Preparation method, product and application of polypeptide plant growth promoter

Abstract

The invention relates to the technical field of agricultural synergists, in particular to a preparation method, a product and application of a polypeptide plant growth promoter, and the preparation method at least comprises the following steps: after maleic anhydride reacts with an alcohol solvent, ammonia water and a catalyst are sequentially added for reaction to obtain polysuccinimide; and hydrolyzing the polysuccinimide under an alkaline condition to obtain polyaspartic acid salt, namely the polypeptide plant growth promoter. The preparation method comprises the following steps: reacting maleic anhydride with an alcohol solvent to generate a maleic acid monoester intermediate, adding ammonia water into the intermediate to generate ammonium salt of maleic acid monoester, after the reaction is finished, heating to remove water, adding a proper amount of catalyst, and carrying out polycondensation on the mixture to generate polysuccinimide; the polysuccinimide is hydrolyzed under an alkaline condition to obtain polyaspartic acid salt, and the weight-average molecular weight of the obtained polyaspartic acid salt is gt; and the production process is environment-friendly and easy to control.

Description

Technical Field

[0001] This invention relates to the field of agricultural growth enhancer technology, specifically to a method for preparing a polypeptide plant growth promoter, its product, and its application. Background Technology

[0002] Polyaspartic acid is an amino acid polymer naturally found in the shells of snails and mollusks. It is an environmentally friendly chemical widely used in water treatment, pharmaceutical carriers, and daily chemical industries. In agricultural applications, it is often used in the form of a salt. The most crucial part of polyaspartic acid preparation is the synthesis of the intermediate polysuccinimide. Existing technologies can be broadly classified into two categories: 1. Using aspartic acid as a raw material, adding a catalyst, and polymerizing at high temperature to produce polyaspartic acid, for example, Chinese invention patent CN1195000C; 2. Reacting maleic anhydride with ammonia, urea, etc., to generate the intermediate maleamic acid ammonium salt, adding a catalyst, and polymerizing at high temperature to produce polyaspartic acid.

[0003] Method 1, aspartic acid is more expensive than maleic anhydride, and the reaction is a weight-reduction reaction, increasing the raw material cost of the process. Method 2, because maleic anhydride is a solid and the salt formation reaction is exothermic, the addition of ammonia water causes a large amount of ammonia gas to volatilize, resulting in environmental pollution and resource waste. Furthermore, the amount of ammonia water volatilized varies with each feeding, affecting product quality. Summary of the Invention

[0004] To address the problems in the prior art, the first aspect of this invention provides a method for preparing a polypeptide plant growth promoter, comprising at least the following steps: Maleic anhydride reacts with an alcohol solvent, and then ammonia and a catalyst are added sequentially to obtain polysuccinimide. The polysuccinimide is hydrolyzed under alkaline conditions to obtain polyaspartic acid salt, which is the polypeptide plant growth promoter.

[0005] This invention utilizes the preferential reaction of maleic anhydride with an alcohol solvent to generate a maleic acid monoester intermediate, avoiding the hydrolysis of maleic anhydride when water is used as the solvent, which would generate maleic acid and related byproducts. This intermediate then reacts with ammonia to form the ammonium salt of the maleic acid monoester, avoiding the large amount of ammonia volatilization that occurs when maleic anhydride reacts directly with ammonia, thus reducing environmental pollution and resource waste.

[0006] In some embodiments, the preparation method includes at least the following steps: S1. Maleic anhydride is added to an alcohol solvent and heated to react and generate maleic acid monoester intermediate. After the maleic anhydride is completely dissolved, excess alcohol solvent is evaporated, and ammonia is added dropwise to the system of S1. After the addition is complete, the water is evaporated, and the catalyst is added and stirred evenly to obtain a mixture. S2. The mixture is subjected to a polymerization reaction to obtain polysuccinimide; S3. Add the polysuccinimide to water, add an alkaline solution to adjust the pH to 8-9, and hydrolyze to obtain the polyaspartic acid salt.

[0007] In some embodiments, the alcohol solvent includes a monohydric alcohol.

[0008] In some embodiments, the monohydric alcohol includes at least one of methanol, ethanol, and isopropanol.

[0009] In this application, maleic anhydride reacts with a monohydric alcohol to generate maleic acid monoester, which has a simple and stable structure. When this intermediate reacts with ammonia, only monocarboxylic acid ammonium salt is generated, which is a linear maleic acid monoester ammonium salt, providing a uniform reaction unit for subsequent polycondensation. At the same time, the low boiling point of the monohydric alcohol allows the solvent to be evaporated later, avoiding interference from high-temperature residues.

