Method for producing 1,4-diiodoperfluorobutane, method for producing octafluorocyclobutane, and method for reusing iodine in reaction product

Abstract

A method for producing 1,4-diiodoperfluorobutane involves obtaining a mixture A by mixing iodine and 1,2-diiodoperfluoroethane, and obtaining a reaction product B containing 1,4-diiodoperfluorobutane by reacting the mixture A, and the content of iodine in the mixture A is 5 mol% or more relative to the total molar amount of iodine and 1,2-diiodoperfluoroethane.

Description

Method for producing 1,4-diiodoperfluorobutane, method for producing octafluorocyclobutane, and method for recycling iodine in a reactant

[0001] The present disclosure relates to a method for producing 1,4-diiodoperfluorobutane, a method for producing octafluorocyclobutane, and a method for recycling iodine in the reaction mixture.

[0002] Formula I-(CF ２ CF ２ ) ｎ The α,ω-diiodoperfluoroalkanes represented by the formula -I (n is an integer of 2 to 6) are useful as intermediates in the synthesis of various fluorochemicals and fluoropolymers.

[0003] Patent Document 1 discloses a method for producing α,ω-diiodoperfluoroalkanes using 1,2-diiodoperfluoroethane and tetrafluoroethylene.

[0004] Japanese Patent Application Laid-Open No. 2004-168753

[0005] However, the production method described in Patent Document 1 includes periodic cooling and discharge steps, resulting in poor productivity. The present disclosure has been made in light of the above, and relates to providing a method for producing 1,4-diiodoperfluorobutane, which can produce 1,4-diiodoperfluorobutane from 1,2-diiodoperfluoroethane with high selectivity, a method for producing octafluorocyclobutane, and a method for recycling iodine in the reactants.

[0006] The present disclosure includes the following aspects. <1> A method for producing 1,4-diiodoperfluorobutane, comprising: mixing iodine and 1,2-diiodoperfluoroethane to obtain a mixture A; and reacting the mixture A to obtain a reaction product B containing 1,4-diiodoperfluorobutane, wherein the iodine content in the mixture A is 5 mol % or more relative to the total molar amount of iodine and the 1,2-diiodoperfluoroethane. <2> A method for producing 1,4-diiodoperfluorobutane according to <1>, wherein the iodine content in the mixture A is 40 mol % or less relative to the total molar amount of iodine and the 1,2-diiodoperfluoroethane. <3> A method for producing 1,4-diiodoperfluorobutane according to <1> or <2>, comprising reacting the mixture A at 200 to 300°C to obtain the reaction product B. <4> The method for producing 1,4-diiodoperfluorobutane according to <3>, further comprising cooling the obtained reaction product B to less than 60°C. <5> The method for producing 1,4-diiodoperfluorobutane according to <4>, further comprising recovering a liquid phase containing 1,4-diiodoperfluorobutane from the cooled reaction product B. <6> The method for producing octafluorocyclobutane, comprising recovering a gas phase containing octafluorocyclobutane from the cooled reaction product B according to <4>. <7> The method for producing octafluorocyclobutane according to <6>, wherein the recovering comprises at least one of contacting the gas phase containing octafluorocyclobutane in the cooled reaction product B with an absorption liquid, contacting with an adsorbent, distilling, and rectifying. <8> A method for recycling iodine in a reactant, the method comprising: obtaining the reactant B containing iodine by using the method for producing 1,4-diiodoperfluorobutane according to any one of <1> to <5>; mixing the iodine in the reactant B with tetrafluoroethylene; and reacting the iodine in the reactant B with the tetrafluoroethylene to obtain a reactant C containing 1,2-diiodoperfluoroethane.<9> The method for recycling iodine in a reactant according to <8>, comprising obtaining a fractionated distillate containing 1,2-diiodoperfluoroethane by fractionating the reactant C. <10> The method for recycling iodine in a reactant according to <9>, comprising mixing iodine and 1,2-diiodoperfluoroethane to obtain a mixture D, and reacting the mixture D to obtain a reactant E containing 1,4-diiodoperfluorobutane, wherein the iodine content in the mixture D is 5 mol % or more relative to the total molar amount of iodine and 1,2-diiodoperfluoroethane, and the 1,2-diiodoperfluoroethane comprises the fractionated distillate containing 1,2-diiodoperfluoroethane. <11> The method for recycling iodine in the reactant according to <10>, comprising: reacting the mixture D at 200 to 300°C to obtain the reactant E; cooling the obtained reactant E to less than 60°C; and recovering at least one of a liquid phase containing 1,4-diiodoperfluorobutane and a gas phase containing octafluorocyclobutane from the cooled reactant E.

