Preparation method and application of aluminum diethylphosphinate
By using nitrogen-doped carbon quantum dot catalysts and redox radical initiation systems, the reaction temperature was reduced, and solvent selection was optimized. This solved the problems of high temperature and low efficiency in the preparation of diethylaluminum hypophosphite, achieving high purity and high yield while reducing environmental pollution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2024-11-05
- Publication Date
- 2026-06-02
AI Technical Summary
Existing methods for preparing diethylaluminum hypophosphite suffer from problems such as high reaction temperature, low efficiency, unsatisfactory purity and yield, and environmental pollution.
By using nitrogen-doped carbon quantum dots as a catalyst, combined with a redox radical initiation system of oxidant and reductant, the reaction temperature was reduced to 22-50℃, and a water-miscible gaseous organic solvent was used as the reaction solvent to optimize the reaction steps.
It improves reaction efficiency, enhances the purity and yield of diethylaluminum hypophosphite, reduces energy consumption and environmental pollution, and simplifies reaction steps.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of diethylaluminum hypophosphite synthesis technology, and specifically relates to a method for preparing and applying diethylaluminum hypophosphite. Background Technology
[0002] Currently, polymer materials are widely used in industrial materials such as plastics, rubber, and synthetic fibers. However, these materials are flammable, and once burned, they often release large amounts of deadly toxic gases. Therefore, adding flame retardants to these polymer materials to impart properties such as flame retardancy, self-extinguishing, and smoke suppression is one of the effective methods to improve their safety performance. Among many flame retardants, diethylaluminum hypophosphite is highly regarded due to its high phosphorus content of 23.85%. Its dehydration upon thermal decomposition promotes the formation of a carbon film on the polymer surface, thereby exhibiting excellent flame retardant effects.
[0003] Currently, the preparation of aluminum diethylphosphite mainly relies on two traditional methods: free radical addition and alkylation of elemental yellow phosphorus. However, these traditional methods have many drawbacks, such as excessively high reaction temperatures (generally above 120℃), unsatisfactory product purity and yield, low efficiency of gas-liquid heterogeneous reactions leading to long reaction times (generally above 6 hours), and the generation of difficult-to-treat waste, causing serious environmental pollution.
[0004] The free radical addition reaction process is relatively simple, basically involving the free radical addition reaction of hypophosphite with ethylene to produce diethyl hypophosphite. Aluminum sulfate is then used for a metathesis reaction to generate aluminum diethyl hypophosphite. Current research focuses on improving the initiator or reaction medium to increase reaction efficiency, reduce reaction difficulty, and improve product purity. Jiangsu Liside New Materials Co., Ltd. proposed an innovative method in CN103951699A, using organic solvents such as butanol as additives under low-pressure reaction conditions. This method can significantly reduce the reaction pressure and improve the safety and operability of the reaction process. Using butanol as a solvent, this system can increase the solubility of ethylene. However, this method still relies on the thermal decomposition of the initiator to generate free radicals, thus requiring the reaction to be carried out at relatively high temperatures (90-110℃). At this temperature, the increase in the solubility of ethylene in the reaction solution is still limited, which restricts its application in industrial production to some extent. Hubei Hongjia Chemical Co., Ltd. proposed a new method for synthesizing diethylaluminum hypophosphite under ultraviolet light irradiation at normal pressure and low temperature in CN109608491A. However, this method is difficult to implement in actual industrial production, and the light conversion efficiency is usually low. Once the equipment is scaled up, many practical problems arise. For example, bubbles caused by stirring and aeration devices lead to light refraction and scattering, making it difficult to initiate the reaction in the center of the reactor, resulting in low reaction efficiency and low purity. Due to the low efficiency of photo-initiation, the concentration of hypophosphite is also low when preparing it, resulting in low batch yield.
[0005] Therefore, it is of great significance to provide a method for preparing diethyl aluminum hypophosphite that has high reaction efficiency, low reaction temperature, can be scaled up for production, and has high purity and high yield. Summary of the Invention
[0006] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial solution. Specifically, the present invention provides a method for preparing diethylaluminum hypophosphite, which has high reaction efficiency, low reaction temperature, and can be scaled up for production, and the prepared diethylaluminum hypophosphite has high purity and high yield.
