Preparation method of diisooctyl phosphite intermediate and application of intermediate in preparation of P507

Abstract

The invention belongs to the technical field of preparation of fine chemicals, and particularly relates to a preparation method of a diisooctyl phosphite intermediate and application of the intermediate in preparation of P507. The preparation method of the diisooctyl phosphate intermediate comprises the following steps: dropwise adding phosphorus trichloride into isooctyl alcohol in an under-liquid dropwise adding manner for reaction, controlling the dropwise adding speed, dropwise adding pressure and reaction temperature to obtain a diisooctyl phosphate mixture, and carrying out a gas phase ammonia neutralization method or a high-vacuum HCl removal method on the diisooctyl phosphate mixture to obtain the diisooctyl phosphate intermediate. And removing impurities, distilling off the chloro-isooctane, collecting to obtain a chloro-isooctane byproduct, and finally obtaining the diisooctyl phosphite. The preparation method of the diisooctyl phosphite intermediate provided by the invention is simple to operate, mild in condition and good in environmental protection property, and the prepared intermediate is high in purity and high in yield; the invention also provides an application of the diisooctyl phosphite intermediate in preparation of P507, and the prepared P507 is high in purity.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of fine chemicals, and in particular relates to a preparation method of a diisooctyl phosphite intermediate and application of the intermediate in the preparation of P507. Background Art

[0002] P507 (2-ethylhexyl phosphate mono-2-ethylhexyl ester), the structural formula is . P507 is an important organic phosphorus extractant, which is widely used in the separation and purification of rare earth metals, rare metals and transition metals. Due to its excellent extraction performance and selectivity, P507 has important industrial application value in hydrometallurgy, nuclear fuel reprocessing and wastewater treatment. In recent years, with the increasing strategic position of rare earth resources, the demand for P507 has continued to grow, and the requirements for its purity and performance have also increased. At present, there are mainly three exploration methods for the synthesis process of P507: one is to use 2-ethylhexyl phosphoryl chloride to react with 2-ethylhexanol to obtain the corresponding phosphonyl chloride, and then hydrolyze to obtain P507; the second is to use 2-ethylhexylphosphonic acid and chloro-2-ethylhexane to react to obtain P507; the third is to use OO-di(2-ethylhexyl)-ethylhexylphosphonate to remove an ester group by hydrolysis to obtain P507. However, the above three methods are prone to generate by-products such as monoesters, diesters, and triesters during the reaction process, which affect the purity and performance of P507. There are also problems with a large number of by-products. In addition, the cost of some raw materials is high and the preparation process is complicated, such as 2-ethylhexyl phosphoryl dichloride and 2-ethylhexylphosphonic acid. There are also problems with harsh reaction conditions and environmental protection. For example, the HCl or alcohol generated by the reaction needs to be neutralized or separated, generating a large amount of wastewater or waste liquid, which increases the environmental protection cost.

[0003] Diisooctyl phosphite (structural formula: ) is a key intermediate in the synthesis of P507 or P204 organophosphorus extractants. Its traditional preparation process has significant technical bottlenecks. The current mainstream process uses phosphorus trichloride and isooctyl alcohol (2-ethylhexanol) to directly react to produce diisooctyl phosphite, but this process has problems such as poor reaction selectivity, many by-products, and low purity of the target product.

[0004] In industrial production, some companies skip the distillation and purification steps to simplify the process and directly enter the subsequent reaction; or use 10% alkaline solution to wash the reaction mixture to remove residual HCl gas and neutralize it to neutral. Although such operations can reduce costs in the short term, they will introduce moisture and cause multiple negative effects: Water and isooctyl alcohol are partially miscible, and the light components evaporated in the synthesis stage of diisooctyl phosphite carry a small amount of water and enter the subsequent esterification reaction system; The intermediate containing water is prone to hydrolysis during distillation and refining, further reducing the purity of the product; Excessive isooctyl alcohol forms a miscible system with water, producing NaCl wastewater with high COD, which increases the difficulty of environmental protection treatment.

[0005] The above problems seriously restrict the large-scale production efficiency and economy of diisooctyl phosphite, and it is urgent to develop new processes to improve reaction selectivity, reduce by-product formation and avoid the introduction of water phase.

[0006] Therefore, diisooctyl phosphite is the first step in the synthesis of P507 organic extractant. The quality of diisooctyl phosphite determines the quality of the subsequent diisooctyl isooctylphosphonate and P507 products. In the synthesis of diisooctyl phosphite, by-products monoester and triester are formed, and diisooctyl phosphite itself is structurally unstable. Under high temperature and acidic and alkaline conditions, it is easy to hydrolyze to form monoester. In the subsequent organic synthesis process, these impurities cannot be separated due to their high boiling points, resulting in high impurity content in P507 products and double peaks in the chromatogram. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a method for preparing a diisooctyl phosphite intermediate. The method has the advantages of simple operation, mild conditions, good environmental protection, and high purity and yield of the prepared intermediate diisooctyl phosphite. The present invention also provides the use of the diisooctyl phosphite intermediate in the preparation of P507, and the prepared P507 has high purity.

[0008] The preparation method of the diisooctyl phosphite intermediate of the present invention comprises the following steps: adding phosphorus trichloride dropwise to isooctyl alcohol ( ), the dropping speed is controlled to be 1.0mL / min~1.5mL / min, the dropping pressure is controlled to be -0.020MPa~-0.030MPa, the reaction temperature is controlled to be 20℃~25℃, the reaction time is 1h~1.5h, and a diisooctyl phosphite mixture is obtained. The diisooctyl phosphite mixture is subjected to gas phase ammonia neutralization method or high vacuum HCl removal method to remove impurities. The acidity is detected to be less than 3.33mgNaOH / g, and chloroisooctane ( ) is distilled out and collected to obtain isooctane chloride as a by-product, and finally diisooctyl phosphite is obtained.

[0009] The specific steps of the gas phase ammonia neutralization method are: introducing a mixed gas of ammonia and nitrogen into the diisooctyl phosphite mixture, stirring, controlling the gas flow rate to 800-1000 mL / min, until the acidity is below 3.33 mg NaOH / g, and then filtering until the filtrate is clear to obtain a deacidified mixed solution. The volume ratio of ammonia to nitrogen is 1:9-2:8.

