A composite fungicide and preparation process

Abstract

The present invention relates to the technical field of fungicides, and discloses a composite fungicide and a preparation process. The composite fungicide comprises the following components: a benzothiazole oxadiazole fungicide, a triazole fungicide, an antifreeze agent, and a surfactant. The benzothiazole oxadiazole fungicide has certain inhibitory activity against pathogenic fungi such as wheat fusarium head blight and rice sheath blight. The benzothiazole oxadiazole fungicide is compounded with triazole fungicides such as metconazole and propanthazole, and surfactants such as alkylphenol polyoxyethylene ether phosphate to obtain a composite fungicide. The benzothiazole oxadiazole fungicide and the triazole fungicide complement and enhance synergy, exhibiting excellent inhibitory and killing effects against pathogenic fungi such as wheat fusarium head blight and rice sheath blight, and having the advantages of low usage concentration and good broad spectrum.

Description

Technical Field

[0001] The present invention relates to the technical field of fungicides, in particular to a composite fungicide and a preparation process. Background Art

[0002] During the planting and growth process, crops such as wheat and rice are susceptible to diseases such as wheat ergot, wheat powdery mildew, and rice sheath blight, which can lead to crop yield reduction. Countries around the world are vigorously developing new agricultural fungicides; triazole fungicides such as metconazole and propidazole have strong inhibitory activity against a variety of fungal pathogens such as the Ascomycota and Deuteromycota, and are a common type of agricultural fungicide.

[0003] Compounding triazole fungicides with antibacterial substances such as miconazole, isothiazolinone, and oxadiazole can achieve even better bactericidal effects. Patent CN104488907B discloses compounding 2-(p-fluorophenyl)-5-methylsulfonyl-1,3,4-oxadiazole with prothioconazole to create a fungicide that can control various crop diseases, including tomato bacterial wilt, melon wilt, and peanut leaf spot. The present invention aims to compound triazole fungicides with benzothiazole oxadiazole fungicides for the control of various crop diseases, including wheat fusarium head blight. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a composite fungicide with high-efficiency inhibitory effect on fungi such as wheat fusarium sphaeroides and rice sheath blight.

[0005] The technical solution provided by the present invention is:

[0006] A composite fungicide comprising the following components in parts by weight: 100 parts of a benzothiazole oxadiazole fungicide, 20-30 parts of an antifreeze agent, 30-80 parts of a triazole fungicide, and 8-20 parts of a surfactant;

[0007] The structural formula of the benzothiazole oxadiazole fungicide is: ;

[0008] The R1 group is 1-F, 2-F, 3-F or 4-F; the R2 group is 3-F, 4-F, 3-CF3 or 4-CF3.

[0009] Furthermore, the triazole fungicide includes one or a combination of myclobutanil, metconazole, bisbenzisin, propanthazole, and fluopicolide.

[0010] Furthermore, the preparation process of the composite fungicide comprises the following steps:

[0011] S1. Adding benzothiazole hydrazide intermediate and fluorinated benzaldehyde derivative to ethanol, wherein the structural formula of the fluorinated benzaldehyde derivative is , R2 group is 3-F, 4-F, 3-CF3 or 4-CF3; stirring and dissolving, stirring and reflux at 70-80 °C for 3-8 h, cooling, rotary evaporation, washing with ether, and recrystallization of the product from ethanol to obtain a benzothiazole hydrazide imine intermediate;

[0012] S2. In an ice bath, add benzothiazole hydrazide imine intermediate and N-bromosuccinimide to dichloromethane, stir and react for 1-3 hours, then add triethylamine at 20-35°C, stir and react for 1-2 hours, rotary evaporate, wash with ether, and recrystallize the product from ethanol to obtain a benzothiazole oxadiazole fungicide;

[0013] S3. Add benzothiazole oxadiazole fungicide, triazole fungicide and surfactant into distilled water, stir and disperse, and obtain a composite fungicide.

