Synthesis method of DIPPN prepared based on propionitrile

Abstract

The invention relates to the technical field of organic chemical synthesis, and particularly discloses a DIPPN synthesis method based on propionitrile, and the DIPPN synthesis method based on propionitrile comprises the following steps: reacting acrylonitrile with hydrogen under the action of a magnetic core-shell bimetallic catalyst, and regenerating the catalyst by adopting supercritical CO2 to obtain DIPPN; high-purity propionitrile is obtained through gas-liquid separation and molecular sieve adsorption purification; then adding a premix of isopropyl bromide and ethyl lactate into a system containing propionitrile, sodium amide and tea saponin for reaction in an inert atmosphere, electrolyzing sodium hydroxide and bromine gas in a regenerated water phase after quenching and layering, and performing reduced pressure distillation and ultrasonic-assisted cooling crystallization on an organic phase to obtain a high-purity DIPPN solid; through supercritical CO2 regeneration of the catalyst, cyclic utilization of reaction byproducts and an ultrasonic-assisted crystallization process, the reaction efficiency, the product purity and the like are remarkably improved, and the obtained DIPPN is suitable for the fields of medicines, materials and the like.

Description

Technical Field

[0001] This application relates to the field of chemical pharmaceutical raw materials and formulation manufacturing technology, specifically a method for synthesizing DIPPN based on propionitrile. Background Technology

[0002] Propanonitrile is an important chemical raw material and formulation with wide applications in pharmaceuticals, pesticides, and specialty materials, especially as a key raw material in the synthesis of 2,2-diisopropylpropionitrile (DIPPN). However, existing propionitrile production processes suffer from significant bottlenecks: currently, industrial production mainly employs the high-pressure hydrogenation method of acrylonitrile, requiring reaction pressures typically maintained above 10 MPa. This not only places stringent demands on equipment pressure resistance but also poses significant safety hazards. These high-pressure operating conditions mean that only a handful of companies worldwide possess the production capacity, resulting in severely limited propionitrile supply, persistently high raw material prices, and directly impacting the economic viability of downstream products.

[0003] In the field of DIPPN synthesis, existing technologies mainly fall into two categories: the first is the sulfonate alkylation method, which requires expensive sulfonate reagents and produces a large amount of sulfonate byproducts after the reaction. Subsequent processing requires multiple extractions and washings, resulting in a complex process and high costs for waste treatment. The second is the sodium amide direct alkylation method, although the reaction route is simpler, it is entirely dependent on purchased propionitrile raw materials, making production costs directly subject to the market supply and price fluctuations of propionitrile. More importantly, the existing propionitrile production process and DIPPN synthesis steps are disconnected, failing to form a synergistic and optimized technical system, leading to high overall energy consumption and low efficiency.

[0004] In summary, propionitrile preparation and DIPPN synthesis face industry challenges such as limited raw material supply, complex processes, numerous byproducts, lack of green efficiency, and fragmented technologies. Based on the above, this application provides a DIPPN synthesis method based on propionitrile preparation. Summary of the Invention

[0005] To avoid the safety risks of traditional high-pressure hydrogenation processes, and to develop a new method for the efficient preparation of propionitrile under mild conditions and subsequent DIPPN synthesis, this application provides a DIPPN synthesis method based on propionitrile preparation.

[0006] In a first aspect, this application provides a method for synthesizing DIPPN based on propionitrile, employing the following technical solution:

[0007] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0008] S1. Acrylonitrile is reacted with hydrogen under the action of a catalyst. The catalyst is regenerated by supercritical CO2 during the process. After the reaction, crude acrylonitrile is obtained by gas-liquid separation.

[0009] S2. Crude propionitrile is adsorbed by molecular sieve to remove unreacted acrylonitrile, and then purified by secondary condensation to obtain propionitrile with a purity ≥99.9%.

[0010] S3. Under an inert atmosphere, the premix obtained by mixing isopropyl bromide and ethyl lactate is added to a reaction system containing propionitrile, sodium amino acid and tea saponin, and the reaction is kept at a constant temperature to obtain a reaction mixture.

[0011] S4. Add deionized water to the reaction mixture to quench the separation and obtain an aqueous phase and an organic phase. Electrolyze the aqueous phase to regenerate it. The resulting sodium hydroxide is used for the preparation of sodium amino acid, and bromine gas is used for the synthesis of isopropyl bromide.

[0012] S5. The organic phase is distilled under reduced pressure to recover the solvent and obtain the residue. The residue is then added to n-heptane and cooled by ultrasonication to crystallize and obtain DIPPN solid.

[0013] Preferably, the reaction conditions in step S1 are as follows: the molar ratio of acrylonitrile to hydrogen is 1:1.8-2.0, the mass ratio of acrylonitrile to catalyst is 100:3-5, the temperature is 80-120℃, the pressure is 1-3 MPa, and the reaction time is 8-10h; the regeneration conditions are as follows: the mass ratio of CO2 to catalyst is 30-50:1, the regeneration time is 30-40min, and regeneration is performed once every 2-3 hours of reaction; the gas-liquid separation conditions are as follows: condensation membrane separation technology is used, and the condensation temperature is -10-5℃.

[0014] Preferably, the catalyst in step S1 is a magnetic core-shell bimetallic catalyst, which is prepared by dissolving ferric chloride hexahydrate and ferrous chloride tetrahydrate in deionized water, adding salmon sperm DNA, reacting with ammonia under nitrogen protection, and magnetically separating to obtain iron oxide particles; dispersing iron oxide in an ethanol-water mixed solvent, adding glucose solution and ammonia, reacting at room temperature, and then magnetically separating to obtain the core-shell material; impregnating the core-shell material in a mixed solution of palladium chloride and cobalt nitrate, ultrasonically adsorbing, and then reducing with tannic acid to obtain the magnetic core-shell bimetallic catalyst.

[0015] Preferably, the preparation method of the magnetic core-shell bimetallic catalyst includes the following steps:

[0016] A1. Dissolve ferric chloride hexahydrate and ferrous chloride tetrahydrate in deionized water at a molar ratio of 1.5-2.5:1 to prepare a 0.4-0.6 mol / L iron salt solution. Add 0.1-0.3 wt% salmon sperm DNA to the iron salt solution. Under nitrogen protection, add ammonia to adjust the pH to 10-11. React at 55-65℃ for 0.5-1.5 h. Collect the black precipitate by magnetic separation, wash with deionized water 2-4 times, and vacuum dry at 50-60℃ to obtain iron oxide particles.

