Cu (II)-containing 1, 3-dimethyl pyrazole compound as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fertilizer synergists, and particularly provides a Cu (II)-containing 1, 3-dimethyl pyrazole compound and a preparation method and application thereof.The preparation method comprises the steps that CuCl2. 2H2O and 1, 3-dimethyl pyrazole are placed in a container, and absolute methanol and dichloromethane are added for dissolution; and then sealing the container, pricking holes, standing at room temperature for 2-4 days to obtain black blocky crystals, washing, filtering and drying to obtain the Cu (II)-containing 1, 3-dimethyl pyrazole compound. The Cu (II)-containing 1, 3-dimethyl pyrazole compound prepared by the invention can be used as a urease and nitrification inhibitor, has a relatively high inhibition rate on the activity of soil urease and nitrifying bacteria, and can greatly reduce nitrogen loss in agricultural production activities, improve the utilization rate of nitrogen fertilizer and reduce environmental pollution.

Description

Technical Field

[0001] The invention relates to the technical field of fertilizer synergists, and in particular provides a 1,3-dimethylpyrazole compound containing Cu (II) and a preparation method and application thereof. Background Art

[0002] 1,3-Dimethylpyrazole is a derivative of pyrazole and has significant nitration inhibitory activity. In addition, transition metals show important biological activities in many biochemical processes. Commonly used transition metals include copper, nickel, cobalt, zinc, etc. At the same time, the complexes formed with various metal ions have been shown to have significant inhibitory activity against various enzymes, among which copper ions have been shown to have good urease inhibitory ability.

[0003] As the population grows, excessive amounts of nitrogen fertilizers are applied to farmland to meet the growing demand for food, and almost 50% of the nitrogen input is lost to the atmosphere or seeps into groundwater. Ammonia (NH3) volatilization is considered to be one of the main gaseous nitrogen loss processes. NH3 is not only a key gas involved in the formation of particulate matter (PM2.5), but also a secondary source of indirect nitrous oxide (N2O) emissions. It also participates in the acidification and eutrophication of ecosystems through dry and wet deposition in the atmosphere, causing extremely serious ecological damage.

[0004] Therefore, it is crucial to develop an inhibitor of urease and nitrification. Metallic copper itself has an inhibitory effect on urease, and the complex containing Cu (II) has a good effect on urease inhibition. The active site of urease is characterized by the presence of a spiral flap at its entrance, which is believed to regulate the access of the substrate to the active site of the enzyme. Among them, copper ions can not only irreversibly occupy the binding site that should belong to nickel, causing irreversible inhibition of urease activity, but also block urea from entering its active site. By adding copper complexes to urea, the conversion of nitrogen fertilizer to ammonium nitrogen can be slowed down and the retention time of urea in the soil can be prolonged. In order to inhibit the conversion of nitrogen fertilizer for a longer time and improve the utilization efficiency, the method of adding urease inhibitors and nitrification inhibitors at the same time is adopted in production practice to inhibit the process of urea hydrolysis into ammonium nitrogen and the process of ammonium nitrogen oxidation into nitrate nitrogen. However, the addition of two inhibitors increases the cost of fertilizer production, which is not conducive to promotion and application.

[0005] Based on the above background, the present invention chooses to modify 1,3-dimethylpyrazole, uses 1,3-dimethylpyrazole as a ligand, and prepares a new type of Cu (II)-containing 1,3-dimethylpyrazole compound through a solvent volatilization method. The novel 1,3-dimethylpyrazole compound can inhibit urease and nitrifying bacteria at the same time and is a bifunctional inhibitor, which provides a new research direction for the green and healthy development of agriculture. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a 1,3-dimethylpyrazole compound containing Cu (II), a preparation method and an application thereof. 1,3-dimethylpyrazole is used as an organic ligand and Cu is used as a coordination center metal ion. The 1,3-dimethylpyrazole compound containing Cu (II) is synthesized by a solution volatilization method at a certain ratio.

[0007] The present invention is implemented by providing a preparation method of a 1,3-dimethylpyrazole compound containing Cu (II), comprising the following steps: placing CuCl2·2H2O and 1,3-dimethylpyrazole in a container, adding anhydrous methanol and dichloromethane to dissolve them; then sealing the container and piercing it, leaving it to stand at room temperature for 2-4 days to obtain black block crystals, and washing, filtering and drying to obtain the 1,3-dimethylpyrazole compound containing Cu (II).

