A plant insecticide and a method for preparing the same

Abstract

The present application relates to the technical field of insecticide, and discloses a plant insecticide and a preparation method thereof, which comprises the following components by weight: 1-2 parts of pyridine insecticide, 0.8-1 parts of carvacrol, 3-5 parts of modified starch and 3-4.5 parts of sodium alginate. The pyridine insecticide and the carvacrol are compounded, and the two play a synergistic effect, which significantly improves the toxic activity on agricultural pests, and the insecticidal efficiency is effectively improved compared with the single use of the pyridine insecticide or the carvacrol. The carvacrol in the plant insecticide is derived from plant extraction, and has the characteristics of easy degradation and low toxicity; the modified starch and the sodium alginate are both natural polymer materials, can be biodegraded, and will not cause pollution to the soil and water, which meets the development demand of green agriculture.

Description

Technical Field

[0001] This invention relates to the field of insecticide technology, specifically to a plant-based insecticide and its preparation method. Background Technology

[0002] In agricultural production, pests and diseases are key factors restricting crop yield and quality improvement, and the application of pesticides is indispensable for efficient pest and disease control. While traditional chemical pesticides can achieve good insecticidal effects in the short term, long-term, large-scale use presents several prominent problems: they not only disrupt soil microbial communities and pollute water resources, but also pose a potential threat to human health through bioaccumulation in the food chain; long-term use also exacerbates environmental pressure and agricultural production costs. Currently available plant-derived pesticides, while possessing advantages such as environmental friendliness and low residue, generally suffer from insufficient insecticidal activity, making it difficult to meet the needs of large-scale agricultural pest and disease control. Furthermore, the unreasonable selection of excipients in some pesticide formulations leads to weak adhesion to crop surfaces, and the active ingredients are easily washed away by rainwater, further reducing insecticidal efficacy. Therefore, developing an insecticide that combines high insecticidal activity, environmental friendliness, low residue, and long-lasting effectiveness has become an urgent technical problem to be solved in the agricultural field. Summary of the Invention

[0003] Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a plant-based insecticide and its preparation method, which exhibits good insecticidal effects.

[0005] Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a plant-based insecticide comprising the following weight components: 1-2 parts by weight of pyridine insecticide, 0.8-1 parts by weight of carvacrol, 3-5 parts by weight of modified starch, and 3-4.5 parts by weight of sodium alginate.

[0007] Furthermore, the preparation method of the pyridine insecticide is as follows:

[0008] S1. Add 2-aminopyridine and 2-chloro-5-(chloromethyl)pyridine to tetrahydrofuran solvent, stir and mix, continue to add sodium hydride, react at 55-60℃ for 2-4h, then add 0.1mol / L dilute hydrochloric acid to adjust the pH to neutral, wash, dry, and obtain intermediate 1;

[0009] S2. Add 6-chloro-1-hexanol and intermediate 1 to N,N-dimethylformamide solvent, stir to dissolve, react at 60-65℃ for 2-3 hours, distill under reduced pressure after reaction, wash to obtain pyridine insecticide.

[0010] Furthermore, in S1, the ratio of 2-aminopyridine, 2-chloro-5-(chloromethyl)pyridine, and sodium hydride is 2-3 mmol: 2-3 mmol: 0.1-0.2 mmol.

[0011] Furthermore, in S2, the ratio of 6-chloro-1-hexanol to intermediate 1 is 0.27-0.34 g: 2-2.6 mmol.

[0012] Further, the modified starch is prepared by dissolving starch in a reaction flask containing deionized water, then adding sodium periodate, sonicating to form a starch slurry, adding 1 mol / L hydrochloric acid to adjust the pH, heating the reaction for 2-4 hours, adding ethylene glycol after the reaction, stirring for 8-12 minutes, then adding 1 mol / L sodium hydroxide solution to adjust the pH to neutral, filtering, and washing with anhydrous ethanol to obtain the modified starch.

[0013] Furthermore, the ratio of starch, deionized water, sodium periodate, and ethylene glycol is 4-5g: 90-100mL: 6.3-6.7g: 3.6-3.9g.

