Dihalogenated phenyl succinamic acid and metal salt for nitrogen fertilizer synergist

Abstract

The invention discloses dihalogenated phenyl succinamic acid and metal salt for a nitrogen fertilizer synergist. The dihalogenated phenyl succinamic acid and the metal salt have a structure as shown in a formula 1, in the formula 1, R1-R6 are independently selected from H, Cl or F, only two groups in R1-R6 are F or Cl at the same time, and M is H, K or Na. The dihalogenated phenyl succinamic acid and the metal salt can effectively inhibit the activity of nitrifying bacteria in soil, reduce the conversion of ammonium nitrogen to nitrate nitrogen, and inhibit the decomposition of urease on urea and other nitrogen fertilizers, so that the nitrogen fertilizers can be more absorbed and utilized by crops, the utilization rate of the nitrogen fertilizers is remarkably improved, the nitrogen loss is reduced, and the agricultural production benefits are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of nitrogen fertilizer additives, in particular to dihalogenated phenyl succinamic acid and a metal salt used as nitrogen fertilizer synergists. Background Art

[0002] Nitrogenous fertilizer is a type of unit fertilizer with nitrogen (N) as the main component and the nitrogen content is clearly marked on its packaging or instructions. It can provide nitrogen nutrition to plants when applied to the soil. It is mainly divided into ammonium nitrogen fertilizer (such as ammonium sulfate, ammonium chloride, ammonium bicarbonate, etc.), nitrate nitrogen fertilizer (such as sodium nitrate, calcium nitrate, ammonium nitrate, etc.), ammonium nitrate nitrogen fertilizer (such as ammonium nitrate, calcium ammonium nitrate, ammonium sulfate nitrate, etc.) and amide nitrogen fertilizer (such as urea, urea formaldehyde and butylidene diurea, etc.). It plays an important role in agricultural production and has a significant effect on promoting crop root development, increasing tiller number, increasing chlorophyll content, improving soil structure, and enhancing soil fertility, thereby effectively improving the overall yield and quality of crops (Chawla, R., & Kumar Sharma, S. (2025). Nitrogen fertilization of stone fruits: A comprehensive review. Journal of Plant Nutrition, 48 (3), 445-485.). However, the utilization rate of traditional nitrogen fertilizers in agricultural production is low and it is easy to cause environmental pollution. The main reason is that ammonium nitrogen in the soil will be converted into nitrate nitrogen under the action of nitrifying bacteria, and nitrate nitrogen is extremely easy to be lost through leaching and dissolution, especially during rainfall or irrigation. In addition, the urease present in the soil will catalyze the rapid decomposition of nitrogen fertilizers such as urea into ammonium nitrogen and volatilize it in the form of ammonia gas (Lebrun, M., Védère, C., Honvault, N., Rumpel, C., & Houben, D. (2024). Mixing ratio and Nitrogen fertilization drive synergistic effects between biochar and compost. Nutrient Cycling in Agroecosystems, 128 (3), 429-446.). Therefore, it is particularly important to effectively inhibit the activity of nitrifying bacteria and urease in the soil.

[0003] Nitrogen fertilizer synergists, a class of organic compounds with unique properties and functions, play a vital role in agricultural production. Their mechanisms of action are primarily manifested in two aspects: on the one hand, some nitrogen fertilizer synergists are toxic to nitrifying bacteria; on the other hand, some nitrogen fertilizer synergists can effectively inhibit the activity of urease. When added to nitrogen fertilizers and applied to soil, nitrogen fertilizer synergists can improve nitrogen fertilizer utilization efficiency by inhibiting the nitrification of ammonium nitrogen by nitrifying bacteria in the soil or preventing the catalytic decomposition of nitrogen fertilizers such as urea by urease.

[0004] Currently, a variety of nitrogen fertilizer synergists are available on the market. However, these existing products are not perfect and present numerous issues that require improvement. Specifically, some products fail to meet the expected performance and cannot fully meet the actual needs of agricultural production. Some products are relatively expensive, which increases agricultural input costs and affects the economic benefits of agricultural production. Finally, some products lack stability, resulting in unstable results during actual use, which in turn affects the reliability and sustainability of agricultural production.

[0005] Given the above-mentioned shortcomings of existing nitrogen fertilizer synergists, it is particularly urgent and important to develop a nitrogen fertilizer synergist that is both efficient, environmentally friendly, and economical. This has important practical significance for promoting the sustainable development of agriculture and improving agricultural production efficiency. Summary of the Invention

[0006] The present invention aims to provide a dihalogenated phenyl succinamic acid and a metal salt thereof as nitrogen fertilizer synergists, so as to improve the utilization efficiency of nitrogen fertilizer.

[0007] The purpose of the present invention is achieved by the following technical solutions:

[0008] A dihalogenated phenyl succinamic acid and a metal salt for use as a nitrogen fertilizer synergist, wherein the dihalogenated phenyl succinamic acid and the metal salt have a structure as shown in Formula 1.

[0009] Formula 1:

[0010] Wherein, R1-R6 are each independently selected from H, Cl or F, and only two of R1-R6 are F or Cl at the same time, and M is H, K or Na.

[0011] In one specific embodiment, the dihalogenated phenylsuccinamic acid and metal salt used as nitrogen fertilizer synergist are selected from one of Compounds 1 to 54, as shown in Table 1.

[0012] Table 1

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021] According to the molecular structures of the 54 compounds shown in Table 1, the molecular formulas of the dihalogenated phenylsuccinamic acid and its metal salts involved in the present invention have the following characteristics:

[0022] (1) When the halogen atom in the structure of dihalogenated phenyl succinamide acid is a chlorine atom, regardless of the position of the chlorine atom on the molecule, the molecular formula is C 10 H9Cl2NO3, molecular weight is 262.09Dalton.

[0023] (2) When the halogen atom in the structure of potassium dihalogenophenyl succinamate is a chlorine atom, regardless of the position of the chlorine atom on the molecule, the molecular formula is C 10 H8C l2 KNO3, molecular weight is 300.18 Dalton.

[0024] (3) When the halogen atom in the structure of sodium dihalogenophenyl succinamate is a chlorine atom, regardless of the position of the chlorine atom on the molecule, the molecular formula is C 10 H8Cl2NNaO3, molecular weight is 284.07Dalton.

[0025] (4) When the halogen atom in the structure of dihalogenated phenyl succinamic acid is a fluorine atom, the molecular formula is C 10 H9F2NO3, molecular weight is 229.18Dalton.

[0026] (5) When the halogen atom in the structure of potassium dihalogenophenyl succinamate is a fluorine atom, regardless of the position of the fluorine atom on the molecule, the molecular formula is C 10 H8F2KNO3, molecular weight is 267.27Dalton.