[0007] According to the present disclosure, there are provided a method for producing 1,4-diiodoperfluorobutane, which can produce 1,4-diiodoperfluorobutane from 1,2-diiodoperfluoroethane with high selectivity, a method for producing octafluorocyclobutane, and a method for recycling iodine in the reaction product.

[0008] An embodiment of the present disclosure will be described in detail below. However, the present disclosure is not limited to the following embodiment. In the following disclosure, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the present disclosure.

[0009] In the present disclosure, when a numerical range is indicated using "to", the numerical values ​​before and after "to" are included as the lower and upper limits, respectively. In the present disclosure, when a numerical range is indicated in a stepped manner, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another stepped numerical range. Furthermore, in the present disclosure, when a numerical range is indicated, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. In the present disclosure, when multiple substances corresponding to each component are present in the composition, the content of each component refers to the total content of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, when multiple elements are listed using "or", it does not exclude the selection of multiple elements in combination unless a technical contradiction occurs, unless otherwise specified. In the present disclosure, when an element is expressed in the singular, it does not exclude the presence of multiple elements unless a technical contradiction occurs, unless otherwise specified. In the present disclosure, multiple exemplary embodiments described separately may be combined with each other to form a new embodiment unless mutually contradictory.

[0010] The abbreviations for each substance used in this disclosure are as follows: C2: 1,2-diiodoperfluoroethane C4: 1,4-diiodoperfluorobutane C6: 1,6-diiodoperfluorohexane C-318 (PFC-318): octafluorocyclobutane TFE: tetrafluoroethylene I ２ : Iodine

[0011] <<Method for producing C4>> The method for producing C4 of the present disclosure includes: ２ and C2 to obtain a mixture A, and reacting the mixture A to obtain a reactant B containing C4, ２ The content of I ２ and C2.

[0012] In the method for producing C4 of the present disclosure, at least the following main reaction, side reaction 1, and side reaction 2 occur.

[0013]

[0014] According to the method for producing C4 of the present disclosure, the progress of side reactions 1 and 2 is dramatically suppressed compared to conventional methods, and as a result, C4 can be produced with high selectivity using C2 as a raw material.

[0015] <Mixture A> The method for producing C4 of the present disclosure is ２ and C2 to obtain mixture A.

[0016] From the viewpoint of the likelihood of the main reaction occurring, I in mixture A ２ The content of I ２ The amount of I in mixture A is 5 mol % or more relative to the total molar amount of I and C2. ２ The content of I ２ and C2, and from the viewpoint of increasing the C4 / C6 (the molar ratio of C4 to C6 in the gas phase obtained by cooling the reactant B), the amount is preferably 10 mol % or more, more preferably 15 mol % or more, and from the viewpoint of increasing the C4 / C6 (the molar ratio of C4 to C6 in the gas phase obtained by cooling the reactant B), further preferably 20 mol % or more, particularly preferably 25 mol % or more.

[0017] I in Mixture A ２ The content of I ２ The content of I in mixture A is preferably 40 mol % or less, more preferably less than 40 mol %, still more preferably 38 mol % or less, and particularly preferably 35 mol % or less, based on the total molar amount of I and C2. ２ When the content of is further reduced, the side reactions 1 and 2 occur more easily than the main reaction, and C-318, C6, etc. can be produced with high selectivity.

