A method for preparing chloroalkyl polyphosphates

Abstract

The present application relates to the field of chemical synthesis, and more particularly to a preparation method of chloroalkyl polyphosphate, comprising the following steps: mixing diethylene glycol with gamma-valerolactone, slowly adding phosphorus oxychloride, and reacting at 20-50 DEG C to generate a reaction liquid containing intermediates; adding gamma-valerolactone and IL@MOFs-P catalyst to the reaction liquid, slowly adding propylene oxide, and reacting under a nitrogen atmosphere at 130-150 DEG C to generate a target product mixture; recovering gamma-valerolactone by distillation, centrifuging the catalyst and recycling it, and purifying the crude product to obtain the final product. The present application uses the green solvent gamma-valerolactone and realizes its recycling, the IL@MOFs-P catalyst has high activity and can be recycled, the reaction conditions are precisely controlled to reduce side reactions, the product yield is more than 90%, the purity is more than 98%, and the present application has the advantages of being green, environmentally friendly, economical and efficient.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis, and in particular to a method for preparing chloroalkyl polyphosphates. Background Technology

[0002] Chlorinated alkyl polyphosphates, as an important class of phosphorus-containing flame retardants, are widely used in plastics, rubber, coatings, and other fields due to their excellent flame retardant efficiency, thermal stability, and compatibility with polymer materials. With increasingly stringent environmental protection requirements, the use of traditional halogen-containing flame retardants is gradually being restricted due to the release of toxic gases during combustion, making phosphorus-containing flame retardants a key area of ​​research for alternatives. Among them, chlorinated alkyl polyphosphates enhance their flame retardant effect through the synergistic effect of phosphorus and chlorine in their molecular structure, while also possessing low smoke and low toxicity properties, leading to continued growth in market demand.

[0003] Currently, the preparation of chloroalkyl polyphosphates mostly employs traditional solvent methods, using benzene or halogenated hydrocarbons as the reaction medium. These solvents suffer from high volatility, high toxicity, and significant environmental pollution, and are difficult to recycle, which is inconsistent with the principles of green chemistry.

[0004] During the reaction, the raw material phosphorus oxychloride is prone to violent hydrolysis in water, leading to raw material loss and increased by-products, requiring strict control of the reaction water environment. At the same time, the ring-opening addition reaction of propylene oxide has high requirements for catalyst activity and selectivity. Traditional catalysts have problems such as uneven dispersion of active sites, easy deactivation, and difficulty in recovery, resulting in low product yield and purity. In addition, problems such as reaction temperature fluctuation and insufficient mass transfer efficiency in the existing process can easily trigger side reactions such as cross-linking and chain scission, further reducing product quality. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing chloroalkyl polyphosphates. By employing novel solvents and catalysts, it solves the problems of high solvent pollution, numerous side reactions, low product yield, and low purity in traditional processes. Specifically, this is achieved through the following technical solutions.

[0006] This invention discloses a method for preparing a chloroalkyl polyphosphate, specifically comprising the following steps:

[0007] Step 1: Add the mixture of diethylene glycol and γ-valerol solvent to a glass reactor equipped with a stirrer and a tail gas absorption device, add phosphorus oxychloride for 5-10 minutes, heat to 20-50℃ and react for 2-3 hours, continuously stir during the reaction and absorb and treat the generated hydrogen chloride gas to obtain a reaction solution containing intermediates.

[0008] Step 2: Add γ-valerolactone and IL@MOFs-P catalyst to the reaction solution of Step 1, add propylene oxide, add over 10-12 min, heat the reactor to 130-150℃, continuously purge with nitrogen, stir at 300-400 r / min, and react for 4-6 hours to obtain a mixture containing chlorinated alkyl polyphosphates.

[0009] Step 3: Transfer the mixture obtained in Step 2 to an atmospheric distillation column for distillation and separation. The temperature of the distillation column is 210-215℃ to obtain γ-valerol recovery liquid and a mixture of chloroalkyl polyphosphate containing IL@MOFs-P catalyst.

[0010] Step 4: After purifying the recovered γ-valerol by adsorption with activated carbon for 1-2 hours, it is then transferred to Step 1 and Step 2 for recycling.

[0011] Step 5: Centrifuge the mixture from Step 3 to obtain a solid catalyst and crude chloroalkyl polyphosphate;

[0012] The IL@MOFs-P catalyst was washed with γ-valerol 2-3 times and then purged with nitrogen at 120°C for 2 hours.

[0013] The crude chloroalkyl polyphosphate was washed twice with deionized water to remove the aqueous phase. Anhydrous sodium sulfate solid particles were added, and after standing for 12 hours, the filtrate was filtered and dried under vacuum to obtain the final product.

[0014] Preferably, in step 2, the preparation method of the IL@MOFs-P catalyst includes the following steps:

[0015] S1: Prepare solution A by mixing zirconium nitrate (mass ratio 10-12:235-285) with N,N-dimethylformamide, and prepare solution B by mixing terephthalic acid (mass ratio 4-5:170-210) with N,N-dimethylformamide. Add solution B dropwise to solution A and react at 120°C for 24 hours. After centrifugation and washing, dry under vacuum at 60°C to obtain UiO-66 support.

