Method for producing chlorofluorobutane (CFB)

Abstract

To provide a method for producing chlorofluorobutane (CFB) by dimerizing trichloroethylene (TCE) to generate chlorinated butadiene and fluorinating the hydrogen atoms of this chlorinated butadiene.　Trichloroethylene (TCE) is dimerized at a temperature of 100°C or more in the presence of a free radical generator using a dimer represented by formula (1) from TCE as a solvent. Hexachlorobutadiene (C4Cl6) is produced by chlorination and dehydrochlorination from the dimer, and the hexachlorobutadiene is fluorinated to produce chlorofluorobutane (CFB).

Description

Method for producing chlorofluorobutane (CFB)

[0001] The present invention relates to a method for producing chlorofluorobutane (CFB), and more particularly to a method for producing CFB by dimerizing trichloroethylene (TCE) to produce chlorinated butadiene and fluorinating the hydrogen atoms of the chlorinated butadiene.

[0002] TCE is a by-product of various synthetic reactions, but its environmental impact is a concern. Therefore, there is a need for a method to effectively utilize TCE without allowing it to accumulate. It is known that TCE dimerizes in the presence of a free radical generator to produce chlorinated butylenes (Patent Document 1). This method is useful for forming a chlorinated butane skeleton or a chlorinated butadiene skeleton from TCE. However, the method disclosed in Patent Document 1 is small-scale (using only 5 g of TCE), and further improvement is required for mass production of the dimer.

[0003] On the other hand, in recent years, etching gases with low environmental impact, such as hexafluorobutadiene (perfluorobutadiene, HFB), have been used, and a mass production method thereof has also been proposed (Patent Document 2). A method for producing HFB by fluorinating chlorinated butane or chlorinated butadiene has been investigated.

[0004] Non-Patent Document 1 describes the synthesis of 1,2,3,4-tetrachloro-1,3-butadiene with ClF ３ and ClF in succession to carry out a fluorination reaction to produce chlorofluorobutane. ４ Cl ４ F ６ It is also disclosed that hexafluorobutadiene (perfluorobutadiene, HFB) can be produced by dechlorination of fluorobutadiene.

[0005] Patent No. 3951331 Patent No. 5005681

[0006] J.Muray., J. Chem. Soc., p1884 (1959)

[0007] A first object of the present invention is to provide a method for efficiently producing a TCE dimer. A second object of the present invention is to provide a series of integrated processes for producing chlorinated butane or chlorinated butadiene from TCE and further fluorinating the chlorinated butane or fluorinated butadiene.

[0008] The present invention provides the following: [1] A compound obtained by converting trichloroethylene (TCE) into a compound represented by the following formula (1):

[0013] A method for producing a dimer of TCE represented by the following formula (1): Hexachlorobutadiene (C) is produced by chlorination and dehydrochlorination of a dimer of trichloroethylene (TCE) represented by the formula: ４ Cl ６ ), comprising reacting a dimer of TCE with chlorine gas (Cl) in the presence of a Lewis acid catalyst. ２ [5] The method according to [4], wherein the reaction is carried out at a temperature of 30 to 200° C. [6] The method according to [4], wherein the Lewis acid catalyst is FeCl ３ [7] A method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane from trichloroethylene (TCE), comprising: (A) reacting trichloroethylene (TCE) with a compound represented by the following formula (1): wherein step (A) comprises dimerizing TCE at a temperature of 100°C or higher in the presence of a free radical generator using the dimer represented by formula (1) as a solvent; and (B) producing hexachlorobutadiene (C) from the TCE dimer represented by formula (1) by chlorination and dehydrochlorination. ４ Cl ６ ), wherein step (B) is a step of preparing a fluorine-containing fluoride (F) by using FeCl as a reaction catalyst. ３ In the presence of TCE dimer and chlorine gas (Cl２ (C) hexachlorobutadiene (C ４ Cl ６ (D) reacting the fluorinated product obtained in step (C) with chlorine monofluoride (ClF) to produce 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane. [8] The method according to claim 1, wherein the fluorinated product obtained in step (C) further contains 1,1,1,2,3,4,4-heptachloro-1,2,3-trifluorobutane (C ４ Cl ７ F ３ ) and 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane (C ４ Cl ５ F ５ The method according to [7], comprising:

[0009] According to the present invention, it is possible to efficiently produce a TCE dimer. Furthermore, according to the present invention, it is possible to efficiently produce chlorinated butane or chlorinated butadiene from TCE, which is relatively easily available. Furthermore, the obtained chlorinated butane or chlorinated butadiene can be fluorinated to produce fluorinated butane or fluorinated butadiene, so that an etching gas with a low environmental impact, such as HFB, can be produced in large quantities at low cost through a series of integrated processes.

[0010] (Action) It is known that in the dimerization reaction of trichloroethylene (TCE), a reaction temperature of 100°C or higher is effective for efficiently progressing the free radical reaction (Patent Document 1). On the other hand, since the boiling point of TCE is 87°C, in order to raise the reaction temperature to 100°C or higher, it was necessary to carry out the pressurized reaction in a sealed pressure vessel. The present inventors have proposed a method for producing a dimer of trichloroethylene (TCE) by the reaction of the following formula (1): Taking note of the fact that the boiling point of the TCE dimer, expressed as follows, is 205°C (calculated value), and by using this dimer as the reaction solvent, we succeeded in carrying out the reaction at temperatures above 100°C without using a pressure vessel. Because the dimer, which is the product, is the reaction solvent, the product can be easily purified by removing the raw material TCE.

[0011] The fluorination of the TCE dimer was carried out using fluorine gas (F ２ When a method of reacting chlorine gas (Cl) with TCE dimers was tried, the dimers were first reacted with chlorine gas (Cl) in the presence of a catalyst. ２ ) to produce hexachlorobutadiene (HCB), and then F is added to this HCB. ２ By reacting with 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane (C ４ Cl ６ F ４ It was found that the obtained C ４ Cl ６ F ４ is reacted with ClF to produce 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane (C ４ Cl ４ F ６ ) and C ４ Cl ４ F ６ can be dechlorinated to produce hexafluorobutadiene (perfluorobutadiene, HFB).

[0012] (Dimerization Reaction of Trichloroethylene (TCE)) In the present invention, the dimerization reaction can be carried out by heating to a temperature of 100°C or higher under atmospheric pressure, so a pressure-resistant container is not required. The reaction temperature is preferably 100 to 200°C, more preferably 120 to 150°C. The product contains unreacted TCE and its dimer, but the TCE can be easily removed by distillation. The reaction product from which TCE has been removed essentially consists of TCE dimer and can be used as is in the next step.

[0013] (Chlorination and dehydrochlorination reaction of TCE dimer) In the present invention, hexachlorobutadiene (C ４ Cl ６ This step involves the reaction of a TCE dimer with chlorine gas (Cl) in the presence of a Lewis acid catalyst. ２ ) and hexachlorobutadiene (C ４ Cl ６ By using AlCl as an intermediate, the position to be fluorinated in the next step can be limited, and the selectivity of the target product can also be increased. The temperature for the chlorination and dehydrochlorination reaction of the TCE dimer is preferably 30 to 200°C, more preferably 50 to 200°C, and even more preferably 120 to 150°C. Examples of Lewis acid catalysts include AlCl ３ , SnCl ４ , TiCl ４ , FeCl ３ , ZnCl ２ , AlF ３ , MgF ２ , CaF ２ , CrF ３ , ZrF ４ FeCl ３ is most preferred.

[0014] (Hexachlorobutadiene (C ４ Cl ６ In the present invention, hexachlorobutadiene (C ４ Cl ６ ) is fluorinated with a fluorinating agent to produce a fluorinated product containing 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane. In this reaction, in addition to 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane, 1,1,1,2,3,4,4-heptachloro-1,2,3-trifluorobutane (C ４ Cl ７ F ３ ) and 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane (C ４ Cl ５ F ５) is produced and is contained in the fluorination product, but both compounds can be converted into the target compound 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane (C ４ Cl ４ F ６ ), so there is no need to separate it by purification.

