Continuous flow process for the preparation of triphenyl phosphate based on ionic liquids
By using an ionic liquid medium in a microchannel reactor for continuous flow preparation of triphenyl phosphate, the problems of high environmental pollution and safety risks in traditional methods have been solved, achieving efficient and low-cost production of triphenyl phosphate.
Patent Information
- Application Number
- CN202610939420.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-26
- Publication Date
- 2026-08-25
AI Technical Summary
Existing methods for synthesizing triphenyl phosphate suffer from problems such as inconvenient storage and use of raw materials, serious environmental pollution, high safety risks, high production costs, and unstable product quality.
Triphenyl phosphate was prepared in a continuous flow process using an ionic liquid as the reaction medium in a microchannel reactor. After crude product was generated by esterification, it was filtered, washed with alkali, washed with acid, and dried under reduced pressure to obtain pure product.
It has achieved environmentally friendly and efficient production, shortened reaction time, improved product quality stability and yield, and reduced production costs.
Smart Images
Figure CN122628082A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of microchannel organic synthesis technology, specifically to a continuous flow preparation method of triphenyl phosphate based on ionic liquids. Background Technology
[0002] Triphenyl phosphate (TPP) is a common halogen-free, environmentally friendly flame retardant that imparts excellent wear resistance, weather resistance, radiation resistance, and electrical insulation properties to polymers. Therefore, it is widely used as a flame-retardant plasticizer for polymers such as cellulose resins, vinyl resins, polyvinyl chloride, natural rubber, and synthetic rubber, and is used in the manufacture of cable materials, conveyor belts, and plastic products.
[0003] The reported methods for synthesizing triphenyl phosphate can be mainly classified into phosphorus pentachloride method, phosphorus trichloride method and phosphorus oxychloride method according to the starting materials.
[0004] The phosphorus pentachloride process uses phosphorus pentachloride and phenol as raw materials. First, they react in dichloromethane solvent to produce chlorophosphine compounds. Then, the prepared chlorophosphine reacts with water and alcohols to ultimately produce aryl phosphate esters. This method suffers from several drawbacks: phosphorus pentachloride is inconvenient to store and use, and its violent reaction with water generates large amounts of hydrogen chloride waste gas or waste hydrochloric acid, resulting in significant environmental pollution.
[0005]
[0006] The phosphorus trichloride process is quite complex. First, phosphorus trichloride reacts with phenol to produce triphenyl phosphite, which is then chlorinated to prepare triphenoxyphosphine dichloride. After hydrolysis, the final product, triphenyl phosphate, is obtained. This method uses chlorine gas for chlorination, which is highly irritating and toxic, and corrosive to production equipment, posing a high safety risk.
[0007]
[0008] The phosphorus oxychloride process is mainly divided into two methods: the high-temperature catalytic method and the aqueous phase reaction method. The high-temperature catalytic method involves stirring phenol, phosphorus oxychloride, and a catalyst until homogeneous, followed by a high-temperature (100-120 °C) catalytic reaction. The aqueous phase reaction method involves simultaneously adding a toluene solution of phosphorus oxychloride and an aqueous solution of NaOH to a toluene solution of phenol under vigorous stirring, followed by vacuum distillation to obtain the product. Both methods are simple to synthesize, but phosphorus oxychloride is easily hydrolyzed, affecting the yield, and the reaction is highly exothermic, posing a high safety risk.
[0009]
[0010] In addition, the synthesis process of these triphenyl phosphates is still carried out in a batch reactor, which is prone to problems such as poor material mixing and unstable product quality due to insufficient stirring. At the same time, the traditional batch production cycle is long, consumes a lot of material and human resources, and has a high overall production cost. Summary of the Invention
[0011] To address the aforementioned problems, this invention provides a continuous flow preparation method for triphenyl phosphate based on ionic liquids. This method eliminates the need for organic solvents, allowing the reaction to proceed directly in the ionic liquid. This facilitates the separation of the product from the reaction system, enabling reuse and reducing costs.