[0007] The inventive concept of this invention is as follows: A method for preparing diethylaluminum hypophosphite involves mixing a soluble hypophosphite with a first solvent in a reactor to obtain a soluble hypophosphite solution; replacing the air in the reactor with nitrogen and raising the temperature; introducing ethylene into the soluble hypophosphite solution in the reactor to obtain a reaction solution; then mixing an initiator, a catalyst, and the reaction solution and reacting to obtain a diethylaluminum hypophosphite solution; adding a second solvent to obtain a diluted diethylaluminum hypophosphite solution; adjusting the pH of the diluted diethylaluminum hypophosphite solution to acidic; adding an aqueous aluminum sulfate solution; and reacting to obtain the diethylaluminum hypophosphite. The initiator includes an oxidant and a reductant. This invention employs a redox free radical initiation system under catalysis, with the initiator including an oxidant and a reductant. This effectively lowers the reaction temperature to 22-50℃, improves reaction efficiency, and produces diethylaluminum hypophosphite with high purity and high yield. Furthermore, it reduces energy consumption, production costs, and environmental pollution.
[0008] Therefore, a first aspect of the present invention provides a method for preparing diethylaluminum hypophosphite.
[0009] Specifically, the preparation method of the aluminum diethylphosphite includes the following steps;
[0010] (1) The soluble hypophosphite is mixed with the first solvent in a reactor to obtain a soluble hypophosphite solution;
[0011] (2) Replace the air in the reactor with nitrogen, and then raise the temperature;
[0012] (3) Ethylene is introduced into the soluble hypophosphite solution in the reactor to obtain a reaction solution. Then, the initiator, catalyst and the reaction solution are mixed and reacted to obtain a diethyl hypophosphite solution. Then, a second solvent is added to the diethyl hypophosphite solution to obtain a diluted diethyl hypophosphite solution.
[0013] (4) Adjust the pH of the diluted diethyl hypophosphite solution obtained in step (3) to acidic, add aluminum sulfate aqueous solution, react, and obtain the diethyl hypophosphite aluminum;
[0014] The initiator includes an oxidizing agent and a reducing agent.
[0015] Preferably, the oxidant includes at least one selected from ammonium persulfate, potassium persulfate, sodium persulfate, potassium peroxymonosulfate, sodium peroxymonosulfate, and ammonium peroxymonosulfate; the reducing agent includes at least one selected from sodium sulfite, sodium bisulfite, potassium sulfite, and potassium bisulfite.
[0016] Specifically, the initiator is a redox free radical initiation system composed of an oxidant and a reductant.
[0017] Preferably, the mass ratio of the initiator to the soluble hypophosphite is (0.27-1.1):100; more preferably, the mass ratio of the initiator to the soluble hypophosphite is (0.3-1):100.
[0018] Preferably, the concentration of the aqueous solution of the oxidant is 0.1-2.0 mol / L; more preferably, the concentration of the aqueous solution of the oxidant is 0.1-1.8 mol / L.
[0019] Preferably, the concentration of the aqueous solution of the reducing agent is 0.1-2.0 mol / L; more preferably, the concentration of the aqueous solution of the reducing agent is 0.1-1.8 mol / L.
[0020] Preferably, in step (1), the soluble hypophosphite includes at least one of sodium hypophosphite, potassium hypophosphite, and ammonium hypophosphite.
[0021] Preferably, in step (1), the concentration of the soluble hypophosphite solution is 27-55 wt%; more preferably, in step (1), the concentration of the soluble hypophosphite solution is 30-50 wt%.
[0022] Preferably, in step (1), the first solvent includes water and an organic solvent.
[0023] Preferably, the organic solvent includes at least one selected from dioxane, dimethyl sulfoxide, acetonitrile, dimethylformamide, tetrahydrofuran, and acetone.
[0024] Preferably, the water content in the first solvent is 1-99% by mass; more preferably, the water content in the first solvent is 20-80% by mass.
[0025] Preferably, in step (2), during the replacement, the pressure in the reactor is maintained at 0.45-1.1 MPa; more preferably, in step (2), during the replacement, the pressure in the reactor is maintained at 0.5-1.0 MPa.
[0026] Preferably, in step (2), the temperature of the heating is 22-50℃; more preferably, in step (2), the temperature of the heating is 25-50℃.
[0027] Preferably, in step (3), the mass of ethylene introduced per hour is 13-60g relative to each mole of soluble hypophosphite in the reaction solution; more preferably, in step (3), the mass of ethylene introduced per hour is 15-56g relative to each mole of soluble hypophosphite in the reaction solution.
