Bifunctional pyrazole chelated nitrogen fertilizer inhibitor as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fertilizer synergists, in particular to a bifunctional pyrazole chelating nitrogen fertilizer inhibitor and a preparation method and application thereof.The preparation method comprises the following steps that CuCl2. 2H2O and 3, 5-dimethyl-4-bromopyrazole are placed in a container according to a certain molar ratio; the preparation method comprises the following steps: adding absolute ethyl alcohol and water into a container according to a certain volume ratio, and completely dissolving CuCl2. 2H2O and 3, 5-dimethyl-4-bromopyrazole; sealing the container, pricking holes, and standing at room temperature for 1-3 days to obtain blue blocky crystals; and washing, filtering and drying the blue blocky crystals to obtain the bifunctional pyrazole chelated nitrogen fertilizer inhibitor. According to the invention, copper chloride dihydrate and 3, 5-dimethyl-4-bromopyrazole are used as raw materials, and the bifunctional pyrazole chelated nitrogen fertilizer inhibitor is prepared by using a mixed solution volatilization method under a certain proportion, so that the loss of nitrogen can be effectively reduced, and the utilization rate of the fertilizer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fertilizer synergists, and particularly provides a bifunctional pyrazole chelated nitrogen fertilizer inhibitor, a preparation method and an application thereof. Using copper chloride dihydrate and 3,5-dimethyl-4-bromopyrazole as raw materials, a bifunctional pyrazole chelated nitrogen fertilizer inhibitor is prepared by the method of volatilization of a mixed solution in a certain proportion, which can effectively reduce the loss of nitrogen and improve the utilization rate of fertilizers. Background Art

[0002] 3,5-Dimethyl-4-bromopyrazole is a typical derivative of pyrazole, which is a kind of organic compound with a unique chemical structure containing halogen and pyrazole ring and good biological activity, and has broad application potential in the agricultural and environmental fields. Pyrazole compounds have been proven to be able to effectively inhibit the activity of nitrifying bacteria and inhibit their growth and activity by affecting the gene expression of nitrifying bacteria. Thus, the emission of nitrogen oxides is reduced. For example, 3,4-dimethylbromopyrazole phosphate (DMPP), as a widely used nitrification inhibitor, can significantly inhibit nitrification in soil, reduce the emission of greenhouse gases such as N2O, improve the utilization rate of nitrogen elements in fertilizers and reduce the nitrogen loss of fertilizers.

[0003] However, the pyrazole ring contained in the pyrazole derivative nitrification inhibitor has dangerous characteristics such as low melting point, strong volatility, large irritation, and flammability. It is very easy to decompose and deteriorate at room temperature, which has a great impact on the environment. Moreover, as a nitrogen fertilizer inhibitor, it can only inhibit nitrifying bacteria and does not have a dual inhibition function, and the addition amount is relatively large during the use as a nitrogen fertilizer synergist. In order to solve the disadvantages of 3,5-dimethyl-4-bromopyrazole such as poor stability, single function, and large irritation, and to expand its application in the fertilizer field, therefore, chelation modification of 3,5-dimethyl-4-bromopyrazole is required. It is expected that while significantly improving its stability, it can have a dual inhibition function, effectively reduce the usage amount, improve the utilization efficiency of nitrogen fertilizers and reduce the secondary pollution of the environment and soil caused by fertilizers during release. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a bifunctional pyrazole chelated nitrogen fertilizer inhibitor, a preparation method and an application thereof.

[0005] The present invention is realized as follows. A preparation method of a bifunctional pyrazole chelated nitrogen fertilizer inhibitor is provided, including the following steps:

[0006] 1) Place CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole in a container according to a certain molar ratio;

[0007] 2) Add absolute ethanol and water to the container according to a certain volume ratio to completely dissolve CuCl2· 2H2O and 3,5-dimethyl-4-bromopyrazole;

[0008] 4) After sealing and puncturing the container, let it stand at room temperature for 1 - 3 days to obtain blue block crystals;

[0009] 4) Wash, filter and dry the blue block crystals to obtain a bifunctional pyrazole chelating nitrogen fertilizer inhibitor.

[0010] Preferably, in the step 1), the molar ratio of CuCl 2· 2H2O to 3,5-dimethyl-4-bromopyrazole is 1:1 - 3.

[0011] Preferably, in the step 2), the volume ratio of absolute ethanol to water is 1:1 - 3.

[0012] A bifunctional pyrazole chelating nitrogen fertilizer inhibitor is provided, which is prepared based on the above method.