[0016] S2: N,N-dimethylacetamide, UiO-66 support, 4-bromobenzenesulfonic acid, triphenylphosphine, potassium carbonate, and tetrakis(triphenylphosphine)palladium were uniformly mixed in a mass ratio of 170-205:4-6:3-3.5:3.8-4.2:1-1.2:0.4-0.5 and reacted at 110°C under nitrogen protection for 18 hours. The mixture was then washed and dried to obtain MOFs-P.

[0017] S3: Prepare solution C by mixing MOFs-P and anhydrous dichloromethane in a mass ratio of 3-4:200-240. Prepare solution D by mixing AlCl3 and anhydrous dichloromethane in a mass ratio of 48-52:80-85. Add solution D dropwise to solution C at a mass ratio of 10-15:205-245, and stir for 6 hours. After centrifugation and washing, allow to stand and dry under nitrogen at 100°C for 6 hours to obtain the IL@MOFs-P catalyst.

[0018] Preferably, in step 1, the molar ratio of γ-valerol, phosphorus oxychloride, and diethylene glycol is 10:2:1.

[0019] Preferably, the molar ratio of γ-valerol, propylene oxide and diethylene glycol in step 2 is 6:4:1.

[0020] Preferably, the total mass of the IL@MOFs-P catalyst added in step 2 is 2% to 5% of the sum of the theoretical mass of the intermediate obtained in step 1 and the mass of propylene oxide.

[0021] Preferably, in step 5, the amount of deionized water added each time during washing is 0.5 times the volume of the crude chloroalkyl polyphosphate; and the mass of the anhydrous sodium sulfate solid particles is 10% of the total mass of the chloroalkyl polyphosphate.

[0022] Preferably, in step 5, the vacuum drying conditions are: temperature 40-50℃, vacuum degree -0.1MPa, and drying time 2-4 hours.

[0023] Preferably, in step S2, the washing and drying process is as follows: wash twice each with N,N-dimethylacetamide and deionized water, and then vacuum dry at 80°C for 2 hours.

[0024] Preferably, in step S3, the washing conditions are: washing twice with anhydrous dichloromethane.

[0025] After adopting the above technical solution, the beneficial effects of the present invention are:

[0026] 1. This invention uses γ-valerolactone as a solvent. Its polar aprotic properties can dissolve both polar and nonpolar substances simultaneously. It also has low hygroscopicity, which can effectively avoid the risk of phosphorus oxychloride hydrolysis in water. Its high boiling point and high heat capacity can buffer the exothermic reaction and reduce side reactions caused by local overheating. At the same time, it is easy to efficiently recover the product by distillation after the reaction, and it can be recycled after purification, thereby reducing production costs and environmental pollution.

[0027] 2. This invention uses an IL@MOFs-P catalyst, which provides a high specific surface area through a zirconium-based MOFs porous support, enhancing the adsorption and mass transfer efficiency of reactants; the active sites promote the ring-opening and addition reactions of propylene oxide through the coordination of metal ions and the synergistic effect of sulfonic acid groups, thereby improving catalytic activity and selectivity; the catalyst can be recycled after washing and drying, solving the problems of rapid deactivation and difficulty in recovery of traditional catalysts.

[0028] 3. During the reaction process, the reaction temperature, stirring rate and raw material addition method are precisely controlled. In step 1, the hydrolysis of phosphorus oxychloride is suppressed by low temperature and slow feeding. In step 2, the catalyst is activated by stable high temperature and nitrogen is introduced to isolate oxygen and reduce the occurrence of side reactions. The post-treatment process uses a combination of distillation, centrifugation, water washing and vacuum drying to effectively remove impurities and moisture. The purity of the final product can reach more than 98%, and the yield is significantly improved.

[0029] 4. The entire process achieves the recycling of solvents and catalysts. The solvent is purified by activated carbon adsorption and the catalyst is regenerated by nitrogen purging, which reduces the emission of "three wastes" and conforms to the concept of green chemistry. At the same time, the reaction parameters are optimized to reduce energy consumption and improve production efficiency, which has good prospects for industrial application. Detailed Implementation

[0030] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0031] This invention provides a method for preparing chloroalkyl polyphosphates, which mainly includes the following steps:

[0032] Step 1

[0033] Diethylene glycol was added to γ-valerol solvent and mixed evenly to form a mixture. The mixture was then added to a glass reactor equipped with a stirrer and a tail gas absorption device. Phosphorus oxychloride was slowly added to the reactor, and the temperature was raised to 20–50°C. The reaction was carried out for 2–3 hours with continuous stirring at a rate of 200–300 r / min. The generated hydrogen chloride gas was absorbed and treated by the tail gas absorption device. After the reaction was completed, a reaction solution containing the intermediate was obtained.

[0034] In the above steps, the molar ratio of γ-valerol, phosphorus oxychloride, and diethylene glycol is 10:2:1.

[0035] The addition time for phosphorus oxychloride is 5 to 10 minutes.

