A method for preparing phosphorus trifluoride

Abstract

The present invention provides a method for preparing phosphorus trifluoride, comprising the steps of mixing a phosphorus triiodide organic solution with a metal fluoride salt, and reacting until no bubbles are generated to obtain phosphorus trifluoride; the metal fluoride salt comprises any one of sodium fluoride, potassium fluoride, or aluminum fluoride, or a combination of at least two. The method is simple to operate and, by selecting a suitable metal fluoride salt, produces a phosphorus trifluoride product with stable quality, high purity, and low impurities, making it suitable for industrial production of high-purity phosphorus trifluoride.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis and relates to a method for preparing fluoride, in particular to a method for preparing phosphorus trifluoride. Background Art

[0002] Phosphorus trifluoride is an inorganic compound with the chemical formula PF3. It is a colorless, odorless, toxic gas at room temperature and pressure. In liquid form, it is a colorless, transparent liquid that emits little smoke in air and is quite stable. When heated, it reacts with hydrogen to form PH3 and reacts with water to form phosphorous acid and hydrogen fluoride. Furthermore, phosphorus trifluoride decomposes in alkali and is soluble in ethanol.

[0003] Currently, there are few public disclosures about phosphorus trifluoride production processes. CN101955173A discloses a technical solution for preparing phosphorus trifluoride by reacting phosphorus trichloride and zinc fluoride. The process comprises: an integrated reactor connected to a hydrogen fluoride storage bottle via a connecting pipeline, a dropping funnel and a conduit connected to the top of the reactor, the dropping funnel and conduit connected to a dryer via a connecting pipeline, and the dryer connected to a zinc fluoride inlet pipe, all assembled into one.

[0004] However, the reaction activity of this technical solution is low, and the reaction between phosphorus trichloride and zinc fluoride is more likely to form by-product phosphorus fluoride, making it difficult to remove impurities and difficult to obtain high-purity phosphorus trifluoride.

[0005] CN105776168A discloses a method for preparing hexafluorophosphate. The method involves slowly adding phosphorus trichloride and anhydrous hydrogen fluoride to a gas-liquid mixer in a proportional amount, wherein the anhydrous hydrogen fluoride is in excess relative to the phosphorus trichloride. The mixture reacts at 50-60°C to produce phosphorus trifluoride and hydrogen chloride. This process requires the use of hydrogen fluoride gas, which has the disadvantages of severe equipment corrosion and low reaction conversion rates.

[0006] Therefore, in view of the shortcomings of the existing technology, it is necessary to provide a method for preparing phosphorus trifluoride with a simple production process, cheap and readily available raw materials, high reaction conversion rate, few gaseous by-products and low corrosion to equipment. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing phosphorus trifluoride, which can obtain phosphorus trifluoride with high purity and high yield, has low production cost, and is suitable for industrial production of high-purity phosphorus trifluoride products.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing phosphorus trifluoride, comprising the following steps:

[0010] Mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting until no bubbles are generated to obtain phosphorus trifluoride;

[0011] The metal fluoride salt includes any one of sodium fluoride, potassium fluoride or aluminum fluoride, or a combination of at least two of them. Typical but non-limiting combinations include a combination of sodium fluoride and potassium fluoride, a combination of sodium fluoride and aluminum fluoride, a combination of potassium fluoride and aluminum fluoride, or a combination of sodium fluoride, potassium fluoride and aluminum fluoride.

[0012] The preparation method provided by the present invention avoids the problem of generating phosphorus trichloride byproducts during the reaction of phosphorus trichloride and zinc fluoride by selecting a specific fluoride metal salt, and can obtain a phosphorus trifluoride product with high purity, stable quality and less impurities. Moreover, the obtained phosphorus trifluoride has a high yield, and the preparation method has prospects for industrial application.

[0013] As a preferred technical solution, the reaction of the phosphorus triiodide organic solution and the metal fluoride salt is carried out in a rotary evaporator. The reaction is carried out by rotary evaporation, which improves the mass transfer effect of the reaction system, facilitates the reaction, collects the product, and separates the solvent from the solid by-product.

[0014] Preferably, the organic solvent used in the phosphorus triiodide organic solution is carbon disulfide.