[0014] Furthermore, the heating reaction is carried out for 2-4 hours at a temperature of 30-35°C.

[0015] Furthermore, the preparation method of the plant insecticide is as follows: add pyridine insecticide, modified starch, and sodium alginate into a stirrer and stir for 15-20 minutes to obtain the plant insecticide.

[0016] Beneficial technical effects

[0017] This invention combines pyridine insecticides with carvacrol, achieving a synergistic effect that significantly enhances their toxicity against agricultural pests. Compared to using either pyridine or carvacrol alone, the insecticidal efficiency is effectively improved. Carvacrol, a plant-based insecticide, is derived from plants and is inherently biodegradable and low in toxicity. Modified starch and sodium alginate are both natural polymer materials that are biodegradable and will not pollute soil or water, thus meeting the needs of green agriculture development.

[0018] After being oxidized with sodium periodate, modified starch forms more active groups in its molecular structure. These groups work synergistically with the hydroxyl groups in sodium alginate and pyridine insecticides to form a uniform and stable protective film on the crop surface. This effectively enhances the adhesion of the insecticide to the crop surface and reduces the loss of active ingredients due to rainwater erosion. At the same time, this protective film can also slow down the volatilization and photodecomposition rate of the active ingredients, thus extending the insecticide's effective period. Attached Figure Description

[0019] Figure 1 This is the reaction formula for the preparation of pyridine insecticide in Example 1. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To better understand the above technical solutions, the following will provide a detailed description of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0022] Starch: Tapioca starch.

[0023] Example 1

[0024] A plant-based insecticide comprising the following components by weight: 1 part by weight of pyridine insecticide, 0.8 parts by weight of carvacrol, 3 parts by weight of modified starch, and 3 parts by weight of sodium alginate.

[0025] The preparation method of the pyridine insecticide is as follows:

[0026] S1. Add 2 mmol of 2-aminopyridine and 2 mmol of 2-chloro-5-(chloromethyl)pyridine to 30 mL of tetrahydrofuran solvent, stir and mix, then add 0.1 mmol of sodium hydride, react at 55 °C for 2 h, then add 0.1 mol / L dilute hydrochloric acid to adjust the pH to neutral, wash, dry, and obtain intermediate 1;

[0027] S2. Add 0.27 g of 6-chloro-1-hexanol and 2 mmol of intermediate 1 to 35 mL of N,N-dimethylformamide solvent, stir to dissolve, react at 60 °C for 2 h, and then distill under reduced pressure and wash to obtain pyridine insecticide.

[0028] The modified starch is prepared as follows: 4g of starch is added to a reaction flask containing 90mL of deionized water for dissolution, and then 6.3g of sodium periodate is added. The mixture is sonicated to form a starch slurry. 1mol / L hydrochloric acid is added to adjust the pH, and the mixture is heated to 30℃ for 2h. After the reaction is completed, 3.6g of ethylene glycol is added and stirred for 8min. Then, 1mol / L sodium hydroxide solution is added to adjust the pH to neutral. The mixture is filtered and washed with anhydrous ethanol to obtain the modified starch.

[0029] The preparation method of the plant insecticide is as follows: add pyridine insecticide, modified starch, and sodium alginate into a stirrer and stir for 15 minutes to obtain the plant insecticide.

[0030] Example 2

[0031] A plant-based insecticide comprising the following components by weight: 2 parts by weight of pyridine insecticide, 1 part by weight of carvacrol, 5 parts by weight of modified starch, and 4.5 parts by weight of sodium alginate.

[0032] The preparation method of the pyridine insecticide is as follows:

[0033] S1. Add 3 mmol of 2-aminopyridine and 3 mmol of 2-chloro-5-(chloromethyl)pyridine to 45 mL of tetrahydrofuran solvent, stir and mix, then add 0.2 mmol of sodium hydride, react at 60 °C for 4 h, then add 0.1 mol / L dilute hydrochloric acid to adjust the pH to neutral, wash, dry, and obtain intermediate 1;

[0034] S2. Add 0.34 g of 6-chloro-1-hexanol and 2.6 mmol of intermediate 1 to 40 mL of N,N-dimethylformamide solvent, stir to dissolve, react at 65 °C for 3 h, and then distill under reduced pressure and wash to obtain pyridine insecticide.

