Photosensitive herbicide as well as preparation method and application thereof
By introducing a photosensitive linker into the herbicide, which maintains low activity at night and releases active ingredients in a directed manner under light, the problems of the impact of traditional herbicides on non-target organisms and slow efficacy are solved, achieving a balance between weed control effect and ecological safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- QUNLI CHEM SHANGHAI
- Filing Date
- 2026-03-26
- Publication Date
- 2026-05-05
AI Technical Summary
Traditional herbicides can easily affect non-target organisms when applied during the day, impacting biodiversity and ecological balance. At night, the herbicides are slow to take effect due to environmental limitations, resulting in reduced control effectiveness.
A photosensitive herbicide is designed by introducing a photosensitive linker between the herbicidal active group and the growth-inhibiting regulatory group, so that the herbicide maintains low activity at night and then releases the active ingredient through directional cleavage under light conditions, thereby achieving spatiotemporal matching between the herbicide's efficacy and the photosynthesis of weeds.
To improve the absorption efficiency and efficacy of pesticides, reduce the impact on non-target organisms, and enhance the ecological safety and sustainability of agricultural production.
Smart Images
Figure CN121974880A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of herbicide technology, specifically to a photosensitive herbicide, its preparation method, and its application. Background Technology
[0002] Competition from weeds is a major factor affecting crop yield and the stability of agro-ecosystems. Traditional herbicides are mostly applied during the day, which, while beneficial for their activity and faster action under sufficient sunlight, coincides with the peak activity of various pollinating insects and beneficial arthropods. This increases the risk of exposure to non-target organisms, thus impacting biodiversity and ecological balance. In contrast, nighttime application avoids pollinating insect activity to some extent, reducing ecological disturbance and offering better environmental friendliness. However, insufficient light, lower temperatures, and heavy dew at night often inhibit the biological activity of some herbicides. The physiological differences in diurnal rhythms between crops and weeds also affect herbicide absorption and translocation, missing the most active photosynthetic period in weeds, weakening the absorption and translocation efficiency of herbicides, leading to delayed efficacy or even reduced control effects.
[0003] Therefore, how to ensure weed control while also taking ecological safety into account has become an important issue that urgently needs to be addressed in modern agricultural green management. Summary of the Invention
[0004] (a) Purpose of the invention The purpose of this invention is to provide a photosensitive herbicide, its preparation method, and its application. Through a photosensitive connecting arm, the herbicide is in a stable, low-activity state after nighttime application. Under subsequent light conditions, it undergoes directional cleavage and precisely releases the active ingredients, thereby achieving spatiotemporal matching between the release of the herbicide and the active period of weed photosynthesis. This significantly improves the utilization efficiency of pesticides and reduces the impact on other organisms.
[0005] (II) Technical Solution To address the above problems, the present invention provides a photosensitive herbicide, comprising: the general formula structure of the photosensitive herbicide: ALB, wherein: A is a coumarin-based herbicidal active group; B is a growth-inhibiting regulatory group, which is an abscisic acid analog or a salicylic acid derivative; L is a photosensitive linker, which includes an azophenyl group or an o-nitrobenzyl group, and is cleaved under light irradiation at a wavelength of 365-450 nm.
[0006] In another aspect of the present invention, preferably, the coumarin-based herbicidal active group includes 7-hydroxy-4-methylcoumarin or its halogenated derivatives; The photosensitive linker is connected to group A and group B via ester bonds or amide bonds, respectively.
[0007] In another aspect, preferably, a method for preparing a photosensitive herbicide is applicable to preparing the photosensitive herbicide as described above, the preparation method comprising: The first intermediate is obtained by reacting a carboxyl-containing azophenyl group or an ortho-nitrobenzyl group with thionyl chloride. The coumarin-based herbicidal active group is esterified with the first intermediate to obtain the second intermediate; The growth-inhibiting regulatory group was reacted with the second intermediate in a condensing agent system, and the photosensitive herbicide was obtained by column chromatography purification.