[0015] The fluorinating agent is not particularly limited, but may be fluorine gas (F ２ ), chlorine trifluoride (ClF ３ From the viewpoint of the selectivity of 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane, fluorine gas (F ２ ) is preferred.

[0016] (Reaction of fluorination products containing 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane with chlorine monofluoride (ClF)) The reaction can be carried out by contacting 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane with ClF. The reaction temperature is preferably 50 to 200°C, more preferably 80 to 150°C. In this reaction, 1,1,1,2,3,4,4-heptachloro-1,2,3-trifluorobutane (C ４ Cl ７ F ３ ) and 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane (C ４ Cl ５ F ５ ) and the target compound 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane (C ４ Cl ４ F ６ The advantage of adopting this process is that it is possible to convert 1,1,1,2,3,4,4-heptachloro-1,2,3-trifluorobutane (C ４ Cl ７ F ３ ) and 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane (C ４ Cl ５ F ５) can be converted into tetrachlorohexafluorobutane, eliminating the need for a purification step. In other words, reaction conditions that increase the selectivity for the target product include introducing ClF at a low flow rate and allowing 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane and ClF to react uniformly and mildly. Specifically, the following conditions are desirable. <Reaction Conditions> (a) When performing a laboratory-scale reaction using 20 to 1,000 g of raw material liquid, for example, the ClF flow rate is preferably 0.6 to 30 L / hr, more preferably 0.6 to 12 L / hr. (b) It is preferable to use an aeration plate such as a sintered metal filter in the ClF bubbling nozzle to miniaturize the bubbles. More preferably, a sintered metal filter with a filter diameter of 5 to 500 μm is used. (c) The reactor may be made of stainless steel, alloys such as Monel, Inconel, and Hastelloy, glass, nickel, polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), etc. In order to ensure a sufficient residence time, it is preferable to use a vertical reactor.

[0017] (Dechlorination Reaction of 1,2,3,4-Tetrachloro-1,1,2,3,4,4-Hexafluorobutane) Hexafluorobutadiene (HFB) can be produced by dechlorinating 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane. While this reaction is well known in the art, the present invention enables inexpensive mass production of HFB from TCE by incorporating new findings in a series of intermediate steps. Reaction conditions include, for example, the following: Kind of metal used as reaction catalyst: Magnesium, zinc, cadmium, aluminum, copper, sodium, lithium, etc. can be used, with magnesium and zinc being preferred. Nature of metal used as reaction catalyst: Granular or powder form is preferred. Reaction solvent: An organic solvent or a mixed solvent of an organic solvent and water can be used. Water alone can also be used. The organic solvent is preferably an alcohol, and examples of usable solvents include methanol, ethanol, isopropyl alcohol, and octanol. Reaction temperature: preferably 20 to 150°C, more preferably 30 to 90°C.

[0018] The present invention will be specifically described with reference to the following examples, but the scope of the present invention is not limited to the following examples. The following examples were carried out according to the following reaction scheme.

[0019]

[0020] Example 1: Dimerization of TCE (2C ２ Cl ３ H → C ４ Cl ６ H ２ )) In a 300 ml glass flask connected to a dropping funnel and a condenser, the dimer of TCE represented by the formula (1) (C ４ Cl ６ H ２ 75 g of toluene was added to the reactor, 25 g of TCE was added as a raw material, and 0.5 g of di-tert-butyl peroxide was added as a free radical generator. The reactor was heated to 140°C, and the TCE was refluxed for 20 hours (hr). Analysis of the reaction solution revealed that TCE dimer (C) was produced from TCE in a yield of 53%. ４ Cl ６ H ２ TCE can be separated from the reaction mixture using an evaporator or the like, and the product is a TCE dimer (C ４ Cl ６ H ２ ) can be recovered.