[0008] Preferably, in molar ratio, CuCl2·2H2O:1,3-dimethylpyrazole=1:1.

[0009] Preferably, by volume ratio, dichloromethane:anhydrous methanol=1:2.

[0010] Provided is a 1,3-dimethylpyrazole compound containing Cu (II), which is prepared according to the above-mentioned preparation method of the 1,3-dimethylpyrazole compound containing Cu (II).

[0011] Preferably, the crystal form of the Cu(II)-containing 1,3-dimethylpyrazole compound belongs to the monoclinic system, and the space group is C2 / c.

[0012] Preferably, in the 1,3-dimethylpyrazole compound containing Cu (II), the coordination mode of the central ion copper (II) is a tetracoordinate structure. In one symmetric unit, the central ion copper (II) connects two identical nitrogen atoms and two chloride ions in 1,3-dimethylpyrazole to form a symmetrical tetrahedral configuration. The bond length of Cu-Cl is 2.263Å, the bond length of Cu-N is 1.975Å, the bond angle of Cl-Cu-Cl is 177.05°, and the bond angle of N-Cu-N is 178.5°.

[0013] Provided is an application of a 1,3-dimethylpyrazole compound containing Cu (II), which is used as a urease and nitrification inhibitor in fertilizers.

[0014] Preferably, in the above application, the fertilizer is nitrogen fertilizer.

[0015] Preferably, in the above application, the fertilizer is urea.

[0016] Compared with the prior art, the advantages of the present invention are: The 1,3-dimethylpyrazole compound containing Cu (II) prepared by the present invention has a good inhibitory effect on soil urease and nitrifying bacteria, can effectively delay the conversion of urea nitrogen to ammonium nitrogen, and at the same time delay the conversion of ammonium nitrogen to nitrate nitrogen, so that nitrogen can be retained in the soil for a longer time in a form that is more easily utilized by crops, and can effectively extend the fertilizer effect period of nitrogen fertilizer. In addition, the preparation method is simple, and the solvents used are only anhydrous methanol and dichloromethane. The preparation process does not require energy consumption, does not produce secondary pollution, and has a good application prospect. The 1,3-dimethylpyrazole compound containing Cu (II) prepared by the present invention is a dual-function inhibitor with the advantages of high inhibition rate, low dosage, good stability, not easy to be leached with water, low toxicity, and little impact on the environment. It can be used as a new type of fertilizer additive. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Figure 1 This is the single crystal thermal ellipsoid diagram of the target product prepared in Example 1.

[0018] Figure 2 The figure is a comparison between the powder X-ray diffraction pattern of the target product obtained in Example 1 and the single crystal data simulation pattern.

[0019] Figure 3 This is a graph showing the inhibition of urease by different concentrations of the target product prepared in Example 1. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying 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.

[0021] Example 1

[0022] 1. Preparation method 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.0182 g (0.2 mmol) of 1,3-dimethylpyrazole were placed in 50 ml conical flasks respectively, and 6 ml of anhydrous methanol and 3 ml of dichloromethane were added to completely dissolve them. After sealing and puncturing, the flask was left to stand at room temperature for about 3 days to obtain black block crystals. The block crystals were washed, filtered and dried to obtain 1,3-dimethylpyrazole compound containing Cu (II) with a yield of 95%.

[0023] 2. Testing The single crystal diffraction intensity data was collected on a Bruker D8-ray diffractometer using graphite monochromatized Mo Kα (λ=0.71073Å) radiation as the diffraction light source. The prepared 1,3-dimethylpyrazole compound containing Cu (II) was obtained by SC-XRD, and its structure was further obtained as shown in the figure Figure 1 As shown. Its crystal form belongs to the monoclinic system, and the space group is C2 / c. In an independent unit, the central ion copper (II) has a tetrahedral geometry and is coordinated with two nitrogen atoms of two 1,3-dimethylpyrazole ligand donor atoms. The central ion Cu (II) connects two identical nitrogen atoms in 1,3-dimethylpyrazole and two chloride ions to form a symmetrical square pyramid configuration. The bond length of Cu-Cl is 2.263Å, the bond length of Cu-N is 1.975Å, the bond angle of Cl-Cu-Cl is 177.05°, and the bond angle of N-Cu-N is 178.5°. Its crystallographic parameters are shown in Table 1.