[0008] In another aspect of the present invention, preferably, the reaction of a carboxyl-containing azophenyl group or o-nitrobenzyl group with thionyl chloride to obtain the first intermediate comprises: A carboxyl-containing azobenzene derivative or o-nitrobenzyl derivative is mixed with thionyl chloride at a first preset molar ratio to obtain a first mixture; N,N-dimethylformamide was added to the first mixture to obtain a second mixture; The second mixture is subjected to a reflux reaction under a first preset condition to obtain a third mixture; The third mixture was purified by vacuum distillation to obtain the first intermediate.
[0009] In another aspect of the present invention, preferably, the first preset molar ratio is 1:(1.2 to 5.0); the first preset conditions include: a reflux temperature of 60°C to 80°C, and a reflux time of 2 to 6 hours.
[0010] In another aspect of the present invention, preferably, the esterification reaction of the coumarin-based herbicidal active group with the first intermediate to obtain the second intermediate comprises: The coumarin-based herbicidal active groups are dissolved in an organic solvent, and an organic base and catalyst are added to obtain a first substrate solution. Under a second preset condition, the first intermediate is added dropwise to the first substrate solution to obtain a second substrate solution; Under the third preset conditions, the second substrate solution is stirred to obtain the third substrate solution; The third substrate solution is purified to obtain the second intermediate.
[0011] In another aspect of the present invention, preferably, the molar ratio of the first intermediate to the coumarin-based herbicidal active group is 1:(1.0 to 1.5); The organic solvent includes dichloromethane, tetrahydrofuran, or acetonitrile; The organic base includes triethylamine, pyridine, or N,N-diisopropylethylamine; The catalyst includes 4-dimethylaminopyridine; The second preset conditions include: a temperature of 0℃ to 5℃ and a dropping time of 1 to 2 hours; The third preset conditions include: room temperature and stirring time of 4 to 12 hours.
[0012] In another aspect of the present invention, preferably, the step of reacting the growth-inhibiting regulatory group with the second intermediate in a condensing agent system and purifying the photosensitive herbicide by column chromatography comprises: The second intermediate, growth inhibition regulating group, organic solvent, condensing agent and auxiliary catalyst are mixed to obtain the first reaction mixture; Under the fourth preset condition, the first reaction mixture is stirred to obtain the second reaction mixture; The second reaction mixture is purified to obtain a third reaction mixture; The third reaction mixture was purified by column chromatography using an eluent to obtain a photosensitizing herbicide.
[0013] In another aspect of the present invention, preferably, the molar ratio of the second intermediate to the growth inhibition regulating group is 1:(1.0 to 1.5); The organic solvent includes dichloromethane, tetrahydrofuran, or acetonitrile; The condensing agent includes EDCI, DCC, or HATU; The auxiliary catalyst includes DMAP or triethylamine; The fourth preset condition includes: stirring at 0℃~5℃ for 0.5~2h, then raising the temperature to room temperature and stirring for 6~24h.
[0014] In another aspect of the present invention, preferably, is the application of a photosensitive herbicide as described above, or a photosensitive herbicide prepared by the photosensitive herbicide preparation method as described above, in the control of weeds.
[0015] (III) Beneficial Effects The above-described technical solution of the present invention has the following beneficial technical effects: This invention introduces a photosensitive linker between the herbicidal active group and the growth-inhibiting regulatory group, enabling the herbicide to remain structurally stable and in a low-activity state after nighttime application, thereby reducing the risk of exposure to non-target organisms and environmental burden at the source. Under natural light or specific wavelengths of light, the photosensitive linker undergoes controlled cleavage, precisely releasing the herbicidal active ingredient. This achieves spatiotemporal matching of herbicide release with the active photosynthetic period of weeds, significantly improving herbicide absorption efficiency and efficacy. The growth-inhibiting regulatory group further interferes with the physiological metabolic processes of weeds, enhancing the integrated pest management effect. While ensuring weed control, it effectively reduces the impact on pollinating insects and other beneficial organisms, improving the ecological safety and sustainability of agricultural production. Attached Figure Description
[0016] Figure 1 This is an overall flowchart of one embodiment of the present invention. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.
