A chloro-bridged pyrazole compound, its preparation method and application

Abstract

The present invention discloses a chloro-bridged pyrazole compound, its preparation method and application, which relates to the technical field of pyrazole derivative research. The pyrazole compound of the present invention is a product obtained by bridging 3-methylpyrazole through the chlorine atom in copper chloride by the solvent evaporation method. The present invention bridges 3-methylpyrazole through the chlorine atom in copper chloride by the solvent evaporation method, increases the stability of 3-methylpyrazole and further optimizes and improves its properties, so that 3-methylpyrazole which only has the function of nitrification inhibitor also has the function of inhibiting the activity of urease, enabling nitrogen to be retained in the soil in the form of ammonium nitrogen which is more conducive to crop absorption for a longer time, and can extend the fertilizer efficiency period of nitrogen fertilizer; the chloro-bridged pyrazole compound provided by the present invention can be used as both urease and nitrification inhibitors at the same time, thereby greatly reducing its addition amount in fertilizers and reducing the production cost of new fertilizers.

Description

Technical Field

[0001] The present invention relates to the technical field of pyrazole derivative research, and specifically relates to a chlorine-bridged pyrazole compound, a preparation method thereof, and an application thereof. Background Art

[0002] Urea is the most widely used nitrogen fertilizer in current agricultural production, accounting for about 2 / 3 of the total nitrogen fertilizer application. In order to inhibit the conversion of urea for a longer time and improve the utilization efficiency, in production practice, the method of adding urease inhibitors and nitrification inhibitors simultaneously is adopted to inhibit the process of urea hydrolysis into ammonium nitrogen and the oxidation process of ammonium nitrogen. However, the addition of the two inhibitors increases the production cost of new fertilizers and limits their application in the production field.

[0003] 3-Methylpyrazole is a pyrazole derivative with relatively low price, which can effectively inhibit the oxidation of ammonium ions in the soil. Therefore, it can be considered as a nitrification inhibitor and applied to agricultural fertilizers to improve the utilization rate of nitrogen elements in fertilizers and reduce fertilizer efficiency loss. However, 3-methylpyrazole has instabilities such as low melting point, easy volatilization, strong irritation, flammability, and easy decomposition at high temperature, resulting in large losses when it is added to fertilizers by itself. Its use as a nitrification inhibitor still cannot solve the technical problem of high production cost of new fertilizers. Summary of the Invention

[0004] The present invention provides a chlorine-bridged pyrazole compound to solve the technical problem of large losses when 3-methylpyrazole with low melting point, easy volatilization, strong irritation, flammability, and easy decomposition at high temperature is added to fertilizers by itself, and further optimizes and improves its properties, so that 3-methylpyrazole with only the function of nitrification inhibitor also has the function of inhibiting urease activity, and has the outstanding advantages of dual inhibition functions of urease and nitrification, which can greatly reduce the addition amount of inhibitors in fertilizers, thereby reducing the use cost; in addition, the present invention also provides a specific preparation method and application of high-stability 3-methylpyrazole.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A chlorine-bridged pyrazole compound, wherein the pyrazole compound is a product obtained by bridging 3-methylpyrazole through chlorine atoms in copper chloride by the solvent evaporation method with 3-methylpyrazole as the base.

[0007] Preferably, the molar ratio of copper chloride to 3-methylpyrazole is 1:1 to 2.

[0008] Preferably, the solvent used in the solvent evaporation method is a mixed solvent of absolute ethanol and dichloromethane, wherein the volume ratio of absolute ethanol to dichloromethane is 1:2 to 4.

[0009] The preparation method of the chlorine-bridged pyrazole compound comprises the following steps:

[0010] (1) Place CuCl2 and 3-methylpyrazole in a 50 mL conical flask, and add a solvent for dissolution;

[0011] (2) After sealing and puncturing the container, let it stand at room temperature for 2 to 4 days to obtain blue blocky crystals, and then obtain the target pyrazole compound product through washing, filtration, and drying.