[0010] The specific steps of the high vacuum HCl removal method are: maintaining the temperature of the diisooctyl phosphite mixture at 55°C to 65°C, using a negative pressure system, at a pressure of -0.090MPa to -0.095MPa, controlling the dropping speed to 3.0mL / min to 4.5mL / min, dripping through a thorn-shaped fractionation column until the acidity is below 3.33mgNaOH / g, and obtaining a deacidified mixed solution.

[0011] The negative pressure system includes a constant pressure funnel, a thorn-shaped fractionation column, a 2XZ-2 rotary vane vacuum pump, a round-bottom flask, a silicone hose, a Y-shaped tube, a rubber stopper, and the like.

[0012] The distillation is carried out at a pressure of -0.095MPa, firstly heating the temperature to 110°C~120°C at a speed of 2.0°C / min~3.0°C / min, until the chloroisooctane is discharged, and then continuing to heat the temperature to 130~150°C for distillation until no chloroisooctane is distilled out.

[0013] During the reaction of the diisooctyl phosphite mixture, the reaction temperature is controlled by an ice-water bath, and during the reaction, the hydrogen chloride gas generated during the reaction is absorbed by a hydrogen chloride absorption device.

[0014] The use of the diisooctyl phosphite intermediate in the preparation of P507 comprises the following steps: (1) Preparation of sodium isooctyl alcohol: heat isooctyl alcohol to 60-70°C, add solid sodium hydroxide and mix, continue heating to 130-150°C, keep warm for 2.5-3.5 hours, remove the heating jacket after the insulation is completed, cool the mixed liquid to the alkali agglomerates, heat and dissolve the solid alkali and transfer it out; transfer the liquid phase to a four-necked flask, turn on the heating jacket, and heat to 130-150°C at a rate of 2.0°C / min-3.0°C / min, paying attention to the liquid and gas phase temperatures. After the distillation is completed, the isooctyl alcohol content is 20%-25%; (2) Condensation of diisooctyl isooctylphosphonate: The prepared diisooctyl phosphite intermediate is mixed with the sodium isooctyl alcohol mixed solution prepared in step (1), and the mixture is heated to 140°C-150°C for reaction until no isooctyl alcohol is distilled out. Then, isooctane chloride collected in the preparation of diisooctyl phosphite intermediate is added, and the mixture is reacted at 180-190°C for 3-4h. The mixture is first cooled to 80-90°C and then heated for distillation until no gas phase is produced. The mixture is cooled to room temperature, water is added to dissolve the mixture, and the mixture is allowed to stand for phase separation. The obtained organic phase is purified at 230-240°C to obtain diisooctyl isooctylphosphonate. (3) Preparation of P507 sodium salt: Mix the prepared diisooctyl isooctylphosphonate with sodium hydroxide solution, heat to 120-130°C and stir, distill at atmospheric pressure for 1.5-2.5 hours, add water and stir at 500-1000 r / min until all dissolved, stop stirring, let stand and drain, and obtain P507 sodium salt; (4) Preparation of P507: Hydrochloric acid is added to the prepared sodium salt of P507 to acidify it so that the pH of the oil phase is 0.8-1.2, and then the water is drained and water is added to the oil phase to wash it until the pH of the oil phase is 4-5. The obtained oil phase is post-treated to obtain P507.

[0015] The mass concentration of the sodium hydroxide solution in step (3) is 46% to 48%; the mass concentration of the hydrochloric acid in step (4) is 34% to 36%.

[0016] The post-treatment step of step (4) is as follows: distilling the obtained oil phase at -0.090MPa~-0.095MPa and a gas phase temperature of 85°C~90°C until no gas phase is generated, and continuing to heat to 160~180°C and distill at a vacuum degree of -0.1MPa until the distillation vapor temperature begins to decrease, and then ending the distillation and dropping to room temperature.

[0017] Specifically, the preparation of P507 comprises the following steps: (1) Phosphorus trichloride is added dropwise to isooctyl alcohol by submerged addition for reaction, the dropping speed is controlled to be 1.0 mL / min to 1.5 mL / min, the dropping pressure is controlled to be -0.020 MPa to -0.030 MPa, the reaction temperature is controlled to be 20°C to 25°C, and the reaction time is 1 h to 1.5 h to obtain a diisooctyl phosphite mixture, the diisooctyl phosphite mixture is subjected to a gas phase ammonia neutralization method or a high vacuum HCl removal method to remove impurities, and the acidity thereof is detected to be less than 3.33 mgNaOH / g, and chloroisooctane is continuously distilled out and collected to obtain chloroisooctane by-product, and finally diisooctyl phosphite is obtained.

[0018] (2) Preparation of sodium isooctyl alcohol: heat isooctyl alcohol to 60-70°C, add solid sodium hydroxide and mix, continue heating to 130-150°C, keep warm for 2.5-3.5 hours, remove the heating jacket after the insulation is completed, cool the mixed liquid to the alkali agglomerates, heat and dissolve the solid alkali and transfer it out; transfer the liquid phase to a four-necked flask, turn on the heating jacket, and heat to 130-150°C at a rate of 2.0°C / min-3.0°C / min, paying attention to the liquid and gas phase temperatures. After the distillation is completed, the isooctyl alcohol content is 20%-25%; (3) Condensation of diisooctyl isooctylphosphonate: The prepared diisooctyl phosphite intermediate is mixed with the sodium isooctyl alcohol mixed solution prepared in step (1), and the mixture is heated to 140°C-150°C for reaction until no isooctyl alcohol is evaporated, and then the isooctane chloride collected in the preparation of the diisooctyl phosphite intermediate is added, and the mixture is reacted at 180-190°C for 3-4h, and the mixture is cooled to 80-90°C for distillation until no gas phase is produced, and the mixture is cooled to room temperature, and water is added to dissolve the mixture, and the mixture is allowed to stand for phase separation. The obtained organic phase is purified at 230-240°C to obtain diisooctyl isooctylphosphonate; (4) Preparation of P507 sodium salt: Mix the prepared diisooctyl isooctylphosphonate with sodium hydroxide solution, heat to 120-130°C and stir, distill at atmospheric pressure for 1.5-2.5 hours, add water and stir at 500-1000 r / min until all dissolved, stop stirring, let stand and drain, and obtain P507 sodium salt; (5) Add hydrochloric acid to the prepared sodium salt of P507 to acidify it so that the pH of the oil phase is 0.8-1.2, then drain the water, add water to the oil phase to wash it until the pH of the oil phase is 4-5, and post-treat the obtained oil phase to obtain P507.