[0012] The technical solution of the present invention is a continuous flow preparation method of triphenyl phosphate based on ionic liquid, characterized by comprising the following steps: (1) Dissolve phosphorus oxychloride in an ionic liquid to obtain feed liquid 1, dissolve phenol and acid-binding agent in an ionic liquid to obtain feed liquid 2, pump feed liquid 1 and feed liquid 2 into a microchannel reactor to carry out esterification reaction, and collect the reaction liquid in a storage tank to obtain crude triphenyl phosphate solution. (2) After filtering, alkali washing, acid washing and vacuum drying of the crude solution obtained in step (1), pure triphenyl phosphate is obtained.
[0013] Further, the ionic liquid is any one or more of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium dicyanamide salt, 1-butyl-3-methylimidazolium tetrafluoroborate, N-butylpyridine tetrafluoroborate, methyltributylammonium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide, and N-butyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide.
[0014] Furthermore, the acid-binding agent is one or more of pyridine, triethylamine, N,N-diisopropylethylamine, and 4-dimethylaminopyridine.
[0015] Furthermore, the molar ratio of phosphorus oxychloride to phenol is 1:3.3-4.0; the molar ratio of phosphorus oxychloride to acid-binding agent is 1:3-3.5; and the molar ratio of phosphorus oxychloride to acid-binding agent is 1:3-3.5.
[0016] Furthermore, in step (1), the concentration of phosphorus oxychloride in feed liquid 1 is 0.1-0.6 mol / L; feed liquid 2 and feed liquid 1 are kept at the same volume.
[0017] Furthermore, in step (1), the esterification reaction temperature is 0-25℃, and the residence time of feed liquid 1 and feed liquid 2 in the reactor is 1-6 min.
[0018] Furthermore, the flow rates of feed liquid 1 and feed liquid 2 pumped into the microchannel reactor are each independently 1.0-6.0 mL / min.
[0019] Furthermore, in step (2), the alkaline washing operation uses any one of NaOH, KOH and LiOH aqueous solution, and the acid washing operation uses any one of HCl, H2SO4 and citric acid aqueous solution. Further, the filtrate after acid washing in step (2) is dehydrated by vacuum distillation and dried to constant weight at 90~105℃ to recover the ionic liquid and catalyst.
[0020] Furthermore, the microchannel reactor is a cavity reactor, and the material is any one of PFA, PTFE, ETFE, FEP and 316 L.
[0021] The present invention has the following beneficial effects: The continuous flow preparation method of triphenyl phosphate provided by this invention is carried out directly in an ionic liquid system. Since ionic liquids have almost no vapor pressure, they can be used to replace organic solvents. They are non-volatile and environmentally friendly. Moreover, there is no loss due to volatilization during separation and purification, which reduces reaction costs.
[0022] This invention utilizes an ionic liquid system to incorporate raw materials for microchannel reactions, effectively increasing the reaction rate, shortening the reaction time, and improving reaction safety. This surpasses the traditional batch reactor reaction's 2... The continuous flow preparation of triphenyl phosphate can be completed in minutes, reducing the time from 3 hours. Furthermore, the obtained triphenyl phosphate product has stable quality, with a yield of over 92% based on phosphorus oxychloride and a purity greater than 99% for the refined product. With continuous operation for several hours and a throughput of 35.0 g / h, kilogram-level production can be achieved in minutes through multi-channel parallel scale-up or size-up strategies, demonstrating a very promising industrial prospect. Attached Figure Description
[0023] Figure 1 The process flow diagram of the continuous flow preparation method of triphenyl phosphate based on ionic liquid provided by the present invention is shown.
[0024] In the diagram, the first plunger pump is A; the second plunger pump is B; the microchannel reactor is C; and the storage tank is D. Detailed Implementation
[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, all raw materials and reagents used are commercially available.
