Method for producing 1, 2, 3, 4-tetrachloro-1, 1, 2, 3, 4, 4-hexafluorobutane

Abstract

The purpose of the present invention is to make it possible to convert a by-product into a target product by a relatively simple operation in a series of processes for producing 1, 2, 3, 4-tetrachlorohexafluorobutane from 1, 3-butadiene, and to improve production efficiency throughout the process. A method for producing 1, 2, 3, 4-tetrachloro-1, 1, 2, 3, 4, 4-hexafluorobutane, which comprises a step (a) for producing 1, 2, 3, 4-tetrachloro-1, 1, 2, 3, 4, 4-hexafluorobutane by reacting chlorofluorobutane represented by formula (1): C4ClnF10-n (1) (in the formula, n is an integer satisfying 5 < = n < = 7) with chlorine monofluoride (ClF).

Description

Technical Field

[0001] The present invention relates to a method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane (hereinafter referred to as 1,2,3,4-tetrachlorohexafluorobutane) by chlorinating 1,3-butadiene to generate 1,2,3,4-tetrachlorobutane and replacing the hydrogen atoms of the 1,2,3,4-tetrachlorobutane with fluorine atoms. More specifically, the method comprises the following steps:

[0002] C4Cl n F 10-n (1)

[0003] A method for producing 1,2,3,4-tetrachlorohexafluorobutane, comprising the steps of reacting 1,2,3,4-tetrachlorohexafluorobutane (wherein n is 5≤n≤7) with chlorine monofluoride (ClF) to generate 1,2,3,4-tetrachlorohexafluorobutane and recovering the 1,2,3,4-tetrachlorohexafluorobutane. More specifically, the invention relates to a method for producing 1,2,3,4-tetrachlorohexafluorobutane, which is used as a synthetic raw material for hexafluoro-1,3-butadiene, which has attracted attention as a semiconductor etching gas, etc. Background Art

[0004] 1,2,3,4-Tetrachlorohexafluorobutane is an important compound as a raw material for synthesizing hexafluoro-1,3-butadiene, which is used as an etching gas for use in semiconductor microfabrication. Conventionally, the following methods described in the patent literature are known as methods for producing 1,2,3,4-tetrachlorohexafluorobutane.

[0005] (1) Japanese Patent Application Laid-Open No. 2006-342059 (Patent Document 1) describes a method of using a CC1X 1 X 2 -CC1X 3 -CC1X 4 -CC1X 5 X 6 A method for producing 1,2,3,4-tetrachlorohexafluorobutane by reacting a compound represented by (X is a hydrogen atom or a fluorine atom) with fluorine in a liquid phase.

[0006] (2) Japanese Patent No. 5274449 (Patent Document 2) describes a method for producing 1,2,3,4-tetrachlorohexafluorobutane, characterized in that the amount of hydrogen fluoride in the solvent used for the reaction of 1,2,3,4-tetrachlorobutane with fluorine is adjusted to a range of 10 to 60% by mass.

[0007] (3) Japanese Patent No. 5430567 (Patent Document 3) describes a method for producing 1,2,3,4-tetrachlorohexafluorobutane, which comprises: a step of synthesizing crude 1,2,3,4-tetrachlorohexafluorobutane by reacting 1,2,3,4-tetrachlorobutane with fluorine gas, introducing the reaction product into a first distillation column having a theoretical plate number of 15 or more, and obtaining a distillate component mainly containing 1,2,3,4-tetrachlorohexafluorobutane from the top of the first distillation column; and a step of introducing the distillate component into a second distillation column having a theoretical plate number of 25 or more, and obtaining purified 1,2,3,4-tetrachlorohexafluorobutane from the bottom of the second distillation column.

[0008] However, the methods described in these patent documents have the following problems.

[0009] In the method (1), when a reproduction experiment of the fluorination reaction of 1,2,3,4-tetrachlorobutane is conducted, various by-products including 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane (hereinafter referred to as 1,2,2,3,4-pentachloropentafluorobutane) as a main impurity are generated in addition to the target 1,2,3,4-tetrachlorohexafluorobutane.

[0010] In the method (2), the addition of HF to the reaction solvent allows the reaction to proceed in a low temperature range, thereby having the effect of suppressing the generation of low boiling components mainly due to the cleavage of CC bonds and the progress of excessive fluorination. However, the generation of pentachloropentafluorobutane as a by-product is not sufficiently suppressed.

[0011] In the method (3), the high boiling point components including pentachloropentafluorobutane are separated by distillation operation, and finally high-purity 1,2,3,4-tetrachlorohexafluorobutane is obtained. However, in the distillation operation, when the product purity is generally given priority, the product recovery rate per unit time is reduced. In addition, it is difficult to completely recover the target component contained in the bottom liquid mainly composed of high boiling points as a product.

[0012] That is, in the fluorination reaction step, pentachloropentafluorobutane is produced as a by-product, thereby causing a problem of reduced reaction selectivity of 1,2,3,4-tetrachlorohexafluorobutane; and in the distillation purification step, when high-boiling-point components mainly composed of pentachloropentafluorobutane are separated and removed, the bottom liquid mainly composed of pentachloropentafluorobutane containing a certain amount of 1,2,3,4-tetrachlorohexafluorobutane is treated as industrial waste, thereby causing a problem of reduced production efficiency of 1,2,3,4-tetrachlorohexafluorobutane.

