Method for producing trifluoroacetyl fluoride and carbonyl fluoride

Abstract

The present invention provides a method for simply, safely and industrially producing trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF2).　This method for producing trifluoroacetyl fluoride and carbonyl fluoride includes a step for introducing at least one reactant selected from the group consisting of hexafluoropropylene and hexafluoropropylene oxide, and oxygen and a diluent compound into a reactor to obtain a product gas containing trifluoroacetyl fluoride and carbonyl fluoride.

Description

Method for producing trifluoroacetyl fluoride and carbonyl fluoride

[0001] The present invention relates to a method for producing trifluoroacetyl fluoride and carbonyl fluoride.

[0002] A known method for synthesizing trifluoroacetyl fluoride (TFAF) is to photo-oxidize tetrachloroethylene to obtain trichloroacetyl chloride, and then fluorinate the resulting trichloroacetyl chloride (Patent Document 1). (In the above formula, "O ２ , hv" means "photo-oxidation" and "Cr cat." means "chromium catalyst.")

[0003] Also known is a method of reacting trifluoroacetyl chloride with an ammonium hydrogen fluoride salt or a hydrogen fluoride adduct of a hydrofluoride salt of an organic nitrogen base (Patent Document 2). (In the above formula, "Bu" means a "butyl group.")

[0004] In addition, as a reaction example similar to the direct oxidation method, which is an industrial production method of ethylene oxide, a method of synthesizing ethylene oxide from hexafluoropropylene (HFP) and molecular oxygen via the intermediate hexafluoropropylene oxide (HFPO) is known (Patent Document 3, Non-Patent Document 1). (In the above formula, "Δ" means "heating.")

[0005] KR10-0468526B1KR2001-0081024AKR10-2015-0010938A

[0006] Chem. Eng. Comm. ,2014,201,1173-1197

[0007] However, the method of Patent Document 1 has problems in terms of equipment, such as the need for a photoreaction device, and problems in that a metal catalyst is required for the separation and purification steps of the intermediate and the fluorination reaction. Furthermore, the method of Patent Document 2 has problems in that the work process is complicated, such as the need to prepare a specific hydrogen fluoride adduct, and problems in that HCl is by-produced in the reaction system, and HCl forms a complex with the product TFAF, resulting in a decrease in the yield of free TFAF. The methods of Patent Document 3 and Non-Patent Document 1 are primarily intended to selectively synthesize HFPO, and do not involve the synthesis of TFAF and COF. ２ The yield of TFAF and COF was low. ２ The reaction conditions for the industrial production of ethylene have not yet been established. In addition, in the direct oxidation of ethylene, the high reactivity of epoxides makes it difficult to obtain N ２ , Ar, CO ２ However, the examples in Patent Document 3 and Non-Patent Document 1 involve reactions using only raw material gases, which poses a risk of runaway reaction during industrial-scale production. Furthermore, a reactor made of coiled copper piping over 100 m in length is used, while the maximum total flow rate is 1 L / min or less, and no industrial-scale synthesis examples have been reported. Therefore, the object of the present invention is to provide a method for producing a fluorine-containing compound by diluting trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF ２ The present invention aims to provide a method for producing hydroxybenzoates (hydroxybenzoates) in a simple, safe and industrial manner.

[0008] As a result of extensive research to solve the above problems, the present inventors have found that trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF ２The present inventors have discovered a simple, safe, and industrially viable method for producing trifluoroacetyl fluoride and carbonyl fluoride, and have completed the present invention. Specifically, the present invention provides the following: [1] A method for producing trifluoroacetyl fluoride and carbonyl fluoride, comprising the step of introducing at least one reactant selected from the group consisting of hexafluoropropylene and hexafluoropropylene oxide, oxygen, and a diluent compound in the gas phase into a reactor at 240 to 650°C to obtain a product gas containing trifluoroacetyl fluoride and carbonyl fluoride. [2] The method according to [1], wherein the diluent compound is at least one selected from the group consisting of nitrogen, a rare gas, trifluoroacetyl fluoride, carbonyl fluoride, and the product gas supplied to the reactor. [3] The method according to any one of [1] to [2], wherein a member made of a metal containing Ni is attached to the reactor so as to occupy no more than 20% by volume of the free space within the reactor. [4] The method according to any one of [1] to [2], wherein a reactor is used in which the Ni content of the metal constituting the gas contact surface inside the reactor is 30% by weight or more. [5] The method according to any one of [1] to [2], wherein the oxygen is introduced into the reactor in a range of 0.1 to 50.0 molar equivalents relative to the reactants. [6] The method according to any one of [1] to [2], wherein the diluent compound accounts for 1 to 50% of the total volume of the reactants, the oxygen, and the diluent compound.

