Preparation method of 2-phosphonobutane-1, 2, 4-tricarboxylic acid

Abstract

The invention relates to a preparation method of 2-phosphonobutane-1, 2, 4-tricarboxylic acid, which comprises the following steps: carrying out hydrolysis reaction on 2-phosphonobutane-1, 2, 4-tricarboxylic acid pentamethyl ester and water in the presence of an acid catalyst to obtain the 2-phosphonobutane-1, 2, 4-tricarboxylic acid, the acid catalyst is selected from one or more of sulfuric acid loaded titanium dioxide, sulfuric acid loaded zirconium dioxide, a sulfuric acid loaded molecular sieve and a p-toluenesulfonic acid loaded molecular sieve. By adding the acid catalyst, the hydrolysis reaction time is shortened, the energy is saved, the consumption is reduced, the production efficiency is high, the yield is high, the purity is high, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and specifically to a method for preparing 2-phosphonobutane-1,2,4-tricarboxylic acid. Background Technology

[0002] 2-Butane-1,2,4-tricarboxylic acid (hereinafter referred to as PBTC) is a multifunctional water treatment agent, mainly used in industrial water treatment, with both scale inhibition and corrosion inhibition functions. Its core uses include: (1) Scale inhibition: circulating cooling water systems, field water injection systems, industrial boiler water treatment, high temperature and high hardness water; (2) Corrosion inhibition: forming a protective film on the metal surface to inhibit corrosion reaction, suitable for carbon steel pipes, heat exchangers, etc.; (3) Other industrial fields: cleaning agent: as a component to remove scale and deposits; textile dyes: improving dyeing quality and preventing post-treatment from affecting dye dispersion; petrochemicals: used for protection in oil extraction and production processes. The advantages of 2-Butane-1,2,4-tricarboxylic acid, such as high temperature resistance, chlorine oxidation resistance, low phosphorus content and environmental friendliness, make it a preferred agent in the field of water treatment.

[0003] Currently, some manufacturers of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) use a process that uses pentamethyl 2-phosphonobutane-1,2,4-tricarboxylic acid and water as raw materials without any catalyst. In this process, methanol aqueous solution is distilled off simultaneously with the hydrolysis reaction, and the entire process takes up to 50 hours. This process has the disadvantages of long reaction time and high energy consumption, which is not conducive to industrial production.

[0004] There is an urgent need to develop a method for preparing 2-phosphonobutane-1,2,4-tricarboxylic acid that can shorten reaction time, achieve energy saving and consumption reduction, and is more suitable for industrial production. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing 2-phosphonobutane-1,2,4-tricarboxylic acid, which has a short reaction time, saves energy and reduces consumption, and is suitable for industrial production.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows: This invention provides a method for preparing 2-phosphonobutane-1,2,4-tricarboxylic acid, the method comprising the following steps: 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester and water, in the presence of an acid catalyst, undergo a hydrolysis reaction to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; wherein the acid catalyst is selected from one or more of sulfuric acid-supported titanium dioxide, sulfuric acid-supported zirconium dioxide, sulfuric acid-supported molecular sieve, and p-toluenesulfonic acid-supported molecular sieve.

[0007] Preferably, the molar ratio of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester to water is 1:(5~6).

[0008] Preferably, the amount of acid catalyst added is 5 wt% to 20 wt% of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added, more preferably 5 wt% to 10 wt%.

[0009] Preferably, the reaction temperature of the hydrolysis reaction is 95~105℃.

[0010] Preferably, the hydrolysis reaction takes 3 to 10 hours, and more preferably 5 to 10 hours.

[0011] Preferably, the hydrolysis reaction is terminated when the content of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester in the hydrolysis reaction system is less than 0.5%.

[0012] Preferably, water is added to the hydrolysis reaction system when the temperature of the hydrolysis reaction system is 95°C.

[0013] Preferably, the mass ratio of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added to the amount of water added is 1:(0.5~1), more preferably 1:(0.6~0.7).

[0014] Preferably, while adding water, the methanol-water solution distilled from the hydrolysis reaction system is subjected to rectification.

[0015] Preferably, the hydrolysis reaction further includes a post-processing step.

[0016] Preferably, the post-processing includes: filtering.

[0017] Due to the adoption of the above technical solutions, the present invention has the following advantages compared with the prior art: This invention uses 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester and water as raw materials to prepare 2-phosphonobutane-1,2,4-tricarboxylic acid in the presence of an acid catalyst. By adding an acid catalyst, this invention shortens the hydrolysis reaction time, saves energy and reduces consumption, and has high production efficiency, high yield, and high purity, making it suitable for industrial production. Detailed Implementation

[0018] To make the technical solution and beneficial effects of the present invention more apparent and understandable, a detailed description is provided below by listing specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional experimental conditions. Unless otherwise specified, all reagents and raw materials used in this invention are commercially available.