[0026] A continuous flow preparation method for triphenyl phosphate based on ionic liquids, the process flow of which is as follows: Figure 1 As shown, the main steps are: (1) Dissolve phosphorus oxychloride in an ionic liquid to obtain feed liquid 1. Dissolve phenol and acid-binding agent in an ionic liquid to obtain feed liquid 2. Pump feed liquid 1 through a first plunger pump A and feed liquid 2 through a second plunger pump B into a microchannel reactor C to carry out esterification reaction. Collect the reaction liquid in a storage tank D to obtain crude triphenyl phosphate solution. The ionic liquid is any one or more of the following: 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium dicyanamide salt, 1-butyl-3-methylimidazolium tetrafluoroborate, N-butylpyridine tetrafluoroborate, methyltributylammonium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide, and N-butyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide. The acid-binding agent is one or more of pyridine, triethylamine, N,N-diisopropylethylamine, and 4-dimethylaminopyridine. The molar ratio of phosphorus oxychloride to phenol is 1:3.3-4.0; the molar ratio of phosphorus oxychloride to the acid-binding agent is 1:3-3.5; and the molar ratio of phosphorus oxychloride to the acid-binding agent is 1:3-3.5. The concentration of phosphorus oxychloride is 0.1-0.6 mol / L; feed solution 2 and feed solution 1 are kept at equal volumes. The esterification reaction temperature is 0-25℃, the residence time of feed solution 1 and feed solution 2 in the reactor is 1-6 min; the flow rates are independently 1.0-6.0 mL / min. The microchannel reactor is a cavity reactor, and the material is any one of PFA, PTFE, ETFE, FEP, and 316 L.
[0027] (2) The crude solution obtained in step (1) was sequentially filtered, alkali-washed, acid-washed, and dried under reduced pressure to obtain pure triphenyl phosphate. The alkali washing operation used any one of NaOH, KOH, and LiOH aqueous solutions, and the acid washing operation used any one of HCl, H2SO4, and citric acid aqueous solutions. The filtrate after acid washing was dehydrated by reduced pressure distillation and dried to constant weight at 90-105℃ to recover the ionic liquid and catalyst.
[0028] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention.
[0029] Example 1 Take 1.53 g of phosphorus oxychloride, add 15 mL of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, stir and mix well to prepare feed solution A. Take 3.76 g of phenol and 3.54 g of triethylamine, add 15 mL of 1-ethyl-3-methylimidazolium bromide salt, stir and mix well to prepare feed solution B of equal volume. Pump feed solutions A and B into a microchannel reactor at a flow rate of 1.0 mL / min using a first plunger pump and a second plunger pump. Esterification reaction occurs at 10 ℃ for 6 min, producing a solid. Filter to obtain the solid product, wash with NaOH aqueous solution to remove excess phenol, wash again with HCl aqueous solution to remove residual acid-binding agent, and dry under reduced pressure to obtain 2.85 g of triphenyl phosphate. g The purity is above 99%, and the yield, calculated as phosphorus oxychloride, is 87%. The filtrate is a two-phase mixture. After separation, the ionic liquid phase is washed with pure water to recover the ionic liquid. The aqueous phase is distilled under reduced pressure to remove water, dried at 100°C to constant weight, and the acid-binding agent is recovered. The ionic liquid can be reused more than 20 times without decreasing the reaction yield or product.
[0030] Example 2 Take 1.53 g of phosphorus oxychloride, add 25 mL of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, stir and mix well to prepare feed solution A. Take 3.76 g of phenol and 4.28 g of 4-dimethylaminopyridine, add 25 mL of 1-ethyl-3-methylimidazolium bromide salt, stir and mix well to prepare feed solution B of equal volume. Pump feed solutions A and B into a microchannel reactor at a flow rate of 1.0 mL / min using a first plunger pump and a second plunger pump. Esterification reaction occurs at 0 ℃ for 6 min, producing a solid. Filter to obtain the solid product, wash with NaOH aqueous solution to remove excess phenol, wash again with HCl aqueous solution to remove residual acid-binding agent, and dry under reduced pressure to obtain 3.03 g of triphenyl phosphate, with a yield of 93% based on phosphorus oxychloride.
[0031] Example 3 1.53 g of phosphorus oxychloride was mixed with 25 mL of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt to prepare feed solution A. 3.76 g of phenol and 2.77 g of pyridine were mixed with 1-ethyl-3-methylimidazolium bromide salt to prepare feed solution B of equal volume. Feed solutions A and B were pumped into a microchannel reactor at a flow rate of 1.0 mL / min using a first and second plunger pump. Esterification occurred at 25 °C for 6 min, producing a solid. The solid product was filtered, washed with NaOH aqueous solution to remove excess phenol, and then washed again with HCl aqueous solution to remove residual acid-binding agent. After vacuum drying, 2.29 g of triphenyl phosphate was obtained, with a yield of 70% based on phosphorus oxychloride.
