Preparation method of hexafluoroisobutylene

Abstract

The invention relates to a preparation method of hexafluoroisobutylene, and the preparation method comprises the following steps: mixing 3, 3, 3-trifluoro-2-(trifluoromethyl)-1, 2-propylene glycol, diphenyl phosphorus chloride, zinc, iodine, imidazole and a solvent under a protective atmosphere, and carrying out a reaction to obtain the hexafluoroisobutylene. According to the method, 3, 3, 3-trifluoro-2-(trifluoromethyl)-1, 2-propylene glycol, diphenyl phosphorus chloride, zinc, iodine and imidazole are used as raw materials, hexafluoroisobutene is prepared through a one-step reaction, the preparation method is simple in process route and mild in reaction condition, a solvent used in the preparation process can be recycled, pollution in the preparation process is reduced, few three wastes are generated, and the method is suitable for industrial production. And the method is environment-friendly and suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of fluorochemical synthesis technology and relates to a method for preparing hexafluoroisobutylene. Background Technology

[0002] Hexafluoroisobutylene (2-trifluoromethyl-3,3,3-trifluoro-1-propene, abbreviated as HFIB) is a multifunctional fluorinated olefin compound widely used due to its unique and excellent heat resistance, chemical resistance, low surface tension, and ozone-free properties. Its applications include the manufacture of special electrical components, semiconductor photolithography materials, electronic etching gases, refrigerants, foaming agents, and pharmaceutical intermediates. Therefore, due to its excellent multifunctionality, hexafluoroisobutylene has significant application value in multiple fields and is attracting increasing attention.

[0003] Currently, the methods for synthesizing hexafluoroisobutylene include elimination, reverse cycloaddition, halogen exchange, and decarboxylation.

[0004] US4766238A discloses a decarboxylation method using chloromethyl 2-trifluoromethyl-3,3,3-trifluorobutyrate as a raw material. In the presence of a tertiary amine, the reaction is carried out at 65°C for 3 hours to yield 76% hexafluoroisobutylene. The reaction formula is as follows:

[0005] ;

[0006] For example, REA Dear disclosed in the literature "Tetrahedron 27 (1971) 3345-3355" that hexafluoroacetone is used as a raw material to react with methyl Grignard reagent at 0℃~5℃ to produce hexafluoro-2-methyl-2-propanol. The generated hexafluoro-2-methyl-2-propanol reacts with a dehydrating agent to produce hexafluoroisopropene. The reaction formula is as follows:

[0007] ;

[0008] US4244891A discloses a reverse cycloaddition method, which uses hexafluoroacetone and ketene precursors to generate hexafluoroisopropene via cyclization, ring-opening, and decarbonylation in the range of 400℃ to 700℃, with a molar conversion rate of over 90%. The reaction formula is as follows:

[0009] ;

[0010] For example, Kawashima disclosed in the literature "Tetrahedron Lett. 38 (1997) 551-554" that a six-coordinated 1,2-oxophosphorus heterocyclic butane undergoes ring-opening at 80℃~100℃ to generate hexafluoroisobutylene with a yield of 40%. The reaction formula is as follows:

[0011] ;

[0012] Haszeldine discloses a halogen exchange method that uses 3-chloro-3,3-difluoro-2-(trifluoromethyl)-1-propene as a raw material, reacting it with antimony trifluorodichloride (SbF3Cl2) at 50°C for 3 hours to produce hexafluoroisobutylene with a yield of up to 93%. The reaction formula is as follows:

[0013] ;

[0014] Frisch disclosed a method for producing hexafluoroisobutylene in a 44% overall yield through a multi-step reaction using 1,3-dichloro-1,1,3,3-tetrafluoroacetone as a starting material, followed by sequential reactions with four reagents: methyl Grignard reagent, sulfur tetrafluoride, hydrogen fluoride, and antimony trifluoride. The reaction formula is as follows:

[0015] ;

[0016] JPS61291530A discloses a decarboxylation method that uses methyl 3,3,3-trifluoro-2-(trifluoromethyl)propionate as a raw material and reacts it with paraformaldehyde at 90°C for 3 hours in the presence of tri-n-butylamine to produce hexafluoroisobutylene with a yield of 49.1%. The reaction formula is as follows:

[0017] ;

[0018] DE3635750A1 discloses a method that uses methyl 3,3,3-trifluoro-2-(trifluoromethyl)propionate as a starting material. After chlorination, the product is reacted with pyridine at 70°C for 2 hours to yield hexafluoroisopropene in 70% yield. The reaction formula is as follows:

[0019] ;

[0020] In summary, the above-mentioned synthesis methods involve harsh reaction conditions, complex processes, and demanding equipment. Furthermore, the production process generates large amounts of liquid and solid waste, severely polluting the environment. To address these issues, new preparation methods need to be developed. Summary of the Invention

[0021] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing hexafluoroisobutylene. This method uses 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine, and imidazole as raw materials to prepare hexafluoroisobutylene through a one-step reaction. The preparation method has a simple process route, mild reaction conditions, and the solvents used in the preparation process can be recycled, reducing pollution during the preparation process. It also produces less waste, making it environmentally friendly and suitable for large-scale production.