[0018] I in Mixture A ２ The total amount of C2 is preferably from 50 to 100 mol %, more preferably from 70 to 100 mol %, and even more preferably from 90 to 100 mol %.

[0019] Mixture A contains I ２ Substances other than C1 and C2 may be included. ２and substances other than C2 include iodine-containing perfluoroalkyl compounds other than C2, fluorocarbons, nitrogen, oxygen, argon, carbon dioxide, and water. Fluorocarbons include C-318 and TFE. Iodine-containing perfluoroalkyl compounds other than C2 include C4, C6, 1,8-diiodoperfluorooctane, 1-iodoperfluoroethane, 1-iodoperfluoropropane, 1-iodoperfluorobutane, 2-iodoperfluoropropane, 1-iodoperfluoropentane, 1-iodoperfluorohexane, 1-iodoperfluoroheptane, and 1-iodoperfluorooctane.

[0020] I ２ The conditions for mixing I and C2 are not particularly limited. ２ The components C1 and C2 may be mixed in the same container, and may be further stirred. The mixing may be carried out under reduced pressure or pressure. ２ After adding C1, the pressure inside the vessel may be reduced, and C2 may be further added to the reduced pressure vessel. The pressure in the reduced pressure state is preferably -1 to -0.0001 MPaG, more preferably -0.5 to -0.001 MPaG, and even more preferably -0.2 to -0.01 MPaG. The mixing temperature is preferably 4 to 50°C, more preferably 10 to 40°C, and even more preferably 20 to 30°C.

[0021] <Reactant B> The method for producing C4 of the present disclosure includes reacting the mixture A to obtain reactant B containing C4.

[0022] From mixture A, reactant B is obtained (i.e., I ２ The detailed reaction conditions are not particularly limited. From the viewpoint of facilitating the main reaction, the reaction temperature is preferably 200 to 300°C, more preferably 210 to 250°C, and even more preferably 220 to 240°C. The reaction time is preferably 0.1 to 100 hours, more preferably 1 to 50 hours, and even more preferably 5 to 20 hours. The reaction pressure may be a natural pressure, and is preferably 0.1 to 10 MPa, more preferably 0.5 to 5 MPa, and even more preferably 1 to 3 MPa. The reaction may be carried out with stirring.

[0023] Furthermore, from the viewpoint of separating the reaction product B obtained by the reaction into a gas phase and a liquid phase, it is preferable to cool it to less than 60° C. The cooling temperature is more preferably 50° C. or less, even more preferably 45° C. or less, and particularly preferably 40° C. or less. The cooling temperature is preferably 0° C. or more, more preferably 10° C. or more, and even more preferably 20° C. or more.

[0024] (Liquid Phase) The C4 production method of the present disclosure may include recovering a C4-containing liquid phase from the cooled reaction product B. The method for recovering the C4-containing liquid phase is not particularly limited, and the remaining liquid phase may be recovered by discharging the gas phase.

[0025] The liquid phase contains C4, and also C2, C6, and I ２ In the liquid phase, C2 is preferably 5 to 40 mol %, C4 is preferably 5 to 30 mol %, C6 is preferably 0.1 to 10 mol %, and I ２ is preferably 10 to 50 mol %.

[0026] By purifying the liquid phase, C2, C4, C6, or I having a high purity (preferably a purity of 99 mol % or more, more preferably 99.9 mol % or more, and even more preferably 99.99 mol % or more) can be obtained. ２ The purification method is not particularly limited, and examples thereof include distillation and rectification.

[0027] (Gas Phase) The method for producing C4 of the present disclosure may include recovering a gas phase from the cooled reactant B. The gas phase may include C2, C4, C6, C-318, and I. ２ In the gas phase, C2 is preferably 1 to 20 mol %, C4 is preferably 0.1 to 5 mol %, C6 is preferably 0.01 to 1 mol %, C-318 is preferably 30 to 95 mol %, and I ２ is preferably 1 to 30 mol %.