[0018] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0019] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0020] Example A photosensitive herbicide, comprising: the general formula structure of the photosensitive herbicide: ALB, wherein: A represents a coumarin-based herbicidal active group, which includes 7-hydroxy-4-methylcoumarin or its halogenated derivatives. In the halogenated derivatives, the halogen substituents can be fluorine, chlorine, or bromine, and can exert herbicidal effects by interfering with electron transfer in plants or inducing the generation of reactive oxygen species.
[0021] B is a growth-inhibiting regulatory group, which is an abscisic acid analog or a salicylic acid derivative. When B is an abscisic acid analog, its structure may include a cyclohexenone skeleton and a side-chain carboxyl structural unit. When B is a salicylic acid derivative, its structure includes an o-hydroxybenzoic acid skeleton and may contain alkyl, halogen, or nitro substituents. The B group enhances the synergistic effect of weed control by regulating plant hormone signaling pathways and inhibiting cell division and elongation.
[0022] L is the photosensitive linker arm, which includes an azophenyl group or an o-nitrobenzyl group. Under irradiation with light at a wavelength of 365-450 nm, the photosensitive linker arm is cleaved and connected to groups A and B via ester or amide bonds, respectively. In photosensitive herbicides, when group A is 7-hydroxy-4-methylcoumarin or its halogenated derivative, an ester bond is formed through esterification between its 7-position phenolic hydroxyl group (-OH) and the carboxyl group or its activated derivative at one end of the photosensitive linker arm L. When group A is modified by amination, an amide bond can also be formed between the 7-position amino group and the carboxyl group at the L end. When group B is an abscisic acid analog or a salicylic acid derivative, an ester or amide bond is formed through reaction between its carboxyl group (-COOH) and the hydroxyl or amino group at the other end of the photosensitive linker arm L. In abscisic acid analogs, the carboxyl group on its side chain participates in the bonding, while in salicylic acid derivatives, the carboxyl group on its benzene ring participates in the bonding. The photosensitive linker L is a bifunctional molecule containing azobenzene or o-nitrobenzyl structural units, with carboxyl, hydroxyl or amino functional groups at both ends that can react with hydroxyl or carboxyl groups, thus forming an AO-CO-LO-CO-B or AO-CO-L-NH-CO-B linkage in the molecular structure.
[0023] Under ultraviolet to visible light (365-450nm) irradiation, the photosensitive linker undergoes photochemical cleavage: when L is an o-nitrobenzyl structure, a photoinduced rearrangement reaction occurs, leading to the breakage of ester or amide bonds; when L is an azobenzene structure, cis-trans isomerization occurs and bond dissociation is induced. After the photosensitive linker cleaves, A and B are released as free active molecules, thereby simultaneously producing herbicidal and growth-inhibiting effects, achieving photo-triggered synergistic activation. By introducing a photosensitive linker between the herbicidal active group and the growth-inhibiting regulatory group, the herbicide remains structurally stable and in a low-activity state after nighttime application, reducing the risk of exposure to non-target organisms and environmental burden from the source. Under natural light or specific wavelength light conditions, the photosensitive linker undergoes controlled cleavage, precisely releasing the herbicidal active ingredient, achieving spatiotemporal matching between herbicide release and the active period of weed photosynthesis, thus significantly improving herbicide absorption efficiency and efficacy.
[0024] Furthermore, this embodiment also provides a method for preparing a photosensitive herbicide. Figure 1 An overall flowchart of one embodiment of the present invention is shown, as follows: Figure 1As shown, the preparation method for the above-mentioned photosensitive herbicide includes: The first intermediate is obtained by reacting a carboxyl-containing azophenyl group or an o-nitrobenzyl group with thionyl chloride, comprising: A carboxyl-containing azobenzene derivative or o-nitrobenzyl derivative is mixed with thionyl chloride at a first preset molar ratio to obtain a first mixture. The first preset molar ratio is 1:(1.2 to 5.0). The excess of thionyl chloride helps to promote the conversion of carboxyl groups to acyl chloride and also facilitates the complete reaction.
