Nitrification inhibitor for stabilizing fertilizer

Abstract

The invention discloses a nitrification inhibitor for stabilizing a fertilizer, and belongs to the field of agricultural chemistry. The general formula of the nitration inhibitor is # imgabs0, and the nitration inhibitor is relatively simple to prepare and is prepared by reacting diketone with substituted hydrazine or reacting a pyrazole compound with different electrophilic reagents. The nitrification inhibitor disclosed by the invention has relatively good nitrification inhibition activity in agriculture, and has relatively multiple benefits of reducing nitrogen oxides, improving the utilization rate of nitrogen fertilizer, improving the yield and quality of crops and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of agrochemistry, and more specifically relates to nitrification inhibitors, compositions and their applications in the agricultural field.

[0002] Research Background

[0003] Nitrogen is an essential mineral nutrient element for crop growth, and the use of nitrogen fertilizers is of great significance for ensuring stable food production. Nitrification in the soil can rapidly convert ammonium nitrogen (NH4 + )(directly applied or indirectly obtained from nitrogen fertilizers) into nitrite ions (NO2 - ), and is further oxidized into nitrate ions (NO3 - ) which are extremely easy to be leached and cause the risk of groundwater pollution. The entire oxidation process is also accompanied by the release of nitrogen oxides (N eq O), and nitrous oxide (N2O) as a potent greenhouse gas not only accelerates climate change but also damages the ozone layer, and has become one of the important sources of agricultural non-point source pollution.

[0004] The use of nitrification inhibitors can effectively improve fertilizer utilization efficiency. Its main principle lies in inhibiting soil nitrifying microorganisms, delaying the oxidation process of ammonium nitrogen (NH4 + ), improving the nutrient absorption and utilization efficiency of crops, and increasing nitrogen use efficiency. At the same time, it can help reduce nitrogen oxide emissions and nitrate leaching, and reduce the impact of agricultural production on the environment. The Intergovernmental Panel on Climate Change (IPCC) also recommends the use of nitrification inhibitors in agricultural production to mitigate nitrous oxide (N2O) emissions. Currently, the main commercially available nitrification inhibitor products include 3,4-dimethylpyrazole phosphate (DMPP), dicyandiamide (DCD) and 2-chloro-6-trichloromethylpyridine (CP). Among them, DMPP is considered the most promising nitrification inhibitor and has received wide attention due to its good safety, agronomic effects and environmental protection effects. However, overall, the design and development of new nitrification inhibitors lags behind. It is worth noting that recently, the University of Melbourne in Australia reported a series of triazole-based nitrification inhibitors, which showed good nitrification inhibition activity. However, the product synthesis method requires the use of raw materials such as explosives precursors or special process conditions such as microwave reactions, which limits their commercialization prospects (Nature, 2021, 11, 14980; ACS Agric. Sci. Technol. 2023, 3, 867; ACS Agric. Sci. Technol. 2024, 4, 255). However, the current nitrification inhibitors still have problems such as activity, half-life, stability, actual effect differences, ecotoxicology, etc. At the same time, agricultural production is also comprehensively affected by many factors such as region, soil, climate, fertilization method, season, crop type, etc. Therefore, the design and development of new inhibitors still have practical value and research significance. Summary of the Invention

[0005] The present invention mainly aims at the deficiencies of existing nitrification inhibitors, designs and develops a series of novel nitrification inhibitors for reducing nitrification in soil, and provides a synthesis method thereof.

[0006] The nitrification inhibitors of the present invention include: Compound A, Compound B, and the salt forms of Compound A or Compound B. Among them: Compound A is a single compound or a mixture composed of 3,4- and 4,5-isomers on the pyrazole ring; Compound B is a single compound or a mixture composed of 3,4- and 4,5-isomers on the pyrazole ring. The general formula structure of the nitrification inhibitor is:

[0007]

[0008] Wherein: R 1 and R 2 each independently selected from hydrogen or C1-C6 alkyl; R is selected from C2-C6 alkanoyl, benzoyl, succinic acid-2-yl, aminothiocarbonyl, aminocarbonyl, substituted benzenesulfonyl, substituted phenyl, pyridyl, succinimide-2-yl, substituted phenylacetic acid-1-(C1-C4)alkyl, succinic acid-2-(C1-C4)alkyl, 2-ureaacetic acid-1-yl, succinic acid (C1-C4)alkyl ester-2-(C1-C4)alkyl, carboxyl-substituted (C1-C4) straight-chain or branched alkyl, acyl-substituted C1-C4 alkyl; wherein the substituents in the substituted benzenesulfonyl, substituted phenyl, and substituted phenylacetic acid-1-(C1-C4)alkyl are each selected from hydrogen, C1-C4 alkoxycarbonyl, halogen, or C1-C4 alkyl, and the acyl substitution is selected from acetyl or benzoyl; X is selected from phthaloyl, oxalyl, urea N,N'-di(C1-C4)alkyl, diphenylmethanediamine diacyl, C1-C6 alkylenediamine diacyl.

[0009] Further, in the above technical solution, R 1 and R 2 each independently selected from hydrogen or methyl; R is selected from acetyl, benzoyl, succinic acid-2-yl, aminothiocarbonyl, aminocarbonyl, p-toluenesulfonyl, phenyl, 2-methoxycarbonylphenyl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl succinimide-2-yl, phenylacetic acid-1-methyl, succinic acid-2-methyl, 2-ureaacetic acid-1-yl, methyl succinate-2-methyl, propionic acid-1-yl, 1-acetylethyl, 1-benzoylethyl; X is selected from phthaloyl, oxalyl, urea N,N'-dimethyl, diphenylmethanediamine diacyl, hexamethylenediamine diacyl.

[0010] Further, in the above technical solution, in the most preferred case, the nitrification inhibitor is selected from One or more of the above.

[0011] Further, the corresponding salt is selected from sodium salt, potassium salt, lithium salt, quaternary ammonium salt (such as NH4, tetramethylamine, tetra-n-butylamine, etc.).

[0012] The present invention also provides a preparation method of the above nitrification inhibitor, including the following steps: reacting diketone with substituted hydrazine, or preparing by reacting pyrazole compound with different electrophilic reagents.

[0013] The present invention also provides the application of the above nitrification inhibitor in agricultural soil.

[0014] Further, in the above technical solution, when the nitrification inhibitor is applied in agricultural soil, the nitrification inhibitor is added to the nitrogen-containing fertilizer and then added to the soil.

[0015] Further, in the above technical solution, the nitrogen-containing fertilizer is selected from nitrogen-phosphorus-potassium compound fertilizer, ammonium sulfate, ammonium chloride, urea, ammonium phosphate, monoammonium phosphate, diammonium phosphate, ammonium nitrate, etc.