[0032] Example 4 1.53 g of phosphorus oxychloride was mixed with 25 mL of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt to prepare feed solution A. 3.76 g of phenol and 4.28 g of 4-dimethylaminopyridine were mixed with 1-ethyl-3-methylimidazolium bromide salt to prepare feed solution B of equal volume. Feed solutions A and B were pumped into a microchannel reactor at a flow rate of 2.0 mL / min using a first and second plunger pump. An esterification reaction occurred at 10 °C for 3 min, producing a solid. The solid product was filtered, washed with NaOH aqueous solution to remove excess phenol, and then washed again with HCl aqueous solution to remove residual acid-binding agent. After vacuum drying, 2.98 g of triphenyl phosphate was obtained, with a yield of 91% based on phosphorus oxychloride.
[0033] Example 5 1.53 g of phosphorus oxychloride was taken, and 25 mL of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt was added to it. The mixture was stirred and mixed to prepare feed solution A. 3.76 g of phenol and 4.28 g of 4-dimethylaminopyridine were taken, and 1-ethyl-3-methylimidazolium bromide salt was added to it. The mixture was stirred and mixed to prepare feed solution B of equal volume. Feed solutions A and B were pumped into a microchannel reactor at a flow rate of 3.0 mL / min using a first plunger pump and a second plunger pump. An esterification reaction occurred at 10 °C for 2 min, producing a solid. The solid product was obtained by filtration, washed with NaOH aqueous solution to remove excess phenol, and washed again with HCl aqueous solution to remove residual acid-binding agent. After vacuum drying, 2.84 g of triphenyl phosphate was obtained, with a yield of 87% based on phosphorus oxychloride.
[0034] Example 6 Take 1.53 g of phosphorus oxychloride, add 25 mL of 1-butyl-3-methylimidazolium tetrafluoroborate, stir and mix well to prepare feed solution A. Take 3.76 g of phenol and 4.28 g of 4-dimethylaminopyridine, add 1-butyl-3-methylimidazolium tetrafluoroborate, stir and mix well to prepare feed solution B of equal volume. Pump feed solutions A and B into a microchannel reactor at a flow rate of 6.0 mL / min using a first plunger pump and a second plunger pump. Esterification reaction occurs at 10 °C for 1 min, producing a solid. Filter to obtain the solid product, wash with NaOH aqueous solution to remove excess phenol, wash again with HCl aqueous solution to remove residual acid-binding agent, and dry under reduced pressure to obtain 2.42 g of pure triphenyl phosphate, with a yield of 74% based on phosphorus oxychloride.
[0035] Example 7 Take 1.53 g of phosphorus oxychloride, add 25 mL of 1-butyl-3-methylimidazolium tetrafluoroborate, stir and mix well to prepare feed solution A. Take 3.10 g of phenol and 3.66 g of 4-dimethylaminopyridine, add 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, stir and mix well to prepare feed solution B of equal volume. Pump feed solutions A and B into a microchannel reactor at a flow rate of 2.0 mL / min using a first plunger pump and a second plunger pump. Esterification reaction occurs at 10 °C for 3 min, producing a solid. Filter to obtain the solid product, wash with NaOH aqueous solution to remove excess phenol, wash again with HCl aqueous solution to remove residual acid-binding agent, and dry under reduced pressure to obtain 2.82 g of pure triphenyl phosphate, with a yield of 87% based on phosphorus oxychloride.
[0036] Example 8 Take 1.53 g of phosphorus oxychloride, add 25 mL of 1-butyl-3-methylimidazolium tetrafluoroborate, stir and mix well to prepare feed solution A. Take 3.23 g of phenol and 3.91 g of 4-dimethylaminopyridine, add 1-ethylpyridine hexafluorophosphate, stir and mix well to prepare feed solution B of equal volume. Pump feed solutions A and B into a microchannel reactor at a flow rate of 2.0 mL / min using a first plunger pump and a second plunger pump. Esterification reaction occurs at 10 ℃ for 3 min, producing a solid. Filter to obtain the solid product, wash with NaOH aqueous solution to remove excess phenol, wash again with HCl aqueous solution to remove residual acid-binding agent, and dry under reduced pressure to obtain 2.94 g of pure triphenyl phosphate, with a yield of 90% based on phosphorus oxychloride.