[0024] The powder diffraction experiment of the crystal was carried out using a Bruker D8 Advance X-ray powder diffractometer. Graphite monochromatized CuKα radiation was used, wavelength λ=1.54056Å, solid detector, step length 0.01°, step time 0.3sec, scanning range 5°≤2θ≤45°. The obtained powder X-ray diffraction pattern of the 1,3-dimethylpyrazole compound containing Cu (II) matches the single crystal data simulation pattern ( Figure 2 ).

[0025] Table 1

[0026] Example 2

[0027] 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.0182 g (0.2 mmol) of 1,3-dimethylpyrazole were placed in 50 ml conical flasks respectively, and 6 ml of anhydrous methanol and 3 ml of dichloromethane were added to completely dissolve them. After sealing and puncturing, the flask was left to stand at room temperature for about 5 days to obtain black block crystals. The block crystals were washed, filtered and dried to obtain 1,3-dimethylpyrazole compound containing Cu (II) with a yield of 93.7%.

[0028] Example 3

[0029] 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.0182 g (0.2 mmol) of 1,3-dimethylpyrazole were placed in 50 ml conical flasks respectively, and 12 ml of anhydrous methanol and 6 ml of dichloromethane were added to completely dissolve them. After sealing and puncturing, the flask was left to stand at room temperature for about 4 days to obtain black block crystals. The block crystals were washed, filtered and dried to obtain 1,3-dimethylpyrazole compound containing Cu (II) with a yield of 91.3%.

[0030] Example 4

[0031] 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.0182 g (0.2 mmol) of 1,3-dimethylpyrazole were placed in 50 ml conical flasks respectively, and 4 ml of anhydrous methanol and 2 ml of dichloromethane were added to completely dissolve them. After sealing and puncturing, the flask was left to stand at room temperature for about 3 days to obtain black block crystals. The block crystals were washed, filtered and dried to obtain 1,3-dimethylpyrazole compound containing Cu (II) with a yield of 85.6%.

[0032] Example 5

[0033] 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.0182 g (0.2 mmol) of 1,3-dimethylpyrazole were placed in 50 ml conical flasks respectively, and 6 ml of anhydrous methanol and 3 ml of dichloromethane were added to completely dissolve them. After sealing and puncturing, the flask was left to stand at room temperature for about 2 days to obtain black block crystals. The block crystals were washed, filtered and dried to obtain 1,3-dimethylpyrazole compound containing Cu (II) with a yield of 68.1%.

[0034] Example 6

[0035] 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.0182 g (0.2 mmol) of 1,3-dimethylpyrazole were placed in 50 ml conical flasks respectively, and 10 ml of anhydrous methanol and 5 ml of dichloromethane were added to completely dissolve them. After sealing and puncturing, the flask was left to stand at room temperature for about 4 days to obtain black block crystals. The block crystals were washed, filtered and dried to obtain 1,3-dimethylpyrazole compound containing Cu (II) with a yield of 77.4%.

[0036] Example 7

[0037] 1. The method for determining the activity of urease inhibitors is as follows: The jack bean urease used in the test is commercially available. After grinding the sample to be tested into powder, weigh a certain mass of the sample and dissolve it with DMSO solution (DMSO:H2O=1:1) and make up the volume to obtain sample solutions of different concentrations. Subsequently, 4mL of urease solution (10KU / L) and 4mL of sample solutions of different concentrations were taken and mixed evenly, and then pre-incubated at 37°C for 1h. After that, 32mL of pH=6.8 (containing 500Mm / L urea and 0.002% phenol red indicator) phosphate buffer was added thereto. The pH range was 6.8-7.7, and the absorbance was measured at 570nm with an ultraviolet spectrometer at intervals of 1h. The endpoint of the test is determined by the phenol red indicator. The test is stopped when the solution changes from light orange-yellow to purple-red. The results are shown in Figure 3 .

[0038] IC 50 Calculation: Modified Koch method: lgIC 50 =Xm-I(P-(3-Pm-Pn) / 4), where Xm: lg maximum dose, I: lg (maximum dose / adjacent dose), P: sum of positive reaction rates, Pm: maximum positive reaction rate, Pn: minimum positive reaction rate. IC 50 =0.68±0.01μM / L, it can be seen that when the half-inhibitory concentration of this Cu (II)-containing 1,3-dimethylpyrazole compound as a urease inhibitor is low, the amount of the additive is small. Therefore, it can be concluded that the Cu (II)-containing 1,3-dimethylpyrazole compound of the present invention can be used as a urease inhibitor in fertilizer urea.

