An Electrochemical Preparation Method of Tris(1,1,1,3,3,3-Hexafluoro-2-propyl) Phosphite

Abstract

The present invention discloses an electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite, belonging to the technical field of electrolysis processes for producing compounds. The present invention includes the following steps: white phosphorus, hexafluoroisopropanol are mixed with an activating additive, an organic base, an electrolyte, and an organic solvent to form an electrolytic reaction solution; the electrolytic reaction solution is electrolyzed under the action of direct current, white phosphorus is oxidized at the anode and then nucleophilically attacked by hexafluoroisopropanol to generate tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite, and hydrogen atoms are reduced at the cathode to form hydrogen gas. The present invention has the advantages of being simple and fast, having high safety, few by-products with high utilization value, and low cost; this method has a high atomic utilization rate, weak corrosiveness to the device, meets the requirements of green and safe production, and has good industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolysis processes for producing compounds, and in particular to an electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite. Background Art

[0002] Trivalent organophosphorus compounds are an important class of organic compounds that have a wide range of applications in multiple fields. These compounds typically have three organic groups attached to a phosphorus atom, forming a sp 3 hybridized trigonal pyramid configuration. Due to the unique electronic structure of the phosphorus atom, trivalent organophosphorus compounds exhibit rich chemical properties, including electrophilicity, amphiphilicity, and dienophilic reaction characteristics. These properties enable trivalent organophosphorus compounds to participate in various organic reactions as effective ligands or catalysts. Based on these characteristics, trivalent organophosphorus compounds are an extremely important bulk chemical product, widely used in flame retardants, ligands, plasticizers, etc., and are also used in the synthesis of pesticides, dyes, pharmaceuticals, and other organic chemical products.

[0003] Existing methods for synthesizing trivalent organophosphorus compounds, such as those provided in the literature (Donath, M., Schwedtmann, K., Schneider, T. et al. Direct conversion of white phosphorus to versatile phosphorus transfer reagents via oxidative onioation. Nat. Chem. 14, 384–391 (2022). https: / / doi.org / 10.1038 / s41557-022-00913-4), generally involve synthesizing organophosphorus transfer reagents such as phosphorus trichloride or phosphine, which are then attacked by nucleophiles to obtain the target product. However, this process inevitably results in a loss of yield due to the need for multiple steps, and both phosphine and chlorine gas required for the production of phosphorus trichloride are toxic gases, posing a high threat to operators and the environment. At the same time, a large amount of hydrogen chloride is released during this process, causing serious environmental pollution and corrosion of the equipment.

[0004] Tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite is a trivalent organophosphide containing hexafluoro groups, which has specific chemical and physical properties and has potential application value in multiple fields. Tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite can be used as a chemical processing aid, involving the processing and modification of materials such as coatings, plastics, and rubbers. In addition, due to its special chemical structure, it also has functions such as flame retardancy and anti-corrosion, and has broad application prospects in the battery field. The synthesis of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite also has the above-mentioned technical problems in the synthesis of trivalent organophosphides.

[0005] To solve the defects existing in the synthesis process of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite, the Chinese invention patent with the publication number CN114075240A discloses a synthesis method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite. The method includes the following steps: First, add hexafluoroisopropanol, triphenyl phosphite, and inorganic strong base into a reaction vessel under the full protection of inert gas; Second, stir at 30-35 °C for 16-20 h; then add water and organic solvent for extraction, and directly rectify the organic layer to obtain the target product. It has the advantages of a simple process route, high safety, and high product yield compared with the traditional method. However, this invention uses triphenyl phosphite as the phosphorus source, which is still extremely toxic to aquatic organisms and the like, and is likely to cause long-term adverse effects in the aquatic environment; it is irritating to the skin and eyes, and operators need to take additional protective measures. Moreover, from the perspective of raw material procurement, the production cost of triphenyl phosphite is relatively high. This scheme has a relatively long reaction time during the synthesis process and produces a large amount of by-products such as benzene compounds and sodium salts. These by-products are difficult to recycle and reuse, resulting in waste of raw materials and being unfavorable for reducing production costs.

