Preparation method of 2, 3, 3, 3-tetrafluoropropene

Abstract

The invention relates to the technical field of compound preparation, in particular to a preparation method of 2, 3, 3, 3-tetrafluoropropene, which comprises the following steps: carrying out Markov addition synthesis reaction on 3, 3, 3-trifluoro-1-propyne and a fluorinating reagent to obtain 2, 3, 3, 3-tetrafluoropropene; the fluorination reagent is prepared from pyridinium tetrafluoroborate; the structural formula of the pyridinium tetrafluoroborate is shown as a formula I, R1, R2, R3, R4 and R5 are independently selected from hydrogen and halogens, and at least two of R1, R2, R3, R4 and R5 are selected from halogens. The invention develops a new route for preparing 2, 3, 3, 3-tetrafluoropropene, and the preparation method has the advantages of mild reaction conditions, low product separation difficulty and high production safety, and can optimize the conversion rate of the reaction raw material 3, 3, 3-trifluoro-1-propyne and the selectivity of the product 2, 3, 3, 3-tetrafluoropropene at the same time.

Description

Technical Field

[0001] This application relates to the field of compound preparation technology, specifically to a method for preparing 2,3,3,3-tetrafluoropropylene. Background Technology

[0002] 2,3,3,3-Tetrafluoropropene (R1234yf) is an important chemical product. Currently, there are two main methods for synthesizing R1234yf: Method 1: starting from 2-chloro-3,3,3-trifluoropropene (R1233xf), R1234xf is synthesized in one or two steps; Method 2: starting from (Z)-1,2,3,3,3-pentafluoropropene (R1225ye), R1234xf is synthesized in two steps.

[0003] The reaction pathway of Method 1 is as follows, but it has the following problems: it involves intermediates R1233xf and R244bb, which have similar boiling points and azeotropic properties. Both of these substances are also prone to forming azeotropes with HF, making the separation process extremely complex and difficult. Finally, when R244bb is dehydrochlorinated to prepare R1234yf, the R1233xf and HF impurities it contains can seriously affect the lifetime of the dehydrochlorination catalyst and the product selectivity.

[0004] .

[0005] The reaction path of Method 2 is as follows. Its problems are: the raw material cost is high, a stoichiometric amount of hydrogen needs to be introduced, and a higher molar ratio is required in the hydrogenation step to control the heat of reaction. Introducing excessive hydrogen at a higher temperature will increase the relevant safety risks.

[0006] .

[0007] In addition to the aforementioned mainstream methods, CN 117342922 A reports a method with the following reaction pathway: 1,2-dichloro-3,3,3-trifluoropropene undergoes a dechlorination reaction with a metal to prepare trifluoropropyne; then, under the action of a liquid-phase fluorination catalyst, trifluoropropyne undergoes an addition reaction with HF to prepare 2,3,3,3-tetrafluoropropene. This method involves the use of the corrosive gas HF, which is relatively dangerous, and also has low product selectivity, as it is accompanied by the formation of 1,3,3,3-tetrafluoropropene.

[0008] .

[0009] In summary, current methods for preparing R1234yf have shortcomings such as expensive raw materials, environmentally unfriendly catalysts, difficulty in separating reaction intermediates, and low selectivity of the target product. Therefore, continuous improvement is needed to obtain more effective preparation methods. Summary of the Invention

[0010] In view of the above problems, this application provides a method for preparing 2,3,3,3-tetrafluoropropylene. This application develops a new route for preparing 2,3,3,3-tetrafluoropropylene. The preparation method has mild reaction conditions, low product separation difficulty, and high production safety. It can simultaneously optimize the conversion rate of the reactant 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropylene.

[0011] This application provides a method for preparing 2,3,3,3-tetrafluoropropylene, the method comprising the following steps: 3,3,3-trifluoro-1-propyne and a fluorinating agent were subjected to a Markovnikov addition reaction to synthesize 2,3,3,3-tetrafluoropropene; The fluorinating agent includes pyridinium tetrafluoroborate; The structural formula of the pyridinium tetrafluoroborate is shown in Formula I: Formula I; R1, R2, R3, R4 and R5 are each independently selected from hydrogen and halogens, and at least two of them are selected from halogens.

[0012] In the technical solution of this application, 3,3,3-trifluoro-1-propyne is used as the starting material for the reaction, which avoids the existing process route that uses R244bb or R245eb as the starting material or intermediate and uses strong bases such as sodium hydroxide in the reaction. As a result, the conversion rate of the reaction material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene are both kept at a high level.