[0025] N,N-Dimethylformamide is added to the first mixture to obtain a second mixture. N,N-Dimethylformamide acts as a reaction promoter, and its addition amount is 0.5% to 5% of the first mixture by volume. It can activate the carboxyl group and generate a more reactive intermediate activator, thereby improving the acyl chloride reaction rate and conversion efficiency.
[0026] The second mixture is subjected to reflux reaction under the first preset conditions to obtain the third mixture. The first preset conditions include: reflux temperature of 60℃~80℃ and reflux time of 2~6h.
[0027] The third mixture was purified by vacuum distillation to obtain the first intermediate. The pressure was gradually reduced at 40°C to 70°C to gently remove excess thionyl chloride and volatile byproducts generated during the reaction, thus avoiding the decomposition of the first intermediate.
[0028] The coumarin herbicidal active group is esterified with the first intermediate to obtain the second intermediate, which includes: Coumarin herbicidal active groups are dissolved in an organic solvent, and an organic base and catalyst are added to obtain a first substrate solution. The organic solvent includes dichloromethane, tetrahydrofuran, or acetonitrile, with 5–50 volume parts of organic solvent added per mole of coumarin herbicidal active group. The organic base includes triethylamine, pyridine, or N,N-diisopropylethylamine, and the catalyst includes 4-dimethylaminopyridine. The organic base is used to neutralize acidic byproducts generated during the reaction and maintain an alkaline environment in the reaction system. The molar ratio of coumarin herbicidal active groups to organic base is 1:(1.0–2.0). The organic base absorbs acidic byproducts generated during the esterification reaction and maintains a weakly alkaline environment in the reaction system, thereby promoting ester bond formation and increasing the reaction conversion rate. The molar ratio of coumarin herbicidal active groups to the catalyst 4-dimethylaminopyridine is 1:(0.01–0.20) to promote ester bond formation.
[0029] Under the second preset conditions, the first intermediate is added dropwise to the first substrate solution to obtain the second substrate solution; the second preset conditions include: a temperature of 0℃~5℃, a dropping time of 1~2h, and a molar ratio of the first intermediate to the coumarin herbicidal active group of 1:(1.0~1.5). Under the third preset conditions, the second substrate solution is stirred to obtain the third substrate solution. The third preset conditions include: room temperature, stirring time of 4 to 12 hours, and room temperature of 20°C to 25°C.
[0030] The third substrate solution is purified to obtain the second intermediate. Purification removes unreacted raw materials, organic base salts, catalyst residues, and byproducts. A saturated salt (NaCl) solution can be used. The organic phase and aqueous phase are thoroughly stirred to ensure full contact. The mixture is then allowed to stand and separate into layers. The upper organic phase is then separated to obtain the second intermediate.
[0031] The growth-inhibiting regulatory group is reacted with a second intermediate in a condensing agent system, and the resulting photosensitive herbicide is purified by column chromatography, comprising: The second intermediate, growth inhibition regulating group, organic solvent, condensing agent and auxiliary catalyst are mixed to obtain a first reaction mixture; the molar ratio of the second intermediate to the growth inhibition regulating group is 1:(1.0-1.5); the organic solvent includes dichloromethane, tetrahydrofuran or acetonitrile; the condensing agent includes EDCI, DCC or HATU; the auxiliary catalyst includes DMAP or triethylamine; each mole of the second intermediate corresponds to about 5-50 volumes of organic solvent; the molar ratio of the second intermediate to the condensing agent is 1:(0.9-1.5); and the molar ratio of the second intermediate to the auxiliary catalyst is 1:(0.01-0.20).