[0006] In summary, providing a different synthesis route of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite outside the existing technology to meet the requirements of cost reduction, safety improvement, simplicity and speed, few by-products and high utilization value is of great significance for expanding the application of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, there is provided an electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite that is simple and fast, has high safety, few by-products, high utilization value, and low cost, including the following steps:

[0008] White phosphorus, hexafluoroisopropanol, organic base, electrolyte, and organic solvent are mixed to form an electrolytic reaction solution; the electrolytic reaction solution is electrolyzed under the action of direct current. White phosphorus is oxidized at the anode and then nucleophilically attacked by hexafluoroisopropanol to form tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite, and hydrogen atoms are reduced at the cathode to form hydrogen gas.

[0009] The overall reaction equation of the electrolysis is as follows:

[0010] 。

[0011] Preferably, in the electrolytic reaction solution, the addition amount of white phosphorus is 1 - 50 mmol; the addition amount of hexafluoroisopropanol is 1 - 10 mL; the addition amount of organic base is 0.5 - 5 mmol; the addition amount of electrolyte is 0.2 - 3 mmol; the addition amount of organic solvent is 1 - 10 mL.

[0012] To promote the activation of white phosphorus and reduce polymerization, an activation additive can be added to the electrolytic reaction solution. The activation additive can be a Lewis acid, including an acid or a salt that ionizes to be acidic in a solution environment. For example, sulfuric acid, sulfonic acid, acetic acid, and lithium salts, etc., are all suitable types of selection.

[0013] Preferably, the electrolytic reaction solution is further added with an activation additive, and the activation additive includes at least one of sulfuric acid, p-toluenesulfonic acid, sulfonic acid, acetic acid, lithium iodide, lithium chloride, and lithium sulfate.

[0014] More preferably, the molar ratio of the activation additive to white phosphorus is 1:0.2 - 10.

[0015] The organic base plays a role in promoting alcohol dehydrogenation by nucleophilic attack during electrolysis. For example, pyridine base compounds, potassium tert-butoxide, and triethylamine are all suitable types of organic bases selected in the present invention.

[0016] Preferably, the organic base includes at least one of 4-methoxypyridine, 4-methylpyridine, potassium tert-butoxide, 4-dimethylaminopyridine, and triethylamine.

[0017] In the electrolysis process, the function of the electrolyte is to increase the conductivity of the electrolyte solution, and the function of the organic solvent is to promote the dispersion of substances and create a suitable solution environment for the reaction. The electrolyte and the organic solvent should be chemically inert with respect to the substrate or the product formed by the reaction and do not react with them. Based on the reaction type of the present invention, the electrolyte can be selected from tetraethylammonium iodide, tetraethylammonium bromide, tetrabutylammonium iodide, potassium iodide, sodium iodide, sodium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride, etc. Considering the solubility of the raw materials and the solvent polarity of the present invention, the organic solvent can be selected from compounds such as dimethyl sulfoxide, acetonitrile, toluene, tetrahydrofuran, chloroform, dichloromethane, and dichloroethane.

[0018] Preferably, the electrolyte includes at least one of tetraethylammonium iodide, tetraethylammonium bromide, tetrabutylammonium iodide, potassium iodide, sodium iodide, sodium bromide, tetrabutylammonium bromide, and tetrabutylammonium chloride.

[0019] Preferably, the organic solvent includes at least one of dimethyl sulfoxide, acetonitrile, toluene, tetrahydrofuran, chloroform, dichloromethane, and dichloroethane.

[0020] The implementation of this method does not require specialized equipment, and the synthesis purpose can be achieved by using a general electrolysis device in the art, such as an integrated electrolytic cell equipped with a magnetic stir bar and electrodes. Therefore, this method has good prospects for scale-up production and industrial preparation. During the electrolysis process, no high voltage or strong current is required, the atomic utilization rate of the substrate is high, and the target product is synthesized under mild conditions.

[0021] Preferably, the current intensity of the direct current is 50 - 500 mA.

[0022] Preferably, the temperature of the electrolysis is 0 - 40 °C, and the duration of the electrolysis is 40 min - 4 h.