[0027] (6) When the halogen atom of the structure is fluorine, the molecular formula is C 10 H8F2NNaO3, and the molecular weight is 251.16 Dalton.

[0028] The dihalophenyl succinamide acid has moderate water solubility and moisture absorption, but the moisture absorption is significantly enhanced after being compounded with nitrogen fertilizer. The moisture absorption property makes the dihalophenyl succinamide acid-containing nitrogen fertilizer more easily adsorbed by soil particles, effectively reducing the leaching and volatilization of N (nitrogen). By preparing the dihalophenyl succinamide acid into K (potassium) or Na (sodium) salt, the water solubility can be increased to about 5%, which is beneficial to the dissolution, release and uniform dispersion in the soil, thereby better exerting the effect. At the same time, the moisture absorption of the salt is also significantly improved, and there is no significant difference in the physicochemical properties between K (potassium) and Na (sodium) salts, and there is also no significant difference in the physicochemical properties between chlorine and fluorine. According to the demand of crops for nutrients, K (potassium) or Na (sodium) salt can be selected.

[0029] In a specific embodiment, the dihalophenyl succinamide acid and metal salt are selected from compound 3, compound 12, compound 21, compound 28, compound 31, compound 37, compound 40, compound 46 or compound 49;

[0030]

[0031]

[0032] A preparation method of the dihalophenyl succinamide acid and metal salt according to any one of the preceding embodiments,

[0033]

[0034] When M is H, the preparation method comprises: mixing a solvent, a compound shown in formula 2 and succinic anhydride (CAS number is 108-30-5) to react to obtain a compound shown in formula 3. The volume (m 3 ) of the solvent and the kilomole (kmol) of the compound shown in formula 2 can be 1: (0.1-10), for example, 1:0.2, 1:0.5, 1:0.8, 1:1, 1:2, 1:4, 1:6, 1:8.

[0035] In a specific embodiment, the preparation method comprises: sequentially feeding a solvent, a compound shown in formula 2 and succinic anhydride into a reaction kettle, and stirring at 45-100°C under normal pressure until the HPLC content of the compound shown in formula 2 is less than 1%, which is considered as the end of the reaction, and the preferred reaction temperature is 50-60°C.

[0036] The reaction was considered complete when the content of the compound represented by Formula 2 in the reaction system was confirmed by HPLC control to be less than 1%. The mixture was cooled to below 25°C with stirring and insulated for 1 hour. After the insulated stirring was completed, the reaction system became a white suspension. The material was discharged and centrifuged. The filter cake became a white solid, which was placed in a double-cone dryer and dried at (90-100°C, -0.09 MPa) to obtain the dihalogenophenylsuccinamic acid represented by Formula 3. The main components of the filtrate were the solvent, dihalogenoaniline, succinic anhydride and dihalogenophenylsuccinamic acid, which was used for the next batch of reactions.

[0037] HPLC conditions are as follows:

[0038] Column: Puresil C18

[0039] Column temperature: room temperature

[0040] Wavelength: 246nm

[0041] Mobile phase: methanol: water: phosphoric acid = 54:45:1

[0042] Flow rate: 0.8 mL / min

[0043] Typical dihalogenated phenyl succinamic acid (the exact structure is compound 2: N-(2,4-dichlorophenyl) succinamic acid) appears as a white needle-shaped solid.

[0044] When M is K, the preparation method comprises: reacting a solvent, a compound represented by Formula 3, and a potassium salt to obtain a dihalogenated phenyl succinamic acid metal salt in which M is K, wherein the potassium salt is selected from one or more of potassium carbonate, potassium bicarbonate, and potassium hydroxide.

[0045] When M is Na, the preparation method comprises: reacting a solvent, a compound represented by Formula 3, and a sodium salt to obtain a dihalogenophenyl succinamic acid metal salt in which M is Na, wherein the sodium salt is selected from one or more of sodium carbonate, sodium bicarbonate, and sodium hydroxide.

[0046] In one embodiment, the dihalogenophenyl succinamic acid of Formula 3 obtained in the previous step is added to water or acetonitrile, and the pH is adjusted to 8-9 with potassium carbonate, potassium bicarbonate, or potassium hydroxide at room temperature. The material is centrifuged, and the filter cake is dried to obtain the metal potassium salt of dihalogenophenyl succinamic acid. The filtrate is used for the next batch of reactions. Similarly, the dihalogenophenyl succinamic acid of Formula 3 obtained in the previous step is added to water or acetonitrile, and the pH is adjusted to 8-9 with sodium carbonate, sodium bicarbonate, or sodium hydroxide at room temperature to obtain the metal sodium salt of dihalogenophenyl succinamic acid. The general reaction equation is as follows.

[0047]

[0048] Typical dihalogenated phenyl succinamic acid metal salts (the exact structure is compound 20: sodium N-(2,4-dichlorophenyl) succinamic acid) appear as off-white to white powder.

[0049] In one embodiment,

[0050] When M is H, in the preparation method, the solvent is selected from one or more of benzene, toluene, nitrobenzene, chlorobenzene, fluorinated benzene, mixed xylene, and acetonitrile, preferably, the solvent is mixed xylene; and / or,

[0051] When M is H, in the preparation method, the molar ratio of the compound represented by Formula 2 to succinic anhydride is 1:(1-1.3), preferably, the molar ratio is 1:1.1; and / or,

[0052] When M is H, in the preparation method, the reaction temperature is 45-100° C., the reaction pressure is normal pressure, and the reaction is considered complete when the proportion of the compound represented by Formula 2 in the reaction system in HPLC is less than 1%. Preferably, the reaction temperature is 50-60° C.; and / or,

[0053] When M is H, in the preparation method, after the reaction is completed, dihalogenated phenyl succinamic acid is obtained by centrifugation or filtration, and the filtrate is used for the next batch of reaction; and / or,

[0054] When M is K or Na, in the preparation method, the solvent is selected from one or more of water and acetonitrile; and / or,

[0055] When M is K or Na, in the preparation method, the pH value of the reaction system after mixing is 8-9; and / or,

[0056] When M is K or Na, in the preparation method, after the reaction is completed, the compound shown in Formula 3 is obtained by centrifugation or filtration, and the filtrate is used for the next batch of reaction.

[0057] When M is K or Na and the solvent is selected from water, the ratio of the molar amount (mol) of the solvent to the molar amount (mol) of the compound represented by Formula 3 can be (5-30):1, for example, 8:1, 10:1, 15:1, 18:1, 20:1, 25:1, 28:1.