[0037] Example 9 Take 1.53 g of phosphorus oxychloride and add 25 mL of N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide, stir and mix well to prepare feed solution A. Take 3.48 g of phenol and 4.15 g of 4-dimethylaminopyridine and add 1-ethyl-3-methylimidazolium hexafluorophosphate, stir and mix well to prepare feed solution B of equal volume. Pump feed solutions A and B into a microchannel reactor at a flow rate of 2.0 mL / min using a first plunger pump and a second plunger pump. Esterification reaction occurs at 10 °C for 3 min, producing a solid. Filter to obtain the solid product, wash with NaOH aqueous solution to remove excess phenol, wash again with HCl aqueous solution to remove residual acid-binding agent, and dry under reduced pressure to obtain 2.97 g of pure triphenyl phosphate, with a yield of 91% based on phosphorus oxychloride.
[0038] Example 10 Take 1.53 g of phosphorus oxychloride and add 16.6 mL of N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide, stir and mix well to prepare feed solution A. Take 3.48 g of phenol and 4.15 g of 4-dimethylaminopyridine and add 1-ethyl-3-methylimidazolium hexafluorophosphate, stir and mix well to prepare feed solution B of equal volume. Pump feed solutions A and B into a microchannel reactor at a flow rate of 2.0 mL / min using a first plunger pump and a second plunger pump. Esterification reaction occurs at 10 °C for 3 min, producing a solid. Filter to obtain the solid product, wash with NaOH aqueous solution to remove excess phenol, wash again with HCl aqueous solution to remove residual acid-binding agent, and dry under reduced pressure to obtain 3.0 g of pure triphenyl phosphate, with a yield of 92% based on phosphorus oxychloride.
[0039] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other way. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.
Claims
1. A continuous flow preparation method for triphenyl phosphate based on ionic liquids, characterized in that, Includes the following steps: (1) Dissolve phosphorus oxychloride in an ionic liquid to obtain feed liquid 1, dissolve phenol and acid-binding agent in an ionic liquid to obtain feed liquid 2, pump feed liquid 1 and feed liquid 2 into a microchannel reactor to carry out esterification reaction, and collect the reaction liquid in a storage tank to obtain crude triphenyl phosphate solution. (2) After filtering, alkali washing, acid washing and vacuum drying of the crude solution obtained in step (1), pure triphenyl phosphate is obtained.
2. The method according to claim 1, characterized in that: The ionic liquid is any one or more of 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium perchlorate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-ethylpyridine hexafluorophosphate, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium dicyanamide.
3. The method according to claim 1, characterized in that: The acid-binding agent is one or more of pyridine, triethylamine, N,N-diisopropylethylamine and 4-dimethylaminopyridine.
4. The preparation method according to claim 1, characterized in that: The molar ratio of phosphorus oxychloride to phenol is 1:3.3-4.0; the molar ratio of phosphorus oxychloride to acid-binding agent is 1:3-3.5; the molar ratio of phosphorus oxychloride to acid-binding agent is 1:3-3.
5.
5. The preparation method according to claim 1, characterized in that: In step (1), the concentration of phosphorus oxychloride in feed liquid 1 is 0.1-0.6 mol / L; feed liquid 2 and feed liquid 1 are kept at the same volume.
6. The preparation method according to claim 1, characterized in that: In step (1), the esterification reaction temperature is 0-25℃, and the residence time of feed liquid 1 and feed liquid 2 in the reactor is 1-6 min.
7. The preparation method according to claim 1, characterized in that: The flow rates of feed liquid 1 and feed liquid 2 pumped into the microchannel reactor are each 1.0-6.0 mL / min.
8. The preparation method according to claim 1, characterized in that: In step (2), the alkaline washing operation uses any one of NaOH, KOH and LiOH aqueous solution, and the acid washing operation uses any one of HCl, H2SO4 and citric acid aqueous solution.
9. The preparation method according to claim 1, characterized in that: The filtrate after acid washing in step (2) is dehydrated by vacuum distillation and dried to constant weight at 90~105℃ to recover the ionic liquid and catalyst.
10. The preparation method according to any one of claims 1 to 9, characterized in that: The microchannel reactor is a cavity reactor, and the material is any one of PFA, PTFE, ETFE, FEP and 316 L.