[0013] Meanwhile, using the above-mentioned pyridinium tetrafluoroborate as a fluorinating agent to carry out a Markovnikov addition synthesis reaction with 3,3,3-trifluoro-1-propyne can avoid the use of chromium-based catalysts that are harmful to human health and environmentally unfriendly. Furthermore, the raw material cost is low, the method is simple, the production safety is high, and it can also meet the requirements of high conversion rate of the reactant 3,3,3-trifluoro-1-propyne and high selectivity of the product 2,3,3,3-tetrafluoropropene.

[0014] Preferably, R1 and R5 are each independently selected from halogens.

[0015] As an example, the halogen can be selected from fluorine, chlorine or bromine. This application does not limit the specific selection of halogens at different positions; they can be the same halogen or different halogens.

[0016] Preferably, R2 and R4 are selected from hydrogen.

[0017] Preferably, R3 is selected from H or halogens.

[0018] Preferably, the pyridinium tetrafluoroborate comprises at least one of the following compounds: , , , .

[0019] In the technical solution of this application, the above-mentioned pyridinium tetrafluoroborate is used, which helps to maintain the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene at a high level.

[0020] Preferably, the molar ratio of 3,3,3-trifluoro-1-propyne to the fluorinating agent is 1:(1~3), wherein 1~3 can be 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, or any combination of the above.

[0021] Preferably, the Markovnikov addition synthesis reaction is carried out in a solvent.

[0022] Preferably, the solvent includes at least one of toluene, chlorobenzene, trichlorotoluene, chloroform, 1,2-dichloroethane, or acetonitrile, more preferably at least one of chlorobenzene, trichlorotoluene, or chloroform, and even more preferably chloroform.

[0023] In the technical solution of this application, the above-mentioned solvent is used, which is beneficial to maintain the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene at a high level, especially the selectivity of the product 2,3,3,3-tetrafluoropropene is relatively excellent.

[0024] Preferably, 0.05 mol to 0.5 mol (e.g., 0.05 mol, 0.1 mol, 0.15 mol, 0.2 mol, 0.25 mol, 0.3 mol, 0.35 mol, 0.4 mol, 0.45 mol, 0.5 mol, or any combination thereof) of the 3,3,3-trifluoro-1-propyne is added per 100 mL of the solvent.

[0025] Preferably, the Marvibate addition synthesis reaction is carried out in a nitrogen atmosphere and / or an inert atmosphere.

[0026] In some embodiments, the inert atmosphere includes at least one gas atmosphere selected from helium, neon, argon, krypton, and xenon.

[0027] Preferably, the raw materials for the Markovnikov addition synthesis reaction also include additives.

[0028] Preferably, the additive includes tetrafluoroborate.

[0029] In the technical solution of the embodiments of this application, the above-mentioned additives can optimize the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene, especially significantly improving the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne.

[0030] Preferably, the additive includes sodium tetrafluoroborate (NaBF4), lithium tetrafluoroborate (LiBF4), tetraethylammonium tetrafluoroborate (N(Et)4BF4), or tetrabutylammonium tetrafluoroborate (N(Et)4BF4). n At least one of (-Bu)4BF4), more preferably lithium tetrafluoroborate.

[0031] Preferably, the molar ratio of the 3,3,3-trifluoro-1-propyne to the additive is 1:(0.1-2), wherein 0.1-1 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, or any combination of the above.

[0032] Preferably, the temperature of the Marvin addition synthesis reaction is 25℃-100℃, more preferably 50℃-80℃, and even more preferably 60℃-80℃, such as 25℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, or any combination of the above.

[0033] In the technical solution of this application, the temperature of the Marvin addition synthesis reaction is within the above-mentioned range, which can improve the conversion rate of the reactant 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene under mild conditions.

[0034] Preferably, the time for the Markovnikov addition synthesis reaction is 4-12 h, for example, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, or any combination of the above.

[0035] Preferably, the Markovnikov addition synthesis reaction further includes post-treatment, which includes cooling and elution after the reaction to obtain a filtrate and remove the solvent.

[0036] In the technical solution of this application, the post-processing method is simple and has the advantages of simple separation process, low separation difficulty and low azeotropic material formation.

[0037] As a preferred technical solution, the preparation method includes the following steps: (1) In a nitrogen atmosphere and / or an inert atmosphere, 3,3,3-trifluoro-1-propyne, pyridinium tetrafluoroborate, additives and solvent are mixed and a Marvin addition synthesis reaction is carried out, wherein the temperature of the Marvin addition synthesis reaction is 25-100℃ and the time is 4-10 h; (2) After the Markovnikov addition synthesis reaction is completed, the resulting mixture is cooled and eluted to obtain a filtrate. The solvent is then removed to obtain 2,3,3,3-tetrafluoropropylene.

