A quantitative detection method for a mixture of hexafluoropropylene oxide and hexafluoropropylene gas.

Abstract

This application discloses a quantitative detection method for a mixture of hexafluoropropylene oxide and hexafluoropropylene, characterized by the following steps: 1) establishing standard curves for methyl pentafluoropropionate and hexafluoropropylene using standards; 2) isomerizing the hexafluoropropylene oxide in the mixture to obtain methyl pentafluoropropionate; 3) detecting methyl pentafluoropropionate and hexafluoropropylene separately, substituting the results into the standard curves to obtain their contents; and then converting the content of methyl pentafluoropropionate into the content of hexafluoropropylene oxide. The method provided in this application features mild reaction conditions and simple operation, solving the problem of difficult separation of hexafluoropropylene oxide and hexafluoropropylene mixtures in the gas phase, and enabling rapid separation and quantitative detection of hexafluoropropylene oxide and hexafluoropropylene.

Description

Technical Field

[0001] This application relates to the field of chemical technology, and in particular to a quantitative detection method for a mixture of hexafluoropropylene oxide and hexafluoropropylene gas. Background Technology

[0002] Hexafluoropropylene oxide and hexafluoroacetone are the two most important fluorinated compounds among hexafluoro compounds. Their trifluoromethyl structure has high chemical activity and can be used as intermediates for many fluorinated organic compounds. They are widely used in aerospace, electronics, nuclear power engineering, medicine and other fields, and are one of the most important fluorinated intermediates in the production of organofluorine materials.

[0003] In existing hexafluoropropylene oxide synthesis processes, hexafluoropropylene is mainly used as a raw material. However, because the boiling points of these two substances are very close (hexafluoropropylene oxide -27℃, hexafluoropropylene -29.4℃), they are difficult to separate. Currently, analytical methods using stainless steel or tetrafluoroethylene columns in gas chromatography cannot achieve accurate quantitative detection results. Therefore, developing a gas chromatography method for the quantitative detection of a mixture of hexafluoropropylene oxide and hexafluoropropylene is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a quantitative detection method for a mixture of hexafluoropropylene oxide and hexafluoropropylene. The method provided in this application features mild reaction conditions and simple operation, solving the problem of difficult separation of the mixture of hexafluoropropylene oxide and hexafluoropropylene in the gas phase, and enabling rapid separation and quantitative detection of hexafluoropropylene oxide and hexafluoropropylene.

[0005] The technical solution provided by this invention is as follows:

[0006] A method for quantitative detection of a mixture of hexafluoropropylene oxide and hexafluoropropylene, comprising the following steps:

[0007] 1) Using standards, establish standard curves for methyl pentafluoropropionate and hexafluoropropylene respectively;

[0008] 2) Isomerize the hexafluoropropylene oxide in the mixed gas to obtain methyl pentafluoropropionate;

[0009] 3) Detect methyl pentafluoropropionate and hexafluoropropylene separately, and substitute them into the standard curve to obtain the content; then convert the content of methyl pentafluoropropionate into the content of hexafluoropropylene oxide.

[0010] Preferably, in step 2), the mixed gas is passed into a potassium fluoride methanol solution, and under heating conditions, hexafluoropropylene oxide isomerizes to obtain methyl pentafluoropropionate. Then, the methyl pentafluoropropionate solution and the unreacted hexafluoropropylene gas are collected separately.

[0011] Preferably, the concentration of the potassium fluoride methanol solution is 50-80 g / L, the mass ratio of hexafluoropropylene oxide to potassium fluoride is 10:1-20:1, the reaction temperature is 40-60℃, and the rate of introducing the mixed gas is 1-2 mL / min.

[0012] Preferably, in step 3), the conversion of methyl pentafluoropropionate to hexafluoropropylene oxide is calculated using the following formula:

[0013]

[0014] In the formula:

[0015] C represents the concentration of methyl pentafluoropropionate, in mg / L;

[0016] V is the volume of the potassium fluoride methanol solution, in L;

[0017] M is the relative molecular mass of methyl pentafluoropropionate;

[0018] n is the amount of substance of hexafluoropropylene oxide, in mol.

[0019] Preferably, gas chromatography is used to establish a standard curve and to detect methyl pentafluoropropionate and hexafluoropropylene.

[0020] The detection conditions for methyl pentafluoropropionate are as follows:

[0021]

[0022] The testing conditions for hexafluoropropylene are as follows:

[0023]

[0024]

[0025] Preferably, in step 1), the step of establishing the standard curve of methyl pentafluoropropionate specifically involves: preparing a series of standard samples of methyl pentafluoropropionate at different concentrations, performing gas chromatography detection, and using the external standard method to obtain the standard curve of peak area versus methyl pentafluoropropionate concentration.