[0010] In some embodiments, the ammonia solution is 25 wt% ammonia solution.

[0011] In some embodiments, the molar ratio of maleic anhydride to alcohol solvent is 1:(1.2-4). For example, 1:1.2, 1:1.5, 1:2, 1:4, etc., or any value within the range of 1:(1.2-4).

[0012] In some embodiments, the molar ratio of ammonia to maleic anhydride is (1.2-2):1, such as 1.2:1, 1.5:1, or 2:1.

[0013] In some implementations, S1 satisfies at least one of the following conditions: A. The temperature of the heating and stirring process is ≤65℃; B. The temperature at which the ammonia water is added is ≤30℃.

[0014] In some embodiments, the dripping rate is 14 mL / min.

[0015] Ammonia has limited solubility in water, about 30% at 20°C, and the exothermic reaction during dropwise addition causes a large amount of ammonia to evaporate. Although alcohol solvents have low solubility for ammonia, by controlling the low-temperature dropwise addition and the dropwise acceleration rate of 14 mL / min, the ammonia evaporation rate is kept lower than the reaction consumption rate, ensuring the pH stability of the reaction system, uniform salt formation products, and significantly improving the stability of product quality.

[0016] In some embodiments, the polymerization temperature in S2 is 200-250°C.

[0017] In some embodiments, the hydrolysis temperature in S3 is ≤60°C.

[0018] In some embodiments, the catalyst comprises phosphoric acid.

[0019] Optionally, the phosphoric acid is phosphoric acid with a mass concentration of 80%.

[0020] In some embodiments, the alkaline solution comprises a potassium hydroxide solution; the mass concentration of the potassium hydroxide solution is 40%.

[0021] A second aspect of the present invention provides a polyaspartic acid salt, which is prepared by the above-described preparation method.

[0022] A third aspect of this invention provides an application of polyaspartic acid salt or the above-mentioned preparation method to the preparation of water-soluble fertilizers.

[0023] Beneficial effects 1. This invention uses maleic anhydride to react with an alcohol solvent to generate a maleic acid monoester intermediate. Ammonia is added to the intermediate to generate an ammonium salt of maleic acid monoester. After the reaction is completed, the water is removed by heating, and an appropriate amount of catalyst is added. The mixture is then subjected to polycondensation to generate polysuccinimide. The polysuccinimide is hydrolyzed under alkaline conditions to obtain polyaspartic acid salt. The weight average molecular weight of the obtained polyaspartic acid salt is >6000. The production process is environmentally friendly and easy to control.

[0024] 2. This invention uses an alcohol solvent to preferentially react with maleic anhydride to generate a maleic acid monoester intermediate, thus avoiding the hydrolysis of maleic anhydride when water is used as a solvent, which would generate maleic acid and corresponding byproducts.

[0025] 3. By controlling the low-temperature dripping and the dripping rate to 14 mL / min, the ammonia volatilization rate is kept lower than the reaction consumption rate, ensuring the pH of the reaction system is stable and the raw materials for the polycondensation reaction are uniform and stable.

[0026] 4. The polyaspartic acid salt provided by this invention can be applied to water-soluble fertilizers and applied to plants by spraying and seed dressing. It can significantly improve the physiological indicators of crops, effectively improve the quality of crop products, and significantly increase crop yield. Attached Figure Description

[0027] Figure 1-7 The molecular weight and distribution diagrams of the products corresponding to Examples 1-6 and Comparative Example 1 are shown respectively. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Experimental methods not specifying specific conditions in the embodiments were performed under conventional conditions or conditions recommended by the manufacturer. Reagents not specifying manufacturers are all commercially available conventional products.

[0029] Example 1 The first aspect of this example provides a method for preparing the polypeptide plant growth promoter, potassium aspartate, including the following steps: Add 485g (5mol) of maleic anhydride and 192g (6mol) of methanol to a 1000mL four-necked flask. Stir and heat to 65℃ to react and generate maleic acid monoester intermediate. After the maleic anhydride is completely dissolved, use a distillation apparatus to evaporate the methanol under reduced pressure. Cool to 20℃ and add 408g (6mol) of 25% ammonia water dropwise at a rate of 14mL / min. Keep the temperature below 30℃ and complete the addition in 0.5h. Stir for 1h, heat to 100℃, evaporate the water, add 50g of 80wt% phosphoric acid as a catalyst, and stir for 30min.