[0017] A2. Mix ferric oxide particles with an ethanol-water mixed solvent at a volume ratio of 0.04-0.06:1, with an ethanol to water volume ratio of 3-4:1. Then add 8-10 wt% glucose solution (with a mass ratio of 1:2-3 to ferric oxide) and ammonia (with a molar ratio of 20-30:1 to glucose solution). Stir the mixture at 400-500 rpm for 5-7 hours. After magnetic separation, wash with deionized water 2-4 times and vacuum dry at 75-85℃ to obtain the core-shell material.

[0018] A3. The core-shell material is immersed in a mixed solution of palladium chloride and cobalt nitrate with a molar ratio of 1:0.8-1.2 and a mass ratio of core-shell material to mixed solution of 1:4-6. After ultrasonic treatment at 200-300W for 1-2 hours, it is placed in an ice-water bath. A 3-5wt% tannic acid solution with a molar ratio of 4-6:1 to metal ions is added to the mixed solution. The mixture is reduced under a nitrogen atmosphere for 1.5-2.5 hours. After magnetic separation, it is washed 2-4 times with deionized water and dried under vacuum at 50-60℃ to obtain a magnetic core-shell bimetallic catalyst.

[0019] Preferably, in step S2, the molecular sieve is a 3Å molecular sieve with an adsorption temperature of 20-40℃ and an adsorption pressure of 0.1-0.5MPa; the first-stage condensation temperature is -5-5℃, and the second-stage condensation temperature is -15-10℃.

[0020] Preferably, in step S3, the inert atmosphere is nitrogen; the volume ratio of isopropyl bromide to ethyl lactate is 1:2-3; the volume ratio of propionitrile, sodium amino acid and tea saponin is 1:0.2-0.3:0.06-0.1; the volume ratio of premix to reaction system is 2-2.4:1; the reaction temperature is 40-60℃; and the reaction time is 4-6h.

[0021] Preferably, in step S4, the electrolytic regeneration uses an ion-exchange membrane electrolyzer, and the electrolysis conditions are: current density 100-300 A / m 2 The voltage is 3-6V and the electrolysis temperature is 30-60℃. The concentration of sodium hydroxide obtained is 20-30wt%. Sodium hydroxide is reacted with liquid ammonia to prepare sodium amino. The obtained bromine gas is condensed and liquefied to obtain liquid bromine. Liquid bromine is reacted with isopropanol at 40-60℃ to synthesize isopropyl bromide.

[0022] Preferably, the conditions for vacuum distillation in step S5 are: pressure -0.10 to 0.08 MPa, temperature 40 to 60°C; and the conditions for ultrasonic-assisted cooling crystallization are: mass ratio of n-heptane to residue of 3-5:1, ultrasonic power of 100-300 W, frequency of 20-40 kHz, cooling rate of 1-2°C / min, and cooling to -10 to 0°C for crystallization for 2-4 hours.

[0023] Secondly, this application provides a DIPPN synthesis method based on propionitrile preparation to obtain DIPPN.

[0024] Preferably, the DIPPN has a purity ≥99.6%, an isopropyl monosubstituted product content ≤0.2%, a melting point of 48.5-49.5℃, and a bulk density of 0.48-0.52 g / cm³. 3 .

[0025] In summary, this application has the following beneficial effects:

[0026] (1) By adopting mild reaction conditions (the reaction pressure is reduced from 5-10 MPa to 1-3 MPa compared with the traditional high-pressure hydrogenation process), combined with the efficient catalytic effect of the magnetic core-shell bimetallic catalyst, the efficient hydrogenation of acrylonitrile to propionitrile can be achieved at a temperature of 80-120℃, which greatly reduces the safety risk of the process and improves the controllability of the reaction.

[0027] (2) The design of supercritical CO2 regeneration catalyst, which is regenerated every 2-3 hours, can maintain the high activity of the catalyst and avoid the production interruption caused by traditional offline regeneration, significantly improving the continuity of production and catalyst life and reducing the cost of catalyst replacement.

[0028] (3) Magnetic core-shell bimetallic catalysts have the following advantages: First, the core-shell structure constructed by biological template regulation and carbonization process greatly increases the specific surface area, providing more anchoring sites for the metal active center; Second, the bimetallic nanoparticles supported by the green reduction method exhibit a unique electronic synergistic effect, which significantly improves hydrogenation activity and selectivity, and can achieve excellent conversion rate and selectivity under mild conditions; Third, the catalyst has strong magnetism, and efficient solid-liquid separation can be quickly achieved with the help of a simple external magnetic field, which saves a lot of energy compared with traditional methods.

[0029] (4) High-purity propionitrile was obtained by using a purification technology that combines molecular sieve adsorption and two-stage condensation, which solved the problems of high energy consumption and low purity of traditional distillation method. At the same time, hydrogen was efficiently recovered and utilized through gas membrane separation technology.

[0030] (5) In the DIPPN synthesis step, tea saponin is introduced as a phase transfer catalyst to promote the reaction of isopropyl bromide and propionitrile in the sodium amino system, which significantly improves the selectivity of the target product. With the optimized volume ratio (propionitrile: sodium amino: tea saponin = 1:0.2-0.3:0.06-0.1), the reaction time is shortened to 4-6 h, the product purity is increased to more than 99.6%, and the content of monosubstituted byproducts is controlled below 0.2%, which is significantly better than the 8-10 h reaction time and 95% purity of the traditional process.

[0031] (6) The use of tea saponin to replace the traditional phase transfer catalyst improves biodegradability. The ecotoxicity of the ethyl lactate solvent system is reduced compared to the traditional methyl tert-butyl ether system. Combined with the green reduction process of tannic acid, the VOC emissions of the whole process are reduced. An innovative closed-loop resource recycling system is constructed. Sodium hydroxide and bromine are regenerated by electrolysis of the aqueous phase and used for sodium amino preparation and isopropyl bromide synthesis, respectively. This achieves 100% recycling of key raw materials, reduces the amount of waste, and makes the whole process green, safe and low-pollution.

[0032] (7) By using ultrasonic-assisted cooling crystallization technology, high-quality DIPPN crystals with high bulk density are obtained by precisely controlling ultrasonic parameters and cooling rate, improving product flowability and meeting the strict requirements of pharmaceutical intermediates for physical properties.

[0033] (8) The entire process achieves seamless connection from propionitrile preparation to DIPPN synthesis through parameter optimization of each step (such as the magnetic core-shell structure design of the catalyst to facilitate magnetic separation and recovery, and condensation membrane separation technology to improve separation efficiency). The production process is continuous and stable, easy to scale up industrially, and has good economic and environmental benefits. Detailed Implementation

[0034] The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0035] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0036] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available products.