[0013] Furthermore, when an additive (catalyst, HF, etc.) is used, the reaction efficiency may be improved, but the operation of separating the additive (catalyst, HF, etc.) is required after the reaction, so the overall production process may not necessarily achieve an improvement in production efficiency. Therefore, in the conventional method of producing 1,2,3,4-tetrachlorohexafluorobutane by reacting 1,2,3,4-tetrachlorobutane with fluorine, there remains a problem in terms of industrially efficiently producing the target product.

[0014] Prior art literature

[0015] Patent Literature

[0016] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-342059

[0017] Patent Document 2: Japanese Patent No. 5274449

[0018] Patent Document 3: Japanese Patent No. 5430567 Summary of the invention

[0019] Problem that the invention aims to solve

[0020] As described above, in the fluorination step of a series of processes for producing 1,2,3,4-tetrachlorohexafluorobutane from 1,3-butadiene, the following formula (1) containing pentachloropentafluorobutane is generated:

[0021] C4Cl n F 10-n (1)

[0022] (where n is an integer satisfying 5≤n≤7.) The problem of by-products shown in FIG. That is, in the fluorination reaction process, due to the by-product compound of formula (1), there is a problem of reduced reaction selectivity of 1,2,3,4-tetrachlorohexafluorobutane; and in the distillation purification process, when separating and removing the high boiling point component mainly composed of the compound of formula (1), the bottom liquid mainly composed of the compound of formula (1) containing a certain amount of 1,2,3,4-tetrachlorohexafluorobutane is treated as industrial waste, thereby reducing the production efficiency of 1,2,3,4-tetrachlorohexafluorobutane.

[0023] Therefore, an object of the present invention is to convert byproducts into target products by relatively simple operations in a series of processes for producing 1,2,3,4-tetrachlorohexafluorobutane from 1,3-butadiene, thereby improving production efficiency in the entire process.

[0024] Solutions for solving problems

[0025] The present invention provides the following solutions.

[0026] [1] A method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane, comprising: step (a) of reacting a chlorofluorobutane represented by the following formula (1) with chlorine monofluoride (ClF) to produce 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane;

[0027] C4Cl n F 10-n (1)

[0028] (In the formula, n is an integer satisfying 5≤n≤7.). [2]

[0030] The method according to [1], wherein, before the step (a), the method further comprises: a step (b) of reacting 1,2,3,4-tetrachlorobutane with fluorine gas (F2) to produce a reaction liquid containing the chlorofluorobutane represented by the formula (1). [3]

[0032] The method according to [2], wherein in the step (b), 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane is used as a solvent. [4]

[0034] The method according to any one of [1] to [3], wherein the chlorofluorobutane represented by the formula (1) contains 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane. [5]

[0036] A method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane, comprising:

[0037] Step (B) of reacting a reaction liquid containing 1,2,3,4-tetrachlorobutane with fluorine gas (F2) to produce a reaction liquid containing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane and a chlorofluorobutane represented by the following formula (1),

[0038] C4Cl n F 10-n (1)

[0039] (where n is an integer satisfying 5≤n≤7); and

[0040] In step (C), the reaction solution obtained in step (B) is reacted with chlorine monofluoride (ClF) to convert the chlorofluorobutane represented by the above formula (1) in the reaction solution obtained in step (B) into 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane. [6]

[0042] The method according to [5], wherein the chlorofluorobutane represented by the formula (1) contains 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane. [7]

[0044] The method according to [5] or [6], further comprising: step (A) of reacting 1,3-butadiene with chlorine gas (Cl2) to produce a reaction liquid containing 1,2,3,4-tetrachlorobutane, and using the reaction liquid obtained in step (A) as a raw material for step (B). [8]

[0046] The method according to any one of [1] to [4], wherein in the step (a), the reaction is carried out in the presence of hydrogen fluoride (HF). [9]

[0048] The method according to any one of [5] to [7], wherein in the step (C), the reaction is carried out in the presence of hydrogen fluoride (HF).

[0049] Effects of the Invention

[0050] According to the present invention, there are two advantageous effects in the following aspects: the organic waste liquid (high boiling point components such as by-products) obtained from the 1,2,3,4-tetrachlorohexafluorobutane production process can be converted into 1,2,3,4-tetrachlorohexafluorobutane, and 1,2,3,4-tetrachlorohexafluorobutane can be converted into hexafluoro-1,3-butadiene that can be sold as a product (an advantage of improved productivity); and the amount of waste liquid treated as industrial waste, especially fluorine-containing chlorine organic waste liquid, can be reduced (an advantage of reduced environmental load). Compared with C4Cl4 containing 1,1,2,3,4-pentachloropentafluorobutane as the main component, n F 10-n Chlorine monofluoride (ClF) obtained by the chlorofluorobutane reaction shown in (where n is an integer satisfying 5≤n≤7) can be produced in large quantities and stably by reacting a gas containing ClF3 or F2 with a gas containing Cl2 using the method described in Japanese Patent No. 6246449, and can be supplied safely for a long period of time. DETAILED DESCRIPTION

[0051] (effect)

[0052] The present inventors have found that, in a process for producing 1,2,3,4-tetrachlorohexafluorobutane, chlorine monofluoride (ClF) is allowed to act on a compound containing the following formula (1):

[0053] C4Cl n F 10-n (1)

[0054] When a crude reaction liquid of a byproduct of chlorofluorobutane represented by formula (1) or a solution containing the byproduct at a high concentration concentrated by a purification operation such as distillation is used as a reaction crude liquid of a byproduct of chlorofluorobutane represented by formula (1), the byproduct represented by formula (1) can be converted into 1,2,3,4-tetrachlorohexafluorobutane. In the present invention, by utilizing the newly discovered reaction, the byproduct is successfully converted into the target product efficiently without using additives or catalysts to suppress the side reaction, thereby achieving a reduction in byproducts without requiring the removal operation of the additives or catalysts after the reaction, and realizing a process with high production efficiency as a whole.

