A process for the preparation of hexafluoroisobutene

Abstract

The present application relates to a kind of preparation methods of hexafluoroisobutene, the preparation method includes the following steps: under the condition of protective atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenyl phosphine, iodine, imidazole and solvent are mixed, reaction is carried out, and the hexafluoroisobutene of reactant is purified to obtain.The process route of preparation method provided by the present application is simple, reaction condition is mild, and solvent used in preparation process can be recycled, reduce pollution in preparation process, and "three wastes" are less, environment-friendly, suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fluorinated chemicals, and relates to a preparation method of hexafluoroisobutene. BACKGROUND

[0002] Hexafluoroisobutene (2-trifluoromethyl-3,3,3-trifluoro-1-propene, abbreviated as HFIB) is a multifunctional fluorine-containing olefin compound. Due to its unique excellent heat resistance, chemical resistance, low surface tension, non-ozone depletion and other physical and chemical properties, it is widely used. Its application range includes special electrical appliance part manufacturing, semiconductor photoetching material, electronic etching gas, refrigerant, foaming agent and pharmaceutical intermediate, etc. Therefore, hexafluoroisobutene has important application value in many fields due to its excellent multifunctionality, and therefore it is increasingly concerned by people, and its preparation process is increasingly valued.

[0003] In the prior art, the preparation methods of hexafluoroisobutene include the following four types:

[0004] (1) Elimination method: US4766238A discloses a method of using 2-trifluoromethyl-3,3,3-trifluorobutyric acid chloromethyl ester as raw material, in the presence of a tertiary amine (preferably tributylamine), the reaction temperature is 65℃, and the reaction time is 3 hours, and 76% of hexafluoroisobutene can be obtained, and the reaction formula is as follows:

[0005] ;

[0006] For example, R.E.A. Dear discloses in the document "Tetrahedron 27 (1971) 3345-3355" that hexafluoro-2-methyl-2-propanol is generated by reacting hexafluoroacetone with methyl Grignard reagent at 0℃~5℃, and the generated hexafluoro-2-methyl-2-propanol is reacted with a dehydrating agent (such as SF4, PCl5 or ClCN) to generate hexafluoroisopropylene, and the reaction formula is as follows:

[0007] ;

[0008] (2) Reverse cycloaddition method: US4244891A discloses a method of using hexafluoroacetone and an ethenone precursor (acetic anhydride, acetone, acetic acid, isopropyl acetoacetate, acetylacetone or diketone) to generate hexafluoroisopropylene through cyclization, ring-opening and decarboxylation at 400℃~700℃, and the molar conversion rate can reach more than 90%, and the reaction formula is as follows:

[0009] ;

[0010] For example, Kawashima disclosed in the document "Tetrahedron Lett. 38 (1997) 551-554" that hexacoordinated 1,2-oxaphospholane opens at 80-100°C to generate hexafluoroisobutene with a yield of 40%, and the reaction formula is as follows:

[0011]

[0012] (3) Halogen exchange method (Swarts reaction): Haszeldine disclosed a method of taking 3-chloro-3,3-difluoro-2-(trifluoromethyl)-1-propene as a raw material, reacting with antimony trifluoride dichloride (SbF3Cl2) at 50°C for 3 hours to generate hexafluoroisobutene with a yield of 93%, and the reaction formula is as follows:

[0013]

[0014] For example, Frisch disclosed a method of taking 1,3-dichloro-1,1,3,3-tetrafluoroacetone as a raw material, sequentially reacting with methyl Grignard reagent, sulfur tetrafluoride, hydrogen fluoride and antimony trifluoride to generate hexafluoroisobutene with a total yield of 44% through a multi-step reaction, and the reaction formula is as follows:

[0015]

[0016] (4) Decarboxylation method: JPS61291530A disclosed a method of taking methyl 3,3,3-trifluoro-2-(trifluoromethyl)propionate as a raw material, reacting with polyformaldehyde in the presence of tri-n-butylamine at 90°C for 3 hours to generate hexafluoroisobutene with a yield of 49.1%, and the reaction formula is as follows:

[0017]

[0018] For example, DE3635750A1 disclosed a method of taking methyl 3,3,3-trifluoro-2-(trifluoromethyl)propionate as a raw material, after chlorination, the obtained product was added dropwise with pyridine at 70°C and reacted for 2 hours to obtain hexafluoroisobutene with a yield of 70%, and the reaction formula is as follows:

[0019]

[0020] In summary, the above-mentioned preparation methods have harsh reaction conditions, complex synthesis processes, and high requirements for the preparation equipment; in addition, a large amount of liquid waste and solid waste is generated in the production process, which seriously pollutes the environment. In order to solve the above problems, a new preparation method needs to be developed. SUMMARY

[0021] ​​​​​In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing hexafluoroisobutylene. The preparation method has a simple process route, mild reaction conditions, and the solvent used in the preparation process can be recycled, which reduces pollution in the preparation process. It also produces less waste, is environmentally friendly, and is suitable for large-scale production.