[0037] Preparation Examples 1-3 and Comparative Preparation Examples 1-3 provide methods for preparing magnetic core-shell bimetallic catalysts.

[0038] Preparation Example 1

[0039] Magnetic core-shell bimetallic catalysts are prepared by the following methods:

[0040] A1. Ferric chloride hexahydrate and ferrous chloride tetrahydrate were dissolved in deionized water at a molar ratio of 1.5:1 to prepare a 0.4 mol / L iron salt solution. 0.1 wt% salmon sperm DNA was added to the iron salt solution. Under nitrogen protection, ammonia was added to adjust the pH to 10. The reaction was carried out at 55℃ for 0.5 h. The black precipitate was collected by magnetic separation, washed twice with deionized water, and dried under vacuum at 50℃ to obtain iron oxide particles.

[0041] A2. Iron oxide particles were mixed with an ethanol-water mixed solvent at a volume ratio of 0.04:1 and an ethanol-water volume ratio of 3:1. Then, 8 wt% glucose solution (with a mass ratio of 1:2 to iron oxide) and ammonia water (with a molar ratio of 20:1 to glucose solution) were added. The mixture was stirred at 400 rpm for 5 h. After magnetic separation, the mixture was washed twice with deionized water and dried under vacuum at 75 °C to obtain the core-shell material.

[0042] A3. The core-shell material was immersed in a mixed solution of palladium chloride and cobalt nitrate with a molar ratio of 1:0.8 and a mass ratio of core-shell material to mixed solution of 1:4. After ultrasonic treatment at 200W for 1 hour, it was placed in an ice-water bath. A 3wt% tannic acid solution with a molar ratio of 4:1 to metal ions was added to the mixed solution. The mixture was reduced under a nitrogen atmosphere for 1.5 hours. After magnetic separation, it was washed twice with deionized water and dried under vacuum at 50℃ to obtain a magnetic core-shell bimetallic catalyst.

[0043] Preparation Example 2

[0044] Magnetic core-shell bimetallic catalysts are prepared by the following methods:

[0045] A1. Ferric chloride hexahydrate and ferrous chloride tetrahydrate were dissolved in deionized water at a molar ratio of 2:1 to prepare a 0.5 mol / L iron salt solution. 0.2 wt% salmon sperm DNA was added to the iron salt solution. Under nitrogen protection, ammonia was added to adjust the pH to 10.5. The reaction was carried out at 60℃ for 1 h. The black precipitate was collected by magnetic separation, washed three times with deionized water, and dried under vacuum at 55℃ to obtain iron oxide particles.

[0046] A2. Iron oxide particles were mixed with an ethanol-water mixed solvent at a volume ratio of 0.05:1 and an ethanol-water volume ratio of 3.5:1. Then, 9 wt% glucose solution (with a mass ratio of 1:2.5 to iron oxide) and ammonia water (with a molar ratio of 25:1 to glucose solution) were added. The mixture was stirred at 450 rpm for 6 hours. After magnetic separation, the mixture was washed three times with deionized water and dried under vacuum at 80℃ to obtain the core-shell material.

[0047] A3. The core-shell material was immersed in a mixed solution of palladium chloride and cobalt nitrate with a molar ratio of 1:1 and a mass ratio of core-shell material to mixed solution of 1:5. After ultrasonic treatment at 250W for 1.5h, it was placed in an ice-water bath. A 4wt% tannic acid solution with a molar ratio of 5:1 to metal ions was added to the mixed solution. The mixture was reduced under a nitrogen atmosphere for 2h. After magnetic separation, it was washed three times with deionized water and dried under vacuum at 55℃ to obtain a magnetic core-shell bimetallic catalyst.

[0048] Preparation Example 3

[0049] Magnetic core-shell bimetallic catalysts are prepared by the following methods:

[0050] A1. Ferric chloride hexahydrate and ferrous chloride tetrahydrate were dissolved in deionized water at a molar ratio of 2.5:1 to prepare a 0.6 mol / L iron salt solution. 0.3 wt% salmon sperm DNA was added to the iron salt solution. Under nitrogen protection, ammonia was added to adjust the pH to 11. The reaction was carried out at 65°C for 1.5 h. The black precipitate was collected by magnetic separation, washed 4 times with deionized water, and dried under vacuum at 60°C to obtain iron oxide particles.

[0051] A2. Iron oxide particles were mixed with an ethanol-water mixture at a volume ratio of 0.06:1 and an ethanol-water volume ratio of 4:1. Then, 10wt% glucose solution (with a mass ratio of 1:3 to iron oxide) and ammonia (with a molar ratio of 30:1 to glucose solution) were added. The mixture was stirred at 500 rpm for 7 hours. After magnetic separation, the mixture was washed four times with deionized water and dried under vacuum at 85℃ to obtain the core-shell material.

[0052] A3. The core-shell material was immersed in a mixed solution of palladium chloride and cobalt nitrate with a molar ratio of 1:1.2 and a mass ratio of core-shell material to mixed solution of 1:6. After ultrasonic treatment at 300W for 2 hours, it was placed in an ice-water bath. A 5wt% tannic acid solution with a molar ratio of 6:1 to metal ions was added to the mixed solution. The mixture was reduced under a nitrogen atmosphere for 2.5 hours. After magnetic separation, it was washed four times with deionized water and dried under vacuum at 60℃ to obtain a magnetic core-shell bimetallic catalyst.

[0053] Comparative Preparation Example 1

[0054] Magnetic core-shell bimetallic catalysts are prepared by the following methods:

[0055] A1. Ferric chloride hexahydrate and ferrous chloride tetrahydrate were dissolved in deionized water at a molar ratio of 2:1 to prepare a 0.5 mol / L iron salt solution. Under nitrogen protection, ammonia was added to adjust the pH to 10.5. The reaction was carried out at 60℃ for 1 h. The black precipitate was collected by magnetic separation, washed three times with deionized water, and dried under vacuum at 55℃ to obtain iron oxide particles.

[0056] A2. Iron oxide particles were mixed with an ethanol-water mixed solvent at a volume ratio of 0.05:1 and an ethanol-water volume ratio of 3.5:1. Then, 9 wt% glucose solution (with a mass ratio of 1:2.5 to iron oxide) and ammonia water (with a molar ratio of 25:1 to glucose solution) were added. The mixture was stirred at 450 rpm for 6 hours. After magnetic separation, the mixture was washed three times with deionized water and dried under vacuum at 80℃ to obtain the core-shell material.