[0023] The selection of the cathode and anode required for electrolysis is diverse, and those skilled in the art can adopt common electrode forms. For example, carbon sheet, graphite felt, carbon cloth, platinum sheet, etc. are used as the anode, and iron sheet, carbon cloth, nickel sheet, copper sheet, nickel foam, copper foam, etc. are used as the cathode. It should be noted that as presented in one or more embodiments of the present invention, there are certain differences in the synthesis yields under different electrode selection forms, but generally they can all meet the synthesis requirements.

[0024] Preferably, the anode includes one of carbon sheet, graphite felt, carbon cloth, and platinum sheet; the cathode includes one of iron sheet, carbon cloth, nickel sheet, copper sheet, nickel foam, and copper foam.

[0025] Based on the above technical solutions, the inventive concept and principle of the present invention are as follows: Using hexafluoroisopropanol and inexpensive white phosphorus as raw materials, electrolysis is carried out under electrochemical conditions. During the electrolysis process, white phosphorus is oxidized at the anode under the action of direct current, causing the phosphorus-phosphorus bond (P-P) to break, and then hexafluoroisopropanol nucleophilically attacks it to react to obtain tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite. The electron-withdrawing groups in the tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite molecule can ensure that it is not easily peroxidized. During the nucleophilic attack process, the hydrogen atoms derived from hexafluoroisopropanol are reduced at the cathode to form hydrogen gas. The entire reaction process synthesizes the target product in one step with a high Faraday efficiency, and the only by-product is hydrogen gas with high added value. Its low solubility in the organic solvent and gaseous form are also beneficial for the separation and recovery of the by-product.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] The present invention provides an electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite, which has the advantages of being simple, fast, highly safe, having few by-products with high utilization value, and low cost; this method has a high atomic utilization rate, weak corrosiveness to the device, meets the requirements of green and safe production, and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Nuclear magnetic resonance (NMR) phosphorus ( 31 P) spectrum data diagram of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite for Example 1;

[0029] Figure 2 Nuclear magnetic resonance hydrogen ( 1 H) spectrum data diagram of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite for Example 1;

[0030] Figure 3 Nuclear magnetic resonance carbon ( 13 C) spectrum data diagram of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite for Example 1;

[0031] Figure 4 Nuclear magnetic resonance fluorine ( 19 F) spectrum data diagram of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite for Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. For the experimental methods without specific conditions noted in the following examples, they are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0033] Example 1

[0034] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite is as follows:

[0035] ;

[0036] In an argon atmosphere, 3 mmol of white phosphorus, 2 mL of hexafluoroisopropanol (HFIP), 3 mmol of 4-dimethylaminopyridine (DMAP), 1 mmol of tetrabutylammonium iodide (TBAI), and 6 mL of methyl cyanide (MeCN) were added to a reaction tube and mixed to form an electrolytic reaction solution.

[0037] A carbon plate (CP) was used as the anode, and nickel foam was used as the cathode. The electrolytic reaction solution was electrolyzed at a direct current of 100 mA at room temperature (r.t) for 3 h, and the electrolytic reaction solution was kept flowing by rotating a magnetic stirrer during the process. After electrolysis, it was purified by distillation to obtain tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite.

[0038] The NMR phosphorus spectrum, hydrogen spectrum, carbon spectrum, and fluorine spectrum data diagrams of the product tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite are shown in sequence as Figures 1-4 shown, and the target product was synthesized. The content corresponding to the peak at 140 ppm was measured to be 0.96 mmol by quantitative NMR phosphorus spectrum, and the yield of this example was 32%.

[0039] Example 2

[0040] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example was basically the same as that in Example 1, except that in this example, a graphite felt of the same specification was used as the anode. The target product was synthesized by the same method, and the yield of this example was 42%.

[0041] Example 3

[0042] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example was basically the same as that in Example 1, except that in this example, a carbon cloth of the same specification was used as the anode. The target product was synthesized by the same method, and the yield of this example was 44%.

[0043] Example 4

[0044] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example was basically the same as that in Example 1, except that in this example, a platinum sheet of the same specification was used as the anode. The target product was synthesized by the same method, and the yield of this example was 40%.