[0032] Under the fourth preset conditions, the first reaction mixture is stirred to obtain the second reaction mixture; the fourth preset conditions include: stirring at 0℃~5℃ for 0.5~2h and then heating to room temperature and stirring for 6~24h, with the room temperature being 20℃~25℃.
[0033] The second reaction mixture is purified to obtain a third reaction mixture. Water or a saturated salt (NaCl) solution is added to the second reaction mixture, and the mixture is stirred thoroughly at room temperature to transfer water-soluble impurities, such as unreacted growth-inhibiting regulatory groups, condensation agent byproducts, and some auxiliary catalyst residues, to the aqueous phase. After standing and separating the layers, the organic phase is separated. Washing can be repeated 1 to 3 times to ensure that impurities in the organic phase are removed as much as possible.
[0034] The third reaction mixture was purified by column chromatography using an eluent to obtain a photosensitizing herbicide. The eluent was a gradient of petroleum ether and ethyl acetate or a gradient of chloroform and methanol, and the volume ratio of the third reaction mixture to the eluent was 1:(10–50) to achieve effective separation of the target product from impurities, resulting in a high-purity photosensitizing herbicide.
[0035] Furthermore, this embodiment also provides the application of the above-mentioned photosensitive herbicide, or the photosensitive herbicide prepared by the above-mentioned photosensitive herbicide preparation method, in weed control.
[0036] Example 1 A photosensitive herbicide, wherein A is 7-hydroxy-4-methylcoumarin, B is an abscisic acid analogue, namely methyl abscisic acid, and L is an azophenyl group as the photosensitive linker arm.
[0037] Preparation methods include: A carboxyl-containing azobenzene derivative and thionyl chloride were mixed at a ratio of 1:3 to obtain a first mixture. N,N-dimethylformamide was added to the first mixture to obtain a second mixture, wherein the amount of N,N-dimethylformamide added was 3% of the volume of the first mixture. The second mixture was refluxed at 70°C for 4 hours to obtain a third mixture. The third mixture was purified by vacuum distillation, with the pressure gradually reduced at 50°C to obtain a first intermediate.
[0038] 7-Hydroxy-4-methylcoumarin was dissolved in dichloromethane, and triethylamine and 4-dimethylaminopyridine were added to obtain the first substrate solution. The amount of dichloromethane added was 30 parts by volume for every 1 mole of 7-hydroxy-4-methylcoumarin, with a molar ratio of 7-hydroxy-4-methylcoumarin to triethylamine of 1:1.5 and a molar ratio of 7-hydroxy-4-methylcoumarin to 4-dimethylaminopyridine of 1:0.1. The first intermediate was added dropwise to the first substrate solution at 3°C for 1.5 h to obtain the second substrate solution. The molar ratio of the first intermediate to 7-hydroxy-4-methylcoumarin was 1:1.2. The second substrate solution was stirred at 22°C for 8 h to obtain the third substrate solution. The third substrate solution was purified using a saturated salt (NaCl) solution to obtain the second intermediate.
[0039] The second intermediate, methyl abscisic acid, dichloromethane, EDCI, and DMAP were mixed to obtain the first reaction mixture. Approximately 30 volumes of dichloromethane were used for every 1 mole of the second intermediate. The molar ratio of the second intermediate to EDCI was 1:1.2, and the molar ratio of the second intermediate to DMAP was 1:0.1. The mixture was stirred at 3°C for 1 hour, then heated to 22°C and stirred for 18 hours to obtain the second reaction mixture. The second reaction mixture was then purified using a saturated salt (NaCl) solution to obtain the third reaction mixture. The third reaction mixture was purified by column chromatography using a gradient of petroleum ether and ethyl acetate, with a volume ratio of 1:30 between the third reaction mixture and the petroleum ether and ethyl acetate gradient, to obtain a photosensitizing herbicide.
[0040] Example 2 A photosensitive herbicide, wherein A is 7-hydroxy-4-methylcoumarin, B is a salicylic acid derivative, namely 5-nitrosalicylic acid, and L is an o-nitrobenzyl group as the photosensitive linker arm.
