Homogeneous zinc complexing process of mancozeb
By carrying out a homogeneous complexation reaction of mancozeb in an aprotic polar solvent, the stability and phytotoxicity problems of mancozeb in the prior art have been solved, and a fully complexed mancozeb with uniform particle size and high stability has been prepared, realizing safe, high-quality and efficient pesticide production.
Patent Information
- Application Number
- CN202610081203.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-21
- Publication Date
- 2026-05-12
AI Technical Summary
In existing technologies, most of the complexation processes for mancozeb are in a non-fully complexed state, resulting in poor product stability, low content, phytotoxicity, and potential harm to crops and livestock, as well as high process costs.
Manganese oxide and zinc salt are subjected to a homogeneous complexation reaction in an aprotic polar solvent or ionic liquid to form a locally homogeneous state, ensuring that the manganese oxide and zinc salt molecules collide and achieve complete complexation.
The fully complexed mancozeb with uniform particle size and high stability was prepared, which solved the problem of phytotoxicity, reduced production costs, and achieved safe, high-quality and efficient pesticide preparation.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of pesticide chemical technology, specifically relating to a homogeneous zinc complexation process for mancozeb. Background Technology
[0002] Mancozeb is an excellent protective fungicide, characterized by high efficiency, low toxicity, broad spectrum, and slow resistance development. It can control various blight diseases of fruit trees and vegetables, such as downy mildew, powdery mildew, and anthracnose, and is particularly effective against citrus black spot. The chemical name of mancozeb is ethylene dithiocarbamate-manganese zinc complex, a surface complex formed by zinc ions and the surface of mancozeb particles. Due to technological limitations, most current processes only yield partially complexed products due to the localized chemical reaction between zinc ions and mancozeb particles. The partially complexed mancozeb has low content and poor stability, and during use, the uncomplexed mancozeb rapidly releases excessive manganese ions, causing significant phytotoxicity to crops and indirect harm to humans and livestock.
[0003] Therefore, producing fully complexed mancozeb is extremely important. Currently, the main zinc complexation processes for mancozeb include grinding and azeotropic dehydration. Grinding reduces the mancozeb particle size (5-15 μm) through physical grinding, increasing the reaction contact area, promoting the complexation reaction, and improving the degree of complexation between mancozeb and zinc ions. However, grinding is time-consuming, causes severe equipment wear, and consumes a large amount of energy. Azeotropic dehydration involves azeotropic dehydration in the presence of an organic solvent that can azeotropically react with water, simultaneously performing mancozeb complexation. This is a heterogeneous zinc complexation process, and the resulting mancozeb is not fully complexed, thus still exhibiting phytotoxicity and poor stability. Therefore, researching a high-quality, stable, and low-cost production process for fully complexed mancozeb is of great significance. Summary of the Invention
[0004] In view of the content mentioned in the background art, the present invention aims to provide a homogeneous zinc complexation process for mancozeb, for producing fully complexed mancozeb, in order to solve the problems of low mancozeb content, high process cost, poor stability, phytotoxicity to crops and indirect harm to humans and animals caused by the existing technology, and to achieve the production objectives of safety, high quality, high efficiency, economy and environmental friendliness.
[0005] To achieve the above objectives, the present invention specifically adopts the following technical solution: This invention provides a homogeneous zinc complexation process for mancozeb, comprising the following steps: Step 1: Add manganese oxide and solvent to the reaction vessel, heat to 70-120℃, and continue to add zinc salt and stir for 50-150 min; The solvent is an aprotic polar solvent or an ionic liquid; Step 2: After the reaction is complete, filter the solid and dry it to obtain fully complexed mancozeb.
[0006] As a preferred embodiment, the preparation method of manganese in step one is as follows: add a dispersant to an aqueous solution of manganese ammonium and stir to dissolve, heat to 40-60℃ and add manganese sulfate aqueous solution dropwise, with the addition time controlled at 40-60 min; after the addition is completed, keep warm at 50-60℃ for 1-2 h, and filter to obtain the product.