[0016] Further, in the above technical solution, the proportion of the nitrification inhibitor in the nitrogen content of the stable fertilizer is 0.1 - 2.0%, and the preferred content proportion is 0.1 - 0.5%.

[0017] Further, in the above technical solution, in the most preferred case, the nitrification inhibitor is selected from One or more of the above.

[0018] The present invention also provides a stable fertilizer containing the above nitrification inhibitor.

[0019] Further, in the above technical solution, the proportion of the nitrification inhibitor in the nitrogen content of the stable fertilizer is 0.1 - 2.0%, and the preferred content proportion is 0.1 - 0.5%.

[0020] Further, in the above technical solution, in the most preferred case, the inhibitor is selected from

[0021] One or more of the above.

[0022] Advantages of the invention

[0023] The compounds of the present invention have a novel structure and can effectively inhibit soil nitrification, which has many benefits for reducing nitrogen oxide emissions, nitrate leaching, improving nitrogen fertilizer utilization rate, improving crop yield and quality, etc. Detailed implementation manners

[0024] Example 1 Synthesis of a novel nitrification inhibitor

[0025] 1 - Acetyl - 3,5 - dimethylpyrazole (1): 340 mL of water and 170 g (2.3 mol) of acetylhydrazine were added to a round - bottom flask. 241.29 g (2.4 mol, 1.05 eq) of acetylacetone was slowly added dropwise at 0 - 10 °C, and then 41.34 g (0.69 mol, 0.3 eq) of acetic acid was slowly added dropwise. After the addition was complete, the reaction system was heated to 50 °C and maintained at this temperature for 3 hours. After the reaction, the mixture was allowed to stand for liquid - liquid separation, and the organic layer was distilled under reduced pressure to obtain 296 g of a colorless liquid product 1 with a yield of 93%.

[0026] 1 H NMR (400 MHz, DMSO - d6): δ 6.18 (s, 1H), 2.57 (s, 1H), 2.45 (s, 3H), 2.17 (s, 3H). LC - MS: 139.1 (M + H). HPLC 99.9%.

[0027] 1 - Acetyl - 3,4 - dimethylpyrazole / 1 - Acetyl - 4,5 - dimethylpyrazole (2): 106.7 g of 3,4 - dimethylpyrazole, 554.8 g of dichloromethane and 131.05 g (1.23 eq) of solid sodium bicarbonate powder were added to a three - necked flask. 102.05 g (0.96 eq) of acetyl chloride was added dropwise while controlling the temperature at (0 - 15 °C), and the reaction continued for 2 - 3 h. After the reaction, the mixture was filtered, and the filtrate was concentrated under reduced pressure to obtain an oily substance, which was further distilled under reduced pressure to obtain 147 g of a colorless liquid product 2 (a mixture of 2A + 2B) with a yield of 96%.

[0028] 1 H NMR (400 MHz, DMSO - d6): δ 8.06 (s, 3H), 2.57 (s, 1H), 7.60 (s, 0.07H), 2.59 (s, 0.3H), 2.54 (s, 3H), 2.40 (s, 0.3H), 2.17 (s, 0.3H), 1.98 (s, 3H), 1.95 (s, 0.3H). LC - MS: 139.1 (M + H).

[0029] 2 - (3,5 - dimethylpyrazol - 1 - yl) succinic acid (3): 20 g of 3,5 - dimethylpyrazole, 94.32 g of acetonitrile and 20.04 g (1.002 eq) of maleic anhydride were added to a single - necked flask. The mixture was heated to 60 °C and maintained at this temperature for 20 h. 100 mL (5V) of water was added, and the mixture was concentrated by rotary evaporation at 50 °C. 100 mL (5V) of water was added again, and the mixture was stirred at 60 °C for 2 h. Then, the temperature was slowly lowered to 0 - 10 °C and stirred for 1 - 2 h. The mixture was filtered, and the filter cake was washed 2 - 3 times with 60 - 80 mL (3 - 4V) of MTBE. The filter cake was dried in a forced - air oven at 45 °C for 20 hours to obtain 41 g of an off - white solid product 3 with a yield of 92%.

[0030] 1 H NMR (400 MHz, DMSO-d6): δ 12.76 (brs, 2H), 5.79 (s, 1H), 5.04 - 5.07 (q, 1H), 3.02 - 3.04 (q, 1H), 2.94 - 2.97 (q, 1H), 2.14 (s, 3H), 2.01 (s, 3H).

[0031] 2-(3 / 5-Methylpyrazol-1-yl)succinic acid (4): Add 20 g of 3-methylpyrazole, 78.6 g of acetonitrile, and 28.6 g (1.43 eq) of maleic anhydride to a single-necked flask. Heat to 40 °C and maintain this temperature for 20 h. Concentrate by rotary evaporation at 50 °C, add 20 mL (1V) of water, and slowly cool to 0 - 10 °C with stirring for 1 - 2 h. Filter by suction and wash the filter cake with ice water. Dry the filter cake in a blast dryer at 45 °C for 20 h to obtain 43 g of a white solid product 4 (a mixture of 4A + 4B), with a yield of 89%.

[0032] 1 H NMR (400 MHz, DMSO-d6): δ 12.72 (brs, 2.6H), 7.67 (s, 1H), 7.32 (s, 0.3H), 6.00 (s, 1.3H), 5.20 - 5.24 (q, 1.3H), 3.06 - 3.18 (q, 1.6H), 2.93 - 2.99 (q, 1H), 2.28 (s, 1H), 2.13 (s, 3H). HPLC 99.9%.

[0033] 2-(Pyrazol-1-yl)succinic acid (5): Add 400 mL of acetonitrile to a three-necked flask, add 50 g of pyrazole with stirring, then add 50.4 g (1.008 eq) of maleic anhydride. After addition, heat to 60 °C and react for 18 h. Control the temperature at 10 - 20 °C and slowly add dropwise 54 g (1.1 eq) of 43% KOH solution, resulting in a large amount of solid. Filter by suction, wash the filter cake with 100 - 150 mL of acetonitrile, and dry the filter cake in a blast dryer at 40 °C for 12 h to obtain 91.18 g of a white (slightly yellow) solid product 5.

[0034] 1 H NMR (400 MHz, D2O): δ 7.58 (d, J = 2.27 Hz, 1H), 7.45 (d, J = 1.7 Hz, 1H), 6.25 (t, J = 2.1 Hz, 1H), 5.17 (dd, J = 9.5, 5.4 Hz, 1H), 3.14 (dd, J = 16.7, 5.4 Hz, 1H), 3.02 (dd, J = 16.7, 9.5 Hz, 1H). HPLC 99.5%.