[0013] Preferably, the chemical formula of the bifunctional pyrazole chelating nitrogen fertilizer inhibitor is C 10 H 14 Br2Cl2CuN4, and the structural formula is:

[0014]

[0015] Preferably, the crystal form of the structure of the bifunctional pyrazole chelating nitrogen fertilizer inhibitor is monoclinic system, and the space group is P21 / c.

[0016] An application of the bifunctional pyrazole chelating nitrogen fertilizer inhibitor is provided, which is used as an urease and nitrifying bacteria inhibitor in fertilizers.

[0017] Preferably, the fertilizer is a nitrogen fertilizer.

[0018] Preferably, the nitrogen fertilizer is urea.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] The present invention provides a preparation method and application of a bifunctional pyrazole chelating nitrogen fertilizer inhibitor. The bifunctional pyrazole chelating nitrogen fertilizer inhibitor prepared by the present invention has good inhibitory effects on urease and nitrifying bacteria, can slow down the hydrolysis rate of urea and reduce the production of nitrate nitrogen simultaneously, so as to ensure that nitrogen fertilizer exists in the soil for a longer time and is fully absorbed and utilized by plants. The preparation method is simple, and the solvents used are only absolute ethanol and water. The preparation process does not consume energy and does not cause solvent pollution, having good application prospects. A bifunctional pyrazole chelating nitrogen fertilizer inhibitor prepared by the present invention is a dual-functional inhibitor, which has the advantages of high inhibition rate, extremely low dosage, low volatility, good stability, low toxicity, and being friendly to soil and environment. Therefore, it can be widely added and applied in fertilizers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described in detail below in conjunction with the drawings and embodiments:

[0022] Figure 1 It is a single crystal coordination environment diagram of the bifunctional pyrazole chelating nitrogen fertilizer inhibitor prepared in Example 1;

[0023] Figure 2 It is a comparison diagram of the powder X-ray diffraction pattern of the bifunctional pyrazole chelating nitrogen fertilizer inhibitor prepared in Example 1 and the simulated diagram of single crystal data;

[0024] Figure 3 It is an inhibition diagram of the bifunctional pyrazole chelating nitrogen fertilizer inhibitor prepared in Example 1 with different concentrations on urease. SPECIFIC EMBODIMENTS

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] The present invention chelates and coordinates the central copper atom of 3,5-dimethyl-4-bromopyrazole and copper chloride dihydrate by the solvent evaporation method. While increasing the stability of 3,5-dimethyl-4-bromopyrazole, its properties are further optimized and improved, so that it only has the dual inhibitory functions on urease and nitrifying bacteria, and has significant advantages in improving fertilizer utilization rate, reducing environmental pollution and lowering usage costs. In the future, with the continuous development of agricultural technology and the increasing environmental protection requirements of society, new pyrazole chelating inhibitors are expected to play a more important role in agricultural production.

[0027] Example 1

[0028] (I) Preparation method

[0029] Put 0.0248 g (0.2 mmol) of CuCl 2· 2H2O and 0.0700 g (0.4 mmol) of 3,5-dimethyl-4-bromopyrazole into a 50 mL conical flask respectively, add 5 mL of absolute ethanol and 10 mL of water to completely dissolve CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole; after sealing and puncturing the holes, let it stand at room temperature for about 1 day to obtain blue block crystals. Wash, filter and dry the block crystals to obtain a bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor with a yield of 98%.

[0030] (II) Detection

[0031] Use graphite monochromatized Mo Kα radiation as the diffraction light source on a Bruker D8 X-ray diffractometer to collect the diffraction intensity data of single crystals. Take the prepared bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor, the data obtained by SC-XRD, and further obtain its structure diagram as Figure 1 shown. Its crystal form belongs to the monoclinic system, and the space group is P 21 / c. In an asymmetric unit, the central ion copper (II) has a tetrahedral geometric configuration and chelates and coordinates with 2 nitrogen atoms of 2 3,5-dimethyl-4-bromopyrazole ligands, and forms a bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor through copper chloride connection, effectively enhancing its stability and endowing it with the dual inhibition functions of urease and nitrifying bacteria. Its crystallographic parameters are shown in Table 1.

[0032] Perform powder diffraction experiments on the crystals using a Bruker D8 Advance X-ray powder diffractometer. Use graphite monochromatized CuKα radiation, wavelength solid detector, step size 0.02°, step time 0.1 sec, scanning range 5° ≤ 2θ ≤ 45°. The powder X-ray diffraction curve (Experimental) of the prepared bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor matches the simulated curve of single crystal data( Figure 2 ).

