Method for preparing diisobutyl aluminum phosphinate by using microchannel reactor

Abstract

The invention discloses a method for preparing diisobutyl aluminum phosphinate by using a micro-channel reactor, which comprises the following steps of: synthesizing an intermediate diisobutyl phosphinic acid in a micro-channel reactor with strong mass and heat transfer through liquid-phase oxidation by taking diisobutyl phosphine as an initial raw material; and reacting with a sodium source and an aluminum source in the pipeline reactor in sequence to finish the continuous flow process of the diisobutyl aluminum phosphinate. By utilizing the excellent mass transfer and heat exchange performance of the micro-channel reactor, not only is the reaction time greatly shortened, but also compared with the traditional kettle reaction, the loss caused by dropwise adding the oxidant and the risk that the raw material diisobutylphosphine is easy to spontaneously ignite and the reaction oxidation heat release is easy to spray are reduced, the safe production of the diisobutylphosphinic acid aluminum is realized, and the production cost is reduced. The method has the advantages of high efficiency, energy conservation, easiness in control, few three wastes and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a method for preparing aluminum diisobutylphosphinate by utilizing a microchannel reactor. Background Art

[0002] With the continuous development of modern industry, polymer materials such as coatings, rubbers, and synthetic fibers are widely used in daily life due to their good physical and mechanical properties. However, the flammability of these polymer materials themselves is accompanied by great safety hazards. Therefore, it is crucial to achieve flame retardant modification of polymer materials and solve the ecological and environmental problems caused by halogenated flame retardants. Among the many flame retardants currently developed, alkyl phosphinates have the characteristics of high thermal stability, less addition, less volatility, low toxicity, and good water resistance. Therefore, they have attracted much attention and have a very important position in the field of flame retardancy.

[0003] At present, a variety of synthesis methods have been developed for aluminum diisobutylphosphinate, but some common preparation processes often involve a large amount of concentrated acid, initiator, and catalyst, and require high corrosion resistance of the equipment, and it is difficult to accurately control the dosage and reaction temperature during the reaction. The present invention uses a microchannel reactor with high mass transfer and heat transfer performance and a special microstructure to effectively control the concentration distribution of the oxidant, so that the materials in the reaction process are efficiently mixed. In addition, the present invention also solves the safety problems of the traditional kettle reaction, such as the cumbersome operation, the easy spontaneous combustion of the raw material diisobutylphosphine, the difficulty in temperature control during the oxidation process, and the easy spraying of materials. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing aluminum diisobutylphosphinate using a microchannel reactor, which uses hydrogen peroxide as an oxidant, is environmentally friendly, does not involve concentrated acid or catalyst in the reaction process, and greatly shortens the reaction time and improves the reaction rate compared to the traditional synthesis process. More importantly, the efficient heat transfer efficiency of the microchannel reactor can transfer the heat generated instantly by the oxidation reaction in a timely manner, which greatly increases the safety factor.

[0005] The technical solution of the present invention is as follows: A method for preparing aluminum diisobutylphosphinate using a microchannel reactor comprises the following steps: S1, respectively delivering the diisobutyl phosphine solution and the oxidant solution to the coil for precooling by a plunger pump, and then respectively pumping them into the first premixing module in the microchannel reactor, and after being fully premixed, sequentially pumping them into the first reaction module, the second reaction module, and the third reaction module for gradient heating to complete the liquid-phase oxidation of diisobutyl phosphine to obtain a mixed solution; S2, then, the outflowing mixed solution is pumped into the pipeline reactor, and sequentially mixed with the introduced sodium source and aluminum source for reaction; S3. After the reaction is completed, the product diisobutyl aluminum phosphinate can be obtained by vacuum filtration, washing the filter cake, and drying.

[0006] In the above technical solution, the preferred oxidant includes one or more of tert-butyl hydroperoxide, sodium hypochlorite, potassium permanganate, hydrogen peroxide, and manganese dioxide, and the concentration of the oxidant during the feeding process is 4-10 mol / L.

[0007] In the above technical solution, the flow rates of the diisobutylphosphine solution and the oxidant solution to the coil, the first premixing module, and the reaction module are 1.0-5.0 mL / min and 0.1-10.0 mL / min, respectively.

[0008] In the above technical scheme, the microchannel reactor is a Corning microchannel G1 glass reactor, which is a heart-shaped microchannel with heat exchange plate layers on both the upper and lower surfaces, and the heat transfer oil is used as the medium in the layer, and the set temperature control is achieved by an external heat exchanger. The liquid holding capacity of each module is 7~10 mL (i.e., 70-100% of the volume fraction), and the overall microreactor is composed of one or multiple reaction modules connected in series. In this case, three reaction modules are taken as an example. When there are more, the reaction process of this case is also realized continuously, which is also the protection reaction of this case.