[0035] 3-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)propanoic acid (6): To a 100 mL three-necked flask, add DMP (9.6 g), acrylic acid (7.56 g, 0.788 eq), and 20 mL of water in sequence. The system is divided into two layers. Heat the system to 50 - 60 °C and react for 16 - 18 h. The system remains in two layers. Then heat it to 95 - 100 °C and react for 1 - 2 h until the system becomes homogeneous. Rotavaporize all volatile substances in the system at 60 °C under reduced pressure. After cooling, 10.2 g of a white waxy solid product 6 (a mixture of 6A + 6B) is obtained.

[0036] 1 1H NMR (DMSO-d6, 400 MHz): δ 1.89 - 1.92 (m, 3H), 2.04 - 2.15 (m, 3H), 2.69 - 2.79 (m, 2H), 4.13 - 4.20 (m, 2H), 7.15 - 7.31 (m, 1H). LC-MS: 169.1 (M + H).

[0037] 3,5-Dimethylpyrazole-1-carbothioamide (7): Add 400 g of water and 49.9 g of thiosemicarbazide to a 1 L three-necked flask. Dropwise add 54.8 g (1.096 eq) of acetylacetone while controlling the temperature at 0 - 5 °C, and then dropwise add 5.55 g (0.111 eq) of 36% hydrochloric acid while controlling the temperature at 10 - 15 °C. After the addition is complete, react at room temperature for 30 - 60 min. Monitor by TLC until the reaction is complete. Slowly cool the temperature to 0 - 10 °C and stir at this temperature for 30 min. Filter, wash the filter cake with ice water, and dry it in a blast dryer at 40 °C for 12 hours to obtain 82.77 g of a white solid product 7 with a yield of 97.5%.

[0038] 1 1H NMR (400 MHz, DMSO-d6): δ 9.57 (s, 1H), 9.16 (s, 1H), 6.19 (s, 1H), 2.65 (s, 3H), 2.17 (s, 3H).

[0039] 3-Methylpyrazole-1 / 2-carbothioamide (8): Add 480 mL of methanol to a three-necked flask. While stirring at 0 - 15 °C, add 41.38 g (0.69 eq) of thiosemicarbazide. Then add 60 g of 4,4-dimethoxy-2-butanone at 0 - 15 °C. Dropwise add 23.02 g (0.383 eq) of 36% HCl at 0 - 15 °C. After the addition is complete, react at room temperature for 5 - 6 h and monitor the reaction by TLC spotting. Heat the system to 60 °C and reflux for 2 h. Concentrate to dryness under vacuum at 40 °C. Add 300 mL of water and stir at 0 - 10 °C for 0.5 h. Filter and wash with ice water at 0 - 5 °C. Dry the filter cake at 40 °C to obtain a total of 30.75 g of solid product 8 (a mixture of 8A + 8B).

[0040] 1 1H NMR (400 MHz, DMSO-d6): δ 9.78 (s, 1H), 9.30 (s, 1H), 8.53 (d, J = 2.7 Hz, 1H), 6.38 (d, J = 2.7 Hz, 1H), 2.26 (s, 3H). LC-MS: 142.0 (M+H). HPLC 99.9%.

[0041] 3,4-Dimethylpyrazole-1-carboxamide (9): 20.5 g of 3,4-dimethylpyrazole, 160 g of water and 19.7 g (1.18 eq) of potassium cyanate were added to a three-necked flask, the temperature was controlled at 0 - 10 °C, and 24.3 g (1.26 eq) of 36% hydrochloric acid was slowly added dropwise through a constant pressure dropping funnel. Stirring was carried out at 0 - 10 °C for 4 - 5 hours, the raw materials were monitored by in-process control, filtered, and the obtained solid was dried in a forced air drying oven at 50 °C for 12 h to obtain 25.3 g of white solid product 9, with a yield of 91.0%.

[0042] 1 1H NMR (400 MHz, DMSO-d6): δ 7.92 (s, 1H), 7.54 (s, 2H), 2.15 (s, 3H), 1.97 (s, 3H). HPLC 99.5%.

[0043] 3,4 / 4,5-Dimethylpyrazole-1-p-toluenesulfonamide (10): 20.5 g of 3,4-dimethylpyrazole, 160 g of water and 19.7 g (1.18 eq) of potassium cyanate were added to a three-necked flask, the temperature was controlled at 0 - 10 °C, and 24.3 g (1.26 eq) of 36% hydrochloric acid was slowly added dropwise through a constant pressure dropping funnel. Stirring was carried out at 0 - 10 °C for 4 - 5 hours, the raw materials were monitored by in-process control, filtered, and the obtained solid was dried in a forced air drying oven at 50 °C for 12 h to obtain 25.3 g of white solid product 10 (a mixture of 10A + 10B), with a yield of 91.0%. 1 1H NMR (400 MHz, DMSO-d6) δ 8.09 (s, 1H), 7.79 (d, J = 8.4 Hz, 2H), 7.63 (s, 0.1H), 7.44 (d, J = 8.1 Hz, 2H), 2.40 (s, 0.46H), 2.38 (s, 3.46H), 2.08 (s, 3H), 1.93 (s, 3H), 1.89 (s, 0.46H). LC-MS: 251.1 (M+H). HPLC 99.6%.

[0044] 3,5-Dimethylpyrazole-1-p-toluenesulfonamide (11): Add 300 mL of ethanol, 100 g (1.00 eq) of p-toluenesulfonylhydrazide, and 53.8 g (0.538 eq) of acetylacetone to a three-necked flask. After adding, heat up to 85 °C and reflux for 5 h. Cool down and concentrate to a small amount of liquid, add water for slurrying and filter. Wash the filter cake with water, and dry the solid in a blast dryer at 40 °C to obtain 125.8 g of white solid product 11, with a yield of 93.6%.

[0045] 1 1H NMR (400 MHz, DMSO-d6): δ 7.80 (d, J = 8.4 Hz, 2H), 7.45 (d, J = 8.3 Hz, 2H), 6.14 (s, 1H), 2.47 (s, 3H), 2.39 (s, 3H), 2.09 (s, 3H). HPLC 99.9%.

[0046] N,N'-(Hexane-1,6-diyl)bis(3,5-dimethyl-1H-pyrazole-1-carboxamide) (12): Add 300 mL of acetonitrile and 34.3 g (1.14 eq) of 3,5-dimethylpyrazole to a three-necked flask. Cool down to 0 - 15 °C, and slowly add dropwise 30 g of 1,6-hexane diisocyanate. Keep the temperature at 0 - 15 °C and react for 3 h. Keep the temperature not higher than 35 °C, concentrate under reduced pressure to dryness, add water and stir at 0 - 5 °C, filter, and dry the filter cake at 40 °C. A total of 63.5 g of solid product 12 is obtained, with a yield of 98%.