[0045] Electrolysis was carried out using different types of anodes common in the art, which had a certain impact on the yield. This might be due to differences in the power transfer efficiency and resistivity of each electrode, etc. However, overall, the purpose of synthesizing tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite was still achieved. Among them, the example using carbon cloth showed the highest yield, and carbon cloth had low cost and wide sources, making it a particularly suitable type of choice for this method.

[0046] Example 5

[0047] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite is as follows:

[0048] ;

[0049] Under an argon atmosphere, 3 mmol of white phosphorus, 2 mL of hexafluoroisopropanol, 3 mmol of potassium t-butoxide (t-BuOK), 1 mmol of tetrabutylammonium iodide, and 6 mL of acetonitrile were added to a reaction tube and mixed to form an electrolysis reaction solution;

[0050] Using carbon cloth (CC) as the anode and nickel foam as the cathode; the electrolysis reaction solution was electrolyzed at a direct current of 100 mA at room temperature for 3 h, and the electrolysis reaction solution was kept flowing by rotating a magnetic stirrer during the process; after electrolysis was completed, it was purified by distillation to obtain tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite.

[0051] The target product was synthesized using the method as in Example 1, and the yield of this example was 42%.

[0052] Example 6

[0053] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example was basically the same as that in Example 5, except that the type of organic base in this example was triethylamine. The target product was synthesized using the same method, and the yield of this example was 50%.

[0054] Example 7

[0055] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example was basically the same as that in Example 5, except that the type of organic base in this example was 4-methoxypyridine. The target product was synthesized using the same method, and the yield of this example was 31%.

[0056] Example 8

[0057] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that in Example 5, except that the type of organic base in this example is 4-methylpyridine. The target product was synthesized by the same method, and the yield of this example was 56%.

[0058] There are significant differences in the yield enhancement effects of different organic bases. In addition to meeting the requirements for synthesizing the target product, the example using 4-methylpyridine showed the highest yield, and it is appropriate to use it as the organic base to further optimize the electrolysis yield.

[0059] Example 9

[0060] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite is as follows:

[0061] ;

[0062] Under an argon atmosphere, add 3 mmol of white phosphorus, 2 mL of hexafluoroisopropanol, 0.5 mmol of sulfuric acid, 3 mmol of 4-methylpyridine, 1 mmol of tetrabutylammonium iodide, and 6 mL of acetonitrile to the reaction tube, and mix to form an electrolysis reaction solution;

[0063] Use carbon cloth as the anode and nickel foam as the cathode; electrolyze the electrolysis reaction solution at a direct current of 100 mA at room temperature for 3 h, and keep the electrolysis reaction solution flowing by rotating the magnetic stirrer during the process; after the electrolysis is completed, purify by distillation to obtain tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite.

[0064] The target product was synthesized by the method as in Example 1, and the yield of this example was 60%.

[0065] Example 10

[0066] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that in Example 9, except that the type of activation additive in this example is lithium chloride. The target product was synthesized by the same method, and the yield of this example was 44%.

[0067] Example 11

[0068] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that in Example 9, except that the type of activation additive in this example is lithium iodide. The target product was synthesized by the same method, and the yield of this example was 45%.

[0069] The yield decreases to some extent after adding lithium halide. This may be because white phosphorus with high purity is used in the examples, and adding this type of Lewis acid promotes the activation of white phosphorus. However, the rate of nucleophilic attack is limited, resulting in more white phosphorus polymerizing and deactivating at the cathode. In some cases, for example, for white phosphorus raw materials with more impurities or lower activity, adding lithium halide may be more likely to increase the yield.

[0070] Example 12

[0071] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that in Example 9, except that the type of activation additive in this example is p-toluenesulfonic acid. The target product was synthesized by the same method, and the yield of this example was 70%.

[0072] Adding activation additives helps to promote the activation of white phosphorus and reduce polymerization, which is beneficial to improving the product quality. Some activation additives, such as acids, can also increase the yield; among them, the improvement effect of toluenesulfonic acid is more significant.