[0007] In a preferred embodiment, the dispersant is calcium lignosulfonate, sodium calcium lignosulfonate, or sodium dibutylnaphthalenesulfonate.
[0008] In a preferred embodiment, the manganese sulfate aqueous solution is prepared by mixing manganese sulfate monohydrate and water at a mass ratio of 1.38:3; the amount of manganese sulfate aqueous solution added is based on a molar ratio of ammonium thiocyanate to manganese sulfate of 1:(1-1.1).
[0009] As a preferred embodiment, the preparation method of the mancozeb aqueous solution is as follows: ethylenediamine is added to ammonia water, and then carbon disulfide is slowly added dropwise; after the addition is completed, the reaction is kept at a constant temperature, and after the system becomes a clear orange-yellow solution, the carbon disulfide is separated by standing and separation to obtain the mancozeb aqueous solution.
[0010] In a preferred embodiment, the zinc salt in step one is at least one of zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, and their hydrates.
[0011] In a preferred embodiment, the solvent in step one is at least one of pyridine, acetonitrile, sulfolane, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, isosorbide dimethyl ether, hexamethylphosphoric triamine, N-methylpyrrolidone, quaternary ammonium salt ionic liquid, and imidazole ionic liquid.
[0012] Because manganese sulfide is heterogeneously distributed in water, while zinc salts are soluble and homogeneously distributed, thorough stirring is required during preparation to ensure the reaction of the raw materials. This can easily lead to variations in particle size and incomplete bonding of the prepared manganese sulfide zinc. However, in the system of this invention, both manganese sulfide and zinc salts have a certain solubility in the selected aprotic polar solvent or ionic liquid, allowing them to form a locally homogeneous phase. In this locally homogeneous state, manganese sulfide and zinc salts collide at the molecular level and undergo a complete complexation reaction, ultimately yielding fully complexed manganese sulfide zinc with uniform particle size.
[0013] In a preferred embodiment, the molar ratio of manganese thiocyanate to zinc salt in step one is 1:1.
[0014] In a preferred embodiment, the mass ratio of manganese thiocyanate to solvent in step one is 1:(1-12).
[0015] As a preferred embodiment, the solid drying conditions in step two are vacuum drying at 80°C.
[0016] The present invention is a locally homogeneous manganese-zinc complexation process. It utilizes the fact that manganese and zinc salt have certain solubility in polar aprotic solvents to form a locally homogeneous phase in the reaction system, thereby carrying out a homogeneous zinc complexation reaction. Manganese and zinc salt collide in molecular form and undergo a zinc complexation reaction, which can obtain a fully complexed manganese-zinc with a manganese-zinc ratio of 1:1, thus solving the problems of phytotoxicity and poor stability.
[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. By optimizing the selection of solvents used, this invention prepares fully complexed mancozeb with high content, low cost, and good stability; at the same time, its particle size is fine (<300 nm), and it can be used in the production of various dosage forms without grinding.
[0018] 2. The present invention, mancozeb, is safe for crops, environmentally friendly, and harmless to humans and animals, achieving the goal of safe, high-quality, efficient, economical, and environmentally friendly production. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0021] Preparation of ammonium thiocyanate aqueous solution: Add 66.5 g of 20% ammonia water to 50 mL of water and stir. Cool down to below 20℃ and add 46.7 g of ethylenediamine to maintain 20℃. Add 62.1 g of carbon disulfide dropwise to the mixed solution, controlling the temperature of the vessel at 40℃ for 3 hours. After the addition is complete, maintain 40℃ and keep warm for 3 hours until the ethylenediamine reaction is complete and the system becomes a clear orange-yellow solution. Cool down to 30℃, let stand and separate the liquids to obtain the ammonium thiocyanate aqueous solution.