[0019] This invention provides a method for preparing 2-phosphonobutane-1,2,4-tricarboxylic acid, the method comprising the following steps: 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester and water, in the presence of an acid catalyst, undergo a hydrolysis reaction to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; wherein the acid catalyst is selected from one or more of sulfuric acid-supported titanium dioxide, sulfuric acid-supported zirconium dioxide, sulfuric acid-supported molecular sieve, and p-toluenesulfonic acid-supported molecular sieve.

[0020] In some embodiments, the molar ratio of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester to water is 1:(5~6), for example, 1:5, 1:5.1, 1:5.2, 1:5.3, 1:5.4, 1:5.5, 1:5.6, 1:5.7, 1:5.8, 1:5.9, 1:6, etc.

[0021] In some embodiments, the molar ratio of the 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester to water is 1:(5.4~5.6).

[0022] In some embodiments, the molar ratio of the 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester to water is 1:5.5.

[0023] In some embodiments, the amount of acid catalyst added is 5 wt% to 20 wt% of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added, for example, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, etc.

[0024] In some embodiments, the amount of acid catalyst added is 5 wt% to 10 wt% of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added.

[0025] In some embodiments, the amount of acid catalyst added is 10 wt% of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added.

[0026] In some embodiments, the reaction temperature of the hydrolysis reaction is 95~105℃, such as 95℃, 96℃, 97℃, 98℃, 99℃, 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, etc.

[0027] In some embodiments, the reaction time of the hydrolysis reaction is 3 to 10 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.

[0028] In some embodiments, the hydrolysis reaction takes 5 to 10 hours.

[0029] In some embodiments, the hydrolysis reaction is terminated when the content of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester in the reaction system is less than 0.5%.

[0030] In some embodiments, water is added to the hydrolysis reaction system when the temperature of the hydrolysis reaction system is 95°C.

[0031] In some embodiments, the mass ratio of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added to the amount of water added is 1:(0.5~1), for example: 1:0.5, 1:0.6, 1:0.61, 1:0.62, 1:0.63, 1:0.64, 1:0.65, 1:0.66, 1:0.67, 1:0.68, 1:0.69, 1:0.7, 1:0.8, 1:0.9, 1:1, etc.

[0032] In some embodiments, the mass ratio of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added to the amount of water added is 1:(0.6~0.7).

[0033] In some embodiments, the methanol-water solution distilled from the hydrolysis reaction system is subjected to distillation simultaneously with the addition of water.

[0034] In some embodiments, the hydrolysis reaction is further followed by a post-processing step.

[0035] In some implementations, the post-processing includes filtering.

[0036] In some implementations, the filtration includes: vacuum filtration.

[0037] In some embodiments, the filtration is performed at 20-30°C.

[0038] In some embodiments, the post-processing step may further include adding deionized water.

[0039] In some embodiments, the 2-phosphonobutane-1,2,4-tricarboxylic acid satisfies one or more of (1) to (6): (1) The content of the active component (calculated as 2-phosphonobutane-1,2,4-tricarboxylic acid) is 50.0~52.0%; (2) Solid content is 53.0~57.0%; (3) Total phosphate (as PO4) 3- The content (calculated) is 17-19%; (4) Phosphate (in the form of PO4) 3- The content (calculated) is less than 0.2%; (5) Phosphites (as PO3) 3- The content (calculated) is less than 0.5%; (6) The pH value is 1.5~1.9; Where % represents the mass percentage.

[0040] In this invention, "room temperature" is 20~30℃.

[0041] In this invention, "%" represents the mass percentage.

[0042] The method of the present invention will be described below through specific embodiments. It should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0043] Example 1 Take a 500mL four-necked reaction flask, add 200g of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester (hereinafter referred to as: pentamethyl ester, 0.588mol) and 58g of water (3.234mol), the molar ratio of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester to water is 1:5.5. Add 20g of sulfuric acid-supported zirconium dioxide, start stirring and begin heating. When the T in the reaction system... 内 At 95℃, 130g of water was slowly added to the reaction flask, and timing was started simultaneously, maintaining the reaction system temperature between 95 and 105℃. Throughout the reaction, the material continuously evaporated from the system; the evaporated methanol-water solution was recovered by distillation, and the aqueous phase was recycled back into the reaction system. After 5 hours, samples were taken for controlled analysis until the remaining content of the pentacetic acid ester was detected to be below 0.5%, at which point the reaction endpoint was reached, heating was stopped, and timing was terminated, for a total of 6 hours. After the material cooled to room temperature, it was filtered to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; purity 95.67%, yield 98.50%.