[0047] 1 1H NMR (400 MHz, DMSO-d6): δ 8.14 (t, J = 5.9 Hz, 2H), 6.05 (s, 2H), 3.18 (dd, J = 13.6, 6.6 Hz, 4H), 2.44 (s, 6H), 2.16 (s, 6H), 1.60 - 1.43 (m, 4H), 1.29 (m, 4H). LC-MS: 361.2 (M + H).

[0048] N,N'-(Hexane-1,6-diyl)bis(3,4-dimethyl-1H-pyrazole-1-carboxamide) (13): Add 300 mL of acetonitrile and 34.3 g (1.14 eq) of 3,4-dimethylpyrazole to a three-necked flask. Cool down to 0 - 15 °C, and slowly add dropwise 30 g of 1,6-hexane diisocyanate. Keep the temperature at 0 - 15 °C and react for 3 h. Keep the temperature not higher than 35 °C, concentrate under reduced pressure to dryness, add water and stir at 0 - 5 °C, filter, and dry the filter cake at 40 °C. A total of 62 g of solid product 13 is obtained, with a yield of 97%.

[0049] 11H NMR (400 MHz, DMSO-d6): δ 8.24 (t, J = 5.8 Hz, 1H), 8.17 (t, J = 5.7 Hz, 1H), 7.93 (s, 1H), 7.46 (s, 1H), 3.18 (dd, J = 12.6, 6.2 Hz, 4H), 2.40 (s, 3H), 2.15 (s, 3H), 1.96 (s, 3H), 1.94 (s, 3H), 1.47 - 1.54 (m, 4H), 1.25 - 1.32 (m, 4H). LC-MS: 361.2 (M + H). HPLC 99.9%.

[0050] N,N'-(Methylenebis(4,1-phenylene))bis(3,4-dimethyl-1H-pyrazole-1-carboxamide) (14): 150 mL of acetonitrile and 30 g of 4,4'-diphenylmethane diisocyanate were added to a three-necked flask, and the temperature was lowered to 0 - 15 °C. A solution of 30 g of 3,4-dimethylpyrazole in acetonitrile (prepared by dissolving 30 g of 3,4-dimethylpyrazole in 150 mL of acetonitrile in advance) was slowly added dropwise. After the addition, the mixture was kept at 0 - 15 °C and reacted for 3 hours. The mixture was concentrated under reduced pressure to dryness, water was added, and the mixture was stirred at 0 - 5 °C, filtered, and the solid was dried at 40 °C to obtain 50.5 g of solid product 14 with a yield of 95%.

[0051] 1 1H NMR (400 MHz, DMSO-d6): δ 10.15 (s, 0.2H), 10.08 (s, 2H), 8.07 (s, 2H), 7.62 (d, J = 8.5 Hz, 4H), 7.20 (d, J = 8.4 Hz, 4H), 3.88 (s, 1.8H), 3.71 (s, 0.2H), 2.46 (s, 0.6H), 2.22 (s, 6H), 2.01 (s, 6H), 1.99 (s, 0.6H). LC-MS: 443.2 (M + H). HPLC 99.9%.

[0052] 1-((3,4-Dimethyl-1H-pyrazol-1-yl)methyl)urea (15): 15.0 g of 3,4-dimethylpyrazole, 13.4 g of 35 - 38 wt% formaldehyde, and 46.85 g of urea were added to a reaction flask, and 0.5 g of phosphoric acid was added dropwise. The mixture was stirred at 15 - 20 °C overnight. The mixture was filtered, washed with water, and the filter cake was dried at 45 °C to obtain 5.0 g of white solid product 15 with a yield of 19%.

[0053] 11H NMR (400 MHz, DMSO-d6): δ 7.42 (s), 7.18 (s), 6.59 (dt, J = 20.2, 7.4 Hz), 5.30 (d, J = 7.2 Hz), 5.20 (d, J = 7.4 Hz), 3.69 (s), 2.19 (s), 2.07 (s), 1.92 (s). LC-MS: 169.2 (M+H).

[0054] 1,3-Bis((3,4-dimethyl-1H-pyrazol-1-yl)methyl)urea (16): 15.0 g of DMP, 18 g (0.53 eq) of 35 - 38 wt% formaldehyde, and 12.6 g (0.65 eq) of urea were added into a reaction flask. 2.0 g (0.1 eq) of phosphoric acid was added dropwise. The mixture was stirred at 45 °C overnight, concentrated, dissolved in 100 mL of ethyl acetate, washed with 100 mL of 8.5% aqueous phosphoric acid solution, the organic phase was separated, the organic phase was concentrated, triturated with 30 mL of petroleum ether for 0.5 h, and the obtained filter cake was filtered and dried at 45 °C to obtain 18 g of a white solid product 16.

[0055] 1 1H NMR (400 MHz, DMSO-d6): δ 7.31 (s, 1H), 7.16 (s, 1H), 5.21 (d, J = 6.5 Hz, 1H), 5.11 (dd, J = 14.0, 6.6 Hz, 2H), 2.04 (s, 1H), 2.03 (s, 2H), 1.90 (s, 1H), 1.89 (s, 3H). LC-MS: 276.34 (M+H).

[0056] 3-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)pyrrolidine-2,5-dione (17): DMP (9.6 g), maleimide (10.7 g, 1.11 eq), and 20 mL of water were added into a three-necked flask. The temperature was raised to 100 - 110 °C and reacted for 16 h. The mixture was naturally cooled to 10 - 20 °C with stirring for 4 h, and a solid precipitated. It was stirred for 2 h under ice-water cooling, filtered, and the filter cake was washed with water twice to obtain the product, which was dried in a blast dryer at 45 - 50 °C for 20 h. After weighing, 12 g of a pink powder product 17 (a mixture of 17A + 17B) was obtained. 1 1H NMR (DMSO-d6, 400 MHz): δ 1.90 - 1.93 (m, 3H), 2.03 - 2.07 (m, 3H), 2.87 - 2.92 (m, 1H), 3.10 - 3.19 (m, 1H), 5.29 - 5.47 (m, 1H), 7.25 - 7.54 (m, 1H), 10.47 (brs, 1H). LC-MS: 194.1 (M+H).

[0057] 2-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)pyridine (18): 3,4-Dimethylpyrazole (7.03 g, 0.70 eq), copper(I) oxide (0.14 g, 0.01 eq), N1,N2-bis(furan-2-ylmethyl)oxalamide (0.24 g, 0.02 eq), potassium phosphate (20.71 g, 2.07 eq), acetonitrile (50 mL) and 2-iodopyridine (10.00 g) were successively added to a three-necked flask. After purging with nitrogen three times, the temperature was raised to 80 - 90 °C and the reaction was carried out for 142 h. TLC showed that there was almost no 2-iodopyridine left. Heating was stopped, and the mixture was allowed to cool naturally to 20 - 30 °C with stirring. The insoluble substances were removed by filtration through diatomaceous earth, and the filter cake was washed with acetonitrile. The filtrate was collected and concentrated to obtain a yellow oil. The product was purified by flash column chromatography using petroleum ether and concentrated to obtain 4.98 g of off-white crystals (slightly yellowish) of product 18 (a mixture of 18A and 18B), with a yield of 58.9%.

