Circulating preparation method of imazamox soluble salt

Abstract

The invention belongs to the field of pesticides, and particularly relates to a preparation method of imazamox soluble salt. The preparation method of the imazamox soluble salt comprises the following steps: adding a reaction medium into a reaction kettle, heating, adding an imazamox active compound, and starting stirring; slowly adding a reactive alkali, reacting for 1-3 hours, stopping heating, adding an extraction solvent, and continuously stirring for 0.5-2 hours; and centrifugally filtering, separating filtrate and solid, and drying the solid to obtain the imazamox soluble salt. Through optimization, the recovery rate of the imazamox soluble salt can reach 97.3%. The preparation method also comprises the following steps: adding ionic liquid into the separated filtrate, heating, extracting, rectifying and separating the reaction medium and the extracting solvent to realize cyclic utilization.

Description

Technical Field

[0001] The present invention belongs to the field of pesticides, and particularly relates to a cyclic preparation method of imazamox soluble salt. Background Art

[0002] 2-(4-Isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-5-methoxymethylnicotinic acid (CAS: 114311-32-9) is a broad-spectrum and highly efficient imidazolinone herbicide. Its mechanism of action inhibits the acetohydroxyacid synthase (AHAS) related to the synthesis of three essential branched-chain amino acids - valine, leucine, and isoleucine in plants. By reducing the above three amino acids, the synthesis of proteins in plants is disrupted, and then the synthesis of DNA and cell division of plants are destroyed, causing the plants to stop growing and even wither. On the other hand, this agent has a selective effect on leguminous crops. It can be rapidly decomposed into inactive compounds in leguminous plants, showing the tolerance of leguminous plants to it. It has herbicidal activity against annual broad-leaved weeds such as Chenopodium album, Polygonum hydropiper, Mollugo stricta, Polygonum nepalense, Rorippa palustris, Amaranthus viridis, Spergula arvensis, Solanum nigrum, and Capsella bursa-pastoris at the initial stage to the two-leaf stage in leguminous crop fields through foliar spraying and soil treatment.

[0003] Imazamox is insoluble in water, which is inconvenient during use. After reacting to synthesize the imazamox soluble salt, it is easily soluble in water, can significantly improve the drug efficacy, and is convenient to use. CN113620928A discloses a synthesis method of imazamox sodium salt. During the compound synthesis process, the imazamox sodium salt solution is obtained by water layering. Currently, there is no literature disclosing how to prepare soluble salts with imazamox. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing imazamox soluble salt using an organic solvent as a reaction medium and an extraction agent, and the raw materials can be recycled.

[0005] The present invention adopts the following technical solutions:

[0006] A cyclic preparation method of imazamox soluble salt, comprising the following steps:

[0007] (1) Add a reaction medium to a reaction kettle, heat up, add the imazamox technical material, and start stirring;

[0008] (2) Slowly add a reactable base, after reacting for 1 - 3 h, turn off the heating, add an extraction solvent, and continue stirring for 0.5 - 2 h;

[0009] (3) Centrifuge and filter to separate the filtrate and the solid. After drying the solid, the imazamox soluble salt can be obtained.

[0010] In some embodiments, the preparation method further includes step (4): adding an ionic liquid to the separated filtrate, heating up for extractive distillation to separate out the reaction medium and the extraction solvent, and adding the reaction medium and the extraction solvent into a reaction kettle for recycling.

[0011] In some embodiments, the reaction medium is methanol, ethanol, isopropanol or butanol, preferably ethanol.

[0012] In some embodiments, the reactive base is ammonium bicarbonate, isopropylamine, dimethylamine, ethanolamine or triethanolamine.

[0013] In some embodiments, the extraction solvent is a mixture of dimethyl carbonate and butyl acetate in a proportion, and the mixing mass ratio is 3:1 to 5:1, preferably 4:1.

[0014] In some embodiments, the reaction temperature is 50 - 60 °C.

[0015] In some embodiments, the addition amount of imazamox is 200 - 300 kg, the addition amount of soluble base is 40 - 120 kg, the addition amount of reaction solvent medium is 150 - 250 kg, and the addition amount of extraction solvent is 300 - 400 kg. In some embodiments, the molar ratio of imazamox to soluble base is 1:1.

[0016] In some embodiments, the solid drying conditions are: drying at 60 - 70 °C for 2 h.

[0017] In some embodiments, the ionic liquid is an imidazole-based ionic liquid, 1-ethyl-2,3-dimethylimidazolium acetate, 1-ethyl-2,3-dimethylimidazolium ethyl sulfate, 1-ethyl-2,3-dimethylimidazolium hexafluorophosphate for separating ethanol and dimethyl carbonate; preferably 1-ethyl-2,3-dimethylimidazolium hexafluorophosphate.

[0018] In some embodiments, the addition amount of ionic liquid is 50 - 100 kg.