[0022] To achieve this objective, the present invention employs the following technical solution:

[0023] This invention provides a method for preparing hexafluoroisobutylene, the method comprising the following steps:

[0024] Under a protective atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol (CAS:143471-08-3), diphenylphosphine chloride (CAS:1079-66-9), zinc, iodine, imidazole and solvent are mixed and reacted to obtain the hexafluoroisobutylene.

[0025] This invention uses 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine, and imidazole as raw materials to prepare hexafluoroisobutylene in a one-step reaction. The preparation method has a simple process route, mild reaction conditions, and the solvent used in the preparation process can be recycled, reducing pollution in the preparation process. It also produces less waste, making it environmentally friendly and suitable for large-scale production.

[0026] Specifically, the process route of the preparation method provided by this invention is as follows:

[0027] ;

[0028] In one embodiment of the present invention, the solvent includes any one or a combination of at least two of the following: dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetonitrile, benzene, toluene, chlorobenzene, nitrobenzene, p-xylene, o-xylene, m-xylene, dichloromethane, 1,2-dichloroethane, or 1,1-dichloroethane.

[0029] In one embodiment of the present invention, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to diphenylphosphine chloride is 1:0.2 to 1:5, for example, it can be 1:0.2, 1:0.5, 1:1, 1:2, 1:3, 1:4 or 1:5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In one embodiment of the present invention, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to zinc is 1:1 to 1:20, for example, it can be 1:1, 1:3, 1:5, 1:8, 1:10, 1:12, 1:15, 1:18 or 1:20, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] In one embodiment of the present invention, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:0.2 to 1:5, for example, it can be 1:0.2, 1:0.5, 1:1, 1:2, 1:3, 1:4 or 1:5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] In one embodiment of the present invention, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to the imidazole is 1:0.5 to 1:9, for example, it can be 1:0.5, 1:1, 1:2, 1:4, 1:5, 1:6, 1:8 or 1:9, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] In one embodiment of the present invention, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine and imidazole are used as raw materials; the mass ratio of the solvent to the raw materials is 1:1 to 6:1, for example, it can be 1:1, 2:1, 3:1, 4:1, 5:1 or 6:1, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] In one embodiment of the present invention, the reaction temperature is 20°C to 120°C, for example, it can be 20°C, 40°C, 60°C, 80°C, 100°C or 120°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] In one embodiment of the present invention, the reaction time is 1h to 24h, for example, it can be 1h, 2h, 4h, 6h, 8h, 9h, 12h, 16h or 24h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] The preparation method provided by the present invention also includes purification after the reaction. The present invention does not limit the specific purification method, as long as the purification effect can be achieved.

[0037] As a preferred embodiment of the preparation method provided by the present invention, the preparation method includes the following steps:

[0038] Under a nitrogen atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine, imidazole and solvent are mixed and reacted at 60℃~120℃ for 6h~24h to obtain the hexafluoroisobutylene.

[0039] The solvent includes any one or a combination of at least two of the following: dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetonitrile, benzene, toluene, chlorobenzene, nitrobenzene, p-xylene, o-xylene, m-xylene, dichloromethane, 1,2-dichloroethane, or 1,1-dichloroethane.

[0040] The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to diphenylphosphine chloride is 1:1 to 1:5; the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to zinc is 1:8 to 1:20; the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:1 to 1:5; and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:3 to 1:9.

[0041] The raw materials are 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine and imidazole; the mass ratio of the solvent to the raw materials is 1:1 to 6:1.

[0042] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The present invention uses 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine and imidazole as raw materials to prepare hexafluoroisobutylene in one step. The preparation method has a simple process route, mild reaction conditions, and the solvent used in the preparation process can be recycled, which reduces the pollution in the preparation process and produces less "three wastes", which is environmentally friendly and suitable for large-scale production.