[0009] According to the present invention, trifluoroacetyl fluoride and carbonyl fluoride (COF ２ The method of the present invention does not require the use of a photoreactor or a specific hydrogen fluoride adduct, and does not involve the problem of complicated working steps.

[0010] Fig. 1 is a diagram showing an outline of an apparatus for carrying out the method of the present invention. Fig. 2 is a diagram showing an embodiment of the invention in which a metal member is arranged inside a reactor. Fig. 3 is a diagram showing structural examples (a) and (b) of a metal member to be arranged inside a reactor. Fig. 4 is a diagram showing four metal members (baffles) arranged inside a reactor used in the examples and their arrangement.

[0011] (Action) The present invention is a method for producing trifluoroacetyl fluoride and carbonyl fluoride, characterized by comprising a step of introducing at least one reactant selected from the group consisting of hexafluoropropylene and hexafluoropropylene oxide, oxygen, and a diluent compound in the gas phase into a reactor at 240 to 650°C to obtain a product gas containing trifluoroacetyl fluoride and carbonyl fluoride. In the present invention, by introducing a diluent compound that is not directly involved in the reaction in a gaseous state into the reactor in addition to the reactants and oxygen, a rapid exothermic reaction between the reactants and oxygen is suppressed, thereby suppressing decomposition of the product and the generation of by-products due to side reactions, and allowing the target products, trifluoroacetyl fluoride and carbonyl fluoride, to be obtained in good yield.

[0012] Furthermore, the inventors have found through their investigations that the target products, trifluoroacetyl fluoride and carbonyl fluoride, can be obtained in good yield by forming the inner surface of the reactor from nickel or a nickel alloy, or by attaching a member made of a metal containing Ni to the inside of the reactor.

[0013] (Reactant) The reactant (reaction substrate) in the method of the present invention is at least one selected from the group consisting of hexafluoropropylene (HFP) and hexafluoropropylene oxide (HFPO). In the reaction of the present invention, HFPO is produced by an oxidation reaction of HFP, and the oxidation reaction further progresses, resulting in decomposition of the C-C bond constituting the oxirane ring, to produce trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF ２ Therefore, whether starting from HFP or HFPO as the reactants, the target TFAF and COF are obtained. ２ The products TFAF and COF ２ Since is hydrolyzable, it is preferable that the reactants, diluent compounds, and the inside of the reactor contain as little water as possible.

[0014] (Dilution Compound) Examples of the dilution compound include nitrogen, rare gases (helium, neon, argon, krypton, xenon, radon, etc.), trifluoroacetyl fluoride, carbonyl fluoride, and the product gas supplied to the reactor. These may be used in combination of two or more, and air containing nitrogen or argon may also be used. The product gas may be supplied by re-supplying the reactor outlet gas to the reactor inlet, or by re-supplying gas that has been collected once. The dilution compound preferably accounts for 1 to 50% by volume, and more preferably 25 to 50% by volume, of the gas introduced into the reactor.

[0015] (Reaction Conditions) The reaction of the present invention is carried out by heating oxygen and at least one reactant selected from the group consisting of hexafluoropropylene (HFP) and hexafluoropropylene oxide (HFPO) in the presence of a diluent compound. The reaction is typically carried out at a temperature of 240 to 650°C, preferably 300 to 600°C, and more preferably 350 to 550°C. The amount of oxygen used relative to the reactant is preferably 0.1 to 50.0 molar equivalents, more preferably 0.1 to 10.0 molar equivalents, and even more preferably 0.5 to 3.0 molar equivalents. When HFP alone is used as a reactant, twice the molar equivalent of oxygen is required compared to when HFPO alone is used as a reactant. Therefore, the amount of oxygen is adjusted within the above range depending on the volume ratio (molar ratio) of HFP to HFPO contained in the reactants.