[0055] (Reaction of chlorofluorobutane of formula (1) with chlorine monofluoride)

[0056] The present invention provides a method for producing 1,2,3,4-tetrachlorohexafluorobutane, characterized in that it includes a step of reacting chlorofluorobutane represented by the following formula (1) with chlorine monofluoride (ClF) to produce 1,2,3,4-tetrachlorohexafluorobutane.

[0057] C4Cl n F 10-n (1)

[0058] (In the formula, n is an integer satisfying 5≤n≤7, and particularly an integer satisfying 5≤n≤6.) Examples of the chlorofluorobutane of the formula (1) include the following chlorofluorobutanes.

[0059]

[0060] Among the above-mentioned by-products, 1,1,2,3,4-pentachloropentafluorobutane is a by-product generated at a relatively high selectivity. Since such a by-product can be converted into a target product, the present invention is very useful.

[0061] Preferred reaction conditions for the reaction of chlorofluorobutane of formula (1) with chlorine monofluoride are as follows, for example.

[0062] Reaction temperature:

[0063] If the reaction temperature is low, the reactivity of chlorine monofluoride decreases, and chlorine monofluoride cannot be used efficiently for the reaction. On the other hand, if the reaction temperature is high, more energy is required, which is not economical. For these reasons, the reaction temperature is preferably 50°C to 180°C, more preferably 80°C to 150°C.

[0064] Reaction pressure:

[0065] ClF gas is highly reactive, and high pressure is not preferred for long-term stable continuous reaction. Therefore, the pressure in the reactor can be preferably set to -0.02 to 0.20 MPaG, more preferably 0 to 0.10 MPaG, as a gauge pressure. Hereinafter, the gauge pressure is referred to as "MPaG".

[0066] The preferred reaction device is composed of:

[0067] (i) When the reaction is carried out in a liquid phase, it is preferred to use 1,2,3,4-tetrachlorohexafluorobutane (boiling point: 134° C.) as the target product as the solvent. The first reason is that since the target product is used as the solvent, the step of separating the solvent after the reaction can be omitted. In addition, the second reason is that in the reaction of 1,2,3,4-tetrachlorohexafluorobutane with fluorine in the previous step described later, 1,2,3,4-tetrachlorohexafluorobutane as the target product is also used as the reaction solvent.

[0068] (ii) Materials for reaction vessels and piping and other reaction devices include stainless steel, alloys such as monel, Inconel, Hastelloy, glass, nickel, polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and the like. When the reaction is carried out under atmospheric pressure, a glass reaction vessel or a reactor made of PTFE or PFA can be used.

[0069] (iii) ClF introduction method In addition to the single-tube method, a general method such as an aeration plate type (sintered metal filter, PTFE filter) can be used to improve the contact efficiency between gas and liquid by reducing the bubble diameter, and the utilization efficiency of ClF can be improved. In addition, the utilization efficiency of ClF can be improved by combining a plurality of reactors connected in series to contact the chlorofluorobutane with the ClF gas, and introducing part or all of the unreacted ClF gas discharged from the reactor of the front stage into the reactor of the rear stage; a method of providing a stirring device in the reactor, and other general methods.

[0070] (iv) The reaction can be carried out in an intermittent manner or in a continuous manner. The intermittent manner allows for a simple reaction, while the continuous manner allows for an efficient reaction. In the case of a continuous reaction, a plurality of reactors are connected in series, ClF is introduced from the reactor on the front stage side, and the aforementioned chlorofluorobutane is introduced from the reactor on the rear stage side, thereby enabling the unreacted ClF discharged from the reactor on the front stage side to be effectively utilized in the reactor on the rear stage side.

[0071] (v) The reaction liquid (crude 1,2,3,4-tetrachlorohexafluorobutane) obtained by the reaction of the chlorofluorobutane of the formula (1) and chlorine monofluoride can be highly purified by a conventional purification operation such as distillation.

[0072] (vi) ClF gas concentration:

[0073] The ClF gas used in the reaction can be a single ClF gas, or it can be introduced as a diluted mixed gas diluted with an inert gas such as nitrogen. When the concentration of the ClF gas is high and the flow rate is also large, an overreaction occurs locally, generating trichloroheptafluorobutane, which becomes the main reason for the reduction of the reaction selectivity. In addition, in order to continuously and stably continue the reaction for a long time, the balance between the concentration of the ClF gas and the flow rate can also be adjusted to control the reactivity. In addition, when the concentration of the ClF gas is low, the production efficiency is reduced, which is disadvantageous in industry. Therefore, the concentration of the ClF gas must also be considered in terms of the balance with the flow rate, and can be preferably adjusted to 20 to 100% by volume, and more preferably adjusted to 60 to 100% by volume. The ClF gas is preferably introduced into the reactor at a flow rate of 1 to 3000 liters / hour (L / h), more preferably 1 to 1500L / h. In particular, when the reaction is carried out on an industrial scale, although it also depends on the reactor size, a large flow rate of more than 500L / h is required. In addition, as the reaction proceeds, the concentration of 1,2,3,4-tetrachlorohexafluorobutane in the reaction solution increases, which becomes a condition that easily generates excessive reactants. Therefore, the flow rate and concentration of the introduced ClF gas may be appropriately adjusted as the reaction proceeds.