[0028] By purifying the gas phase, high purity (preferably 99 mol % or more, more preferably 99.9 mol % or more, and even more preferably 99.99 mol % or more) C2, C4, C6, C-318, or I ２The purification method is not particularly limited, and examples thereof include a method including at least one of contacting with an absorption liquid, contacting with an adsorbent, distillation, and rectification. The explanations for the methods of contacting with an absorption liquid, contacting with an adsorbent, distillation, and rectification are the same as those in the "Method for producing C-318" described below.

[0029] In this disclosure, the reactant may be C2, C4, C6, C-318, or I ２ The presence of C-318 can be confirmed by the same method as the method for measuring the content of C-318 in the gas phase in the <<Production method of C-318>> described later.

[0030] <<Method for Producing C-318>> The method for producing C-318 of the present disclosure includes recovering a gas phase containing C-318 from the cooled reaction product B obtained by the method for producing C4 of the present disclosure. In other words, it is preferable that C-318 is also produced by the method for producing C4 of the present disclosure.

[0031] In the gas phase containing C-318, the C-318 content is preferably 50 to 100 mol %, more preferably 70 to 100 mol %, and even more preferably 90 to 100 mol %. In the present disclosure, the content of C-318 in the gas phase can be measured using a gas chromatograph under the following measurement conditions. Instrument body: 7890GC (manufactured by Agilent Technologies Inc.) Detector: Flame ionization detector (FID) Column: DB-1301 (manufactured by Agilent Technologies Inc.)

[0032] The gas phase containing C-318 may contain substances other than C-318, such as iodine-containing perfluoroalkyl compounds, fluorocarbons, nitrogen, oxygen, argon, carbon dioxide, and water. Fluorocarbons include TFE. Iodine-containing perfluoroalkyl compounds include C2, C4, C6, 1,8-diiodoperfluorooctane, 1-iodoperfluoroethane, 1-iodoperfluoropropane, 1-iodoperfluorobutane, 2-iodoperfluoropropane, 1-iodoperfluoropentane, 1-iodoperfluorohexane, 1-iodoperfluoroheptane, and 1-iodoperfluorooctane.

[0033] In the method for producing C-318, the recovery preferably includes at least one of contacting the gas phase containing C-318 in the cooled reactant B with an absorption liquid, contacting with an adsorbent, distilling, and rectifying.

[0034] By contacting the gas phase containing C-318 with an absorbing solution, the impurities in the gas phase are absorbed by the absorbing solution. Alternatively, by contacting the gas phase containing C-318 with an adsorbent, the impurities in the gas phase are adsorbed by the adsorbent.

[0035] The method for contacting the absorbent with the absorbent is not particularly limited. ２ , C2, C4, etc. ２ Chemical absorption liquid (water, alkaline aqueous solution, etc.) that absorbs C2, C4, etc., or I ２ By utilizing the physical dissolution of ２ Examples of suitable adsorbents include physical absorption liquids (such as iodine-containing perfluoroalkyl compounds) that absorb the iodine-containing compounds. The details of the method for contacting the adsorbent are not particularly limited. Examples of adsorbents include carbon materials (such as activated carbon) and metal oxides (such as silica and alumina). The details of the distillation method are not particularly limited, and may be an atmospheric pressure method, a reduced pressure method, or a pressurized method, and examples include simple distillation, continuous distillation, and steam distillation. The details of the rectification method are not particularly limited, and may be an atmospheric pressure method, a reduced pressure method, or a pressurized method, and may be batch distillation or continuous distillation. In particular, reduced pressure distillation at 85 to 95 kPa and heating at 50 to 150°C are preferred.

[0036] In the gas phase containing C-318 that has been subjected to at least one of contact with an absorption liquid, contact with an adsorbent, distillation, and rectification, the C-318 content is preferably 90 to 100 mol%, more preferably 99 to 100 mol%, even more preferably 99.9 to 100 mol%, and particularly preferably 99.99 to 100 mol%.