[0030] After stirring evenly, the mixture is transferred to a kneader, heated to 250°C, and kept at that temperature for 5 hours to obtain solid polysuccinimide.

[0031] Weigh 100g of polysuccinimide solid, add 200mL of water, add 100g of 40wt% potassium hydroxide aqueous solution, adjust the pH to 9, and obtain an amber transparent liquid, which is a 35wt% polyaspartic acid potassium solution.

[0032] The second aspect of this example provides a polyaspartic acid potassium, which is prepared by the above-described preparation method.

[0033] The third aspect of this example provides an application of potassium polyaspartate or the above-mentioned preparation method to the preparation of water-soluble fertilizers.

[0034] Example 2 The first aspect of this example provides a method for preparing the polypeptide plant growth promoter, potassium aspartate, including the following steps: Add 485g (5mol) of maleic anhydride and 320g (10mol) of methanol to a 2000mL four-necked flask. Stir and heat to 65℃ to react and generate maleic acid monoester intermediate. After the maleic anhydride is completely dissolved, use a distillation apparatus to evaporate the methanol under reduced pressure. Cool to 20℃ and add 408g (6mol) of 25% ammonia water dropwise at a rate of 14mL / min. Keep the temperature below 30℃ and add the water dropwise for about 0.5h. Stir for 1h, heat to 100℃, evaporate the water, add 50g of 80wt% phosphoric acid as a catalyst, and stir for 30min.

[0035] After stirring evenly, the mixture is transferred to a kneader, heated to 250°C, and kept at that temperature for 5 hours to obtain solid polysuccinimide.

[0036] Weigh 100g of polysuccinimide solid, add 200mL of water, add 100g of 40wt% potassium hydroxide aqueous solution, adjust the pH to 9, and obtain an amber transparent liquid, which is a 35wt% polyaspartic acid potassium solution.

[0037] The second aspect of this example provides a polyaspartic acid potassium, which is prepared by the above-described preparation method.

[0038] The third aspect of this example provides an application of potassium polyaspartate or the above-mentioned preparation method to the preparation of water-soluble fertilizers.

[0039] Example 3 The first aspect of this example provides a method for preparing the polypeptide plant growth promoter, potassium aspartate, including the following steps: Add 485g (5mol) of maleic anhydride and 760g (20mol) of methanol to a 2000mL four-necked flask. Stir and heat to 65℃ to react and generate maleic acid monoester intermediate. After the maleic anhydride is completely dissolved, use a distillation apparatus to evaporate the methanol under reduced pressure. Cool to 20℃ and add 408g (6mol) of 25% ammonia water dropwise at a rate of 14mL / min. Keep the temperature below 30℃ and add the water dropwise for about 0.5h. Stir for 1h, heat to 100℃, evaporate the water, add 50g of 80wt% phosphoric acid as a catalyst, and stir for 30min.

[0040] After stirring evenly, the mixture is transferred to a kneader, heated to 250°C, and kept at that temperature for 5 hours to obtain solid polysuccinimide.

[0041] Weigh 100g of polysuccinimide solid, add 200mL of water, add 100g of 40wt% potassium hydroxide aqueous solution, adjust the pH to 9, and obtain an amber transparent liquid, which is a 35wt% polyaspartic acid potassium solution.

[0042] The second aspect of this example provides a polyaspartic acid potassium, which is prepared by the above-described preparation method.

[0043] The third aspect of this example provides an application of potassium polyaspartate or the above-mentioned preparation method to the preparation of water-soluble fertilizers.

[0044] Example 4 The first aspect of this example provides a method for preparing the polypeptide plant growth promoter, potassium aspartate, including the following steps: Add 485g (5mol) of maleic anhydride and 192g (6mol) of methanol to a 1000mL four-necked flask. Stir and heat to 65℃ to react and generate maleic acid monoester intermediate. After the maleic anhydride is completely dissolved, use a distillation apparatus to evaporate the methanol under reduced pressure. Cool to 20℃ and add 408g (6mol) of 25wt% ammonia water dropwise at a rate of 14mL / min. The addition is completed in about 0.5h. Keep the temperature <30℃ and stir for 1h. Heat to 100℃ and evaporate the water. Add 50g of 80wt% phosphoric acid as a catalyst and stir for 30min.

[0045] After stirring evenly, the mixture is transferred to a kneader, heated to 200℃, and kept at that temperature for 5 hours to obtain solid polysuccinimide.

[0046] Weigh 100g of polysuccinimide solid, add 200mL of water, add 100g of 40wt% potassium hydroxide aqueous solution, adjust the pH to 9, and obtain an amber transparent liquid, which is a 35wt% polyaspartic acid potassium solution.