[0019] In the process of preparing diisooctyl phosphite, the present invention adopts submerged dropping, PCl3 is extended to below the isooctyl alcohol liquid surface through a constant pressure funnel dropping conduit, the dropping speed is controlled, a slight negative pressure is maintained during the dropping process, and the negative pressure is increased after the dropping is completed to evaporate most of the HCl gas. The submerged dropping ensures the effective utilization of PCl3, prevents the PCl3 from being sucked away by the negative pressure after being dropped to the liquid surface due to the violent heat release of the reaction between the two, and the submerged dropping ensures the reaction contact area, so that the PCl3 is more effectively utilized.

[0020] The synthesis reaction formula of diisooctyl phosphite of the present invention is: .

[0021] The synthetic reaction formula of diisooctyl isooctylphosphonate is: , .

[0022] The synthetic reaction formula of P507 is: , .

[0023] In the process of preparing diisooctyl phosphite, the present invention adopts a gas phase ammonia neutralization method and a high vacuum HCl removal method. The gas phase ammonia neutralization method is to introduce a mixed gas of ammonia and nitrogen into a mixture of diisooctyl phosphite and chloroisooctane to neutralize the HCl gas therein to form NH4Cl, and the NH4Cl solid is removed by filtering in the later stage. In the high vacuum HCl removal method, under a negative pressure condition of -0.095MPa, the temperature of the mixture is first heated to 60°C, and transferred to a negative pressure system (the system consists of a 1000mL constant pressure funnel, a 1.2m thorn-shaped fractionation column, a 1000mL round-bottom flask, a 2XZ-2 rotary vane vacuum pump, a silicone hose, etc.), and the constant pressure funnel controls the dripping speed to 3.0mL / min~4.5mL / min, drips into the round-bottom flask through the thorn-shaped fractionation column, and the thorn-shaped fractionation column increases the surface area of ​​the material so that the HCl gas therein is easier to separate, and the thorn-shaped fractionation column is kept at 60°C, without by-products and wastewater generation.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation of diisooctyl phosphite of the present invention adopts a gas phase ammonia neutralization method and a high vacuum HCl removal method. No new impurities are formed during the organic synthesis reaction. The yield of the obtained diisooctyl phosphite is equivalent to that of the traditional alkali neutralization method, but its content is higher than that of the diisooctyl phosphite obtained by the alkali neutralization method, and the content is as high as 96%.

[0025] (2) The preparation of diisooctyl phosphite of the present invention adopts the gas phase ammonia neutralization method and the high vacuum HCl removal method, which can greatly reduce the amount of wastewater and reduce the cost of wastewater treatment. However, the large amount of high-salt, high-COD and high-phosphorus wastewater produced has extremely high treatment costs and can only be treated by evaporation and concentration. The cost of treating each ton of wastewater is about 200 yuan. Although the energy consumption of the gas phase ammonia neutralization method of the present invention increases, the cost of each ton of P507 product finally produced by using it can still be reduced by 900 to 950 yuan. Although the high vacuum HCl removal method increases some power consumption, the cost of each ton of P507 product finally produced by using it can still be reduced by about 1,200 yuan. Therefore, compared with the alkali neutralization method used in the traditional deacidification step, the cost of the present invention is low.

[0026] (3) The P507 product prepared by the present invention has a high content and a high yield, which reduces the cost of the entire process production, reduces the treatment of wastewater and waste gas, and reduces the cost of environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the NMR P spectrum of the diisooctyl phosphite intermediate prepared in Example 1.

[0028] Figure 2 This is the NMR P spectrum of the standard sample of diisooctyl phosphite.

[0029] Figure 3 This is the H NMR spectrum of the diisooctyl phosphite intermediate prepared in Example 1.

[0030] Figure 4 This is an internal standard curve diagram of the diisooctyl phosphite intermediate prepared in Example 1 during gas phase detection.

[0031] Figure 5 This is the NMR P spectrum of the diisooctyl phosphite intermediate prepared in Example 3.

[0032] Figure 6 This is the NMR P spectrum of the diisooctyl phosphite intermediate prepared in Comparative Example 1. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with specific embodiments.

[0034] The raw materials and auxiliary agents used in the following examples and comparative examples are all commercially available products. The reaction of the present invention is an organic synthesis reaction. The raw materials used in each step of the reaction can theoretically be reacted according to the molar ratio of the reaction formula, or some excess reactants are used for complete reaction. Therefore, the reaction molar ratio of each step of the present invention is not specifically limited.

[0035] The negative pressure system in the high vacuum HCl removal method described in the following embodiments is composed of a 1000mL constant pressure funnel, a 120cm thorn-shaped fractionation column, a 1000mL three-necked flask, a Y-tube, a silicone hose, and a water circulation vacuum pump. The entire system is closed to form a vacuum state, which is controlled by the following steps: the 1000mL constant pressure funnel is filled with clean water, and the clean water flow rate is controlled by the cock valve of the constant pressure funnel to drip slowly. The water droplets pass through the thorn-shaped fractionation column from top to bottom, and the HCl gas passes through the thorn-shaped fractionation column from bottom to top. The water absorbs HCl, and the absorption liquid is collected in a flask connected to the bottom of the thorn-shaped fractionation column. The circulating water in the circulating vacuum pump further absorbs a very small amount of HCl that is not absorbed in the thorn-shaped fractionation column.

[0036] The traditional detection of the content of diisooctyl phosphite adopts the acid-base titration method. However, when diisooctyl phosphite contains monoester and triester, because its molecule contains -OH, all of them are defaulted to diisooctyl phosphite for content calculation during titration, resulting in inaccurate results. The present invention uses nuclear magnetic resonance and gas chromatography as detection equipment to reduce the error caused by the inaccuracy of the detection method. Through the analysis of the obtained diisooctyl phosphite by nuclear magnetic resonance (P spectrum, H spectrum) and GC, it can be seen that during the alkali neutralization treatment process, due to the hydrolysis of diisooctyl phosphite under acidic and alkaline conditions, the diisooctyl phosphite contains impurity monoester, accounting for 2%-4% of the total content. At the same time, due to the high boiling point of the monoester, it is always retained in the organic phase, which ultimately leads to the reduction of the quality of the P507 product and affects its extraction and separation ability.

[0037] The standard sample of diisooctyl phosphite used in the following examples and comparative examples is a commercially available standard sample, and its content is 96% as determined by P spectrum. The yields mentioned are all obtained by calculating the actual yield / theoretical yield × 100%.