[0074] (vii) Other reaction conditions:

[0075] The progress of the reaction can be confirmed by using a general analytical instrument such as gas chromatography.

[0076] 1,1,2,3,4-pentachloropentafluorobutane may be reacted alone or in the presence of a solvent.

[0077] By installing a condenser to reliquefy the vapor of the reaction liquid at the rear stage of the reactor, the loss of the reaction liquid can be reduced and the production efficiency can be improved. In addition, by utilizing the boiling point difference between the above-mentioned chlorofluorobutane and 1,2,3,4-tetrachlorohexafluorobutane as the raw materials, a device to liquefy and recover the vapor of 1,2,3,4-tetrachlorohexafluorobutane is installed at the rear stage of the reactor, and the production efficiency can be improved.

[0078] (viii) Additives:

[0079] By adding hydrogen fluoride (HF), the reactivity of chlorine monofluoride (ClF) can be improved and reacted efficiently. It is important to make HF present in the reaction solution, but since the reaction solution is heated to a temperature above the boiling point of HF, it evaporates continuously and moves to the gas phase. Therefore, by connecting a cooling condenser at the gas outlet of the reactor, HF vapor is condensed and returned to the reaction solution again, and the effect can be obtained efficiently. In addition, if HF evaporates and the HF concentration in the reaction solution decreases, the effect is reduced, so it is preferred to appropriately introduce HF midway in the reaction. HF and ClF can also be continuously introduced simultaneously, in which case, HF can be preferably adjusted to 0.003 to 0.08 times mole relative to the introduction amount of ClF, more preferably adjusted to 0.003 to 0.04 times mole.

[0080] As a preferred embodiment, for example, before the reaction of the chlorofluorobutane of formula (1) with chlorine monofluoride, a step of reacting 1,2,3,4-tetrachlorobutane with fluorine gas (F2) to produce a reaction liquid containing the chlorofluorobutane represented by the above formula (1) is carried out. The chlorofluorobutane represented by the above formula (1) is produced as a by-product when 1,2,3,4-tetrachlorohexafluorobutane is produced by reacting 1,2,3,4-tetrachlorobutane with fluorine gas (F2). The chlorofluorobutane of formula (1) can be separated or concentrated from the reaction liquid obtained by the reaction with the fluorine gas by distillation or the like, and then the reaction with chlorine monofluoride in the next step can be carried out, or the reaction liquid obtained by the reaction with fluorine gas can be directly used to carry out the reaction with chlorine monofluoride in the next step. In the former case (with separation and concentration), 1,2,3,4-tetrachlorohexafluorobutane can be obtained efficiently. In the latter case, the yield is reduced due to the formation of excess reactant (C4Cl3F7), but the step of separating or concentrating the chlorofluorobutane of formula (1) by distillation can be omitted.

[0081] Preferred reaction conditions for the reaction of 1,2,3,4-tetrachlorobutane with fluorine gas (F2) are as follows, for example.

[0082] Solvent:

[0083] In addition to 1,2,3,4-tetrachlorohexafluorobutane, chlorocarbons exemplified by tetrachloromethane and hexachloroethane, chlorofluorocarbons exemplified by 1,1,2-trichloro-1,2,2-trifluoroethane, 1,1,2,2-tetrachloro-1,2-difluoroethane, and the like can be used.

[0084] Reaction temperature:

[0085] When the reaction temperature is low, the utilization efficiency of fluorine gas decreases, and when the reaction temperature is high, a decomposition reaction accompanied by the cleavage of CC bonds may occur, which may become a major factor in reducing the reaction yield. For these reasons, it can be preferably set to 10 to 100°C, and more preferably set to 20 to 70°C.

[0086] Reaction pressure:

[0087] Fluorine gas is highly reactive, and high pressure is not preferred in order to stably and continuously continue the reaction for a long period of time. Therefore, the pressure in the reactor can be preferably set to -0.02 to 0.20 MPaG, more preferably 0 to 0.10 MPaG, as a gauge pressure.

[0088] Fluorine gas concentration:

[0089] The fluorine gas used in the reaction may be a single fluorine gas, or may be introduced as a diluted mixed gas diluted with an inert gas such as nitrogen. When the concentration of fluorine gas is high, a decomposition reaction accompanied by the breakage of the CC bond may occur, which is the main reason for the reduction in reaction yield. In addition, in order to stably and continuously continue the reaction for a long time, the concentration of fluorine gas may also be adjusted to control the reactivity. In addition, when the concentration of fluorine gas is low, the production efficiency is reduced, which is disadvantageous in industry. Therefore, the concentration of fluorine gas may preferably be adjusted to 20 to 80% by volume, and more preferably adjusted to 40 to 70% by volume.

[0090] The preferred reaction device is composed of:

[0091] When the reaction is carried out in a liquid phase, it is preferred to use 1,2,3,4-tetrachlorohexafluorobutane (boiling point: 134° C.), which is the target product, as a solvent. The reason for this is that the target product is used as a solvent, so that the step of separating the solvent after the reaction can be omitted.