[0015] Preferably, the concentration of the organic solution of phosphorus triiodide is 1-5 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] Preferably, the molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:(3-6), for example, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5 or 1:6, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] Preferably, the method for preparing phosphorus triiodide in the phosphorus triiodide organic solution comprises the following steps:

[0018] A phosphorus source and iodine are mixed, and a temperature-controlled reaction is carried out under a protective atmosphere. Then, excess iodine is removed by sublimation to obtain the phosphorus triiodide.

[0019] The protective atmosphere includes nitrogen and / or inert gas.

[0020] The inert gas includes any one of helium, neon or argon, or a combination of at least two of them. Typical but non-limiting combinations include a combination of helium and neon, a combination of neon and argon, a combination of helium and argon, or a combination of helium, neon and argon.

[0021] Illustratively, the phosphorus source is a dried phosphorus source, and the phosphorus triiodide obtained by the method for preparing phosphorus triiodide of the present invention has high purity, which is conducive to the subsequent acquisition of high-purity phosphorus trifluoride.

[0022] Preferably, the phosphorus source includes white phosphorus and / or red phosphorus.

[0023] Preferably, the molar ratio of the phosphorus source to the iodine element is 2:(3.5-6), for example, 2:3.5, 2:4, 2:4.5, 2:5, 2:5.5 or 2:6, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, the temperature-controlled reaction includes a first reaction and a second reaction performed sequentially;

[0025] The first reaction is carried out at a temperature of 330-400° C. for 10-20 minutes;

[0026] The second reaction is carried out at a temperature of 270-290° C. for 10-20 minutes.

[0027] The preparation method provided by the present invention comprises a first reaction and a second reaction which are carried out in sequence through a temperature-controlled reaction. During the first reaction, most of the phosphorus triiodide is synthesized. During the second reaction, the reaction between iodine and the remaining phosphorus is promoted. The generated phosphorus triiodide is not easily decomposed, thereby improving the conversion rate.

[0028] The temperature of the first reaction of the present invention is 330-400°C, for example, 330°C, 340°C, 350°C, 360°C, 380°C or 400°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] The time of the first reaction of the present invention is 10-20 minutes, for example, it can be 10 minutes, 12 minutes, 15 minutes, 16 minutes, 18 minutes or 20 minutes, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0030] The temperature of the second reaction of the present invention is 270-290°C, for example, it can be 270°C, 275°C, 280°C, 285°C or 290°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0031] The time of the second reaction of the present invention is 10-20 minutes, for example, it can be 10 minutes, 12 minutes, 15 minutes, 16 minutes, 18 minutes or 20 minutes, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the preparation method further comprises a recovery step after the reaction is continued until no bubbles are generated:

[0033] The residual liquid from the reaction was rotary evaporated to separate the organic solvent and the iodine metal salt.

[0034] Preferably, after the iodine metal salt is dissolved, it reacts with an oxidant to obtain elemental iodine, and the elemental iodine is recovered after extraction.

[0035] Preferably, the oxidizing agent comprises chlorine gas.

[0036] Preferably, the extraction is performed using carbon tetrachloride.

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

[0038] (1) mixing a phosphorus source and an iodine element, performing a temperature-controlled reaction under a protective atmosphere, and then removing excess iodine element by sublimation to obtain the phosphorus triiodide; dissolving the phosphorus triiodide in an organic solvent, carbon disulfide, to obtain a phosphorus triiodide organic solution with a concentration of 1-5 mol / L;

[0039] The phosphorus source includes white phosphorus and / or red phosphorus;

[0040] The molar ratio of the phosphorus source to the iodine element is 2:(3.5-6);

[0041] The temperature-controlled reaction includes a first reaction and a second reaction performed sequentially, wherein the first reaction is performed at a temperature of 330-400° C. for 10-20 minutes, and the second reaction is performed at a temperature of 270-290° C. for 10-20 minutes;

[0042] (2) mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting them in a rotary evaporator until no bubbles are generated to obtain phosphorus trifluoride and a reaction residue;

[0043] The metal fluoride salt includes any one of sodium fluoride, potassium fluoride or aluminum fluoride or a combination of at least two thereof;

[0044] The phosphorus triiodide organic solution is a combination of ethanol and acetone in a volume ratio of 1: (0.8-1.2);

[0045] The molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:(3-6);

[0046] (3) rotary evaporating the residual liquid to separate the organic solvent and the iodine metal salt; after the iodine metal salt is dissolved, reacting with chlorine to obtain elemental iodine, and recovering the elemental iodine after extraction with carbon tetrachloride.