[0038] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application.

[0039] Beneficial effects Compared with the prior art, the technical solution provided in this application has at least one of the following beneficial technical effects: (1) The preparation method provided in this application uses 3,3,3-trifluoro-1-propyne as the starting material for the reaction, which can avoid the use of R244bb and R245eb as the starting material or intermediate, strong bases such as sodium hydroxide, reduce by-products, reduce the requirements for separation process, and develop a new route for the preparation of 2,3,3,3-tetrafluoropropene.

[0040] (2) The preparation method provided in this application uses a specific pyridinium tetrafluoroborate as a fluorinating agent, which can avoid chromium-based catalysts that are harmful to the human body and unfriendly to the environment, while optimizing the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene.

[0041] (3) The preparation method provided in this application is novel, the reaction conditions are mild, and the production safety is high, which is a significant improvement.

[0042] Terminology Explanation Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0043] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is also expected that ranges of 60–110 and 80–120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "2-10" indicates that all real numbers between "2-10" have been listed in this article; "2-10" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship. Detailed Implementation

[0047] The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0048] I. Preparation method of 2,3,3,3-tetrafluoropropylene

[0049] (1) In a nitrogen atmosphere, 2,6-dichloropyridinium tetrafluoroborate (1.0 mol), chloroform solvent (300 mL), and 3,3,3-trifluoro-1-propyne (1.0 mol) were added sequentially to the reaction flask. After stirring at 60 °C for 6 hours, the Markovnikov addition synthesis reaction was completed.

[0050] (2) After the Markovnikov addition synthesis reaction is completed, the resulting mixture is cooled to room temperature, passed through a silica gel pad, and eluted with CH2Cl2 to obtain a filtrate. The filtrate is then concentrated in a vacuum to obtain 2,3,3,3-tetrafluoropropylene.

[0051] II. Examination of Important Parameters 1. Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5: Investigation of Pyridinium Tetrafluoroborate Except for the parameters in Table 1, 2,3,3,3-tetrafluoropropylene was prepared according to the method described in Section I, "Preparation Method of 2,3,3,3-Tetrafluoropropylene".

[0052] Table 1

[0053] in conclusion: (1) Analysis of the data in Table 1 shows that the fluorinating reagent is pyridinium tetrafluoroborate with the above structure, that is, as shown in Formula I, R1, R2, R3, R4 and R5 are each independently selected from hydrogen and halogen, and at least two are selected from halogen. This can avoid the use of strong bases such as sodium hydroxide as starting material or intermediates of R244bb and R245eb, reduce by-products, lower the requirements for separation process, and develop a new process route for 2,3,3,3-tetrafluoropropene. The above process route has mild reaction conditions, low product separation difficulty, and safe production.

[0054] (2) In this application, R1 and R5 are each independently selected from halogens, and R2 and R4 are selected from hydrogen, such as 2,6-dichloropyridinium tetrafluoroborate in Examples 1-4. This can simultaneously optimize the conversion rate of the reaction feedstock 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene, resulting in unexpected technical effects.

[0055] 2. Examples 2-1 to 2-6: Investigation of Solvents Except for the parameters in Table 2, 2,3,3,3-tetrafluoropropylene was prepared according to the method described in Section I, "Preparation Method of 2,3,3,3-Tetrafluoropropylene".

[0056] Table 2

[0057] in conclusion: (1) Analysis of the data in Table 2 shows that, by using the above solvents (toluene, chlorobenzene, trichlorotoluene, chloroform, 1,2-dichloroethane or acetonitrile), the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene can be optimized compared with other solvents (such as tetrahydrofuran and methyl n-butyl ether).

[0058] (2) In this application, at least one of chlorobenzene, trichlorotoluene or chloroform is preferred, and chloroform is further preferred. It can better improve the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene at the same time, which has unexpected technical effects.

[0059] 3. Examples 3-1 to 3-6: Temperature Investigation Except for the parameters in Table 3, 2,3,3,3-tetrafluoropropylene was prepared according to the method described in Section I, "Preparation Method of 2,3,3,3-Tetrafluoropropylene".

[0060] Table 3

[0061] in conclusion: Analysis of the data in Table 3 shows that the temperature range of the Marvin addition synthesis reaction is 25-100℃, preferably 50-80℃, and more preferably 60-80℃. Under mild conditions, the conversion rate of the reactant 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene can be improved.