[0092] Materials for reaction vessels and pipes include stainless steel, alloys such as monel, inconel, hastelloy, nickel, etc. A reactor made of PTFE may be used as long as the concentration of fluorine gas is adjusted to 20% or less and the reaction is performed under atmospheric pressure.

[0093] Regarding the method for introducing fluorine gas, general methods such as a method of connecting a plurality of reactors in series in combination, bringing 1,2,3,4-tetrachlorobutane and / or a reaction intermediate in which hydrogen atoms of 1,2,3,4-tetrachlorobutane are partially replaced by fluorine atoms into contact with fluorine gas, and introducing part or all of the unreacted fluorine gas discharged from the reactor of the front stage into the reactor of the rear stage; and a method of providing a stirring device in the reactor, can improve the utilization efficiency of fluorine gas.

[0094] The crude 1,2,3,4-tetrachlorohexafluorobutane obtained by the reaction of 1,2,3,4-tetrachlorobutane and fluorine can be highly purified by a common purification operation such as distillation.

[0095] Application example of the reaction of chlorofluorobutane of formula (1) with chlorine monofluoride in a method for producing 1,2,3,4-tetrachlorohexafluorobutane using 1,3-butadiene as a starting material via 1,2,3,4-tetrachlorobutane (hereinafter referred to as the butadiene method)

[0096] Chlorofluorobutane of formula (1) is a byproduct in the process for producing 1,2,3,4-tetrachlorohexafluorobutane (butadiene process), so the reaction of chlorofluorobutane of formula (1) with chlorine monofluoride can convert the byproduct into the target product, which is useful. Specifically, 1,2,3,4-tetrachlorohexafluorobutane can be efficiently produced by an integrated process including the following series of steps.

[0097] A method comprising:

[0098] Step (A), reacting 1,3-butadiene with chlorine (Cl2) to produce a reaction solution containing 1,2,3,4-tetrachlorobutane;

[0099] Step (B) of reacting the reaction solution containing 1,2,3,4-tetrachlorobutane obtained in step (A) with fluorine gas (F2) to produce a reaction solution containing 1,2,3,4-tetrachlorohexafluorobutane and a chlorofluorobutane represented by the following formula (1),

[0100] C4Cl n F 10-n (1)

[0101] (where n is an integer satisfying 5≤n≤7); and

[0102] In step (C), the reaction solution obtained in step (B) is reacted with chlorine monofluoride (ClF) to convert the chlorofluorobutane represented by the above formula (1) in the reaction solution obtained in step (B) into 1,2,3,4-tetrachlorohexafluorobutane.

[0103] Regarding step (A), it is well known in the art that 1,3-butadiene is reacted with chlorine (Cl2) to obtain a reaction solution containing 1,2,3,4-tetrachlorobutane. However, in the series of processes of the present invention, preferred reaction conditions are as follows, for example.

[0104] Reaction temperature:

[0105] It is preferably -20 to 40°C, more preferably -20 to 20°C.

[0106] Reaction pressure:

[0107] It is preferably 0 to 1.5 MPaG, more preferably 0 to 0.3 MPaG.

[0108] Reaction solvent:

[0109] Specific examples of preferred solvents include chloroform, dichloromethane, 1,2,3,4-tetrachlorohexafluorobutane, etc. When 1,2,3,4-tetrachlorohexafluorobutane is used as the solvent, there is an advantage that the product does not need to be separated from the solvent in the subsequent fluorination reaction step.

[0110] The preferred reaction device is composed of:

[0111] (i) Materials for reaction vessels and piping and other reaction devices include stainless steel, alloys such as Inconel, Hastelloy, and Monel, glass, polytetrafluoroethylene (PTFE), and perfluoroalkoxyalkane (PFA). When the reaction is carried out under atmospheric pressure, reaction vessels made of glass, PTFE, or PFA can be used.

[0112] (ii) The reaction of chlorine and 1,3-butadiene is preferably carried out by supplying chlorine gas and 1,3-butadiene gas into a reaction solvent and bringing them into contact. The amount of chlorine gas introduced is preferably 2.0 to 3.0 times the mole of the 1,3-butadiene gas, more preferably 2.0 to 2.4 times the mole.

[0113] The reaction conditions and reaction apparatus of steps (B) and (C) are as described above in relation to the "reaction of chlorofluorobutane of formula (1) with chlorine monofluoride". When steps (A) to (C) are performed continuously, the following conditions are particularly preferred from the perspective of improving the yield of the target product 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane.

[0114] Step (A): temperature (-20 to 20°C), pressure (0 to 0.3 MPaG), and other conditions (the Cl2 introduction flow rate is preferably 2.0 to 2.4 times the molar amount of 1,3-butadiene).

[0115] Step (B): temperature (20 to 70°C), pressure (0 to 0.1 MPaG), and other conditions (the F2 gas concentration in the diluted mixed gas is preferably 40 to 70% by volume).

[0116] Step (C): temperature (80 to 150° C.), pressure (0 to 0.1 MPaG), and other conditions (the ClF gas concentration in the diluted mixed gas is preferably 50 to 80% by volume).

[0117] (Other application examples)

[0118] 1,2,3,4-tetrachlorobutane can be obtained not only by reacting 1,3-butadiene with chlorine, but also by distilling a byproduct when producing chloroprene rubber and reacting 3,4-dichloro-1-butene, an intermediate when producing chloroprene rubber, with one molecule of chlorine. The production method of the present invention is related to the production of chloroprene rubber, and the raw materials can be easily obtained, so it is excellent in mass productivity.