[0057] A3. The core-shell material was immersed in a mixed solution of palladium chloride and cobalt nitrate with a molar ratio of 1:1 and a mass ratio of core-shell material to mixed solution of 1:5. After ultrasonic treatment at 250W for 1.5h, it was placed in an ice-water bath. A 4wt% tannic acid solution with a molar ratio of 5:1 to metal ions was added to the mixed solution. The mixture was reduced under a nitrogen atmosphere for 2h. After magnetic separation, it was washed three times with deionized water and dried under vacuum at 55℃ to obtain a magnetic core-shell bimetallic catalyst.

[0058] Comparative Preparation Example 2

[0059] Magnetic core-shell bimetallic catalysts are prepared by the following methods:

[0060] A1. Ferric chloride hexahydrate and ferrous chloride tetrahydrate were dissolved in deionized water at a molar ratio of 2:1 to prepare a 0.5 mol / L iron salt solution. 0.2 wt% chitosan was added to the iron salt solution. Under nitrogen protection, ammonia was added to adjust the pH to 10.5. The reaction was carried out at 60℃ for 1 h. The black precipitate was collected by magnetic separation, washed three times with deionized water, and dried under vacuum at 55℃ to obtain iron oxide particles.

[0061] A2. Iron oxide particles were mixed with an ethanol-water mixed solvent at a volume ratio of 0.05:1 and an ethanol-water volume ratio of 3.5:1. Then, 9 wt% glucose solution (with a mass ratio of 1:2.5 to iron oxide) and ammonia water (with a molar ratio of 25:1 to glucose solution) were added. The mixture was stirred at 450 rpm for 6 hours. After magnetic separation, the mixture was washed three times with deionized water and dried under vacuum at 80℃ to obtain the core-shell material.

[0062] A3. The core-shell material was immersed in a mixed solution of palladium chloride and cobalt nitrate with a molar ratio of 1:1 and a mass ratio of core-shell material to mixed solution of 1:5. After ultrasonic treatment at 250W for 1.5h, it was placed in an ice-water bath. A 4wt% tannic acid solution with a molar ratio of 5:1 to metal ions was added to the mixed solution. The mixture was reduced under a nitrogen atmosphere for 2h. After magnetic separation, it was washed three times with deionized water and dried under vacuum at 55℃ to obtain a magnetic core-shell bimetallic catalyst.

[0063] Comparative preparation example 3

[0064] Magnetic core-shell bimetallic catalysts are prepared by the following methods:

[0065] A1. Ferric chloride hexahydrate and ferrous chloride tetrahydrate were dissolved in deionized water at a molar ratio of 2:1 to prepare a 0.5 mol / L iron salt solution. 0.2 wt% salmon sperm DNA was added to the iron salt solution. Under nitrogen protection, ammonia was added to adjust the pH to 10.5. The reaction was carried out at 60℃ for 1 h. The black precipitate was collected by magnetic separation, washed three times with deionized water, and dried under vacuum at 55℃ to obtain iron oxide particles.

[0066] A2. Mix iron oxide particles with an ethanol-water mixed solvent at a volume ratio of 0.05:1 and an ethanol-water volume ratio of 3.5:1. Then add tetraethyl orthosilicate (mass ratio of 1:2.5 to iron oxide) and ammonia (molar ratio of 25:1 to tetraethyl orthosilicate). Stir the mixture at 450 rpm for 6 hours. After magnetic separation, wash the mixture three times with deionized water and dry it under vacuum at 80°C to obtain the core-shell material.

[0067] A3. The core-shell material was immersed in a mixed solution of palladium chloride and cobalt nitrate with a molar ratio of 1:1 and a mass ratio of core-shell material to mixed solution of 1:5. After ultrasonic treatment at 250W for 1.5h, it was placed in an ice-water bath. A 4wt% tannic acid solution with a molar ratio of 5:1 to metal ions was added to the mixed solution. The mixture was reduced under a nitrogen atmosphere for 2h. After magnetic separation, it was washed three times with deionized water and dried under vacuum at 55℃ to obtain a magnetic core-shell bimetallic catalyst.

[0068] Examples 1-3 provide a method for synthesizing DIPPN based on propionitrile.

[0069] Example 1

[0070] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0071] S1. Acrylonitrile and hydrogen were reacted in a molar ratio of 1:1.8 under the action of the magnetic core-shell bimetallic catalyst prepared in Preparation Example 1, with an acrylonitrile to catalyst mass ratio of 100:3. The reaction conditions were 80°C, 1 MPa, and 8 h. During the reaction, the catalyst was regenerated with supercritical CO2 every 2 h, with a CO2 to catalyst mass ratio of 30:1 and a regeneration time of 30 min. After the reaction, gas-liquid separation was performed using condensation membrane separation technology at a condensation temperature of -10°C to obtain crude acrylonitrile.

[0072] S2. Crude propionitrile is passed through a 3Å molecular sieve at an adsorption temperature of 20℃ and an adsorption pressure of 0.1MPa to remove unreacted acrylonitrile. Then, it is purified by a first-stage condensation at a condensation temperature of -5℃ and a second-stage condensation at a condensation temperature of -15℃ to obtain propionitrile with a purity of 99.9%.

[0073] S3. Under nitrogen protection, a premix of isopropyl bromide and ethyl lactate in a volume ratio of 1:2 was added to a reaction system containing propionitrile, sodium amino acid and tea saponin in a volume ratio of 1:0.2:0.06. The volume ratio of the premix to the reaction system was 2:1. The reaction was kept at 40°C for 4 hours to obtain the reaction mixture.

[0074] S4. Add deionized water to the reaction mixture to quench the reaction, resulting in a separation of aqueous and organic phases. Regenerate the aqueous phase using an ion-exchange membrane electrolyzer under the following conditions: current density 100 A / m³. 2At a voltage of 3V and an electrolysis temperature of 30℃, 20wt% sodium hydroxide (used for the preparation of sodium amino) and bromine gas (which, after condensation and liquefaction, reacts with isopropanol at 40℃ to synthesize isopropyl bromide) are obtained.

[0075] S5. The organic phase was subjected to vacuum distillation at -0.10 MPa and 40 °C to recover the solvent and obtain the residue. The residue was mixed with n-heptane at a mass ratio of 3:1, ultrasonicated at 100 W and 20 kHz, cooled to -10 °C at 1 °C / min, and crystallized for 2 h to obtain DIPPN solid.

[0076] Example 2

[0077] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0078] S1. Acrylonitrile and hydrogen were reacted in a molar ratio of 1:1.9 under the action of the magnetic core-shell bimetallic catalyst prepared in Preparation Example 2, with an acrylonitrile to catalyst mass ratio of 100:4. The reaction conditions were 100°C, 2 MPa, and 9 h. During the reaction, the catalyst was regenerated with supercritical CO2 every 2.5 h, with a CO2 to catalyst mass ratio of 40:1 and a regeneration time of 35 min. After the reaction, gas-liquid separation was performed using condensation membrane separation technology at a condensation temperature of -2.5°C to obtain crude propionitrile.