[0058] 1 H NMR (400 MHz, DMSO-d6) δ 8.48 (ddd, J = 4.8, 3.6, 2.4 Hz, 1H), 8.41 (ddd, J = 4.8, 1.7, 0.7 Hz, 1H), 8.31 (s, 1H), 8.00 - 7.88 (m, 1H), 7.83 (dd, J = 8.3, 4.0 Hz, 1H), 7.53 (s, 1H), 7.37 - 7.29 (m, 1H), 7.30 - 7.14 (m, 1H), 2.21 (s, 3H), 2.03 (d, J = 0.7 Hz, 3H), 2.02 (s, 3H). LC-MS: 174.1 (M + H).

[0059] 3-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)pyridine (19): Under nitrogen protection, acetonitrile (75 mL), DMP (7.0 g, 0.7 eq), Cu2O (0.14 g, 0.01 eq), BMFO (0.24 g, 0.01 eq), K3PO4 (20.7 g, 2.1 eq) and 3-iodopyridine (10 g) were added to a three-necked flask. The mixture was refluxed for 72 h, and the color gradually changed from pink to brown-yellow. Heating was stopped, and the mixture was allowed to cool naturally to 30 - 50 °C with stirring. The insoluble substances were removed by filtration through diatomaceous earth, and the filter cake was washed with ethyl acetate. The filtrate was collected, 20 g of silica gel (200 - 300 mesh) was added, and the mixture was concentrated to dryness under vacuum at 40 - 45 °C. Column chromatography was carried out using PE / EA = 10 / 1, and then separated using PE / EA = 5 / 1 to obtain 4.5 g of a yellow oil of 19 (a mixture of 19A and 19B), with a yield of 53.3%.

[0060] 11H NMR (400 MHz, DMSO-d6): δ 9.04 (d, J = 2.6 Hz, 1H), 8.79 (d, J = 2.5 Hz, 0.3H), 8.61 (dd, J = 4.7, 1.4 Hz, 0.3H), 8.44 (dd, J = 4.7, 1.3 Hz, 1H), 8.25 (s, 1H), 7.96 (m, J = 8.2, 2.4, 1.5 Hz, 0.3H), 7.52 (s, 0.3H), 7.47 (dd, J = 8.3, 4.7 Hz, 1H), 2.27 (d, J = 4.7 Hz, 1H), 2.20 (d, J = 7.6 Hz, 3H), 2.03 (s, 3H), 2.00 (s, 1H). LC-MS: 174.1 (M+H).

[0061] 4-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)pyridine (20): 10 g of 4-iodopyridine was added to a reaction flask, 7.0 g (0.73 eq) of DMP was added to the reaction flask, 0.14 g (0.014 eq) of cuprous oxide was added to the reaction flask, 0.24 g (0.024 eq) of BFMO was added to the reaction flask, 20.7 g (2.0 eq) of potassium phosphate was added to the reaction flask. The flask was purged with nitrogen three times, 50 mL of acetonitrile was added, and the reaction was carried out at 85 °C for 72 h. When DMP was almost completely reacted, the reaction solution was allowed to cool to room temperature naturally, filtered, the filtrate was concentrated to dryness, and column chromatography was performed with dry loading to obtain 2.3 g of a yellow solid 20 (a mixture of 20A + 20B).

[0062] 1 1H NMR (400 MHz, DMSO-d6): δ 8.66 (dd, J = 4.6, 1.6 Hz, 1H), 8.62 - 8.49 (m, 4H), 8.36 (s, 2H), 7.72 (dd, J = 4.7, 1.6 Hz, 4H), 7.61 (dd, J = 4.6, 1.6 Hz, 1H), 7.56 (d, J = 7.0 Hz, 1H), 2.37 (d, J = 7.5 Hz, 1H), 2.20 (s, 6H), 2.03 (d, J = 0.6 Hz, 6H), 2.02 (s, 2H). LC-MS: 174.1 (M+H).

[0063] 3,4 / 4,5-Dimethyl-1-phenyl-1H-pyrazole (21): Under nitrogen protection, add acetonitrile (12 mL), DMP (0.85 g, 0.43 eq), Cu2O (0.04 g, 0.02 eq), BMFO (0.07 g, 0.02 eq), K3PO4 (3.4 g, 1.7 eq) and iodobenzene (2 g) into a three-necked flask, heat to reflux for 48 h, the color gradually changes from pink to brownish yellow, stop heating, and naturally cool to 30 - 50 °C with stirring. Filter through diatomaceous earth to remove insoluble substances, wash with ethyl acetate, collect the filtrate, add 4 g of silica gel with 200 - 300 mesh, concentrate to dryness under vacuum at 40 - 45 °C, and perform column chromatography with PE / EA = 40 / 1 and then PE / EA = 30 / 1 to obtain 0.6 g of yellow oil 21 (a mixture of 21A and 21B), with a yield of 35%.

[0064] 1 H NMR (400 MHz, DMSO-d6): δ 8.14 (s, 1H), 7.73 (d, J = 7.7 Hz, 2H), 7.48 - 7.40 (m, 2H), 7.21 (t, J = 7.4 Hz, 1H), 2.19 (s, 3H), 2.02 (s, 3H). LC-MS: 173.1 (M + H).

[0065] Methyl 2-(3,4 / 4,5-dimethyl-1H-pyrazol-1-yl)benzoate (22): Under nitrogen protection, add acetonitrile (50 mL), DMP (5.5 g, 0.55 eq), Cu2O (0.16 g, 0.01 eq), BFMO (0.28 g, 0.03 eq), K3PO4 (16.18 g, 1.62 eq) and methyl 2-iodobenzoate (10 g) into a three-necked flask; heat to 85 - 95 °C for reaction; react for 22 - 24 h, with a small amount of methyl 2-iodobenzoate remaining by TLC; stop heating, and naturally cool to 10 - 30 °C with stirring; filter through diatomaceous earth and wash with acetonitrile; after vacuum concentration, obtain the crude product, and perform column chromatography to obtain 3.42 g of pale yellow oil 22 (a mixture of 22A and 22B), with a yield of 38.9%.

[0066] 1 H NMR (400 MHz, DMSO-d6): δ 7.87 (s, 1H), 7.68 - 7.49 (m, 3H), 7.43 - 7.32 (m, 1H), 3.64 (d, J = 5.4 Hz, 3H), 2.13 (s, 3H), 2.01 (d, J = 0.7 Hz, 3H). LC-MS: 231.1 (M + H).