[0037] <I in the reactant ２ Method for Reusing I in the Reaction Product of the Present Disclosure ２ The recycling method of I is to use the C4 manufacturing method of the present disclosure. ２ obtaining the reactant B containing I;２ and TFE; and ２ and reacting the above-mentioned C2 with the TFE to obtain a reactant C containing C2.

[0038] I in the reactants of the present disclosure ２ In the recycling method, at least the following reactions occur:

[0039]

[0040] That is, I in the reactants of the present disclosure ２ In the recycling method of the present disclosure, unreacted I in the reactant B obtained by the C4 production method of the present disclosure ２ and TFE to obtain C2. Then, C4 can be produced using the obtained C2 according to the above-described method for producing C4 of the present disclosure.

[0041] Furthermore, unreacted I in reactant B ２ The addition of I to TFE ２ is consumed, making it easier to handle. ２ includes solids.

[0042] <Mixing> From the viewpoint of facilitating the reaction, I in the reactant B ２ TFE can be mixed in an amount of preferably 80 mol % or more, more preferably 90 mol % or more, and even more preferably 100 mol % or more.

[0043] From the viewpoint of suppressing side reactions, I in the reactant B ２ TFE can be mixed with the above in an amount of preferably 110 mol % or less.

[0044] The mixture obtained by mixing contains I ２ and may contain substances other than TFE. ２and substances other than TFE include iodine-containing perfluoroalkyl compounds, fluorocarbons other than TFE, nitrogen, oxygen, argon, carbon dioxide, and water. Examples of iodine-containing perfluoroalkyl compounds include C2, C4, C6, 1,8-diiodoperfluorooctane, 1-iodoperfluoroethane, 1-iodoperfluoropropane, 1-iodoperfluorobutane, 2-iodoperfluoropropane, 1-iodoperfluoropentane, 1-iodoperfluorohexane, 1-iodoperfluoroheptane, and 1-iodoperfluorooctane. Examples of fluorocarbons include C-318.

[0045] I in the reactants of the present disclosure ２ In the recycling method of the above, I in the reactant B ２ The detailed method for mixing the reactant B and the TFE is not particularly limited. ２ The reactant B and TFE may be mixed in the same vessel, and may be further stirred. The mixing may be carried out under reduced pressure or pressure. ２ After adding the reactant B, the pressure inside the vessel may be reduced, and TFE may be further added to the reduced pressure vessel. The pressure in the reduced pressure state is preferably -1 to -0.0001 MPaG, more preferably -0.5 to -0.001 MPaG, and even more preferably -0.2 to -0.01 MPaG. The mixing temperature is preferably 4 to 50°C, more preferably 10 to 40°C, and even more preferably 20 to 30°C. From the viewpoint of excellent reactivity, TFE is used as the reactant B in the reaction mixture. ２ The amount of continuous addition is preferably 0.01 to 10 mol / hour, more preferably 0.1 to 5 mol / hour, and even more preferably 0.3 to 2 mol / hour. That is, mixing and the reaction described below may be carried out simultaneously. Note that TFE is added to I in the reactant B. ２ It may be added intermittently.

[0046] <Reactant C> I in the reactants of the present disclosure ２ In the recycling method of the above, I in the reactant B ２ The detailed method for obtaining a reactant C containing C2 by reacting with the TFE is not particularly limited.

[0047] I in the reactant B ２ The reaction temperature for obtaining reaction product C from the above-mentioned TFE is preferably 50 to 300°C, more preferably 100 to 200°C, and even more preferably 120 to 150°C, from the viewpoint of facilitating the reaction. The reaction time is preferably 0.1 to 100 hours, more preferably 1 to 50 hours, and even more preferably 5 to 20 hours. The reaction pressure may be a natural pressure, and is preferably 0.01 to 10 MPa, more preferably 0.1 to 5 MPa, and even more preferably 0.2 to 1 MPa. The reaction may be carried out with stirring.

