Preparation process of 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester root inhibitor

Abstract

The invention relates to the technical field of chemical synthesis, and provides a preparation process of a 2-(4-chloro-2-methylphenoxy)-polyethylene glycol propionate root inhibitor, which comprises the following steps: S1, adding 4-chloro-2-methylphenol and potassium hydroxide into absolute ethyl alcohol, and stirring to obtain a product 1; s2, adding the product 1 and methyl 2-bromopropionate into anhydrous DMF, heating and refluxing, pouring into water at 0-4 DEG C, carrying out suction filtration, washing, adding into absolute ethyl alcohol, stirring, adding sodium hydroxide, heating and refluxing at 80-85 DEG C for 2-4 hours, recovering the room temperature, adjusting the pH value to 2-3, and carrying out suction filtration and washing to obtain a product 2; and S3, adding the product 2, PEG-200, a catalyst and a polymerization inhibitor into toluene, heating, stirring, filtering, recovering the catalyst, taking an organic phase, adding a sodium bicarbonate aqueous solution, and removing water and toluene to obtain the 2-(4-chloro-2-methylphenoxy)-polyethylene glycol propionate. The 2-(4-chloro-2-methylphenoxy)-polyethylene glycol propionate obtained by the preparation process provided by the invention has the characteristic of high yield, and the catalyst is easy to separate and low in corrosivity.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and in particular to a preparation process of a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. Background Technology

[0002] With the promotion of green building and sponge city concepts, greening forms such as planted roofs and roof gardens are becoming increasingly popular. The strong penetrating power of plant roots can damage waterproofing layers, leading to leakage problems. Therefore, root inhibitors have become a key functional additive in waterproofing systems. Aryloxycarboxylic acid ester root inhibitors, such as polyethylene glycol 2-(4-chloro-2-methylphenoxy)propionate, octyl (R)-2-(4-chloro-2-methylphenoxy)propionate, and 2-methyl-4-chloropropionate-polyethylene glycol ester, inhibit the transport of auxin in roots and interfere with cell growth through their aryloxycarboxylic acid active groups. They have the advantages of low toxicity, environmental friendliness, and high root-blocking efficiency, and their synthesis process has received widespread attention in recent years.

[0003] Polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid (CAS No.: 144768-02-5) is widely used as a chemical root inhibitor due to its superior root-barrier properties, biocompatibility, material compatibility, and long-lasting effect. It protects the waterproof structure by interfering with the growth and metabolism of plant roots, inhibiting root extension towards the waterproof layer. The esterification reaction in the preparation process of polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid is crucial to the yield of the target product and often requires the addition of a catalyst to improve the yield. Currently, commonly used catalysts are concentrated sulfuric acid or p-toluenesulfonic acid. However, concentrated sulfuric acid is highly corrosive, and p-toluenesulfonic acid poses a residue risk, neither of which meets the requirements for long-term industrial applications.

[0004] Patent CN 119241360 A discloses a method for preparing (R)2-(4-chloro-2-methylphenoxy)propionate isooctyl ester root inhibitor, comprising the following steps: L-2-chloropropionic acid and o-cresol undergo a condensation reaction under the promotion of an alkali to obtain (R)2-methylphenoxypropionic acid; (R)2-methylphenoxypropionic acid and isooctyl alcohol (2-ethylhexanol) undergo an esterification reaction under the action of a catalyst to obtain (R)2-methylphenoxypropionate isooctyl ester; (R)2-methylphenoxypropionate isooctyl ester is chlorinated by a chlorinating agent to obtain (R)2-(4-chloro-2-methylphenoxy)propionate isooctyl ester. Although the synthetic route is novel and the product yield is high and of good quality, the catalyst used in this preparation method is still one or more of concentrated sulfuric acid, phosphoric acid, p-toluenesulfonic acid, and benzenesulfonic acid, which does not solve the problem of corrosion or residue that is difficult to handle.