[0022] To achieve this objective, the present invention adopts 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), triphenylphosphine (CAS:603-35-0), iodine (CAS:12190-71-5), imidazole (CAS:288-32-4) and solvent were mixed and reacted. The reactants were purified to obtain the hexafluoroisobutylene.

[0025] The method for preparing hexafluoroisobutylene provided by this invention not only has a simple process route and mild reaction conditions, but also reduces pollutant emissions and the generation of "three wastes" by recycling solvents, thus possessing both environmental friendliness and adaptability to large-scale production. The reaction follows a "nucleophilic substitution-base-promoted elimination" pathway. First, triphenylphosphine reacts with iodine to form a nucleophilic iodinated complex, which promotes the substitution of the hydroxyl group of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol by the iodide ion in the complex to generate an iodinated product. Then, under the action of imidazole (an organic base), the iodinated product undergoes an E2 elimination reaction to form a carbon-carbon double bond to generate the target product. The solvent only plays a role in dissolving and dispersing, so it can be recycled, further supporting the advantages of environmental protection and efficient production.

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

[0027] ;

[0028] In some embodiments, the reaction temperature is 20°C to 120°C.

[0029] In some embodiments, the reaction time is 1 hour to 24 hours.

[0030] In some embodiments, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:0.5 to 1:10.

[0031] In some embodiments, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:0.5 to 1:10.

[0032] In some embodiments, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to the imidazole is 1:0.5 to 1:20.

[0033] In some embodiments, 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.

[0034] In some embodiments, the raw materials are 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine and imidazole;

[0035] The mass ratio of the solvent to the raw material is 0.5:1 to 6:1.

[0036] In some embodiments, the protective gas used in the protective atmosphere conditions includes nitrogen and / or an inert gas.

[0037] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0038] Under a nitrogen atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine, imidazole and solvent were mixed and reacted. The reactants were purified to obtain the hexafluoroisobutylene.

[0039] The reaction temperature is 80℃~120℃, and the time is 6h~24h;

[0040] The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:3 to 1:10.

[0041] The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:2 to 1:10.

[0042] The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to the imidazole is 1:6 to 1:20.

[0043] 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.

[0044] The solvent is used as a raw material, consisting of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine and imidazole; the mass ratio of the solvent to the raw material is 0.5:1 to 6:1.

[0045] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) 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;

[0048] (2) The preparation method provided by the present invention has a simple process route, mild reaction conditions, and no harsh conditions such as high temperature and high pressure;

[0049] (3) The preparation method provided by the present invention is easy to operate, the solvent used in the preparation process can be recycled, reducing pollution in the preparation process, and the "three wastes" are less, which is environmentally friendly and suitable for large-scale production;

[0050] (4) The raw materials and products generated by the reaction in the preparation method provided by the present invention are easy to separate, and the purification process is simple. Detailed Implementation

[0051] 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.

[0052] 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.

[0053] 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.

[0054] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0055] 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.

[0056] 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.

[0057] 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."

[0058] 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.

[0059] 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.

[0060] 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.

[0061] This invention provides a method for preparing hexafluoroisobutylene, the method comprising the following steps:

[0062] Under a protective atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol (CAS:143471-08-3), triphenylphosphine (CAS:603-35-0), iodine (CAS:12190-71-5), imidazole (CAS:288-32-4) and solvent were mixed and reacted. The reactants were purified to obtain the hexafluoroisobutylene.

[0063] The method for preparing hexafluoroisobutylene provided by this invention not only has a simple process route and mild reaction conditions, but also reduces pollutant emissions and the generation of "three wastes" by recycling solvents, thus possessing both environmental friendliness and adaptability to large-scale production. The reaction follows a "nucleophilic substitution-base-promoted elimination" pathway. First, triphenylphosphine reacts with iodine to form a nucleophilic iodinated complex, which promotes the substitution of the hydroxyl group of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol by the iodide ion in the complex to generate an iodinated product. Then, under the action of imidazole (an organic base), the iodinated product undergoes an E2 elimination reaction to form a carbon-carbon double bond to generate the target product. The solvent only plays a role in dissolving and dispersing, so it can be recycled, further supporting the advantages of environmental protection and efficient production.

[0064] Specifically, the process route of the preparation method of the present invention is as follows:

[0065] .

[0066] In some embodiments, the reaction temperature is 20°C to 120°C, for example, 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.

[0067] In some embodiments, 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.