[0119] (About the use of inert gas)

[0120] Examples of the inert gas used in the present invention include nitrogen, helium, neon, argon, etc. The concentration of the inert gas is as described in the above-mentioned items.

[0121] Example

[0122] The present invention will be specifically described based on the following examples, but the scope of the present invention is not limited to the following examples. The following examples are carried out according to the following reaction scheme.

[0123]

[0124] (Example 1: Chlorination reaction)

[0125] 3267 g of the final target 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) as a reaction solvent was placed in a 4L SUS reactor equipped with a gas inlet and a gas outlet connected to a -20°C condenser, and the reactor temperature was set to 50°C. Then, 1,3-butadiene gas (C4H6) and chlorine gas (Cl2) were blown into the liquid phase from the gas inlet at flow rates of 11.8 liters / hour (L / h) and 31.0 L / h, respectively, and the reaction was stopped after 9.5 hours. Nitrogen was blown into the liquid phase from the gas inlet to discharge the chlorine dissolved in the reaction solution, then the reactor was opened and the reaction solution was taken out. The reaction solution was analyzed, and 1,2,3,4-tetrachlorobutane (C4H6Cl4) was obtained with a yield of 89% (yield 872 g).

[0126] (Example 2: Fluorination reaction)

[0127] 3000 g of the final target 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) as a solvent and 800 g of 1,2,3,4-tetrachlorobutane (C4H6Cl4) as a raw material were added to a 3L SUS reactor equipped with a gas inlet and a gas outlet, and the reactor temperature was set to 60°C. Next, 30% by volume fluorine gas (F2) diluted with nitrogen (N2) was introduced into the liquid phase at a flow rate of 60.0 L / h for 20 hours from the gas inlet. The reactor temperature was changed to 35°C, and 50% by volume fluorine gas diluted with nitrogen was introduced into the liquid phase at 24.0 L / h for 34 hours, and the reaction was stopped. Nitrogen was blown into the liquid phase from the gas inlet, and after the fluorine gas dissolved in the reaction solution was discharged, the reactor was opened and the reaction solution was taken out. The reaction solution was analyzed, and the result showed that it contained 92% by weight of 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6). In addition, as a by-product, 6% by weight of 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5) was contained.

[0128] Using 2400 g of the reaction liquid, by distillation (filling material: Heli-Pack No. 3 / HETP: 48 mm, tower height: 50 cm, theoretical number of plates: 10.4 plates), 2086 g of a distillate containing 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) with a purity of more than 98 wt% and 242 g of a high-boiling distillate containing 57 wt% of 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5) were obtained.

[0129] (Example 3: Cl-F exchange reaction)

[0130] In a 200ml PFA reactor equipped with a gas inlet and a gas outlet, 200g of a high boiling distillate containing 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5) obtained by the distillation of Example 2 was put, and a cooling condenser at -20°C was connected to the gas outlet side of the reactor, and the reactor was heated to 130°C. Then, 50% by volume of chlorine monofluoride gas (ClF) diluted with nitrogen (N2) was introduced into the liquid phase at a flow rate of 3.6L / h for 5.5 hours, and the reaction was stopped. Nitrogen was blown into the liquid phase from the gas inlet, and after the chlorine monofluoride gas dissolved in the reaction solution was discharged, the reactor was opened and 184g of the reaction solution was taken out. The reaction solution was analyzed, and the concentration of 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) was 96% by weight.

[0131] (Example 4: Cl-F exchange reaction)

[0132] 200g of 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5) with a purity of 97% was added to a 200ml PFA reactor equipped with a gas inlet and a gas outlet, and a 0°C trap was set on the gas outlet side of the reactor. Furthermore, a -20°C cooling condenser was connected to the gas outlet side of the trap, and the reactor was heated to 130°C. Next, 50% by volume chlorine monofluoride gas (ClF) diluted with nitrogen (N2) was introduced at a flow rate of 6.0L / h for 3.5 hours, and then the reactor temperature was changed to 100°C. After the 50% by volume chlorine monofluoride gas was reduced to a flow rate of 1.8L / h and introduced for 7.0h, the reaction was stopped. Nitrogen was blown in from the gas inlet to discharge the chlorine monofluoride gas dissolved in the reaction solution, and then the reactor was opened to take out 174g of the reaction solution. The reaction solution was analyzed and found to have a concentration of 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) of 98%.

[0133] (Example 5: Fluorination reaction)

[0134] 3000 g of tetrachloromethane (CCl4) as a solvent and 800 g of 1,2,3,4-tetrachlorobutane (C4H6Cl4) as a raw material were added to a 3L SUS reactor equipped with a gas inlet and a gas outlet, and the reactor temperature was set to 60°C. Next, 30% by volume fluorine gas (F2) diluted with nitrogen (N2) was introduced into the liquid phase at a flow rate of 60.0 L / h for 20 hours from the gas inlet. The reactor temperature was changed to 35°C, and 50% by volume fluorine gas diluted with nitrogen was introduced into the liquid phase at 24.0 L / h for 34 hours, and the reaction was stopped. Nitrogen was blown into the liquid phase from the gas inlet, and after the fluorine gas dissolved in the reaction solution was discharged, the reactor was opened and the reaction solution was taken out. After the solvent was removed by reduced pressure distillation from the reaction solution, it was analyzed and the result showed that it contained 75% by weight of 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6). In addition, as a by-product, 17% by weight of 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5) was contained.