[0038] Example 1 The preparation method of the diisooctyl phosphite intermediate comprises the following steps: (1) Accurately weigh 1.0 mol PCl3 and place it in a 250 mL constant pressure funnel. Measure 3.1 mol isooctyl alcohol and place it in a 1000 mL four-hole flask. Add phosphorus trichloride to the isooctyl alcohol by submerged addition for reaction. The temperature of the liquid in the flask is maintained at 20 °C by controlling the drop rate to 1.0 mL / min and adding an ice-water bath. At the same time, turn on the water circulation vacuum pump to control the pressure at -0.020 MPa during the drop addition. During the vacuuming process, slowly add water to the constant pressure funnel on the HCl absorption device. The absorption liquid is collected in the bottom flask and the acidity is tested. The pressure remains unchanged and the temperature is maintained at 20 °C for 1.5 h to ensure that the materials are fully reacted. Some HCl is still dissolved in the obtained diisooctyl phosphite mixture.

[0039] (2) Deacidification of diisooctyl phosphite mixture by gas phase ammonia neutralization method: In a four-hole flask, a mixture of ammonia and nitrogen in a volume ratio of 1:9 is passed through a pressure regulator to control the gas flow rate to 1000 mL / min. In order to allow ammonia to fully react with HCl, it is introduced into the bottom of the four-hole flask through a porous catheter. Under stirring, the pH of the oil phase is detected with a 5.0-9.0 pH test paper. Based on the color of the test paper, it is preliminarily judged to be above 7, and the ventilation is stopped. Then, a positive pressure filter device (the filter medium is 108C type dense filter cloth) is used to filter out solid NH4Cl. If the solution is not clear, the filtering operation is repeated until the acidity is below 3.33 mgNaOH / g to obtain a deacidified diisooctyl phosphite mixture.

[0040] (3) Distilling the deacidified diisooctyl phosphite mixed solution: the mixed solution was placed in a distillation flask, and the temperature was first slowly raised to 120°C at a rate of 2.0°C / min under -0.095 MPa. After the chloroisooctane was discharged, the temperature was further raised to 150°C for distillation, and the chloroisooctane was collected (the content of chloroisooctane was 88.4%, the content of isooctyl alcohol was 11.6%, and the yield of chloroisooctane was calculated to be 95.7%). After separating the two, diisooctyl phosphite was collected. The content of diisooctyl phosphite was 97.2% as determined by gas chromatography, and the yield was calculated to be 96.1%.

[0041] a. Perform NMR P spectrum detection on the diisooctyl phosphite prepared above. Its NMR P spectrum is as follows: Figure 1 As shown, the NMR P spectrum of the standard sample of diisooctyl phosphite used is as shown in Figure 2 The NMR data comparison data are shown in Table 1.

[0042] Table 1 Comparison of NMR P spectrum data

[0043] It can be seen from Table 1 above that the diisooctyl phosphite obtained by the gas phase ammonia neutralization method for deacidification in the present invention contains a small amount of monoester, no other impurities, and has high purity compared with the standard sample of diisooctyl phosphite.

[0044] b. The prepared diisooctyl phosphite is subjected to nuclear magnetic resonance (NMR) H spectrum detection, and its NMR H spectrum is as follows: Figure 3 As shown, the data of the nuclear magnetic resonance H spectrum of the standard sample of diisooctyl phosphite used, the theoretical prediction data and the actual detection data of the example samples are shown in Table 2.

[0045] Table 2 Data results of H NMR spectrum

[0046] From the comparison of Table 2 above, it can be seen that the peak area integral ratios of the H spectrum of the diisooctyl phosphite prepared in this embodiment are between the theoretical prediction and the standard sample, and there is no large deviation. Therefore, the diisooctyl phosphite of the present invention does not have other impurities during the synthesis process, and no other groups are introduced on P.

[0047] c. The diisooctyl phosphite prepared above was subjected to gas chromatography detection. The internal standard curve of the gas chromatography used was as follows: Figure 4 As shown, the internal standard curve is y=3.0868x+0.051, R 2 =0.9693, wherein the gas phase detection data and the gas chromatography data of the standard sample of diisooctyl phosphite are shown in Table 3.

[0048] Table 3 Gas chromatography data

[0049] The product quality of diisooctyl phosphite obtained from the sample of Example 1 in Table 3 is higher than that of the standard sample of diisooctyl phosphite because the mass percentage of the standard sample of diisooctyl phosphite is 96.0%; in addition, when constructing the working curve, the fitting degree is slightly poor, so the percentage of the experimental sample exceeds 100, but it does not affect the judgment of the quality of the ester. Combined with the data analysis of the nuclear magnetic resonance P spectrum and the H spectrum, it can be seen that the diisooctyl phosphite obtained under the conditions of Example 1 is superior to the standard sample in purity and percentage.

[0050] Example 2 The preparation method of the diisooctyl phosphite intermediate comprises the following steps: (1) Accurately weigh 1.0 mol PCl3 and place it in a 250 mL constant pressure funnel. Measure 3.1 mol isooctyl alcohol and place it in a 1000 mL four-hole flask. Add phosphorus trichloride to the isooctyl alcohol by submerged addition for reaction. The temperature of the liquid in the flask is maintained at 25 °C by controlling the drop rate to 1.5 mL / min and adding an ice-water bath. At the same time, turn on the water circulation vacuum pump to control the pressure at -0.030 MPa during the drop addition. During the vacuuming process, slowly add water to the constant pressure funnel on the HCl absorption device. The absorption liquid is collected in the bottom flask and the acidity is tested. The pressure remains unchanged and the temperature is maintained at 25 °C for 1 h to ensure that the materials are fully reacted. Some HCl is still dissolved in the obtained diisooctyl phosphite mixture.

[0051] (2) Deacidification of diisooctyl phosphite mixture by gas phase ammonia neutralization method: In a four-hole flask, a mixture of ammonia and nitrogen in a volume ratio of 2:8 is passed through a pressure regulator to control the gas flow rate to 800 mL / min. In order to allow ammonia to fully react with HCl, it is introduced into the bottom of the four-hole flask through a porous catheter. Under stirring, the pH of the oil phase is detected with a 5.0-9.0 pH test paper. Based on the color of the test paper, it is preliminarily judged to be above 7, and the ventilation is stopped. Then, a positive pressure filter device (the filter medium is 108C type dense filter cloth) is used to filter out solid NH4Cl. If the solution is not clear, the filtration operation is repeated until the acidity is below 3.33 mgNaOH / g to obtain a deacidified diisooctyl phosphite mixture.