[0079] S2. Crude propionitrile is passed through a 3Å molecular sieve at an adsorption temperature of 30℃ and an adsorption pressure of 0.3MPa to remove unreacted acrylonitrile. Then, it is purified by first-stage condensation at a condensation temperature of 0℃ and second-stage condensation at a condensation temperature of -2.5℃ to obtain propionitrile with a purity of 99.9%.

[0080] S3. Under nitrogen protection, a premix of isopropyl bromide and ethyl lactate in a volume ratio of 1:2.5 was added to a reaction system containing propionitrile, sodium amino acid and tea saponin in a volume ratio of 1:0.25:0.08. The volume ratio of the premix to the reaction system was 2.2:1. The reaction was kept at 50°C for 5 hours to obtain the reaction mixture.

[0081] S4. Add deionized water to the reaction mixture to quench the reaction, resulting in a separation of aqueous and organic phases. Regenerate the aqueous phase using an ion-exchange membrane electrolyzer under the following conditions: current density 200 A / m³. 2 At a voltage of 4.5V and an electrolysis temperature of 45℃, 25wt% sodium hydroxide (used for the preparation of sodium amino) and bromine gas (which, after condensation and liquefaction, reacts with isopropanol at 50℃ to synthesize isopropyl bromide) were obtained.

[0082] S5. The organic phase was distilled under reduced pressure at -0.09 MPa and 50 °C to recover the solvent and obtain the residue. The residue was mixed with n-heptane at a mass ratio of 4:1, ultrasonicated at 200 W and 30 kHz, cooled to -5 °C at 1.5 °C / min, and crystallized for 3 h to obtain DIPPN solid.

[0083] Example 3

[0084] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0085] S1. Acrylonitrile and hydrogen were reacted in a molar ratio of 1:2.0 under the action of the magnetic core-shell bimetallic catalyst prepared in Preparation Example 3, with an acrylonitrile to catalyst mass ratio of 100:5. The reaction conditions were 120°C, 3 MPa, and 10 h. During the reaction, the catalyst was regenerated with supercritical CO2 every 3 h, with a CO2 to catalyst mass ratio of 50:1 and a regeneration time of 40 min. After the reaction, gas-liquid separation was performed using condensation membrane separation technology at a condensation temperature of 5°C to obtain crude acrylonitrile.

[0086] S2. Crude propionitrile is passed through a 3Å molecular sieve at an adsorption temperature of 40℃ and an adsorption pressure of 0.5MPa to remove unreacted acrylonitrile. Then, it is purified by a first-stage condensation at a condensation temperature of 5℃ and a second-stage condensation at a condensation temperature of -10℃ to obtain propionitrile with a purity of 99.9%.

[0087] S3. Under nitrogen protection, a premix of isopropyl bromide and ethyl lactate in a volume ratio of 1:3 was added to a reaction system containing propionitrile, sodium amino acid and tea saponin in a volume ratio of 1:0.3:0.1. The volume ratio of the premix to the reaction system was 2.4:1. The reaction was kept at 60°C for 6 hours to obtain the reaction mixture.

[0088] S4. Add deionized water to the reaction mixture to quench the reaction, resulting in a separation of aqueous and organic phases. Regenerate the aqueous phase using an ion-exchange membrane electrolyzer under the following conditions: current density 300 A / m³. 2 At a voltage of 6 V and an electrolysis temperature of 60 °C, 30 wt% sodium hydroxide (used for the preparation of sodium amino) and bromine gas (which, after condensation and liquefaction, reacts with isopropanol at 60 °C to synthesize isopropyl bromide) are obtained.

[0089] S5. The organic phase was subjected to vacuum distillation at -0.08 MPa and 60 °C to recover the solvent and obtain the residue. The residue was mixed with n-heptane at a mass ratio of 5:1, ultrasonicated at 300 W and 40 kHz, cooled to 0 °C at 2 °C / min, and crystallized for 4 h to obtain DIPPN solid.

[0090] Comparative Example 1

[0091] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0092] S1. Acrylonitrile and hydrogen were reacted in Raney Ni at a molar ratio of 1:1.9 (mass ratio of acrylonitrile to Raney Ni 100:4) under the following conditions: temperature 100℃, pressure 2MPa, and time 9h. During the reaction, Raney Ni was regenerated with supercritical CO2 every 2.5h (mass ratio of CO2 to Raney Ni 40:1) for 35min. After the reaction, gas-liquid separation was performed using a condensation membrane separation technique at a condensation temperature of -2.5℃ to obtain crude acrylonitrile.

[0093] S2. Crude propionitrile is passed through a 3Å molecular sieve at an adsorption temperature of 30℃ and an adsorption pressure of 0.3MPa to remove unreacted acrylonitrile. Then, it is purified by first-stage condensation at a condensation temperature of 0℃ and second-stage condensation at a condensation temperature of -2.5℃ to obtain propionitrile with a purity of 99.9%.

[0094] S3. Under nitrogen protection, a premix of isopropyl bromide and ethyl lactate in a volume ratio of 1:2.5 was added to a reaction system containing propionitrile, sodium amino acid and tea saponin in a volume ratio of 1:0.25:0.08. The volume ratio of the premix to the reaction system was 2.2:1. The reaction was kept at 50°C for 5 hours to obtain the reaction mixture.

[0095] S4. Add deionized water to the reaction mixture to quench the reaction, resulting in a separation of aqueous and organic phases. Regenerate the aqueous phase using an ion-exchange membrane electrolyzer under the following conditions: current density 200 A / m³. 2 At a voltage of 4.5V and an electrolysis temperature of 45℃, 25wt% sodium hydroxide (used for the preparation of sodium amino) and bromine gas (which, after condensation and liquefaction, reacts with isopropanol at 50℃ to synthesize isopropyl bromide) were obtained.

[0096] S5. The organic phase was distilled under reduced pressure at -0.09 MPa and 50 °C to recover the solvent and obtain the residue. The residue was mixed with n-heptane at a mass ratio of 4:1, ultrasonicated at 200 W and 30 kHz, cooled to -5 °C at 1.5 °C / min, and crystallized for 3 h to obtain DIPPN solid.

[0097] Comparative Example 2

[0098] Same as Example 2, except that the magnetic core-shell bimetallic catalyst was prepared in Comparative Preparation Example 1.