[0012] The chlorine-bridged pyrazole compound is applied as a urease and / or nitrification inhibitor during the preparation and / or use of chemical fertilizers.

[0013] Further, the chemical fertilizer is a nitrogen-containing chemical fertilizer.

[0014] Furthermore, the nitrogen fertilizer is urea.

[0015] In summary, compared with the prior art, the present invention has the following advantages and beneficial effects:

[0016] 1. The present invention uses the solvent evaporation method to bridge 3-methylpyrazole through the chlorine atoms in copper chloride, increasing the stability of 3-methylpyrazole and further optimizing and improving its properties, so that 3-methylpyrazole, which only has the function of a nitrification inhibitor, also has the function of inhibiting urease activity, with the prominent advantages of dual inhibition of urease and nitrification. While delaying the conversion of urea nitrogen to ammonium nitrogen, it also delays the conversion of ammonium nitrogen to nitrate nitrogen, enabling nitrogen to be retained in the soil in the form of ammonium nitrogen, which is more conducive to crop absorption, for a longer time, and can extend the fertilizer efficiency period of nitrogen fertilizers; the chlorine-bridged pyrazole compound provided by the present invention can be used as a dual inhibitor of urease and nitrification, thereby greatly reducing its addition amount in fertilizers and reducing the production cost of new fertilizers;

[0017] 2. The preparation method of the present invention is simple, and the solvents used are only ethanol and dichloromethane. The preparation process does not require energy consumption and does not produce secondary pollution, having good application prospects;

[0018] 3. The chlorine-bridged 3-methylpyrazole compound prepared by the present invention is a dual-functional inhibitor with high inhibition rate, low dosage, good stability, not easily leached with water, low toxicity, and little impact on the environment, so it can be applied in fertilizers. Description of the Drawings

[0019] Figure 1 It is the single-crystal thermal ellipsoid diagram of the target product prepared in Example 1.

[0020] Figure 2 It is the comparison between the powder X-ray diffraction pattern of the target product prepared in Example 1 and the simulated diagram of single-crystal data.

[0021] Figure 3 It is the inhibition graph of the target product prepared in Example 1 with different concentrations on urease. Detailed implementation manners

[0022] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with each embodiment. 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, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0023] The special term "embodiment" here, any embodiment described as "exemplary" does not have to be interpreted as superior to or better than other embodiments. For the performance index test in the embodiments of this method, unless otherwise specified, the conventional test methods in the art are adopted. The terms described in the present invention are only used to describe specific embodiments and are not used to limit the content disclosed in the present invention.

[0024] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the technical field to which the present invention belongs; other raw materials, reagents, test methods and technical means not specifically noted in the present invention refer to the raw materials and reagents commonly used by those of ordinary skill in the art, as well as the experimental methods and technical means commonly adopted.

[0025] Example 1

[0026] This example provides a chloro-bridged 3-methylpyrazole compound, and its preparation process is as follows: 0.0269 g (0.2 mmol) of CuCl2 and 0.0164 g (0.2 mmol) of 3-methylpyrazole are respectively placed in a 50 ml conical flask, and 5 mL of absolute ethanol and 10 mL of dichloromethane are added to completely dissolve them; after sealing and puncturing holes, it is left standing at room temperature for about 2 days to obtain blue blocky crystals. The blocky crystals are washed, filtered and dried to obtain the chloro-bridged 3-methylpyrazole compound, and the yield is 98%.