[0047] The second aspect of this example provides a polyaspartic acid potassium, which is prepared by the above-described preparation method.

[0048] The third aspect of this example provides an application of potassium polyaspartate or the above-mentioned preparation method to the preparation of water-soluble fertilizers.

[0049] Example 5 The first aspect of this example provides a method for preparing polyaspartic acid salt, a polypeptide plant growth promoter, including the following steps: Add 485g (5mol) of maleic anhydride and 276g (6mol) of ethanol to a 1000mL four-necked flask. Stir and heat to 65℃ to react and generate maleic acid monoester intermediate. After the maleic anhydride is completely dissolved, use a distillation apparatus to evaporate the ethanol under reduced pressure. Cool to 20℃ and add 408g (6mol) of 25% ammonia water dropwise at a rate of 14mL / min. Keep the temperature below 30℃ and add the water dropwise for about 0.5h. Stir for 1h, heat to evaporate the water, add 50g of 80wt% phosphoric acid as a catalyst, and stir for 30min.

[0050] After stirring evenly, the mixture is transferred to a kneader, heated to 250°C, and kept at that temperature for 5 hours to obtain solid polysuccinimide.

[0051] Weigh 100g of polysuccinimide solid, add 200mL of water, add 100g of 40wt% potassium hydroxide aqueous solution, adjust the pH to 9, and obtain an amber transparent liquid, which is a 35wt% polyaspartic acid potassium solution.

[0052] The second aspect of this example provides a polyaspartic acid potassium, which is prepared by the above-described preparation method.

[0053] The third aspect of this example provides an application of potassium polyaspartate or the above-mentioned preparation method to the preparation of water-soluble fertilizers.

[0054] Example 6 The first aspect of this example provides a method for preparing polyaspartic acid salt, a polypeptide plant growth promoter, including the following steps: Add 485g (5mol) of maleic anhydride and 360g (6mol) of isopropanol to a 1000mL four-necked flask. Stir and heat to 65℃ to react and generate maleic acid monoester intermediate. After the maleic anhydride is completely dissolved, use a distillation apparatus to evaporate the isopropanol under reduced pressure. Cool to 20℃ and add 408g (6mol) of 25% ammonia water dropwise at a rate of 14mL / min. Keep the temperature below 30℃ and add the water dropwise for about 0.5h. Stir for 1h, heat to evaporate the water, add 50g of 80wt% phosphoric acid as a catalyst, and stir for 30min.

[0055] After stirring evenly, the mixture is transferred to a kneader, heated to 250°C, and kept at that temperature for 5 hours to obtain solid polysuccinimide.

[0056] Weigh 100g of polysuccinimide solid, add 200mL of water, add 100g of 40wt% potassium hydroxide aqueous solution, adjust the pH to 9, and obtain an amber transparent liquid, which is a 35wt% polyaspartic acid potassium solution.

[0057] The second aspect of this example provides a polyaspartic acid potassium, which is prepared by the above-described preparation method.

[0058] The third aspect of this example provides an application of potassium polyaspartate or the above-mentioned preparation method to the preparation of water-soluble fertilizers.

[0059] Comparative Example 1 The first aspect of this example provides a method for preparing the polypeptide plant growth promoter, potassium aspartate, including the following steps: Add 485g (5mol) of maleic anhydride to a 1000mL four-necked flask in an ice-water bath, add 200g of water, and add 510g (7.5mol) of 25% ammonia solution dropwise. Control the temperature to not exceed 40℃. After the maleic anhydride is completely dissolved, check the pH of the solution to 8 (if pH < 8, ammonia solution needs to be added to pH = 8). Stir for 1 hour, raise the temperature to 100℃, evaporate the water and excess ammonia solution, add 50g of 80wt% phosphoric acid as a catalyst, and stir for 30min.

[0060] After stirring evenly, the mixture is transferred to a kneader, heated to 250°C, and kept at that temperature for 5 hours to obtain solid polysuccinimide.

[0061] Weigh 100g of polysuccinimide solid, add 200mL of water, add 100g of 40wt% potassium hydroxide aqueous solution, adjust pH=9, and obtain an amber transparent liquid, which is a 35wt% polyaspartic acid potassium solution.

[0062] The second aspect of this example provides a polyaspartic acid potassium, which is prepared by the above-described preparation method.

[0063] The third aspect of this example provides an application of potassium polyaspartate or the above-mentioned preparation method to the preparation of water-soluble fertilizers.