[0019] In some embodiments, the specific steps of step (4) are: adding the filtered solution into a rectifying column, adding an ionic liquid, controlling the top temperature of the column to be 60 - 80 °C, and the bottom temperature of the column to be 150 - 160 °C for extractive distillation separation.

[0020] Compared with the prior art, the beneficial effects of the present invention at least include:

[0021] The present invention provides a preparation method for the cyclic imazamox soluble salt. By optimizing the reaction medium, base and extraction solvent, the recovery rate of imazamox soluble salt can reach up to 97.3%; and by using ionic liquid for extractive distillation to separate the reaction medium, the purity can reach up to 97.5% at most, realizing recycling. Detailed Embodiments

[0022] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific examples described in the following embodiments of the present invention are only illustrative descriptions of the specific embodiments of the present invention, intended to explain the present invention, and do not constitute a limitation to the present invention.

[0023] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include those close to these ranges.

[0024] Example 1: Influence of Reaction Medium on the Preparation of Imazamox Soluble Salt

[0025] The reaction steps of Preparation Examples 1-4 are the same, only the reaction solvent media are different.

[0026] Taking Preparation Example 1 as an example for the reaction steps: Add the reaction solvent medium methanol into the reaction kettle, heat it to 55 °C, start stirring, add the original imazamox drug (with a content of 96.5%) into the reaction kettle, start stirring, and then slowly add ammonium bicarbonate. Stop heating 2 hours after the feeding is completed until there is no obvious solid component in the reaction solution, and then stop stirring. While cooling, add a mixed solvent of dimethyl carbonate and butyl acetate. When the temperature drops to 40 °C, the ammonium salt of imazamox starts to precipitate. Let it stand for 2 hours until no more imazamox precipitates, and then filter. The filtered solid is dried at 60-70 °C for 2 hours. The filtrate is added with an ionic liquid (1-ethyl-2,3-dimethylimidazolium hexafluorophosphate), and the temperature is raised for extraction rectification. Control the top temperature at 60 °C and the bottom temperature at 150 °C for extraction rectification separation. Methanol is separated at the top of the column, and the separated methanol can continue to be used as the reaction medium for imazamox. The mixture of dimethyl carbonate and butyl acetate separated at the bottom of the column can continue to be used as the extraction solvent for the extraction and separation of imazamox soluble salt. After the preparation of ammonium salt of imazamox is carried out again, the recovery rate is calculated.

[0027] The raw material compositions and yields of specific Preparation Examples 1-4 are shown in the following table:

[0028]

[0029] In Comparative Examples 1-2, other solvents were used as the reaction medium, and the remaining parameters remained unchanged:

[0030] Comparative Example 1: Add water into a reaction kettle, heat it to 55 °C, start stirring, add the original imazethapyr drug (with a content of 96.5%) into the reaction kettle, and then slowly add ammonium bicarbonate. Stop heating 2 h after the feeding is completed until there is no obvious solid component in the reaction solution. While cooling, add a mixture of dimethyl carbonate and butyl acetate. Finally, no solid salt is precipitated, and the imazethapyr ammonium salt cannot be separated out by this method.

[0031] Comparative Example 2: Add ethyl acetate into a reaction kettle, heat it to 55 °C, start stirring, add the original imazethapyr drug (with a content of 96.5%) into the reaction kettle, and then slowly add ammonium bicarbonate. Stop heating after 2 h. Most of the unreacted imazethapyr solids still exist in the reaction solution. Filter the reaction solution to filter out the unreacted imazethapyr. While cooling the filtrate, add a mixture of dimethyl carbonate and butyl acetate, and let it stand for 2 h until the imazethapyr ammonium salt no longer precipitates. Filter, wash the filtered solid with distilled water and then dry and weigh it. Test the content of the unreacted imazethapyr and calculate the recovery rate.

[0032] The specific raw material compositions and yields of Comparative Examples 1 - 2 are shown in the following table:

[0033]

[0034] Example 2: Influence of extraction solvent on the preparation of soluble salts of imazethapyr

[0035] The reaction steps of Preparation Examples 5 - 7 are the same, only the extraction solvents are different.

[0036] The reaction steps are as follows: Add ethanol, the reaction solvent medium, into a reaction kettle, heat it to 55 °C, start stirring, add the original imazethapyr drug (with a content of 96.5%) into the reaction kettle, start stirring, and then slowly add ammonium bicarbonate. Stop heating 2 h after the feeding is completed until there is no obvious solid raw material in the reaction solution, and then stop stirring. While cooling, add different mixed solvents for extraction. When the temperature drops to 40 °C, the imazethapyr ammonium salt starts to precipitate. Let it stand for 2 h until no more imazethapyr precipitates, and then filter. The filtered solid is dried at 60 - 70 °C for 2 h. The filtrate is added with an ionic liquid (1-ethyl-2,3-dimethylimidazolium hexafluorophosphate), and the temperature is raised for extractive distillation. Control the top temperature of the column at 60 °C and the bottom temperature of the column at 150 °C for extractive distillation separation. Methanol is separated out at the top of the column, and the separated methanol can continue to be used as the reaction medium for imazethapyr. The mixture of dimethyl carbonate and butyl acetate separated out at the bottom of the column can continue to be used as the extraction solvent to extract and separate the soluble salts of imazethapyr. After preparing the imazethapyr ammonium salt again, calculate the recovery rate.