[0028] Preferably, in step (3), after ethylene is introduced, the pressure in the reactor is maintained at 0.45-1.1 MPa and the temperature of the reaction liquid is 22-50°C; more preferably, in step (3), after ethylene is introduced, the pressure in the reactor is maintained at 0.5-1.0 MPa and the temperature of the reaction liquid is 25-50°C.
[0029] Preferably, in step (3), the catalyst comprises nitrogen-doped carbon quantum dots.
[0030] Preferably, in step (3), the mass ratio of the catalyst to the soluble hypophosphite is (0.09-2.2):100; more preferably, in step (3), the mass ratio of the catalyst to the soluble hypophosphite is (0.1-2):100.
[0031] Preferably, in step (3), the reaction temperature is 22-50℃ and the reaction time is 0.9-2.5h; more preferably, in step (3), the reaction temperature is 25-50℃ and the reaction time is 1-2h.
[0032] Preferably, in step (3), the second solvent includes water; more preferably, the water is distilled water.
[0033] Preferably, in step (3), after adding the second solvent, the concentration of the diethyl hypophosphite solution is 18-55% of the original concentration; more preferably, in step (3), after adding the second solvent, the concentration of the diethyl hypophosphite solution is 20-50% of the original concentration.
[0034] Preferably, in step (3), after adding the second solvent, the temperature is raised to obtain a diethyl phosphite solution, and the temperature of the temperature rise is 70-95℃; more preferably, in step (3), after adding the second solvent, the temperature is raised to obtain a diethyl phosphite solution, and the temperature of the temperature rise is 75-90℃.
[0035] Preferably, in step (4), after adjusting the pH to acidic, aluminum sulfate aqueous solution is added dropwise to obtain a mixed solution, which is then reacted, the precipitate is collected, dried, and the diethyl aluminum hypophosphite is obtained.
[0036] Preferably, the pH is adjusted using an acid, including sulfuric acid.
[0037] Preferably, the pH is 2-4; more preferably, the pH is 2-3.
[0038] Preferably, the aluminum sulfate aqueous solution is a 22-60 wt% Al2(SO4)3·18H2O aqueous solution; more preferably, the aluminum sulfate aqueous solution is a 25-55 wt% Al2(SO4)3·18H2O aqueous solution.
[0039] Preferably, the mass of Al2(SO4)3·18H2O aqueous solution added per hour is 60-380 g relative to each mole of diethylphosphite in the mixture; more preferably, the mass of Al2(SO4)3·18H2O aqueous solution added per hour is 70-350 g relative to each mole of diethylphosphite in the mixture.
[0040] Preferably, the dripping time is 14-65 min; more preferably, the dripping time is 15-60 min.
[0041] Preferably, the reaction time is 1.0-2.0 h; more preferably, the reaction time is 1.0-1.5 h.
[0042] The second aspect of the present invention provides an application of the preparation method of diethylaluminum hypophosphite described in the first aspect of the present invention in the field of flame retardancy.
[0043] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:
[0044] (1) The present invention uses nitrogen-doped carbon quantum dots as catalysts. Under the action of a redox free radical initiation system including oxidants and reductants, the reaction temperature can be effectively reduced to 22-50℃, thereby improving the reaction efficiency. The prepared diethyl aluminum hypophosphite has high purity and high yield. In addition, it can reduce energy consumption, reduce production costs, and reduce environmental pollution.
[0045] (2) The present invention uses a gaseous organic solvent that is miscible with water as a reaction solvent, which can not only increase the concentration of ethylene in the reaction solution, but also maintain the solubility of soluble hypophosphite in the reaction solution. This not only simplifies the reaction steps, but also improves the efficiency and stability of the reaction system. Detailed Implementation
[0046] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.
[0047] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.
[0048] The nitrogen-doped carbon quantum dots used in the embodiments and comparative examples of this invention were all purchased from Xi'an Qiyue Biotechnology Co., Ltd.
[0049] Example 1
[0050] A method for preparing aluminum diethylphosphite includes the following steps:
[0051] (1) Soluble sodium hypophosphite, water and acetonitrile are added to the reactor and mixed and stirred to obtain a 30wt% soluble sodium hypophosphite solution, in which the mass ratio of water to acetonitrile is 2:8; the air in the reactor is replaced with nitrogen to maintain the reactor pressure at 0.7MPa. After replacement three times, the temperature is raised to 50℃.
[0052] (2) Ethylene is introduced into the sodium hypophosphite solution in the reactor at a rate of 56 g per hour relative to each mole of soluble sodium hypophosphite in the reaction solution, while maintaining the pressure in the reactor at 0.7 MPa and the temperature of the reaction solution at 50 °C.