[0026] The specific steps for establishing the standard curve of hexafluoropropylene are as follows: dilute with nitrogen to prepare a series of hexafluoropropylene standard samples with different volume fractions, perform gas phase detection, and use the external standard method to obtain the standard curve of peak area versus hexafluoropropylene volume fraction.

[0027] Preferably, the standard samples of methyl pentafluoropropionate are prepared with a series of concentrations, the concentration range of methyl pentafluoropropionate being between 5000-25000 mg / L.

[0028] In the mixed gas, hexafluoropropylene accounts for 5-60% of the volume percentage of the mixed gas.

[0029] Preferably, the purity of the nitrogen gas used is greater than 99.99%.

[0030] Preferably, the purity of the standards for hexafluoropropylene oxide, hexafluoropropylene, and methyl pentafluoropropionate used is greater than 99%.

[0031] This application provides a method for the quantitative detection of a mixture of hexafluoropropylene oxide and hexafluoropropylene. The method involves isomerizing hexafluoropropylene oxide to methyl pentafluoropropionate, while hexafluoropropylene remains in its original form without participating in the reaction. This separates the methyl pentafluoropropionate and hexafluoropropylene, allowing for separate content measurement of each. The content of methyl pentafluoropropionate is then converted into the content of hexafluoropropylene oxide, thus obtaining the individual contents of hexafluoropropylene oxide and hexafluoropropylene in the gas mixture. This method solves the problem of difficulty in separating and quantifying hexafluoropropylene oxide and hexafluoropropylene mixtures in the gas phase. The method provided in this application features mild reaction conditions, is simple to operate, and enables rapid separation and quantitative detection of hexafluoropropylene oxide and hexafluoropropylene.

[0032] Preferably, the isomerization of hexafluoropropylene oxide to methyl pentafluoropropionate is achieved by passing a mixed gas into a potassium fluoride methanol solution and reacting hexafluoropropylene oxide, potassium fluoride, and methanol under heating conditions. The reaction process is as follows:

[0033]

[0034] When the mixed gas is introduced, the concentration of potassium fluoride methanol solution is 50-80 g / L, the mass ratio of hexafluoropropylene oxide to potassium fluoride is 10:1-20:1, the reaction temperature is 40-60℃, and the rate of introducing the mixed gas is 1-2 mL / min, so that the hexafluoropropylene oxide reacts completely.

[0035] Both the establishment of the optimal standard curve and the actual detection were performed using gas chromatography. The gas chromatography conditions are as follows:

[0036] The detection conditions for methyl pentafluoropropionate are as follows:

[0037]

[0038] The testing conditions for hexafluoropropylene are as follows:

[0039]

[0040] For gas chromatography, you can choose the Shimadzu GC2014C gas chromatograph, or other gas chromatographs commonly used in this field. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a gas chromatogram of the methyl pentafluoropropionate standard sample in an embodiment of the present invention;

[0043] Figure 2 This is a gas chromatogram of the hexafluoropropylene standard sample in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the standard relationship curve between the peak area and concentration of methyl pentafluoropropionate in an embodiment of the present invention.

[0045] Figure 4 This is a schematic diagram illustrating the standard relationship between the peak area and volume fraction of hexafluoropropylene in an embodiment of the present invention. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] The gas chromatograph used in this embodiment is a Shimadzu GC2014C gas chromatograph.

[0048] The purity of the standards for hexafluoropropylene oxide, hexafluoropropylene, and methyl pentafluoropropionate used is greater than 99%.

[0049] The nitrogen gas used has a purity greater than 99.99%.

[0050] Example 1

[0051] A method for quantitative detection of a mixture of hexafluoropropylene oxide and hexafluoropropylene, comprising the following steps:

[0052] 1) Using standard substances, prepare a series of standard samples of methyl pentafluoropropionate at various concentrations, perform gas chromatography detection, and obtain a standard curve of peak area versus methyl pentafluoropropionate concentration using the external standard method; dilute with nitrogen to prepare a series of standard samples of hexafluoropropylene at various volume fractions, perform gas chromatography detection, and obtain a standard curve of peak area versus hexafluoropropylene volume fraction using the external standard method; wherein the concentration range of methyl pentafluoropropionate in the prepared standard samples of various concentrations is between 5000-25000 mg / L.

[0053] 2) The mixed gas is passed into a potassium fluoride methanol solution with a concentration of 60 g / L, the mass ratio of hexafluoropropylene oxide to potassium fluoride is 10:1, the reaction temperature is 40℃, and the rate of passing the mixed gas is 1 mL / min.

[0054] 3) Methyl pentafluoropropionate and hexafluoropropylene were tested separately. The injection volume of methyl pentafluoropropionate solution was 0.2 μL, and the injection volume of hexafluoropropylene was 1.0 mL. The contents were substituted into the standard curve to obtain the contents. Then the contents of methyl pentafluoropropionate were converted into the contents of hexafluoropropylene oxide.