[0135] (Example 6: Cl-F exchange reaction)

[0136] In a 200ml PFA reactor equipped with a gas inlet and a gas outlet, 200g of a liquid containing 17% by weight of 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5) and 75% by weight of 1,2,3,4-tetrachlorohexafluorobutane obtained in the reaction of Example 5 was put into the reactor. A cooling condenser at -20°C was connected to the gas outlet side of the reactor, and the reactor was heated to 130°C. Then, 50% by volume of chlorine monofluoride gas (ClF) diluted with nitrogen (N2) was introduced at a flow rate of 1.8L / h for 3.5 hours, and the reaction was stopped. Nitrogen was blown into the gas inlet, and after the chlorine monofluoride gas dissolved in the reaction solution was discharged, the reactor was opened and 188g of the reaction solution was taken out. The reaction solution was analyzed, and the concentration of 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) was 96% by weight. In addition, the reaction liquid contains 1,2,3-trichloro-1,1,2,3,4,4,4-heptafluorobutane (C4Cl3F7) and 1,2,4-trichloro-1,1,2,3,3,4,4-heptafluorobutane (C4Cl3F7).

[0137] (Example 7: Cl-F exchange reaction)

[0138] 1,2,3,4-tetrachlorohexafluorobutane was synthesized by the same method as in Example 5, and the reaction liquid was taken out. 4130 g of the reaction liquid was used to distill off the solvent tetrachloromethane by distillation (filling material: Heli-Pack No. 3 / HETP: 48 mm, tower height: 50 cm, theoretical plate number: 10.4 plates). Next, a liquid containing 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) and 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5) was distilled off to obtain 112 g of a bottom liquid in which the high boiling point component was concentrated. The bottom liquid was analyzed, and the result showed that it contained 7% by weight of 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) and 41% by weight of 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5). It is also known that, in addition to these, 20% by weight of 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane (C4Cl6F4) is also contained. 105g of the kettle residue is put into a 100ml PFA reactor equipped with a gas inlet and a gas outlet, a cooling condenser of -20°C is connected to the gas outlet side of the reactor, and the reactor is heated to 130°C. Then, 50% by volume chlorine monofluoride gas (ClF) diluted with nitrogen (N2) is introduced into 2.0 hours with a flow rate of 1.8L / h, and a part of the reaction solution is collected for analysis. Then, the reaction solution is heated again, and 50% by volume chlorine monofluoride gas diluted with nitrogen is introduced into 2.0 hours with a flow rate of 1.8L / h, and a part of the reaction solution is collected in the same way for analysis. Furthermore, the reaction solution is heated again, and 50% by volume chlorine monofluoride gas diluted with nitrogen is introduced into 3.0 hours with a flow rate of 1.8L / h, and the reaction is stopped. Nitrogen gas was blown in from the gas inlet to discharge the chlorine monofluoride gas dissolved in the reaction liquid, and then the reactor was opened to take out 93 g of the reaction liquid. The results of the analysis of the reaction liquid and the results of the analysis during the reaction are shown in Table 1 below.

[0139] [Table 1]

[0140] Table 1

[0141]

[0142] (Example 8: Cl-F exchange reaction)

[0143] 1,2,3,4-tetrachlorohexafluorobutane was synthesized by the same method as in Example 2, and the reaction liquid was taken out. The reaction liquid was used for distillation under reduced pressure (filling material: Heli-Pack No. 3 / HETP: 48 mm, tower height: 100 cm, theoretical plate number: 20.8 plates) to distill a liquid containing 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6). The bottom liquid was analyzed, and the result showed that it contained 8% by weight of 1,2,3,4-tetrachlorohexafluorobutane, 54% by weight of 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5), and 4% by weight of 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane. In a 250ml PFA reactor equipped with a gas inlet and a gas outlet, 250g of the still residue is dropped, and a cooling condenser of -20°C is connected to the gas outlet side of the reactor, and the reactor is heated to 130°C. Then, after 50% by volume chlorine monofluoride gas (ClF) diluted with nitrogen (N2) is introduced into 0.5 hour with a flow rate of 1.8L / h, a part of the reaction solution is collected for analysis. Then, the reaction solution is heated again, and after 50% by volume chlorine monofluoride gas diluted with nitrogen is introduced into 1.0 hour with a flow rate of 1.8L / h, a part of the reaction solution is collected in the same manner for analysis. And then, the reaction solution is heated again, and after 50% by volume chlorine monofluoride gas diluted with nitrogen is introduced into 11.0 hours with a flow rate of 1.8L / h, the reaction is stopped. Nitrogen is blown into the gas inlet, and after the chlorine monofluoride gas dissolved in the reaction solution is discharged, the reactor is opened and 215g of the reaction solution is taken out. The results of analyzing the reaction solution are shown in Table 2 below together with the results of analysis during the reaction.

[0144] [Table 2]

[0145] Table 2

[0146]

[0147] As shown in the above examples, according to the present invention, the organic waste liquid (high boiling point components such as byproducts) obtained from the 1,2,3,4-tetrachlorohexafluorobutane production process can be valuable converted into 1,2,3,4-tetrachlorohexafluorobutane. Specifically, by fluorination of 1,2,3,4-tetrachlorobutane (C4H6Cl4) using fluorine gas (F2), 1,1,2,3,4-pentachloropentafluorobutane (C4Cl5F5) and 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane (C4Cl6F4) produced as byproducts in addition to the target 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6) are further reacted with ClF, thereby converting it into the target 1,2,3,4-tetrachlorohexafluorobutane (C4Cl4F6).

