A process for the preparation of phosphorus trifluoride

Abstract

The application relates to a preparation method of phosphorus trifluoride, in particular to the chemical synthesis technical field, and the preparation method comprises the following steps: reacting phosphorus trichloride and ammonium fluoride with a molar ratio of 1:(3-5) under a protective atmosphere to obtain phosphorus trifluoride. The preparation method provided by the application can obtain phosphorus trifluoride with high purity and high yield by reasonably designing the preparation process of phosphorus trifluoride, and the production cost is low, the production safety risk is low, and the method is suitable for industrial production of high-purity phosphorus trifluoride products.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, specifically to a method for preparing phosphorus trifluoride. Background Technology

[0002] Currently, phosphorus trifluoride is an inorganic compound 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 polymer materials, phosphorus trifluoride can be used as a reactant to synthesize fluorinated organic dithiophosphates, terephthalates, and other polymers with excellent corrosion-resistant properties. In organic synthesis, phosphorus trifluoride plays an important role as a reactant in the formation of fluorinated hydrocarbons, the fluorination of aromatic compounds, and the reactions of amines with acid anhydrides.

[0003] Currently, there is limited public information available about the production process of phosphorus trifluoride.

[0004] CN101955173A discloses a technology for preparing phosphorus trifluoride by reacting phosphorus trichloride and zinc fluoride. The technology mainly consists of a reactor that is integrally constructed and connected to a hydrogen fluoride storage bottle via connecting pipelines. A dropping funnel and a conduit are connected to the top of the reactor, and the dropping funnel and conduit are connected to a dryer via connecting pipelines. The dryer is connected to a zinc fluoride inlet pipe. This integrated assembly method, which uses the reaction of phosphorus trichloride and zinc fluoride to prepare phosphorus trifluoride, easily forms the byproduct phosphorus fluorochloride, making impurity removal difficult and resulting in low-purity phosphorus trifluoride.

[0005] The scheme disclosed in CN117163925A obtains phosphorus trifluoride by mixing an organic solution of phosphorus triiodide with a fluorinated metal salt and reacting until no more bubbles are generated. Although this scheme has a very good conversion efficiency, it has drawbacks such as the complex preparation process of phosphorus triiodide and the difficulty in obtaining and expensive raw materials.

[0006] Therefore, in view of the shortcomings of the existing technology, there is a need to provide a method for preparing phosphorus trifluoride that is simple in production process, has cheap and readily available raw materials, high reaction conversion rate, few gaseous by-products and low corrosivity to equipment, and can reduce production safety risks. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing phosphorus trifluoride, so as to solve the problems of low product purity and low reactant conversion rate in the preparation of phosphorus trifluoride.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This invention provides a method for preparing phosphorus trifluoride, the method comprising:

[0010] Phosphorus trichloride and ammonium fluoride in a molar ratio of 1:(3-5) were reacted under a protective atmosphere to obtain phosphorus trifluoride.

[0011] The preparation method provided by this invention, through the rational design of the preparation process of phosphorus trifluoride, can obtain phosphorus trifluoride with high purity and high yield, and has lower production cost and lower production safety risk, and is suitable for industrial production of high-purity phosphorus trifluoride products.

[0012] As a preferred embodiment of the present invention, the protective atmosphere includes one or a combination of at least two of nitrogen, helium, neon, or argon.

[0013] As a preferred embodiment of the present invention, the reaction is carried out in a device equipped with stirring and reflux condensation.

[0014] As a preferred embodiment of the present invention, the reaction is carried out in an alcohol solution system.

[0015] As a preferred embodiment of the present invention, the reaction is to add phosphorus trichloride dropwise to ammonium fluoride material.

[0016] As a preferred embodiment of the present invention, the dropping rate of phosphorus trichloride in the reaction is 0.55-0.75 g / min.

[0017] As a preferred embodiment of the present invention, the reaction temperature is 10-40℃.

[0018] As a preferred embodiment of the present invention, the reaction is completed by keeping the temperature for 10-15 minutes after the addition of phosphorus trichloride.

[0019] As a preferred technical solution of the present invention, the gaseous material obtained from the reaction is purified into phosphorus trifluoride by condensation and gas washing.

