Preparation method of phosphorus trifluoride

Abstract

The invention belongs to the field of organic phosphorus chemistry and phosphorus chemical industry, and particularly relates to a preparation method of phosphorus trifluoride, which comprises the following step: under the protection of inert gas, reacting phosphorus trichloride with ionic liquid to obtain the phosphorus trifluoride. The ionic liquid is used as a fluorine source, dangerous raw materials such as hydrogen fluoride and metal fluoride are avoided, the ionic liquid can be used as the fluorine source and can also be used as a reaction solvent, and the reaction activity of phosphorus trichloride and the ionic liquid is greatly improved. The method has the advantages of mild reaction conditions, low reaction temperature, short reaction time, no generation of other by-product gases in the reaction system, simple post-treatment operation, and high reaction yield and purity.

Description

Technical Field

[0001] The invention belongs to the fields of organophosphorus chemistry and phosphorus chemical industry, and particularly relates to a method for preparing phosphorus trifluoride. Background Art

[0002] Phosphorus trifluoride (PF3) is an important inorganic compound. It is a colorless, odorless gas at room temperature and pressure, and a colorless, transparent liquid in its liquid state. Its melting point is -151.3°C, boiling point is -101.2°C, density is 3.907 g / L, molecular weight is 87.97, and it is soluble in ethanol. Phosphorus trifluoride is widely used in the electronics industry, battery manufacturing, polymer materials, and organic synthesis. In semiconductor manufacturing, phosphorus trifluoride can be used as a dopant to dope semiconductor materials such as silicon, thereby altering their electronic properties and significantly improving semiconductor performance. In the field of polymer materials, phosphorus trifluoride can be used as a reactant to synthesize fluorinated organic dithiophosphates and terephthalate esters, polymer materials with excellent corrosion resistance. In organic synthesis, phosphorus trifluoride plays an important role as a reagent in the formation of fluorohydrocarbons, fluorination of aromatic compounds, and reactions of amines with anhydrides.

[0003] At present, the methods for synthesizing phosphorus trifluoride in the prior art mainly include: 1) Element reaction method. Phosphorus compounds react directly with fluorine to produce phosphorus trifluoride. The reaction process is as follows: . However, the amount of fluorine used in the above method needs to be precisely controlled. If the fluorine is insufficient, the reaction may be incomplete; and if the fluorine is excessive, it may trigger side reactions and generate PF5 or other unnecessary products, affecting the selectivity and yield of the reaction. In addition, although the reaction principle of this method is relatively simple and directly utilizes the chemical reaction between elements. Its disadvantage is that due to the strong oxidizing property of fluorine gas and its very active chemical properties, it has high requirements for reaction conditions and requires corrosion-resistant professional equipment and precise operating procedures to ensure the safety, efficiency and selectivity of the reaction.

[0004] 2) Double decomposition reaction method. Phosphorus trihalide reacts with a fluorination agent (such as hydrogen fluoride, sodium fluoride, ammonium fluoride, etc.) to produce phosphorus trifluoride and the corresponding hydrogen halide gas (hydrogen chloride, hydrogen bromide, hydrogen fluoride).

[0005] For example, CN117228643A discloses a method for preparing electronic-grade phosphorus trifluoride. Under an inert atmosphere, phosphorus trichloride is first added to a reactor and heated to a temperature of 40°C-60°C for 20-50 minutes. Anhydrous hydrogen fluoride is then slowly introduced from the bottom of the reactor to allow for a thorough reaction, generating phosphorus trifluoride, which is then directly condensed and collected. Finally, distillation and purification are performed to produce electronic-grade phosphorus trifluoride. However, this method has drawbacks such as high equipment corrosion (HF is highly corrosive) and low reaction conversion rates.

[0006] CN101955173A discloses a technology for preparing phosphorus trifluoride by reacting phosphorus trichloride with zinc fluoride. Phosphorus trichloride and zinc fluoride react in a reactor at 140 - 150 °C. This method has low reaction activity, a long reaction time, requires the use of hydrogen fluoride, has high requirements for reaction equipment, and is not easy to scale up production.

[0007] CN117163925A discloses a method for preparing phosphorus trifluoride, using an organic solution of phosphorus triiodide and a metal fluoride salt. The reaction temperature is relatively high, 270 - 400 °C, a large amount of organic solvents are used, generating a large amount of three wastes, and the production cost is relatively high.

[0008] CN118723947A discloses a method for preparing phosphorus trifluoride. Under an inert atmosphere, a fluoride salt and phosphorus trichloride are mixed and reacted to obtain phosphorus trifluoride. However, the post-treatment of this method is relatively cumbersome, and the yield and purity are relatively low.