[0016] (Reactor) In the present invention, it is preferable to use a reactor in which the metal constituting the gas contact surface has a nickel (Ni) content of 30% by weight or more. To this end, it is preferable that at least the gas contact surface of the reactor be made of nickel or a nickel-containing alloy. Only the contact surface may be coated with these metals, or a portion or all of the components may be made of these metals. In the nickel-containing alloy, the proportion of nickel is preferably 30% by weight or more, more preferably 56% by weight or more, and even more preferably 69% by weight or more, based on the weight of the entire alloy. Examples of nickel-containing alloys include Hastelloy (registered trademark) B-2, Hastelloy B-3, Hastelloy C-4, Hastelloy C-2000, Hastelloy C-22, Hastelloy C-276, Hastelloy N, Hastelloy W, Monel (registered trademark) 400, Monel K500, Inconel (registered trademark) 600, Inconel 625, and Inconel X750. Nickel or nickel-containing alloys have excellent corrosion resistance and are suitable for long-term mass production. For example, as will be described later, SUS has poor corrosion resistance and tends to generate corrosion powder, which poses a risk of clogging pipes.

[0017] Furthermore, a member made of a metal containing Ni may be installed in the reactor so as to occupy no more than 20% of the volume of the space in the reactor. The member may be in the shape of a plate such as a baffle, and a plurality of members may be installed side by side. By installing such a member, the introduced gases can be mixed and the reaction efficiency can be improved. When a member such as a baffle is installed in the reactor, the target product can be synthesized with a yield equal to or higher than that when a baffle is not installed, even with a smaller amount of oxygen.

[0018] FIG. 1 is a diagram showing an outline of an apparatus for carrying out the method of the present invention. In FIG. 1, a cylinder 1 containing a reaction substrate (HFP or HFPO) and oxygen (O ２A cylinder 2 containing oxygen and a diluent compound is provided, and pipes 4, 5, and 6 extend from cylinders 1, 2, and 3, respectively, toward the reactor. Pipes 4, 5, and 6 join at pipe 7 and are connected to a cylindrical reactor 9, which is circumferentially equipped with a heater 8 for temperature control. The reaction substrate, oxygen, and diluent compound gases discharged from cylinders 1, 2, and 3 pass through pipes 4, 5, and 6, respectively, join at pipe 7, and are introduced into the reactor, which is heated to the reaction temperature by heater 8, where a reaction occurs to produce the products trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF ２ ) is produced. The product gas after the reaction is recovered through pipe 10. When the product gas is used as a diluent compound or when unreacted reactants contained in the product gas are reused, the product gas can be sucked through pipe 11 by pump 12 and returned through pipe 13 to pipe 7 immediately before the inlet of reactor 9. A portion of the product gas sucked through pump 12 can be returned to pipe 10 through pipe 14 to adjust the pressure in the pipe.

[0019] FIG. 2 is a diagram showing an embodiment of the invention in which a metal member 15 is disposed inside a reactor. The member 15 serves to control the flow of reactants. Therefore, the member 15 may be disposed parallel to the flow of reactants or so as to interrupt the flow of reactants. In FIG. 2, four disk-shaped members are disposed inside the reactor so as to interrupt the flow of reactants. FIG. 3 is a diagram showing structural examples (a) and (b) of a metal member disposed inside the reactor. When the member 15 is disposed so as to interrupt the flow of reactants, as shown in FIG. 3, multiple holes are formed in the member 15 so that the reactant flow passes through the reactor. The structural example (a) is an example in which five holes are formed in a cross shape on a disk, and the structural example (b) is an example in which four holes are formed at equal intervals around the circumference. FIG. 4 is a diagram showing the arrangement of four metal members (baffles) disposed inside a reactor used in the examples described below. In Fig. 4, four members of the structural examples (a) and (b) of Fig. 3 are alternately arranged so that the holes arranged along the circumference are offset at an angle of 30° from the axis of the flow path direction, and are installed at positions of 1 / 10, 1 / 4, 1 / 2, and 3 / 4 of the entire length of the reactor from the reactor inlet. In this way, in the method of the present invention, the reaction can be controlled by adjusting the number, shape, and arrangement of the members 15.

[0020] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. (Example 1) Hexafluoropropylene (C ３ F ６ ), oxygen (O ２ ), the diluted compound was introduced, and trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF) were detected by gas chromatography (GC-TCD). ２ The formation of 2,4-dichloro-2,4-trimethylsilyl ...

