A method of predicting and preparing a metabolite of trifloxysulfuron

Abstract

The application discloses a kind of triflufensulfuron-methyl metabolite prediction and preparation method, it is related to pesticide detection technical field, including M-1, M-2 and M-3;Wherein the structural formula of M-1: the structural formula of M-2: the structural formula of M-3: the application further provides the preparation method of triflufensulfuron-methyl main metabolite M-1, M-2 and M-3, the determination of its synthetic method is conducive to further carry out triflufensulfuron-methyl main metabolite in the adsorption / desorption of environment, leaching, migration and conversion environmental behavior research and to aquatic organisms (zebrafish, black shell shrimp), terrestrial animals (red aposhechens earthworm) and amphibian (tadpole) acute toxicity and chronic toxicity mechanism research.

Description

Technical Field

[0001] This invention relates to the field of pesticide detection technology, specifically a method for predicting and preparing trifluralin metabolites. Background Technology

[0002] Tiafenacil, a novel ureapyridine herbicide, was jointly developed in 2012 by Booamuk Hannong of South Korea and ISK Bioscience of Japan. Its molecule contains an amide and pyrimidine dione structure with a β-amino acid backbone, making it a protoporphyrinogen oxidase (PPO) inhibitor. It has attracted considerable attention due to its significant potential as a replacement for glyphosate in the control of monocotyledonous and dicotyledonous weeds. It was registered in South Korea in 2017 for the control of annual and perennial weeds. Tiafenacil targets chlorophyll in plant cells, ensuring selective toxicity between plants and animals. It features low dosage, high activity, broad spectrum of weed control, low toxicity to mammals, and minimal environmental impact. In 2019, commissioned by Booamuk Hannong of South Korea, we conducted a two-year, five-location field efficacy and residue trial of Tiafenacil in China prior to its registration. The results showed that both 5% trifluralin suspension concentrate and 70% trifluralin water-dispersible granules effectively controlled grasses and broadleaf weeds in citrus orchards. They also demonstrated excellent control efficacy against glyphosate-resistant weeds such as goosegrass and tufted grass, exhibiting rapid action and a long residual effect of up to 30 days. The dissipation half-life in five different types of citrus orchard soils ranged from 0.26 to 5.11 days, indicating that trifluralin is a readily degradable pesticide with no adverse effects on citrus tree growth and shows great promise for application. Recent research shows that the degradation process of this pesticide produces metabolites with potential toxicity to non-target organisms, mainly M-1, M-2, and M-3 (chemical structural formulas are shown in...). Figure 1 Compared to other degradation products, M-2 is the most persistent and harmful in aquatic environments. Triflumethrin has been granted a patent in my country, but its registration and promotion have not yet been approved by the Ministry of Agriculture and Rural Affairs. Furthermore, the applicant has discovered that triflumethrin possesses excellent biological activity and great development potential. However, because the degradation of triflumethrin produces metabolites M-1, M-2, and M-3, which have potential toxicity to non-target organisms, the adsorption / desorption and migration behavior of triflumethrin and its metabolites in soil is a fundamental scientific question worthy of further investigation. Moreover, there are currently no reports on the preparation of triflumethrin and its metabolites. Summary of the Invention

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a method for predicting and preparing trifluralin metabolites.

[0004] The technical solution of the present invention is as follows:

[0005] A trifluralin metabolite comprising M-1, M-2, and M-3;

[0006] The structural formula of M-1 is:

[0007] The structural formula of M-2:

[0008] M-3 structural formula:

[0009] The present invention also discloses a method for preparing triflusulfonamide metabolites. Triflusulfonamide solution is taken, methanol is added, ultrapure water and sodium hydroxide are added, and the reaction is carried out under light-protected conditions for 20-24 hours. After the NaOH is completely consumed, methanol is removed by rotary evaporation, and dilute hydrochloric acid is added dropwise to adjust the pH of the solution to 2.5-3.5. The reaction is monitored by TLC until it is complete, and the product M-1 is obtained by filtration and separation.

[0010] Furthermore, the concentration of the dilute hydrochloric acid is 0.5-1.5 mol / L.