[0099] Comparative Example 3

[0100] Same as Example 2, except that the magnetic core-shell bimetallic catalyst was prepared in Comparative Preparation Example 2.

[0101] Comparative Example 4

[0102] Same as Example 2, except that the magnetic core-shell bimetallic catalyst was prepared in Comparative Preparation Example 3.

[0103] Comparative Example 5

[0104] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0105] S1. Acrylonitrile and hydrogen were reacted in a molar ratio of 1:1.9 under the action of a magnetic core-shell bimetallic catalyst. The mass ratio of acrylonitrile to catalyst was 100:4. The reaction conditions were 100℃, 2MPa, and 9h. After the reaction, gas-liquid separation was carried out using condensation membrane separation technology at a condensation temperature of -2.5℃ to obtain crude acrylonitrile.

[0106] S2. Crude propionitrile is passed through a 3Å molecular sieve at an adsorption temperature of 30℃ and an adsorption pressure of 0.3MPa to remove unreacted acrylonitrile. Then, it is purified by first-stage condensation at a condensation temperature of 0℃ and second-stage condensation at a condensation temperature of -2.5℃ to obtain propionitrile with a purity of 99.9%.

[0107] S3. Under nitrogen protection, a premix of isopropyl bromide and ethyl lactate in a volume ratio of 1:2.5 was added to a reaction system containing propionitrile, sodium amino acid and tea saponin in a volume ratio of 1:0.25:0.08. The volume ratio of the premix to the reaction system was 2.2:1. The reaction was kept at 50°C for 5 hours to obtain the reaction mixture.

[0108] S4. Add deionized water to the reaction mixture to quench the reaction, resulting in a separation of aqueous and organic phases. Regenerate the aqueous phase using an ion-exchange membrane electrolyzer under the following conditions: current density 200 A / m³. 2 At a voltage of 4.5V and an electrolysis temperature of 45℃, 25wt% sodium hydroxide (used for the preparation of sodium amino) and bromine gas (which, after condensation and liquefaction, reacts with isopropanol at 50℃ to synthesize isopropyl bromide) were obtained.

[0109] S5. The organic phase was distilled under reduced pressure at -0.09 MPa and 50 °C to recover the solvent and obtain the residue. The residue was mixed with n-heptane at a mass ratio of 4:1, ultrasonicated at 200 W and 30 kHz, cooled to -5 °C at 1.5 °C / min, and crystallized for 3 h to obtain DIPPN solid.

[0110] Comparative Example 6

[0111] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0112] S1. Acrylonitrile and hydrogen were reacted in a molar ratio of 1:1.9 under the action of a magnetic core-shell bimetallic catalyst, with an acrylonitrile to catalyst mass ratio of 100:4. The reaction conditions were 100℃, 2MPa, and 9h. During the reaction, the catalyst was regenerated with supercritical CO2 every 2.5h, with a CO2 to catalyst mass ratio of 40:1 and a regeneration time of 35min. After the reaction, gas-liquid separation was performed using condensation membrane separation technology at a condensation temperature of -2.5℃ to obtain crude acrylonitrile.

[0113] S2. Crude propionitrile is passed through a 3Å molecular sieve at an adsorption temperature of 30℃ and an adsorption pressure of 0.3MPa to remove unreacted acrylonitrile. Then, it is purified by first-stage condensation at a condensation temperature of 0℃ and second-stage condensation at a condensation temperature of -2.5℃ to obtain propionitrile with a purity of 99.9%.

[0114] S3. Under nitrogen protection, a premix of isopropyl bromide and ethyl lactate in a volume ratio of 1:2.5 was added to a reaction system containing propionitrile and sodium amide in a volume ratio of 1:0.25. The volume ratio of the premix to the reaction system was 2.2:1. The reaction was carried out at 50°C for 5 hours to obtain the reaction mixture.

[0115] S4. Add deionized water to the reaction mixture to quench the reaction, resulting in a separation of aqueous and organic phases. Regenerate the aqueous phase using an ion-exchange membrane electrolyzer under the following conditions: current density 200 A / m³. 2 At a voltage of 4.5V and an electrolysis temperature of 45℃, 25wt% sodium hydroxide (used for the preparation of sodium amino) and bromine gas (which, after condensation and liquefaction, reacts with isopropanol at 50℃ to synthesize isopropyl bromide) were obtained.

[0116] S5. The organic phase was distilled under reduced pressure at -0.09 MPa and 50 °C to recover the solvent and obtain the residue. The residue was mixed with n-heptane at a mass ratio of 4:1, ultrasonicated at 200 W and 30 kHz, cooled to -5 °C at 1.5 °C / min, and crystallized for 3 h to obtain DIPPN solid.

[0117] Comparative Example 7

[0118] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0119] S1. Acrylonitrile and hydrogen were reacted in a molar ratio of 1:1.9 under the action of a magnetic core-shell bimetallic catalyst, with an acrylonitrile to catalyst mass ratio of 100:4. The reaction conditions were 100℃, 2MPa, and 9h. During the reaction, the catalyst was regenerated with supercritical CO2 every 2.5h, with a CO2 to catalyst mass ratio of 40:1 and a regeneration time of 35min. After the reaction, gas-liquid separation was performed using condensation membrane separation technology at a condensation temperature of -2.5℃ to obtain crude acrylonitrile.

[0120] S2. Crude propionitrile is passed through a 3Å molecular sieve at an adsorption temperature of 30℃ and an adsorption pressure of 0.3MPa to remove unreacted acrylonitrile. Then, it is purified by first-stage condensation at a condensation temperature of 0℃ and second-stage condensation at a condensation temperature of -2.5℃ to obtain propionitrile with a purity of 99.9%.

[0121] S3. Under nitrogen protection, a premix of isopropyl bromide and ethyl lactate in a volume ratio of 1:2.5 was added to a reaction system containing propionitrile, sodium amino acid and 18-crown ether-6 in a volume ratio of 1:0.25:0.08. The volume ratio of the premix to the reaction system was 2.2:1. The reaction was carried out at 50°C for 5 hours to obtain the reaction mixture.

[0122] S4. Add deionized water to the reaction mixture to quench the reaction, resulting in a separation of aqueous and organic phases. Regenerate the aqueous phase using an ion-exchange membrane electrolyzer under the following conditions: current density 200 A / m³. 2 At a voltage of 4.5V and an electrolysis temperature of 45℃, 25wt% sodium hydroxide (used for the preparation of sodium amino) and bromine gas (which, after condensation and liquefaction, reacts with isopropanol at 50℃ to synthesize isopropyl bromide) were obtained.