[0047] The numerical range described in the present 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 simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The preparation method provided by the present invention has a wide range of raw material sources and low cost; furthermore, by not using phosphorus trichloride, the generation of difficult-to-separate phosphorus chlorochloride by-products is reduced; furthermore, the reaction process has low corrosion to reaction equipment, and a phosphorus trifluoride product with high purity, stable quality and less impurities can be obtained; moreover, the obtained phosphorus trifluoride has a high yield, and the preparation method has industrial application prospects. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0051] Example 1

[0052] This embodiment provides a method for preparing phosphorus trifluoride, which comprises the following steps:

[0053] (1) mixing a phosphorus source and an iodine element, performing a temperature-controlled reaction under a nitrogen atmosphere, and then removing excess iodine element by sublimation to obtain the phosphorus triiodide; dissolving the phosphorus triiodide in an organic solvent, carbon disulfide, to obtain a phosphorus triiodide organic solution with a concentration of 2 mol / L;

[0054] The phosphorus source is commercially available white phosphorus;

[0055] The molar ratio of the phosphorus source to the iodine element is 2:4;

[0056] The temperature-controlled reaction includes a first reaction and a second reaction performed sequentially, wherein the first reaction is performed at a temperature of 360° C. for 15 minutes, and the second reaction is performed at a temperature of 280° C. for 15 minutes;

[0057] (2) mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting them in a rotary evaporator until no bubbles are generated to obtain phosphorus trifluoride and a reaction residue;

[0058] The metal fluoride salt is sodium fluoride;

[0059] The molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:4;

[0060] (3) rotary evaporation of the residual liquid to separate the organic solvent and the iodine metal salt; the iodine metal salt is dissolved in water, reacted with chlorine to obtain elemental iodine, and the elemental iodine is recovered after extraction with carbon tetrachloride.

[0061] Example 2

[0062] This embodiment provides a method for preparing phosphorus trifluoride, which comprises the following steps:

[0063] (1) mixing a phosphorus source and an iodine element, performing a temperature-controlled reaction under a nitrogen atmosphere, and then removing excess iodine element by sublimation to obtain the phosphorus triiodide; dissolving the phosphorus triiodide in an organic solvent, carbon disulfide, to obtain a phosphorus triiodide organic solution with a concentration of 1 mol / L;

[0064] The phosphorus source is commercially available white phosphorus;

[0065] The molar ratio of the phosphorus source to the iodine element is 2:3.5;

[0066] The temperature-controlled reaction includes a first reaction and a second reaction performed sequentially, wherein the first reaction is performed at a temperature of 330° C. for 20 minutes, and the second reaction is performed at a temperature of 270° C. for 20 minutes;

[0067] (2) mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting them in a rotary evaporator until no bubbles are generated to obtain phosphorus trifluoride and a reaction residue;

[0068] The metal fluoride salt is sodium fluoride;

[0069] The molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:3;

[0070] (3) rotary evaporation of the residual liquid to separate the organic solvent and the iodine metal salt; the iodine metal salt is dissolved in water, reacted with chlorine to obtain elemental iodine, and the elemental iodine is recovered after extraction with carbon tetrachloride.