[0009] In the above technical solution, the liquid holding capacity of the precooling coil is 50-100% of the coil volume.

[0010] In the above technical solution, the diisobutylphosphine solution or oxidant solution is precooled to 2-10°C in the coil; The multiple modules in the microreactor are temperature-controlled in temperature zones, the plate temperature of the first premixing module is 2-10°C, the plate temperature of the first reaction module is 20-30°C, the plate temperature of the second reaction module is 40-60°C, and the plate temperature of the third reaction module is 60-80°C.

[0011] In the above technical solution, the residence time in the microchannel reactor is 5 to 30 minutes.

[0012] In the above technical solution, in step S2, the sodium source includes one or more of sodium carbonate, sodium hydroxide, sodium bicarbonate, sodium sulfate, and sodium sulfite.

[0013] The aluminum source includes one or more of anhydrous aluminum chloride, aluminum sulfate 18-hydrate, aluminum hydroxide, and aluminum chloride hexahydrate.

[0014] The molar ratio of the diisobutylphosphine, the oxidant, the sodium source and the aluminum source is 1:0.8-1.0:1.0-1.2:0.1-0.3. In the above technical solution, the temperature in the pipeline reactor is 80~100°C.

[0015] In the above technical solution, the solvent for washing the filter cake is one or more of deionized water, methanol, ethanol, dichloromethane, and ethyl acetate.

[0016] The present invention provides a method for preparing aluminum diisobutylphosphinate by using a microchannel reactor. The method uses diisobutylphosphine as a starting material and synthesizes diisobutylphosphinic acid by using a microchannel reactor. Then, the feeding of a sodium source and an aluminum source is completed in sequence through a pipeline reactor. After the reaction is completed, the product aluminum diisobutylphosphinate can be obtained by vacuum filtration, washing and drying. The synthesis method of aluminum diisobutylphosphinate provided by the present invention does not involve concentrated acid or a catalyst, reduces the reaction cost, shortens the reaction time and improves the reaction rate by using a microchannel reactor. In addition, the safety risk brought by the exothermic oxidation reaction is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0018] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the intermediate diisobutylphosphinic acid in Example 5. DETAILED DESCRIPTION

[0019] The present invention is further described below with reference to embodiments, but the scope of protection claimed by the present invention is not limited to the scope described in the embodiments.

[0020] Example 1 In the process of preparing aluminum diisobutylphosphinate using a microchannel reactor, the reaction residence time is kept constant and the concentration and dosage of the oxidant are optimized, including the following experimental steps: Add diisobutylphosphine and hydrogen peroxide to the liquid storage bottle, and use a metering pump to transport the two liquids to the coil through a T-type mixing valve for rapid precooling. After reaching a precooling temperature of 5°C, pump it into the microchannel reactor. Adjust the flow rate of diisobutylphosphine and hydrogen peroxide of different concentrations in the microchannel reaction device. And control the plate temperature of the material in the first premixing module to be 5°C. After sufficient premixing, the effluent passes through the first reaction module, the second reaction module and the third reaction module at the corresponding flow rate (as shown in the following table). Among them, the temperature of the first reaction module is 20°C, the temperature of the second reaction module is 40°C, and the temperature of the third reaction module is 60°C. After staying in the premixing module and the first, second and third reaction modules for 8 minutes, the outflowing reaction liquid is pumped into a 100°C pipeline reactor and mixed with 20% sodium hydroxide aqueous solution again. Next, 0.17 equivalents of 18-hydrate aluminum sulfate aqueous solution are introduced and heated at 100°C for 5 minutes. After the reaction is completed, the product diisobutyl aluminum phosphinate can be obtained by vacuum filtration, washing with deionized water 2 to 3 times and drying.

[0021]

[0022] Example 2 Diisobutylphosphine and hydrogen peroxide were added to the liquid storage bottle, and the two liquids were transported to the coil through the T-type mixing valve by a metering pump for rapid precooling. After reaching the precooling temperature of 5 ℃, they were pumped into the microchannel reactor. Among them, the flow rates of diisobutylphosphine and hydrogen peroxide (9.79 mol / L) in the microreactor were 3.57 mL / min and 0.53 mL / min, respectively. The plate temperature of the microreactor was controlled to be 60 ℃. After staying in the reaction module for 8 min, the outflowing reaction liquid entered the 100 ℃ pipeline reactor and then mixed with 20% sodium hydroxide aqueous solution for reaction. Then, 0.17 equivalents of 18-hydrated aluminum sulfate aqueous solution were introduced, and the reaction was heated at 100 ℃ for 5 min. After the reaction was completed, the product diisobutyl aluminum phosphinate was obtained by vacuum filtration, washing with deionized water 2-3 times, and drying, with a yield of 42.1%.