[0005] Therefore, there is an urgent need in the market for a preparation process of polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor, which has an easy-to-separate catalyst with low corrosivity and excellent yield of the target product. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention prepares a 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester root inhibitor using 4-chloro-2-methylphenol, potassium hydroxide, methyl 2-bromopropionate, and PEG-200 as raw materials. A catalyst is designed to be added in the esterification stage of step S3, which avoids the problems of high corrosivity or easy residue of existing catalysts, and makes the prepared 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester have a high yield.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a process for preparing a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor, comprising the following steps: S1. Add 4-chloro-2-methylphenol and potassium hydroxide to anhydrous ethanol and stir to obtain product 1 for later use. S2. Add product 1 from step S1 and methyl 2-bromopropionate to anhydrous DMF, heat under reflux at 90-100℃ for 2-3 hours, then pour into water at 0-4℃, filter, wash, add to anhydrous ethanol, stir, add sodium hydroxide, heat under reflux at 80-85℃ for 2-4 hours, return to room temperature, add dilute hydrochloric acid to adjust pH to 2-3, filter, wash to obtain product 2 for later use. S3. Add product 2, PEG-200, catalyst and polymerization inhibitor from step S2 to toluene, stir at 95-100℃ for 4-5 hours, filter while hot, recover the catalyst, take the organic phase, first add sodium bicarbonate aqueous solution, then remove water with anhydrous sodium sulfate, and finally remove toluene by vacuum distillation to obtain 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester.

[0008] The mass ratio of 4-chloro-2-methylphenol to the polymerization inhibitor is 1:(0.0008-0.0012).

[0009] In some embodiments of the present invention, in step S1, the molar ratio of 4-chloro-2-methylphenol to potassium hydroxide is 1:(1-1.3).

[0010] Preferably, in step S1, the molar ratio of 4-chloro-2-methylphenol to potassium hydroxide is 1:1.2.

[0011] In some embodiments of the present invention, the molar ratio of 4-chloro-2-methylphenol to methyl 2-bromopropionate is 1:(1.2-1.6).

[0012] Preferably, the molar ratio of 4-chloro-2-methylphenol to methyl 2-bromopropionate is 1:1.5.

[0013] In some embodiments of the present invention, the molar ratio of 4-chloro-2-methylphenol to PEG-200 is (2-2.3):1.

[0014] Preferably, the molar ratio of 4-chloro-2-methylphenol to PEG-200 is 2.1:1.

[0015] In some embodiments of the present invention, the mass ratio of 4-chloro-2-methylphenol to catalyst is 1:(0.04-0.07).

[0016] Preferably, the mass ratio of 4-chloro-2-methylphenol to the catalyst is 1:0.05.

[0017] In some embodiments of the present invention, the method for preparing the catalyst includes the following steps: (1) Mix epoxy resin with polyethylene glycol 1000 and polyethylene glycol 2000, add diethylenetriamine, react at 65-75℃ for 2.5-3.5h, wash, dry and soak in tetraethyl orthosilicate for 3-4h, then place in an ammonia atmosphere at 45-55℃ for 11-13h, dry and calcine to obtain macroporous silica material for later use; (2) Add the macroporous silica material from step (1) into ZrOCl2 aqueous solution, soak it, take it out and add it into ammonia water, soak it for 9-11 hours, add Span 20 and n-hexane, stir, calcine, and obtain the product for later use. (3) Add the product of step (2) into an aqueous sulfuric acid solution, soak it, take it out and dry it, and calcine it at 550-600℃ to obtain the catalyst.

[0018] In some embodiments of the present invention, in step (1), the mass ratio of epoxy resin to polyethylene glycol 1000 and polyethylene glycol 2000 is 1:(1.1-1.3):(0.7-1).

[0019] In some embodiments of the present invention, in step (2), the ratio of macroporous silica material, Zr element in ZrOCl2 aqueous solution, and Span 20 is 1g:(0.0015-0.003)mol:(0.1-0.3)g.

[0020] In some embodiments of the present invention, in step (3), the product and SO4 2- The ratio is 1g:(0.013-0.02)mol.

[0021] The commonly used catalysts in the synthesis of polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitors are concentrated sulfuric acid or p-toluenesulfonic acid. However, concentrated sulfuric acid is highly corrosive, p-toluenesulfonic acid poses a residue risk, and SO4... 2- ZrO2 solid catalysts have advantages such as easy separation and no corrosion, and their acid strength and reactivity are also superior. However, they still have defects such as small specific surface area and poor stability, which limit their industrial application.

[0022] The applicant first used epoxy resin, polyethylene glycol of different molecular weights, and diethylenetriamine as raw materials to obtain a polymeric framework structure. The use of polyethylene glycol of different molecular weights in the network voids allows the framework structure to possess both large and small pore sizes. Furthermore, tetraethyl orthosilicate is fully diffused into the polymeric framework structure to obtain macroporous silica material. This allows Zr(OH)4, the product of subsequent ZrOCl2 hydrolysis, to be uniformly deposited on its surface, thereby effectively improving the specific surface area and stability of the catalyst and resulting in a more uniform distribution of catalytic active sites, which is beneficial to the catalytic performance. Furthermore, the applicant introduced Span 20 after Zr(OH)4 deposition in the macroporous silica material. This prevents Zr(OH)4 agglomeration, and its hydrophobic long carbon chain structure can encapsulate the aforementioned material, protecting ZrO2 during calcination and leaving a mesoporous structure during the subsequent calcination of the catalyst, thus allowing SO42- to pass through. 2- It is easier to diffuse to the ZrO2 active sites and bind to them, thus making the overall effect of the catalyst better.