[0014] Furthermore, the ratio of the benzothiazole hydrazide intermediate and the fluorinated benzaldehyde derivative in S1 is 1 mol: (0.8-1.4) mol.

[0015] Furthermore, the ratio of the benzothiazole hydrazide imine intermediate, N-bromosuccinimide, and triethylamine in S2 is 1 mol: (5-7.5) mol: (2.5-3.8) mol.

[0016] Furthermore, the preparation process of the benzothiazole hydrazide intermediate comprises the following steps:

[0017] S11, adding a fluorine-containing aminobenzothiazole derivative, succinic anhydride and pyridine to dichloromethane, wherein the structural formula of the fluorine-containing aminobenzothiazole derivative is , R1 group is 1-F, 2-F, 3-F or 4-F; the reaction is carried out at a temperature of 10-25°C for 6-12 h, rotary evaporated, washed with diethyl ether, and the product is added to thionyl chloride, stirred and refluxed at 65-80°C for 2-4 h, rotary evaporated, washed with diethyl ether, and dried to obtain a fluorinated benzothiazole chloride intermediate.

[0018] S12. In an ice bath, add the fluorinated benzothiazole chloride intermediate, hydrazine hydrate, and triethylamine to tetrahydrofuran, stir and react for 2-4 h, rotary evaporate, wash with ether, and recrystallize the product from ethyl acetate to obtain the benzothiazole hydrazide intermediate.

[0019] Furthermore, the ratio of the fluorine-containing aminobenzothiazole derivative, succinic anhydride and pyridine is 1 mol: (1.2-1.5) mol: (1.5-2.2) mol.

[0020] The technical effects produced by the present invention are:

[0021] The present invention uses fluorine-containing aminobenzothiazole derivatives, succinic anhydride, hydrazine hydrate, fluorine-containing benzaldehyde derivatives and the like as reactants to prepare a class of biologically active benzothiazole oxadiazole fungicides, which have certain inhibitory activity against pathogenic fungi such as wheat fusarium sphaeroides and rice sheath blight.

[0022] The present invention compounds a benzothiazole oxadiazole fungicide with triazole fungicides such as metconazole and propanol, and surfactants such as alkylphenol polyoxyethylene ether phosphate to obtain a composite fungicide. The benzothiazole oxadiazole fungicide and the triazole fungicide play a complementary and synergistic role, exhibiting excellent inhibitory and killing effects on pathogenic fungi such as wheat fusarium rust and rice sheath blight, and having the advantages of low usage concentration and good broad spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a reaction route for preparing benzothiazole oxadiazole fungicides. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] To 30-50 mL of dichloromethane was added 5 mmol of a fluorinated aminobenzothiazole derivative (structural formula: , R1 group is 1-F, 2-F, 3-F or 4-F), 6-7.5 mmol succinic anhydride and 7.5-11 mmol pyridine, react at 10-25°C for 6-12 h, rotary evaporation, wash with diethyl ether, add the product to 5-10 mL thionyl chloride, stir and reflux at 65-80°C for 2-4 h, rotary evaporation, wash with diethyl ether, and dry to obtain a fluorinated benzothiazole acid chloride intermediate.

[0026] In an ice bath, add 5 mmol of the fluorinated benzothiazole chloride intermediate, 2-3 mL of hydrazine hydrate, and 8-12 mmol of triethylamine to 30-50 mL of tetrahydrofuran. Stir and react for 2-4 h. Rotary evaporate, wash with ether, and recrystallize the product from ethyl acetate to obtain the benzothiazole hydrazide intermediate.