[0021] Comparative Example 1: Dimerization of TCE (2C ２ Cl ３ H → C ４ Cl ６ H ２ )) 30 g of TCE was placed in a 50 ml sealed container made of fluororesin, and 0.2 g of di-tert-butyl peroxide was added as a free radical generator without using a solvent. The reactor was heated to 150°C and the reaction was carried out for 5 hours (hr). Analysis of the reaction solution revealed the presence of a TCE dimer (C ４ Cl ６ H ２ ) was obtained in a yield of 50%.

[0022] Comparing Example 1 and Comparative Example 1, it was found that the present invention enabled the production of TCE dimer in a good yield (53%) without the use of a sealed pressure vessel. The TCE dimer could be easily purified by removing unreacted raw materials by distillation. Since the present invention does not require the use of a pressure vessel, it was found to be suitable as one step in a continuous integrated process.

[0023] Example 2: Chlorination and dehydrochlorination reaction (C ４ Cl ６ H ２ → C ４ Cl ６ ) In a 500 ml glass flask connected to a condenser, TCE dimer (C ４ Cl ６ H ２ ) was added, and FeCl was added as a reaction catalyst. ３ The reactor was heated to 90°C and chlorine gas (Cl ２ ) was bubbled through the reactor at a rate of 6 liters / hour (L / hr), and the reaction was stopped after 8 hours. Thereafter, the reactor heating temperature was changed to 150°C, and heating was continued for 4 hours. Nitrogen gas was blown in through the gas inlet to expel the chlorine gas dissolved in the reaction solution, and then the reactor was opened and the reaction solution was taken out. Analysis of the reaction solution by GC showed that hexachlorobutadiene (C) was produced in a yield of 93%. ４ Cl ６ ) was obtained.

[0024] Example 3: Fluorine gas (F ２ Fluorination reaction with hexachlorobutadiene (C) ４ Cl ６ ) 450 g was added, and the mixture was cooled with ice to give a solution of 20% by volume of fluorine gas (F ２) was bubbled through the reaction mixture at a flow rate of 24 L / hr for 17 hours. Nitrogen was then bubbled through the reaction mixture at the same flow rate for 1 hour, yielding 544 g of a reaction mixture. NMR analysis of this reaction mixture revealed that it contained 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane, which was produced by fluorination of the unsaturated bonds of hexachlorobutadiene, in a composition ratio of 54 mass%. Furthermore, intermediate C, which can be used as a raw material for the target product 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane in the subsequent step (Example 4), was also obtained. ４ Cl ７ F ３ (1,1,1,2,3,4,4-heptachloro-1,2,3-trifluorobutane), C ４ Cl ５ F ５ (1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane) was contained in composition ratios of 12 mass % and 7 mass %, respectively.

[0025] Example 4: Fluorination reaction with chlorine monofluoride (ClF) 200 g of the reaction solution of the fluorination reaction containing 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane obtained in Example 3 was added to an SUS reactor equipped with a gas inlet, a gas outlet, and a thermometer. An ice-cooled trap and a -20°C condenser were installed on the gas outlet side of the reactor. The reactor was heated to 120°C, and chlorine monofluoride was bubbled through at a flow rate of 2.4 L / hr for 16 hours. Nitrogen was then bubbled through at the same flow rate for 1 hour, yielding 161 g of a reaction solution. Analysis of this reaction solution revealed that it contained 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane in a composition ratio of 56 mass%.

[0026] Example 5: Chlorine trifluoride (ClF ３ Fluorination reaction with hexachlorobutadiene (C) ４ Cl ６345 g of 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane, which is produced by fluorine addition to the unsaturated bonds of hexachlorobutadiene, was contained in a composition ratio of 31 mass %. Furthermore, intermediate C, which can be used as a raw material for the target product 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane in the subsequent step (Example 4), was obtained. ４ Cl ７ F ３ (1,1,1,2,3,4,4-heptachloro-1,2,3-trifluorobutane), C ４ Cl ５ F ５ (1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane) was contained in composition ratios of 17% by mass and 3% by mass, respectively.