[0033] Table 1 Crystallographic data table of bifunctional pyrazole-based inhibitors

[0034]

[0035] Example 2

[0036] Put 0.0248 g (0.2 mmol) of CuCl 2· 2H2O and 0.1050 g (0.6 mmol) of 3,5-dimethyl-4-bromopyrazole into a 50 mL conical flask respectively, add 5 mL of absolute ethanol and 10 mL of water to completely dissolve CuCl 2·2H2O and 3,5-dimethyl-4-bromopyrazole were completely dissolved; after sealing and puncturing holes, it was left standing at room temperature for about 1 day to obtain blue blocky crystals. The blocky crystals were washed, filtered, and dried to obtain a bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor with a yield of 93%.

[0037] Example 3

[0038] 0.0248 g (0.2 mmol) of CuCl 2· 2H2O and 0.0350 g (0.2 mmol) of 3,5-dimethyl-4-bromopyrazole were respectively placed into a 50 mL conical flask, and 5 mL of absolute ethanol and 10 mL of water were added to completely dissolve CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole; after sealing and puncturing holes, it was left standing at room temperature for about 1 day to obtain blue blocky crystals. The blocky crystals were washed, filtered, and dried to obtain a bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor with a yield of 85%.

[0039] Example 4

[0040] 0.0248 g (0.2 mmol) of CuCl 2· 2H2O and 0.0700 g (0.4 mmol) of 3,5-dimethyl-4-bromopyrazole were respectively placed into a 50 mL conical flask, and 5 mL of absolute ethanol and 15 mL of water were added to completely dissolve CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole; after sealing and puncturing holes, it was left standing at room temperature for about 1 day to obtain blue blocky crystals. The blocky crystals were washed, filtered, and dried to obtain a bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor with a yield of 68%.

[0041] Example 5

[0042] 0.0248 g (0.2 mmol) of CuCl 2· 2H2O and 0.0700 g (0.4 mmol) of 3,5-dimethyl-4-bromopyrazole were respectively placed into a 50 mL conical flask, and 5 mL of absolute ethanol and 20 mL of water were added to completely dissolve CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole; after sealing and puncturing holes, it was left standing at room temperature for about 1 day to obtain blue blocky crystals. The blocky crystals were washed, filtered, and dried to obtain a bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor with a yield of 65%.

[0043] Example 6

[0044] 0.0248 g (0.2 mmol) of CuCl 2·2H2O and 0.0700 g (0.4 mmol) of 3,5-dimethyl-4-bromopyrazole were separately placed into a 50 mL conical flask, and 5 mL of absolute ethanol and 10 mL of water were added to dissolve CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole completely; after sealing and puncturing holes, it was left standing at room temperature for about 2 days to obtain blue block crystals. The block crystals were washed, filtered, and dried to obtain a bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor with a yield of 92%.

[0045] Example 7

[0046] 0.0248 g (0.2 mmol) of CuCl 2· 2H2O and 0.0700 g (0.4 mmol) of 3,5-dimethyl-4-bromopyrazole were separately placed into a 50 mL conical flask, and 5 mL of absolute ethanol and 10 mL of water were added to dissolve CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole completely; after sealing and puncturing holes, it was left standing at room temperature for about 3 days to obtain blue block crystals. The block crystals were washed, filtered, and dried to obtain a bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor with a yield of 93%.

[0047] Example 8

[0048] 1. The method for measuring the urease inhibitor activity is as follows:

[0049] Take 1 mL (10 KU / L) of urease and 1 mL of bifunctional pyrazole-based chelating nitrogen fertilizer inhibitors with different contents (contents are 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1.6 μM, 3.2 μM, 6.4 μM respectively, the samples are dissolved in DMSO, DMSO:H2O = 1:1), mix them evenly, pre-culture in a 37 °C constant temperature shaking incubator for 1 h, then add 8 mL of phosphate buffer solution with pH = 6.8 (containing 500 mM urea and 0.002% phenol red indicator). The pH range is 6.8 - 7.7. Measure its absorbance at 570 nm with an ultraviolet spectrometer every 1 h, and calculate the inhibition rate of different contents of coordination polymers on urease ( Figure 3 ). The test end point is determined by the phenol red indicator. When the solution changes from light yellow to red, stop the test. The improved Karber method is used for the calculation of IC 50 . The IC 50 of the bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor = 1.933 μM, which proves that this new type of bifunctional pyrazole-based chelating nitrogen fertilizer inhibitor can be used as a urease inhibitor, its half-inhibition concentration is relatively low, and the dosage of the additive is small.