[0027] To 200-300 mL of ethanol, add 20 mmol of benzothiazole hydrazide intermediate and 16-28 mmol of fluorinated benzaldehyde derivative (structural formula: , R2 group is 3-F, 4-F, 3-CF3 or 4-CF3), stirred and dissolved, stirred and refluxed at 70-80 °C for 3-8 h, cooled, rotary evaporated, washed with ether, and the product was recrystallized from ethanol to obtain a benzothiazole hydrazide imine intermediate;

[0028] In an ice bath, add 10 mmol of the benzothiazole hydrazide imine intermediate and 50-75 mmol of N-bromosuccinimide to 200-300 mL of dichloromethane, and stir to react for 1-3 h. Then, add 25-38 mmol of triethylamine at 20-35 °C, stir to react for 1-2 h, rotary evaporate, wash with ether, and recrystallize the product from ethanol to obtain a benzothiazole oxadiazole fungicide.

[0029] Add 10g of benzothiazole oxadiazole fungicide, 3-8g of triazole fungicide, wherein the triazole fungicide includes one or a combination of myclobutanil, metconazole, bisbenzisinol, propanthazole, and fluopicolide, 2-3g of antifreeze agent ethylene glycol, 0.6-1.4g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.2-0.6g of surfactant Tween-80 to distilled water, stir and disperse, and obtain a composite fungicide.

[0030] Example 1

[0031] 5 mmol of 2-amino-4-fluorobenzothiazole (structural formula: ), 6 mmol succinic anhydride and 7.5 mmol pyridine, react at 10 ° C for 12 h, rotary evaporate, wash with ether, add the product into 5 mL thionyl chloride, stir and reflux at 70 ° C for 3 h, rotary evaporate, wash with ether, and dry to obtain a fluorinated benzothiazole acid chloride intermediate.

[0032] In an ice bath, 5 mmol of the fluorinated benzothiazole chloride intermediate, 2 mL of hydrazine hydrate, and 8 mmol of triethylamine were added to 30 mL of tetrahydrofuran. The mixture was stirred for 3 h, and the mixture was rotary evaporated, washed with ether, and the product was recrystallized from ethyl acetate to obtain the benzothiazole hydrazide intermediate.

[0033] To 300 mL of ethanol, 20 mmol of benzothiazole hydrazide intermediate and 28 mmol of 3-fluorobenzaldehyde (structural formula: ), stirred and dissolved, stirred and refluxed at 75 °C for 8 h, cooled, rotary evaporated, washed with ether, and the product was recrystallized from ethanol to obtain a benzothiazole hydrazide imine intermediate;

[0034] In an ice bath, add 10 mmol of benzothiazole hydrazide imine intermediate and 50 mmol of N-bromosuccinimide to 200 mL of dichloromethane and stir for 1 hour. Then add 25 mmol of triethylamine at 25°C and stir for 2 hours. Rotary evaporate, wash with ether, and recrystallize the product from ethanol to obtain benzothiazole oxadiazole fungicide. Molecular formula: C 18 H 12 F2N4O2S; 1 H NMR (300 MHz, CDCl3) δ 9.24 (s, 1H), 7.84-7.78 (m, 2H), 7.54-7.50 (m, 3H), 7.28-7.18 (m, 2H), 2.80-2.71 (m, 2H), 2.59-2.49 (m, 2H). Reaction scheme:

[0035] ;

[0036] Add 10 g of benzothiazole oxadiazole fungicide, 6 g of propanthazole, 2.5 g of antifreeze agent ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 to distilled water, stir and disperse, and obtain a composite fungicide.

[0037] Example 2

[0038] 5 mmol of 2-amino-5-fluorobenzothiazole (structural formula: ), 6.8 mmol succinic anhydride and 9.5 mmol pyridine, react at 25 ° C for 6 h, rotary evaporate, wash with ether, add the product into 8 mL thionyl chloride, stir and reflux at 80 ° C for 2 h, rotary evaporate, wash with ether, and dry to obtain a fluorinated benzothiazole chloride intermediate.