[0020] As a preferred embodiment of the present invention, the condensation temperature is 0-10℃.

[0021] Preferably, the medium used for gas washing includes concentrated acid.

[0022] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0023] (1) The preparation method of phosphorus trifluoride provided by this invention involves raw materials that are inexpensive, widely available, require minimal equipment, and are not highly corrosive. The synthesis steps are simple, and phosphorus trifluoride products with high purity, stable quality, and few metallic impurities can be obtained through simple purification. This preparation method has promising prospects for industrial application, with a phosphorus trifluoride product yield ≥78% and a purity ≥89%.

[0024] (2) This invention features a mild reaction temperature, high reaction efficiency, and easy separation of products and raw materials. Compared with CN101955173A and CN117228643A, this technical solution can react at room temperature, the reaction conditions are easy to control, and the requirements for equipment design are low. Compared with patent CN117163925A, although the yield of this technical solution is not as high as that of iodine reagent, the raw materials are readily available and inexpensive, the process is relatively simple, and it has better economic benefits. Detailed Implementation

[0025] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0026] This embodiment provides a method for preparing phosphorus trifluoride, the method comprising:

[0027] Phosphorus trichloride and ammonium fluoride in a molar ratio of 1:(3-5) were reacted under a protective atmosphere to obtain phosphorus trifluoride.

[0028] In this invention, the molar ratio of phosphorus trichloride to ammonium fluoride is controlled to be 1:(3-5), for example, it can be 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4, 1:4.2, 1:4.4, 1:4.6, 1:4.8 or 1:5, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0029] The protective atmosphere includes one or a combination of at least two of nitrogen, helium, neon, or argon.

[0030] For example, the combination of protective atmospheres can be selected as a combination of nitrogen and helium, a combination of helium and neon, a combination of neon and argon, a combination of nitrogen and argon, etc.

[0031] The reaction is carried out in a stirred apparatus with reflux condensation.

[0032] The reaction is carried out in an alcohol solution system.

[0033] In this invention, the alcohol solution system used in the reaction includes one or a combination of at least two commonly used alcohols in the art, such as methanol, ethanol, and glycerol.

[0034] In this invention, the mass-to-volume ratio of ammonium fluoride to alcohol (g / mL) is (10-18):100, for example, it can be 10:100, 10.5:100, 11:100, 11.5:100, 12:100, 12.5:100, 13:100, 13.5:100, 14:100, 14.5:100, 15:100, 15.5:100, 16:100, 16.5:100, 17:100, 17.5:100, or 18:100, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0035] The reaction involves adding phosphorus trichloride dropwise to ammonium fluoride.

[0036] The dropping rate of phosphorus trichloride in the reaction is 0.55-0.75 g / min, for example, it can be 0.55 g / min, 0.56 g / min, 0.58 g / min, 0.6 g / min, 0.62 g / min, 0.64 g / min, 0.66 g / min, 0.68 g / min, 0.7 g / min, 0.72 g / min, 0.74 g / min or 0.75 g / min, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0037] The reaction temperature is 10-40℃, for example, it can be 10℃, 12℃, 14℃, 16℃, 18℃, 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃ or 40℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0038] The reaction is terminated after phosphorus trichloride is added dropwise and kept at a constant temperature for 10-15 minutes. For example, it can be 10 minutes, 10.5 minutes, 11 minutes, 11.5 minutes, 12 minutes, 12.5 minutes, 13 minutes, 13.5 minutes, 14 minutes, 14.5 minutes, or 15 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0039] The gaseous material obtained from the reaction is purified into phosphorus trifluoride through condensation and gas washing.

[0040] The condensation temperature is 0-10℃, for example, it can be 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, 9℃ or 10℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0041] The medium used for gas washing includes concentrated acid.

[0042] In this invention, the medium used in the gas washing process is concentrated acid such as concentrated sulfuric acid, which does not affect the product indicators of phosphorus trifluoride.