[0045] (2) The reagents used in the preparation method provided by the present invention are all conventional reagents, which are inexpensive and readily available on the market, and have obvious cost advantages;

[0046] (3) The preparation method provided by the present invention is easy to separate the raw materials and the products generated by the reaction, and the purification process is simple. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0048] The "range" disclosed in this invention can be defined in the form of 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 the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning 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 specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" 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 "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0049] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0050] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0051] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0052] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0053] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0054] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0055] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0056] In this invention, "optional" means that something is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0057] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0058] Example 1

[0059] This embodiment provides a method for preparing hexafluoroisobutylene, the method comprising the following steps:

[0060] Under a nitrogen atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol (100 g, 0.504 mol), diphenylphosphine chloride (222.79 g, 1.01 mol), zinc (330.09 g, 5.05 mol), iodine (256.29 g, 1.01 mol), imidazole (137.49 g, 2.02 mol), and solvent (toluene, 2000 mL) were mixed and reacted at 80 °C for 10 h. After vacuum drying of toluene, crude hexafluoroisobutylene was obtained, and purified to obtain the hexafluoroisobutylene.

[0061] Example 2

[0062] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:0.5:2:2:10, the rest is the same as in Example 1.

[0063] Example 3

[0064] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:1:2:2:10, the rest is the same as in Example 1.

[0065] Example 4

[0066] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:2:2:2:10, the rest is the same as in Example 1.

[0067] Example 5

[0068] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:3:2:2:10, the rest is the same as in Example 1.

[0069] Example 6

[0070] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:6:2:2:10, the rest is the same as in Example 1.

[0071] Example 7

[0072] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:9:2:2:10, the rest is the same as in Example 1.

[0073] Example 8

[0074] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:0.2:2:10, the rest is the same as in Example 1.

[0075] Example 9

[0076] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:0.4:2:10, the rest is the same as in Example 1.

[0077] Example 10

[0078] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:0.8:2:10, the rest is the same as in Example 1.

[0079] Example 11

[0080] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:1:2:10, the rest is the same as in Example 1.

[0081] Example 12

[0082] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:1.5:2:10, the rest is the same as in Example 1.

[0083] Example 13

[0084] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:2.5:2:10, the rest is the same as in Example 1.

[0085] Example 14

[0086] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:5:2:10, the rest is the same as in Example 1.

[0087] Example 15

[0088] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:2:0.2:10, the rest is the same as in Example 1.

[0089] Example 16

[0090] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:2:0.4:10, the rest is the same as in Example 1.

[0091] Example 17

[0092] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:2:0.8:10, the rest is the same as in Example 1.

[0093] Example 18

[0094] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:2:1:10, the rest is the same as in Example 1.

[0095] Example 19

[0096] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:2:1.5:10, the rest is the same as in Example 1.

[0097] Example 20

[0098] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:2:2.5:10, the rest is the same as in Example 1.

[0099] Example 21

[0100] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:2:5:10, the rest is the same as in Example 1.

[0101] Example 22

[0102] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:2:2:1, the rest is the same as in Example 1.

[0103] Example 23

[0104] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:2:2:2, the rest is the same as in Example 1.

[0105] Example 24

[0106] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:2:2:4, the rest is the same as in Example 1.

[0107] Example 25

[0108] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:2:2:6, the rest is the same as in Example 1.

[0109] Example 26

[0110] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:2:2:8, the rest is the same as in Example 1.

[0111] Example 27

[0112] This embodiment provides a method for preparing hexafluoroisobutylene. Except for adjusting the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder to 1:4:2:2:15, the rest is the same as in Example 1.

[0113] Example 28

[0114] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, imidazole, diphenylphosphine chloride, iodine, and zinc powder being adjusted to 1:4:2:2:20, the rest is the same as in Example 1.

[0115] Example 29

[0116] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 20°C.

[0117] Example 30

[0118] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 40°C.

[0119] Example 31

[0120] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 60°C.

[0121] Example 32

[0122] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 100°C.

[0123] Example 33

[0124] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 120°C.

[0125] Example 34

[0126] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 1 hour.

[0127] Example 35

[0128] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 2 hours.

[0129] Example 36

[0130] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 4 hours.

[0131] Example 37

[0132] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 6 hours.

[0133] Example 38

[0134] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 8 hours.

[0135] Example 39

[0136] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 12 hours.

[0137] Example 40

[0138] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 16 hours.

[0139] Example 41

[0140] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 24 hours.

[0141] Performance Characterization

[0142] The yield of hexafluoroisobutylene in the preparation method provided in the above embodiments was statistically analyzed, and the results are shown in Table 1.

[0143] Table 1

[0144]

[0145] According to Table 1, the following points can be observed:

[0146] (1) Comprehensive analysis of Examples 1 and 2 to 7 shows that when the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is higher than 1:4, the reaction of the raw material 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol is incomplete, resulting in a low yield of hexafluoroisobutylene. When the reverse molar ratio is lower than 1:4, the yield of hexafluoroisobutylene does not change significantly, but it will cause a waste of imidazole.