[0044] Add an appropriate amount of deionized water to the obtained 2-phosphonobutane-1,2,4-tricarboxylic acid to adjust its solid content to 55%. After comprehensive quality testing, the PBTC active ingredient content was 50.25%, and the total phosphate content (as PO4) was... 3- The content of phosphate (calculated as PO4) was 17.8%, and the phosphate content (calculated as PO4) was 17.8%. 3- The content of phosphate (calculated as PO3) was 0.18%, and the phosphate content (calculated as PO3) was 0.18%. 3- The concentration (calculated) is 0.42%; the appearance is a pale yellow transparent liquid with a pH value of 1.7.

[0045] Example 2 Take a 500mL four-necked reaction flask, add 200g of pentazocine (0.588mol) and 58g of water (3.234mol), the molar ratio of pentazocine to water is 1:5.5. Add 20g of sulfuric acid-supported titanium dioxide, start stirring and heating. When the T value of the reaction system reaches a certain level... 内 At 95℃, 130g of water was slowly added to the reaction flask, and timing was started simultaneously, maintaining the reaction system temperature between 95 and 105℃. Throughout the reaction, the material in the system continuously evaporated, and the evaporated methanol-water solution was recovered by distillation, while the aqueous phase was recycled back into the reaction system. After 5 hours, samples were taken for centralized analysis until the remaining content of the pentacetic acid ester was detected to be below 0.5%, at which point the reaction endpoint was reached, heating was stopped, and timing was stopped, for a total of 8 hours. After the material cooled to room temperature, it was filtered to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; purity 94.58%, yield 97.20%.

[0046] Add an appropriate amount of deionized water to the obtained 2-phosphonobutane-1,2,4-tricarboxylic acid to adjust its solid content to 55%. After comprehensive quality testing, the PBTC active ingredient content was 51.5%, and the total phosphate content (as PO4) was... 3- The content of phosphate (calculated as PO4) was 18.4%, and the phosphate content (calculated as PO4) was 18.4%. 3- The content of phosphate (calculated as PO3) is 0.12%, and the phosphate content (calculated as PO3) is 0.12%. 3- The concentration (calculated) is 0.32%; the appearance is a pale yellow transparent liquid with a pH value of 1.7.

[0047] Example 3 Take a 500mL four-necked reaction flask, add 200g of pentacetic acid (0.588mol) and 58g of water (3.234mol), the molar ratio of pentacetic acid to water is 1:5.5. Add 20g of p-toluenesulfonic acid-supported molecular sieve, start stirring and heating. When the T value of the reaction system reaches a certain level... 内 At 95℃, 130g of water was slowly added to the reaction flask, and timing was started simultaneously, maintaining the reaction system temperature between 95 and 105℃. Throughout the reaction, the material in the system continuously distilled off; the distilled methanol-water solution was recovered by distillation, and the aqueous phase was recycled back into the reaction system. After 5 hours, samples were taken for centralized analysis until the remaining content of the raw material pentacetic acid was detected to be below 0.5%, at which point the reaction endpoint was reached, heating was stopped, and timing was stopped, for a total of 10 hours. After the material cooled to room temperature, it was filtered to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; purity 93.65%, yield 95.20%.

[0048] Add an appropriate amount of deionized water to the obtained 2-phosphonobutane-1,2,4-tricarboxylic acid to adjust its solid content to 55%. After comprehensive quality testing, the PBTC active ingredient content was 50.8%, and the total phosphate content (as PO4) was... 3- The content of phosphate (calculated as PO4) was 18.1%, and the phosphate content (calculated as PO4) was 18.1%. 3- The content of phosphate (calculated as PO3) was 0.13%, and the content of phosphate (calculated as PO3) was 0.13%. 3- The concentration (calculated) is 0.38%; the appearance is a colorless and transparent liquid with a pH of 1.8.

[0049] Example 4 Take a 500mL four-necked reaction flask, add 200g of pentazocine (0.588mol) and 58g of water (3.234mol), the molar ratio of pentazocine to water is 1:5.5. Add 20g of sulfuric acid-supported molecular sieve, start stirring and heating. When the T value of the reaction system reaches a certain level... 内 At 95℃, 130g of water was slowly added to the reaction flask, and timing was started simultaneously, maintaining the reaction system temperature between 95 and 105℃. Throughout the reaction, the material in the system continuously evaporated, and the evaporated methanol-water solution was recovered by distillation, while the aqueous phase was recycled back into the reaction system. After 5 hours, samples were taken for centralized analysis until the remaining content of the pentacetic acid ester was detected to be below 0.5%, at which point the reaction endpoint was reached, heating was stopped, and timing was terminated, for a total of 8 hours. After the material cooled to room temperature, it was filtered to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; purity 96.32%, yield 98.90%.