[0022] Preparation of manganese sulfate aqueous solution: Add 138 g of manganese sulfate monohydrate to 300 g of water, stir for 30 min, filter the material to obtain manganese sulfate aqueous solution.
[0023] Example 1 A homogeneous zinc complexation process for mancozeb includes the following steps: 1. Add the prepared ammonium thiocyanate aqueous solution to 100 g of water (controlling the final mixed solution to contain 0.770 mol of ammonium thiocyanate), stir continuously and add 1.25 g of calcium lignosulfonate. After the solution is dissolved, raise the temperature to 45°C and add the prepared manganese sulfate aqueous solution dropwise (controlling the amount of manganese sulfate added to be 0.808 mol). Control the dropwise addition time within 60 min. After the dropwise addition is completed, raise the temperature to 50°C and keep it at that temperature for 1.5 h. Filter to obtain filter cake (242 g).
[0024] 2. Add the filter cake to 1800 g of dimethyl sulfoxide (DMSO), heat to 85°C, and continue to add 106 g of zinc chloride (purity 99.0%, 0.770 mol), stir for 60 min, filter, and vacuum dry the solid at 80°C to obtain 247.2 g of light yellow mancozeb powder.
[0025]
[0026] The test results showed that the content was 99.7% and the yield was 96.8%. The particle size of the mancozeb powder measured by the laser particle size analyzer was <300 nm, and the D50 was 221 nm.
[0027] Example 2 A homogeneous zinc complexation process for mancozeb includes the following steps: 1. Add the prepared ammonium thiocyanate aqueous solution to 80 g of water (controlling the final mixed solution to contain 0.767 mol of ammonium thiocyanate), stir continuously and add 1.5 g of sodium dibutylnaphthalene sulfonate. After dissolving, raise the temperature to 60°C and add the prepared manganese sulfate aqueous solution dropwise (controlling the mass of manganese sulfate added to be 0.778 mol). Control the dropwise addition time to within 60 min. After the dropwise addition is completed, raise the temperature to 50°C and keep it warm for 2 h. Filter to obtain filter cake (246 g).
[0028] 2. Add the filter cake to 2000 g of pyridine, heat to 100℃, and continue to add 223.7 g of zinc sulfate heptahydrate (purity 98.6%, 0.767 mol), stir for 90 min, filter, and vacuum dry the solid at 80℃ to obtain 243.8 g of light yellow mancozeb powder.
[0029]
[0030] The test results showed that the content was 99.5% and the yield was 95.6%. The particle size of the mancozeb powder measured by the laser particle size analyzer was <300 nm, and the D50 was 249 nm.
[0031] Example 3 A homogeneous zinc complexation process for mancozeb includes the following steps: 1. Add the prepared ammonium thiocyanate aqueous solution to 150 g of water (controlling the final mixed solution to contain 0.772 mol of ammonium thiocyanate), stir continuously and add 1.5 g of sodium dibutylnaphthalene sulfonate. After dissolving, raise the temperature to 50°C and add the prepared manganese sulfate aqueous solution dropwise (controlling the amount of manganese sulfate added to be 0.832 mol). Control the dropwise addition time within 60 min. After the dropwise addition is completed, raise the temperature to 60°C and keep it at that temperature for 1 h. Filter to obtain filter cake (261 g).
[0032] 2. Add the filter cake to 1400 g of quaternary ammonium salt ionic liquid, heat to 80℃, and continue to add 139.6 g of zinc sulfate monohydrate (purity 99.3%, 0.772 mol), stir for 120 min, filter, and vacuum dry the solid at 80℃ to obtain 249.7 g of light yellow mancozeb powder.
[0033]
[0034] The test results showed that the content was 99.3% and the yield was 97.1%. The particle size of the mancozeb powder measured by the laser particle size analyzer was <300 nm, and the D50 was 261 nm.