[0041] Preparation methods include: o-Nitrobenzyl derivative and thionyl chloride were mixed at a ratio of 1:5 to obtain a first mixture. N,N-dimethylformamide was added to the first mixture to obtain a second mixture, wherein the amount of N,N-dimethylformamide added was 5% of the volume of the first mixture. The second mixture was refluxed at 80°C for 2 hours to obtain a third mixture. The third mixture was purified by vacuum distillation, with the pressure gradually reduced at 70°C to obtain a first intermediate.
[0042] 7-Hydroxy-4-methylcoumarin was dissolved in tetrahydrofuran, and pyridine and 4-dimethylaminopyridine were added to obtain the first substrate solution. The amount of tetrahydrofuran added was 50 parts by volume for every 1 mole of 7-hydroxy-4-methylcoumarin, with a molar ratio of 7-hydroxy-4-methylcoumarin to pyridine of 1:2 and a molar ratio of 7-hydroxy-4-methylcoumarin to 4-dimethylaminopyridine of 1:0.2. The first intermediate was added dropwise to the first substrate solution at 5°C for 2 hours to obtain the second substrate solution. The molar ratio of the first intermediate to 7-hydroxy-4-methylcoumarin was 1:1.5. The second substrate solution was stirred at 25°C for 12 hours to obtain the third substrate solution. The third substrate solution was purified using a saturated salt (NaCl) solution to obtain the second intermediate.
[0043] The second intermediate, 5-nitrosalicylic acid, tetrahydrofuran, DCC, and triethylamine were mixed to obtain the first reaction mixture. Each mole of the second intermediate corresponded to approximately 50 volumes of tetrahydrofuran. The molar ratio of the second intermediate to DCC was 1:1.5, and the molar ratio of the second intermediate to triethylamine was 1:0.2. The mixture was stirred at 5°C for 2 hours, then heated to 25°C and stirred for 24 hours to obtain the second reaction mixture. The second reaction mixture was then purified using a saturated salt (NaCl) solution to obtain the third reaction mixture. The third reaction mixture was purified by column chromatography using a chloroform and methanol gradient, with a volume ratio of 1:50 between the third reaction mixture and the chloroform and methanol gradient, to obtain a photosensitive herbicide.
[0044] Example 3 A photosensitive herbicide, wherein A is a halogenated derivative of 7-hydroxy-4-methylcoumarin, namely 6-chloro-7-hydroxy-4-methylcoumarin, B is an abscisic acid analog, namely racemic abscisic acid, and L is an azophenyl group as the photosensitive linker arm.
[0045] Preparation methods include: A carboxyl-containing azobenzene derivative and thionyl chloride were mixed at a ratio of 1:1.2 to obtain a first mixture. N,N-dimethylformamide was added to the first mixture to obtain a second mixture, wherein the amount of N,N-dimethylformamide added was 0.5% of the volume of the first mixture. The second mixture was refluxed at 60°C for 6 hours to obtain a third mixture. The third mixture was purified by vacuum distillation, with the pressure gradually reduced at 40°C to obtain a first intermediate.
[0046] 6-Chloro-7-hydroxy-4-methylcoumarin was dissolved in acetonitrile, and N,N-diisopropylethylamine and 4-dimethylaminopyridine were added to obtain a first substrate solution. The amount of acetonitrile added was 5 volumes of acetonitrile per 1 mole of 6-chloro-7-hydroxy-4-methylcoumarin, with a molar ratio of 6-chloro-7-hydroxy-4-methylcoumarin to N,N-diisopropylethylamine of 1:1 and a molar ratio of 6-chloro-7-hydroxy-4-methylcoumarin to 4-dimethylaminopyridine of 1:0.01. The first intermediate was added dropwise to the first substrate solution at 0°C for 1 hour to obtain a second substrate solution. The molar ratio of the first intermediate to 6-chloro-7-hydroxy-4-methylcoumarin was 1:1. The second substrate solution was stirred at 20°C for 4 hours to obtain a third substrate solution. The third substrate solution was purified using a saturated salt (NaCl) solution to obtain the second intermediate.