[0050] Add an appropriate amount of deionized water to the obtained 2-phosphonobutane-1,2,4-tricarboxylic acid to adjust its solid content to 55%. After comprehensive quality testing, the PBTC active ingredient content was 51.35%, and the total phosphate content (as PO4) was... 3- The content of phosphate (calculated as PO4) was 17.1%, and the phosphate content (calculated as PO4) was 17.1%. 3- The content of phosphate (calculated as PO3) was 0.11%, and the phosphate content (calculated as PO3) was 0.11%. 3- The concentration (calculated) is 0.32%; the appearance is a colorless and transparent liquid with a pH value of 1.8.

[0051] Comparative Example 1 Take a 500mL four-necked reaction flask, add 200g of pentazocine (0.588mol) and 58g of water (3.234mol), the molar ratio of pentazocine to water is 1:5.5. Add 6g of sulfuric acid-supported molecular sieve, start stirring and heating. When the T value of the reaction system reaches a certain level... 内At 95℃, 130g of water was slowly added to the reaction flask, and timing was started simultaneously, maintaining the reaction system temperature between 95 and 105℃. Throughout the reaction, the material in the system continuously distilled off, and the distilled methanol-water solution was recovered by distillation, while the aqueous phase was recycled back into the reaction system. After 5 hours, samples were taken for centralized analysis until the remaining content of the pentacetic acid ester was detected to be below 0.5%, at which point the reaction endpoint was reached, heating was stopped, and timing was terminated, for a total of 24 hours. After the material cooled to room temperature, it was filtered to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; purity 92.13%, yield 93.56%.

[0052] Add an appropriate amount of deionized water to the obtained 2-phosphonobutane-1,2,4-tricarboxylic acid to adjust its solid content to 55%. After comprehensive quality testing, the PBTC active ingredient content was 48.72%, and the total phosphate content (as PO4) was... 3- The content of phosphate (calculated as PO4) was 16.9%, and the phosphate content (calculated as PO4) was 16.9%. 3- The content of phosphate (calculated as PO3) was 0.21%, and the phosphate content (calculated as PO3) was 0.21%. 3- The concentration (calculated) is 0.29%; the appearance is a colorless liquid with a pH value of 1.8.

[0053] Comparative Example 2 Take a 500mL four-necked reaction flask, add 200g of pentacetic acid (0.588mol) and 58g of water (3.234mol), the molar ratio of pentacetic acid to water is 1:5.5. Add 20g of solid catalyst p-toluenesulfonic acid, start stirring and heating. When the T value of the reaction system reaches a certain level... 内 At 95℃, 130g of water was slowly added to the reaction flask, and timing was started simultaneously, maintaining the reaction system temperature between 95 and 105℃. Throughout the reaction, the material continuously evaporated from the system. The evaporated methanol-water solution was recovered by distillation, and the aqueous phase was recycled back into the reaction system. After 5 hours, samples were taken for centralized analysis until the remaining content of the pentacetic acid ester was detected to be below 0.5%, at which point the reaction endpoint was reached, heating was stopped, and timing was stopped, for a total of 20 hours. After the material cooled to room temperature, it was filtered to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; purity 93.32%, yield 94.90%.

[0054] Add an appropriate amount of deionized water to the obtained 2-phosphonobutane-1,2,4-tricarboxylic acid to adjust its solid content to 55%. After comprehensive quality testing, the PBTC active ingredient content was 48.96%, and the total phosphate content (as PO4) was... 3 The phosphate content (calculated as PO4) was 16.3%, and the phosphate content (calculated as PO4) was 16.3%. 3 The content of phosphate (calculated as PO3) was 0.13%, and the phosphate content (calculated as PO3) was 0.13%. 3 The concentration (calculated) is 0.35%; the appearance is a colorless and transparent liquid with a pH value of 1.7.