[0035] The preparation method of the quaternary ammonium salt ionic liquid used in this embodiment is as follows: Using tetrabutylammonium bromide (TBAB) and caffeine lactam (CPL) as raw materials: TBAB and CPL were mixed in a molar ratio of 1:2 and transferred to a flask. The flask was placed in a heated magnetic stirrer at a constant temperature of 65°C and a stirring speed of 30 rpm until a pale yellow, transparent, viscous liquid was obtained (reaction time approximately 90 min). After the reaction was complete, the liquid was vacuum dried at 80°C, cooled, and stored at room temperature. Basic parameters of the obtained ionic liquid: Appearance: colorless to pale yellow, transparent, viscous liquid; Density: approximately 1.10 g / cm³ 3 Thermal decomposition initiation temperature: approximately 283℃; viscosity is very high below 60℃, and decreases significantly above 60℃; near neutral to weakly alkaline, pH approximately 8.
[0036] Example 4 A homogeneous zinc complexation process for mancozeb includes the following steps: 1. Add the prepared ammonium thiocyanate aqueous solution to 100 g of water (controlling the final mixed solution to contain 0.770 mol of ammonium thiocyanate), stir continuously and add 1 g of sodium lignosulfonate. After the solution is dissolved, raise the temperature to 45°C and add the prepared manganese sulfate aqueous solution dropwise (controlling the amount of manganese sulfate added to be 0.808 mol). Control the dropwise addition time to within 60 min. After the dropwise addition is completed, raise the temperature to 60°C and keep it at that temperature for 1.5 h. Filter to obtain filter cake (239 g).
[0037] 2. Add the filter cake to 1300 g of dimethylformamide (DMF), heat to 90°C, and continue to add 106 g of zinc chloride (purity 99.0%, 0.770 mol). Stir for 60 min, filter, and vacuum dry the solid at 80°C to obtain 244.4 g of light yellow mancozeb powder.
[0038]
[0039] The test results showed that the content was 99.9% and the yield was 95.9%. The particle size of the mancozeb powder measured by the laser particle size analyzer was <300 nm, and the D50 was 252 nm.
[0040] Comparative Example 1 Referring to the step parameters of Embodiment 1 of the present invention, the only difference is that the solvent dimethyl sulfoxide in step 2 is replaced with an equal mass of water.
[0041] 274.5 g of pale yellow powder was obtained; the content was calculated to be 85.8% and the yield was 92.5%; the particle size of mancozeb powder measured by laser particle size analyzer was <400 nm and the D50 was 296 nm.
[0042] Comparative Example 2 Referring to the steps and parameters of Embodiment 1 of the present invention, the only difference is that the solvent dimethyl sulfoxide in step 2 is replaced with an equal mass of toluene.
[0043] 280.4 g of yellow powder was obtained; the content was calculated to be 83.0% and the yield was 91.4%; the particle size of mancozeb powder measured by laser particle size analyzer was <500 nm and the D50 was 329 nm.
[0044] Comparative Example 3 Referring to the steps and parameters of Embodiment 1 of the present invention, the only difference is that the solvent dimethyl sulfoxide in step 2 is replaced with an equal mass of trichloroethane.
[0045] 276.2 g of yellow powder was obtained; the content was calculated to be 82.5% and the yield was 89.5%; the particle size of mancozeb powder measured by laser particle size analyzer was <500 nm and the D50 was 318 nm.
[0046] Verification of the fully complexed state: First, perform a dithizone test paper experiment. Weigh 0.5 g of the sample and add 2-3 mL of distilled water, stirring thoroughly to disperse the sample. Use a glass capillary tube to spot the prepared sample onto filter paper, for a total of 2 samples and 8 spots, and allow it to air dry. Use a glass capillary tube to draw acidic dithizone solution and drop it onto one sample spot; the central pink spot appears yellow, and the outer ring appears pink. Use a glass capillary tube to draw neutral dithizone solution and drop it onto one sample spot; the central spot immediately turns pink. According to the description in "Difference between Complexed and Non-Complexed Forms of Mancozeb," this is mancozeb in its complexed state.