[0011] This invention also discloses a method for preparing triflusulfonamide metabolites. A triflusulfonamide solution is taken, concentrated hydrochloric acid and glacial acetic acid are added, and the mixture is heated in an oil bath at 70-85℃ for 20-24 hours. The reaction is monitored by TLC until complete. The pH of the solution is adjusted to 4-6, and the solution is extracted with ethyl acetate. The ethyl acetate is removed by rotary evaporation, and the product M-2 is obtained by drying.

[0012] This invention also discloses a method for preparing trifluralinsulfuron-methyl metabolites. Under ice bath conditions, a dichloromethane solution containing oxalyl chloride is slowly added dropwise to a dichloromethane solution containing M-2. After reacting for 3-5 hours, the M-2 acyl chloride compound obtained by rotary evaporation is dissolved in an appropriate amount of dichloromethane to obtain a dichloromethane solution of M-2 acyl chloride for later use.

[0013] Under ice bath conditions, a dichloromethane solution of M-2 acyl chloride was slowly added dropwise to methanol and a dichloromethane solution of triethylamine / pyridine. The reaction was carried out for 3-5 hours. After the reaction was confirmed to be complete by chromatographic detection, the dichloromethane solution containing M-2 methyl ester was back-extracted. The back-extract was collected, concentrated ammonia was added and stirred, and the solution was extracted with ethyl acetate, then rotary evaporated and dried to obtain the degradation product M-3.

[0014] As a preferred embodiment of the present invention, the molar ratio of M2, methanol and triethylamine is 1:1.02:2.

[0015] This invention also discloses a method for predicting triflumethrin metabolites. The method uses density functional theory to predict and describe the molecular structural characteristics of triflumethrin. First, the molecular electrostatic potential of triflumethrin in pure water is calculated, the preferred positions of electrophilic and nucleophilic reactions of triflumethrin are predicted, the favorable positions of electrostatically dominated non-covalent interactions of triflumethrin are inferred, and then the metabolites produced by triflumethrin are calculated.

[0016] The beneficial effects of this invention are: This invention provides a method for preparing the main metabolites M-1, M-2 and M-3 of triflusulfonamide. The determination of the synthesis method is conducive to further research on the environmental behavior of the main metabolites of triflusulfonamide in the environment, including adsorption / desorption, leaching, migration and transformation, as well as the mechanism of acute and chronic toxicity to aquatic organisms (zebrafish, black shrimp), terrestrial animals (Eisenia fetida), and amphibians (tadpoles). Attached Figure Description

[0017] Figure 1 The chemical structures and transformation pathways of trifluralinsulfuron and M-1, M-2, and M-3 were deduced.

[0018] Figure 2 The synthetic route for M-1, the conversion product of triflusulfuron;

[0019] Figure 3 The synthetic route for M-2, the conversion product of triflusulfuron;

[0020] Figure 4 The synthetic route for M-3, the conversion product of trifluralinsulfuron;

[0021] Figure 5 The graphs represent the positive (A) and negative (B) phase regions of the molecular electrostatic potential (MEP) of trifluralinsulfuron (the color scale range is -6.138 to 6.138 e). -2 );

[0022] Figure 6 Positive phase (A), negative phase (B), positive phase (C), negative phase (D) of the HOMO orbital wave function of triflusulfonamide; 3D structural model of triflusulfonamide (E).

[0023] Figure 7 (A) is a comparison of the 1H NMR spectra of triflusulfonamide and its conversion products M-1, M-2, and M-3, and (B) is a comparison of the 13C NMR spectra of triflusulfonamide and its conversion products M-1, M-2, and M-3.

[0024] Figure 8 Comparison of infrared spectra of trifluralinsulfuron and its conversion products M-1, M-2, and M-3. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0026] It should be noted that TLC mentioned in this application refers to thin-layer chromatography.

[0027] Concentrated hydrochloric acid 12.1 mol / L, glacial acetic acid 17.5 mol / L, and concentrated ammonia solution 22-25 wt%.

[0028] Example 1

[0029] Synthesis of conversion product M1: 1.0000 g (accurate to 0.0001 g) of trifluralin sulfate standard (purity: 98.4%) was placed in a 250 mL brown Erlenmeyer flask, followed by 50 mL of methanol, then 50 mL of ultrapure water and 0.160 g of sodium hydroxide. The mixture was shaken for 24 h at 25 °C in the dark. After the NaOH was completely consumed, the methanol was removed by rotary evaporation. The pH of the solution was adjusted to 3 by adding 1 mol / L dilute hydrochloric acid. The reaction was monitored by TLC until complete. The M1 precipitate was separated by filtration, with a yield of 90.36% (see...). Figure 2 ).