[0055] Comparative Example 3 Take a 500mL four-necked reaction flask, add 200g of pentazocine (0.588mol) and 58g of water (3.234mol), the molar ratio of pentazocine to water is 1:5.5. Add 20g of sulfuric acid as a catalyst, start stirring and heating. When the T value of the reaction system reaches a certain level... 内 At 95℃, 130g of water was slowly added to the reaction flask, and timing was started simultaneously, maintaining the reaction system temperature between 95 and 105℃. Throughout the reaction, materials continuously evaporated from the system. The evaporated methanol-water solution was recovered by distillation, and the aqueous phase was recycled back into the reaction system. After 5 hours, samples were taken for centralized analysis until the residual content of the raw material pentacetic acid was detected to be below 0.5%, at which point the reaction endpoint was reached, heating was stopped, and timing was terminated, for a total of 8 hours. After the materials cooled to room temperature, they were filtered to obtain a mixture of 2-phosphonobutane-1,2,4-tricarboxylic acid and sulfuric acid. The residual sulfuric acid was an impurity, which did not meet market requirements, product quality standards, and was unsuitable for industrial production.

[0056] Comparative Example 4 Take a 500mL four-necked reaction flask, add 200g of pentazocine (0.588mol) and 58g of water (3.234mol), the molar ratio of pentazocine to water is 1:5.5. Add 20g of hydrochloric acid as a catalyst, start stirring and heating. When the T value of the reaction system reaches a certain level... 内 At 95℃, 130g of water was slowly added to the reaction flask, and timing was started simultaneously, maintaining the reaction system temperature at 95~105℃. Throughout the reaction, materials continuously evaporated from the system. The evaporated methanol-water solution was recovered by distillation, and the aqueous phase was recycled back into the reaction system. After 5 hours, samples were taken for centralized analysis until the residual content of the raw material pentacetic acid was detected to be below 0.5%, at which point the reaction endpoint was reached, heating was stopped, and timing was stopped, for a total of 20 hours. After the materials cooled to room temperature, they were filtered to obtain a mixture of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydrochloric acid, and a small amount of chloromethane. The hydrochloric acid and the small amount of chloromethane residue were impurities, which did not meet market requirements, did not meet product quality standards, and were unsuitable for industrial production.

[0057] According to standard HG / T 3662-2010, the product quality indicators of the water treatment agent PBTC prepared in Examples 1-4 above were measured as follows: PBTC active component content 50.0-52.0%, solid content 53.0-57.0%, and total phosphate content (as PO4). 3- The phosphate content (calculated as PO4) is 17-19%, and the phosphate content (calculated as PO4) is 17-19%. 3- The content of phosphate (calculated as PO3) is less than 0.2%, and the phosphate content (calculated as PO3) is less than 0.2%. 3-The concentration (calculated) is less than 0.5%, the pH value is 1.5~1.9, and the appearance is a colorless to pale yellow transparent liquid, which meets the product quality standards.

[0058] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of the invention that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of the present invention and do not limit the scope of protection of this patent.

Claims

1. A method for preparing 2-phosphonobutane-1,2,4-tricarboxylic acid, characterized in that, The preparation method includes the following steps: 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester and water, in the presence of an acid catalyst, undergo a hydrolysis reaction to obtain 2-phosphonobutane-1,2,4-tricarboxylic acid; the acid catalyst is selected from one or more of sulfuric acid-supported titanium dioxide, sulfuric acid-supported zirconium dioxide, sulfuric acid-supported molecular sieve and p-toluenesulfonic acid-supported molecular sieve.

2. The preparation method according to claim 1, characterized in that, The molar ratio of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester to water is 1:(5~6).

3. The preparation method according to claim 1, characterized in that, The amount of acid catalyst added is 5 wt% to 20 wt% of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added, preferably 5 wt% to 10 wt%.

4. The preparation method according to claim 1, characterized in that, The reaction temperature for the hydrolysis reaction is 95~105℃.

5. The preparation method according to claim 1, characterized in that, The reaction time for the hydrolysis reaction is 3 to 10 hours, preferably 5 to 10 hours.

6. The preparation method according to claim 1, characterized in that, The hydrolysis reaction is terminated when the content of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester is below 0.5% in the reaction system.

7. The preparation method according to claim 4, characterized in that, When the temperature of the hydrolysis reaction system is 95°C, water is added to the hydrolysis reaction system.

8. The preparation method according to claim 7, characterized in that, The mass ratio of the amount of 2-phosphonobutane-1,2,4-tricarboxylic acid pentamethyl ester added to the amount of water added is 1:(0.5~1), preferably 1:(0.6~0.7).

9. The preparation method according to claim 7, characterized in that, While adding water, the methanol-water solution distilled from the hydrolysis reaction system is subjected to rectification.

10. The preparation method according to claim 1, characterized in that, The hydrolysis reaction further includes a post-processing step; Preferably, the post-processing includes: filtering.