Polymorphs of pyrazoxyfen, processes for their preparation and use thereof

Abstract

The present application relates to compound crystal form, specifically to a pyrazoxyfen polymorph and a preparation method and application thereof. The pyrazoxyfen polymorphs are all white powders, and microscopically, they have different molecular packing modes, can be classified into various crystal forms, and the X-ray powder diffraction patterns of the crystal forms are described in the specification. The present application discloses that each crystal form of pyrazoxyfen has excellent biological activity and solubility.

Description

Technical Field

[0001] The present invention relates to a compound crystal form, in particular to a polymorph of quinclorac-butyl and a preparation method and application thereof. Background Art

[0002] 4-HPPD is widely present in aerobic organisms, primarily involved in the metabolism of tyrosine. In plants, 4-HPPD reacts with p-hydroxyphenylpyruvate, a metabolite of tyrosine, to form homogentisate. Homogentisate is further converted into plastoquinone and tocopherol, hindering plant photosynthesis and causing plant albinism and death. Herbicides targeting 4-HPPD are highly effective, low toxic, environmentally friendly, and safe for subsequent crops. Therefore, 4-HPPD herbicides are a class of herbicides with significant research value and development prospects. Mesotrione is a well-known herbicide based on 4-HPPD. Three crystalline forms (Form I, Form II, and Form III) have been reported. Form I is relatively stable and suitable for production. However, during the actual production of Form I, Form II is often produced. Form II is a metastable, needle-shaped crystal that can clog filters, making filtration difficult. Furthermore, Form II is thermodynamically unstable, leading to instability during storage or in-field application. WO 2007 / 083242 and WO 2006 / 021743 disclose methods for selectively controlling the crystallization of either the thermodynamically stable Form I or the kinetically stable Form II of mesotrione from an aqueous solution of mesotrione. Furthermore, WO 2011016018A1 discloses Form III, which exhibits reduced phytotoxicity. Currently, mesotrione still suffers from instability, degrading at temperatures exceeding 60°C. Therefore, it should be stored away from heat and direct sunlight.

[0003] Meanwhile, pyraclostrobin (Formula I) is also a 4-HPPD herbicide. Its chemical name is 4-3-(3-chlorophenyl)-1,5-dimethyl-2,4-dioxo-1,2,3,4-tetrahydroquinazoline-6-carbonyl)-1,3-dimethylpyrazole-5-diethylcarbamate. It is a 4-HPPD herbicide independently developed in my country. Extensive experiments have shown that it has excellent control effects on grass weeds such as resistant barnyardgrass, Leptochloa crus-galli, Setaria viridis, and Digitaria sanguinalis. Currently, no crystalline form of this compound has been reported. The compound has poor water solubility (less than 1 ppm), and the dosage used for barnyardgrass control is relatively high (10-20 g / mu).

[0004] Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, an object of the present invention is to provide a polymorph of pyraclostrobin, which has a clear crystal form and number of crystal waters, exact main crystallographic parameters and atomic spatial positions; another object of the present invention is to provide a method for preparing the polymorph of pyraclostrobin; and a further object of the present invention is to provide the use of the polymorph of pyraclostrobin in the preparation of herbicides.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A polymorph of pyraclostrobin, wherein the polymorphs of pyraclostrobin are all white powders. Microscopically, they have different crystal stacking modes and can be divided into crystal form I, crystal form II, crystal form III, crystal form IV, crystal form V, crystal form VI, and crystal form VII. The X-ray powder diffraction patterns of each crystal form are as follows. The X-ray powder diffraction pattern of the crystal form I has a diffraction peak selected from the following 2θ values:

[0008] 10.5±0.2°, 11.7±0.2°, 12.6±0.2°, 13.7±0.2°, 21.0±0.2°, 21.7±0.2°, 24.0±0.2°; 12.2±0.2°, 16.3±0.2°, 21.6±0.2°, 23.5±0.2°, 13.7±0.2°, 24.0±0.2°, 30.9±0.2° ;9.3±0.2°, 11.4±0.2°, 16.3±0.2°, 19.9±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°;9.3±0.2°, 10.3±0.2°, 13.3±0.2°, 17.6±0.2°, 21.3±0.2°, 25.8±0.2°, 32.1±0.2°;