[0030] Example 2

[0031] Synthesis of conversion product M2: 1.0000 g (accurate to 0.0005 g) of trifluralin sulfate standard (purity: 98.4%) was placed in a round flask, and 10 mL of concentrated hydrochloric acid and 10 mL of glacial acetic acid were added. After incubation in an oil bath at 80 °C for 24 h, the reaction was monitored by TLC until complete. The pH of the solution was adjusted to weakly acidic, and the mixture was extracted with ethyl acetate. The ethyl acetate was removed by rotary evaporation, and the product M2 was obtained by drying, with a yield of 15.89% (see...). Figure 3 ).

[0032] Example 3

[0033] Synthesis of conversion product M3: Under ice bath conditions, a 10 mL dichloromethane solution containing 0.3 mL oxalyl chloride was slowly added dropwise to a 15 mL dichloromethane solution containing 0.4268 g M2 (with 2 drops of dimethylformamide DMF added beforehand). After reacting for 5 h, the M2 acyl chloride obtained by rotary evaporation was dissolved in an appropriate amount of dichloromethane for later use. Under ice bath conditions, the dichloromethane solution of M2 acyl chloride was slowly added dropwise to a dichloromethane solution of methanol and triethylamine / pyridine (M2:methanol:triethylamine = 1:1.02:2). After reacting for 5 h, and after chromatographic detection of complete reaction, the dichloromethane solution containing M2 methyl ester was back-extracted in the order of saturated sodium carbonate solution, saturated sodium chloride solution, and ultrapure water. The back-extract was collected, added to concentrated ammonia water and stirred, extracted with ethyl acetate, and then rotary evaporated and dried to obtain the degradation product M3, with a yield of 81.23% (see...). Figure 4 ).

[0034] Example 4

[0035] Density functional theory (DFT) was used to predict and describe the molecular structure of trifluralin, providing theoretical guidance for exploring its metabolic mechanism. First, the molecular electrostatic potential (MEP) of trifluralin in pure water was calculated, predicting the preferred sites for electrophilic and nucleophilic reactions and inferring the favorable sites for electrostatically dominant non-covalent interactions. This can be derived from... Figure 5 Intuitively, the positive phase region of trifluralin shows sites susceptible to electron attack, while the negative phase region shows sites susceptible to nucleophilic attack. For example... Figure 5 As shown, the oxygen atom should be the most favorable site for electrophilic attack, while the hydrogen atom on the triflumethrin dione moiety shows a very strong potential to attract negatively charged groups.

[0036] The transformation products and mechanisms of pesticides in soil are directly related to the soil environment. Constructing a method combining density functional theory (DFT) with non-targeted screening can provide a theoretical basis for identifying pesticide transformation products and elucidating their transformation mechanisms. Currently, high-resolution mass spectrometry is mainly used to analyze pesticide transformation products. However, for unstable intermediates and transformation products, transformation can occur during sample pretreatment or analysis, making it impossible for a single chemical analysis method to accurately and completely elucidate the pesticide transformation pathway. Therefore, this application proposes to construct a method combining non-targeted screening and density functional theory, which can not only compensate for the errors and uncertainties of experimental observations but also provide a theoretical basis for explaining the transformation process and a theoretical reference for pesticide environmental safety assessment and risk evaluation.

[0037] This application uses DFT to calculate the contributions of each atom of triflumethrin to the lowest vacant orbital (LUMO) and highest occupied orbital (HOMO). Figure 6 Analysis revealed that the pyrimidine dione structure in the trifluralin molecule is more susceptible to nucleophilic attacks (such as ·OH) leading to ring cleavage, while the amide structure is more susceptible to electrophilic attacks (such as H+). + Attacks by trifluralin (etc.) resulted in aminolysis or hydrolysis reactions; furthermore, non-targeted screening of transformation products of trifluralin in four citrus orchard soils showed that its main transformation products in purple soil were M-1, M-2, and M-3, with the inferred transformation pathway as follows: Figure 1 As shown in the figure. However, only M-1 and M-2 were found in red soil, yellow soil, and paddy soil, while M-3 was not observed. Other transformation products are yet to be identified. This indicates that different environmental conditions have different effects on pesticide degradation, with different transformation mechanisms and different impacts on the soil ecological environment.