[0053] (3) After purging the nitrogen in the reactor, add 1 mol / L sodium persulfate, 1 mol / L sodium bisulfite and nitrogen-doped carbon quantum dot aqueous solution with a mass ratio of 0.1 wt% of soluble sodium hypophosphite to the reactor. The total mass of the initiator system is 0.3% of the mass of soluble sodium hypophosphite. Maintain the reaction at 50°C for 1 h to obtain the intermediate product. Add distilled water to the solution to dilute the solution to 50% of the original concentration and then raise the temperature to 75°C to obtain diethyl sodium hypophosphite solution.
[0054] (4) After adjusting the pH of the sodium diethylphosphite solution to 2 with sulfuric acid, add 70g of 25wt% Al2(SO4)3·18H2O aqueous solution dropwise per hour for 60min, relative to each mole of sodium diethylphosphite. After the addition is complete, react for 1 hour until complete, and a white precipitate is obtained. Cool to below 50℃, filter the precipitate, wash the filter cake with distilled water, and dry it under vacuum to obtain a white powdery solid, which is aluminum diethylphosphite. The yield of the solid product is 99.21%. The method for calculating the yield of the solid product is as follows: if 1mol of soluble sodium hypophosphite is added and reacted according to the theoretical 100% yield, 1mol of sodium diethylphosphite is obtained. After reacting with aluminum sulfate according to the theoretical 100% yield, 0.33mol of aluminum diethylphosphite should be generated. The molecular weight of aluminum diethylphosphite is 390. Assuming n moles of aluminum hypophosphite are added, the yield of solid product = (actual solid product weight / (0.33n × 390)) × 100%. According to the phosphorus nuclear magnetic resonance (PNMR) spectrum analysis, the purity of diethyl aluminum hypophosphite is 99.85%.
[0055] Example 2
[0056] A method for preparing aluminum diethylphosphite includes the following steps:
[0057] (1) Add soluble potassium hypophosphite, water and dimethyl sulfoxide to the reactor and mix and stir to obtain a soluble potassium hypophosphite solution with a concentration of 40wt%, wherein the mass ratio of water to dimethyl sulfoxide is 4:6; replace the air in the reactor with nitrogen and keep the reactor pressure at 1.0MPa. After replacement three times, raise the temperature to 35℃.
[0058] (2) Ethylene is introduced into the potassium hypophosphate solution in the reactor at a rate of 15g per hour relative to each mole of potassium hypophosphate in the reaction solution, while maintaining the pressure in the reactor at 1.0MPa and the temperature of the reaction solution at 35℃.
[0059] (3) After purging the nitrogen in the reactor, add 0.1 mol / L potassium persulfate, 0.1 mol / L potassium bisulfite and nitrogen-doped carbon quantum dot aqueous solution with a mass ratio of 0.5 wt% of soluble potassium hypophosphite to the reactor. The total mass of the initiator system is 1% of the total mass of soluble potassium hypophosphite. Maintain the reaction at 35°C for 1.5 h to obtain the intermediate product. Add distilled water to the solution to dilute the solution to 40% of the original concentration and then raise the temperature to 80°C to obtain diethyl potassium hypophosphite solution.
[0060] (4) After adjusting the pH of the potassium diethylphosphite solution to 2 with sulfuric acid, 350g of a 35wt% Al2(SO4)3·18H2O aqueous solution was added dropwise per hour for 10 minutes, relative to each mole of potassium diethylphosphite. After the addition was complete, the reaction was carried out for 1.5 hours until complete, resulting in a white precipitate. The precipitate was cooled to below 50°C, filtered, and the filter cake was washed with distilled water and dried under vacuum to obtain a white powdery solid, which is aluminum diethylphosphite. The yield of the solid product was 98.96% (the calculation method of the yield of the solid product is the same as in Example 1). The purity of aluminum diethylphosphite was 99.16% according to PNMR analysis.
[0061] Example 3
[0062] A method for preparing aluminum diethylphosphite includes the following steps:
[0063] (1) Soluble sodium hypophosphite, water, acetonitrile and dimethyl sulfoxide are added to the reactor and mixed and stirred to obtain a 50wt% soluble sodium hypophosphite solution, wherein the mass ratio of water, acetonitrile and dimethyl sulfoxide is 3:6:1; the air in the reactor is replaced with nitrogen to maintain the reactor pressure at 0.5MPa. After replacement three times, the temperature is raised to 40℃.