[0052] (3) Distilling the deacidified diisooctyl phosphite mixed solution: the mixed solution was placed in a distillation flask, and the temperature was first slowly raised to 110°C at a rate of 3.0°C / min under -0.095 MPa. After the chloroisooctane was discharged, the temperature was further raised to 130°C for distillation, and the chloroisooctane was collected (the content of chloroisooctane was 87.4%, the content of isooctyl alcohol was 12.6%, and the calculated yield of chloroisooctane was 94.5%). After separating the two, diisooctyl phosphite was collected. The content of diisooctyl phosphite was 96.8% by gas chromatography, and the calculated yield was 95.1%.

[0053] Example 3 The preparation method of the diisooctyl phosphite intermediate comprises the following steps: (1) Accurately weigh 1.0 mol PCl3 and place it in a 250 mL constant pressure funnel. Measure 3.1 mol isooctyl alcohol and place it in a 1000 mL four-hole flask. Add phosphorus trichloride to the isooctyl alcohol by submerged addition for reaction. The temperature of the liquid in the flask is maintained at 20 °C by controlling the drop rate to 1.0 mL / min and adding an ice-water bath. At the same time, turn on the water circulation vacuum pump to control the pressure at -0.020 MPa during the drop addition. During the vacuuming process, slowly add water to the constant pressure funnel on the HCl absorption device. The absorption liquid is collected in the bottom flask and the acidity is tested. The pressure remains unchanged and the temperature is maintained at 20 °C for 1.5 h to ensure that the materials are fully reacted. Some HCl is still dissolved in the obtained diisooctyl phosphite mixture.

[0054] (2) The diisooctyl phosphite mixture was subjected to a high vacuum dehydrogenation method: the diisooctyl phosphite mixture was heated to 65°C and transferred to a negative pressure system. Under a pressure of -0.090 MPa, the dropping rate was controlled by a constant pressure funnel to be 3.5 mL / min, and the mixture was dripped through a barbed distillation column, which was kept at 65°C until the acidity was below 3.33 mg NaOH / g, thereby obtaining a deacidified diisooctyl phosphite mixture.

[0055] (3) Distilling the deacidified diisooctyl phosphite mixed solution: the mixed solution was placed in a distillation flask, and the temperature was first slowly raised to 120°C at a rate of 3.0°C / min under -0.095 MPa. After the chloroisooctane was discharged, the temperature was further raised to 130°C for distillation, and the chloroisooctane was collected (the content of chloroisooctane was 89.3%, the content of isooctyl alcohol was 10.7%, and the calculated yield of chloroisooctane was 96.8%). After separating the two, diisooctyl phosphite was collected. The content of diisooctyl phosphite was 97.3% as determined by gas chromatography, and the calculated yield was 96.9%.

[0056] The prepared diisooctyl phosphite was subjected to nuclear magnetic resonance (NMR) P spectrum detection, and its NMR P spectrum is as follows: Figure 5 Its NMR data are shown in Table 4.

[0057] Table 4 NMR P spectrum data table

[0058] According to the data in Table 4 above, compared with the standard sample data in Table 1, the nuclear magnetic resonance P spectrum of the diisooctyl phosphite sample prepared in this embodiment has an additional signal peak in the peak range of 10.96-9.41, with a percentage content of 1%. Compared with the nuclear magnetic resonance P spectrum of the standard sample, there is no unknown impurity in the peak range of 8.43-6.92. Therefore, the content and purity of the diisooctyl phosphite sample prepared in this embodiment are equivalent to those of the standard sample.

[0059] Example 4 The preparation method of the diisooctyl phosphite intermediate comprises the following steps: (1) Accurately weigh 1.0 mol PCl3 and place it in a 250 mL constant pressure funnel, weigh 3.1 mol isooctyl alcohol and place it in a 1000 mL four-hole flask, and add phosphorus trichloride to the isooctyl alcohol by submerged addition for reaction. The temperature of the liquid in the flask is maintained at 25°C by controlling the drop rate to 1.5 mL / min and adding an ice-water bath. At the same time, turn on the water circulation vacuum pump to control the pressure at -0.030 MPa during the drop addition process. During the vacuuming process, water is slowly added to the constant pressure funnel on the HCl absorption device. The absorption liquid is collected in the bottom flask and the acidity is tested. The pressure remains unchanged and the constant temperature is maintained at 25°C for 1 hour to ensure that the materials are fully reacted. Some HCl is still dissolved in the obtained diisooctyl phosphite mixture. (2) The diisooctyl phosphite mixture was subjected to a high vacuum dehydrogenation method: the diisooctyl phosphite mixture was heated to 55°C and transferred to a negative pressure system. Under a pressure of -0.095 MPa, the dropping rate was controlled by a constant pressure funnel to be 4.5 mL / min, and the mixture was dripped through a barbed distillation column, which was kept at 55°C until the acidity was below 3.33 mg NaOH / g, thereby obtaining a deacidified diisooctyl phosphite mixture.

[0060] (3) Distilling the deacidified diisooctyl phosphite mixed solution: the mixed solution was placed in a distillation flask, and the temperature was first slowly raised to 120°C at a rate of 2.0°C / min under -0.095 MPa. After the chloroisooctane was discharged, the temperature was further raised to 150°C for distillation, and the chloroisooctane was collected (the chloroisooctane content was 88.5%, the isooctyl alcohol content was 11.5%, and the chloroisooctane yield was calculated to be 95.8%). After the two were separated, diisooctyl phosphite was collected, and its content was 97.5% as determined by gas chromatography, and its yield was calculated to be 96.3%.

[0061] Example 5 The preparation of P507 using the diisooctyl phosphite intermediate prepared in Example 1 comprises the following steps: (1) Preparation of sodium isooctyl alcohol: 586 g (4.5 mol) of isooctyl alcohol was accurately weighed and placed in a 1000 mL flask. The heating jacket was turned on and the liquid phase was heated to 60°C. 64.5 g (1.61 mol) of solid NaOH was weighed and added to the flask at once. The liquid phase was heated to 140°C at a rate of 2.0°C / min for distillation and kept warm for 3 h. During the experiment, the state changes of the solid NaOH and the time point when the solid disappeared were recorded. After the insulation was completed, the heating jacket was removed and the mixed liquid was cooled to a base agglomerate. The solid base was heated and dissolved and then transferred out to test the alkalinity. The liquid phase was transferred to a four-necked flask, the heating jacket was turned on, and the temperature was slowly raised. The final heating temperature was controlled at 140°C. After the distillation was completed, the water content of isooctyl alcohol was tested. After gas chromatography, the residual amount of base in the octanol was 0.25 mg NaOH / g and the content of sodium isooctyl alcohol was 22%.