[0037] The specific raw material compositions and yields of Preparation Examples 5 - 7 are shown in the following table:

[0039]

[0040] Comparative Examples 3-6 used other extraction solvents as the reaction medium, with the remaining parameters unchanged:

[0041] Add the reaction solvent medium ethanol into the reaction kettle, heat it to 55 °C, start stirring, add the original imazethapyr drug (content 96.5%) into the reaction kettle, start stirring, then slowly add ammonium bicarbonate. Stop heating 2 hours after the feeding is completed, and stop stirring until there is no obvious solid raw material in the reaction solution. Add different mixed solvents for extraction while cooling. After standing for 2 hours until imazethapyr no longer precipitates, then filter. The filtered solid is dried at 60-70 °C for 2 hours, filtered, and the filtered solid is dried at 60-70 °C for 2 hours, and the yield is calculated by weighing.

[0042] The specific raw material compositions and yields of Comparative Examples 3-6 are shown in the following table:

[0043]

[0044] Example 3: Influence of ionic liquid on the recovery of reaction medium and extraction solvent

[0045] The reaction steps of Preparation Examples 8-13 are the same, only the ionic liquids are different.

[0046] The reaction steps are as follows: Add the reaction solvent medium ethanol into the reaction kettle, heat it to 55 °C, start stirring, add the original imazethapyr drug (content 96.5%) into the reaction kettle, start stirring, then slowly add ammonium bicarbonate. Stop heating 2 hours after the feeding is completed, and stop stirring until there is no obvious solid raw material in the reaction solution. Add a mixed solvent of dimethyl carbonate and butyl acetate for extraction while cooling. When the temperature drops to 40 °C, the ammonium salt of imazethapyr begins to precipitate. After standing for 2 hours, filter until imazethapyr no longer precipitates. The filtered solid is dried at 60-70 °C for 2 hours, and different types of ionic liquids are added to the filtrate, and the temperature is raised for extractive distillation. Control the top temperature at 60 °C and the bottom temperature at 150 °C for extractive distillation separation. Ethanol is separated at the top of the column, and a mixture of dimethyl carbonate and butyl acetate is separated at the bottom of the column. The ethanol content in the solutions separated at the top and bottom of the column is measured using gas chromatography.

[0047] The specific raw material compositions and yields of Preparation Examples 8-13 are shown in the following table:

[0048]

[0049] Comparative Examples 7-10 used other types of ionic liquids or reduced the amount of ionic liquid for comparative testing.

[0050] The reaction steps are as follows: Add the reaction solvent medium ethanol into the reaction kettle, heat it to 55 °C, start stirring, add the original imazethapyr drug (with a content of 96.5%) into the reaction kettle, start stirring, and then slowly add ammonium bicarbonate. Stop heating 2 hours after the feeding is completed until there is no obvious solid raw material in the reaction solution, and then stop stirring. While cooling, add a mixed solvent of dimethyl carbonate and butyl acetate for extraction. When the temperature drops to 40 °C, the ammonium salt of imazethapyr starts to precipitate. Let it stand for 2 hours, and then filter until no more imazethapyr precipitates. The filtered solid is dried at 60 - 70 °C for 2 hours. The filtrate is added with different types of ionic liquids, and the temperature is raised for extractive distillation. Control the top temperature of the column at 60 °C and the bottom temperature of the column at 150 °C for extractive distillation separation. Ethanol is separated at the top of the column, and a mixture of dimethyl carbonate and butyl acetate is separated at the bottom of the column. The ethanol content in the solutions separated at the top and bottom of the column is measured using gas chromatography.

[0051]

[0052] Example 4: Influence of the reaction base on the preparation of soluble salts of imazethapyr

[0053] The reaction steps of Preparation Examples 14 - 17 are the same, only the reaction bases are different.