[0064] (2) Ethylene is introduced into the soluble sodium hypophosphite solution in the reactor at a rate of 20 g per hour relative to each mole of soluble sodium hypophosphite in the reaction solution, while maintaining the pressure in the reactor at 0.5 MPa and the temperature of the reaction solution at 40 °C.
[0065] (3) After purging the nitrogen in the reactor, add 1.8 mol / L sodium persulfate, 1.8 mol / L sodium bisulfite and nitrogen-doped carbon quantum dot aqueous solution at a mass ratio of 2 wt% of soluble sodium hypophosphite into the reactor. The total mass of the initiator system is 0.8% of the mass of soluble sodium hypophosphite. Maintain the reaction at 40°C for 1.5 h to obtain the intermediate product. Add distilled water to the solution to dilute the reaction solution to 45% of the original concentration and then raise the temperature to 85°C to obtain diethyl sodium hypophosphite solution.
[0066] (4) After adjusting the pH of the sodium diethylphosphite solution to 3 with sulfuric acid, 300g of a 45wt% Al2(SO4)3·18H2O aqueous solution was added dropwise per hour for 15 minutes, relative to each mole of sodium diethylphosphite. After the addition was complete, the reaction was carried out for 1.5 hours until complete, resulting in a white precipitate. The precipitate was cooled to below 50°C, filtered, and the filter cake was washed with distilled water and dried under vacuum to obtain a white powdery solid, which is aluminum diethylphosphite. The yield of the solid product was 98.65% (the method for calculating the yield of the solid product is the same as in Example 1). The purity of aluminum diethylphosphite was 99.77% according to PNMR analysis.
[0067] Example 4
[0068] A method for preparing aluminum diethylphosphite includes the following steps:
[0069] (1) Add soluble ammonium hypophosphite, water and dimethyl sulfoxide to the reactor and mix and stir to obtain a soluble sodium hypophosphite solution with a concentration of 30wt%, wherein the mass ratio of water to dimethyl sulfoxide is 7:3; replace the air in the reactor with nitrogen and keep the reactor pressure at 1.0MPa. After replacement three times, raise the temperature to 30℃.
[0070] (2) Ethylene is introduced into the soluble ammonium hypophosphite solution in the reactor at a rate of 30 g per hour relative to each mole of ammonium hypophosphite in the reaction solution, while maintaining the pressure in the reactor at 1.0 MPa and the temperature of the reaction solution at 30°C.
[0071] (3) After purging the nitrogen in the reactor, add sodium persulfate with a concentration of 1.3 mol / L, sodium bisulfite with a concentration of 1.3 mol / L, and nitrogen-doped carbon quantum dot aqueous solution with a mass ratio of 0.5 wt% of soluble hypophosphite to the reactor. The total mass of the initiator system is 0.5% of the mass of soluble sodium hypophosphite. Maintain the reaction at 30°C for 2 hours to obtain an intermediate product. Add distilled water to the solution to dilute the reaction solution to 35% of the original concentration and then raise the temperature to 90°C to obtain a diethylammonium hypophosphite solution.
[0072] (4) After adjusting the pH of the diethylammonium hypophosphite solution to 2 with sulfuric acid, 100g of a 40wt% Al2(SO4)3·18H2O aqueous solution was added dropwise per hour for 50min, relative to each mole of diethylammonium hypophosphite. After the addition was complete, the reaction was carried out for 1 hour until complete, resulting in a white precipitate. The precipitate was cooled to below 50℃, filtered, and the filter cake was washed with distilled water and dried under vacuum to obtain a white powdery solid, which is diethylaluminum hypophosphite. The yield of the solid product was 99.23% (the method for calculating the yield of the solid product is the same as in Example 1). The purity of diethylaluminum hypophosphite was 98.91% according to PNMR analysis.
[0073] Example 5
[0074] A method for preparing aluminum diethylphosphite includes the following steps:
[0075] (1) Soluble sodium hypophosphite, water and dioxane were added to the reactor and mixed and stirred to obtain a soluble sodium hypophosphite solution with a concentration of 30wt%, wherein the mass ratio of water to dioxane was 3:7; the air in the reactor was replaced with nitrogen to maintain the reactor pressure at 0.8MPa. After replacement three times, the temperature was raised to 30℃.
[0076] (2) Ethylene is introduced into the soluble sodium hypophosphite solution in the reactor at a rate of 40 g per hour relative to each mole of soluble sodium hypophosphite in the reaction solution, while maintaining the pressure in the reactor at 0.8 MPa and the temperature of the reaction solution at 30 °C.