[0123] S5. The organic phase was distilled under reduced pressure at -0.09 MPa and 50 °C to recover the solvent and obtain the residue. The residue was mixed with n-heptane at a mass ratio of 4:1, ultrasonicated at 200 W and 30 kHz, cooled to -5 °C at 1.5 °C / min, and crystallized for 3 h to obtain DIPPN solid.

[0124] Comparative Example 8

[0125] A method for synthesizing DIPPN based on propionitrile includes the following steps:

[0126] S1. Acrylonitrile and hydrogen were reacted in a molar ratio of 1:1.9 under the action of a magnetic core-shell bimetallic catalyst, with an acrylonitrile to catalyst mass ratio of 100:4. The reaction conditions were 100℃, 2MPa, and 9h. During the reaction, the catalyst was regenerated with supercritical CO2 every 2.5h, with a CO2 to catalyst mass ratio of 40:1 and a regeneration time of 35min. After the reaction, gas-liquid separation was performed using condensation membrane separation technology at a condensation temperature of -2.5℃ to obtain crude acrylonitrile.

[0127] S2. Crude propionitrile is passed through a 3Å molecular sieve at an adsorption temperature of 30℃ and an adsorption pressure of 0.3MPa to remove unreacted acrylonitrile. Then, it is purified by first-stage condensation at a condensation temperature of 0℃ and second-stage condensation at a condensation temperature of -2.5℃ to obtain propionitrile with a purity of 99.9%.

[0128] S3. Under nitrogen protection, a premix of isopropyl bromide and ethyl lactate in a volume ratio of 1:2.5 was added to a reaction system containing propionitrile, sodium amino acid and tea saponin in a volume ratio of 1:0.25:0.08. The volume ratio of the premix to the reaction system was 2.2:1. The reaction was kept at 50°C for 5 hours to obtain the reaction mixture.

[0129] S4. Add deionized water to the reaction mixture to quench it, and separate the phases to obtain an aqueous phase and an organic phase;

[0130] S5. The organic phase was distilled under reduced pressure at -0.09 MPa and 50 °C to recover the solvent and obtain the residue. The residue was mixed with n-heptane at a mass ratio of 4:1, ultrasonicated at 200 W and 30 kHz, cooled to -5 °C at 1.5 °C / min, and crystallized for 3 h to obtain DIPPN solid.

[0131] Comparative experiment on the overall performance of the final product

[0132] To verify the differences in purity, impurity content, crystal characteristics, and environmental friendliness between the DIPPN final products prepared in Examples 1-3 and Comparative Examples 1-8 of this application, and to comprehensively evaluate the technical advantages, the test indicators and methods shown in Table 1 were set up.

[0133] Table 1 Test Indicators and Methods

[0134] Test Project Test methods Evaluation criteria Product purity HPLC Purity ≥ 99.6% Isopropyl monosubstituted products GC-MS Monosubstituted product content ≤0.2% Crystal packing density tap density meter <![CDATA[Bulk density 0.48 - 0.52 g / cm 3 > Solvent residue Headspace GC Total residues ≤100ppm Wastewater COD Potassium dichromate method COD ≤ 500mg / L Process carbon emissions Life cycle assessment <![CDATA[Carbon emissions ≤ 5 kg CO2eq / kg]]>

[0135] Examples 1-3 and Comparative Examples 1-8 all used the same batch of acrylonitrile, isopropyl bromide, hydrogen, and other raw materials, and were operated in reactors of the same specifications. The reactions, separations, and crystallizations were carried out according to the methods of each example and comparative example, and key parameters such as reaction time, temperature, and energy consumption were recorded. The DIPPN solids after crystallization from Examples 1-3 and Comparative Examples 1-8 were taken, pulverized through an 80-mesh sieve, and then packaged for testing. Purity and impurities were detected using HPLC and GC-MS according to the test methods in Table 1; bulk density was tested using a tap density meter; solvent residue was tested using headspace GC; COD of wastewater was determined using the potassium dichromate method; and total carbon emissions were calculated using an LCA model. The test results are shown in Table 2.

[0136] Table 2 Comparison of the overall performance of DIPPN final products

[0137] Test group purity(%) Monosubstituted products (%) Bulk density (g / cm³) Solvent residue (ppm) Wastewater COD (mg / L) <![CDATA[Carbon emissions (kg CO2eq / kg)]]> Example 1 99.7 0.18 0.50 45 180 3.0 Example 2 99.8 0.15 0.51 42 164 2.9 Example 3 99.6 0.20 0.49 43 172 3.3 Comparative Example 1 98.5 0.42 0.50 110 480 4.8 Comparative Example 2 99.0 0.33 0.49 52 201 3.4 Comparative Example 3 99.6 0.23 0.49 43 175 3.1 Comparative Example 4 99.2 0.24 0.50 45 188 3.3 Comparative Example 5 97.9 0.65 0.48 120 785 5.1 Comparative Example 6 99.1 0.29 0.50 61 188 3.2 Comparative Example 7 99.3 0.25 0.48 55 256 5.0 Comparative Example 8 99.6 0.17 0.50 42 1012 5.3

[0138] Based on the comprehensive performance data analysis of the DIPPN final products of Examples 1-3 and Comparative Examples 1-8 in Table 2, the following conclusions can be drawn:

[0139] Examples 1-3 employ the DIPPN synthesis method based on propionitrile provided in this application. Through optimization of key aspects such as catalyst, reaction conditions, purification process, and byproduct recycling, the product purity, reaction efficiency, and environmental performance are significantly improved. In contrast, Comparative Examples 1-8 involved modifications at a certain stage, leading to a decrease in overall performance, further validating the necessity of the technical features of this application.

[0140] Regarding catalysts, Examples 1-3 used magnetic core-shell bimetallic catalysts, whose core-shell structure and highly dispersed metal sites significantly improved hydrogenation efficiency and selectivity, resulting in product purity ≥99.6% and monosubstituted byproduct content ≤0.2%. In contrast, Comparative Example 1 used a traditional Raney Ni catalyst, which had poor selectivity, resulting in product purity of only 98.5% and monosubstituted byproduct content rising to 0.42%. Comparative Example 2 did not use salmon sperm DNA template, leading to an uneven catalyst structure, reduced dispersion of active sites, and a purity drop to 99.0%. Comparative Example 3 used chitosan instead of DNA template, and although the purity still reached 99.6%, the monosubstituted byproduct content was slightly higher (0.23%), indicating that DNA templates are more advantageous in optimizing the electronic structure of catalysts. Comparative Example 4 used tetraethyl orthosilicate instead of glucose carbonized shell, and due to the weak anchoring effect of the silicon shell on the metal active center, the catalytic efficiency decreased, and the purity dropped to 99.2%.