[0009] Aiming at the problems existing in the prior art such as high reaction temperature, long reaction time, environmental pollution, low yield and purity, there is an urgent need to develop a new method for preparing phosphorus trifluoride. Summary of the Invention

[0010] The purpose of the present invention is to provide a method for preparing phosphorus trifluoride to solve the problems existing in the prior art such as high reaction temperature, long reaction time, environmental pollution, low yield and purity. To solve the above technical problems, the present invention provides the following technical solutions: A method for preparing phosphorus trifluoride, comprising the following steps: Under the protection of an inert gas, react phosphorus trichloride with an ionic liquid to obtain phosphorus trifluoride; The structural formula of the ionic liquid is: , or .

[0011] In some embodiments, the inert gas is selected from one or more of nitrogen, helium, neon, and argon.

[0012] In some embodiments, the reaction temperature is 30 - 50 °C and the reaction time is 0.5 - 5 h.

[0013] In some embodiments, the molar ratio of phosphorus trichloride to the ionic liquid is 1:(3 - 10).

[0014] In some embodiments, during the reaction process of this method, phosphorus trifluoride gas is continuously generated, condensed and collected to obtain a liquid product of phosphorus trifluoride.

[0015] In some embodiments, the temperature for condensation collection is -140 to -120 °C.

[0016] In some embodiments, the following steps are included: Under nitrogen protection, phosphorus trichloride is added to the reactor, and then the ionic liquid is slowly added. After addition, the mixture is heated to 40 °C and stirred for reaction for 1 h. Phosphorus trifluoride gas will be continuously generated during the reaction process, and the liquid-phase product of phosphorus trifluoride is obtained by condensation collection at -120 °C.

[0017] In some embodiments, under nitrogen protection, phosphorus trichloride is added to the reactor, and then the ionic liquid is slowly added. After addition, the mixture is heated to 40 °C and stirred for reaction for 1 h. Phosphorus trifluoride gas will be continuously generated during the reaction process, and the liquid-phase product of phosphorus trifluoride is obtained by condensation collection at -120 °C.

[0018] In some embodiments, under nitrogen protection, phosphorus trichloride is added to the reactor, and then the ionic liquid is slowly added. After addition, the mixture is heated to 40 °C and stirred for reaction for 1 h. Phosphorus trifluoride gas will be continuously generated during the reaction process, and the liquid-phase product of phosphorus trifluoride is obtained by condensation collection at -120 °C.

[0019] The present invention has achieved the following beneficial effects: 1) The present invention uses an ionic liquid as a fluorine source, avoiding the use of dangerous raw materials such as hydrogen fluoride and metal fluorides. Moreover, the ionic liquid can not only be used as a fluorine source but also as a reaction solvent, greatly enhancing the reaction activity between phosphorus trichloride and the ionic liquid.

[0020] 2) The reaction conditions of the present invention are mild, with a low reaction temperature and a short reaction time. Also, no other by-product gases are generated in this reaction system, and the post-treatment operation is simple. The reaction yield of phosphorus trifluoride is as high as over 96%, and the purity is as high as 99.7%.

[0021] 3) The feeding amount of the raw materials in the present invention reaches the kilogram level, and still can maintain a high yield and purity, being suitable for large-scale industrial production. Specific Embodiments The embodiments of the present invention are described in detail below. The embodiments are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0023] The endpoints and any values within the scope of the present invention are not limited to the exact scope or value. These scopes or values should be understood to include values close to these scopes or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. The present invention does not limit the source of the raw materials used. Unless otherwise specified, the raw materials used in the present invention are all ordinary commercially available products in this technical field.

[0024] Example 1 Under nitrogen protection, phosphorus trichloride (2.74 kg, 20.0 mol) was added to the reactor, and then ionic liquid was slowly added (12.88 kg, 80.0 mol). After addition, the mixture was heated to 40 °C and stirred for 1 h. Phosphorus trifluoride gas was continuously generated during the reaction, and the phosphorus trifluoride gas was condensed and collected at -120 °C to obtain a liquid phosphorus trifluoride product. The product yield was 95.6%, and the HLPC purity was 99.7%.

[0025] Example 2 Under nitrogen protection, phosphorus trichloride (2.74 kg, 20.0 mol) was added to the reactor, and then ionic liquid was slowly added (12.64 kg, 80.0 mol). After addition, the mixture was heated to 40 °C and stirred for 1 h. Phosphorus trifluoride gas was continuously generated during the reaction, and the phosphorus trifluoride gas was condensed and collected at -120 °C to obtain a liquid phosphorus trifluoride product. The product yield was 84.7%, and the HLPC purity was 99.5%.

[0026] Example 3 Under nitrogen protection, phosphorus trichloride (2.74 kg, 20.0 mol) was added to the reactor, and then ionic liquid was slowly added (1.24 kg, 80.0 mol). After addition, the mixture was heated to 40 °C and stirred for 1 h. Phosphorus trifluoride gas was continuously generated during the reaction, and the phosphorus trifluoride gas was condensed and collected at -120 °C to obtain a liquid phosphorus trifluoride product. The product yield was 86.3%, and the HLPC purity was 99.4%.