[0039] In an ice bath, 5 mmol of the fluorinated benzothiazole chloride intermediate, 3 mL of hydrazine hydrate, and 12 mmol of triethylamine were added to 50 mL of tetrahydrofuran. The mixture was stirred for 3 h, and the mixture was rotary evaporated, washed with ether, and the product was recrystallized from ethyl acetate to obtain the benzothiazole hydrazide intermediate.

[0040] To 200 mL of ethanol, 20 mmol of benzothiazole hydrazide intermediate and 16 mmol of 3-fluorobenzaldehyde (structural formula: ), stirred and dissolved, stirred and refluxed at 80 °C for 3 h, cooled, rotary evaporated, washed with ether, and the product was recrystallized from ethanol to obtain a benzothiazole hydrazide imine intermediate;

[0041] In an ice bath, add 10 mmol of benzothiazole hydrazide imine intermediate and 75 mmol of N-bromosuccinimide to 200 mL of dichloromethane and stir for 1 hour. Then add 38 mmol of triethylamine at 35 °C and stir for 2 hours. Rotary evaporate, wash with ether, and recrystallize the product from ethanol to obtain benzothiazole oxadiazole fungicide. Molecular formula: C 18 H 12 F2N4O2S; 1 H NMR (300 MHz, CDCl3) δ 9.20 (s, 1H), 7.94-7.80 (m, 3H), 7.56-7.50 (m, 2H), 7.26-7.17 (m, 2H), 2.83-2.74 (m, 2H), 2.59-2.50 (m, 2H). Reaction scheme:

[0042] ;

[0043] Add 10 g of benzothiazole oxadiazole fungicide, 6 g of propanthazole, 2.5 g of antifreeze agent ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 to distilled water, stir and disperse, and obtain a composite fungicide.

[0044] Example 3

[0045] 5 mmol of 2-amino-6-fluorobenzothiazole (structural formula: ), 7.5 mmol succinic anhydride and 11 mmol pyridine, react at 15 ° C for 8 h, rotary evaporate, wash with ether, add the product into 10 mL thionyl chloride, stir and reflux at 65 ° C for 4 h, rotary evaporate, wash with ether, and dry to obtain a fluorinated benzothiazole acid chloride intermediate.

[0046] In an ice bath, 5 mmol of the fluorinated benzothiazole chloride intermediate, 2.5 mL of hydrazine hydrate, and 10 mmol of triethylamine were added to 40 mL of tetrahydrofuran. The mixture was stirred for 4 h, and the mixture was rotary evaporated. The mixture was washed with ether, and the product was recrystallized from ethyl acetate to obtain the benzothiazole hydrazide intermediate.

[0047] To 250 mL of ethanol, 20 mmol of benzothiazole hydrazide intermediate and 20 mmol of 3-fluorobenzaldehyde (structural formula: ), stirred and dissolved, stirred and refluxed at 80 °C for 3 h, cooled, rotary evaporated, washed with ether, and the product was recrystallized from ethanol to obtain a benzothiazole hydrazide imine intermediate;

[0048] In an ice bath, add 10 mmol of benzothiazole hydrazide imine intermediate and 50 mmol of N-bromosuccinimide to 200 mL of dichloromethane and stir for 1 hour. Then add 25 mmol of triethylamine at 25°C and stir for 2 hours. Rotary evaporate, wash with ether, and recrystallize the product from ethanol to obtain benzothiazole oxadiazole fungicide. Molecular formula: C 18 H 12 F2N4O2S; 1 H NMR (300 MHz, CDCl3) δ 9.18 (s, 1H), 8.05-7.81 (m, 3H), 7.51-7.48 (m, 2H), 7.26-7.19 (m, 2H), 2.85-2.75 (m, 2H), 2.59-2.51 (m, 2H). Reaction scheme:

[0049] ;

[0050] Add 10 g of benzothiazole oxadiazole fungicide, 6 g of propanthazole, 2.5 g of antifreeze agent ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 to distilled water, stir and disperse, and obtain a composite fungicide.