[0036] The reaction raw materials for the formation of the intermediate by reacting diethylene glycol and phosphorus oxychloride in the above steps are as follows:

[0037]

[0038] In the above reaction, the hydroxyl oxygen atom in diethylene glycol attacks the chlorine atom attached to the phosphorus atom in phosphorus oxychloride, resulting in nucleophilic substitution. The chlorine atom is replaced by an alkoxy group, and hydrogen chloride is released, generating an intermediate containing phosphorus-oxygen-carbon bonds, thus constructing a preliminary phosphorus-oxygen skeleton.

[0039] In the above reaction process, γ-valerol is used as a solvent because γ-valerol is a polar aprotic solvent with good solubility for both polar and nonpolar substances, and its low hygroscopicity ensures that the reaction is carried out in a low-water environment, avoiding the risk of severe hydrolysis of phosphorus oxychloride in water.

[0040] In addition, the boiling point of γ-valerol is about 207℃, which is significantly different from the boiling points of the reactants phosphorus oxychloride and diethylene glycol, thus facilitating the recovery and utilization of γ-valerol after the reaction. Furthermore, the above reaction process is highly exothermic, and the high heat capacity and high boiling point of γ-valerol can effectively buffer the heat release and avoid side reactions caused by local overheating.

[0041] During the above steps, controlling the temperature between 20 and 50°C and slowly adding phosphorus oxychloride can control the reaction rate and the temperature balance of the system, avoiding excessive local temperature which could lead to phosphorus oxychloride hydrolysis or exacerbate side reactions. In addition, the above temperature range can ensure a faster reaction rate and improve the efficiency of the reaction.

[0042] Step 2

[0043] Add γ-valerol and IL@MOFs-P catalyst to the reaction solution obtained in step 1, and then slowly add propylene oxide over a period of 10 to 12 minutes. After the addition is complete, heat the reactor to 130 to 150°C and continuously introduce nitrogen gas into the reactor. During the reaction, maintain the stirring rate at 300 to 400 r / min and control the reaction time at 4 to 6 hours. After the reaction is completed, a mixture containing the final target product chloroalkyl polyphosphate is obtained.

[0044] The molar ratio of γ-valerol, propylene oxide, and diethylene glycol in step 1 is 6:4:1.

[0045] The total mass of the IL@MOFs-P catalyst added in the above steps is 2% to 5% of the sum of the theoretical mass of the intermediate obtained in step 1 and the mass of propylene oxide.

[0046] During the above reaction process, it is necessary to control the temperature inside the reactor to remain stable, with temperature fluctuations not exceeding 1℃ / min.

[0047] In the above steps, the intermediate obtained in step 1 undergoes a ring-opening addition reaction with propylene oxide under the action of an IL@MOFs-P catalyst. The reaction principle is as follows:

[0048]

[0049] The three-membered ring structure of propylene oxide has high strain. The epoxy bond of propylene oxide is affected by the induction and polarization of the epoxy bond by the phosphorus-containing structure in the intermediate. Under the action of the active site of the catalyst, ring opening occurs. The chlorine atom connected to the phosphorus in the intermediate is replaced by the alkoxy group after the ring opening of propylene oxide, forming the main chain structure of chloroalkyl polyphosphate.

[0050] In the above steps, adding additional γ-valerol can further adjust the polarity of the system, ensuring that the reaction proceeds efficiently and rapidly.

[0051] During the above reaction process, the temperature fluctuation does not exceed 1℃ / min. The ring-opening reaction of propylene oxide is sensitive to temperature. A stable temperature can ensure the selectivity of the reaction and reduce side reactions such as cross-linking and chain scission.

[0052] During the above reaction process, the temperature of the system is controlled at 130-150℃. Within this temperature range, the active sites of the catalyst can be effectively activated, promoting the ring-opening reaction of propylene oxide. Maintaining a stirring rate of 300-400 r / min during the reaction can enhance the three-phase mass transfer of gas, liquid, and solid. Sufficient contact between the liquid reactants and the solid catalyst can promote the increase of the reaction rate. Nitrogen can effectively isolate oxygen, preventing catalyst oxidation and deactivation, and product oxidation and degradation.

[0053] The preparation method of the IL@MOFs-P catalyst in the above steps is as follows:

[0054] S1, Synthetic zirconium-based MOFs support

[0055] Zirconium nitrate was dissolved in N,N-dimethylformamide and stirred until clear to prepare solution A for later use; terephthalic acid was dissolved in N,N-dimethylformamide and stirred until a suspension was formed to prepare solution B for later use.

[0056] Solution B was slowly added dropwise to solution A, stirred for 30 min, transferred to a polytetrafluoroethylene reactor, and reacted at 120 °C for 24 hours. After that, the mixture was naturally cooled to room temperature. The mixture was then centrifuged and washed twice each with N,N-dimethylformamide and methanol. After drying under vacuum at 60 °C for 2 hours, UiO-66 powder was obtained for later use.

[0057] In solution A, the mass ratio of zirconium nitrate to N,N-dimethylformamide is 10–12:235–285; in solution B, the mass ratio of terephthalic acid to N,N-dimethylformamide is 4–5:170–210.

[0058] This step involves reacting zirconium nitrate with terephthalic acid via a solvothermal reaction to form UiO-66 crystal powder with a porous structure. Its high specific surface area and regular channels provide sufficient active sites for subsequent modification, adsorbing and enriching the reactants, thereby promoting the reaction.