[0027] Comparing Example 3 and Example 5, F ２ The gas is ClF ３ It was found that the selectivity of 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane was higher than that of the gas. The products obtained in Examples 3 and 5 were both capable of being converted into the target product 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane (C ４ Cl ４ F ６ ) and this C ４ Cl ４ F ６ can be converted to hexafluorobutadiene (HFB) by a known dechlorination reaction (Example 6). According to the present invention, chlorinated butane or chlorinated butadiene can be efficiently produced from TCE, which is relatively easily available, and fluorinated butane or fluorinated butadiene can also be produced. Therefore, etching gases with low environmental impact, such as HFB, can be produced in large quantities at low cost through a series of integrated processes.

[0028] (Example 6: Dechlorination Reaction with Metal) A water-cooled condenser and a dropping funnel were connected to a 300 ml glass reactor, and a 500 ml SUS gas collection vessel with a valve was connected to the end of the cooling condenser. 70 g of isopropyl alcohol solvent and 41 g of granular zinc metal were added to the reactor, and the temperature of the reactor was raised to 70 ° C. while stirring, and the gas collection vessel was cooled in a dry ice-acetone bath. Next, a distillate containing 40 g of 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane obtained by distilling the reaction solution of Example 4 was added dropwise to the reaction solution using a dropping funnel over 1 hour, and then the reaction was allowed to proceed for 5 hours. After completion of the reaction, the product collected in the gas collection vessel was analyzed by gas chromatography, and the HFB purity was found to be 97 GC%. The yield based on 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane was 94 mol %.

Claims

1. The following formula (1): 【Chemistry 1】 Hexachlorobutadiene (C) is produced by chlorination and dehydrochlorination of a dimer of trichloroethylene (TCE) represented by the formula: ４ Cl ６ ), a method for producing In the presence of a Lewis acid catalyst, TCE dimer and chlorine gas (Cl ２ ) with

2. 10. The process of claim 1, wherein the reaction is carried out at a temperature of from 30 to 200°C.

3. The Lewis acid catalyst is FeCl ３ 3. The method of claim 1 or 2, comprising:

4. A method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane from trichloroethylene (TCE), comprising the steps of: (A) Trichloroethylene (TCE) is converted into the following formula (1): 【Chemistry 2】 wherein step (A) comprises dimerizing TCE using the dimer represented by formula (1) as a solvent in the presence of a free radical generator at a temperature of 100°C or higher; (B) Hexachlorobutadiene (C) is obtained by chlorination and dehydrochlorination of the dimer of TCE represented by the formula (1). ４ Cl ６ ), wherein step (B) is a step of preparing a fluorine-containing fluoride (F) by using FeCl as a reaction catalyst. ３ In the presence of TCE dimer and chlorine gas (Cl ２ ) with (C) Hexachlorobutadiene (C ４ Cl ６ fluorinating 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane with a fluorinating agent to produce a fluorinated product comprising 1,1,2,3,4,4-hexachloro-1,2,3,4-tetrafluorobutane; and (D) A step of reacting the fluorinated product obtained in step (C) with chlorine monofluoride (ClF) to produce 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane. The method comprising:

5. The fluorinated product obtained in the step (C) is further converted into 1,1,1,2,3,4,4-heptachloro-1,2,3-trifluorobutane (C ４ Cl ７ F ３ ) and 1,1,2,3,4-pentachloro-1,2,3,4,4-pentafluorobutane (C ４ Cl ５ F ５ 5. The method of claim 4, comprising:

6. From trichloroethylene (TCE), the following formula (1): 【Transformation 3】 The method for producing a dimer of TCE represented by formula (1) comprises a step of dimerizing TCE at a temperature of 100°C or higher in the presence of a free radical generator using the dimer represented by formula (1) as a solvent.

7. The process of claim 6, wherein the reaction is carried out at a temperature of from 100 to 200°C.

8. 8. The process according to claim 6 or 7, wherein the reaction is carried out at atmospheric pressure.

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