[0062] (2) Condensation of diisooctyl isooctylphosphonate: Accurately weigh 1 mol of diisooctyl phosphite intermediate prepared in Example 1 (actual effective amount 306.4 g), weigh 1.03 mol of sodium isooctyl alcohol (actual effective amount 156.56 g) prepared in step (1), add them all at once into a 2000 mL four-hole flask, turn on the electric heating jacket, and simultaneously turn on the vacuum pump, raise the temperature to 150° C., distill for 2 h, evaporate isooctyl alcohol, distill until no isooctyl alcohol is produced, remove the distillation apparatus, weigh 2.2 mol of chloroisooctane collected in Example 1 and add it to the flask, add a reflux apparatus to the flask, raise the temperature to 170° C., and start temperature control (pay attention to bumping), and keep the temperature at 190° C. for 3 h. After the insulation is completed, cool the temperature to 80° C. for distillation, replace the reflux apparatus with a distillation apparatus, and evaporate chloroisooctane; After the obtained material is cooled, 200 mL of pure water is added to dissolve the NaCl in the material, and the material is transferred to a 1000 mL conical funnel and allowed to stand for phase separation. After the water phase is discharged, the oil phase is transferred to a 1000 mL four-hole flask to distill out water and the front fraction first, and the collection flask is switched to carry out fine distillation of diisooctyl isooctylphosphonate at a temperature of 240 ° C. Distill until no material is discharged to obtain diisooctyl isooctylphosphonate, and its content is detected to be 95.2%.

[0063] (3) Preparation of P507 sodium salt: Add 1.6 mol of 48% sodium hydroxide solution and 1.0 mol of diisooctyl isooctylphosphonate into a 1000 mL four-hole flask, stir, and heat the contents. Open the distillation condenser, slowly increase the temperature, and evaporate isooctyl alcohol under normal pressure. After 2.5 hours, the liquid temperature rises to 120°C, then open the vacuum system, evaporate 50% of the isooctyl alcohol, and use the remaining isooctyl alcohol as a solvent to prevent the contents in the flask from becoming too viscous. At this time, stirring should be stopped in time.

[0064] After the isooctyl alcohol is evaporated, stop heating, turn off the vacuum, add 200 mL of water to the flask to dissolve, make sure to stir at 1000 r / min until all dissolved, start stirring, and after all the solid phase in the flask is dissolved, stop stirring, transfer to a 1000 mL conical flask, let it stand and then discharge the water phase to obtain P507 sodium salt.

[0065] (4) P507 sodium salt was transferred into a four-necked flask, and 1.0 mol hydrochloric acid (mass concentration 36%) was added to acidify until the pH of the oil phase was 1.2, and then the acid water was discharged. Water was then added to stir and wash, so that the final pH of the P507 oil phase was 4. Finally, after washing, P507 was transferred into a four-necked flask, stirred and heated, and the condenser was turned on. Water and isooctyl alcohol were evaporated at 90°C (gas phase temperature) under a vacuum condition of -0.09 MPa. When the liquid temperature reached 145°C, the water ring vacuum pump was switched to a rotary vane vacuum pump. When the liquid temperature reached 180°C and the vacuum was -0.1 MPa, the fraction decreased significantly, and the air temperature began to drop. The isooctyl alcohol distillation process was completed, and the heating was stopped, the condenser and vacuum pump were stopped to obtain P507. The content of P507 was 97.4% detected by the acid-base titration method in the industry, and the yield was calculated to be 86.7%.

[0066] Example 6 The preparation of P507 using the diisooctyl phosphite intermediate prepared in Example 3 comprises the following steps: (1) Preparation of sodium isooctyl alcohol: 586 g (4.5 mol) of isooctyl alcohol was accurately weighed and placed in a 1000 mL flask. The heating jacket was turned on and the liquid phase was heated to 70°C. 64.5 g (1.61 mol) of solid NaOH was weighed and added to the flask at once. The liquid phase was heated to 150°C at a rate of 3.0°C / min for distillation and kept warm for 3 h. During the experiment, the state change of solid NaOH and the time point when the solid disappeared were recorded. After the insulation was completed, the heating jacket was removed and the mixed liquid was cooled to a base agglomerate. The solid base was heated and dissolved and then transferred out to test the alkalinity. The liquid phase was transferred to a four-necked flask, the heating jacket was turned on and the temperature was slowly raised. The final heating temperature was controlled at 140°C. After the distillation was completed, the water content of isooctyl alcohol was tested. After gas chromatography, the residual amount of base in the octanol was 0.31 mg NaOH / g and the content of sodium isooctyl alcohol was 23.5%.

[0067] (2) Condensation of diisooctyl isooctylphosphonate: Accurately weigh 1 mol of diisooctyl phosphite intermediate prepared in Example 3 (actual effective amount 306.4 g), weigh 1.03 mol of sodium isooctyl alcohol (actual effective amount 156.56 g) prepared in step (1), add them all at once into a 2000 mL four-hole flask, turn on the electric heating jacket, and simultaneously turn on the vacuum pump, raise the temperature to 140°C, distill for 2 h, evaporate isooctyl alcohol, distill until no isooctyl alcohol is produced, remove the distillation apparatus, weigh 2.2 mol of chloroisooctane collected in Example 3, add it all at once into the flask, add a reflux apparatus to the flask, raise the temperature to 170°C, and start temperature control (pay attention to bumping), keep the temperature at 180°C for 4 h, and after the insulation is completed, cool the temperature to 90°C for distillation, replace the reflux apparatus with a distillation apparatus, and evaporate chloroisooctane; After the obtained material is cooled, 200 mL of pure water is added to dissolve the NaCl in the material, and the material is transferred to a 1000 mL conical funnel and allowed to stand for phase separation. After the water phase is discharged, the oil phase is transferred to a 1000 mL four-hole flask to distill out water and the front fraction first, and the collection flask is switched to carry out fine distillation of diisooctyl isooctylphosphonate at a temperature of 230 ° C. Distill until no material is discharged to obtain diisooctyl isooctylphosphonate, and its content is detected to be 94.8%.