[0051] Example 4

[0052] Preparation of fluorinated benzothiazole chloride intermediate: the same method as in Example 2.

[0053] Preparation of benzothiazole hydrazide intermediate: the same method as in Example 2.

[0054] To 250 mL of ethanol, 20 mmol of benzothiazole hydrazide intermediate and 16 mmol of 4-fluorobenzaldehyde (structural formula: ), stirred and dissolved, stirred and refluxed at 70 °C for 8 h, cooled, rotary evaporated, washed with ether, and the product was recrystallized from ethanol to obtain a benzothiazole hydrazide imine intermediate;

[0055] In an ice bath, add 10 mmol of benzothiazole hydrazide imine intermediate and 62 mmol of N-bromosuccinimide to 300 mL of dichloromethane and stir for 2 h. Then add 30 mmol of triethylamine at 25 °C and stir for 1 h. Rotary evaporate, wash with ether, and recrystallize the product from ethanol to obtain a benzothiazole oxadiazole fungicide. Molecular formula: C 18 H 12 F2N4O2S; 1H NMR (300 MHz, CDCl3) δ 9.18 (s, 1H), 8.20-8.13 (m, 2H), 7.99-7.88 (m, 2H), 7.30-7.22 (m, 3H), 2.86-2.75 (m, 2H), 2.62-2.52 (m, 2H). Reaction scheme:

[0056] ;

[0057] Add 10 g of benzothiazole oxadiazole fungicide, 6 g of propanthazole, 2.5 g of antifreeze agent ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 to distilled water, stir and disperse, and obtain a composite fungicide.

[0058] Example 5

[0059] Preparation of fluorinated benzothiazole chloride intermediate: the same method as in Example 2.

[0060] Preparation of benzothiazole hydrazide intermediate: the same method as in Example 2.

[0061] To 200 mL of ethanol, 20 mmol of benzothiazole hydrazide intermediate and 20 mmol of 4-trifluoromethylbenzaldehyde (structural formula: ), stirred and dissolved, stirred and refluxed at 70 °C for 8 h, cooled, rotary evaporated, washed with ether, and the product was recrystallized from ethanol to obtain a benzothiazole hydrazide imine intermediate;

[0062] In an ice bath, add 10 mmol of benzothiazole hydrazide imine intermediate and 75 mmol of N-bromosuccinimide to 300 mL of dichloromethane and stir for 2 h. Then add 38 mmol of triethylamine at 20°C and stir for 2 h. Rotary evaporate, wash with ether, and recrystallize the product in ethanol to obtain benzothiazole oxadiazole fungicide. Molecular formula: C 19 H 12 F4N4O2S; 1 H NMR (300 MHz, CDCl3) δ 9.14 (s, 1H), 8.05-7.92 (m, 4H), 7.71-7.65 (m, 2H), 7.26-7.20 (m, 1H), 2.85-2.75 (m, 2H), 2.58-2.49 (m, 2H). Reaction scheme:

[0063] ;

[0064] Add 10 g of benzothiazole oxadiazole fungicide, 6 g of propanthazole, 2.5 g of antifreeze agent ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 to distilled water, stir and disperse, and obtain a composite fungicide.

[0065] Example 6

[0066] Preparation of fluorinated benzothiazole chloride intermediate: the same method as in Example 2.

[0067] Preparation of benzothiazole hydrazide intermediate: the same method as in Example 2.