[0021]

[0022]

[0023] As can be seen from Table 1, in various reactor sizes ranging from 1 inch in diameter to 6 inches in diameter, there was no pressure fluctuation during the test due to abnormal heat generation, and TFAF and COF were obtained over a wide range of the diluent compound ratio (the ratio of the flow rate of the diluent compound to the total flow rate of hexafluoropropylene, oxygen, and the diluent compound) from 25.0 to 50.0%. ２ Good yield (TFAF: 75% or more, COF ２ Regarding the yield, TFAF was found to be obtained by thermal decomposition with COF ２ Therefore, under conditions where the amount of dilution compound is small and local reactions tend to proceed, the thermal decomposition reaction tends to proceed, resulting in a decrease in the yield of TFAF and COF ２ The yield of TFAF and COF tends to increase. ２ If equimolar amounts of TFAF and COF are produced, the reaction is well controlled, and the closer the yield is to 100%, the more appropriate the reaction conditions (temperature, pressure, the composition of reactants, oxygen and diluent compounds, the structure inside the reactor, etc.) are. According to the studies of the present inventors, the range of good yields is 75% or more for TFAF, 75% or more for COF, and 75% or more for COF. ２ The yield was 60% or more for the above-mentioned test results, and good yields were achieved in all of them.

[0024] Example 2 Hexafluoropropylene oxide (HFPO), oxygen (O ２ ), the diluted compound was introduced, and trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF) were detected by gas chromatography (GC-TCD). ２ The experimental conditions and results are shown in Tables 3 and 4.

[0025]

[0026]

[0027] From Table 3, when the reactant was HFPO, even with a small oxygen flow rate, TFAF and COF ２It was found that when HFPO was used as the reactant, TFAF and COF were obtained in a better yield than when HFP was used as the reactant. ２ It was found that there was an advantageous effect that the amount of by-product impurities was surprisingly small.

[0028] Example 3 Hexafluoropropylene (C) was introduced into a heated Ni reactor containing Ni components (Ni baffles: two discs of each of the structural example (a) and the structural example (b) of FIG. 3, a total of four discs) that accounted for 1.2% by volume of the volume of the reactor space. ３ F ６ ), oxygen (O ２ ), the diluted compound was introduced, and trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF) were detected by gas chromatography (GC-TCD). ２ The generation of Ni was confirmed. The Ni baffle plates were arranged as shown in Figure 4, with four plates of the structural examples (a) and (b) of Figure 3 alternately arranged so that the holes arranged along the circumference were offset by an angle of 30° from the flow direction as an axis, and were installed at positions of 1 / 10, 1 / 4, 1 / 2, and 3 / 4 of the entire length of the reactor from the reactor inlet. In a reactor with a length of 1 m, the discs of structural example (a), structural example (b), structural example (a), and structural example (b) (each disc had a thickness of 3 mm) were arranged at positions 10 cm, 25 cm, 50 cm, and 75 cm from the inlet side (left side of Figure 4), respectively. Tables 5 and 6 show the experimental conditions and results. When product gas was used as the diluent compound, a portion of the product gas was recirculated as is so that the composition of the diluent compound was the same as that of the product gas.

[0029]

[0030]

[0031] From Table 5, it can be seen that even when Ni baffles were installed in a large reactor having a diameter of 6 inches and reactants, oxygen, and diluent compounds were flowed at high flow rates, a good yield could be achieved.

[0032] (Example 4) Hexafluoropropylene (C ３ F ６ ), oxygen (O ２), the diluted compound was introduced, and trifluoroacetyl fluoride (TFAF) and carbonyl fluoride (COF) were detected by gas chromatography (GC-TCD). ２ The experimental conditions and results are shown in Tables 7 and 8.

[0033]

[0034]

[0035] Although the target product was obtained in good yield, corrosion of the SUS reactor was observed after the test with R-9.

Claims

1. A method for producing trifluoroacetyl fluoride and carbonyl fluoride, comprising the steps of: introducing at least one reactant selected from the group consisting of hexafluoropropylene and hexafluoropropylene oxide, oxygen and a diluent compound in the gas phase into a reactor at 240-650°C to obtain a product gas containing trifluoroacetyl fluoride and carbonyl fluoride.

2. The method of claim 1, wherein said diluent compound is at least one selected from the group consisting of nitrogen, a noble gas, trifluoroacetyl fluoride, carbonyl fluoride, and said product gas fed to the reactor.

3. The method according to any one of claims 1 to 2, wherein a member made of a metal containing Ni is attached inside the reactor so as to occupy a range not exceeding 20 volume % of the space volume inside the reactor.

4. The method according to any one of claims 1 to 2, wherein a reactor is used in which the Ni content of the metal constituting the gas contact surface inside the reactor is 30% by weight or more.

5. The method according to any one of claims 1 to 2, wherein the oxygen is introduced into the reactor in the range of 0.1 to 50.0 molar equivalents relative to the reactants.

6. The method of any one of claims 1 to 2, wherein the diluent compound comprises 1 to 50% of the combined volume of the reactants, the oxygen and the diluent compound.

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