[0068] (3) Preparation of P507 sodium salt: Add 1.6 mol of 46% sodium hydroxide solution and 1.0 mol of diisooctyl isooctylphosphonate into a 1000 mL four-hole flask, stir, and heat the contents. Open the distillation condenser, slowly increase the temperature, and evaporate isooctyl alcohol under normal pressure. After 1.5 hours, the liquid temperature rises to 130°C, then open the vacuum system, evaporate 50% of the isooctyl alcohol, and use the remaining isooctyl alcohol as a solvent to prevent the contents in the flask from becoming too viscous. At this time, stirring should be stopped in time.

[0069] After the isooctyl alcohol is evaporated, stop heating, turn off the vacuum, add 200 mL of water to the flask to dissolve, make sure to stir at 500 r / min until it is completely dissolved, start stirring, and after all the solid phase in the flask is dissolved, stop stirring, transfer to a 1000 mL conical flask, let it stand and then drain the water phase to obtain P507 sodium salt.

[0070] (4) P507 sodium salt was transferred to a four-necked flask, and 1.0 mol hydrochloric acid (mass concentration 34%) was added to acidify until the pH of the oil phase was 0.8, and then the acid water was discharged. Water was then added to stir and wash the mixture until the final pH of the P507 oil phase was 5. Finally, after washing, P507 was transferred to a four-necked flask, stirred and heated, and the condenser was turned on. Water and isooctyl alcohol were evaporated at 90°C (gas phase temperature) under a vacuum condition of -0.09 MPa. When the liquid temperature reached 145°C, the water ring vacuum pump was switched to a rotary vane vacuum pump. When the liquid temperature reached 180°C and the vacuum was -0.1 MPa, the fraction decreased significantly and the air temperature began to drop. The isooctyl alcohol distillation process was completed, and the heating was stopped, the mixture was vented, and the condenser and vacuum pump were stopped to obtain P507. Its content was detected to be 96.5%, and its yield was calculated to be 85.8%.

[0071] Comparative Example 1 A method for preparing a diisooctyl phosphite intermediate comprises the following steps: (1) Accurately weigh 1.0 mol PCl3 and place it in a 250 mL constant pressure funnel. Measure 3.1 mol isooctyl alcohol and place it in a 1000 mL four-hole flask. Add phosphorus trichloride to the isooctyl alcohol by submerged addition for reaction. The temperature of the liquid in the flask is maintained at 20 °C by controlling the drop rate to 1.0 mL / min and adding an ice-water bath. At the same time, turn on the water circulation vacuum pump to control the pressure at -0.020 MPa during the drop addition. During the vacuuming process, slowly add water to the constant pressure funnel on the HCl absorption device. The absorption liquid is collected in the bottom flask and the acidity is tested. The pressure remains unchanged and the temperature is maintained at 20 °C for 1.5 h to ensure that the materials are fully reacted. Some HCl is still dissolved in the obtained diisooctyl phosphite mixture.

[0072] (2) Deacidification of the diisooctyl phosphite mixture by alkali neutralization method: The diisooctyl phosphite mixture was transferred to a 1000 mL conical funnel, and the material was first washed with pure water to ensure that most of the HCl was dissolved in the water. The aqueous phase was discharged from the bottom, and a 10% mass concentration of NaOH solution was added to the conical funnel to adjust it to neutrality. The mixture was then washed with water three times, and the oil phase and the aqueous solution were separated until the acidity was below 3.33 mg NaOH / g, thereby obtaining a deacidified diisooctyl phosphite mixture.

[0073] (3) Distilling the deacidified diisooctyl phosphite mixed solution: the mixed solution was placed in a distillation flask, and the temperature was first slowly raised to 120°C at a rate of 2.0°C / min under -0.095 MPa. After the chloroisooctane was discharged, the temperature was further raised to 150°C for distillation, and the chloroisooctane was collected (the chloroisooctane content was 86.2%, the isooctyl alcohol content was 13.8%, and the yield was 93%). After separating the two, diisooctyl phosphite was collected. The gas chromatography detected its content and found it to be 88.5%. The yield was calculated to be 93%.

[0074] The prepared diisooctyl phosphite was subjected to nuclear magnetic resonance (NMR) P spectrum detection, and its NMR P spectrum is as follows: Figure 6 Its NMR data are shown in Table 5.

[0075] Table 5 NMR P spectrum data table

[0076] According to the data in Table 5 above, compared with the standard sample data in Table 1, the NMR P spectrum of the diisooctyl phosphite sample prepared in this comparative example shows additional signal peaks in the peak ranges of 10.96-9.41 and 8.43-6.92, with percentages of 2% and 1%. Compared with the NMR P spectrum of the standard sample, the monoester content is also 3%. Compared with the standard sample, the content and purity of the diisooctyl phosphite sample prepared in this comparative example are higher in impurity content and type than the standard sample.

[0077] Comparative Example 2 A method for preparing a diisooctyl phosphite intermediate comprises the following steps: (1) Accurately weigh 1.0 mol PCl3 and place it in a 250 mL constant pressure funnel. Measure 3.1 mol isooctanol and place it in a 1000 mL four-hole flask. PCl3 is directly added dropwise onto the surface of the isooctanol liquid phase. The dropping speed is controlled at 1.0 mL / min. An ice-water bath is added to maintain the liquid temperature in the flask at 20 °C. At the same time, a water circulation vacuum pump is turned on to control the pressure at -0.020 MPa during the dropping process. During the vacuuming process, water is slowly added to the constant pressure funnel on the HCl absorption device. The absorption liquid is collected in the bottom flask and the acidity is tested. The pressure remains unchanged and the temperature is maintained at 20 °C for 1.5 h to ensure that the materials are fully reacted. Some HCl is still dissolved in the obtained diisooctyl phosphite mixture.

[0078] (2) Deacidification of diisooctyl phosphite mixture by gas phase ammonia neutralization method: In a four-hole flask, a mixture of ammonia and nitrogen in a volume ratio of 1:9 is passed through a pressure regulator to control the gas flow rate to 1000 mL / min. In order to allow ammonia to fully react with HCl, it is introduced into the bottom of the four-hole flask through a porous catheter. Under stirring, the pH of the oil phase is detected with a 5.0-9.0 pH test paper. Based on the color of the test paper, it is preliminarily judged to be above 7, and the ventilation is stopped. Then, a positive pressure filter device (the filter medium is 108C type dense filter cloth) is used to filter out solid NH4Cl. If the solution is not clear, the filtering operation is repeated until the acidity is below 3.33 mgNaOH / g to obtain a deacidified diisooctyl phosphite mixture.