[0035] The modified starch is prepared as follows: 5g of starch is added to a reaction flask containing 100mL of deionized water for dissolution, and then 6.7g of sodium periodate is added. The mixture is sonicated to form a starch slurry. 1mol / L hydrochloric acid is added to adjust the pH, and the mixture is heated to 35℃ for 4h. After the reaction is completed, 3.9g of ethylene glycol is added and stirred for 12min. Then, 1mol / L sodium hydroxide solution is added to adjust the pH to neutral. The mixture is filtered and washed with anhydrous ethanol to obtain the modified starch.

[0036] The preparation method of the plant insecticide is as follows: add pyridine insecticide, modified starch and sodium alginate into a stirrer and stir for 20 minutes to obtain the plant insecticide.

[0037] Example 3

[0038] A plant-based insecticide comprising the following components by weight: 1.5 parts by weight of pyridine insecticide, 0.9 parts by weight of carvacrol, 4 parts by weight of modified starch, and 3.6 parts by weight of sodium alginate.

[0039] The preparation method of the pyridine insecticide is as follows:

[0040] S1. Add 2.5 mmol of 2-aminopyridine and 2.6 mmol of 2-chloro-5-(chloromethyl)pyridine to 35 mL of tetrahydrofuran solvent, stir and mix, then add 0.15 mmol of sodium hydride, react at 58 °C for 3 h, then add 0.1 mol / L dilute hydrochloric acid to adjust the pH to neutral, wash, dry, and obtain intermediate 1;

[0041] S2. Add 0.31 g of 6-chloro-1-hexanol and 2.3 mmol of intermediate 1 to 38 mL of N,N-dimethylformamide solvent, stir to dissolve, react at 62 °C for 2.5 h, distill under reduced pressure after reaction, wash to obtain pyridine insecticide.

[0042] The modified starch is prepared as follows: 4.5g of starch is added to a reaction flask containing 95mL of deionized water for dissolution, and then 6.5g of sodium periodate is added. The mixture is sonicated to form a starch slurry. 1mol / L hydrochloric acid is added to adjust the pH, and the mixture is heated to 32℃ for 3h. After the reaction is completed, 3.8g of ethylene glycol is added and stirred for 10min. Then, 1mol / L sodium hydroxide solution is added to adjust the pH to neutral. The mixture is filtered and washed with anhydrous ethanol to obtain the modified starch.

[0043] The preparation method of the plant insecticide is as follows: add pyridine insecticide, modified starch and sodium alginate into a stirrer and stir for 17 minutes to obtain the plant insecticide.

[0044] Example 4

[0045] A plant-based insecticide comprising the following components by weight: 1 part by weight of pyridine insecticide, 0.8 parts by weight of carvacrol, 3 parts by weight of modified starch, and 3 parts by weight of sodium alginate.

[0046] The preparation method of the pyridine insecticide is as follows:

[0047] S1. Add 2 mmol of 2-aminopyridine and 2 mmol of 2-chloro-5-(chloromethyl)pyridine to 30 mL of tetrahydrofuran solvent, stir and mix, then add 0.1 mmol of sodium hydride, react at 55 °C for 2 h, then add 0.1 mol / L dilute hydrochloric acid to adjust the pH to neutral, wash, dry, and obtain intermediate 1;

[0048] S2. Add 0.34 g of 6-chloro-1-hexanol and 2.6 mmol of intermediate 1 to 40 mL of N,N-dimethylformamide solvent, stir to dissolve, react at 65 °C for 3 h, and then distill under reduced pressure and wash to obtain pyridine insecticide.

[0049] The modified starch is prepared as follows: 4.5g of starch is added to a reaction flask containing 95mL of deionized water for dissolution, and then 6.5g of sodium periodate is added. The mixture is sonicated to form a starch slurry. 1mol / L hydrochloric acid is added to adjust the pH, and the mixture is heated to 32℃ for 3h. After the reaction is completed, 3.8g of ethylene glycol is added and stirred for 10min. Then, 1mol / L sodium hydroxide solution is added to adjust the pH to neutral. The mixture is filtered and washed with anhydrous ethanol to obtain the modified starch.