[0067] 1,2-Bis(3,4 / 4,5-dimethyl-1H-pyrazol-1-yl)ethan-1-one (23): Add 15.0 g of DMP and 100 mL of THF to a reaction flask. Control the temperature at 5 - 15 °C with an ice-salt bath and add 8.0 g (0.53 eq) of oxalyl chloride dropwise to the reaction flask. Stir for 30 min. Control the temperature at 15 - 25 °C with an ice-salt bath and add 15.7 g (1.05 eq) of triethylamine to the reaction flask. Stir overnight, filter, concentrate the filtrate, dissolve it in 100 mL of ethyl acetate, wash it with 100 mL of 8.5% aqueous phosphoric acid solution, concentrate the organic phase, triturate with petroleum ether and filter, and dry at 45 °C to obtain 3.65 g of a white solid 23 (a mixture of 23A + 23B + 23C).

[0068] 1 H NMR (400 MHz, DMSO-d6): δ 8.30 (s, 2H), 2.12 (s, 6H), 2.03 (s, 6H). LC-MS: 247.1 (M + H).

[0069] (1,4-Terephthaloyl)(3,4 / 4,5-dimethyl-1H-pyrazole (24): In a three-necked reaction flask, add 15.0 g of DMP and 30 mL of THF. Dissolve 15.08 g of terephthaloyl chloride in 150 mL of THF, control the temperature at 5 - 15 °C with an ice-salt bath and add it dropwise to the reaction flask. Stir for 30 min. Control the temperature at 15 - 25 °C with an ice-salt bath and add 18.7 g of triethylamine to the reaction flask and stir overnight. Filter, concentrate the filtrate, triturate the resulting solid in water and filter, wash with petroleum ether, filter, and dry at 45 °C to obtain 14.9 g of a white solid 24 (a mixture of 24A + 24B + 24C).

[0070] 1 H NMR (400 MHz, DMSO-d6): δ 8.29 (s, 2H), 8.04 (s, 4H), 2.20 (s, 6H), 2.05 (t, J = 4.5 Hz, 6H). LC-MS: 323.2 (M + H).

[0071] 3-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)-1-phenylpropanone (25): Add 10 mL of 50% aqueous ethanol solution, 2.0 g of DMP, and 5.3 g of 3-(dimethylamino)-1-phenylpropanone hydrochloride to a three-necked flask in sequence. Heat to 85 - 95 °C and react for 6 h; concentrate the ethanol, dilute with water and disperse; extract with ethyl acetate, separate the layers; wash the organic phase with saturated brine, separate the layers; concentrate to obtain a yellow oil, and cool to crystallize to obtain 4.61 g of a pale yellow crystal 25 (a mixture of 25A + 25B), with a yield of 97%.

[0072] 11H NMR (400 MHz, DMSO-d6): δ 8.01 - 7.92 (m, 2H), 7.68 - 7.58 (m, 1H), 7.52 (t, J = 7.6 Hz, 2H), 7.39 (s, 1H), 7.13 (s, 1H), 4.31 (t, J = 6.7 Hz, 2H), 3.55 (td, J = 6.7, 3.2 Hz, 2H), 2.20 (s, 3H), 2.03 (s, 3H), 1.90 (s, 3H), 1.89 (s, 3H). LC-MS: 229.1 (M + H).

[0073] 4-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)butan-2-one (26): To a three-necked flask were successively added 50% aqueous ethanol solution (20 mL), DMP (10.57 g), and 4-dimethylamino-2-butanone hydrochloride (20.01 g, 1.9 eq). The temperature was raised to 85 - 95 °C and the reaction was carried out for 19 h; the ethanol was concentrated off, diluted with water and dispersed; extracted with ethyl acetate and separated; the organic phase was washed with saturated brine solution and separated; concentrated to obtain a yellow oil 14.71 g; purified by wet column chromatography with PE / EA = 20:1 - 3:1 to obtain the product 26 (a mixture of 26A + 26B) 8.07 g (isomer ratio 2:1), yield 44.1%.

[0074] 1 1H NMR (400 MHz, DMSO-d6): δ 7.31 (d, J = 7.8 Hz, 1H), 7.12 (s, 1H), 4.11 (tt, J = 6.8, 3.4 Hz, 2H), 2.99 - 2.83 (m, 2H), 2.08 (d, J = 7.4 Hz, 3H), 2.06 - 2.01 (m, 2H), 1.99 (s, 1H), 1.89 (d, J = 4.5 Hz, 3H). LC-MS: 167.1 (M + H).

[0075] 3-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)-2-phenylpropanoic acid (27): To a three-necked flask were added 3,4-dimethylpyrazole (6.17 g), atropic acid (9.98 g, 1.6 eq), and 18.5 mL of water; the temperature was raised to 100 - 110 °C and the reaction was carried out for 20 h; the heating was stopped and the temperature was allowed to cool naturally to 20 - 30 °C with stirring; filtered; the filter cake was dissolved in hot ethyl acetate; concentrated and then slurried with methyl tert-butyl ether; filtered; the filter cake was dried to obtain a white powder 27 (a mixture of 27A + 27B) 12.5 g, yield 79.67%.

[0076] 11H NMR (400 MHz, DMSO-d6): δ 12.59 (s, 1H), 7.39 - 7.25 (m, 5H), 7.22 (s, 1H), 7.17 (s, 1H), 4.55 (ddd, J = 11.5, 6.5, 2.7 Hz, 1H), 4.22 - 4.07 (m, 2H), 2.03 (s, 2H), 1.96 (s, 1H), 1.85 (s, 3H). LC-MS: 245.2 (M + H).

[0077] 2-((3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)methyl)succinic acid (28): 20 g of DMP, 28.4 g of itaconic acid and 40 mL of water were successively added to a three-necked flask; the temperature was raised to 100 - 110 °C and reacted for 22 h; heating was stopped and there was no remaining of the two raw materials by TLC; the temperature was naturally cooled to 20 - 30 °C with stirring; water was added for pulping; filtration was carried out, and the filter cake was washed with water; the filter cake was dried to obtain 26.48 g of a white powder 28 (a mixture of 28A + 28B), with a yield of 56.2%.

[0078] 1 1H NMR (400 MHz, DMSO-d6): δ 12.39 (s, 2H), 7.31 (s, 1H), 4.25 (d, J = 5.8 Hz, 1H), 4.21 (d, J = 5.8 Hz, 1H), 4.15 (d, J = 7.1 Hz, 1H), 4.12 (d, J = 7.1 Hz, 1H), 2.41 (d, J = 8.7 Hz, 1H), 2.37 (d, J = 8.7 Hz, 1H), 2.29 (d, J = 4.8 Hz, 1H), 2.25 (d, J = 4.7 Hz, 1H), 2.04 (s, 3H), 1.90 (s, 3H). LC-MS: 227.1 (M + H).

