producing a 1,4-diiodooctofluorobutane product according to claim 1 or 2.

5. The method for producing a 1,4-diiodooctafluorobutane product according to claim 1 or 2, wherein each of the first separation tank and the second separation tank is one.

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