[0023] Example 3 Diisobutylphosphine and hydrogen peroxide were added to the liquid storage bottle, and the two liquids were transported to the coil through the T-type mixing valve by a metering pump for rapid precooling. After reaching the precooling temperature of 5 ℃, they were pumped into the microchannel reactor. Among them, the flow rates of diisobutylphosphine and hydrogen peroxide (9.79 mol / L) in the microreactor were 1.79 mL / min and 0.26 mL / min, respectively. And the plate temperature of the material in the first premixing module was controlled to be 5 ℃. After sufficient premixing, the effluent passed through the first reaction module, the second reaction module and the third reaction module in turn. Among them, the temperature of the first reaction module was 20 ℃, the temperature of the second reaction module was 40 ℃, and the temperature of the third reaction module was 60 ℃. After staying in the premixing module and the first, second and third reaction modules for 16 min, the outflowing reaction liquid was pumped into the 100 ℃ pipeline reactor and mixed with 20% sodium hydroxide aqueous solution again for reaction. Then, 0.17 equivalent of aluminum sulfate 18hydrate aqueous solution was introduced, and the reaction was heated at 100°C for 5 min. After the reaction was completed, the product was filtered under reduced pressure, washed with deionized water 2-3 times, and dried to obtain the product aluminum diisobutylphosphinate with a yield of 84.5%.

[0024] Example 4 Diisobutylphosphine and hydrogen peroxide were added to the liquid storage bottle, and the two liquids were transported to the coil through the T-type mixing valve by a metering pump for rapid precooling. After reaching the precooling temperature of 5 ℃, they were pumped into the microchannel reactor. Among them, the flow rates of diisobutylphosphine and hydrogen peroxide (9.79 mol / L) in the microreactor were 1.19 mL / min and 0.18 mL / min, respectively. The plate temperature of the introduced material in the first premixing module was 5 ℃. After sufficient premixing, the effluent passed through the first reaction module, the second reaction module and the third reaction module in turn. Among them, the temperature of the first reaction module was 20 ℃, the temperature of the second reaction module was 40 ℃, and the temperature of the third reaction module was 60 ℃. After staying in the premixing module and the first, second and third reaction modules for 24 min, the outflowing reaction liquid was pumped into the 100 ℃ pipeline reactor and mixed with 20% sodium hydroxide aqueous solution again for reaction. Then, 0.17 equivalent of aluminum sulfate 18hydrate aqueous solution was introduced, and the mixture was heated at 100°C for 5 min. After the reaction was completed, the mixture was filtered under reduced pressure, washed with deionized water 2-3 times, and dried to obtain the product aluminum diisobutylphosphinate, with a yield of 87.6%.

[0025] Example 5 Diisobutylphosphine and hydrogen peroxide were added to the liquid storage bottle, and the two liquids were transported to the coil through the T-type mixing valve by a metering pump for rapid precooling. After reaching the precooling temperature of 5 ℃, they were pumped into the microchannel reactor. Among them, the flow rates of diisobutylphosphine and hydrogen peroxide (9.79mol / L) in the microreactor were 1.19 mL / min and 0.18 mL / min, respectively. The plate temperature of the introduced material in the first premixing module was 5 ℃. After sufficient premixing, the effluent passed through the first reaction module, the second reaction module and the third reaction module in turn. Among them, the temperature of the first reaction module was 30 ℃, the temperature of the second reaction module was 50 ℃, and the temperature of the third reaction module was 80 ℃. After staying in the premixing module and the first, second and third reaction modules for 24 min, the outflowing reaction liquid was pumped into the 100 ℃ pipeline reactor and mixed with 20% sodium hydroxide aqueous solution again for reaction. Then, 0.17 equivalent of aluminum sulfate 18hydrate aqueous solution was introduced, and the reaction was heated at 100°C for 5 min. After the reaction was completed, the product was filtered under reduced pressure, washed with deionized water 2-3 times, and dried to obtain the product aluminum diisobutylphosphinate with a yield of 97.1%.

[0026] Example 6 Diisobutylphosphine and hydrogen peroxide were added to the liquid storage bottle, and the two liquids were transported to the coil through the T-type mixing valve by a metering pump for rapid precooling. After reaching the precooling temperature of 5 ℃, they were pumped into the microchannel reactor. Among them, the flow rates of diisobutylphosphine and hydrogen peroxide (9.79 mol / L) in the microreactor were 1.19 mL / min and 0.18 mL / min, respectively. The plate temperature of the introduced material in the first premixing module was 5 ℃. After sufficient premixing, the effluent passed through the first reaction module, the second reaction module and the third reaction module in turn. Among them, the temperature of the first reaction module was 30 ℃, the temperature of the second reaction module was 60 ℃, and the temperature of the third reaction module was 80 ℃. After staying in the premixing module and the first, second and third reaction modules for 24 min, the outflowing reaction liquid was pumped into the 80 ℃ pipeline reactor and mixed with 20% sodium carbonate aqueous solution again for reaction. Then, 0.33 equivalent of aluminum chloride hexahydrate aqueous solution was introduced, and the mixture was heated at 100°C for 5 min. After the reaction was completed, the mixture was filtered under reduced pressure, washed with deionized water 2-3 times, and dried to obtain the product aluminum diisobutylphosphinate, with a yield of 85.5%.