[0079] 3-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)butyric acid (29): DMP (9.6 g), crotonic acid (9 g, 0.94 eq) and 20 mL of water were successively added to a three-necked flask, the temperature was raised to 100 - 110 °C and reacted for 20 h, heating was stopped, the temperature was naturally cooled to 20 - 30 °C with stirring, water was removed by vacuum concentration at 60 - 65 °C, the residue was added with 60 mL of ethyl acetate, concentrated to a small volume at 40 - 45 °C under vacuum and replaced with MTBE, concentrated to a small volume at 30 - 35 °C under vacuum until a solid precipitated, transferred to an ice-water bath and stirred for 15 min, filtered, washed with MTBE, and dried in a blast dryer at 45 °C for 8 - 12 h, weighed to obtain 10.26 g of a white solid powder 29 (a mixture of 29A + 29B), with a yield of 56%.

[0080] 11H NMR (400 MHz, DMSO-d6): δ 12.24 (s, 1H), 7.36 (s, 1H), 4.62 - 4.45 (m, 1H), 2.77 (dd, J = 16.0, 7.7 Hz, 1H), 2.63 (dd, J = 16.0, 6.4 Hz, 1H), 2.04 (s, 3H), 1.89 (s, 3H), 1.34 (d, J = 6.7 Hz, 3H). LC-MS: 183.2 (M + H).

[0081] Dimethyl 2-((3,4-dimethyl-1H-pyrazol-1-yl)methyl)succinate (30): To a three-necked flask, DMP (11.6 g), dimethyl itaconate (20 g, 1.7 eq) and 25 mL of water were added successively. The temperature was raised to 100 - 110 °C and the reaction was carried out for 30 h. Then, it was cooled naturally to 20 - 30 °C with stirring. Water was removed by vacuum concentration at 60 - 65 °C. The residue was added with 60 mL of ethyl acetate, and then concentrated to a small volume at 40 - 45 °C and replaced with MTBE. It was concentrated under vacuum at 40 - 45 °C until no obvious distillate was distilled out. After weighing, 28.67 g of a pale yellow oil 30 (a mixture of 30A + 30B) was obtained, with a yield of 93%.

[0082] 1 1H NMR (400 MHz, DMSO-d6): δ 7.31 (s, 1H), 7.17 (s, 1H), 4.31 - 4.22 (m, 2H), 4.21 - 4.14 (m, 2H), 3.59 (d, J = 9.7 Hz, 12H), 3.29 - 3.16 (m, 2H), 2.61 - 2.52 (m, 2H), 2.50 - 2.40 (m, 2H), 2.12 (s, 3H), 2.04 (s, 3H), 1.92 (d, J = 5.8 Hz, 3H), 1.90 (s, 3H). LC-MS: 255.1 (M + H).

[0083] 3-(3,4 / 4,5-Dimethyl-1H-pyrazol-1-yl)-2-methylpropanoic acid (31): 9.6 g of DMP was added to a reaction flask, 8.6 g (0.9 eq) of methacrylic acid was added, 2V of water was added, and the temperature was raised to 105 °C for 28 h. After cooling, 30 mL of water was added, 2 g of 85% phosphoric acid was added, and 50 mL of ethyl acetate was added. It was washed with acid water three times, and the organic phase was concentrated to obtain 8.5 g of an oily substance 31 (a mixture of 31A + 31B).

[0084] 11H NMR (400 MHz, DMSO-d6): δ 12.34 (s), 7.31 (s), 7.16 (s), 6.02 - 5.95 (m), 5.75 (s), 5.69 - 5.46 (m), 4.20 (ddd, J = 20.7, 13.3, 6.9 Hz), 4.02 - 3.84 (m), 2.86 (ddt, J = 28.2, 14.1, 7.1 Hz), 2.14 (s), 2.04 (s), 1.90 (s), 1.89 (s), 1.86 - 1.79 (m), 1.07 - 0.91 (m). LC-MS: 183.2 (M + H).

[0085] 2-(3,4-Dimethyl-1H-pyrazol-1-yl)-2-ureidoacetic acid (32): Glyoxylic acid (55%) (7.7 g, 1.1 eq), 3,4-dimethylpyrazole (5.0 g, 1.0 eq), urea (3.4 g, 1.1 eq), water (50 mL) and 0.3 g of phosphoric acid were successively added to a three-necked flask, and the temperature was raised to 45 - 55 °C for reaction for 24 h; heating was stopped, and the temperature was naturally lowered to 20 - 30 °C with stirring; filtration was carried out, and the filter cake was washed with water; drying was carried out at 50 °C to obtain 9.11 g of white powder 32, with a yield of 82.5%.

[0086] 1 1H NMR (400 MHz, DMSO-d6): δ 7.45 (s, 1H), 7.24 (d, J = 8.9 Hz, 1H), 6.14 (d, J = 8.9 Hz, 1H), 5.91 (s, 2H), 2.04 (s, 3H), 1.91 (s, 3H). LC-MS: 169.1 (M + H).

[0087] Example 2

[0088] The nitrification inhibition rate of the national standard soil culture was evaluated for 3,4-dimethylpyrazole phosphate (DMPP) and the nitrification inhibitor of the present invention according to the methods and requirements of GBT 35113-2017. The nitrification inhibition rates of DMPP and the nitrification inhibitor (both added at an equivalent DMP (3,4-dimethylpyrazole) N addition amount of 0.25%) were added to compound fertilizer (N15-P15-K15) or ammonium sulfate (N20-P0-K0).

[0089] The soil used in this experiment was collected from two different locations in China: (i) paddy soil for rice cultivation from Shouxian County, Anhui Province (116°27, N, 31°54, E), (ii) corn cultivation soil from Quzhou County, Hebei Province (114.92, E, 36.78, N).

[0090] Table 1: Basic properties of the soil

[0091]

[0092] Table 2: Nitrification inhibition rates of different nitrification inhibitors added to 15-15-15 compound fertilizer and ammonium sulfate

[0093]

[0094]

[0095] Example 3 Stability of the preferred nitrification inhibitor on ammonium sulfate (20-0-0) (compared with DMPP)

[0096] 3,4-Dimethylpyrazole phosphate (DMPP) and the nitrification inhibitors 3, 7, 8, 17, 19 of the present invention were all sprayed into ammonium sulfate (20-0-0) at an equivalent DMP (3,4-dimethylpyrazole) N of 0.25%.

[0097] Preparation of spraying solution: Weigh 70 g of dimethyl sulfoxide (DMSO) solution and add 30 g of 3,4-dimethylpyrazole phosphate (DMPP) to prepare an inhibitor solution with a mass fraction of 30%. Other preferred inhibitors were also prepared according to this method.