[0077] (3) After purging the nitrogen in the reactor, add 0.8 mol / L sodium persulfate, 0.8 mol / L sodium bisulfite and nitrogen-doped carbon quantum dot aqueous solution at a mass ratio of 1 wt% of soluble sodium hypophosphite to the reactor. The total mass of the initiator system is 0.7% of the mass of soluble sodium hypophosphite. Maintain the reaction at 30°C for 1.5 h to obtain the intermediate product. Add distilled water to the solution to dilute the reaction solution to 25% of the original concentration and then raise the temperature to 75°C to obtain diethyl sodium hypophosphite solution.
[0078] (4) After adjusting the pH of the sodium diethylphosphite solution to 2 with sulfuric acid, 150g of a 55wt% Al2(SO4)3·18H2O aqueous solution was added dropwise per hour for 25min, relative to each mole of sodium diethylphosphite. After the addition was complete, the reaction was carried out for 1.2 hours until complete, resulting in a white precipitate. The precipitate was cooled to below 50℃, filtered, and the filter cake was washed with distilled water and dried under vacuum to obtain a white powdery solid, i.e., 126.98g of aluminum diethylphosphite. The yield of the solid product was 98.66% (the calculation method of the yield of the solid product is the same as in Example 1). The purity of aluminum diethylphosphite was 99.76% according to PNMR analysis.
[0079] Example 6
[0080] A method for preparing aluminum diethylphosphite includes the following steps:
[0081] (1) Add soluble potassium hypophosphite, water and dimethylformamide to the reactor and mix and stir to obtain a soluble potassium hypophosphite solution with a concentration of 30wt%, wherein the mass ratio of water and dimethylformamide is 4:6; replace the air in the reactor with nitrogen and keep the reactor pressure at 0.6MPa. After replacement three times, raise the temperature to 30℃.
[0082] (2) Ethylene is introduced into the soluble potassium hypophosphite solution in the reactor at a rate of 15 g per hour relative to each mole of soluble potassium hypophosphite in the reaction solution, while maintaining the pressure in the reactor at 0.6 MPa and the temperature of the reaction solution at 30°C.
[0083] (3) After purging the nitrogen in the reactor, add 0.15 mol / L potassium persulfate, 0.15 mol / L potassium bisulfite and nitrogen-doped carbon quantum dot aqueous solution with a mass ratio of 1.5 wt% of soluble potassium hypophosphite to the reactor. The total mass of the initiator system is 0.5% of the mass of soluble sodium hypophosphite. Maintain the reaction at 30°C for 2 hours to obtain an intermediate product. Add distilled water to the solution to dilute the reaction solution to 35% of the original concentration and then raise the temperature to 85°C to obtain a diethyl potassium hypophosphite solution.
[0084] (4) After adjusting the pH of the potassium diethylphosphite solution to 2 with sulfuric acid, 200g of a 50wt% Al2(SO4)3·18H2O aqueous solution was added dropwise per hour for 20min, relative to each mole of potassium diethylphosphite. After the addition was complete, the reaction was carried out for 1.5 hours until complete, resulting in a white precipitate. The precipitate was cooled to below 50℃, filtered, and the filter cake was washed with distilled water and dried under vacuum to obtain a white powdery solid, which is aluminum diethylphosphite. The yield of the solid product was 99.32% (the calculation method of the yield of the solid product is the same as in Example 1). The purity of aluminum diethylphosphite was 99.63% according to PNMR analysis.
[0085] Example 7
[0086] A method for preparing aluminum diethylphosphite includes the following steps:
[0087] (1) Soluble sodium hypophosphite, water and acetonitrile are added to the reactor and mixed and stirred to obtain a 40wt% soluble sodium hypophosphite solution, in which the mass ratio of water and acetonitrile is 5:5; the air in the reactor is replaced with nitrogen to maintain the reactor pressure at 0.9MPa. After replacement three times, the temperature is raised to 30℃.
[0088] (2) Ethylene is introduced into the soluble sodium hypophosphite solution in the reactor at a rate of 25 g per hour relative to each mole of soluble sodium hypophosphite in the reaction solution, while maintaining the pressure in the reactor at 0.9 MPa and the temperature of the reaction solution at 30 °C.