[0043] Furthermore, to illustrate that the product obtained by the preparation method provided by the present invention has good purity and reaction raw material conversion rate, a practical example is used for explanation, as follows:

[0044] Example 1

[0045] This embodiment provides a method for preparing phosphorus trifluoride, the method comprising the following steps:

[0046] The reactor was protected by purging with an inert gas (nitrogen). Approximately 100 mL of anhydrous ethanol (containing less than 150 ppm of water) was added, followed by 14.8 g of ammonium fluoride. The mixture was stirred, and then 13.7 g of phosphorus trichloride was slowly added dropwise (at a rate of 0.65 g / min). The molar ratio of phosphorus trichloride to ammonium fluoride was 1:4. The addition was completed within 20 min. The reaction temperature was controlled at 25 °C, and the reflux temperature was controlled at 5 °C to obtain phosphorus trifluoride. The total reaction time was 30 min.

[0047] The gas generated in the reaction is first refluxed by condensation to allow phosphorus trichloride to reflux, and then washed with concentrated sulfuric acid to remove any impurities such as hydrogen fluoride and hydrogen chloride that may be generated. The remaining gas obtained is phosphorus trifluoride.

[0048] Calculations showed that the yield of phosphorus trifluoride was 92.05% and the purity was 91%.

[0049] Example 2

[0050] This embodiment provides a method for preparing phosphorus trifluoride, the method comprising the following steps:

[0051] The reactor was protected by purging with an inert gas (helium). About 100 mL of anhydrous ethanol (water content less than 150 ppm) was added, followed by 11.1 g of ammonium fluoride. The mixture was stirred, and then 13.7 g of phosphorus trichloride was slowly added dropwise (dropping rate 0.55 g / min). The molar ratio of phosphorus trichloride to ammonium fluoride was 1:3. The addition was completed within 20 min. The reaction temperature was controlled at about 25 °C, and the reflux temperature was controlled at 0 °C to obtain phosphorus trifluoride. The total reaction time was 30 min.

[0052] The gas generated in the reaction is first refluxed by condensation to allow phosphorus trichloride to reflux, and then washed with concentrated sulfuric acid to remove any impurities such as hydrogen fluoride and hydrogen chloride that may be generated. The remaining gas obtained is phosphorus trifluoride.

[0053] Calculations showed that the yield of phosphorus trifluoride was 90.91% and the purity was 89%.

[0054] Example 3

[0055] This embodiment provides a method for preparing phosphorus trifluoride, the method comprising the following steps:

[0056] The reactor was protected by purging with an inert gas (argon). About 100 mL of anhydrous ethanol (water content less than 150 ppm) was added, followed by 18.5 g of ammonium fluoride. The mixture was stirred, and then 13.7 g of phosphorus trichloride was slowly added dropwise (dropping rate 0.75 g / min). The molar ratio of phosphorus trichloride to ammonium fluoride was 1:5. The addition was completed within 20 min. The reaction temperature was controlled at 25 °C, and the reflux temperature was controlled at 10 °C to obtain phosphorus trifluoride. The total reaction time was 30 min.

[0057] The gas generated in the reaction is first refluxed by condensation to allow phosphorus trichloride to reflux, and then washed with concentrated sulfuric acid to remove any impurities such as hydrogen fluoride and hydrogen chloride that may be generated. The remaining gas obtained is phosphorus trifluoride.

[0058] Calculations showed that the yield of phosphorus trifluoride was 91.48% and the purity was 89%.

[0059] Example 4

[0060] The only difference from Example 1 is that the reaction temperature in step (1) is controlled at 10°C in this example.

[0061] The gas generated in the reaction is first refluxed by condensation to allow phosphorus trichloride to reflux, and then washed with concentrated sulfuric acid to remove any impurities such as hydrogen fluoride and hydrogen chloride that may be generated. The remaining gas obtained is phosphorus trifluoride.

[0062] Calculations showed that the yield of phosphorus trifluoride was 90.91% and the purity was 91%.

[0063] Example 5

[0064] The only difference from Example 1 is that the reaction temperature in step (1) is controlled at 40°C in this example.

[0065] The gas generated in the reaction is first refluxed by condensation to allow phosphorus trichloride to reflux, and then washed with concentrated sulfuric acid to remove any impurities such as hydrogen fluoride and hydrogen chloride that may be generated. The remaining gas obtained is phosphorus trifluoride.

[0066] Calculations showed that the yield of phosphorus trifluoride was 89.77% and the purity was 89%.

[0067] Comparative Example 1

[0068] The only difference from Example 1 is that the molar ratio of phosphorus trichloride to ammonium fluoride is 1:6.