[0009] The X-ray powder diffraction pattern of the crystalline form II has diffraction peaks at the following 2θ values: 11.0±0.2°, 11.5±0.2°, 16.0±0.2°, 16.9±0.2°, 21.1±0.2°, 26.4±0.2°, 27.3±0.2°; 12.2±0.2°, 16.3±0.2°, 21.6±0.2°, 23.5±0.2°, 17.1±0.2°, 21. 1±0.2°, 30.9±0.2°; 9.3±0.2°, 11.4±0.2°, 16.3±0.2°, 19.9±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°; 9.3±0.2°, 10.3±0.2°, 11.8±0.2°, 17.6±0.2°, 21.3±0.2°, 25.8±0.2°, 32.1±0.2°;

[0010] The X-ray powder diffraction pattern of the crystalline form III is selected from the following 2θ values ​​with diffraction peaks:

[0011] 6.5±0.2°, 10.9±0.2°, 12.7±0.2°, 17.1±0.2°, 21.1±0.2°, 23.8±0.2°, 27.5±0.2°; 12.2±0.2°, 16.3±0.2°, 21.6±0.2°, 23.5±0.2°, 17.1±0.2°, 21.1±0.2°, 30.9±0.2° ;9.3±0.2°, 11.4±0.2°, 16.3±0.2°, 19.9±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°;9.3±0.2°, 10.3±0.2°, 11.8±0.2°, 17.6±0.2°, 21.3±0.2°, 25.8±0.2°, 32.1±0.2°;

[0012] The X-ray powder diffraction pattern of the crystalline form IV is selected from the following 2θ values ​​with diffraction peaks:

[0013] 6.5±0.2°, 11.6±0.2°, 13.1±0.2°, 15.4±0.2°, 16.0±0.2°, 21.4±0.2°, 25.4±0.2°; 9.3±0.2°, 20.3±0.2°, 21.4±0.2°, 15.4±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°; 9.3±0.2°, 11.6±0.2°, 13.3±0.2°, 17.6±0.2°, 21.6±0.2°, 21.6±0.2°, 25.8±0.2°;

[0014] The X-ray powder diffraction pattern of the crystalline form V has diffraction peaks selected from the following 2θ values:

[0015] 6.4±0.2°, 11.7±0.2°, 12.8±0.2°, 13.6±0.2°, 14.6±0.2°, 25.7±0.2°, 27.2±0.2°; 12.2±0.2°, 16.3±0.2°, 21.6±0.2°, 23.5±0.2°, 13.7±0.2°, 24.0±0.2°, 30.9±0.2° ;9.3±0.2°, 11.4±0.2°, 12.8±0.2°, 13.6±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°; 5.4±0.2°, 11.7±0.2°, 13.3±0.2°, 17.6±0.2°, 21.3±0.2°, 25.8±0.2°, 32.1±0.2°;

[0016] The crystal form VI is amorphous, and its X-ray powder diffraction pattern shows a steamed bun peak at (3-35°);

[0017] The X-ray powder diffraction pattern of the crystal form VII has diffraction peaks at 2θ values selected from:

[0018] 10.5±0.2°, 11.2±0.2°, 13.6±0.2°, 16.5±0.2°, 17.6±0.2°, 21.1±0.2°, 24.5±0.2°; 13.1±0.2°, 16.5±0.2°, 21.6±0.2°, 23.5±0.2°, 13.7±0.2°, 24.5±0.2°, 30.9±0.2°; 9.3±0.2°, 11.4±0.2°, 12.8±0.2°, 17.0±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°; 5.4±0.2°, 11.2±0.2°, 13.3±0.2°, 17.6±0.2°, 21.3±0.2°, 26.7±0.2°, 32.1±0.2°.

[0019] The specific structural formula of each crystal form of the pyrazolate is The crystal cell parameters of the crystal form I are as follows:

[0020]

[0021] Space group: P-1

[0022] The crystal cell parameters of the crystal form II are as follows

[0023]

[0024] Space group: P-1

[0025] The crystal cell parameters of the crystal form III are as follows

[0026]

[0027] Space group: P21 / n

[0028] The crystal cell parameters of the crystal form IV are as follows

[0029]

[0030] Space group: P-1

[0031] The crystal cell parameters of the crystal form VII (hydrate) are as follows

[0032]

[0033] Space group: P-1.