[0059] In addition, washing the UiO-66 crystal powder multiple times can effectively remove unreacted raw materials and impurities, and finally vacuum drying at 60°C helps to maintain the crystal structure and prevent the crystal structure from collapsing.

[0060] S2, Grafting Modification

[0061] UiO-66 powder was dispersed in N,N-dimethylacetamide, and 4-bromobenzenesulfonic acid, triphenylphosphine, potassium carbonate, and tetra(triphenylphosphine)palladium were added. The mixture was stirred and reacted at 110°C under a nitrogen atmosphere for 18 hours. The mixture was washed twice each with N,N-dimethylacetamide and deionized water, and dried under vacuum at 80°C for 2 hours to obtain the UiO-66-PPh2-C6H4-SO3H intermediate, denoted as MOFs-P.

[0062] The mass ratio of N,N-dimethylacetamide, UiO-66 powder, 4-bromobenzenesulfonic acid, triphenylphosphine, potassium carbonate, and tetra(triphenylphosphine)palladium used in the above process is 170–205:4–6:3–3.5:3.8–4.2:1–1.2:0.4–0.5.

[0063] This process grafts functional groups such as 4-bromobenzenesulfonic acid onto the surface of UiO-66 crystals via a coupling reaction, introducing sulfonic acid groups (-SO3H) and phosphine ligands (-PPh2) into the surface layer of UiO-66 crystals, thereby endowing the carrier with acidic sites and coordination ability, and significantly enhancing its ion-loading capacity.

[0064] In addition, nitrogen protection is used throughout the above process to prevent the catalyst from oxidizing and losing its activity.

[0065] S3, Load Anchoring

[0066] Disperse MOFs-P in anhydrous dichloromethane and designate it as solution C for later use; disperse AlCl3 in anhydrous dichloromethane and designate it as solution D for later use.

[0067] A small amount of solution D was slowly added dropwise to solution C at -5 to 5°C. After the addition was complete, the temperature was restored to room temperature, and the mixture was stirred for 6 hours. The mixture was then centrifuged and washed twice with anhydrous dichloromethane. Finally, it was transferred to a nitrogen atmosphere at 100°C and allowed to stand and dry for 6 hours to obtain the IL@MOFs-P catalyst.

[0068] In solution C, the mass ratio of MOFs-P to anhydrous dichloromethane is 3–4:200–240; in solution D, the mass ratio of AlCl3 to anhydrous dichloromethane is 48–52:80–85.

[0069] The mass ratio of solution D to solution C is 10–15:205–245.

[0070] During this process, AlCl3 coordinates with the functional groups on the surface of MOFs-P to form an ionic liquid active center, which is then anchored on the MOF support.

[0071] AlCl3 can interact with other components in the system to further regulate the electron cloud density and spatial structure of active sites. After coordinating with functional groups on the surface of MOFs-P, it can enhance the adsorption capacity and activation effect of active sites on reactants, optimize the transition state structure of the reaction, reduce the activation energy of the reaction, thereby improving the activity and selectivity of the catalyst and promoting the formation of chloroalkyl polyphosphates.

[0072] The above reaction process is carried out under low temperature conditions of -5 to 5℃, which can effectively reduce the hydrolysis reaction of AlCl3. In addition, standing in a nitrogen environment can effectively activate the catalytic sites, thereby enabling the porous structure and active center of the catalyst to synergistically improve the reaction selectivity and efficiency.

[0073] In summary, zirconium-based MOFs supports possess a porous structure, which provides a large specific surface area for the reaction. On the one hand, a large number of active sites can be loaded on the surface of the pores of the support, increasing the number of active sites. On the other hand, the porous structure facilitates the diffusion of reactants and products.

[0074] During the reaction, the intermediate and propylene oxide can rapidly diffuse into the pores, fully contact the active sites, and react. The chloroalkyl polyphosphates generated in the reaction can also diffuse out of the pores in a timely manner, avoiding the accumulation of products on the active sites, thereby reducing the inhibitory effect of the products on the reaction and ensuring the efficient catalytic reaction.

[0075] In addition, the metal ions and organic ligands in the IL@MOFs-P catalyst together constitute abundant active sites. Metal ions such as zirconium on the active sites of the catalyst can coordinate with oxygen atoms in propylene oxide molecules, thereby changing the electron cloud distribution of propylene oxide molecules and further increasing the ring strain. Meanwhile, acidic sites such as sulfonic acid groups can provide protons to electrophilically attack the three-membered ring of propylene oxide, promoting ring opening of propylene oxide.

[0076] The active groups in the intermediates also interact with the active sites of the catalyst, enabling the intermediates and propylene oxide to be effectively adsorbed and enriched on the catalyst surface, increasing the probability of collisions between them and thus accelerating the reaction.

[0077] Therefore, the IL@MOFs-P catalyst increases active sites through its porous structure, promotes full contact of reactants, and lowers the activation energy of the reaction by coupling specific metal ions and groups, thereby promoting the ring-opening and addition reactions of propylene oxide and effectively improving the production efficiency of the target product, chloroalkyl polyphosphate.