[0071] Example 3

[0072] This embodiment provides a method for preparing phosphorus trifluoride, which comprises the following steps:

[0073] (1) mixing a phosphorus source and an iodine element, performing a temperature-controlled reaction under a nitrogen atmosphere, and then removing excess iodine element by sublimation to obtain the phosphorus triiodide; dissolving the phosphorus triiodide in an organic solvent, carbon disulfide, to obtain a phosphorus triiodide organic solution with a concentration of 5 mol / L;

[0074] The phosphorus source is commercially available white phosphorus;

[0075] The molar ratio of the phosphorus source to the iodine element is 2:6;

[0076] The temperature-controlled reaction includes a first reaction and a second reaction performed sequentially, wherein the first reaction is performed at a temperature of 400° C. for 10 minutes, and the second reaction is performed at a temperature of 290° C. for 10 minutes;

[0077] (2) mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting them in a rotary evaporator until no bubbles are generated to obtain phosphorus trifluoride and a reaction residue;

[0078] The metal fluoride salt is sodium fluoride;

[0079] The molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:6;

[0080] (3) rotary evaporation of the residual liquid to separate the organic solvent and the iodine metal salt; the iodine metal salt is dissolved in water, reacted with chlorine to obtain elemental iodine, and the elemental iodine is recovered after extraction with carbon tetrachloride.

[0081] Example 4

[0082] This embodiment provides a method for preparing phosphorus trifluoride, which is the same as that of Example 1 except that the phosphorus source in step (1) is replaced by commercial red phosphorus in an equimolar amount from commercially available white phosphorus.

[0083] Example 5

[0084] This embodiment provides a method for preparing phosphorus trifluoride, which is the same as that of Example 1 except that the metal fluoride salt in step (2) is potassium fluoride and the molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:4.

[0085] Example 6

[0086] This embodiment provides a method for preparing phosphorus trifluoride, which is the same as that of Example 1 except that the metal fluoride salt in step (2) is aluminum fluoride and the molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:4.

[0087] Example 7

[0088] This embodiment provides a method for preparing phosphorus trifluoride, which comprises the following steps:

[0089] (1) mixing a phosphorus source and an iodine element, performing a temperature-controlled reaction under a nitrogen atmosphere, and then removing excess iodine element by sublimation to obtain the phosphorus triiodide; dissolving the phosphorus triiodide in an organic solvent, carbon disulfide, to obtain a phosphorus triiodide organic solution with a concentration of 2 mol / L;

[0090] The phosphorus source is commercially available white phosphorus;

[0091] The molar ratio of the phosphorus source to the iodine element is 2:4;

[0092] The temperature-controlled reaction is carried out at a temperature of 360° C. for 30 minutes;

[0093] (2) mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting them in a rotary evaporator until no bubbles are generated to obtain phosphorus trifluoride and a reaction residue;

[0094] The metal fluoride salt is sodium fluoride;

[0095] The molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:4;

[0096] (3) rotary evaporation of the residual liquid to separate the organic solvent and the iodine metal salt; the iodine metal salt is dissolved in water, reacted with chlorine to obtain elemental iodine, and the elemental iodine is recovered after extraction with carbon tetrachloride.

[0097] Example 8

[0098] This embodiment provides a method for preparing phosphorus trifluoride, which comprises the following steps:

[0099] (1) mixing a phosphorus source and an iodine element, performing a temperature-controlled reaction under a nitrogen atmosphere, and then removing excess iodine element by sublimation to obtain the phosphorus triiodide; dissolving the phosphorus triiodide in an organic solvent, carbon disulfide, to obtain a phosphorus triiodide organic solution with a concentration of 2 mol / L;

[0100] The phosphorus source is commercially available white phosphorus;

[0101] The molar ratio of the phosphorus source to the iodine element is 2:4;

[0102] The temperature-controlled reaction is carried out at a temperature of 280° C. for 30 minutes;

[0103] (2) mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting them in a rotary evaporator until no bubbles are generated to obtain phosphorus trifluoride and a reaction residue;

[0104] The metal fluoride salt is sodium fluoride;

[0105] The molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:4;

[0106] (3) rotary evaporation of the residual liquid to separate the organic solvent and the iodine metal salt; the iodine metal salt is dissolved in water, reacted with chlorine to obtain elemental iodine, and the elemental iodine is recovered after extraction with carbon tetrachloride.

[0107] Comparative Example 1

[0108] This comparative example provides a method for preparing phosphorus trifluoride, which is the same as Example 1 except that the metal fluoride salt in step (2) is zinc fluoride and the molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:4.