[0062] 4. Examples 4-1 to 4-7: Investigation of Additives Example 4-1 (1) In a nitrogen atmosphere, pyridinium tetrafluoroborate (1.0 mol), additive NaBF4 (1 mol), solvent chloroform 300 mL and 3,3,3-trifluoro-1-propyne (1.0 mol) were added to the reaction flask in sequence. After stirring at 60 °C for 6 hours, the Markovnikov addition synthesis reaction was completed.

[0063] (2) After the Markovnikov addition synthesis reaction is completed, the resulting mixture is cooled to room temperature, passed through a silica gel pad, and eluted with CH2Cl2 to obtain a filtrate. The filtrate is then concentrated in a vacuum to obtain 2,3,3,3-tetrafluoropropylene.

[0064] Examples 4-2 to 4-7 Except for the parameters in Table 4, 2,3,3,3-tetrafluoropropylene was prepared according to the method in Example 4-1 above.

[0065] Table 4

[0066] in conclusion: (1) Analysis of the data in Table 4 shows that, compared with no additives, using tetrafluoroborate as an additive can optimize the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene.

[0067] (2) In this application, lithium tetrafluoroborate is preferred as an additive, which can further optimize the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne and the selectivity of the product 2,3,3,3-tetrafluoropropene. In particular, it significantly improves the conversion rate of the reaction raw material 3,3,3-trifluoro-1-propyne, and has unexpected technical effects.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for producing 2,3,3,3-tetrafluoropropene, characterized by, The preparation method comprises the following steps: The 3,3,3-trifluoro-1-propyne and a fluorinating agent are subjected to a Markovnikov addition synthesis reaction to obtain 2,3,3,3-tetrafluoropropene; The fluorinating agent comprises pyridinium tetrafluoroborate; The pyridinium tetrafluoroborate has a structural formula as shown in Formula I: Formula I; R1, R2, R3, R4 and R5 are each independently selected from hydrogen and halogen, and at least two are selected from halogen.

2. The production method according to claim 1, characterized by, R1 and R5 are each independently selected from halogen; Preferably, R2 and R4 are selected from hydrogen; Preferably, R3 is selected from H or halogen.

3. The production method according to claim 1 or 2, characterized by, The pyridinium tetrafluoroborate comprises at least one of the following compounds: 、 、 、 。 4. The production process according to any one of claims 1 to 3, characterized in that, The molar ratio of the 3,3,3-trifluoro-1-propyne to the fluorinating agent is 1: (1-3).

5. The method of any one of claims 1-4, wherein, The Markovnikov addition synthesis reaction is carried out in a solvent; Preferably, the solvent comprises at least one of toluene, chlorobenzene, trichlorobenzene, chloroform, 1,2-dichloroethane or acetonitrile, preferably at least one of chlorobenzene, trichlorobenzene or chloroform, and further preferably chloroform; Preferably, the Markovnikov addition synthesis reaction is carried out in a nitrogen atmosphere and / or an inert atmosphere.

6. The method of any one of claims 1-5, wherein, The raw material of the Markovnikov addition synthesis reaction further comprises an additive; Preferably, the additive comprises a tetrafluoroborate salt; Preferably, the additive comprises at least one of sodium tetrafluoroborate, lithium tetrafluoroborate, tetraethylammonium tetrafluoroborate or tetrabutylammonium tetrafluoroborate, and more preferably lithium tetrafluoroborate; Preferably, the molar ratio of the 3,3,3-trifluoro-1-propyne to the additive is 1: (0.1-2).

7. The method of any one of claims 1-6, wherein, The temperature of the Markovnikov addition synthesis reaction is 25-100 DEG C, preferably 50-80 DEG C, and more preferably 60-80 DEG C.

8. The production process according to any one of claims 1 to 7, characterized in that, The time of the Markovnikov addition synthesis reaction is 4-12 h.

9. The method of any one of claims 1-8, wherein, The Markovnikov addition synthesis reaction further comprises a post-treatment, and the post-treatment comprises cooling and elution after the reaction is completed to obtain a filtrate, and the solvent is removed.

10. The method of any one of claims 1-9, wherein, The preparation method comprises the following steps: (1) The 3,3,3-trifluoro-1-propyne, the pyridinium tetrafluoroborate, the additive and the solvent are mixed in a nitrogen atmosphere and / or an inert atmosphere to carry out a Markovnikov addition synthesis reaction, wherein the temperature of the Markovnikov addition synthesis reaction is 25-100 DEG C, and the time is 4-10 h; (2) After the Markovnikov addition synthesis reaction is completed, the obtained mixture is cooled and eluted to obtain a filtrate, and then the solvent is removed to obtain 2,3,3,3-tetrafluoropropene.

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