[0039] The method for determining the nitrification inhibition activity is as follows: 0 g (control), 0.003 g, 0.005 g, 0.007 g, and 0.010 g of the 1,3-dimethylpyrazole compound containing Cu (II) prepared in Example 1 were weighed respectively and placed in 500 mL conical flasks, 50.00 g of air-dried soil, 0.50 g of urea, and 100 mL of phosphate buffer were added to each flask. The conical flasks were simultaneously placed in a constant temperature incubation oscillator (180 rpm) and oscillated for 48 hours. After filtering, the mass fraction ω1 of nitrate nitrogen (including nitrite nitrogen) in the test sample and control sample solutions was determined respectively.

[0040] Calculation of nitrification inhibition rate: The nitrification inhibition rate of different added amounts of binuclear ligand was calculated, and the results are shown in Table 2.

[0041]

[0042] in, dN : Nitrification inhibition rate (%); ω1—mass fraction of nitrate nitrogen (including nitrite nitrogen) in the sample; ω2—mass fraction of nitrate nitrogen (including nitrite nitrogen) in the control sample, ω2=962.4.

[0043] Table 2

[0044] As can be seen from Table 2, 1,3-dimethylpyrazole compounds containing Cu (II) can be used as nitrification inhibitors, and their nitrification inhibition rate increases with increasing dosage. However, when the addition amount is greater than 0.003 g, the nitrification inhibition rate changes to 10.14, and considering the cost factor, 3‰ is the optimal addition amount. In summary, the present invention can be used as a dual-function inhibitor of urease and nitrification in fertilizer urea.

[0045] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing a 1,3-dimethylpyrazole compound containing Cu (II), characterized in that: The method comprises the following steps: placing CuCl2·2H2O and 1,3-dimethylpyrazole in a container, adding anhydrous methanol and dichloromethane to dissolve the mixture; then sealing the container, piercing the container, and standing the container at room temperature for 2-4 days to obtain black block crystals, and washing, filtering and drying the container to obtain a 1,3-dimethylpyrazole compound containing Cu (II).

2. The method for preparing a 1,3-dimethylpyrazole compound containing Cu (II) according to claim 1, characterized in that: In molar ratio, CuCl2·2H2O:1,3-dimethylpyrazole=1:

1.

3. The method for preparing a 1,3-dimethylpyrazole compound containing Cu (II) according to claim 1, characterized in that: By volume ratio, dichloromethane: anhydrous methanol = 1:

2.

4. A 1,3-dimethylpyrazole compound containing Cu(II), characterized in that: The compound is prepared according to the method for preparing a 1,3-dimethylpyrazole compound containing Cu (II) according to any one of claims 1 to 3.

5. The 1,3-dimethylpyrazole compound containing Cu (II) according to claim 4, characterized in that: The crystal form of the Cu(II)-containing 1,3-dimethylpyrazole compound belongs to the monoclinic system, and the space group is C2 / c.

6. The 1,3-dimethylpyrazole compound containing Cu (II) according to claim 4, characterized in that: In the 1,3-dimethylpyrazole compound containing Cu (II), the coordination mode of the central ion copper (II) is a tetracoordinate structure. In one symmetric unit, the central ion copper (II) connects two identical nitrogen atoms in 1,3-dimethylpyrazole and two chloride ions to form a symmetrical tetrahedral configuration. The bond length of Cu-Cl is 2.263Å, the bond length of Cu-N is 1.975Å, the bond angle of Cl-Cu-Cl is 177.05°, and the bond angle of N-Cu-N is 178.5°.

7. An application of a 1,3-dimethylpyrazole compound containing Cu (II), characterized in that: Used in fertilizers as urease and nitrification inhibitor.

8. The use of the 1,3-dimethylpyrazole compound containing Cu (II) according to claim 7, characterized in that: The fertilizer is nitrogen fertilizer.

9. The use of the 1,3-dimethylpyrazole compound containing Cu (II) according to claim 8, characterized in that: The fertilizer is urea.

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