[0058] When M is K or Na and the solvent is selected from acetonitrile, the ratio of the molar amount (mol) of the solvent to the molar amount (mol) of the compound represented by Formula 3 can be (3-20):1, for example, 5:1, 8:1, 10:1, 15:1, 18:1.

[0059] A compound fertilizer comprises nitrogen fertilizer and any one of the above-mentioned dihalogenophenylsuccinamic acids and metal salts.

[0060] In a specific embodiment, the nitrogen fertilizer is selected from one or more of ammonium nitrogen fertilizer, nitrate nitrogen fertilizer, ammonium nitrate nitrogen fertilizer and amide nitrogen fertilizer.

[0061] In a specific embodiment, the ammonium nitrogen fertilizer is selected from one or more of ammonium sulfate, ammonium chloride, and ammonium bicarbonate; the nitrate nitrogen fertilizer is selected from one or more of sodium nitrate, calcium nitrate, and ammonium nitrate; the ammonium nitrate nitrogen fertilizer is selected from one or more of ammonium nitrate, calcium ammonium nitrate, and ammonium sulfate nitrate; and the amide nitrogen fertilizer is selected from one or more of urea, urea formaldehyde, and butylidene diurea.

[0062] In a specific embodiment, the amount of the dihalogenated phenyl succinamic acid and the metal salt added is 0.2‰-10‰ of the mass of the nitrogen fertilizer;

[0063] Preferably, the addition amount of the dihalogenated phenyl succinamic acid and the metal salt is 0.5‰-5‰ of the mass of the nitrogen fertilizer;

[0064] More preferably, the added amount of the dihalogenated phenyl succinamic acid and the metal salt is 1‰-5‰ of the mass of the nitrogen fertilizer;

[0065] Most preferably, the added amount of the dihalogenated phenylsuccinamic acid and the metal salt is 3‰ of the mass of the nitrogen fertilizer.

[0066] In one embodiment, the compound fertilizer further comprises an auxiliary material, which can be selected from one or more of kaolinite, montmorillonite, illite, and allophane. The auxiliary material is generally added in an amount of 5‰ of the weight of the nitrogen fertilizer, for example, 1-15‰. The compound fertilizer can be obtained by thoroughly mixing the nitrogen fertilizer, dihalogenated phenyl succinamic acid, a metal salt, water, and the auxiliary material, followed by granulation and drying. The amount of water added can be 10%-150% of the weight of the nitrogen fertilizer, for example, 40%, 80%, or 100%.

[0067] The fertilizer compounded with sodium dihalogenophenyl succinate (the exact structure is compound 21: sodium N-(2,5-dichlorophenyl) succinate) and ammonium sulfate appears as light yellow granules.

[0068] The fertilizer compounded with potassium dihalophenyl succinate (the exact structure is compound 43: potassium N-(3,5-difluorophenyl) succinate) and urea has the appearance of light yellow granules.

[0069] A use of dihalogenated phenyl succinamic acid and a metal salt in nitrogen fertilizer synergism, wherein the dihalogenated phenyl succinamic acid or its metal salt has a structure as shown in Formula 1,

[0070] Formula 1:

[0071] Wherein, R1-R6 are each independently selected from H, Cl or F, and only two of R1-R6 are F or Cl at the same time, and M is H, K or Na.

[0072] A method for improving nitrogen fertilizer utilization efficiency, comprising: applying the dihalogenated phenyl succinamic acid and metal salt as described in any one of the above items to land containing nitrogen fertilizer, or compounding nitrogen fertilizer with the dihalogenated phenyl succinamic acid and metal salt as described in any one of the above items and applying the resultant mixture to the land.

[0073] The mechanism of action of dihalogenated phenylsuccinamic acid and metal salts as nitrogen fertilizer synergists is as follows:

[0074] Nitrifying bacteria inhibitors and nitrogen fertilizer synergists affect the electron transfer in the respiration of nitrifying bacteria and interfere with the function of cytochrome oxidase, making it impossible for nitrifying bacteria to respire normally, thereby inhibiting their growth and reproduction (Yuan, X., Li, Y., & Shi, Y. (2024). Synergistic nitrogen fertiliser effects on nitrogen metabolism of wheat in saline-alkaline land. Plant, Soil and Environment, 70(6), 377-393.). The N (nitrogen) atom in the urease inhibitor nitrogen fertilizer synergist molecule can form a ligand with the nickel atom in urease, and the amino compound in the molecule can also form a tridentate ligand with the oxygen atom in the carbamate bridge. This ligand is stronger than the monodentate ligand formed by urea and urease, thereby reducing the contact opportunity between urea and urease and slowing down the hydrolysis process of urea (Qi, Z., Wang, M., Dong, Y., He, M., & Dai, X. (2022). Effect of coated urease / nitrification inhibitor synergistic urea on maize growth and nitrogen use efficiency. Journal of Soil Science and Plant Nutrition, 22 (4), 5207-5216.). The dihalogenated phenyl succinamates and their metal salts involved in the present invention have the effects of both nitrifying bacteria inhibitors and urease inhibitors, and the nitrifying bacteria inhibitory effect is slightly better than the urease inhibitory effect.

[0075] Compared with the prior art, the beneficial effects of the present invention include at least:

[0076] The dihalogenated phenylsuccinamic acid and its potassium (sodium) salt involved in the present invention can be used as nitrogen fertilizer synergists to effectively inhibit the activity of nitrifying bacteria in the soil, reduce the conversion of ammonium nitrogen into nitrate nitrogen, and simultaneously inhibit the decomposition of nitrogen fertilizers such as urea by urease, so that more nitrogen fertilizers can be absorbed and utilized by crops, significantly improving the utilization rate of nitrogen fertilizers, reducing nitrogen losses, and enhancing agricultural production benefits.

[0077] Precisely because of the reduced leaching and volatilization of nitrogen fertilizer, the nitrogen fertilizer synergist involved in the present invention reduces the risk of nitrogen pollution to the surrounding environment, including reducing nitrate pollution in groundwater and reducing ammonia emissions, which is beneficial to protecting the ecological environment and meets the requirements of sustainable agricultural development.

[0078] The potassium (sodium) dihalogenophenyl succinamate salt disclosed by the present invention has good water solubility, is easy to be compounded with nitrogen fertilizer and then applied, exhibits good chemical stability and physical stability during use, is not easily affected by external environmental factors and decomposed or rendered ineffective, ensures the use effect under various soil conditions and climatic conditions, and provides reliable protection for agricultural production.