[0078] Step 3

[0079] The mixture containing the final target product, chloroalkyl polyphosphate, obtained in step 2 was transferred to an atmospheric distillation column. The distillation column temperature was set to 210–215 °C for the distillation separation of γ-valerol. γ-valerol was recovered at the top of the column, and the remaining mixture in the distillation column was the mixture of IL@MOFs-P catalyst and the target product, chloroalkyl polyphosphate.

[0080] In the above steps, the solvent and reaction system are separated by atmospheric distillation at 210–215 °C, taking advantage of the difference in boiling points between γ-valerolactone and the product. This step can efficiently recover the solvent, reduce production costs, and lay the foundation for subsequent product purification.

[0081] Step 4

[0082] The γ-valerol recovered from the top of the column is adsorbed by activated carbon for 1-2 hours to obtain purified γ-valerol, which is then recycled to steps 1 and 2.

[0083] In this step, the γ-valerol recovered by distillation may contain trace impurities. These impurities and pigments can be removed by activated carbon adsorption, thereby improving the purity of the solvent.

[0084] In addition, the refined solvent is recycled for steps 1 and 2, realizing resource recycling, reducing production costs, and reducing the emission of "three wastes", which is more in line with the concept of green chemistry.

[0085] Step 5

[0086] The mixture of the remaining IL@MOFs-P catalyst and the target product chloroalkyl polyphosphate in the distillation column was centrifuged to obtain a solid catalyst and crude chloroalkyl polyphosphate.

[0087] The separated IL@MOFs-P catalyst was washed 2-3 times with γ-valerol and then purged with nitrogen at 120°C for 2 hours.

[0088] The separated crude chloroalkyl polyphosphate was washed twice with deionized water. After washing, the aqueous phase was removed, and anhydrous sodium sulfate solid particles were added to the remaining liquid. After standing for 12 hours, the anhydrous sodium sulfate solid particles were removed by filtration. Then, the remaining chloroalkyl polyphosphate was transferred to an environment of 40-50°C and a vacuum degree of -0.1MPa and dried for 2-4 hours to obtain the final product chloroalkyl polyphosphate.

[0089] Each time, the amount of deionized water added is 0.5 times the volume of the crude chloroalkyl polyphosphate.

[0090] The mass of the added anhydrous sodium sulfate solid particles is 10% of the total mass of chloroalkyl polyphosphate esters.

[0091] In the above process, the solid catalyst and liquid product are physically separated by centrifugation, and soluble impurities and water in the product are removed by washing and drying, finally obtaining the high-purity target product.

[0092] During the catalyst treatment process, washing with γ-valerol 2 to 3 times can remove residual products and impurities on the catalyst surface. Purging with nitrogen at 120°C for 2 hours dries the catalyst and restores the surface active sites, creating conditions for recycling.

[0093] In the purification process of the final product, chloroalkyl polyphosphate, washing twice with deionized water can remove water-soluble impurities in the system. Using 0.5 times the volume of deionized water avoids excessive deionized water from increasing subsequent drying energy consumption. Sufficient anhydrous sodium sulfate desiccant can fully adsorb residual moisture to ensure drying effect. Finally, vacuum drying is carried out at 40-50℃. The vacuum environment can avoid product decomposition and efficiently remove residual moisture, ensuring product purity and stability.

[0094] To facilitate a further understanding of the present invention, several embodiments and comparative examples are given below.

[0095] Example 1

[0096] This embodiment provides a method for preparing chloroalkyl polyphosphate, specifically including the following steps:

[0097] I. Preparation of Catalysts

[0098] S1, Synthetic zirconium-based MOFs support

[0099] Dissolve 20g of zirconium nitrate in 500g of N,N-dimethylformamide and stir until clear to prepare solution A for later use; dissolve 10g of terephthalic acid in 380g of N,N-dimethylformamide and stir until a suspension is formed to prepare solution B for later use.

[0100] Solution B was slowly added dropwise to solution A, stirred for 30 min, transferred to a polytetrafluoroethylene reactor, and reacted at 120 °C for 24 hours. After that, the mixture was naturally cooled to room temperature. The mixture was then centrifuged and washed twice each with N,N-dimethylformamide and methanol. After drying under vacuum at 60 °C for 2 hours, UiO-66 powder was obtained for later use.

[0101] S2, Grafting Modification

[0102] 15g of UiO-66 powder was dispersed in 540g of N,N-dimethylacetamide, and 10g of 4-bromobenzenesulfonic acid, 12g of triphenylphosphine, 3.5g of potassium carbonate, and 1.5g of tetra(triphenylphosphine)palladium were added. The mixture was stirred and reacted at 110℃ under a nitrogen atmosphere for 18 hours. The mixture was washed twice each with N,N-dimethylacetamide and deionized water, and dried under vacuum at 80℃ for 2 hours to obtain the UiO-66-PPh2-C6H4-SO3H intermediate, denoted as MOFs-P.

[0103] S3, Load Anchoring

[0104] Take 20g of MOFs-P and disperse it in 1000g of anhydrous dichloromethane, and designate it as solution C for later use; take 50g of AlCl3 and disperse it in 85g of anhydrous dichloromethane, and designate it as solution D for later use.