[0023] In some embodiments of the present invention, the yield of the polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid is not less than 95%.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides a process for preparing 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester root inhibitor. 4-chloro-2-methylphenol, potassium hydroxide, methyl 2-bromopropionate and PEG-200 are used as raw materials. The synthesis steps and reaction conditions of the process are optimized and a catalyst is designed to be added. This avoids the problems of high corrosivity or easy residue of existing catalysts and makes the prepared 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester have a high yield.

[0025] (2) This invention designs a catalyst for the esterification reaction in step S3 of the synthesis process of polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. First, epoxy resin, polyethylene glycol of different molecular weights, and diethylenetriamine are used as raw materials to obtain a polymer framework structure. Tetraethyl orthosilicate is introduced to obtain macroporous silica material, allowing Zr(OH)4 from subsequent ZrOCl2 hydrolysis to be uniformly deposited on its surface, thereby effectively improving the specific surface area and stability of the catalyst. Furthermore, after Zr(OH)4 is deposited on the macroporous silica material, the applicant introduces Span 20 to prevent SO4 from forming. 2- It is easier to diffuse to the ZrO2 active site and bind to it, thereby improving the overall effect of the catalyst and increasing the yield of polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid.

[0026] (3) The yield of 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester obtained by the preparation process of the present invention is not less than 95%, which has the characteristic of high yield. Detailed Implementation

[0027] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0028] In the following examples, except for the catalyst, all other compound monomers and related reagents used can be purchased from the market. Among them, the epoxy resin is bisphenol A type epoxy resin E-51.

[0029] Preparation Example 1 The synthesis method of catalyst A includes the following steps: (1) Mix 16g of epoxy resin, 18g of polyethylene glycol 1000 and 14g of polyethylene glycol 2000, add 4g of diethylenetriamine, react at 70°C for 3h, wash with deionized water, dry at 60°C for 2h, soak in 150g of tetraethyl orthosilicate for 4h, then place in an ammonia atmosphere at 50°C for 12h, dry at 60°C for 2h, and calcine at 750°C for 1.5h with a heating rate of 5°C / min to obtain macroporous silica material for later use; (2) Add 10g of macroporous silica material from step (1) to 100ml of 0.2mol / L ZrOCl2 aqueous solution and soak for 4h. After taking it out, add 20ml of 28wt% ammonia water and soak for 10h. Add 2g of Span 20 and 50ml of n-hexane, stir for 1h, and calcine at 550℃ for 2h to obtain the product for later use. (3) Add 10g of the product from step (2) to 80ml of 2mol / L sulfuric acid aqueous solution, soak for 2h, take it out and dry at 100℃ for 4h, and calcine at 550℃ for 3h to obtain catalyst A.

[0030] Preparation Example 2 Catalyst B is implemented in the same way as catalyst A, except that in step (1), polyethylene glycol 2000 is replaced by an equal amount of polyethylene glycol 1000.

[0031] Preparation Example 3 Catalyst C is implemented in the same way as catalyst A, except that in step (1), polyethylene glycol 1000 is replaced by an equal amount of polyethylene glycol 2000.

[0032] Preparation Example 4 Catalyst D is implemented in the same way as catalyst A, except that the volume of the ZrOCl2 aqueous solution in step (2) is replaced with 50 ml.

[0033] Preparation Example 5 Catalyst E is implemented in the same way as catalyst A, except that the mass of Span 20 in step (2) is replaced with 0.8g.

[0034] Preparation Example 6 Catalyst F is implemented in the same way as catalyst A, except that the volume of sulfuric acid aqueous solution in step (3) is replaced with 50 ml.