[0141] Regarding catalyst regeneration, Examples 1-3 employed supercritical CO2 online regeneration technology, which maintained the long-term high efficiency of the catalyst and ensured the continuous and stable reaction. However, Comparative Example 5 was not regenerated, and the catalyst gradually deactivated, resulting in incomplete reaction, a significant decrease in product purity to 97.9%, and a significant increase in solvent residue and wastewater COD.

[0142] Regarding the selection of phase transfer catalysts, Examples 1-3 introduced tea saponin, whose biodegradability and efficient catalytic effect shortened the reaction time to 4-6 hours, with a monosubstituted product content ≤0.2% and wastewater COD ≤180 mg / L; Comparative Example 6 did not use tea saponin, resulting in a decrease in reaction selectivity and an increase in monosubstituted product to 0.29%; Comparative Example 7 used traditional 18-crown ether-6 to replace tea saponin. Although the reaction could still proceed, due to its higher toxicity and slightly lower catalytic efficiency, the monosubstituted product content increased to 0.25%, and the wastewater COD increased to 256 mg / L.

[0143] Regarding the recycling of by-products, Examples 1-3 achieved closed-loop utilization of key raw materials by electrolyzing NaOH and Br2 in the aqueous phase, significantly reducing wastewater COD and carbon emissions; while Comparative Example 8 did not undergo electrolytic regeneration, resulting in wastewater COD rising to 1012 mg / L and carbon emissions increasing to 5.3 kg CO2eq / kg, demonstrating the importance of resource recycling for green production.

[0144] The above specific embodiments are merely explanations of this application and are not intended to limit this application. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for synthesizing DIPPN based on propionitrile, characterized in that, Includes the following steps: S1. Acrylonitrile is reacted with hydrogen under the action of a catalyst. The catalyst is regenerated by supercritical CO2 during the process. After the reaction, crude acrylonitrile is obtained by gas-liquid separation. S2. Crude propionitrile is adsorbed by molecular sieve to remove unreacted acrylonitrile, and then purified by secondary condensation to obtain propionitrile with a purity ≥99.9%. S3. Under an inert atmosphere, the premix obtained by mixing isopropyl bromide and ethyl lactate is added to a reaction system containing propionitrile, sodium amino acid and tea saponin, and the reaction is kept at a constant temperature to obtain a reaction mixture. S4. Add deionized water to the reaction mixture to quench the separation and obtain an aqueous phase and an organic phase. Electrolyze the aqueous phase to regenerate it. The resulting sodium hydroxide is used for the preparation of sodium amino acid, and bromine gas is used for the synthesis of isopropyl bromide. S5. The organic phase is distilled under reduced pressure to recover the solvent and obtain the residue. The residue is then added to n-heptane and cooled by ultrasonication to crystallize and obtain DIPPN solid.

2. The method for synthesizing DIPPN based on propionitrile according to claim 1, characterized in that, The reaction conditions in step S1 are as follows: the molar ratio of acrylonitrile to hydrogen is 1:1.8-2.0, the mass ratio of acrylonitrile to catalyst is 100:3-5, the temperature is 80-120℃, the pressure is 1-3MPa, and the reaction time is 8-10h; the regeneration conditions are as follows: the mass ratio of CO2 to catalyst is 30-50:1, the regeneration time is 30-40min, and regeneration is performed once every 2-3h of reaction; the gas-liquid separation conditions are as follows: condensation membrane separation technology is used, and the condensation temperature is -10-5℃.

3. The method for synthesizing DIPPN based on propionitrile according to claim 1, characterized in that, The catalyst in step S1 is a magnetic core-shell bimetallic catalyst, which is prepared as follows: ferric chloride hexahydrate and ferrous chloride tetrahydrate are dissolved in deionized water, salmon sperm DNA is added, and ammonia is added under nitrogen protection for reaction. Magnetic separation yields iron oxide particles; iron oxide is dispersed in an ethanol-water mixed solvent, glucose solution and ammonia are added, and after reaction at room temperature, magnetic separation yields the core-shell material; the core-shell material is impregnated in a mixed solution of palladium chloride and cobalt nitrate, ultrasonically adsorbed, and then reduced with tannic acid to obtain the magnetic core-shell bimetallic catalyst.

4. The method for synthesizing DIPPN based on propionitrile according to claim 1, characterized in that, In step S2, the molecular sieve is a 3Å molecular sieve with an adsorption temperature of 20-40℃ and an adsorption pressure of 0.1-0.5MPa; the first-stage condensation temperature is -5-5℃, and the second-stage condensation temperature is -15-10℃.

5. The method for synthesizing DIPPN based on propionitrile according to claim 1, characterized in that, In step S3, the inert atmosphere is nitrogen; the volume ratio of isopropyl bromide to ethyl lactate is 1:2-3; the volume ratio of propionitrile, sodium amino acid and tea saponin is 1:0.2-0.3:0.06-0.1; the volume ratio of premix to reaction system is 2-2.4:1; the reaction temperature is 40-60℃; and the reaction time is 4-6h.

6. The method for synthesizing DIPPN based on propionitrile according to claim 1, characterized in that, In step S4, electrolytic regeneration is performed using an ion-exchange membrane electrolyzer, with the following electrolysis conditions: current density 100-300 A / m³. 2 The voltage is 3-6V and the electrolysis temperature is 30-60℃. The concentration of sodium hydroxide obtained is 20-30wt%. Sodium hydroxide is reacted with liquid ammonia to prepare sodium amino. The obtained bromine gas is condensed and liquefied to obtain liquid bromine. Liquid bromine is reacted with isopropanol at 40-60℃ to synthesize isopropyl bromide.

7. The method for synthesizing DIPPN based on propionitrile according to claim 1, characterized in that, The conditions for vacuum distillation in step S5 are: pressure -0.10 to 0.08 MPa, temperature 40 to 60 °C; the conditions for ultrasonic-assisted cooling crystallization are: mass ratio of n-heptane to residue 3-5:1, ultrasonic power 100-300 W, frequency 20-40 kHz, cooling rate 1-2 °C / min, and cooling to -10 to 0 °C for 2-4 h for crystallization.

8. A DIPPN synthesized using the DIPPN synthesis method based on propionitrile as described in any one of claims 1-7.

9. The DIPPN according to claim 8, characterized in that, The DIPPN has a purity ≥99.6%, an isopropyl monosubstituted product content ≤0.2%, a melting point of 48.5-49.5℃, and a bulk density of 0.48-0.52 g / cm³. 3 .