[0105] Solution D and solution C were added dropwise to solution C at a mass ratio of 1:14. Solution D was slowly added dropwise to solution C at -5 to 5°C. After the addition was completed, the solution was brought back to room temperature and stirred for 6 hours. The solution was then centrifuged and washed twice with anhydrous dichloromethane. The solution was then transferred to a nitrogen atmosphere at 100°C and allowed to stand and dry for 6 hours to obtain the IL@MOFs-P catalyst.

[0106] II. Preparation of Chlorinated Alkyl Polyphosphates

[0107] Step 1

[0108] 1 mol of diethylene glycol was added to 10 mol of γ-valerol solvent and mixed thoroughly to form a mixture. The mixture was then added to a glass reactor equipped with a stirrer and a tail gas absorption device. 2 mol of phosphorus oxychloride was slowly added to the reactor over a period of 6 minutes. The temperature was raised to 40°C and the reaction was carried out for 2.5 hours. The mixture was stirred continuously at a rate of 250 r / min. The generated hydrogen chloride gas was absorbed and treated by the tail gas absorption device. After the reaction was completed, a reaction solution containing the intermediate was obtained.

[0109] Step 2

[0110] Add 6 mol of γ-valerolactone and 20 g of IL@MOFs-P catalyst to the reaction solution obtained in step 1, and then slowly add 4 mol of propylene oxide over 10 min. After the addition is complete, heat the reactor to 140 °C and continuously introduce nitrogen into the reactor. During the reaction, maintain the stirring rate at 350 r / min and control the reaction time at 5 hours. After the reaction is completed, a mixture containing the final target product chloroalkyl polyphosphate is obtained.

[0111] Step 3

[0112] The mixture containing the final target product, chloroalkyl polyphosphate, obtained in step 2 was transferred to an atmospheric distillation column. The distillation column temperature was set to 212°C to perform distillation separation of γ-valerol. γ-valerol was recovered at the top of the column, and the remaining mixture in the distillation column was the mixture of IL@MOFs-P catalyst and the target product, chloroalkyl polyphosphate.

[0113] Step 4

[0114] The γ-valerol recovered from the top of the column was adsorbed by activated carbon for 2 hours to obtain purified γ-valerol. Steps 1 and 2 were then recycled.

[0115] Step 5

[0116] The mixture of the remaining IL@MOFs-P catalyst and the target product chloroalkyl polyphosphate in the distillation column was centrifuged to obtain a solid catalyst and crude chloroalkyl polyphosphate.

[0117] The separated IL@MOFs-P catalyst was washed three times with γ-valerol and then purged with nitrogen at 120°C for 2 hours.

[0118] The separated crude chloroalkyl polyphosphate was washed twice with deionized water. After washing, the aqueous phase was removed, and 10% of the total mass of the chloroalkyl polyphosphate was added to the remaining liquid as anhydrous sodium sulfate solid particles. After standing for 12 hours, the anhydrous sodium sulfate solid particles were removed by filtration. Then, the remaining chloroalkyl polyphosphate was transferred to an environment of 40°C and a vacuum degree of -0.1 MPa and dried for 3 hours to obtain the final product chloroalkyl polyphosphate.

[0119] Example 2

[0120] This embodiment is based on Example 1, but with adjustments made to step 2 of the preparation of chloroalkyl polyphosphates, reducing the amount of IL@MOFs-P catalyst. Specifically:

[0121] Step 2

[0122] Add 6 mol of γ-valerolactone and 15 g of IL@MOFs-P catalyst to the reaction solution obtained in step 1, and then slowly add 4 mol of propylene oxide over 10 min. After the addition is complete, heat the reactor to 140 °C and continuously introduce nitrogen into the reactor. During the reaction, maintain the stirring rate at 350 r / min and control the reaction time at 5 hours. After the reaction is completed, a mixture containing the final target product chloroalkyl polyphosphate is obtained.

[0123] The remaining steps are exactly the same as in Example 1.

[0124] Example 3

[0125] This embodiment is based on Example 1, but with adjustments made to step S2 of the catalyst preparation process, specifically adjusting the amount of each component added:

[0126] S2, Grafting Modification

[0127] 15g of UiO-66 powder was dispersed in 540g of N,N-dimethylacetamide, and 9g of 4-bromobenzenesulfonic acid, 11.5g of triphenylphosphine, 3g of potassium carbonate, and 1.2g of tetra(triphenylphosphine)palladium were added. The mixture was stirred and reacted at 110℃ under a nitrogen protective atmosphere for 18 hours. The mixture was washed twice each with N,N-dimethylacetamide and deionized water, and dried under vacuum at 80℃ for 2 hours to obtain the UiO-66-PPh2-C6H4-SO3H intermediate, denoted as MOFs-P.

[0128] The remaining steps are exactly the same as in Example 1.

[0129] Comparative Example 1

[0130] This comparative example is based on Example 1, but the S3 step of the catalyst preparation process is adjusted. After centrifugation and washing, the IL@MOFs-P catalyst is directly obtained, specifically as follows:

[0131] S3, Load Anchoring

[0132] Take 20g of MOFs-P and disperse it in 1000g of anhydrous dichloromethane, and designate it as solution C for later use; take 50g of AlCl3 and disperse it in 85g of anhydrous dichloromethane, and designate it as solution D for later use.