[0048] The obtained reaction product C may be cooled to less than 60° C. from the viewpoint of separating it into a gas phase and a liquid phase. The cooling temperature is preferably 40° C. or less, more preferably 45° C. or less, and particularly preferably 40° C. or less. The cooling temperature is preferably 0° C. or more, more preferably 10° C. or more, and even more preferably 20° C. or more.

[0049] Reactant C contains C2, and also C4, C6, C-318, and I ２ In the reactant, C2 preferably accounts for 30 to 85 mol %, more preferably 45 to 85 mol %, and even more preferably 60 to 85 mol %.

[0050] I in the reactants of the present disclosure ２ The recycling method of (1) may include purifying the reactant C to obtain a purified product containing C2. By the purification, C2 of high purity (preferably 99 mol% or more, more preferably 99.9 mol% or more, and even more preferably 99.99 mol% or more) may be obtained. The purification method is not particularly limited, and examples thereof include at least one method selected from the group consisting of distillation, rectification, and contact with an adsorbent.

[0051] I in the reactants of the present disclosure ２ In the recycling method of (1), it is preferable to obtain a fractionated product containing C2 by fractionating the reactant C.

[0052] The details of the distillation method are not particularly limited, and may be atmospheric pressure, reduced pressure, or pressurized, and examples thereof include simple distillation, continuous distillation, and steam distillation. The details of the rectification method are not particularly limited, and may be atmospheric pressure, reduced pressure, or pressurized, and may be batch distillation or continuous distillation. Specifically, reduced pressure distillation at 5 to 20 kPa and heating at 50 to 150°C are preferred. The details of the method of contacting with the adsorbent are not particularly limited. Examples of adsorbents include carbon materials (activated carbon, etc.) and metal oxides (silica, alumina, etc.).

[0053] <Mixture D> I in the reaction mixture of the present disclosure ２ The method of reuse is I ２ and C2 to obtain a mixture D, and reacting the mixture D to obtain a reactant E containing C4, ２ The content of I ２ and C2, and C2 is 5 mol % or more relative to the total molar amount of I in the reactant of the present disclosure. ２ Preferably, the fractionated product contains C2 and is obtained by the recycling method of the above.

[0054] I ２ The description of the process for mixing C1 with C2 to obtain mixture D is given in the section entitled "Method for producing C4" of the present disclosure, including definitions, examples, and preferred embodiments. ２ The same applies to the description regarding the mixing of C2 and I in the reactants of the present disclosure to obtain mixture A. ２ In the rectified product, the purity of C2 is preferably 99 mol % or more, more preferably 99.9 mol % or more, and even more preferably 99.99 mol % or more.

[0055] The explanation regarding obtaining a reactant E containing C4 by reacting mixture D is the same as the explanation regarding obtaining a reactant B containing C4 by reacting mixture A described in the "Method for producing C4" of the present disclosure, including definitions, examples, preferred embodiments, etc.

[0056] That is, I in the reactants of the present disclosure ２The recycling method of the above preferably includes: reacting the mixture D at 200 to 300°C to obtain the reaction product E; further cooling the obtained reaction product E to less than 60°C; and recovering at least one of a liquid phase containing C4 and a gas phase containing C-318 from the cooled reaction product E.

[0057] <Applications> C2, C4, and C6 produced by the method of the present disclosure are used as surfactants, solvents, heat transfer media, agricultural chemicals, electronic materials, and pharmaceutical intermediates. C-318 is used as an etching gas in the etching process and a cleaning gas in the cleaning process in the semiconductor device manufacturing process.

[0058] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples as long as it does not deviate from the gist of the disclosure. Example 1 is a comparative example, and Examples 2 to 9 are working examples.