[0054] The reaction steps are as follows: Add the reaction solvent medium ethanol into the reaction kettle, heat it to 55 °C, start stirring, add the original imazethapyr drug (with a content of 96.5%) into the reaction kettle, start stirring, and then slowly add different types of bases. Stop heating 2 hours after the feeding is completed until there is no obvious solid raw material in the reaction solution, and then stop stirring. While cooling, add different mixed solvents for extraction. When the temperature drops to 40 °C, the ammonium salt of imazethapyr starts to precipitate. Let it stand for 2 hours, and then filter until no more imazethapyr precipitates. The filtered solid is dried at 60 - 70 °C for 2 hours. The filtrate is added with an ionic liquid (1 - ethyl - 2,3 - dimethylimidazolium hexafluorophosphate), and the temperature is raised for extractive distillation. Control the top temperature of the column at 60 °C and the bottom temperature of the column at 150 °C for extractive distillation separation. Methanol is separated at the top of the column, and the separated methanol can continue to be used as the reaction medium for imazethapyr. The mixture of dimethyl carbonate and butyl acetate separated at the bottom of the column can continue to be used as the extraction solvent for extractive separation of soluble salts of imazethapyr. After preparing the ammonium salt of imazethapyr again, the recovery rate is calculated.

[0055] The raw material compositions and yields of specific Preparation Examples 14 - 17 are shown in the following table:

[0056]

[0057] The proposed solution of the present invention can achieve good yields for different types of soluble salts of imazethapyr.

[0058] Example 5: The optimized experimental scheme

[0059] Put 200 kg of ethanol into the reactor, heat it up to 55 °C, add 250 kg of imazethapyr and stir, then slowly add 65 kg of ammonium bicarbonate. After 2 h of reaction, while cooling, add a mixed solution of 400 kg of dimethyl carbonate:butyl acetate = 4:1, let it stand for 2 h until the solid completely precipitates, centrifuge and filter, and collect the filtered solid and dry it at 60 - 70 °C for 2 h to obtain the soluble salt of imazethapyr.

[0060] Collect the filtered solution and add it to the rectification column, add 85 kg of 1-ethyl-2,3-dimethylimidazolium hexafluorophosphate, the top temperature of the column is 60 - 80 °C, and the bottom temperature of the column is 150 - 160 °C. Carry out extractive rectification separation.

[0061] It is measured that the recovery rate of imazethapyr can reach 97.3%, the purity of the ethanol separated by rectifying ethanol can reach 97.5%, and the separated ethanol and the dimethyl carbonate - butyl acetate mixture can both be recycled.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and do not constitute a limitation to the content of the present invention. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining each technical feature in any other suitable way. These

[0063] simple modifications and combinations should also be regarded as the content disclosed by the present invention and all fall within the protection scope of the present invention.

Claims

1. A circulating method for preparing a soluble salt of imazamox, characterized in that: The steps include: (1) adding a reaction medium into a reaction kettle, raising the temperature, adding imazamox technical, and starting stirring; (2) slowly adding a reactive base, turning off the heating after reacting for 1 to 3 hours, adding the extraction solvent and continuing stirring for 0.5 to 2 hours; (3) centrifugation to separate the filtrate and the solid, and drying the solid to obtain the soluble salt of imazamox.

2. The preparation method according to claim 1, characterized in that The preparation method also includes step (4): adding ionic liquid to the separated filtrate, heating and extracting and distilling to separate the reaction medium and the extraction solvent, and adding the reaction medium and the extraction solvent to the reactor for recycling.

3. The preparation method according to claim 1, characterized in that: The reaction medium is methanol, ethanol, isopropanol or butanol, preferably ethanol; the reactive base is ammonium bicarbonate, isopropylamine, dimethylamine, ethanolamine or triethanolamine.

4. The preparation method according to claim 1, characterized in that: The extraction solvent is a mixture of dimethyl carbonate and butyl acetate in a ratio of 3:1 to 5:1, preferably 4:

1.

5. The preparation method according to claim 1, characterized in that: The reaction temperature is 50-60°C.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The amount of imazamox added is 200-300 kg, the amount of soluble base added is 40-120 kg, the amount of reaction solvent medium added is 150-250 kg, and the amount of extraction solvent added is 300-400 kg; preferably, the molar ratio of imazamox to the soluble base is 1:

1.

7. The preparation method according to claim 1, characterized in that: Solid drying conditions: drying at 60-70°C for 2h.

8. The preparation method according to claim 2, characterized in that: The ionic liquid is an imidazole ionic liquid, and 1-ethyl-2,3-dimethylimidazolium acetate, 1-ethyl-2,3-dimethylimidazolium ethyl sulfate, and 1-ethyl-2,3-dimethylimidazolium hexafluorophosphate are used to separate ethanol and dimethyl carbonate; preferably, 1-ethyl-2,3-dimethylimidazolium hexafluorophosphate is used.

9. The preparation method according to claim 2, characterized in that: The amount of ionic liquid added is 50-100 kg.

10. The preparation method according to claim 2, characterized in that: The specific steps of step (4) are: adding the filtered solution into a distillation tower, adding the ionic liquid, controlling the tower top temperature to 60-80°C, the tower bottom temperature to 150-160°C, and performing extractive distillation separation.

Images