[0148] (Example 9: Cl-F exchange reaction)

[0149] As the first reactor and the second reactor, a SUS304 reactor with a heating jacket and an internal volume of 25 L was used. A -25°C cooling condenser was set at the gas outlet of the first reactor, and the gas outlet of the cooling condenser was connected to the gas inlet of the second reactor. Furthermore, a -25°C cooling condenser was set at the gas outlet of the second reactor. In addition, the liquid outlet of the second reactor was connected to the liquid inlet of the first reactor. Furthermore, the liquid outlet of the first reactor was connected to the reaction liquid receiving tank.

[0150] 29.1 kg of a raw material liquid was added to each of these reactors. The raw material liquid contained 1 wt% of 1,1,2,3,4,4-hexachlorotetrafluorobutane, 56 wt% of 1,1,2,3,4-pentachloropentafluorobutane, and 35 wt% of 1,2,3,4-tetrachlorohexafluorobutane, and was a part of the high boiling point distillate obtained by the same method as in Example 2 after distillation.

[0151] The liquid inside the first reactor and the second reactor was adjusted to 105°C, and a mixed gas containing 97% by volume of chlorine monofluoride gas (ClF) and 3% by volume of hydrogen fluoride gas (HF) was introduced at a flow rate of 11.1 L / h to start the reaction. After 80 hours of reaction, the continuous supply of the aforementioned raw material liquid was started at a flow rate of 0.19 L / h from the liquid inlet of the second reactor. While the ClF gas concentration in the outlet gas of the cooling condenser at the rear section of the second reactor was quantitatively analyzed by FT-IR, the reaction was continued for 120 hours, and the utilization rate of ClF was stabilized at 88%. Furthermore, the reaction liquid flowing out of the liquid outlet of the first reactor at this time was analyzed, and the composition of the reaction liquid was: 0% by weight of 1,1,2,3,4,4-hexachlorotetrafluorobutane, 24% by weight of 1,1,2,3,4-pentachloropentafluorobutane, and 66% by weight of 1,2,3,4-tetrachlorohexafluorobutane.

[0152] (Example 10: Cl-F exchange reaction)

[0153] Using the same reaction apparatus as in Example 9, 29.1 kg of the raw material liquid was added to each of the first reactor and the second reactor. The raw material liquid used was the same as that used in Example 9.

[0154] The liquid inside the first reactor and the second reactor was adjusted to 105°C, and chlorine monofluoride gas (ClF) was introduced at a flow rate of 10.8 L / h to start the reaction. After 80 hours of reaction, the continuous supply of the aforementioned raw material liquid was started at a flow rate of 0.19 L / h from the liquid inlet of the second reactor. While using FT-IR to quantitatively analyze the ClF gas concentration in the outlet gas of the cooling condenser at the rear section of the second reactor, the continuous reaction was carried out for 120 hours, and the utilization rate of ClF was stabilized at 63%. Furthermore, the reaction liquid flowing out of the liquid outlet of the first reactor at this time was analyzed, and the composition of the reaction liquid was: 0% by weight of 1,1,2,3,4,4-hexachlorotetrafluorobutane, 34% by weight of 1,1,2,3,4-pentachloropentafluorobutane, and 57% by weight of 1,2,3,4-tetrachlorohexafluorobutane.

Claims

1. A method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane, comprising: Step (a), reacting chlorofluorobutane represented by the following formula (1) with chlorine monofluoride (ClF) to produce 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane, C4Cl n F 10-n (1) In the formula, n is an integer satisfying 5≤n≤7.

2. The method according to claim 1, wherein: Prior to the step (a), the method further comprises a step (b) of reacting 1,2,3,4-tetrachlorobutane with fluorine gas (F2) to produce a reaction liquid containing the chlorofluorobutane represented by the formula (1).

3. The method according to claim 2, wherein: In the step (b), 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane is used as a solvent.

4. The method according to any one of claims 1 to 3, wherein: The chlorofluorobutane represented by the formula (1) contains 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane.

5. A method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane, comprising: Step (B) of reacting a reaction liquid containing 1,2,3,4-tetrachlorobutane with fluorine gas (F2) to produce a reaction liquid containing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane and a chlorofluorobutane represented by the following formula (1), C4Cl n F 10-n (1) Wherein n is an integer satisfying 5≤n≤7; and Step (C) is to react the reaction solution obtained in step (B) with chlorine monofluoride (ClF) to convert the chlorofluorobutane represented by the formula (1) in the reaction solution obtained in step (B) into 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane.

6. The method according to claim 5, wherein: The chlorofluorobutane represented by the formula (1) contains 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane.

7. The method according to claim 5 or 6, further comprising: In step (A), 1,3-butadiene is reacted with chlorine gas (Cl2) to produce a reaction liquid containing 1,2,3,4-tetrachlorobutane, and the reaction liquid obtained in step (A) is used as a raw material in step (B).

8. The method according to any one of claims 1 to 3, wherein: In the step (a), the reaction is carried out in the presence of hydrogen fluoride (HF).

9. The method according to claim 4, wherein: In the step (a), the reaction is carried out in the presence of hydrogen fluoride (HF).

10. The method according to claim 5 or 6, wherein: In the step (C), the reaction is carried out in the presence of hydrogen fluoride (HF).

11. The method according to claim 7, wherein: In the step (C), the reaction is carried out in the presence of hydrogen fluoride (HF).

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