[0027] On a Bruker D8-ray diffractometer, graphite monochromatization radiation is used as the diffraction light source to collect the diffraction intensity data of the single crystal. Take the data of the chloro-bridged 3-methylpyrazole compound prepared in this example, and further obtain its structural diagram as Figure 1As shown, it can be seen that its crystal form belongs to the monoclinic system, and the space group is P21 / n. In an asymmetric unit, the central ion copper (II) has a tetrahedral geometry and coordinates with the two nitrogen atoms of the two 3-methylpyrazole ligand donor atoms, linking the two 3-methylpyrazoles into a block (∠N-Cu-Cl=89.05°-95.06°). The blocks are linked by chlorine atom bridges to form a 0D structure (∠Cu-Cl-Cu=88.63°), thereby increasing the stability of the 3-methylpyrazole structure. Its crystallographic parameters are shown in Table 1.

[0028] Table 1

[0029]

[0030]

[0031] The powder diffraction experiment of the crystals was carried out using a Bruker D8 Advance X-ray powder diffractometer. Graphite monochromatized CuKα radiation was used, with a wavelength of Solid detector, step length 0.01°, step time 0.3 sec, scanning range 5°≤2θ≤45°. The powder X-ray diffraction pattern of the prepared chloro-bridged 3-methylpyrazole compound is basically consistent with the single crystal data simulation pattern ( Figure 2 ).

[0032] The activity of urease inhibitor was measured: 1 mL (10 KU / L) urease and 1 mL of coordination polymer samples with different contents (the samples were dissolved in DMSO, DMSO:H2O=1:1) were mixed evenly and pre-cultured in a 37°C constant temperature shaking incubator for 1 hour, and then 8 mL of pH=6.8 (containing 500 mM urea and 0.002% phenol red indicator) phosphate buffer was added thereto. The pH range of the buffer was 6.8-7.7. The absorbance was measured at 570 nm using an ultraviolet spectrometer at intervals of 1 hour. The endpoint of the test was determined by the phenol red indicator, and the test was stopped when the solution changed from light yellow to red. The results are as follows: Figure 3 IC was performed using the modified Koch method. 50 Calculation of chlorine-bridged 3-methylpyrazole compounds IC 50 =1.92±0.03 μM, which shows that this chloro-bridge-linked 3-methylpyrazole compound can be used as a urease inhibitor with a low half-inhibitory concentration and a small amount of additive.

[0033] Determination of nitrification inhibition activity: Weigh 0 g (control), 0.003 g, 0.005 g, 0.007 g, and 0.010 g of the chloro-bridged 3-methylpyrazole compound 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 shaking incubator (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.

[0034] Calculation of nitrification inhibition rate: Calculate the nitrification inhibition rates of the binuclear ligands with different addition amounts, and the results are shown in Table 2.

[0035]

[0036] Among them, dN: nitrification inhibition rate (%).

[0037] ω1—mass fraction of nitrate nitrogen (including nitrite nitrogen) in the sample.

[0038] ω2—mass fraction of nitrate nitrogen (including nitrite nitrogen) in the control sample, ω2 = 905.6.

[0039] Table 2 Mass fraction ω1 of nitrate nitrogen and nitrification inhibition rate dN in the sample solution and the control sample solution

[0040]

[0041]

[0042] As can be seen from Table 2, the chloro-bridged 3-methylpyrazole compound can be used as a nitrification inhibitor, and its nitrification inhibition rate is greater than 7%. When the addition amount gradually increases, the nitrification inhibition rate changes little. Considering the cost factor, the optimal addition amount is 4‰. To sum up, the present invention uses 3-methylpyrazole as a ligand, and through chloro-bridging, the stability of the 3-methylpyrazole compound can be effectively improved, and it can be used as a dual-functional inhibitor of urease and nitrification in the fertilizer urea.

[0043] Example 2

[0044] Compared with Example 1, this example discusses the influence of different solvent volume ratios on the product yield. The preparation process is as follows: Put 0.0269 g (0.2 mmol) of CuCl2 and 0.0164 g (0.2 mmol) of 3-methylpyrazole into a 50 ml conical flask respectively, add 5 mL of absolute ethanol and 15 mL of dichloromethane to dissolve them completely; after sealing and puncturing the holes, let it stand at room temperature for about 3 days to obtain blue blocky crystals. Wash, filter, and dry the blocky crystals to obtain the chloro-bridged 3-methylpyrazole compound, and the yield is 96%.