[0069] Comparative Example 2

[0070] The only difference from Example 1 is that phosphorus trichloride is replaced with an equal amount of phosphorus triiodide.

[0071] Comparative Example 3

[0072] The only difference from Example 1 is that ammonium fluoride is replaced with an equal amount of sodium fluoride.

[0073] Comparative Example 4

[0074] The only difference from Example 1 is that ammonium fluoride is replaced with an equal amount of zinc fluoride.

[0075] Comparative Example 5

[0076] The only difference from Example 1 is that ethanol is replaced with an equal amount of carbon disulfide.

[0077] Comparative Example 6

[0078] The only difference from Example 1 is that phosphorus trichloride and ammonium fluoride are directly mixed and reacted.

[0079] Comparative Example 7

[0080] The only difference from Example 1 is that the dropping rate of phosphorus trichloride is 1 g / min.

[0081] The phosphorus trifluoride obtained in the examples and comparative examples was weighed; the purity and yield of the obtained phosphorus trifluoride are shown in Table 1, wherein the purity was measured by gas chromatography-mass spectrometry and the yield was calculated based on the phosphorus source.

[0082] Table 1

[0083]

[0084] Referring to Table 1, comparing Example 1 and Comparative Example 1, it can be seen that increasing the proportion of ammonium fluoride decreases both purity and yield; comparing Example 1 and Comparative Example 2, it can be seen that using phosphorus triiodide results in a relatively vigorous reaction, producing hydrogen, ammonia, and elemental iodine, which hinders the effective progress of the reaction; comparing Example 1, Comparative Example 3, and Comparative Example 4, it can be seen that sodium fluoride and zinc fluoride are not sufficiently reactive and require a higher temperature for reaction; comparing Example 1 and Comparative Example 5, it can be seen that carbon disulfide is not as effective as ethanol as a solvent; comparing Example 1 and Comparative Example 6, it can be seen that the reaction is incomplete without a solvent; comparing Example 1 and Comparative Example 7, it can be seen that increasing the titration rate slightly decreases both the purity and yield of the product.

[0085] In this scheme, the price of PCl3 is approximately 3 yuan / kg, and the price of ammonium fluoride is approximately 5 yuan / kg. Based on the phosphorus source, with a yield of 83%, the cost of producing 1 kg of PF3 is 13.24 yuan / kg. Comparing this to the existing technology CN117163925A, which has a similar conversion rate of 86%, the cost of producing 1 kg of PF3 is 1638.64 yuan / kg because PCl3 is approximately 300 yuan / kg and sodium fluoride is approximately 4 yuan / kg. Therefore, the scheme provided by this invention significantly reduces production costs and has a considerable advantage.

[0086] In summary, the raw materials used in the preparation method provided by this invention are widely available, have low cost, and possess considerable purity and conversion rate. The process equipment is simple, which is conducive to large-scale production.

[0087] The present invention is described in detail through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0088] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0089] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0090] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing phosphorus trifluoride, characterized in that, The preparation method includes: Phosphorus trichloride and ammonium fluoride in a molar ratio of 1:(3-5) are reacted under a protective atmosphere to obtain phosphorus trifluoride; the reaction temperature is 10-38℃; the reaction is carried out in an alcohol solution system; the reaction is a dropwise addition reaction of phosphorus trichloride to ammonium fluoride; the dropping rate of phosphorus trichloride in the reaction is 0.55-0.75 g / min.

2. The preparation method according to claim 1, characterized in that, The protective atmosphere includes one or a combination of at least two of nitrogen, helium, neon, or argon.

3. The preparation method according to claim 1 or 2, characterized in that, The reaction is carried out in a stirred apparatus with reflux condensation.

4. The preparation method according to claim 1, characterized in that, The reaction was completed by keeping the temperature at 10-15 minutes after the addition of phosphorus trichloride.

5. The preparation method according to claim 1, characterized in that, The gaseous material obtained from the reaction is purified into phosphorus trifluoride through condensation and gas washing.

6. The preparation method according to claim 5, characterized in that, The condensation temperature is 0-10℃.

7. The preparation method according to claim 5, characterized in that, The medium used for gas washing includes concentrated acid.

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