[0055] The gas chromatography conditions are as follows:

[0056] The detection conditions for methyl pentafluoropropionate are as follows:

[0057]

[0058] The testing conditions for hexafluoropropylene are as follows:

[0059]

[0060] The conversion of methyl pentafluoropropionate to hexafluoropropylene oxide is calculated using the following formula:

[0061]

[0062] In the formula:

[0063] C represents the concentration of methyl pentafluoropropionate, in mg / L; in this example, C is 9.62 × 10⁻⁶. 3 mg / L; V is the volume of potassium fluoride methanol solution, L; in this example, V is 0.05M; M is the relative molecular mass of methyl pentafluoropropionate; in this example, M is 178.06 g / mol; n is the amount of substance of hexafluoropropylene oxide, mol.

[0064] The test results are shown in Table 1:

[0065] Table 1

[0066]

[0067] Example 2

[0068] Another mixed gas with a different concentration was tested, using the same reagent parameters and testing procedures as in Example 1. The results are shown in Table 2:

[0069] Table 2

[0070]

[0071] Example 3

[0072] The known concentrations of the mixed gas were tested and verified. A mixture of hexafluoropropylene (30% by volume, 0.0013 mol molar) and hexafluoropropylene (30% by volume, 0.0013 mol molar) was prepared. Except for the addition of 0.03 L of potassium fluoride methanol solution, the testing procedures were the same as in Example 1. The purity of the hexafluoropropylene standard used in Example 3 was greater than 99%.

[0073] The results are shown in Table 3:

[0074] Table 3

[0075]

[0076] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for quantitative detection of a mixture of hexafluoropropylene oxide and hexafluoropropylene, characterized in that, Includes the following steps: 1) Using standard products, establish standard curves for methyl pentafluoropropionate and hexafluoropropylene respectively; 2) Isomerize the hexafluoropropylene oxide in the mixed gas to obtain methyl pentafluoropropionate; 3) Detect methyl pentafluoropropionate and hexafluoropropylene separately, and substitute them into the standard curve to obtain the content; then convert the content of methyl pentafluoropropionate into the content of hexafluoropropylene oxide. In step 2), the mixed gas is passed into a potassium fluoride methanol solution and is heated to isomerize hexafluoropropylene oxide to obtain methyl pentafluoropropionate. Then, the methyl pentafluoropropionate solution and the unreacted hexafluoropropylene gas are collected separately. A standard curve was established and methyl pentafluoropropionate and hexafluoropropylene were detected using gas chromatography. The detection conditions for methyl pentafluoropropionate are as follows: The testing conditions for hexafluoropropylene are as follows: 。 2. The quantitative detection method according to claim 1, characterized in that, The concentration of potassium fluoride in methanol solution is 50-80 g / L, the mass ratio of hexafluoropropylene oxide to potassium fluoride is 10:1-20:1, the reaction temperature is 40-60℃, and the rate of introducing the mixed gas is 1-2 mL / min.

3. The quantitative detection method according to claim 1, characterized in that, In step 3), the conversion of methyl pentafluoropropionate to hexafluoropropylene oxide is calculated using the following formula: In the formula: C represents the concentration of methyl pentafluoropropionate, in mg / L; V is the volume of the potassium fluoride methanol solution, in L; M is the relative molecular mass of methyl pentafluoropropionate; n is the amount of substance of hexafluoropropylene oxide, in mol.

4. The quantitative detection method according to claim 1, characterized in that, In step 1), the specific steps for establishing the standard curve of methyl pentafluoropropionate are as follows: prepare a series of standard samples of methyl pentafluoropropionate at different concentrations, perform gas chromatography detection, and use the external standard method to obtain the standard curve of peak area versus methyl pentafluoropropionate concentration. The specific steps for establishing the standard curve of hexafluoropropylene are as follows: dilute with nitrogen to prepare a series of hexafluoropropylene standard samples with different volume fractions, perform gas phase detection, and use the external standard method to obtain the standard curve of peak area versus hexafluoropropylene volume fraction.

5. The quantitative detection method according to claim 4, characterized in that, A series of standard samples of methyl pentafluoropropionate were prepared, with the concentration range of methyl pentafluoropropionate between 5000-25000 mg / L. In the mixed gas, hexafluoropropylene accounts for 5-60% of the total volume.

6. The quantitative detection method according to any one of claims 1 or 4, characterized in that, The nitrogen gas used has a purity greater than 99.99%.

7. The quantitative detection method according to claim 1, characterized in that, The purity of the hexafluoropropylene and methyl pentafluoropropionate standards used is greater than 99%.

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