[0068] To 250 mL of ethanol, 20 mmol of benzothiazole hydrazide intermediate and 20 mmol of 3-trifluoromethylbenzaldehyde (structural formula: ), stirred and dissolved, stirred and refluxed at 75 °C for 4 h, cooled, rotary evaporated, washed with ether, and the product was recrystallized from ethanol to obtain a benzothiazole hydrazide imine intermediate;

[0069] In an ice bath, add 10 mmol of benzothiazole hydrazide imine intermediate and 62 mmol of N-bromosuccinimide to 250 mL of dichloromethane and stir for 2 h. Then add 30 mmol of triethylamine at 35 °C and stir for 2 h. Rotary evaporate, wash with ether, and recrystallize the product from ethanol to obtain a benzothiazole oxadiazole fungicide. Molecular formula: C 19 H 12 F4N4O2S; 1 H NMR (300 MHz, CDCl3) δ 9.14 (s, 1H), 8.02-7.90 (m, 4H), 7.56-7.25 (m, 3H), 2.83-2.75 (m, 2H), 2.57-2.48 (m, 2H) Reaction route:

[0070] ;

[0071] Add 10 g of benzothiazole oxadiazole fungicide, 6 g of propanthazole, 2.5 g of antifreeze agent ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 to distilled water, stir and disperse, and obtain a composite fungicide.

[0072] Sterilization performance test:

[0073] The benzothiazole oxadiazole fungicide (10 g) prepared in Examples 1-6, 2.5 g of antifreeze ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 were placed in a volumetric flask, and sterile distilled water was added to dilute the solution to the fixed volume using an isocratic dilution method until the concentration of the benzothiazole oxadiazole fungicide in the solution reached 2.44 mg / L. This was used as a fungicide solution.

[0074] 6 g of propanthazole, 2.5 g of antifreeze ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 were placed in a volumetric flask, and sterilized distilled water was added to dilute and fix the volume. The isocratic dilution method was used until the concentration of the benzothiazole oxadiazole fungicide in the solution reached 2.44 mg / L, which was used as the fungicide solution.

[0075] AEA medium: 7 g agar, 2.5 g yeast extract, 3 g sodium sulfite, 0.8 g potassium dihydrogen phosphate, 0.25 g potassium chloride, 0.5 g, 0.12 g magnesium sulfate, 10 mL glycerol, and 500 mL sterile distilled water.

[0076] Gibberella fusca and Rhizoctonia solani were used as test pathogens. The pathogens were activated at 25°C for 12 hours, and a 4mm diameter bacterial cake was prepared using a microporator. This cake was inoculated into AEA medium containing a fungicide solution to form the experimental group. A control group, sterile distilled water without a fungicide, was used. The culture was incubated in an incubator at 25°C for 96 hours, and colony diameters were measured using the cross-hatch method.

[0077] Inhibition rate = (AB) / A×100%, A is the colony diameter of the control group, and B is the colony diameter of the experimental group.

[0078]

[0079] The benzothiazole oxadiazole fungicide (10 g) prepared in Examples 1-6, 6 g of propanthazole, 2.5 g of antifreeze ethylene glycol, 1 g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4 g of surfactant Tween-80 were placed in a volumetric flask, and sterile distilled water was added to dilute the solution to the fixed volume using an isocratic dilution method until the concentration of the benzothiazole oxadiazole fungicide in the solution was 2.44 mg / L and the concentration of the propanthazole was 1.46 mg / L, thereby preparing the fungicide solution.

[0080] Gibberella fusca and Rhizoctonia solani were used as test pathogens. The pathogens were activated at 25°C for 12 hours, and a 4mm diameter bacterial cake was prepared using a microporator. This cake was inoculated into AEA medium containing a fungicide solution to form the experimental group. A control group, sterile distilled water without a fungicide, was used. The culture was incubated in an incubator at 25°C for 96 hours, and colony diameters were measured using the cross-hatch method.

[0081]

[0082] Weigh 10g of the benzothiazole oxadiazole fungicide (structural formula) prepared in Example 5. ), 6g of triazole fungicide (the triazole fungicide is any one of myclobutanil, metconazole, bisbenzisinol, propanil, and fluopicolide), 2.5g of antifreeze ethylene glycol, 1g of surfactant alkylphenol polyoxyethylene ether phosphate, and 0.4g of surfactant Tween-80 are placed in a volumetric flask, and sterilized distilled water is added to dilute and fix the volume. The isocratic dilution method is used until the concentration of the benzothiazole oxadiazole fungicide in the solution is 2.44mg / L and the concentration of propanil is 1.46mg / L, which are used as the fungicide solution.