[0059] <<Production of C4 and C-318>> <Example 1> A 1.5 L Hastelloy reactor was depressurized to -0.09 MPaG, and 5.65 moles of C2 were charged. The reactor was heated to 230°C, reacted for 10 hours, and then cooled to 40°C. The gas phase obtained was trapped and recovered in an ice bath cooled to -40°C, and its mass was measured and analyzed using a gas chromatograph under the following measurement conditions. The mass of the resulting liquid phase was also measured and its mass was measured using a gas chromatograph under the following measurement conditions. C4 / C6 (the molar ratio of C4 to C6) and C4 / C-318 (the molar ratio of C4 to C-318) were calculated as the composition ratio of the entire combined gas and liquid phases obtained. The results are shown in Table 1. Instrument body: 7890GC (Agilent Technologies) Detector: Flame ionization detector (FID) Column: DB-1301 (Agilent Technologies)

[0060] <Example 2> A 1.5 L Hastelloy reactor was charged with I ２After charging 0.44 mol of C4, the pressure was reduced to -0.09 MPaG, and 5.65 mol of C2 were charged to obtain a mixture (Mixture A of the present disclosure). The reactor was heated to 230°C, and the reaction was carried out for 10 hours to obtain a reaction product (Reactant B of the present disclosure). The reactor was further cooled to 40°C. The gas phase obtained was trapped and recovered in an ice bath cooled to -40°C, and analyzed by mass measurement and gas chromatography in the same manner as in Example 1. The obtained liquid phase was also analyzed by mass measurement and gas chromatography, and the C4 / C6 and C4 / C-318 ratios were calculated as the composition ratios of the combined gas and liquid phases. The results are shown in Table 1.

[0061] <Examples 3 to 8> Reaction temperature, I in the mixture ２ I relative to the total molar amount of C2 ２ the content (mol%) of C2 in the mixture, the molar amount of I in the mixture, ２ Examples 3 to 8 were carried out in the same manner as Example 2, except that the molar amounts of were changed as shown in Table 1 below. The results are shown in Table 1.

[0062]

[0063] <I in the reactant ２ Example 9: Preparation of C2 using the recycling method of I in a 1.5 L Hastelloy reactor. ２ After charging 1.33 moles of C2, the pressure was reduced to -0.09 MPaG, and 5.65 moles of C2 were charged to obtain a mixture (Mixture A of the present disclosure). The reactor was heated to 230°C, and the reaction was carried out for 10 hours to obtain a reaction product (Reactant B of the present disclosure). The reactor was further cooled to 40°C. The gas phase was discharged until the pressure reached 0.35 MPaG, and the discharged gas phase was trapped in an ice bath cooled to -40°C, recovered, and its mass was measured, yielding 78.5 g. It was also analyzed by gas chromatography. The composition ratio (mol %) of the recovered gas phase was as follows: C2 / C4 / C6 / C-318 / I ２ = 15.2 / 3.7 / 0.3 / 74.1 / 6.7 The composition ratio (mol %) of the residue in the reactor after the gas phase was recovered was as follows: C2 / C4 / C6 / C-318 / I ２ = 36.1 / 16.1 / 1.7 / 0.0 / 46.0

[0064] That is, C-318 in the reaction product was recovered by discharging the gas phase of the reaction product.Furthermore, the gas phase of the reaction product was rectified to obtain 0.22 moles of C-318 with a purity of 99.99 mol%.

[0065] On the other hand, the residue in the reactor contained solid I ２ was present as an unreacted product. TFE was continuously added to the reactor containing the residue at an amount of 0.20 mol / hr, and the reaction was carried out at 130°C for 16 hours to obtain a reaction product (reactant C of the present disclosure). Analysis of the gas and liquid phases of this reaction product revealed the following composition ratio (mol %) in the total gas and liquid phases combined: C2 / C4 / C6 / C-318 / I ２ = 80.2 / 15.8 / 1.7 / 0.0 / 0.5

[0066] TFE was continuously added and the reaction was carried out at 130°C for 16 hours, after which rectification was carried out in the reactor to obtain 4.80 mol of C2 with a purity of 99.9 mol% and 0.94 mol of C4 with a purity of 99.9 mol%. ２ The amount of I that remained as an unreacted product was reduced from 46.0 mol % to 0.5 mol % after the reaction with TFE. ２ was found to have been utilized for the production of C2.