[0089] (3) After purging the nitrogen in the reactor, add 1.2 mol / L sodium persulfate, 1.2 mol / L sodium bisulfite and nitrogen-doped carbon quantum dot aqueous solution at a mass ratio of 1 wt% of soluble sodium hypophosphite to the reactor. The total mass of the initiator system is 0.8% of the mass of soluble sodium hypophosphite. Maintain the reaction at 50°C for 1 h to obtain the intermediate product. Add distilled water to the solution to dilute the reaction solution to 20% of the original concentration and then raise the temperature to 80°C to obtain diethyl sodium hypophosphite solution.
[0090] (4) After adjusting the pH of the sodium diethylphosphite solution to 2 with sulfuric acid, 200g of a 45wt% Al2(SO4)3·18H2O aqueous solution was added dropwise per hour for 25 minutes, relative to each mole of sodium diethylphosphite. After the addition was complete, the reaction was carried out for 1 hour until complete, resulting in a white precipitate. The precipitate was cooled to below 50°C, filtered, and the filter cake was washed with distilled water and dried under vacuum to obtain a white powdery solid, which is aluminum diethylphosphite. The yield of the solid product was 99.36% (the method for calculating the yield of the solid product is the same as in Example 1). The purity of aluminum diethylphosphite was 99.48% according to PNMR analysis.
[0091] Example 8
[0092] A method for preparing aluminum diethylphosphite includes the following steps:
[0093] (1) Soluble sodium hypophosphite, water, acetonitrile and dimethylformamide were added to the reactor and mixed and stirred to obtain a 30wt% soluble sodium hypophosphite solution, wherein the mass ratio of water, acetonitrile and dimethylformamide was 4:3:3; the air in the reactor was replaced with nitrogen to maintain the reactor pressure at 0.8MPa. After replacement three times, the temperature was raised to 40℃.
[0094] (2) Ethylene is introduced into the soluble sodium hypophosphite solution in the reactor at a rate of 20 g per hour relative to each mole of soluble sodium hypophosphite in the reaction solution, while maintaining the pressure in the reactor at 0.8 MPa and the temperature of the reaction solution at 40 °C.
[0095] (3) After purging the nitrogen in the reactor, add 1.5 mol / L sodium persulfate, 1.5 mol / L sodium bisulfite and nitrogen-doped carbon quantum dot aqueous solution at a mass ratio of 1 wt% of soluble sodium hypophosphite to the reactor. The total mass of the initiator system is 0.6% of the mass of sodium hypophosphite. Maintain the reaction at 40°C for 1 h to obtain the intermediate product. Add distilled water to the solution to dilute the reaction solution to 30% of the original concentration and then raise the temperature to 75°C to obtain diethyl sodium hypophosphite solution.
[0096] (4) After adjusting the pH of the sodium diethylphosphite solution to 2 with sulfuric acid, 100g of a 45wt% Al2(SO4)3·18H2O aqueous solution was added dropwise per hour relative to each mole of sodium diethylphosphite for 50 minutes. After the addition was complete, the reaction was carried out for 1 hour until complete, resulting in a white precipitate. The precipitate was cooled to below 50°C, filtered, and the filter cake was washed with distilled water and dried under vacuum to obtain a white powdery solid, which is aluminum diethylphosphite. The yield of the solid product was 99.17% (the method for calculating the yield of the solid product is the same as in Example 1). The purity of aluminum diethylphosphite was 99.48% according to PNMR analysis.
[0097] Comparative Example 1
[0098] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, step (3) did not involve adding nitrogen-doped carbon quantum dot aqueous solution, while the rest was the same as in Example 1, resulting in a solid product, namely aluminum diethylphosphite, with a solid product yield of 98.21% (the calculation method for the solid product yield is the same as in Example 1). PNMR analysis showed that the purity of aluminum diethylphosphite was 31.03%.
[0099] Comparative Example 2
[0100] The only difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the initiator system in step (3) does not contain sodium bisulfate aqueous solution, but only sodium persulfate aqueous solution with a concentration of 1 mol / L. The rest is the same as in Example 1. After 1 hour, it was found that the ethylene consumption was basically zero, indicating that the reaction was not initiated.
[0101] In summary, this invention utilizes nitrogen-doped carbon quantum dots as a catalyst, and under the action of a redox radical initiation system composed of oxidants and reductants, the reaction temperature can be effectively reduced to 25-50℃, improving reaction efficiency. Furthermore, the prepared diethylaluminum hypophosphite exhibits high purity and high yield. In addition, it reduces energy consumption, production costs, and environmental pollution. Moreover, this invention uses a water-miscible gaseous organic solvent as the reaction solvent, which increases the concentration of ethylene in the reaction solution while maintaining the solubility of soluble hypophosphite. This not only simplifies the reaction steps but also improves the efficiency and stability of the reaction system.