[0098] Method for outer coating of nitrogen fertilizer synergist on fertilizer: Weigh 1000 g of ammonium sulfate (20-0-0) and add it to a small rotary drum coating machine. Adjust the rotation speed to 20 r / min and the temperature to 25-30 °C for preheating. Load the prepared inhibitor solution into a small sprayer and spray it evenly multiple times. After uniform coating, take it out and air-dry it, then sub-pack it and store it in a constant temperature and humidity box at 25 and 45 °C. Detect the change in the inhibition content every 0, 10, 20, and 30 days.

[0099] Table 3: Content changes of different nitrification inhibitors added to ammonium sulfate (20-0-0)

[0100]

[0101] Example 4 Soil ammonium nitrogen and nitrate nitrogen contents in field application (preferred compounds compared with DMPP)

[0102] 3,4-Dimethylpyrazole phosphate (DMPP) and the nitrification inhibitor compounds 3, 7, 8, 17, 19, and DMPP of the present invention were all added to ammonium sulfate (20-0-0) at an equivalent DMP (3,4-dimethylpyrazole) N addition amount of 0.25% and applied during the tillering stage of rice. Samples were taken regularly to detect the soil ammonium nitrogen and nitrate nitrogen contents.

[0103] Table 4: Soil ammonium nitrogen and nitrate nitrogen contents at different times after adding several nitrification inhibitor products to ammonium sulfate

[0104]

[0105]

[0106] Example 5 Field Application Effect (Preferred Compound vs. DMPP Control)

[0107] A field plot experiment of applying ammonium sulfate with 3,4-dimethylpyrazole phosphate (DMPP) and the preferred new nitrification inhibitor compound of the present invention was carried out on irrigated desert soil in Zhangye, Gansu. Both DMPP and the preferred nitrification inhibitor compound were added to ammonium sulfate (20-0-0) at an equivalent DMP (3,4-dimethylpyrazole) N addition amount of 0.25%, topdressed at the large flare stage of maize, and fresh samples were taken on the 7th, 14th, 28th, and 49th days after topdressing to measure soil ammonium nitrogen and nitrate nitrogen, and finally the yield was measured and indexes such as ear length, bald tip length, and 100-grain weight were collected.

[0108] Table 5: Contents of soil ammonium nitrogen and nitrate nitrogen at different times when the preferred nitrification inhibitor product is applied with ammonium sulfate

[0109]

[0110] Table 6: Field performance of the preferred nitrification inhibitor product applied with ammonium sulfate

[0111]

[0112]

[0113] The above is only the preferred embodiment of the present invention. It should be noted that the above preferred embodiment should not be regarded as a limitation to the present invention. The protection scope of the present invention should be subject to the scope defined by the claims. For those of ordinary skill in the art of this technology, within the spirit and scope of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A nitrification inhibitor, characterized in that: include: Compound A, a salt of compound A, compound B, a salt of compound B; Compound A is a single compound and a mixture of isomers at positions 3, 4 and 4, 5 on the pyrazole ring; Compound B is a single compound and a mixture of isomers at positions 3, 4 and 4, 5 on the pyrazole ring; the general structural formula of the nitrification inhibitor is: Where: R 1 and R 2 Each is independently selected from hydrogen or C1-C6 alkyl; R is selected from C2-C6 alkanoyl, benzoyl, succinic acid-2-yl, aminothiocarbonyl, aminocarbonyl, substituted benzenesulfonyl, substituted phenyl, pyridyl, succinimidyl-2-yl, substituted phenylacetic acid-1-(C1-C4) alkyl, succinic acid-2-(C1-C4) alkyl, 2-ureaacetic acid-1-yl, succinic acid (C1-C4) alkyl ester-2-(C1-C4) alkyl, carboxyl substituted (C1-C4) alkyl. C4) straight chain or branched alkyl, acyl substituted C1-C4 alkyl; wherein the substituents in substituted benzenesulfonyl, substituted phenyl, substituted phenylacetic acid-1-(C1-C4) alkyl are all selected from hydrogen, C1-C4 alkoxycarbonyl, halogen or C1-C4 alkyl, and the acyl substitution is selected from acetyl or benzoyl; X is selected from phthaloyl, oxalyl, urea N,N'-di(C1-C4) alkyl, diphenylmethanediaminodiacyl, C1-C6 alkyldiaminodiacyl.

2. The nitrification inhibitor according to claim 1, characterized in that: R 1 and R 2 Each is independently selected from hydrogen or methyl; R is selected from acetyl, benzoyl, succinic acid-2-yl, aminothiocarbonyl, aminocarbonyl, p-toluenesulfonyl, phenyl, 2-methoxycarbonylphenyl, pyridin-2-yl, pyridin-3-yl, pyridin-4-ylsuccinimidyl-2-yl, phenylacetic acid-1-methyl, succinic acid-2-methyl, 2-ureaacetic acid-1-yl, succinic acid methyl ester-2-methyl, propionic acid-1-yl, 1-acetylethyl, 1-benzoylethyl; X is selected from phthaloyl, oxalyl, urea N,N'-dimethyl, diphenylmethanediaminodiyl, hexamethylenediaminediyl.

3. The nitrification inhibitor according to claim 2, characterized in that: The nitrification inhibitor is selected from One or more of .

4. The nitrification inhibitor according to claim 1, characterized in that: The salt is selected from sodium salt, potassium salt, lithium salt, and quaternary ammonium salt.

5. The method for preparing the nitrification inhibitor according to claims 1-3, characterized in that: The method comprises the following steps: preparing the product by reacting diketone with substituted hydrazine, or by reacting a pyrazole compound with different electrophilic reagents.

6. Use of the nitrification inhibitor according to claims 1-4 in agricultural soil.

7. The use of the nitrification inhibitor in agricultural soil according to claim 6, characterized in that: Add nitrification inhibitor compounds to nitrogen-containing fertilizers added to the soil.

8. The use of the nitrification inhibitor in agricultural soil according to claim 7, characterized in that: The nitrogen-containing fertilizer is selected from nitrogen-phosphorus-potassium compound fertilizer, ammonium sulfate, ammonium chloride, urea, ammonium phosphate, monoammonium phosphate, diammonium phosphate, and ammonium nitrate.

9. The use of the nitrification inhibitor in agricultural crops according to claim 6, characterized in that: The nitrification inhibitor accounts for 0.1-2.0% of the nitrogen content of the nitrogen-containing fertilizer.

10. A stable fertilizer containing the nitrification inhibitor according to any one of claims 1 to 4.

11. The stable fertilizer of nitrification inhibitor according to claim 10, characterized in that: The nitrification inhibitor accounts for 0.1-2.0% of the nitrogen content of the stable fertilizer, and the preferred content is 0.25%.

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