[0068] In some embodiments, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:0.5 to 1:10, for example, it can be 1:0.5, 1:1, 1:2, 1:4, 1:5, 1:6, 1:8 or 1:10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0069] In some embodiments, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:0.5 to 1:10, for example, it can be 1:0.5, 1:1, 1:2, 1:4, 1:5, 1:6, 1:8 or 1:10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0070] In some embodiments, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to the imidazole is 1:0.5 to 1:20, for example, it can be 1:0.5, 1:1, 1:2, 1:4, 1:5, 1:6, 1:8, 1:10, 1:12, 1:15, 1:16, 1:18 or 1:20, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0071] In some embodiments, the solvent comprises any one or a combination of at least two of 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. Typical but non-limiting combinations include a combination of dimethyl sulfoxide, N,N-dimethylformamide, and tetrahydrofuran; a combination of acetonitrile, benzene, toluene, and chlorobenzene; or a combination of dichloromethane and 1,1-dichloroethane.

[0072] In some embodiments, the raw materials are 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine and imidazole;

[0073] The mass ratio of the solvent to the raw material is 0.5:1 to 6:1, for example, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1 or 6:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0074] In some embodiments, the protective gas used in the protective atmosphere conditions includes nitrogen and / or an inert gas.

[0075] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0076] Under a nitrogen atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine, imidazole and solvent were mixed and reacted. The reactants were purified to obtain the hexafluoroisobutylene.

[0077] The reaction temperature is 80℃~120℃, and the time is 6h~24h;

[0078] The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:3 to 1:10.

[0079] The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:2 to 1:10.

[0080] The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to the imidazole is 1:6 to 1:20.

[0081] 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.

[0082] The solvent is used as a raw material, consisting of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine and imidazole; the mass ratio of the solvent to the raw material is 0.5:1 to 6:1.

[0083] Example 1

[0084] This embodiment provides a method for preparing hexafluoroisobutylene, including the following steps:

[0085] In a nitrogen atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol (150 g, 0.757 mol), imidazole (412.47 g, 6.06 mol), triphenylphosphine (794.57 g, 3.03 mol), iodine (768.87 g, 3.03 mol), and solvent (toluene, 2000 mL) were mixed in a 5000 mL thick-walled pressure-resistant bottle. The mixture was heated to 90 °C and reacted for 10 h. The solvent was then evaporated under vacuum. The crude hexafluoroisobutylene obtained was purified to give hexafluoroisobutylene (114.7 g, purity 92.3 wt%).

[0086] In this embodiment, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:4; the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:4; and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:8.

[0087] Example 2

[0088] This embodiment provides a method for preparing hexafluoroisobutylene, except that the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:0.5, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:8, all other methods are the same as in Example 1.

[0089] Example 3

[0090] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:1, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:8, all other methods are the same as in Example 1.

[0091] Example 4

[0092] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:2, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:8, all other methods are the same as in Example 1.

[0093] Example 5

[0094] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:3, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:8, all other methods are the same as in Example 1.

[0095] Example 6

[0096] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:5, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:8, all other methods are the same as in Example 1.

[0097] Example 7

[0098] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:10, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:8, all other methods are the same as in Example 1.

[0099] Example 8

[0100] This embodiment provides a method for preparing hexafluoroisobutylene, except that the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:0.5, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:8, all other methods are the same as in Example 1.

[0101] Example 9

[0102] This embodiment provides a method for preparing hexafluoroisobutylene, except that the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:1, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:8, all other aspects are the same as in Example 1.

[0103] Example 10

[0104] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:2, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:8, all other methods are the same as in Example 1.

[0105] Example 11

[0106] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:3, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:8, all other methods are the same as in Example 1.

[0107] Example 12

[0108] This embodiment provides a method for preparing hexafluoroisobutylene, except that the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:5, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:8, all other aspects are the same as in Example 1.

[0109] Example 13

[0110] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:10, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:8, all other methods are the same as in Example 1.

[0111] Example 14

[0112] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:0.5.

[0113] Example 15

[0114] This embodiment provides a method for preparing hexafluoroisobutylene. Except that the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:1, all other methods are the same as in Example 1.

[0115] Example 16

[0116] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:2, all other methods are the same as in Example 1.

[0117] Example 17

[0118] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:4, all other methods are the same as in Example 1.

[0119] Example 18

[0120] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:6, all other methods are the same as in Example 1.

[0121] Example 19

[0122] This embodiment provides a method for preparing hexafluoroisobutylene. Except for the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine being 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine being 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole being 1:10, all other methods are the same as in Example 1.

[0123] Example 20

[0124] This embodiment provides a method for preparing hexafluoroisobutylene, except that the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:4, the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:4, and the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is 1:20, all other aspects are the same as in Example 1.