[0047] The second intermediate, racemic abscisic acid, acetonitrile, HATU, and DMAP were mixed to obtain the first reaction mixture. Approximately 5 volume parts of acetonitrile were present for every 1 mole of the second intermediate. The molar ratio of the second intermediate to HATU was 1:0.9, and the molar ratio of the second intermediate to DMAP was 1:0.01. The mixture was stirred at 0°C for 0.5 h, then heated to 20°C and stirred for 6 h to obtain the second reaction mixture. The second reaction mixture was then purified using a saturated salt (NaCl) solution to obtain the third reaction mixture. The third reaction mixture was purified by column chromatography using a gradient of petroleum ether and ethyl acetate, with a volume ratio of 1:10 between the third reaction mixture and the petroleum ether and ethyl acetate gradient, to obtain a photosensitive herbicide.
[0048] Comparative Example 1 7-Hydroxy-4-methylcoumarin and methyl abscisic acid, applied during the day.
[0049] Comparative Example 2 Apply 7-hydroxy-4-methylcoumarin and methyl abscisic acid at night.
[0050] Comparative Example 3 7-Hydroxy-4-methylcoumarin, applied during the day.
[0051] Experiments were conducted using Examples 1-3 and Comparative Examples 1-3 in wheat fields under uniform cultivation and management conditions. The weeds used were annual broadleaf weeds such as cleavers, purslane, and amaranth. The experimental fields were selected with flat terrain and uniform growth. A randomized block design was used to set up multiple treatment plots, with a 10-20m interval between each treatment plot. Untreated buffer zones of at least 5m wide were set up between adjacent plots to reduce pesticide drift and interference from cross-regional activities of pollinating insects. Examples 1-3 and Comparative Examples 1-3 were each set up with three replicates. The same active ingredient dosage was applied. Examples 1-3 were applied within 1 hour after sunset, Comparative Examples 1 and 3 were applied during the day, and Comparative Example 2 was applied at night. The weed fresh weight inhibition rate was investigated on days 1, 3, and 7 after application of the pesticide. The number of pollinating insect visits and the changes in the types of pollinating insects per unit time in each treatment plot were recorded at fixed time periods (9:00 to 11:00) every day. Table 1 shows the experimental results of Examples 1-3 and Comparative Examples 1-2: Table 1. Test results of Examples 1-3 and Comparative Examples 1-3 As shown in Table 1, Examples 1-3 all exhibited stable and high herbicidal effects under nighttime application conditions. The herbicidal rates at 7 and 14 days were comparable to those of Comparative Example 1 (applied during the day) and significantly better than Comparative Example 2 (applied at night without the introduction of a photosensitive structure). Furthermore, Examples 1-3 only caused slight fluctuations in pollinating insect activity 3 days after application, which largely recovered after 7 days, indicating minimal interference with beneficial organisms. Comparative Example 1 showed some herbicidal effect but significantly impacted daytime insects; Comparative Example 2 had less impact on insects but insufficient herbicidal effect; Comparative Example 3, containing only 7-hydroxy-4-methylcoumarin, had a lower herbicidal green content, and daytime application significantly affected daytime insects.
[0052] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.
[0053] The present invention has been described above with reference to embodiments thereof. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.
[0054] Although embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and modifications can be made to the embodiments of the present invention without departing from the spirit and scope of the invention.
[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A photosensitive herbicide, characterized in that, include: The general formula of the photosensitive herbicide is: ALB, wherein: A is a coumarin-based herbicidal active group; B is a growth-inhibiting regulatory group, which is an abscisic acid analog or a salicylic acid derivative; L is a photosensitive linker, which includes an azophenyl group or an o-nitrobenzyl group, and is cleaved under light irradiation at a wavelength of 365-450 nm.