[0073] Example 13

[0074] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite is as follows:

[0075] ;

[0076] Under an argon atmosphere, add 3 mmol of white phosphorus, 2 mL of hexafluoroisopropanol, 0.5 mmol of sulfuric acid, 3 mmol of 4-methylpyridine, 1 mmol of tetrabutylammonium iodide, and 6 mL of a mixed solution formed by acetonitrile and tetrahydrofuran (THF) in a volume ratio of 2:1 to a reaction tube, and mix to form an electrolytic reaction solution;

[0077] Use carbon cloth as the anode and nickel foam as the cathode; electrolyze the electrolytic reaction solution at a direct current of 100 mA at room temperature for 3 h, and keep the electrolytic reaction solution flowing by rotating a magnetic stirrer during the process; after electrolysis, purify by distillation to obtain tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite.

[0078] The target product was synthesized by the method as in Example 1, and the yield of this example was 76%.

[0079] Example 14

[0080] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that in Example 13, except that the organic solvent in this example is a mixed solution formed by acetonitrile and toluene in a volume ratio of 2:1. The target product was synthesized by the same method, and the yield in this example was 83%.

[0081] Example 15

[0082] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that in Example 13, except that the organic solvent in this example is a mixed solution formed by acetonitrile and dichloromethane in a volume ratio of 2:1. The target product was synthesized by the same method, and the yield in this example was 78%.

[0083] Example 16

[0084] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that in Example 13, except that the organic solvent in this example is a mixed solution formed by acetonitrile and dichloroethane in a volume ratio of 2:1. The target product was synthesized by the same method, and the yield in this example was 81%.

[0085] Compared with single solvent types, mixed solvents show a better effect of improving the yield. This may be because mixed solvents can provide a wider dissolution window than single solvents, which helps the dissolution of substrates; or by changing the degree of solvation to adjust the reaction rate and direction, and sometimes can reduce the activation energy of the reaction, thus accelerating the reaction process. The mixed solvent used in Example 14 shows a higher yield, and it has a wide source and low separation difficulty, making it suitable as an organic solvent for electrolysis.

[0086] Example 17

[0087] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite is as follows:

[0088] ;

[0089] Under an argon atmosphere, 3 mmol of white phosphorus, 2 mL of hexafluoroisopropanol, 0.5 mmol of sulfuric acid, 3 mmol of 4-methylpyridine, 1 mmol of tetrabutylammonium bromide (TBAB), and 6 mL of a mixed solution formed by acetonitrile and toluene (PhMe) in a volume ratio of 2:1 were added to a reaction tube and mixed to form an electrolysis reaction solution;

[0090] Using carbon cloth as the anode and nickel foam as the cathode; the electrolytic reaction solution was electrolyzed at a direct current of 100 mA at room temperature for 3 h, and the electrolytic reaction solution was kept flowing by the rotation of a magnetic stirrer during the process; after the electrolysis was completed, it was purified by distillation to obtain tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite.

[0091] The method of Example 1 was used to measure the synthesized target product, and the yield of this example was 73%.

[0092] Example 18

[0093] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that of Example 17, except that the electrolyte type in this example is tetrabutylammonium chloride. The same method was used to measure the synthesized target product, and the yield of this example was 62%.

[0094] Example 19

[0095] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that of Example 17, except that the electrolyte type in this example is sodium iodide. The same method was used to measure the synthesized target product, and the yield of this example was 85%.

[0096] Example 20

[0097] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that of Example 17, except that the electrolyte type in this example is sodium bromide. The same method was used to measure the synthesized target product, and the yield of this example was 82%.

[0098] Example 21

[0099] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that of Example 1, except that the current intensity of the direct current in this example is 50 mA, the electrolysis temperature is 0 °C, and the electrolysis duration is 4 h. The same method was used to measure the synthesized target product.

[0100] Example 22

[0101] The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite in this example is basically the same as that of Example 1, except that the current intensity of the direct current in this example is 500 mA, the electrolysis temperature is 40 °C, and the electrolysis duration is 40 min. The same method was used to measure the synthesized target product.