[0067] C2 obtained by rectification in the reactor after continuous addition of TFE and reaction at 130°C for 16 hours could be recycled as a raw material in the next batch in the above-mentioned <<Production of C4 and C-318>>.

[0068] As described above, Examples 2 to 9 show a method for producing C4 from C2 with high selectivity, a method for producing C-318, and the reduction of I in the reaction product. ２ A method for reusing was provided.

[0069] The disclosure of Japanese Patent Application No. 2024-013760, filed on January 31, 2024, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

[0070] The C4 production method of the present disclosure can produce C4 from C2 with high selectivity, and can also produce C-318 and C6. ２ By this recycling method, unreacted I in the C4 production method of the present disclosure ２ can be reused as raw materials for the production of C4. C2, C4, and C6 produced by the method of the present disclosure can be used as intermediates for surfactants, solvents, heat transfer media, agricultural chemicals, electronic materials, and pharmaceuticals. C-318 produced by the method of the present disclosure can be used as an etching gas in the etching step and a cleaning gas in the cleaning step in the semiconductor device manufacturing process.

Claims

1. A method for producing 1,4-diiodoperfluorobutane, comprising: mixing iodine and 1,2-diiodoperfluoroethane to obtain mixture A; and reacting mixture A to obtain reaction product B containing 1,4-diiodoperfluorobutane, wherein the iodine content in mixture A is 5 mol% or more relative to the total molar amount of iodine and 1,2-diiodoperfluoroethane.

2. The method for producing 1,4-diiodoperfluorobutane according to claim 1, wherein the iodine content in said mixture A is 40 mol % or less based on the total molar amount of iodine and 1,2-diiodoperfluoroethane.

3. The method for producing 1,4-diiodoperfluorobutane according to claim 1 or 2, which comprises reacting the mixture A at 200 to 300°C to obtain the reactant B.

4. The method for producing 1,4-diiodoperfluorobutane according to claim 3, further comprising cooling the obtained reaction product B to less than 60°C.

5. A method for producing 1,4-diiodoperfluorobutane according to claim 4, comprising recovering a liquid phase containing 1,4-diiodoperfluorobutane from the cooled reaction mixture B.

6. A method for producing octafluorocyclobutane, comprising recovering a gas phase containing octafluorocyclobutane from the cooled reactant B of claim 4.

7. The method for producing octafluorocyclobutane according to claim 6, wherein the recovering step comprises at least one of contacting the octafluorocyclobutane-containing gas phase in the cooled reactant B with an absorption liquid, contacting with an adsorbent, distilling, and rectifying.

8. A method for recycling iodine in a reactant, comprising: obtaining reactant B containing iodine using the method for producing 1,4-diiodoperfluorobutane according to claim 1 or 2; mixing the iodine in reactant B with tetrafluoroethylene; and reacting the iodine in reactant B with the tetrafluoroethylene to obtain reactant C containing 1,2-diiodoperfluoroethane.

9. The method for recycling iodine in a reactant according to claim 8, comprising rectifying reactant C to obtain a rectified product containing 1,2-diiodoperfluoroethane.

10. The method for recycling iodine in a reactant according to claim 9, comprising: mixing iodine and 1,2-diiodoperfluoroethane to obtain a mixture D; and reacting said mixture D to obtain a reactant E containing 1,4-diiodoperfluorobutane, wherein the iodine content in said mixture D is 5 mol % or more based on the total molar amount of iodine and 1,2-diiodoperfluoroethane, and said 1,2-diiodoperfluoroethane comprises said fractionated product containing 1,2-diiodoperfluoroethane.

11. The method for recycling iodine in a reactant according to claim 10, comprising: reacting the mixture D at 200 to 300°C to obtain the reactant E; cooling the obtained reactant E to a temperature of less than 60°C; and recovering at least one of a liquid phase containing 1,4-diiodoperfluorobutane and a gas phase containing octafluorocyclobutane from the cooled reactant E.

Images