[0079] In addition, the preparation process of the potassium (sodium) dihalogenophenyl succinamate salt of the present invention is safe and controllable, simple to operate, the centrifuged mother liquor can be recycled, no wastewater or waste residue is generated, the total yield is high, the purity of the final product obtained is higher than 99.5%, and the main raw materials are cheap and easily available, so that the cost of the final product is controllable, which is conducive to large-scale promotion in agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 It is the HPLC spectrum of compound 1 in Example 1 of the present invention.

[0081] Figure 2 It is the HPLC spectrum of compound 1 in Example 2 of the present invention.

[0082] Figure 3 It is the HPLC spectrum of compound 1 in Example 3 of the present invention.

[0083] Figure 4 It is the HPLC spectrum of compound 3 in Example 5 of the present invention. DETAILED DESCRIPTION

[0084] Example embodiments will now be described more fully. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art.

[0085] All raw materials are commercially available industrial grade, and the purity is required to be higher than 99%.

[0086] The compound disclosed by the present invention (including its salt) can be prepared using known organic synthesis techniques and can be synthesized according to any approach in numerous possible synthetic pathways, and if compound (including its salt) is a known compound, it can be obtained commercially. The reaction for preparing the compound disclosed by the present invention can be carried out in a suitable solvent that can be easily selected by those skilled in the art of organic synthesis. Suitable solvents can be substantially not reacted with starting material, intermediate or product under the temperature (for example, ranging from room temperature to the boiling temperature of solvent) of reacting. Given reaction can be carried out in a mixture of a solvent or a plurality of solvents.

[0087] (1) Preparation of dihalogenated phenyl succinamic acid and its metal salts

[0088] Example 1

[0089] Preparation of 2,3-dichlorophenylsuccinamic acid (Compound 1)

[0090]

[0091] Toluene (4000.00 kg), 2,3-dichloroaniline (1250.00 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred, heated to 100-105°C and stirred at this temperature for 5 hours.

[0092] After the insulation reaction is completed, the reaction system is a white suspension. Samples are taken for HPLC control. After confirming that the residual amount of 2,3-dichloroaniline is less than 1%, the mixture is stirred and cooled to below 25°C and kept warm and stirred for 1 hour. After the insulation and stirring are completed, the material is discharged and centrifuged. The filter cake is a white needle-shaped solid (the filtrate is used for the next batch), with a wet weight of 1823.21 kg. It is placed in a double cone dryer and dried under (90-100°C, -0.09MPa) conditions to obtain 1678.21 kg of 2,3-dichlorophenyl succinamide acid finished product with a molar yield of 82.99%. It is a white needle-shaped solid with an HPLC purity of 99.68%. The HPLC spectrum is as follows Figure 1 shown.

[0093] 1 H NMR (400MHz, DMSO-d6) δ12.18(s,1H), δ8.50(s,1H), δ7.66(d,J=8.5Hz,1H), δ7.55(dd,1H), δ7.40(d,J=2.0Hz,1H), δ3.35(t,2H), δ2.65(t,2H).

[0094] Example 2

[0095] Preparation of 2,3-dichlorophenylsuccinamic acid (Compound 1)

[0096]

[0097] Toluene (4000.00 kg), 2,3-dichloroaniline (1250.00 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, heated to 55-60°C with stirring and kept stirring at this temperature for 5 hours.

[0098] After the insulation reaction is completed, the reaction system is a white suspension. Samples are taken for HPLC control. After confirming that the residual amount of 2,3-dichloroaniline is less than 1%, the mixture is stirred and cooled to below 25°C and kept warm and stirred for 1 hour. After the insulation and stirring are completed, the material is discharged and centrifuged. The filter cake is a white needle-shaped solid (the filtrate is used for the next batch), with a wet weight of 1908.33 kg. It is placed in a double cone dryer and dried under (90-100°C, -0.09 MPa) conditions to obtain 1706.08 kg of finished 2,3-dichlorophenyl succinamide acid, with a molar yield of 84.37%, a white needle-shaped solid, and an HPLC purity of 99.72%. The HPLC spectrum is as follows Figure 2 shown.

[0099] Example 3

[0100] Preparation of 2,3-dichlorophenylsuccinamic acid (Compound 1)

[0101]

[0102] Mixed xylene (4000.00 kg), 2,3-dichloroaniline (1250.00 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred and heated to 55-60°C and kept stirring at this temperature for 5 hours.

[0103] After the insulation reaction is completed, the reaction system is a white suspension. Samples are taken for HPLC control. After confirming that the residual amount of 2,3-dichloroaniline is less than 1%, the mixture is stirred and cooled to below 25°C and kept warm and stirred for 1 hour. After the insulation and stirring are completed, the material is discharged and centrifuged. The filter cake is a white needle-shaped solid (the filtrate is used for the next batch), with a wet weight of 2038.28 kg. It is placed in a double cone dryer and dried under (90-100°C, -0.09 MPa) conditions to obtain 1825.66 kg of finished 2,3-dichlorophenyl succinamide acid, with a molar yield of 90.28%, a white needle-shaped solid, and an HPLC purity of 99.68%. The HPLC spectrum is as follows Figure 3 shown.

[0104] Example 4

[0105] Preparation of 2,4-dichlorophenylsuccinamic acid (Compound 2)

[0106]

[0107] Mixed xylene (4000.00 kg), 2,4-dichloroaniline (1250.00 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred, heated to 80-85°C and kept stirring at this temperature for 5 hours.

[0108] After the incubation period, the reaction system presented a white suspension. Samples were taken for HPLC control. After confirming that the residual 2,4-dichloroaniline was less than 1%, the mixture was stirred and cooled to below 25°C, where it was incubated and stirred for 1 hour. After the incubation period, the mixture was discharged and centrifuged. The filter cake, with a wet weight of 1805.22 kg, was a white needle-shaped solid (the filtrate was used for the next batch). The cake was dried in a double-cone dryer at 90-100°C, -0.09 MPa, to yield 1625.38 kg of finished 2,4-dichlorophenylsuccinamic acid, a white needle-shaped solid with a molar yield of 80.38% and an HPLC purity of 99.82%.

[0109] 1 H NMR (400MHz, DMSO-d6) δ12.08 (s, 1H), δ8.35 (s, 1H), δ7.65 (d, J = 8.5Hz, 1H), δ7.49 (dd, J1=8.5Hz, J2=2.0Hz, 1H), δ7.38 (d, J=2.0Hz, 1H), δ2.51 (t, 2H), δ2.49 (t, 2H).

[0110] Example 5

[0111] Preparation of 2,5-dichlorophenylsuccinamic acid (Compound 3)

[0112]

[0113] Mixed xylene (4000.00 kg), 2,5-dichloroaniline (1250.00 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred, heated to 55-60°C and kept stirred at this temperature for 5 hours.