[0079] (3) Distilling the deacidified diisooctyl phosphite mixed solution: the mixed solution was placed in a distillation flask, and the temperature was first slowly raised to 120°C at a rate of 2.0°C / min under -0.095 MPa. After the chloroisooctane was discharged, the temperature was further raised to 150°C for distillation, and the chloroisooctane was collected (the chloroisooctane content was 83.7%, the isooctyl alcohol content was 16.3%, and the chloroisooctane yield was 90.0%). After separating the two, diisooctyl phosphite was collected. The gas chromatography detected its content and found it to be 96.1%. The yield was calculated to be 90.4%.

Claims

1. A method for preparing a diisooctyl phosphite intermediate, characterized in that: The following steps are involved: Phosphorus trichloride is added dropwise to isooctyl alcohol in a submerged manner for reaction, the dropping speed is controlled to be 1.0 mL / min~1.5 mL / min, the dropping pressure is controlled to be -0.020 MPa~-0.030 MPa, the reaction temperature is controlled to be 20°C~25°C, and the reaction time is 1 h~1.5 h to obtain a diisooctyl phosphite mixture, and the diisooctyl phosphite mixture is subjected to a gas phase ammonia neutralization method or a high vacuum HCl removal method to remove impurities, and the acidity is detected to be less than 3.33 mgNaOH / g, and chloroisooctane is continuously distilled out and collected to obtain chloroisooctane by-product, and finally diisooctyl phosphite is obtained.

2. The method for preparing a diisooctyl phosphite intermediate according to claim 1, wherein: The specific steps of the gas phase ammonia neutralization method are: introducing a mixed gas of ammonia and nitrogen into the diisooctyl phosphite mixture, stirring, controlling the gas flow rate to 800-1000 mL / min, until the acidity is below 3.33 mg NaOH / g, and then filtering until the filtrate is clear to obtain a deacidified mixed solution.

3. The method for preparing a diisooctyl phosphite intermediate according to claim 2, wherein: The volume ratio of ammonia to nitrogen is 1:9~2:

8.

4. The method for preparing a diisooctyl phosphite intermediate according to claim 1, wherein: The specific steps of the high vacuum HCl removal method are: maintaining the temperature of the diisooctyl phosphite mixture at 55°C to 65°C, using a negative pressure system, at a pressure of -0.090MPa to -0.095MPa, controlling the dropping speed to 3.0mL / min to 4.5mL / min, dripping through a thorn-shaped fractionation column until the acidity is below 3.33mgNaOH / g, and obtaining a deacidified mixed solution.

5. The method for preparing the diisooctyl phosphite intermediate according to claim 4, characterized in that: The negative pressure system comprises a constant pressure funnel, a thorn-shaped fractionation column, and a 2XZ-2 rotary vane vacuum pump.

6. The method for preparing a diisooctyl phosphite intermediate according to claim 1, wherein: The distillation is carried out at a pressure of -0.095MPa, firstly heating the temperature to 110°C~120°C at a speed of 2.0°C / min~3.0°C / min, until the chloroisooctane is discharged, and then continuing to heat the temperature to 130~150°C for distillation until no chloroisooctane is distilled out.

7. The method for preparing a diisooctyl phosphite intermediate according to claim 1, characterized in that: During the reaction of the diisooctyl phosphite mixture, the reaction temperature is controlled by an ice-water bath, and during the reaction, the hydrogen chloride gas generated during the reaction is absorbed by a hydrogen chloride absorption device.

8. Use of an intermediate in the preparation of P507, characterized in that: The intermediate is prepared by the preparation method of the diisooctyl phosphite intermediate according to any one of claims 1 to 7, and the application comprises the following steps: (1) Preparation of sodium isooctyl alcohol: heat isooctyl alcohol to 60-70°C, add solid sodium hydroxide and mix, continue heating to 130-150°C, keep warm for 2.5-3.5 hours, cool down until the alkali agglomerates, transfer the solid alkali after heating and dissolving; heat the liquid phase to 130-150°C at a rate of 2.0°C / min-3.0°C / min and distill. After completion, an isooctyl alcohol mixed liquid is obtained, and the isooctyl alcohol content is 20%-25%; (2) Condensation of diisooctyl isooctylphosphonate: Mix the diisooctyl phosphite intermediate with the sodium isooctyl alcohol mixed solution prepared in step (1), heat to 140°C-150°C for reaction until no isooctyl alcohol is distilled out, then add isooctane chloride collected in the preparation of diisooctyl phosphite intermediate, react at 180-190°C for 3-4h, first cool to 80-90°C and then start heating for distillation until no gas phase is produced, cool to room temperature, add water to dissolve, stand for phase separation, and purify the obtained organic phase at 230-240°C to obtain diisooctyl isooctylphosphonate; (3) Preparation of P507 sodium salt: Mix the prepared diisooctyl isooctylphosphonate with sodium hydroxide solution, heat to 120-130°C and stir, distill at atmospheric pressure for 1.5-2.5 hours, add water and stir at 500-1000 r / min until all dissolved, stop stirring, let stand and drain, and obtain P507 sodium salt; (4) Preparation of P507: Hydrochloric acid is added to the prepared sodium salt of P507 to acidify it so that the pH of the oil phase is 0.8-1.2, and then the water is drained and water is added to the oil phase to wash it until the pH of the oil phase is 4-5. The obtained oil phase is post-treated to obtain P507.

9. Use of the intermediate according to claim 8 in the preparation of P507, characterized in that: The mass concentration of the sodium hydroxide solution in step (3) is 46% to 48%; the mass concentration of the hydrochloric acid in step (4) is 34% to 36%.

10. Use of the intermediate according to claim 8 in the preparation of P507, characterized in that: The post-treatment step of step (4) is as follows: distilling the obtained oil phase at -0.090 MPa to -0.095 MPa and a gas phase temperature of 85°C to 90°C until no gas phase is generated, and continuing to raise the temperature to 160 to 180°C and distill at a vacuum degree of -0.1 MPa until the distillation vapor temperature begins to decrease, and then ending the distillation and dropping the temperature to room temperature.

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