[0047] Next, titration methods were used to detect the presence of free manganese, zinc, and mandelic acid ions in the sample: EDTA complexometric titration was employed, adjusting the system pH to 5-6, using xylenol orange as an indicator, to titrate the uncoordinated free manganese and zinc ions in the sample. Copper salt titration was then used under neutral conditions to titrate the free dithiocarbamate ions with Cu. 2+ A stable chelate is formed. Titration with copper reagent as an indicator shows that no endpoint color change indicates the absence of free acid radicals.
[0048] The samples from Examples 1-4 and Comparative Examples 1-3 were tested respectively, and it was found that no free components were detected. All mancozeb were tightly bound and did not separate in the solvent, indicating that mancozeb was in a fully complexed state.
[0049] The experimental results above show that using a polar aprotic solvent has a significant positive impact on the reaction, improving product quality, yield, and stability. The experimental results are very stable and can achieve complete complexation.
[0050] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A homogeneous zinc complexation process for mancozeb, characterized in that, Includes the following steps: Step 1: Add manganese oxide and solvent to the reaction vessel, heat to 70-120℃, and continue to add zinc salt and stir for 50-150 min; The solvent is an aprotic polar solvent or an ionic liquid; Step 2: After the reaction is complete, filter the solid and dry it to obtain fully complexed mancozeb.
2. The homogeneous zinc complexation process for mancozeb according to claim 1, characterized in that, The preparation method of manganese in step one is as follows: add a dispersant to an aqueous solution of manganese ammonium and stir to dissolve. Heat the solution to 40-60℃ and add manganese sulfate solution dropwise. The dropwise addition time is controlled to be 40-60 min. After the dropwise addition is completed, keep the solution at 50-60℃ for 1-2 h and filter to obtain the product.
3. The homogeneous zinc complexation process for mancozeb according to claim 2, characterized in that, The dispersant is calcium lignosulfonate, sodium calcium lignosulfonate, or sodium dibutylnaphthalenesulfonate.
4. The homogeneous zinc complexation process for mancozeb according to claim 2, characterized in that, The manganese sulfate aqueous solution is prepared by mixing manganese sulfate monohydrate and water at a mass ratio of 1.38:3; the amount of manganese sulfate aqueous solution added is based on a molar ratio of ammonium thiocyanate to manganese sulfate of 1:(1-1.1).
5. The homogeneous zinc complexation process for mancozeb according to claim 2, characterized in that, The method for preparing the ammonium disulfide aqueous solution is as follows: ethylenediamine is added to ammonia water, and then carbon disulfide is slowly added dropwise; after the addition is completed, the reaction is kept at a constant temperature, and after the system becomes a clear orange-yellow solution, the carbon disulfide is separated by standing and separation to obtain the ammonium disulfide aqueous solution.
6. The homogeneous zinc complexation process for mancozeb according to claim 1, characterized in that, The zinc salt mentioned in step one is at least one of zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, and their hydrates.
7. The homogeneous zinc complexation process for mancozeb according to claim 1, characterized in that, The solvent in step one is at least one of pyridine, acetonitrile, sulfolane, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, isosorbide dimethyl ether, hexamethylphosphoric triamine, N-methylpyrrolidone, quaternary ammonium salt ionic liquid, and imidazole ionic liquid.
8. The homogeneous zinc complexation process for mancozeb according to claim 1, characterized in that, In step one, the molar ratio of manganese oxide to zinc salt is 1:
1.
9. The homogeneous zinc complexation process for mancozeb according to claim 1, characterized in that, In step one, the mass ratio of manganese thiocyanate to solvent is 1:(1-12).
10. The homogeneous zinc complexation process for mancozeb according to claim 1, characterized in that, The solid drying conditions described in step two are vacuum drying at 80°C.