[0102] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A method for preparing diethylaluminum hypophosphite, characterized in that, Includes the following steps: (1) The soluble hypophosphite is mixed with the first solvent in a reactor to obtain a soluble hypophosphite solution; (2) Replace the air in the reactor with nitrogen and raise the temperature; (3) Ethylene is introduced into the soluble hypophosphite solution in the reactor to obtain a reaction solution. The initiator, catalyst and the reaction solution are then mixed and reacted to obtain a diethyl hypophosphite solution. Then a second solvent is added to the diethyl hypophosphite solution to obtain a diluted diethyl hypophosphite solution. (4) Adjust the pH of the diluted diethyl hypophosphite solution obtained in step (3) to acidic, add aluminum sulfate aqueous solution, react, and obtain the diethyl hypophosphite aluminum; The initiator consists of an oxidizing agent and a reducing agent; The oxidizing agent is selected from at least one of ammonium persulfate, potassium persulfate, sodium persulfate, potassium peroxymonosulfate, sodium peroxymonosulfate, and ammonium peroxymonosulfate; the reducing agent is selected from at least one of sodium sulfite, sodium bisulfite, potassium sulfite, and potassium bisulfite. In step (1), the first solvent is water and an organic solvent; The concentration of the soluble hypophosphite solution is 27-55 wt%. In step (3), the catalyst is nitrogen-doped carbon quantum dots.
2. The preparation method according to claim 1, characterized in that, The mass ratio of the initiator to the soluble hypophosphite is (0.27-1.1):
100.
3. The preparation method according to claim 1, characterized in that, In step (1), the soluble hypophosphite is selected from at least one of sodium hypophosphite, potassium hypophosphite, and ammonium hypophosphite.
4. The preparation method according to claim 1, characterized in that, The organic solvent is selected from at least one of dioxane, dimethyl sulfoxide, acetonitrile, dimethylformamide, tetrahydrofuran, and acetone.
5. The preparation method according to claim 1, characterized in that, In the first solvent, the mass percentage of water is 1-99%.
6. The preparation method according to claim 1, characterized in that, In step (2), during the replacement, the pressure in the reactor is maintained at 0.45-1.1 MPa.
7. The preparation method according to claim 1, characterized in that, In step (2), the temperature for heating is 22-50℃.
8. The preparation method according to claim 1, characterized in that, In step (3), the mass of ethylene introduced per hour is 13-60g relative to each mole of soluble hypophosphite in the reaction solution.
9. The preparation method according to claim 1, characterized in that, In step (3), after ethylene is introduced, the pressure in the reactor is maintained at 0.45-1.1 MPa and the temperature of the reaction liquid is 22-50℃.
10. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of the catalyst to the soluble hypophosphite is (0.09-2.2):
100.
11. The preparation method according to claim 1, characterized in that, In step (3), the reaction temperature is 22-50℃ and the reaction time is 0.9-2.5h.
12. The preparation method according to claim 1, characterized in that, In step (3), the second solvent is water.
13. The preparation method according to claim 1, characterized in that, In step (3), after adding the second solvent, the concentration of the diethyl hypophosphite solution is 18-55% of the original concentration.
14. The preparation method according to claim 1, characterized in that, In step (3), after adding the second solvent, the temperature is raised to obtain a diethyl phosphite solution, and the temperature of the temperature rise is 70-95℃.
15. The preparation method according to claim 1, characterized in that, In step (4), after adjusting the pH to acidic, aluminum sulfate aqueous solution is added dropwise to obtain a mixed solution. Then, the mixture is reacted, the precipitate is collected, dried, and the diethyl aluminum hypophosphite is obtained.
16. The preparation method according to claim 15, characterized in that, The aluminum sulfate aqueous solution is 22-60 wt% Al2(SO4)3 18H2O aqueous solution.
17. The preparation method according to claim 15, characterized in that, Al2(SO4)3 is added dropwise per hour relative to each mole of diethylphosphite in the mixture. The mass of the 18H2O aqueous solution is 60-380g.
18. The preparation method according to claim 15, characterized in that, The dripping time is 14-65 minutes.
19. The preparation method according to claim 15, characterized in that, The reaction time is 1.0-2.0 h.
20. The application of the preparation method according to any one of claims 1-19 in the field of flame retardancy.