[0133] Solution D and solution C were added dropwise to solution C at a mass ratio of 1:14. Solution D was slowly added dropwise to solution C at -5 to 5°C. After the addition was completed, the temperature was restored to room temperature, and the mixture was stirred for 6 hours. The mixture was then centrifuged and washed twice with anhydrous dichloromethane to obtain the IL@MOFs-P catalyst.

[0134] The remaining steps are exactly the same as in Example 1.

[0135] Comparative Example 2

[0136] This comparative example is based on Example 1, but with adjustments made to step 2 of the preparation of chloroalkyl polyphosphates. γ-valerol is no longer added to the reaction solution. Specifically:

[0137] Step 2

[0138] Add 20g of IL@MOFs-P catalyst to the reaction solution obtained in step 1, and then slowly add 4mol of propylene oxide over 10min. After the addition is complete, heat the reactor to 140℃ and continuously introduce nitrogen into the reactor. During the reaction, maintain the stirring rate at 350r / min and control the reaction time at 5 hours. After the reaction is completed, a mixture containing the final target product chloroalkyl polyphosphate is obtained.

[0139] The remaining steps are exactly the same as in Example 1.

[0140] Comparative Example 3

[0141] This comparative example is based on Example 1, but with adjustments made to step 5 of the preparation of chloroalkyl polyphosphate, shortening the vacuum drying process of the final product chloroalkyl polyphosphate. Specifically:

[0142] Step 5

[0143] The mixture of the remaining IL@MOFs-P catalyst and the target product chloroalkyl polyphosphate in the distillation column was centrifuged to obtain a solid catalyst and crude chloroalkyl polyphosphate.

[0144] The separated IL@MOFs-P catalyst was washed three times with γ-valerol and then purged with nitrogen at 120°C for 2 hours.

[0145] The separated crude chloroalkyl polyphosphate was washed twice with deionized water. After washing, the aqueous phase was removed, and 10% of the total mass of the chloroalkyl polyphosphate was added to the remaining liquid as anhydrous sodium sulfate solid particles. After standing for 12 hours, the anhydrous sodium sulfate solid particles were removed by filtration to obtain the final product, chloroalkyl polyphosphate.

[0146] The remaining steps are exactly the same as in Example 1.

[0147] Based on the steps and procedures of the above examples and comparative examples, chloroalkyl polyphosphates were prepared. After preparation, the yield and purity of the chloroalkyl polyphosphates were detected and calculated. The purity and recovery rate of the solvent γ-valerol were detected and calculated. The activity of the recovered catalyst was detected. The data were recorded and statistically analyzed as follows:

[0148]

[0149] Analyzing the above data, we can draw the following conclusions:

[0150] Based on the data comparison of Examples 1 and 3 and Comparative Example 1, the influence of the catalyst can be understood.

[0151] In Example 3, the amount of grafted modified raw materials was reduced by approximately 10% of 4-bromobenzenesulfonic acid and 4.2% of triphenylphosphine. This resulted in insufficient functional group density on the support surface, reduced the number of active sites, and weakened the adsorption and enrichment effect of the reactants, leading to a 2.4% decrease in the final product yield.

[0152] In Comparative Example 1, the high-temperature static drying process under nitrogen was omitted, which resulted in AlCl3 not completely forming stable ionic liquid sites with the sulfonic acid groups of MOFs-P. This reduced the activation ability of propylene oxide during the reaction, leading to a decrease in catalyst activity. Furthermore, the unactivated catalyst surface may have residual solvent molecules that block the pores, further affecting the reaction.

[0153] Based on the comparison of data from Example 1, Example 2, and Comparative Example 2, the influence of process conditions can be observed.

[0154] In Example 2, the amount of catalyst used was changed from 20g to 15g, a reduction of 25%, which led to a 4.2% decrease in the final yield of the product. This indicates that reducing the amount of catalyst used has a certain impact on the final completion rate of the reaction. However, since there is a minimum effective loading of catalyst, the reaction rate increase is limited when the amount is excessive, so the impact on the final yield is limited.

[0155] In Comparative Example 2, the absence of additional γ-valerol lactone resulted in insufficient polarity of the system, leading to a decrease in the mass transfer efficiency between the intermediate and propylene oxide. Simultaneously, the mixing of the gas, liquid, and solid phases was insufficient, increasing side reactions and ultimately reducing the yield of the final product by 8.8%.

[0156] Based on the comparison of data from Example 1 and Comparative Example 3, the impact of post-processing can be observed.

[0157] The vacuum drying step was omitted in Comparative Example 3, which led to a sharp increase in the moisture content of the product and a significant decrease in purity. This shows that vacuum drying is the core of moisture control. Anhydrous sodium sulfate can only adsorb free water, while the vacuum environment can remove bound water and avoid hydrolysis and deterioration of the product.