[0038] By statistically analyzing the cumulative absolute values ​​of the natural charges of each atom in triflumirazine, we found that the absolute values ​​of natural charges of C(2), C(4), C(6), C(24) and N(26), N(41), N(42) are relatively high, making them sites susceptible to attack by nucleophiles or electrophiles. In addition, this application also calculated the bond order and bond length of the triflumirazine molecule; detailed values ​​are shown in Table 1. Generally, the smaller the bond order, the easier the chemical bond is to break; the longer the bond length, the easier the chemical bond is to break. The results show that the chemical bonds C(1)-C(6), C(1)-N(42), C(2)-N(41), C(4)-N(41), C(4)-N(47), C(24)-N(26), N(26)-C(28), and O(36)-C(37) are prone to breakage.

[0039] Table 1. Bond lengths and bond sequences of trifluralin at the DFT / B3LYP / 6-311G (2d, 2p) level.

[0040]

[0041] The structures of trifluralinsulfuron and the synthesized transformation products (M1, M2, and M3) were characterized by 1H NMR and 13C NMR using a JEOL ECX 500 NMR spectrometer. A comparison of the 1H NMR spectra of these four compounds in the DMSO-d6 system is shown below. Figure 7 The comparison of the carbon spectra (A) and 13C NMR is shown in the image. Figure 7 (B) Infrared spectral characterization is shown in [reference needed]. Figure 8 .

[0042] Recent research shows that the degradation process of this drug produces metabolites that have potential toxicity to non-target organisms, mainly M-1, M-2, and M-3 (chemical structural formulas are shown in [link to relevant documentation]). Figure 1 Compared to its parent compound, the metabolites exhibit the greatest persistence and harmfulness in the environment. Triflumethrin has been granted a patent in my country, but its registration and widespread application have not yet been approved by the Ministry of Agriculture and Rural Affairs. To address these issues, this application aims to conduct a study on the adsorption / desorption and migration behavior of triflumethrin and its main metabolites (M-1, M-2, M-3) in citrus orchard soil, in order to provide parameters for its registration, application, and risk assessment.

[0043] The determination of the synthesis method of this invention is conducive to further research on the environmental behavior of the main metabolites of triflusulfonamide in the environment, including adsorption / desorption, leaching, migration and transformation, as well as the mechanism of acute and chronic toxicity to aquatic organisms (zebrafish, black shrimp), terrestrial animals (Eisenia fetida), and amphibians (tadpoles).

[0044] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.

[0045] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A method for predicting triflusulfuron-methyl metabolites, characterized in that: The molecular structure characteristics of triflumethrin were predicted and described using density functional theory. First, the molecular electrostatic potential of triflumethrin in pure water was calculated, the preferred positions of electrophilic and nucleophilic reactions of triflumethrin were predicted, the favorable positions of electrostatically dominated non-covalent interactions of triflumethrin were inferred, and the metabolites produced by triflumethrin were then calculated. The specific prediction method is as follows: the contribution of each atom of triflumethinamide to the lowest empty orbital and the highest occupied orbital. The pyrimidine dione structure in the triflumethinamide molecule is more susceptible to nucleophilic attacks and ring-opening, while the amide structure is more susceptible to electrophilic attacks and undergoes aminolysis or hydrolysis reactions. By statistically analyzing the absolute values ​​of the cumulative natural charges of each atom in trifluralinsulfuron, it was found that C(2), C(4), C(6), C(24) and N(26), N(41), N(42) have relatively high absolute values ​​of natural charges, and are sites that are easily attacked by nucleophiles or electrophiles. The bond order and bond length of the trifluralin molecule were calculated. The smaller the bond order, the easier the chemical bond is to break; the longer the bond length, the easier the chemical bond is to break. The chemical bonds C(1)-C(6), C(1)-N(42), C(2)-N(41), C(4)-N(41), C(4)-N(47), C(24)-N(26), N(26)-C(28) and O(36)-C(37) are easy to break. The trifluralin metabolites are M-1, M-2, and M-3; The structural formula of M-1 is: ; The structural formula of M-2: ; M-3 structural formula: .

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