[0125] Example 21

[0126] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 20°C.

[0127] Example 22

[0128] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 40°C.

[0129] Example 23

[0130] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 60°C.

[0131] Example 24

[0132] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 80°C.

[0133] Example 25

[0134] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 100°C.

[0135] Example 26

[0136] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction temperature is 120°C.

[0137] Example 27

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

[0139] Example 28

[0140] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 2 hours.

[0141] Example 29

[0142] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 4 hours.

[0143] Example 30

[0144] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 6 hours.

[0145] Example 31

[0146] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 8 hours.

[0147] Example 32

[0148] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 12 hours.

[0149] Example 33

[0150] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 16 hours.

[0151] Example 34

[0152] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the reaction time is 24 hours.

[0153] Example 35

[0154] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the mass ratio of solvent to raw material is 0.5:1.

[0155] Example 36

[0156] This embodiment provides a method for preparing hexafluoroisobutylene, which is the same as in Example 1 except that the mass ratio of solvent to raw material is 6:1.

[0157] Performance Characterization

[0158] Based on 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, the yields of hexafluoroisobutylene prepared by the methods provided in the above examples are shown in Table 1.

[0159] Table 1

[0160]

[0161] According to Table 1, the following points can be observed:

[0162] (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 triphenylphosphine is low, 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 molar ratio is high, the yield of hexafluoroisobutylene does not change significantly, but it will cause a waste of triphenylphosphine.

[0163] (2) Comprehensive analysis of Examples 1 and 8 to 13 shows that when the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is low, 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 molar ratio is high, it has no significant effect on the yield of hexafluoroisobutylene, but it will cause a waste of iodine resources.

[0164] (3) Comprehensive analysis of Examples 1 and 14 to 20 shows that when the molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to imidazole is low, 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 molar ratio is high, the yield of hexafluoroisobutylene does not change significantly, but the excessive addition of imidazole will cause a waste of resources.

[0165] (4) Comprehensive analysis of Examples 1 and Examples 21 to 26 shows that the reaction temperature affects the yield of hexafluoroisobutylene. When the reaction temperature is low, the raw materials will not react completely, resulting in a decrease in the yield of hexafluoroisobutylene. When the reaction temperature is high, there is no significant effect on the yield of hexafluoroisobutylene, but it will cause energy waste.

[0166] (5) Comprehensive analysis of Examples 1 and 27 to 34 shows that when the reaction time is short, there is a surplus of raw materials and the yield of hexafluoroisobutylene is significantly reduced; when the reaction time is long, the yield of hexafluoroisobutylene does not change significantly, but it will cause energy waste.

[0167] In summary, the method for preparing hexafluoroisobutylene provided by this invention not only has a simple process route and mild reaction conditions, but also reduces pollutant emissions and the generation of "three wastes" by recycling solvents, thus possessing both environmental friendliness and adaptability to large-scale production. The reaction follows a "nucleophilic substitution-base-promoted elimination" pathway. First, triphenylphosphine reacts with iodine to form a nucleophilic iodinated complex, which promotes the substitution of the hydroxyl group of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol by the iodide ion in the complex to generate an iodinated product. Then, under the action of imidazole (an organic base), the iodinated product undergoes an E2 elimination reaction to form a carbon-carbon double bond to generate the target product. The solvent only plays a role in dissolving and dispersing, so it can be recycled, further supporting the advantages of environmental protection and efficient production.

[0168] 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, triphenylphosphine, iodine, imidazole, and solvent were mixed and reacted. The reactants were purified to obtain the hexafluoroisobutylene.

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

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

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 triphenylphosphine is 1:0.5 to 1:

10.

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 1:0.5 to 1:

10.

6. The preparation method according to claim 4 or 5, 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:

20.

7. 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.

8. The preparation method according to claim 1 or 7, characterized in that, Using 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine and imidazole as raw materials; The mass ratio of the solvent to the raw material is 0.5:1 to 6:

1.

9. The preparation method according to claim 1, characterized in that, The protective gases used in the protective atmosphere conditions include nitrogen and / or inert gases.

10. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: Under a nitrogen atmosphere, 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine, imidazole and solvent were mixed and reacted. The reactants were purified to obtain the hexafluoroisobutylene. The reaction temperature is 80℃~120℃, and the time is 6h~24h; The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to triphenylphosphine is 1:3 to 1:

10. The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to iodine is 1:2 to 1:

10. The molar ratio of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol to the imidazole is 1:6 to 1:

20. 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 solvent is used as a raw material, consisting of 3,3,3-trifluoro-2-(trifluoromethyl)-1,2-propanediol, triphenylphosphine, iodine and imidazole; the mass ratio of the solvent to the raw material is 0.5:1 to 6:1.

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