[0050] 2. The method for measuring the nitrification inhibition activity is as follows:

[0051] Weigh 0 g (control), 0.003 g, 0.005 g, 0.007 g, and 0.010 g of the bifunctional pyrazole chelated nitrogen fertilizer inhibitor prepared in Example 1 respectively, and place them in 500 mL conical flasks. Add 10.00 g of air-dried soil, 0.10 g of urea, and 100 mL of phosphate buffer solution to each flask. Put the conical flasks into a constant temperature incubation shaker (180 revolutions per minute) and shake for 48 h, then filter, and measure the mass fraction ω1 of nitrate nitrogen (including nitrite nitrogen) in the sample solution and the control sample solution respectively.

[0052] Calculation of nitrification inhibition rate: Calculate the nitrification inhibition rates of the bifunctional pyrazole chelated nitrogen fertilizer inhibitor with different addition amounts. The results are shown in Table 2.

[0053]

[0054] Where, dN: nitrification inhibition rate (%);

[0055] ω1—the mass fraction of nitrate nitrogen (including nitrite nitrogen) in the sample;

[0056] ω2—the mass fraction of nitrate nitrogen (including nitrite nitrogen) in the control sample, ω2 = 978.69.

[0057] Table 2

[0058]

[0059] As can be seen from Table 2, when the bifunctional pyrazole chelated nitrogen fertilizer inhibitor is used as a nitrification inhibitor, its nitrification inhibition rate is greater than 12%. When the addition amount gradually increases, the nitrification inhibition rate gradually increases. When the addition amount is 0.010 g, the nitrification inhibition rate reaches 18.44%. Therefore, its inhibitory effect on nitrifying bacteria is obvious. To sum up, the present invention chelates and coordinates 3,5-dimethyl-4-bromopyrazole as a ligand with copper chloride dihydrate to prepare a bifunctional pyrazole chelated nitrogen fertilizer inhibitor, which has a small addition amount, a high inhibition rate, a low dosage, low volatility, good stability, and inhibitory functions on both urease and nitrifying bacteria. It can be widely used as a urease and nitrification dual-functional inhibitor in the fertilizer urea. Considering the cost factor comprehensively, its optimal addition amount is 2‰.

[0060] The above has described the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge scope of those of ordinary skill in the art.

Claims

1. A method for preparing a bifunctional pyrazole chelated nitrogen fertilizer inhibitor, characterized in that: The steps include: 1) CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole are placed in a container according to a certain molar ratio; 2) Add anhydrous ethanol and water to the container in a certain volume ratio to completely dissolve CuCl 2· 2H2O and 3,5-dimethyl-4-bromopyrazole; 3) After sealing and piercing the container, the container was left to stand at room temperature for 1-3 days to obtain blue block crystals; 4) washing, filtering and drying the blue block crystals to obtain a bifunctional pyrazole chelated nitrogen fertilizer inhibitor.

2. The method for preparing the bifunctional pyrazole chelated nitrogen fertilizer inhibitor according to claim 1, characterized in that: In the step 1), CuCl 2· The molar ratio of 2H2O to 3,5-dimethyl-4-bromopyrazole is 1:1-3.

3. The method for preparing the bifunctional pyrazole chelated nitrogen fertilizer inhibitor according to claim 1, characterized in that: In the step 2), the volume ratio of anhydrous ethanol to water is 1:1-3.

4. A bifunctional pyrazole chelated nitrogen fertilizer inhibitor, characterized in that: It is prepared based on the method described in claims 1 to 3.

5. The bifunctional pyrazole chelated nitrogen fertilizer inhibitor according to claim 4, characterized in that: The chemical formula is C 10 H 14 Br2Cl2CuN4, the structural formula is:

6. The bifunctional pyrazole chelated nitrogen fertilizer inhibitor according to claim 4, characterized in that: The bifunctional pyrazole chelated nitrogen fertilizer inhibitor has a monoclinic crystal structure and a space group of P 21 / c.

7. The use of the bifunctional pyrazole chelated nitrogen fertilizer inhibitor according to claim 4, characterized in that: Used in fertilizers as urease and nitrifying bacteria inhibitors.

8. The use of the bifunctional pyrazole chelated nitrogen fertilizer inhibitor according to claim 7, characterized in that: The fertilizer is nitrogen fertilizer.

9. The use of the bifunctional pyrazole chelated nitrogen fertilizer inhibitor according to claim 8, characterized in that: The nitrogen fertilizer is urea.

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