[0034] A method for preparing polymorphs of quinclorac-butyl comprises adding 50-1000 mg of quinclorac-butyl (compound of formula I) to 2 ml of solvent at 5-100° C., mixing, and drying to obtain corresponding crystalline forms of quinclorac-butyl; the solvent is one or more of methanol, ethyl acetate, acetonitrile, tetrahydrofuran, acetone, dioxane, chloroform, N,N-dimethylformamide, methyl tert-butyl ether, diethyl ether, n-hexane, cyclohexane, isopropyl alcohol, toluene, methyl oleate, and dichloromethane.

[0035] When the solvent is one or more of methanol, ethyl acetate, acetonitrile, tetrahydrofuran, acetone, dioxane, chloroform, and N,N-dimethylformamide, crystalline form I of quinoxaline can be obtained;

[0036] When the solvent is one or more of methyl tert-butyl ether, ethyl ether, n-hexane, cyclohexane, isopropanol, toluene, and methyl oleate, crystalline form II of pyraclostrobin can be obtained;

[0037] When the solvent is dichloromethane, pyraclostrobin in crystal form V can be obtained.

[0038] A method for preparing the polymorph of pyraclostrobin comprises adding a solvent to 500 mg of pyraclostrobin (compound of formula I) to completely dissolve it, filtering, stirring at room temperature, adding water to the solution until a solid precipitates, and then filtering and drying to obtain the crystalline form VII of pyraclostrobin.

[0039] The solvent is one or more of acetonitrile, butanone and chloroform.

[0040] A method for preparing a polymorph of quinclorac-butyl is disclosed, comprising heating quinclorac-butyl (compound of formula I) to 50-300° C., then cooling to below 200° C., and allowing the mixture to stand for crystallization to obtain the corresponding crystal form of quinclorac-butyl.

[0041] Generally speaking, a relatively fast heating rate (greater than 5°C / min (generally not more than 30°C / min)) will obtain Form III, and a relatively slow heating rate (5°C / min) generally obtains Form IV.

[0042] A method for preparing the polymorph of quinclorac-butyl is provided, wherein quinclorac-butyl (compound of formula I) is heated to 50-300° C., then cooled to room temperature, and allowed to stand to obtain the crystal form VI of quinclorac-butyl.

[0043] An application of the polymorphs of quinclorac-butyl, and an application of each crystal form of quinclorac-butyl in the preparation of herbicides.

[0044] The advantages of the present invention are:

[0045] The present invention provides seven polymorphs of pyraclostrobin (crystal form I, crystal form II, crystal form III, crystal form IV, crystal form V, crystal form VI, and crystal form VII (hydrate)). The preparation method of each crystal form is simple, and the obtained crystal forms, crystal form I, crystal form II, crystal form III, crystal form IV, and crystal form VII (hydrate), have clear crystal forms and the number of crystal waters, clear main crystallographic parameters, and exact atomic spatial positions, and are suitable for large-scale promotion and application.

[0046] The polymorphs of pyraclostrobin of the present invention have excellent biological activity. Compared with Form I, the solubility of the other forms is improved, thereby further enhancing their herbicidal activity. Among them, Form II and Form VII have more prominent herbicidal activity. At the same time, the obtained forms are suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The X-ray powder diffraction pattern (PXRD) of pyraclostrobin crystalline form I provided in an embodiment of the present invention.

[0048] Figure 2 This is a single crystal structure diagram of pyraclostrobin crystal form I provided in an embodiment of the present invention.

[0049] Figure 3 The differential scanning calorimetry (DSC) diagram of the pyraclostrobin crystal form I provided in an embodiment of the present invention is shown.

[0050] Figure 4 This is a thermogravimetric analysis (TG) diagram of pyraclostrobin Form I provided in an embodiment of the present invention.

[0051] Figure 5 The X-ray powder diffraction pattern (PXRD) of pyraclostrobin crystalline form II provided in an embodiment of the present invention.

[0052] Figure 6 This is a single crystal structure diagram of pyraclostrobin crystal form II provided in an embodiment of the present invention.

[0053] Figure 7 The differential scanning calorimetry (DSC) diagram of the pyraclostrobin crystal form II provided in an embodiment of the present invention is shown.

[0054] Figure 8 This is a thermogravimetric analysis (TG) diagram of pyraclostrobin crystalline form II provided in an embodiment of the present invention.