[0158] The embodiments described above are not exhaustive, nor do they limit the invention to any specific embodiments. Clearly, many modifications and variations can be made based on the above description. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A process for the preparation of chloroalkyl polyphosphates, characterized in that, Comprising the following steps: Step 1: Add a mixture of diethylene glycol and gamma-valerolactone solvent to a glass reaction kettle with stirring and tail gas absorption device, add phosphorus oxychloride, the addition time is 5-10 min, and the temperature is raised to 20-50 DEG C for 2-3 hours, continuously stirring during the reaction, and absorbing and treating the generated hydrogen chloride gas to obtain a reaction liquid containing intermediates; Step 2: Add gamma-valerolactone and IL@MOFs-P catalyst to the reaction liquid of step 1, add propylene oxide, the addition time is 10-12 min, raise the reaction kettle to 130-150 DEG C, continuously pass nitrogen, the stirring rate is 300-400 r / min, and react for 4-6 hours to obtain a mixed liquid containing chloroalkyl polyphosphate; Step 3: Transfer the mixed liquid obtained in step 2 to a normal pressure distillation column for distillation separation, the distillation column temperature is 210-215 DEG C, and gamma-valerolactone recovery liquid and chloroalkyl polyphosphate mixed liquid containing IL@MOFs-P catalyst are obtained; Step 4: After the recovered gamma-valerolactone is refined by activated carbon adsorption for 1-2 h, it is transported to steps 1 and 2 for recycling; Step 5: Centrifugal separation of the mixed liquid in step 3 to obtain solid catalyst and chloroalkyl polyphosphate crude product; After the IL@MOFs-P catalyst is washed with gamma-valerolactone for 2-3 times, it is nitrogen purged at 120 DEG C for 2 hours; After the chloroalkyl polyphosphate crude product is washed with deionized water for 2 times, the water phase is removed, anhydrous sodium sulfate solid particles are added, and after standing for 12 hours, the filtrate is obtained by filtration, and the final product is obtained after vacuum drying, the vacuum drying conditions are: temperature 40-50 DEG C, vacuum degree-0.1 MPa, and drying time 2-4 hours; The preparation method of the IL@MOFs-P catalyst comprises the following steps: S1: Zirconium nitrate with a mass ratio of 10-12:235-285 is mixed with N,N-dimethylformamide to form solution A, terephthalic acid with a mass ratio of 4-5:170-210 is mixed with N,N-dimethylformamide to form solution B, solution B is added dropwise into solution A, and the mixture is reacted at 120 DEG C for 24 hours, centrifuged and washed, and then vacuum dried at 60 DEG C to obtain a UiO-66 carrier; S2: N,N-dimethylacetamide, UiO-66 carrier, 4-bromobenzenesulfonic acid, triphenylphosphine, potassium carbonate, and tetrakis(triphenylphosphine)palladium are uniformly mixed in a mass ratio of 170-205:4-6:3-3.5:3.8-4.2:1-1.2:0.4-0.5, and the mixture is reacted at 110 DEG C under nitrogen protection for 18 hours, and then washed and dried to obtain MOFs-P, and the washing and drying process is as follows: sequentially washing with N,N-dimethylacetamide and deionized water for 2 times respectively, and then vacuum drying at 80 DEG C for 2 hours; S3: MOFs-P and anhydrous dichloromethane were prepared into solution C with a mass ratio of 3-4:200-240, AlCl3 and anhydrous dichloromethane were prepared into solution D with a mass ratio of 48-52:80-85, solution D was added dropwise into solution C at-5-5℃ with a ratio of solution D:solution C=10-15:205-245, and stirred for 6 hours, centrifuged and washed, and then dried at 100℃ in a nitrogen environment for 6 hours to obtain the IL@MOFs-P catalyst.

2. The method according to claim 1, wherein the chloroalkyl polyphosphates are prepared by the following steps: 1) preparing a solution of γ-valerolactone, phosphorus oxychloride and diethylene glycol; 2) adding IL@MOFs-P catalyst to the solution of step 1) and stirring; 3) adding propylene oxide to the solution of step 2) and stirring; 4) adding water to the solution of step 3) and stirring; 5) adding anhydrous sodium sulfate to the solution of step 4) and stirring; and 6) drying the solution of step 5) to obtain the chloroalkyl polyphosphates. In step 1), the molar ratio of γ-valerolactone, phosphorus oxychloride and diethylene glycol is 10:2:

1.

3. The method according to claim 1, wherein the chloroalkyl polyphosphates are prepared by the following steps: 1) preparing a solution of γ-valerolactone, phosphorus oxychloride and diethylene glycol; 2) adding IL@MOFs-P catalyst to the solution of step 1) and stirring; 3) adding propylene oxide to the solution of step 2) and stirring; 4) adding water to the solution of step 3) and stirring; 5) adding anhydrous sodium sulfate to the solution of step 4) and stirring; and 6) drying the solution of step 5) to obtain the chloroalkyl polyphosphates. In step 2), the molar ratio of γ-valerolactone, propylene oxide and diethylene glycol of step 1) is 6:4:

1.

4. The method according to claim 1, wherein the total mass of IL@MOFs-P catalyst added in step 2) is 2-5% of the total mass of the intermediate obtained in step 1) and propylene oxide.

5. The method according to claim 1, wherein in step 5), the deionized water added each time is 0.5 times the volume of the chloroalkyl polyphosphate crude product, and the mass of anhydrous sodium sulfate solid particles is 10% of the total mass of the chloroalkyl polyphosphate.

6. The method according to claim 1, wherein in step S3, the washing conditions are as follows: washing with anhydrous dichloromethane for 2 times. ​ ​ ​

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