[0050] The preparation method of the plant insecticide is as follows: add pyridine insecticide, modified starch and sodium alginate into a stirrer and stir for 17 minutes to obtain the plant insecticide.

[0051] Comparative Example 1

[0052] This comparative example differs from Example 4 in that intermediate 1 is used instead of pyridine insecticide. Details are as follows:

[0053] A plant-based insecticide comprising the following components by weight: 1 part by weight of intermediate 1, 0.8 parts by weight of carvacrol, 3 parts by weight of modified starch, and 3 parts by weight of sodium alginate.

[0054] The preparation method of the pyridine insecticide is as follows:

[0055] S1. Add 2 mmol of 2-aminopyridine and 2 mmol of 2-chloro-5-(chloromethyl)pyridine to 30 mL of tetrahydrofuran solvent, stir and mix, then add 0.1 mmol of sodium hydride, react at 55 °C for 2 h, then add 0.1 mol / L dilute hydrochloric acid to adjust the pH to neutral, wash, dry, and obtain intermediate 1;

[0056] The modified starch is prepared as follows: 4.5g of starch is added to a reaction flask containing 95mL of deionized water for dissolution, and then 6.5g of sodium periodate is added. The mixture is sonicated to form a starch slurry. 1mol / L hydrochloric acid is added to adjust the pH, and the mixture is heated to 32℃ for 3h. After the reaction is completed, 3.8g of ethylene glycol is added and stirred for 10min. Then, 1mol / L sodium hydroxide solution is added to adjust the pH to neutral. The mixture is filtered and washed with anhydrous ethanol to obtain the modified starch.

[0057] The preparation method of the plant insecticide is as follows: add intermediate 1, modified starch and sodium alginate into a stirrer and stir for 17 minutes to obtain the plant insecticide.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 4 is that no pyridine insecticide was added.

[0060] A plant-based insecticide comprising the following components by weight: 0.8 parts by weight of carvacrol, 3 parts by weight of modified starch, and 3 parts by weight of sodium alginate.

[0061] The modified starch is prepared as follows: 4.5g of starch is added to a reaction flask containing 95mL of deionized water for dissolution, and then 6.5g of sodium periodate is added. The mixture is sonicated to form a starch slurry. 1mol / L hydrochloric acid is added to adjust the pH, and the mixture is heated to 32℃ for 3h. After the reaction is completed, 3.8g of ethylene glycol is added and stirred for 10min. Then, 1mol / L sodium hydroxide solution is added to adjust the pH to neutral. The mixture is filtered and washed with anhydrous ethanol to obtain the modified starch.

[0062] The preparation method of the plant insecticide is as follows: add modified starch and sodium alginate into a stirrer and stir for 17 minutes to obtain the plant insecticide.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 4 is that no modified starch was added.

[0065] A plant-based insecticide comprising the following components by weight: 1 part by weight of pyridine insecticide, 0.8 parts by weight of carvacrol, 3 parts by weight of modified starch, and 3 parts by weight of sodium alginate.

[0066] The preparation method of the pyridine insecticide is as follows:

[0067] S1. Add 2 mmol of 2-aminopyridine and 2 mmol of 2-chloro-5-(chloromethyl)pyridine to 30 mL of tetrahydrofuran solvent, stir and mix, then add 0.1 mmol of sodium hydride, react at 55 °C for 2 h, then add 0.1 mol / L dilute hydrochloric acid to adjust the pH to neutral, wash, dry, and obtain intermediate 1;

[0068] S2. Add 0.34 g of 6-chloro-1-hexanol and 2.6 mmol of intermediate 1 to 40 mL of N,N-dimethylformamide solvent, stir to dissolve, react at 65 °C for 3 h, and then distill under reduced pressure and wash to obtain pyridine insecticide.

[0069] The preparation method of the plant insecticide is as follows: add pyridine insecticide and sodium alginate into a stirrer and stir for 17 minutes to obtain the plant insecticide.