2. The photosensitive herbicide according to claim 1, characterized in that, The coumarin-based herbicidal active group includes 7-hydroxy-4-methylcoumarin or its halogenated derivatives; The photosensitive linker is connected to group A and group B via ester bonds or amide bonds, respectively.
3. A method for preparing a photosensitive herbicide, characterized in that: Suitable for preparing the photosensitive herbicide as described in claim 1 or 2, the preparation method comprising: The first intermediate is obtained by reacting a carboxyl-containing azophenyl group or an ortho-nitrobenzyl group with thionyl chloride. The coumarin-based herbicidal active group is esterified with the first intermediate to obtain the second intermediate; The growth-inhibiting regulatory group was reacted with the second intermediate in a condensing agent system, and the photosensitive herbicide was obtained by column chromatography purification.
4. The preparation method according to claim 3, characterized in that: The reaction of a carboxyl-containing azophenyl group or an o-nitrobenzyl group with thionyl chloride to obtain the first intermediate includes: A carboxyl-containing azobenzene derivative or o-nitrobenzyl derivative is mixed with thionyl chloride at a first preset molar ratio to obtain a first mixture; N,N-dimethylformamide was added to the first mixture to obtain a second mixture; The second mixture is subjected to a reflux reaction under a first preset condition to obtain a third mixture; The third mixture was purified by vacuum distillation to obtain the first intermediate.
5. The preparation method according to claim 4, characterized in that: The first preset molar ratio is 1:(1.2~5.0); the first preset conditions include: reflux temperature of 60℃~80℃, and reflux time of 2~6h.
6. The preparation method according to claim 5, characterized in that: The step of esterifying the coumarin-based herbicidal active group with the first intermediate to obtain the second intermediate includes: The coumarin-based herbicidal active groups are dissolved in an organic solvent, and an organic base and catalyst are added to obtain a first substrate solution. Under a second preset condition, the first intermediate is added dropwise to the first substrate solution to obtain a second substrate solution; Under the third preset conditions, the second substrate solution is stirred to obtain the third substrate solution; The third substrate solution is purified to obtain the second intermediate.
7. The preparation method according to claim 6, characterized in that: The molar ratio of the first intermediate to the coumarin-based herbicidal active group is 1:(1.0-1.5); The organic solvent includes dichloromethane, tetrahydrofuran, or acetonitrile; The organic base includes triethylamine, pyridine, or N,N-diisopropylethylamine; The catalyst includes 4-dimethylaminopyridine; The second preset conditions include: a temperature of 0℃ to 5℃ and a dropping time of 1 to 2 hours; The third preset conditions include: room temperature and stirring time of 4 to 12 hours.
8. The preparation method according to claim 7, characterized in that: The process of reacting the growth-inhibiting regulatory group with the second intermediate in a condensing agent system, followed by column chromatography purification to obtain the photosensitive herbicide, comprises: The second intermediate, growth inhibition regulating group, organic solvent, condensing agent and auxiliary catalyst are mixed to obtain the first reaction mixture; Under the fourth preset condition, the first reaction mixture is stirred to obtain the second reaction mixture; The second reaction mixture is purified to obtain a third reaction mixture; The third reaction mixture was purified by column chromatography using an eluent to obtain a photosensitizing herbicide.
9. The preparation method according to claim 8, characterized in that: The molar ratio of the second intermediate to the growth-inhibiting regulatory group is 1:(1.0–1.5); The organic solvent includes dichloromethane, tetrahydrofuran, or acetonitrile; The condensing agent includes EDCI, DCC, or HATU; The auxiliary catalyst includes DMAP or triethylamine; The fourth preset condition includes: stirring at 0℃~5℃ for 0.5~2h, then raising the temperature to room temperature and stirring for 6~24h.
10. The application of a photosensitive herbicide as described in claim 1 or 2, or a photosensitive herbicide prepared by the method described in any one of claims 3-9, in the control of weeds.