[0027] Example 7 Diisobutylphosphine and hydrogen peroxide were added to the liquid storage bottle, and the two liquids were transported to the coil through the T-type mixing valve by a metering pump for rapid precooling. After reaching the precooling temperature of 5°C, they were pumped into the microchannel reactor. Among them, the flow rates of diisobutylphosphine and hydrogen peroxide (9.79mol / L) in the microreactor were 1.19 mL / min and 0.18 mL / min, respectively. The plate temperature of the introduced material in the first premixing module was 5°C. After sufficient premixing, the effluent passed through the first reaction module, the second reaction module and the third reaction module in turn. Among them, the temperature of the first reaction module was 30°C, the temperature of the second reaction module was 50°C, and the temperature of the third reaction module was 80°C. After staying in the premixing module and the first, second and third reaction modules for 24 minutes, the outflowing reaction liquid was pumped into the 100°C pipeline reactor and mixed with 20% sodium hydroxide aqueous solution again for reaction. Then, 0.17 equivalent of aluminum sulfate 18hydrate aqueous solution was introduced, and the mixture was heated at 100°C for 5 min. After the reaction was completed, the mixture was filtered under reduced pressure, washed with dichloromethane 2-3 times, and dried to obtain the product aluminum diisobutylphosphinate, with a yield of 93.3%.

[0028] It can be seen from the above embodiments that the above description of the present invention is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing aluminum diisobutylphosphinate using a microchannel reactor, characterized in that: The steps include: S1, respectively transporting the diisobutyl phosphine solution and the oxidant solution to the precooling coil by a plunger pump for precooling, and then pumping them into the first premixing module in the microchannel reactor respectively, and after being fully premixed, sequentially pumping them into the first reaction module, the second reaction module, and the third reaction module for gradient heating to complete the liquid-phase oxidation of diisobutyl phosphine to obtain a mixed solution; S2, then, the outflowing mixed solution is pumped into the pipeline reactor, and sequentially mixed with the introduced sodium source and aluminum source for reaction; S3. After the reaction is completed, the product diisobutyl aluminum phosphinate can be obtained by vacuum filtration, washing the filter cake, and drying.

2. The preparation method according to claim 1, characterized in that: The oxidant includes one or more of tert-butyl hydroperoxide, sodium hypochlorite, potassium permanganate, hydrogen peroxide, and manganese dioxide. The concentration of the oxidant during the feeding process is 4-10 mol / L.

3. The preparation method according to claim 1, characterized in that: The flow rates of the diisobutylphosphine solution and the oxidant solution to the coil, the first premixing module, and the reaction module are 1.0-5.0 mL / min and 0.1-10.0 mL / min, respectively.

4. The preparation method according to claim 1, characterized in that: The microchannel reactor is a Corning microchannel G1 glass reactor with a heart-shaped microchannel, heat exchange plate layers on both the upper and lower surfaces, and heat transfer oil as the medium in the layer, and an external heat exchanger is used to achieve the set temperature control.

5. The preparation method according to claim 3, characterized in that: The liquid holding capacity of the precooling coil is 50-100% of the coil volume.

6. The preparation method according to claim 4, characterized in that: The diisobutylphosphine solution or oxidant solution is precooled to 2-10°C in a precooling coil; The modules in the microchannel reactor are temperature-zone controlled, the plate temperature of the first premixing module is 2~10°C, the plate temperature of the first reaction module is 20~30°C, the plate temperature of the second reaction module is 40~60°C, and the plate temperature of the third reaction module is 60~80°C.

7. The preparation method according to claim 1, characterized in that: The residence time in the microchannel reactor is 5 to 30 min.

8. The preparation method according to claim 1, characterized in that: In step S2, the sodium source includes one or more of sodium carbonate, sodium hydroxide, sodium bicarbonate, sodium sulfate, and sodium sulfite; The aluminum source includes one or more of anhydrous aluminum chloride, aluminum sulfate 18-hydrate, aluminum hydroxide, and aluminum chloride hexahydrate; The molar ratio of the diisobutylphosphine, the oxidant, the sodium source and the aluminum source is 1:0.8-1.0:1.0-1.2:0.1-0.

3.

9. The preparation method according to claim 1, characterized in that: The temperature in the pipe reactor is 80~100 ℃.

10. The preparation method according to claim 1, characterized in that: The solvent for washing the filter cake is one or more of deionized water, methanol, ethanol, dichloromethane and ethyl acetate.

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