[0064] Performance testing 1. The molecular weight and distribution of the products prepared in each example and comparative example were determined using gel permeation chromatography (GPC). The test environment was as follows: Instrument Model: Agilent 1260 Infinity II Mobile phase: 0.1M NaNO3 Detector: RID Columns: Waters Ultrahydrogel 1000 and Waters Ultrahydrogel 120 in tandem Temperature: 40℃ Flow rate: 0.8 mL / min Standard product: dextran.

[0065] The above test results are shown in Figure 1-7 .

[0066] As can be seen from the figure, the weight-average molecular weight of Example 1 is 8866; the weight-average molecular weight of Example 2 is 8604; the weight-average molecular weight of Example 3 is 8519; the weight-average molecular weight of Example 4 is 7076; the weight-average molecular weight of Example 5 is 8081; and the weight-average molecular weight of Example 6 is 6586. The weight-average molecular weight of all examples is >6000 and has a single-peak distribution with uniform distribution.

[0067] In Comparative Example 1, the molecular weight of the product showed two peaks with weight-average molecular weights of 5111 and 804, respectively. The area ratio of the two peaks was 81.7:18.3, indicating an uneven molecular weight distribution, and the weight-average molecular weight was <6000.

[0068] 2. Effect test: 1) Example 1: Spraying apples: The 35wt% potassium polyaspartate solution described in Example 1 was diluted 1000 times with water and sprayed on apples during the flowering, fruit setting, young fruit, and fruit enlargement stages. A water treatment was used as a blank control group. Statistical analysis of the experimental results showed that the use of polyaspartic acid nutrient solution not only greatly improved the coloring rate and fruit grade of the fruit, but also increased the yield by 16%.

[0069] 2) Example 2: Seed-treated wheat: 30 ml of the 35 wt% potassium polyaspartate solution described in Example 1 was dissolved in 60 mL of purified water and used to treat 30 catties of wheat seeds. The water treatment was used as a blank control group. Statistical analysis of the experimental results showed that the wheat seeds treated with aspartic acid had a 20% longer root system during the seedling stage compared to the blank control group, and the final yield was 18% higher than that of the blank control group.

[0070] 3) Example 3: Spraying garlic: The 35wt% potassium polyaspartate solution described in Example 1 was diluted 1000 times with water and sprayed on the leaves at 20-day intervals during the garlic growth process. The spraying was repeated 4 times. A water treatment was used as a blank control group for comparison. The garlic yield increased by 22%.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a polypeptide-based plant growth promoter, characterized in that, At least the following steps are included: Maleic anhydride reacts with an alcohol solvent, and then ammonia and a catalyst are added sequentially to obtain polysuccinimide. The polysuccinimide is hydrolyzed under alkaline conditions to obtain polyaspartic acid salt, which is the polypeptide plant growth promoter.

2. The preparation method according to claim 1, characterized in that, At least the following steps are included: S1. Maleic anhydride is added to an alcohol solvent and heated to react and generate maleic acid monoester intermediate. After the maleic anhydride is completely dissolved, excess alcohol solvent is evaporated, and ammonia is added dropwise to the system of S1. After the addition is complete, the water is evaporated, and the catalyst is added and stirred evenly to obtain a mixture. S2. The mixture is subjected to a polymerization reaction to obtain polysuccinimide; S3. Add the polysuccinimide to water, add an alkaline solution to adjust the pH to 8-9, and hydrolyze to obtain the polyaspartic acid salt.

3. The preparation method according to claim 1 or 2, characterized in that, The alcohol solvents include monohydric alcohols.

4. The preparation method according to claim 1 or 2, characterized in that, The molar ratio of maleic anhydride to alcohol solvent is 1:(1.2-4).

5. The preparation method according to claim 1 or 2, characterized in that, The molar ratio of ammonia to maleic anhydride is (1.2-2):

1.

6. The preparation method according to claim 2, characterized in that, S1 satisfies at least one of the following conditions: A. The temperature of the heating and stirring process is ≤65℃; B. The temperature at which the ammonia water is added is ≤30℃.

7. The preparation method according to claim 2, characterized in that, The polymerization temperature in S2 is 200-250℃.

8. The preparation method according to claim 2, characterized in that, The hydrolysis temperature in S3 is ≤60℃.

9. A polyaspartic acid salt, characterized in that, It is prepared according to any one of claims 1-8.

10. The application of the polyaspartic acid salt according to claim 9, or the preparation method according to any one of claims 1-8, characterized in that, It is used in the preparation of water-soluble fertilizers.

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