[0070] Performance testing

[0071] Test method: The insecticide was diluted 2500 times (by weight) with water and sprayed. Application was carried out between 7:00 AM and 9:00 AM when cowpeas were flowering. The insecticide was evenly sprayed onto the front and back surfaces of the cowpea plants, flowers, and leaves. The application rate was 675 kg / hm², and the application was repeated once. The control group was sprayed with an equal amount of water. Eight plots were defined: seven experimental groups and one control group, each plot measuring 20 m². 2 Five sampling points were used in each plot, with two plants surveyed at each point, for a total of 10 plants. Five leaves from the middle and upper parts of each plant were surveyed to determine the number of thrips. The experiment was conducted twice, once before the application and once 10 days after the application. The control effect was calculated using the following formulas: Thrips population reduction rate (%) = (Number of nymphs before application - Number of nymphs after application) / Number of nymphs before application × 100; Control effect (%) = (Pest population reduction rate in the experimental group - Pest population reduction rate in the control group) / (100 - Pest population reduction rate in the control group) × 100.

[0072] Table 1: Prevention and Control Effects

[0073]

[0074] As shown in Table 1, the insecticide of the present invention has a good insecticidal effect.

[0075] Comparative Example 1 uses only Intermediate 1 to replace the complete pyridine insecticide, lacking the hydroxyl group introduced in step S2. This prevents it from forming a synergistic film-forming effect with modified starch and sodium alginate. Furthermore, the insecticidal activity of Intermediate 1 is lower than that of the complete pyridine insecticide, resulting in a significant decrease in efficacy. Comparative Example 2 completely lacks pyridine insecticide, relying solely on the single activity of carvacrol. Carvacrol itself has limited insecticidal activity, failing to meet the requirements for high-efficiency control, and lacks synergistic active components with carvacrol, resulting in the worst efficacy. Comparative Example 3 lacks modified starch, failing to form a stable protective film. The active ingredients are easily washed away and volatilized by rainwater. Although there is a synergistic effect between the complete pyridine insecticide and carvacrol, the low retention rate of active components leads to a decrease in efficacy.

[0076] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0078] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A plant-based insecticide, characterized in that, It comprises the following weight components: 1-2 parts by weight of pyridine insecticide, 0.8-1 parts by weight of carvacrol, 3-5 parts by weight of modified starch, 3-4.5 parts by weight of sodium alginate; The structure of the pyridine insecticide is: The preparation method of the pyridine insecticide is: S1. Add 2-aminopyridine and 2-chloro-5-(chloromethyl)pyridine to tetrahydrofuran solvent, stir and mix, continue to add sodium hydride, react at 55-60℃ for 2-4h, then add dilute hydrochloric acid to adjust pH to neutral, wash and dry to obtain intermediate 1; S2. Add 6-chloro-1-hexanol and intermediate 1 to N,N-dimethylformamide solvent, stir and dissolve, react at 60-65℃ for 2-3h, then distill under reduced pressure, wash to obtain pyridine insecticide; In S1, the amount ratio of 2-aminopyridine, 2-chloro-5-(chloromethyl)pyridine and sodium hydride is 2-3mmol:2-3mmol:0.1-0.2mmol; In S2, the amount ratio of 6-chloro-1-hexanol and intermediate 1 is 0.27-0.34g:2-2.6mmol; The preparation method of the modified starch is: take starch and add it to a reaction bottle containing deionized water for dissolution, then continue to add sodium periodate, ultrasonically form a starch milk, add 1mol / L hydrochloric acid to adjust pH, heat and react for 2-4h, then add ethylene glycol, stir for 8-12min, then add 1mol / L sodium hydroxide solution to adjust pH to neutral, suction filter, wash with anhydrous ethanol to obtain modified starch; The amount ratio of the starch, deionized water, sodium periodate and ethylene glycol is 4-5g:90-100mL:6.3-6.7g:3.6-3.9g; The heating temperature for the heating reaction of 2-4h is 30-35℃.

2. A process for the preparation of a plant insecticide as claimed in claim 1, wherein, The preparation method of the plant insecticide is: add pyridine insecticide, modified starch and sodium alginate to a stirrer, stir for 15-20min to obtain a plant insecticide.

Images