[0045] Example 3

[0046] Compared with Example 1, this example discusses the influence of different solvent volume ratios on the product yield. The preparation process is as follows: 0.0269 g (0.2 mmol) of CuCl2 and 0.0164 g (0.2 mmol) of 3-methylpyrazole are respectively placed into a 50 ml conical flask, and 5 mL of absolute ethanol and 20 mL of dichloromethane are added to completely dissolve them; after sealing and puncturing holes, it is left standing at room temperature for about 4 days to obtain blue block-shaped crystals. The block-shaped crystals are washed, filtered, and dried to obtain a chloro-bridged 3-methylpyrazole compound with a yield of 90%.

[0047] Example 4

[0048] Compared with Example 1, this example discusses the influence of different substrate molar ratios on the product yield. The preparation process is as follows: 0.0269 g (0.2 mmol) of CuCl2 and 0.0328 g (0.4 mmol) of 3-methylpyrazole are respectively placed into a 50 ml conical flask, and 5 mL of absolute ethanol and 10 mL of dichloromethane are added to completely dissolve them; after sealing and puncturing holes, it is left standing at room temperature for about 2 days to obtain blue block-shaped crystals. The block-shaped crystals are washed, filtered, and dried to obtain a chloro-bridged 3-methylpyrazole compound with a yield of 60%.

[0049] Example 5

[0050] Compared with Example 1, this example discusses the influence of different solvent volume ratios and different substrate molar ratios on the product yield. The preparation process is as follows: 0.0269 g (0.2 mmol) of CuCl2 and 0.0328 g (0.4 mmol) of 3-methylpyrazole are respectively placed into a 50 ml conical flask, and 5 mL of absolute ethanol and 15 mL of dichloromethane are added to completely dissolve them; after sealing and puncturing holes, it is left standing at room temperature for about 3 days to obtain blue block-shaped crystals. The block-shaped crystals are washed, filtered, and dried to obtain a chloro-bridged 3-methylpyrazole compound with a yield of 62%.

[0051] Example 6

[0052] Compared with Example 1, this example discusses the influence of different solvent volume ratios and different substrate molar ratios on the product yield. The preparation process is as follows: 0.0269 g (0.2 mmol) of CuCl2 and 0.0328 g (0.4 mmol) of 3-methylpyrazole are respectively placed into a 50 ml conical flask, and 5 mL of absolute ethanol and 20 mL of dichloromethane are added to completely dissolve them; after sealing and puncturing holes, it is left standing at room temperature for about 4 days to obtain blue block-shaped crystals. The block-shaped crystals are washed, filtered, and dried to obtain a chloro-bridged 3-methylpyrazole compound with a yield of 51%.

[0053] The above-described embodiments merely represent the specific implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application.

Claims

1. Use of a chlorine-bridged pyrazole compound as a dual inhibitor of urease and nitrification in chemical fertilizers, characterized in that, The chlorine-bridged pyrazole compound is a product obtained by using 3-methylpyrazole as a base and bridging 3-methylpyrazole through the chlorine atoms in copper chloride by the solvent evaporation method. The chemical formula of this product is C 16 H 24 Cl4Cu2N8, and the structural formula is shown in Formula 1; Among them, the molar ratio of the copper chloride to 3-methylpyrazole is 1:1; the solvent used in the solvent evaporation method is a mixed solvent of absolute ethanol and dichloromethane, wherein the volume ratio of absolute ethanol to dichloromethane is 1:

2. The preparation process includes the following steps: (1) Place CuCl2 and 3-methylpyrazole in a 50 mL conical flask, and add a solvent for dissolution; (2) After sealing and puncturing the container, let it stand at room temperature for 2 to 4 days to obtain blue blocky crystals, and then the target pyrazole compound product can be obtained through washing, filtration and drying.

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