[0114] After the insulation reaction is completed, the reaction system is a white suspension. Samples are taken for HPLC control. After confirming that the residual amount of 2,5-dichloroaniline is less than 1%, the mixture is stirred and cooled to below 25°C and kept warm and stirred for 1 hour. After the insulation and stirring are completed, the material is discharged and centrifuged. The filter cake is a white needle-shaped solid (the filtrate is used for the next batch), with a wet weight of 2025.11 kg. It is placed in a double cone dryer and dried under (90-100°C, -0.09MPa) conditions to obtain 1830.59 kg of finished 2,5-dichlorophenyl succinamide acid, with a molar yield of 90.53%, a white needle-shaped solid, and an HPLC purity of 99.92%. The HPLC spectrum is as follows Figure 4 shown.

[0115] 1 H NMR (400MHz, DMSO-d6) δ12.10 (s, 1H), δ10.20 (s, 1H), δ7.62 (d, J = 8.2Hz, 1H), δ7.51 (dd, J1=8.4Hz, J2=2.1Hz, 1H), δ7.35 (d, J=2.0Hz, 1H), δ2.57 (t, 2H), δ2.44 (t, 2H).

[0116] Example 6

[0117] Preparation of 2,5-dichlorophenylsuccinamic acid (Compound 3)

[0118]

[0119] The centrifuged mother liquor in Example 5, 2,5-dichloroaniline (1250.00 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred, heated to 55-60°C and kept stirred at this temperature for 5 h.

[0120] After the incubation period, the reaction system presented a white suspension. Samples were taken for HPLC control to confirm that the residual 2,5-dichloroaniline was less than 1%. The mixture was then stirred and cooled to below 25°C, incubated with stirring for 1 hour. After the incubation period, the mixture was centrifuged to yield a filter cake of white needle-shaped solids (the filtrate was used for the next batch). The filter cake had a wet weight of 2086.93 kg. The cake was dried in a double-cone dryer at 90-100°C, -0.09 MPa, to yield 1907.34 kg of finished 2,5-dichlorophenylsuccinamic acid as a white needle-shaped solid with a molar yield of 94.32% and an HPLC purity of 99.91%.

[0121] Example 7

[0122] Preparation of 2,6-dichlorophenylsuccinamic acid (Compound 4)

[0123]

[0124] Mixed xylene (4000.00 kg), 2,6-dichloroaniline (1250.00 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred, heated to 55-60°C and kept stirred at this temperature for 5 hours.

[0125] After the incubation period, the reaction system presented a white suspension. Samples were taken for HPLC control to confirm that the residual 2,6-dichloroaniline was less than 1%. The mixture was then stirred and cooled to below 25°C, incubated with stirring for 1 hour. After the incubation period, the mixture was centrifuged to yield a filter cake of 1998.67 kg of white needle-shaped solids (the filtrate was used for the next batch). The filter cake was dried in a double-cone dryer at 90-100°C, -0.09 MPa, to yield 1778.22 kg of 2,6-dichlorophenylsuccinamic acid as a white needle-shaped solid with a molar yield of 87.94% and an HPLC purity of 99.89%.

[0126] 1 H NMR (400MHz, DMSO-d6) δ11.95 (s, 1H), δ9.92 (s, 1H), δ7.62 (d, J = 8.5Hz, 1H), δ7.48 (d, J1 = 8. 5Hz, J2=2.0Hz, 1H), δ7.33 (d, J=2.0Hz, 1H), δ2.55 (t, J=7.0Hz, 2H), δ2.41 (t, J=7.0Hz, 2H).

[0127] Example 8

[0128] Preparation of 3,5-dichlorophenylsuccinamic acid (Compound 7)

[0129]

[0130] Mixed xylene (4000.00 kg), 3,5-dichloroaniline (1250.00 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred, heated to 55-60°C and kept stirred at this temperature for 5 hours.

[0131] After the incubation period, the reaction system presented a white suspension. Samples were taken for HPLC control to confirm that the residual 3,5-dichloroaniline was less than 1%. The mixture was then stirred and cooled to below 25°C, incubated with stirring for 1 hour. After the incubation period, the mixture was centrifuged to yield a filter cake of 2012.30 kg of white needle-shaped solids (the filtrate was used for the next batch). The filter cake was dried in a double-cone dryer at 90-100°C, -0.09 MPa, to yield 1851.04 kg of finished 3,5-dichlorophenylsuccinamic acid, a white needle-shaped solid with a molar yield of 91.54% and an HPLC purity of 99.89%.

[0132] 1 H NMR (400MHz, DMSO-d6) δ11.98(s,1H), δ10.22(s,1H), δ7.67(s,1H), δ7.49(s,1H), δ7.38(s,1H), δ2.58(t,2H), δ2.46(t,2H).

[0133] Example 9

[0134] Preparation of 2,3-difluorophenylsuccinamic acid (Compound 28)

[0135]

[0136] Mixed xylene (3500.00 kg), 2,3-difluoroaniline (996.73 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred and heated to 55-60°C and kept stirring at this temperature for 5 hours.

[0137] After the incubation period, the reaction system presented a white suspension. Samples were taken for HPLC control. After confirming that the residual 2,3-difluoroaniline was less than 1%, the mixture was stirred and cooled to below 25°C, incubated and stirred for 1 hour. After the incubation period, the mixture was discharged and centrifuged. The filter cake, with a wet weight of 1622.81 kg, was obtained as a white needle-shaped solid (the filtrate was used for the next batch). The filter cake was dried in a double-cone dryer at (90-100°C, -0.09 MPa) to yield 1530.02 kg of finished 2,3-difluorophenylsuccinamic acid, a molar yield of 86.49%, as a white needle-shaped solid with an HPLC purity of 99.76%.

[0138] 1H NMR (400MHz, DMSO-d6) δ12.25(s,1H), δ8.82(s,1H), δ7.73(d,J=8.5Hz,1H), δ7.58(dd,1H), δ7.42(d,J=2.0Hz,1H), δ3.25(t,2H), δ2.63(t,2H).

[0139] Example 10

[0140] Preparation of 3,5-difluorophenylsuccinamic acid (Compound 34)

[0141]

[0142] Mixed xylene (4000.00 kg), 3,5-difluoroaniline (996.73 kg, 7.72 kmol) and succinic anhydride (850.00 kg, 8.49 kmol) were sequentially added into an 8000 L glass-lined reactor equipped with a condenser, stirred and heated to 55-60°C and kept stirring at this temperature for 5 hours.