[0035] Example 1 A process for preparing a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor includes the following steps: S1. Add 0.1 mol of 4-chloro-2-methylphenol and 0.12 mol of potassium hydroxide to 150 ml of anhydrous ethanol and stir for 30 min to obtain product 1 for later use. S2. Add product 1 from step S1 and 0.15 mol of methyl 2-bromopropionate to 60 ml of anhydrous DMF, heat under reflux at 95°C for 2.5 h, pour into 250 ml of 0°C water, filter, wash with 0°C water, add to 100 ml of anhydrous ethanol, stir for 30 min, add 6 g of sodium hydroxide, heat under reflux at 83°C for 3 h, restore to room temperature, add dilute hydrochloric acid to adjust pH=2.5, filter, wash with 0°C water to obtain product 2 for later use. S3. Add product 2 from step S2, 0.048 mol PEG-200, 0.7 g catalyst A and 0.01 g hydroquinone to 80 ml toluene, stir at 95 °C for 5 h, filter while hot, recover the catalyst, take the organic phase, first add 5 wt% sodium bicarbonate aqueous solution to pH=8, then remove water with anhydrous sodium sulfate, and finally remove toluene by vacuum distillation to obtain 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester.

[0036] Example 2 A process for preparing a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor includes the following steps: S1. Add 0.1 mol of 4-chloro-2-methylphenol and 0.1 mol of potassium hydroxide to 150 ml of anhydrous ethanol and stir for 30 min to obtain product 1 for later use. S2. Add product 1 from step S1 and 0.12 mol of methyl 2-bromopropionate to 60 ml of anhydrous DMF, heat under reflux at 90°C for 3 h, pour into 250 ml of 0°C water, filter, wash with 0°C water, add to 100 ml of anhydrous ethanol, stir for 30 min, add 6 g of sodium hydroxide, heat under reflux at 80°C for 4 h, return to room temperature, add dilute hydrochloric acid to adjust pH=2.5, filter, wash with 0°C water to obtain product 2 for later use. S3. Add product 2 from step S2, 0.044 mol PEG-200, 0.06 g catalyst A, and 0.01 g hydroquinone to 80 ml toluene, stir at 95 °C for 5 h, filter while hot, recover the catalyst, take the organic phase, first add 5 wt% sodium bicarbonate aqueous solution to pH=8, then remove water with anhydrous sodium sulfate, and finally remove toluene by vacuum distillation to obtain 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester.

[0037] Example 3 A process for preparing a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor includes the following steps: S1. Add 0.1 mol of 4-chloro-2-methylphenol and 0.13 mol of potassium hydroxide to 150 ml of anhydrous ethanol and stir for 30 min to obtain product 1 for later use. S2. Add product 1 from step S1 and 0.16 mol of methyl 2-bromopropionate to 60 ml of anhydrous DMF, heat under reflux at 100°C for 2 h, pour into 250 ml of 0°C water, filter, wash with 0°C water, add to 100 ml of anhydrous ethanol, stir for 30 min, add 6 g of sodium hydroxide, heat under reflux at 85°C for 2 h, return to room temperature, add dilute hydrochloric acid to adjust pH=2.5, filter, wash with 0°C water to obtain product 2 for later use. S3. Add product 2 from step S2, 0.05 mol PEG-200, 0.9 g catalyst A and 0.01 g hydroquinone to 80 ml toluene, stir at 95 °C for 5 h, filter while hot, recover the catalyst, take the organic phase, first add 5 wt% sodium bicarbonate aqueous solution to pH=8, then remove water with anhydrous sodium sulfate, and finally remove toluene by vacuum distillation to obtain 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester.

[0038] Example 4 This embodiment provides a preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. The specific implementation method is the same as in Example 1, except that the mass of catalyst A is replaced with 0.2g.

[0039] Example 5 This embodiment provides a preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. The specific implementation method is the same as in Example 1, except that the mass of catalyst A is replaced with 2g.

[0040] Example 6 This embodiment provides a preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. The specific implementation method is the same as in Example 1, except that catalyst B replaces catalyst A in an equal amount.

[0041] Example 7 This embodiment provides a preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. The specific implementation method is the same as in Example 1, except that catalyst A is replaced by catalyst C in an equal amount.

[0042] Example 8 This embodiment provides a preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. The specific implementation method is the same as in Example 1, except that catalyst D replaces catalyst A in an equal amount.

[0043] Example 9 This embodiment provides a preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. The specific implementation method is the same as in Example 1, except that catalyst A is replaced by catalyst E in an equal amount.

[0044] Example 10 This embodiment provides a preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. The specific implementation method is the same as in Example 1, except that catalyst F replaces catalyst A in an equal amount.

[0045] Example 11 This embodiment provides a preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor. The specific implementation method is the same as in Example 1, except that commercially available conventional SO4 is used. 2- / ZrO2 solid catalyst replaces catalyst A in equal amounts.

[0046] SO4 2- The ZrO2 solid catalyst was purchased from Qiyuan (Guangdong) Pharmaceutical & Chemical Co., Ltd.