[0102] Comparative Example 1

[0103] This comparative example studied the effect of synthesizing tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite using other solvent types. The preparation method of this comparative example was basically the same as that of Example 13, except that the organic solvent in this example was a mixed solution formed by acetonitrile and cyclohexane in a volume ratio of 2:1. Tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite was synthesized by the method as in Example 1, but the yield of this comparative example was only 8%. The reason for the low yield may be that the polarity difference between the two solvents is too large and the solubility is poor, which is not conducive to the smooth progress of the synthesis of the target product.

[0104] Comparative Example 2

[0105] This comparative example studied the effect of synthesizing tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite using other electrolyte types. The preparation method of this comparative example was basically the same as that of Example 13, except that the electrolyte in this example was tetrabutylammonium tetrafluoroborate. Tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite was synthesized by the method as in Example 1, but the yield of this comparative example was only 7%. The reason for this result may be that tetrabutylammonium tetrafluoroborate is reactive and it participates in the process of the electrolysis reaction and generates by-products, etc., resulting in a decrease in the yield.

[0106] During the electrolysis process of the present invention, white phosphorus is oxidized at the anode under the action of direct current, causing the phosphorus-phosphorus bond to break, and then hexafluoroisopropanol nucleophilically attacks it to react to obtain tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite. The electron-withdrawing group in the tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite molecule can ensure that it is not easily peroxidized. During the nucleophilic attack process, the hydrogen atoms derived from hexafluoroisopropanol are reduced at the cathode to form hydrogen gas. The entire reaction process synthesizes the target product in one step with a high Faraday efficiency, and the only by-product is hydrogen gas with high added value. Its low solubility in the organic solvent and gaseous form are also conducive to the separation and recovery of the by-product.

[0107] In the example, the highest yield of the electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite can reach 85%, slightly higher than the best level of the prior art (CN114075240A); however, in terms of the reaction duration, this method only requires 3 h to electrolytically obtain the target product under mild conditions, while the prior art requires more than 15 h. Therefore, when applied to industrial production, the present invention has the advantages of simplicity, high speed, high safety, few by-products with high utilization value, and low cost; this method has a high atomic utilization rate and weak corrosiveness to the device, meeting the requirements of green and safe production, can greatly improve the production capacity of tris(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite, and has good industrial application prospects.

[0108] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. An electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl)phosphite, characterized in that: The steps include: White phosphorus, hexafluoroisopropanol, an organic base, an electrolyte, and an organic solvent are mixed to form an electrolytic reaction solution; the electrolytic reaction solution is electrolyzed under the action of direct current, and the white phosphorus is oxidized at the anode and then attacked by hexafluoroisopropanol to generate tris(1,1,1,3,3,3-hexafluoro-2-propyl)phosphite, and the hydrogen atoms are reduced at the cathode to form hydrogen gas; In the electrolytic reaction solution, the amount of white phosphorus added is 1-50 mmol; the amount of hexafluoroisopropanol added is 1-10 mL; the amount of organic base added is 0.5-5 mmol; the amount of electrolyte added is 0.2-3 mmol; the amount of organic solvent added is 1-10 mL; The electrolyte is one of tetrabutylammonium iodide, sodium bromide, sodium iodide, and tetrabutylammonium bromide; The organic solvent is one of acetonitrile, a mixture of acetonitrile and toluene, and a mixture of acetonitrile and dichloroethane; The electrolytic reaction solution is further added with an activation additive, which is one of sulfuric acid and p-toluenesulfonic acid; the molar ratio of the activation additive to white phosphorus is 1:0.2-10; The organic base is 4-methylpyridine; The overall reaction equation for electrolysis is as follows: 。 2. The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl)phosphite according to claim 1, characterized in that: The current intensity of the direct current is 50-500 mA.

3. The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl)phosphite according to claim 1, characterized in that: The electrolysis temperature is 0-40°C, and the electrolysis time is 40 min-4 h.

4. The electrochemical preparation method of tris(1,1,1,3,3,3-hexafluoro-2-propyl)phosphite according to claim 1, characterized in that: The anode includes one of a carbon sheet, graphite felt, carbon cloth, and a platinum sheet; the cathode includes one of an iron sheet, carbon cloth, a nickel sheet, a copper sheet, foamed nickel, and foamed copper.

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