[0143] After the incubation period, the reaction system presented a white suspension. Samples were taken for HPLC control. After confirming that the residual 3,5-difluoroaniline was less than 1%, the mixture was stirred and cooled to below 25°C, incubated and stirred for 1 hour. After the incubation period, the mixture was discharged and centrifuged. The filter cake, with a wet weight of 1642.55 kg, was a white needle-shaped solid (the filtrate was used for the next batch). The filter cake was dried in a double-cone dryer at (90-100°C, -0.09 MPa) to yield 1551.56 kg of finished 3,5-difluorophenylsuccinamic acid, a molar yield of 87.69%, as a white needle-shaped solid with an HPLC purity of 99.94%.

[0144] 1 H NMR (400MHz, DMSO-d6) δ12.14(s,1H), δ10.05(s,1H), δ7.63(s,1H), δ7.53(s,1H), δ7.25(s,1H), δ2.60(t,2H), δ2.51(t,2H).

[0145] Example 11

[0146] Preparation of Sodium 2,5-Dichlorophenylsuccinamate (Compound 21)

[0147]

[0148] Water (1800.00 kg, 100.00 kmol) and 2,5-dichlorophenylsuccinamic acid (1500.00 kg, 5.72 kmol) were sequentially added into a 5000 L glass-lined reactor and stirred evenly to obtain a viscous white slurry reaction liquid. The temperature was controlled not to exceed 30°C and 30% sodium hydroxide (785.00 kg, 5.89 kmol) was added into the reactor.

[0149] After the addition of 30% sodium hydroxide, the reaction system became slightly thinner than the initial state, forming a white suspension. Visual inspection of the sample revealed the disappearance of the white needle-like crystals. The pH was measured, and after confirming that the pH was 8-9, the mixture was stirred for 3 hours. After stirring, the mixture was centrifuged to produce a filter cake of white powder (the filtrate was used for the next batch). The filter cake had a wet weight of 1512.70 kg. The cake was dried in a double-cone dryer at (90-100°C, -0.09 MPa) to obtain 1467.51 kg of finished sodium 2,5-dichlorophenyl succinamate, a molar yield of 90.26%, and a white powder with an HPLC purity of 99.94%.

[0150] 1 H NMR (400MHz, DMSO-d6) δ10.22 (s, 1H), δ7.63 (d, J = 8.2Hz, 1H), δ7.55 (dd, J1 = 8.5Hz, J2 = 2.0Hz, 1H), δ7.32 (d, J = 2.0Hz, 1H), δ2.53 (t, 2H), δ2.49 (t, 2H).

[0151] Example 12

[0152] Preparation of Sodium 2,5-Dichlorophenylsuccinamate (Compound 21)

[0153]

[0154] Acetonitrile (1600.00 kg, 38.97 kmol) and 2,5-dichlorophenylsuccinamic acid (1500.00 kg, 5.72 kmol) were sequentially added into a 5000 L glass-lined reactor and stirred evenly to obtain a white suspension. The temperature was controlled not to exceed 30°C and 30% sodium hydroxide (785.00 kg, 5.89 kmol) was added into the reactor.

[0155] After the addition of 30% sodium hydroxide, the reaction system became slightly more viscous than the initial state, forming a white suspension. Visual inspection of the sample revealed the disappearance of the white needle-like crystals. The pH was measured, and after confirming that the pH was 8-9, the mixture was stirred for 3 hours. After stirring, the mixture was centrifuged to produce a filter cake of white powder (the filtrate was used for the next batch) with a wet weight of 1433.89 kg. The cake was dried in a double-cone dryer at (90-100°C, -0.09 MPa) to obtain 1355.15 kg of finished sodium 2,5-dichlorophenyl succinamate, with a molar yield of 83.35%. The product was a white powder with an HPLC purity of 99.98%.

[0156] Example 13

[0157] Preparation of Potassium 2,5-Dichlorophenylsuccinamate (Compound 12)

[0158]

[0159] Water (2000.00 kg) and 2,5-dichlorophenylsuccinamic acid (1500.00 kg, 5.72 kmol) were sequentially added into a 5000 L glass-lined reactor and stirred evenly to obtain a viscous white slurry reaction liquid. The temperature was controlled not to exceed 30°C and 45% potassium hydroxide (735.00 kg, 5.89 kmol) was added into the reactor.

[0160] After the addition of 45% potassium hydroxide, the reaction system became slightly thinner than the initial state, forming a white suspension. Visual inspection of the sample revealed the disappearance of the white needle-like crystals. The pH was measured to confirm that the pH was 8-9, and then the mixture was stirred for 3 hours. After the stirring was completed, the mixture was centrifuged to produce a filter cake of white powder (the filtrate was used for the next batch). The filter cake had a wet weight of 1623.35 kg. The filter cake was dried in a double-cone dryer at (90-100°C, -0.09 MPa) to obtain 1478.86 kg of finished potassium 2,5-dichlorophenyl succinamate, a molar yield of 86.08%, and a white powder with an HPLC purity of 99.81%.

[0161] 1 H NMR (400MHz, DMSO-d6) δ11.03 (s, 1H), δ7.78 (d, J = 8.2Hz, 1H), δ7.58 (dd, J1 = 8.6Hz, J2 = 2.2Hz, 1H), δ7.43 (d, J = 2.0Hz, 1H), δ2.51 (t, 2H), δ2.46 (t, 2H).

[0162] Example 14

[0163] Preparation of Potassium 3,5-Dichlorophenylsuccinamate (Compound 16)

[0164]

[0165] Water (2000.00 kg) and 3,5-dichlorophenylsuccinamic acid (1500.00 kg, 5.72 kmol) were sequentially added into a 5000 L glass-lined reactor and stirred evenly to obtain a viscous white slurry reaction liquid. The temperature was controlled not to exceed 30°C and 45% potassium hydroxide (735.00 kg, 5.89 kmol) was added into the reactor.

[0166] After the addition of 45% potassium hydroxide, the reaction system became slightly thinner than the initial state, forming a white suspension. Visual inspection of the sample revealed the disappearance of the white needle-like crystals. The pH was measured, and after confirming that the pH was 8-9, the mixture was stirred for 3 hours. After stirring, the mixture was centrifuged to produce a filter cake of white powder (the filtrate was used for the next batch). The filter cake had a wet weight of 1651.83 kg. The filter cake was dried in a double-cone dryer at (90-100°C, -0.09 MPa) to obtain 1491.44 kg of finished potassium 3,5-dichlorophenyl succinamate, a molar yield of 86.81%, and a white powder with an HPLC purity of 99.79%.