[0109] The phosphorus trifluoride obtained in Examples 1-8 and Comparative Example 1 was purified by conventional distillation; the purity and yield of the obtained phosphorus trifluoride are shown in Table 1, wherein the purity was measured by gas chromatography and the yield was calculated based on the phosphorus source.

[0110] Table 1

[0111]

[0112]

[0113] In summary, the preparation method provided by the present invention has a wide range of raw material sources and low cost. Moreover, by selecting a suitable metal fluoride salt, the production of difficult-to-separate phosphorus trifluoride by-products is reduced. Moreover, the reaction process is less corrosive to the reaction equipment, and a phosphorus trifluoride product with high purity, stable quality and less impurities can be obtained. Moreover, the obtained phosphorus trifluoride has a high yield, and the preparation method has prospects for industrial application.

[0114] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing phosphorus trifluoride, characterized in that: The preparation method comprises the following steps: Mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting until no bubbles are generated to obtain phosphorus trifluoride; The metal fluoride salt includes any one of sodium fluoride, potassium fluoride or aluminum fluoride or a combination of at least two thereof; The phosphorus triiodide in the phosphorus triiodide organic solution is prepared by the following method: Mixing a phosphorus source and an iodine element, performing a temperature-controlled reaction under a protective atmosphere, and then removing excess iodine element by sublimation to obtain the phosphorus triiodide; The temperature-controlled reaction includes a first reaction and a second reaction performed sequentially; The first reaction is carried out at a temperature of 330-400° C. for 10-20 minutes; The second reaction is carried out at a temperature of 270-290° C. for 10-20 minutes.

2. The preparation method according to claim 1, characterized in that The organic solvent used in the phosphorus triiodide organic solution includes carbon disulfide.

3. The preparation method according to claim 1 or 2, characterized in that The concentration of the phosphorus triiodide organic solution is 1-5 mol / L.

4. The preparation method according to claim 1, characterized in that The molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:(3-6).

5. The preparation method according to claim 1, characterized in that The phosphorus source includes white phosphorus and / or red phosphorus.

6. The preparation method according to claim 1, characterized in that The molar ratio of the phosphorus source to the iodine element is 2:(3.5-6).

7. The preparation method according to claim 1, characterized in that The preparation method further comprises a recovery step after the reaction is continued until no bubbles are generated: The residual liquid from the reaction was rotary evaporated to separate the organic solvent and the iodine metal salt.

8. The preparation method according to claim 7, characterized in that After the iodine metal salt is dissolved, it reacts with an oxidant to obtain elemental iodine, which is then extracted and recovered.

9. The preparation method according to claim 8, characterized in that The oxidizing agent includes chlorine gas.

10. The preparation method according to claim 8, characterized in that The extraction is performed using carbon tetrachloride.

11. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: (1) mixing a phosphorus source and an iodine element, performing a temperature-controlled reaction under a protective atmosphere, and then removing excess iodine element by sublimation to obtain the phosphorus triiodide; dissolving the phosphorus triiodide in an organic solvent, carbon disulfide, to obtain a phosphorus triiodide organic solution with a concentration of 1-5 mol / L; The phosphorus source includes white phosphorus and / or red phosphorus; The molar ratio of the phosphorus source to the iodine element is 2:(3.5-6); The temperature-controlled reaction includes a first reaction and a second reaction performed sequentially, wherein the first reaction is performed at a temperature of 330-400° C. for 10-20 minutes, and the second reaction is performed at a temperature of 270-290° C. for 10-20 minutes; (2) mixing the phosphorus triiodide organic solution and the metal fluoride salt, and reacting them in a rotary evaporator until no bubbles are generated to obtain phosphorus trifluoride and a reaction residue; The metal fluoride salt includes any one of sodium fluoride, potassium fluoride or aluminum fluoride or a combination of at least two thereof; The molar ratio of phosphorus in the phosphorus triiodide organic solution to fluorine in the metal fluoride salt is 1:(3-6); (3) rotary evaporating the residual liquid to separate the organic solvent and the iodine metal salt; after the iodine metal salt is dissolved, reacting with chlorine to obtain elemental iodine, and recovering the elemental iodine after extraction with carbon tetrachloride.

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