[0027] Example 4 Under nitrogen protection, phosphorus trichloride (2.74 kg, 20.0 mol) was added to the reactor, and then ionic liquid was slowly added (16.1 kg, 100.0 mol). After addition, the mixture was heated to 40 °C and stirred for reaction for 1 h. During the reaction process, phosphorus trifluoride gas was continuously generated and condensed and collected at -120 °C to obtain a liquid phosphorus trifluoride product. The product yield was 96.2% and the HLPC purity was 99.7%.

[0028] Example 5 Under nitrogen protection, phosphorus trichloride (2.74 kg, 20.0 mol) was added to the reactor, and then ionic liquid (12.64 kg, 80.0 mol) was slowly added. After addition, the mixture was heated to 50 °C and stirred for reaction for 30 min. During the reaction process, phosphorus trifluoride gas was continuously generated and condensed and collected at -120 °C to obtain a liquid phosphorus trifluoride product. The product yield was 83.2% and the HLPC purity was 99.4%.

[0029] Comparative Example 1 On the basis of Example 1, was replaced with sodium fluoride, and other operations and conditions were the same as those in Example 1: Under nitrogen protection, phosphorus trichloride (2.74 kg, 20.0 mol) was added to the reactor, and then sodium fluoride (3.36 kg, 80.0 mol) was slowly added. After addition, the mixture was heated to 40 °C and reacted for 1 h. During the reaction process, phosphorus trifluoride gas was continuously generated and condensed and collected at -120 °C to obtain a liquid phosphorus trifluoride product. The product yield was 61.7% and the HLPC purity was 91.3%.

[0030] Comparative Example 2 On the basis of Example 1, was replaced with ammonium fluoride, and other operations and conditions were the same as those in Example 1: Under nitrogen protection, phosphorus trichloride (2.74 kg, 20.0 mol) was added to the reactor, and then ammonium fluoride (2.96 kg, 80.0 mol) was slowly added. After addition, the mixture was heated to 40 °C and stirred for reaction for 1 h. During the reaction process, phosphorus trifluoride gas was continuously generated and condensed and collected at -120 °C to obtain a liquid phosphorus trifluoride product. The product yield was 69.5% and the HLPC purity was 84.8%.

[0031] Comparative Example 3 On the basis of Example 1, was replaced with tetrabutylammonium fluoride, and other operations and conditions were the same as those in Example 1: Under nitrogen protection, phosphorus trichloride (2.74 kg, 20.0 mol) was added to the reactor, and then tetrabutylammonium fluoride (20.88 kg, 80.0 mol) was slowly added. After the addition, the mixture was heated to 40 °C and stirred for 1 h. During the reaction, phosphorus trifluoride gas was continuously generated and condensed and collected at -120 °C to obtain a liquid product of phosphorus trifluoride. The product yield was 73.8% and the HLPC purity was 94.5%.

[0032] The above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. Thus, the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of phosphorus trifluoride, characterized in that, It includes the following steps: Under the protection of inert gas, react phosphorus trichloride with ionic liquid to obtain phosphorus trifluoride; The structural formula of the ionic liquid is: , or .

2. The preparation method according to claim 1, wherein The inert gas is selected from one or more of nitrogen, helium, neon and argon.

3. The preparation method according to claim 1, characterized in that, The reaction temperature is 30~50°C and the reaction time is 0.5~5 h.

4. The preparation method according to claim 1, wherein The molar ratio of phosphorus trichloride to ionic liquid is 1:(3~10).

5. The preparation method according to claim 1, wherein During the reaction process of this reaction method, phosphorus trifluoride gas is continuously generated, condensed and collected to obtain a liquid product of phosphorus trifluoride.

6. The preparation method according to claim 5, characterized in that, The temperature for condensation and collection is -140~-120°C.

7. The preparation method according to claim 1, characterized in that, It includes the following steps: Under nitrogen protection, phosphorus trichloride was added to the reactor, and then the ionic liquid was slowly added. After the addition was complete, the mixture was heated to 40 °C and stirred for 1 h. Phosphorus trifluoride gas was continuously generated during the reaction and was condensed and collected at -120 °C to obtain the liquid-phase product of phosphorus trifluoride.

8. The preparation method according to claim 1, wherein It includes the following steps: Under nitrogen protection, phosphorus trichloride was added to the reactor, and then the ionic liquid was slowly added . After the addition was complete, the mixture was heated to 40 °C and stirred for reaction for 1 h. During the reaction process, phosphorus trifluoride gas was continuously generated and condensed and collected at -120 °C to obtain a liquid-phase product of phosphorus trifluoride.

9. The preparation method according to claim 1, characterized in that, It includes the following steps: Under nitrogen protection, phosphorus trichloride is added to the reactor, and then the ionic liquid is slowly added . After the addition is complete, the mixture is heated to 40 °C and stirred for reaction for 1 h. During the reaction process, phosphorus trifluoride gas is continuously generated and condensed and collected at -120 °C to obtain a liquid-phase product of phosphorus trifluoride.

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