[0147] (2) Comprehensive analysis of Examples 1 and 8 to 14 shows that when the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to diphenylphosphine chloride is higher than 1:2, the reaction of the raw material 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol is incomplete, resulting in a low yield of hexafluoroisobutylene. When the reverse molar ratio is lower than 1:2, it has no significant effect on the yield of hexafluoroisobutylene, but it will result in a surplus of diphenylphosphine chloride, which will be wasted.

[0148] (3) Comprehensive analysis of Examples 1 and 15 to 21 shows that when the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is higher than 1:2, the reaction of the raw material 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol is incomplete, resulting in a low yield of hexafluoroisobutylene. When the reverse molar ratio is lower than 1:2, the yield of hexafluoroisobutylene does not change significantly, but the excessive addition of iodine will cause a waste of resources.

[0149] (4) Comprehensive analysis of Examples 1 and 22 to 28 shows that when the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to zinc is higher than 1:10, the reaction of the raw material 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol is incomplete, resulting in a low yield of hexafluoroisobutylene. When the reverse molar ratio is lower than 1:10, the yield of hexafluoroisobutylene does not change significantly, but it will waste zinc resources.

[0150] (5) Comprehensive analysis of Examples 1 and 29 to 33 shows that the choice of reaction temperature affects the yield of hexafluoroisobutylene. When the reaction temperature is too low (below 80°C), the raw material 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol will not react or react incompletely, resulting in a decrease in the yield of hexafluoroisobutylene. When the reaction temperature is too high (above 80°C), there is no significant effect on the yield of hexafluoroisobutylene, but it will cause energy waste.

[0151] (6) Comprehensive analysis of Examples 1 and 34 to 41 shows that when the reaction time is less than 10 hours, there is a surplus of raw materials and the yield of hexafluoroisobutylene is significantly reduced; when the reaction time is more than 10 hours, the yield of hexafluoroisobutylene does not change significantly, but it will cause energy waste.

[0152] In summary, this invention uses 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine, and imidazole as raw materials to prepare hexafluoroisobutylene in a one-step reaction. The preparation method has a simple process route, mild reaction conditions, and the solvents used in the preparation process can be recycled, reducing pollution during the preparation process. It also produces less waste, making it environmentally friendly and suitable for large-scale production.

[0153] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing hexafluoroisobutylene, characterized in that, The preparation method includes the following steps: Under a protective atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine, imidazole, and solvent are mixed and reacted to obtain the hexafluoroisobutylene.

2. The preparation method according to claim 1, characterized in that, The solvent includes any one or a combination of at least two of the following: dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetonitrile, benzene, toluene, chlorobenzene, nitrobenzene, p-xylene, o-xylene, m-xylene, dichloromethane, 1,2-dichloroethane, or 1,1-dichloroethane.

3. The preparation method according to claim 1, characterized in that, The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to diphenylphosphine chloride is 1:0.2 to 1:

5.

4. The preparation method according to claim 1, characterized in that, The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to zinc is 1:1 to 1:

20.

5. The preparation method according to claim 1, characterized in that, The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:0.2 to 1:

5.

6. The preparation method according to claim 1, characterized in that, The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to the imidazole is 1:0.5 to 1:

9.

7. The preparation method according to claim 1, characterized in that, The raw materials are 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine and imidazole. The mass ratio of the solvent to the raw material is 1:1 to 6:

1.

8. The preparation method according to claim 1, characterized in that, The reaction temperature is 20℃~120℃.

9. The preparation method according to claim 1, characterized in that, The reaction time is 1 hour to 24 hours.

10. The preparation method according to any one of claims 1 to 9, characterized in that, The preparation method includes the following steps: Under a nitrogen atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine, imidazole and solvent are mixed and reacted at 60℃~120℃ for 6h~24h to obtain the hexafluoroisobutylene. The solvent includes any one or a combination of at least two of the following: dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetonitrile, benzene, toluene, chlorobenzene, nitrobenzene, p-xylene, o-xylene, m-xylene, dichloromethane, 1,2-dichloroethane, or 1,1-dichloroethane. The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to diphenylphosphine chloride is 1:1 to 1:5; the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to zinc is 1:8 to 1:20; the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:1 to 1:5; and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:3 to 1:

9. The raw materials are 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, diphenylphosphine chloride, zinc, iodine and imidazole; the mass ratio of the solvent to the raw materials is 1:1 to 6:1.

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