[0167] 1 H NMR (400MHz, DMSO-d6) δ10.13(s,1H), δ7.61(s,1H), δ7.58(s,1H), δ7.33(s,1H), δ2.66(t,2H), δ2.54(t,2H).

[0168] Example 15

[0169] Preparation of sodium 3,5-dichlorophenylsuccinamate (Compound 25)

[0170]

[0171] Water (1800.00 kg, 100.00 kmol) and 3,5-dichlorophenylsuccinamic acid (1500.00 kg, 5.72 kmol) were sequentially added into a 5000 L glass-lined reactor and stirred evenly to obtain a viscous white slurry reaction liquid. The temperature was controlled not to exceed 30°C and 30% sodium hydroxide (785.00 kg, 5.89 kmol) was added into the reactor.

[0172] After adding 30% sodium hydroxide, the reaction system becomes slightly thinner than the initial state, and is a white suspension. Visually, the white needle-shaped crystals can be obviously found to disappear. After confirming that the pH is 8-9, continue to heat and stir for 3 h. After heating and stirring, the discharge is centrifuged, and the filter cake is a white powder solid (the filtrate is used for the next batch). The wet weight is 1535.01 kg, which is placed in a double-cone dryer under the condition of (90-100 ℃, -0.09 MPa) to dry, and 3,5-dichlorophenyl succinamate sodium product 1411.76 kg is obtained, with a molar yield of 86.84%, which is a white powder solid, and the HPLC purity is 99.85%.

[0173] 1 H NMR (400 MHz, DMSO-d6) δ 10.22 (s, 1H), δ 7.68 (s, 1H), δ 7.55 (s, 1H), δ 7.41 (s, 1H), δ 2.59 (t, 2H), δ 2.52 (t, 2H).

[0174] Example 16

[0175] Preparation of 3,5-difluorophenyl succinamate sodium (compound 52)

[0176]

[0177] Water (1800.00 kg, 100.00 kmol) and 3,5-difluorophenyl succinamate (1500.00 kg, 6.55 kmol) were sequentially added into a 5000 L glass-lined reaction kettle, and stirred to obtain a viscous white slurry. The temperature was controlled not to exceed 30 ℃, and 30% sodium hydroxide (925.00 kg, 6.94 kmol) was added into the reaction kettle.

[0178] After adding 30% sodium hydroxide, the reaction system becomes slightly thinner than the initial state, and is a white suspension. Visually, the white needle-shaped crystals can be obviously found to disappear. After confirming that the pH is 8-9, continue to heat and stir for 3 h. After heating and stirring, the discharge is centrifuged, and the filter cake is a white powder solid (the filtrate is used for the next batch). The wet weight is 1535.01 kg, which is placed in a double-cone dryer under the condition of (90-100 ℃, -0.09 MPa) to dry, and 3,5-dichlorophenyl succinamate sodium product 1411.76 kg is obtained, with a molar yield of 86.84%, which is a white powder solid, and the HPLC purity is 99.85%.

[0179] 1H NMR (400MHz, DMSO-d6) δ10.50(s,1H), δ7.65(s,1H), δ7.51(s,1H), δ7.44(s,1H), δ2.58(t,2H), δ2.49(t,2H).

[0180] (2) Preparation and effect verification of nitrogen fertilizer compounds

[0181] 1. Weigh a certain amount of nitrogen fertilizer (urea and ammonium sulfate) and the dihalogenated phenylsuccinamic acid or its metal salt nitrogen fertilizer synergist involved in the present invention (the addition amount is 0.3% by mass of the nitrogen fertilizer) and place them in a mixing container. Add appropriate amount of water and auxiliary materials, mix thoroughly, granulate and dry to obtain a series of nitrogen fertilizer compounds. The nitrogen fertilizer compounds are marked with nitrogen fertilizer synergist serial numbers Compound 1 to Compound 54 for distinction.

[0182] The auxiliary material can be selected from one or more of kaolinite, montmorillonite, illite, and allophane. The amount of water added is 10%-150% of the mass of the nitrogen fertilizer, and the amount of the auxiliary material added is 1‰-15‰ of the mass of the nitrogen fertilizer. In this embodiment, the auxiliary material is 300 mesh kaolinite powder, the amount of water added is 50% of the mass of the nitrogen fertilizer, and the amount of the auxiliary material added is 5‰ of the mass of the nitrogen fertilizer.

[0183] 2. Take two equal amounts of cultivated soil from Shilin Town, Dengzhou City, Nanyang City, Henan Province (soil A), Yeshan Town, Tianchang City, Anhui Province (soil B), Qinghemen District, Fuxin City, Liaoning Province (soil C), Zhoupu Town, Pudong New Area, Shanghai (soil D), and Dalubian Town, Lianzhou City, Qingyuan City, Guangdong Province (soil E), a total of 5 areas, and place them in containers. One of the soils was added with the nitrogen fertilizer compound prepared in the previous step and mixed evenly as the test group (the addition amount was 5% of the soil mass), and the other was added with nitrogen fertilizer without nitrogen fertilizer synergist and mixed evenly as the blank group. A total of 54*5=270 test groups (each test group was tested with two types of fertilizers, urea and ammonium sulfate) and 54*5=270 controls (each blank group was tested with two types of fertilizers, urea and ammonium sulfate). The test groups and blank groups were divided into two parts, one for testing the initial value of the fertilizer content, and the other for measuring the fertilizer content in the soil after standing at room temperature for 30 days. To determine fertilizer content, add water equal in mass to the soil mass and stir at room temperature for the same amount of time (2 hours, until no fertilizer particles are visible to the naked eye). Then, remove the soil by filtration. Add water to the filtrate or concentrate it to the same total weight as the fertilizer and soil mass. Determine the fertilizer content using conventional analytical chemistry methods. See Table 2 for test data on nitrogen fertilizer synergists.

[0184] Table 2 Nitrogen fertilizer synergist test data

[0185]

[0186]

[0187]

[0188]

[0189]

[0190]

[0191]

[0192]

[0193]

[0194]

[0195]

[0196]

[0197]

[0198]

[0199] According to the test data results of Table 2, compounds 3, 12, 21, 28, 31, 37, 40, 46 and 49 exhibit significant nitrogen fertilizer synergistic effect, specifically, in the case of not being affected by crop absorption, these compounds can effectively reduce the natural loss rate of nitrogen fertilizer. For detailed compound structure information, please refer to the data listed in Table 3.