[0083] Gibberella fusca and Rhizoctonia solani were used as test pathogens. The pathogens were activated at 25°C for 12 hours, and a 4mm diameter bacterial cake was prepared using a microporator. This cake was inoculated into AEA medium containing a fungicide solution to form the experimental group. A control group, sterile distilled water without a fungicide, was used. The culture was incubated in an incubator at 25°C for 96 hours, and colony diameters were measured using the cross-hatch method.

[0084]

[0085] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A composite fungicide, characterized in that: The composite fungicide comprises the following components in parts by weight: 100 parts of benzothiazole oxadiazole fungicide, 30-80 parts of triazole fungicide, 20-30 parts of antifreeze agent, and 8-20 parts of surfactant; The structural formula of the benzothiazole oxadiazole fungicide is: ; The R1 group is 1-F, 2-F, 3-F or 4-F; the R2 group is 3-F, 4-F, 3-CF3 or 4-CF3; the triazole fungicide includes one or a combination of myclobutanil, metconazole, bisbenzisone, propanthazole and fluopicolide.

2. A process for preparing the composite fungicide according to claim 1, characterized in that: The steps include: S1. Add the benzothiazole hydrazide intermediate and the fluorinated benzaldehyde derivative to ethanol, stir and dissolve, stir and reflux at 70-80°C for 3-8 hours, cool, rotary evaporate, wash, and recrystallize to obtain the benzothiazole hydrazide imine intermediate; S2. Add benzothiazole hydrazide imine intermediate and N-bromosuccinimide to dichloromethane under ice bath, stir and react for 1-3 h, then add triethylamine at 20-35°C, stir and react for 1-2 h, rotary evaporate, wash, and recrystallize to obtain benzothiazole oxadiazole fungicide; S3, adding benzothiazole oxadiazole fungicide, triazole fungicide, antifreeze agent, and surfactant to distilled water, stirring and dispersing, to obtain a composite fungicide; The structural formula of the fluorinated benzaldehyde derivative in S1 is , the R2 group is 3-F, 4-F, 3-CF3 or 4-CF3; The preparation process of the benzothiazole hydrazide intermediate comprises the following steps: S11. Add a fluorinated aminobenzothiazole derivative, succinic anhydride, and pyridine to dichloromethane, react at 10-25°C for 6-12 hours, rotary evaporate, wash, add the product to thionyl chloride, stir and reflux at 65-80°C for 2-4 hours, rotary evaporate, wash, and dry to obtain a fluorinated benzothiazole chloride intermediate; S12. In an ice bath, add the fluorinated benzothiazole chloride intermediate, hydrazine hydrate, and triethylamine to tetrahydrofuran, stir and react for 2-4 h, rotary evaporate, wash, and recrystallize to obtain the benzothiazole hydrazide intermediate; The structural formula of the fluorine-containing aminobenzothiazole derivative is , the R1 group is 1-F, 2-F, 3-F or 4-F.

3. The preparation process of the composite fungicide according to claim 2, characterized in that: The ratio of the benzothiazole hydrazide intermediate to the fluorinated benzaldehyde derivative in S1 is 1 mol: (0.8-1.4) mol.

4. The preparation process of the composite fungicide according to claim 2, characterized in that: The ratio of the benzothiazole hydrazide imine intermediate, N-bromosuccinimide and triethylamine in S2 is 1 mol: (5-7.5) mol: (2.5-3.8) mol.

5. The preparation process of the composite fungicide according to claim 2, characterized in that: The ratio of the fluorine-containing aminobenzothiazole derivative to succinic anhydride and pyridine is 1 mol: (1.2-1.5) mol: (1.5-2.2) mol.

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