[0047] Performance testing The yield of 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester described in Examples 1-11 above was tested, and the test results are shown in Table 1.

[0048] The yield of polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid was determined by HPLC.

[0049] Table 1 As shown in Table 1, the 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester root inhibitors in Examples 1-3 of this invention exhibit high overall yields. Specifically, Examples 4-5 altered the amount of catalyst A, resulting in poor promotion of the S3 esterification reaction in the preparation process of the 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester root inhibitor, leading to a decrease in yield. Examples 6-10 altered the proportions of key components in catalyst synthesis—macroporous silica, Span 20, and active ingredients—resulting in varying degrees of decrease in the catalyst's specific surface area, catalytic activity, and stability, leading to a poorer yield of 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester. Example 11 used commercially available conventional SO4. 2- When catalyst A was replaced by ZrO2 solid catalyst in equal amounts, the yield of the prepared 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol root inhibitor was found to be poor.

[0050] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A preparation process for a polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor, characterized in that, Includes the following steps: S1. Add 4-chloro-2-methylphenol and potassium hydroxide to anhydrous ethanol and stir to obtain product 1 for later use. S2. Add product 1 from step S1 and methyl 2-bromopropionate to anhydrous DMF, heat under reflux at 90-100℃ for 2-3 hours, then pour into water at 0-4℃, filter, wash, add to anhydrous ethanol, stir, add sodium hydroxide, heat under reflux at 80-85℃ for 2-4 hours, return to room temperature, add dilute hydrochloric acid to adjust pH to 2-3, filter, wash to obtain product 2 for later use. S3. Add product 2, PEG-200, catalyst and polymerization inhibitor from step S2 to toluene, stir at 95-100℃ for 4-5 hours, filter while hot, recover the catalyst, take the organic phase, first add sodium bicarbonate aqueous solution, then remove water with anhydrous sodium sulfate, and finally remove toluene by vacuum distillation to obtain 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester.

2. The preparation process of the 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester root inhibitor according to claim 1, characterized in that, In step S1, the molar ratio of 4-chloro-2-methylphenol to potassium hydroxide is 1:(1-1.3).

3. The preparation process of the 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester root inhibitor according to claim 1, characterized in that, The molar ratio of 4-chloro-2-methylphenol to methyl 2-bromopropionate is 1:(1.2-1.6).

4. The preparation process of the polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor according to claim 1, characterized in that, The molar ratio of 4-chloro-2-methylphenol to PEG-200 is (2-2.3):

1.

5. The preparation process of the polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor according to claim 1, characterized in that, The mass ratio of 4-chloro-2-methylphenol to catalyst is 1:(0.04-0.07).

6. The preparation process of the polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor according to claim 1, characterized in that, The catalyst preparation method in step S3 includes the following steps: (1) Mix epoxy resin with polyethylene glycol 1000 and polyethylene glycol 2000, add diethylenetriamine, react at 65-75℃ for 2.5-3.5h, wash, dry and soak in tetraethyl orthosilicate for 3-4h, then place in an ammonia atmosphere at 45-55℃ for 11-13h, dry and calcine to obtain macroporous silica material for later use; (2) Add the macroporous silica material from step (1) into ZrOCl2 aqueous solution, soak it, take it out and add it into ammonia water, soak it for 9-11 hours, add Span 20 and n-hexane, stir, calcine, and obtain the product for later use. (3) Add the product of step (2) into an aqueous sulfuric acid solution, soak it, take it out and dry it, and calcine it at 550-600℃ to obtain the catalyst.

7. The preparation process of the polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor according to claim 6, characterized in that, In step (1), the mass ratio of epoxy resin to polyethylene glycol 1000 and polyethylene glycol 2000 is 1:(1.1-1.3):(0.7-1).

8. The preparation process of the polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor according to claim 6, characterized in that, In step (2), the ratio of Zr element in macroporous silica material and ZrOCl2 aqueous solution to Span 20 is 1g: (0.0015-0.003)mol: (0.1-0.3)g.

9. The preparation process of the polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor according to claim 6, characterized in that, In step (3), the product and SO4 2- The ratio is 1g:(0.013-0.02)mol.

10. The preparation process of the polyethylene glycol 2-(4-chloro-2-methylphenoxy)-propionic acid root inhibitor according to any one of claims 1-9, characterized in that, The yield of the 2-(4-chloro-2-methylphenoxy)-propionic acid polyethylene glycol ester is not less than 95%.

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