[0200] Table 3 List of compounds with significant nitrogen fertilizer synergistic effect

[0201]

[0202]

[0203] Moisture absorption tests were performed on compounds 3, 12, 21, 28, 31, 37, 40, 46 and 49. The specific test method was to weigh the same amount of compounds 3, 12, 21, 28, 31, 37, 40, 46, 49, ammonium sulfate (powder, ungranulated), urea (powder, ungranulated), compound 3, 12, 21, 28, 31, 37, 40, 46 and 49 mixed with 99.7% ammonium sulfate powder (thoroughly mixed), and compound 3, 12, 21, 28, 31, 37, 40, 46 and 49 mixed with 99.7% urea powder (thoroughly mixed), and then placed in an open petri dish at room temperature for 10 days, and then weighed again. The test results are shown in Table 4.

[0204] Table 4 Hygroscopicity test results

[0205]

[0206]

[0207] The change in water solubility of dihalogenophenyl succinamic acid after it was converted into Na (sodium) salt or K (potassium) salt was investigated. The specific investigation method was to weigh the same weight of dihalogenophenyl succinamic acid and the corresponding Na (sodium) salt / K (potassium) salt, add the same weight of water, stir at room temperature for the same time, filter, and dry the filter cake. The weight of the solid lost is the weight dissolved by water, and the water solubility is calculated based on this. The results of the water solubility investigation are shown in Table 5.

[0208] Table 5 Water solubility investigation results

[0209]

[0210]

[0211] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limiting the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the invention without departing from the principles and purpose of the present invention. All such changes shall fall within the scope of protection of the claims of the present invention.

Claims

1. A dihalogenated phenyl succinamic acid and a metal salt for use as a nitrogen fertilizer synergist, characterized in that: The dihalogenated phenyl succinamic acid and the metal salt have a structure as shown in Formula 1, Formula 1: Wherein, R1-R6 are each independently selected from H, Cl or F, and only two of R1-R6 are F or Cl at the same time, and M is H, K or Na.

2. The dihalogenophenyl succinamic acid and metal salt according to claim 1, wherein The dihalogenated phenyl succinamic acid and the metal salt are selected from compound 3, compound 12, compound 21, compound 28, compound 31, compound 37, compound 40, compound 46 or compound 49; 3. A method for preparing dihalogenophenyl succinamic acid and metal salt according to any one of claims 1 to 2, characterized in that: When M is H, the preparation method comprises: mixing a solvent, a compound represented by Formula 2, and succinic anhydride, and reacting the mixture to obtain a compound represented by Formula 3; When M is K, the preparation method comprises: reacting a solvent, a compound represented by Formula 3, and a potassium salt to obtain a dihalogenated phenyl succinamic acid metal salt in which M is K, wherein the potassium salt is selected from one or more of potassium carbonate, potassium bicarbonate, and potassium hydroxide; When M is Na, the preparation method comprises: reacting a solvent, a compound represented by Formula 3, and a sodium salt to obtain a dihalogenophenyl succinamic acid metal salt in which M is Na, wherein the sodium salt is selected from one or more of sodium carbonate, sodium bicarbonate, and sodium hydroxide.

4. The method for preparing dihalogenophenyl succinamic acid and metal salt according to claim 3, wherein: When M is H, in the preparation method, the solvent is selected from one or more of benzene, toluene, nitrobenzene, chlorobenzene, fluorinated benzene, mixed xylene, and acetonitrile, preferably, the solvent is mixed xylene; and / or, When M is H, in the preparation method, the molar ratio of the compound represented by Formula 2 to succinic anhydride is 1:(1-1.3), preferably, the molar ratio is 1:1.1; and / or, When M is H, in the preparation method, the reaction temperature is 45-100° C., the reaction pressure is normal pressure, and the reaction is considered complete when the proportion of the compound represented by Formula 2 in the reaction system in HPLC is less than 1%. Preferably, the reaction temperature is 50-60° C.; and / or, When M is H, in the preparation method, after the reaction is completed, dihalogenated phenyl succinamic acid is obtained by centrifugation or filtration, and the filtrate is used for the next batch of reaction; and / or, When M is K or Na, in the preparation method, the solvent is selected from one or more of water and acetonitrile; and / or, When M is K or Na, in the preparation method, the pH value of the reaction system after mixing is 8-9; and / or, When M is K or Na, in the preparation method, after the reaction is completed, the compound shown in Formula 3 is obtained by centrifugation or filtration, and the filtrate is used for the next batch of reaction.

5. A compound fertilizer, characterized in that: The method comprises nitrogen fertilizer and the dihalogenophenyl succinamic acid and metal salt as claimed in any one of claims 1 to 2.

6. The compound fertilizer according to claim 5, characterized in that The nitrogen fertilizer is selected from one or more of ammonium nitrogen fertilizer, nitrate nitrogen fertilizer, ammonium nitrate nitrogen fertilizer and amide nitrogen fertilizer.

7. The compound fertilizer according to claim 6, characterized in that The ammonium nitrogen fertilizer is selected from one or more of ammonium sulfate, ammonium chloride, and ammonium bicarbonate; the nitrate nitrogen fertilizer is selected from one or more of sodium nitrate, calcium nitrate, and ammonium nitrate; the ammonium nitrate nitrogen fertilizer is selected from one or more of ammonium nitrate, calcium ammonium nitrate, and ammonium sulfate nitrate; and the amide nitrogen fertilizer is selected from one or more of urea, urea formaldehyde, and butylidene diurea.

8. The compound fertilizer according to any one of claims 5 to 7, characterized in that: The amount of the dihalogenated phenyl succinamic acid and the metal salt added is 0.2‰-10‰ of the mass of the nitrogen fertilizer; Preferably, the addition amount of the dihalogenated phenyl succinamic acid and the metal salt is 0.5‰-5‰ of the mass of the nitrogen fertilizer; More preferably, the added amount of the dihalogenated phenyl succinamic acid and the metal salt is 1‰-5‰ of the mass of the nitrogen fertilizer; Most preferably, the added amount of the dihalogenated phenylsuccinamic acid and the metal salt is 3‰ of the mass of the nitrogen fertilizer.

9. Application of dihalogenated phenyl succinamic acid and metal salt in nitrogen fertilizer synergism, characterized in that: The dihalogenated phenyl succinamic acid and the metal salt have a structure as shown in Formula 1, Formula 1: Wherein, R1-R6 are each independently selected from H, Cl or F, and only two of R1-R6 are F or Cl at the same time, and M is H, K or Na.

10. A method for improving nitrogen fertilizer utilization efficiency, characterized in that: include: The dihalogenophenyl succinamic acid and the metal salt as claimed in any one of claims 1 to 2 are applied to land containing nitrogen fertilizer, or nitrogen fertilizer and the dihalogenophenyl succinamic acid and the metal salt as claimed in any one of claims 1 to 2 are compounded and applied to the land.

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