[0055] Figure 9 The X-ray powder diffraction pattern (PXRD) of pyraclostrobin crystalline form III provided in an embodiment of the present invention.

[0056] Figure 10 This is a single crystal structure diagram of pyraclostrobin crystal form III provided in an embodiment of the present invention.

[0057] Figure 11 The X-ray powder diffraction pattern (PXRD) of pyraclostrobin crystal form IV provided in an embodiment of the present invention.

[0058] Figure 12 This is a single crystal structure diagram of pyraclostrobin Form IV provided in an embodiment of the present invention.

[0059] Figure 13 This is the X-ray powder diffraction pattern (PXRD) of the pyraclostrobin crystal form V provided in an embodiment of the present invention.

[0060] Figure 14 The differential scanning calorimetry (DSC) diagram of the pyraclostrobin crystal form V provided in an embodiment of the present invention is shown.

[0061] Figure 15 This is a thermogravimetric analysis (TG) diagram of pyraclostrobin crystal form V provided in an embodiment of the present invention.

[0062] Figure 16 The X-ray powder diffraction pattern (PXRD) of pyraclostrobin crystal form VI provided in an embodiment of the present invention.

[0063] Figure 17 The differential scanning calorimetry (DSC) diagram of the pyraclostrobin crystal form provided in the embodiments of the present invention is shown.

[0064] Figure 18 The X-ray powder diffraction pattern (PXRD) of the pyraclostrobin crystal form VII (hydrate) provided in an embodiment of the present invention.

[0065] Figure 19 This is a single crystal structure diagram of the pyraclostrobin crystal form VII (hydrate) provided in an embodiment of the present invention.

[0066] Figure 20 The differential scanning calorimetry (DSC) diagram of the pyraclostrobin crystal form VII (hydrate) provided in an embodiment of the present invention.

[0067] Figure 21 This is a thermogravimetric analysis (TG) diagram of the pyraclostrobin crystal form VII (hydrate) provided in an embodiment of the present invention.

[0068] Figure 22 This is the X-ray powder diffraction pattern (PXRD) of the stability test of the pyraclostrobin crystal form I provided in the embodiment of the present invention at 50°C.

[0069] Figure 23 This is the X-ray powder diffraction pattern (PXRD) of the stability test of the pyraclostrobin crystal form II provided in the embodiment of the present invention at 50°C.

[0070] Figure 24 The X-ray powder diffraction pattern (PXRD) of the pyroquilon crystal form crystal form V provided by the embodiment of the present application in the 50℃ stability experiment.

[0071] Figure 25 The X-ray powder diffraction pattern (PXRD) of the pyroquilon crystal form crystal form VI provided by the embodiment of the present application in the 50℃ stability experiment.

[0072] Figure 26 The X-ray powder diffraction pattern (PXRD) of the pyroquilon crystal form crystal form VII provided by the embodiment of the present application in the 50℃ stability experiment.

[0073] Figure 27 The X-ray powder diffraction pattern (PXRD) of the pyroquilon crystal form crystal form I provided by the embodiment of the present application in the 25℃ water suspension stability experiment.

[0074] Figure 28 The X-ray powder diffraction pattern (PXRD) of the pyroquilon crystal form crystal form II provided by the embodiment of the present application in the 25℃ water suspension stability experiment.

[0075] Figure 29 The X-ray powder diffraction pattern (PXRD) of the pyroquilon crystal form crystal form V provided by the embodiment of the present application in the 25℃ water suspension stability experiment.

[0076] Figure 30 The X-ray powder diffraction pattern (PXRD) of the pyroquilon crystal form crystal form VI provided by the embodiment of the present application in the 25℃ water suspension stability experiment.

[0077] Figure 31 The X-ray powder diffraction pattern (PXRD) of the pyroquilon crystal form crystal form VII provided by the embodiment of the present application in the 25℃ water suspension stability experiment. DETAILED DESCRIPTION

[0078] The present application will be further described in the following examples. It should be correctly understood that the examples of the present application are only used to illustrate the present application, but not to limit the present application, so that the simple improvement of the present application under the premise of the method of the present application is within the scope of the present application.

[0079] Materials used in the experiment: the compound of formula I used can be prepared according to the preparation method described in the patent specification with the patent number ZL201910272386.4, or obtained by purchase; the other materials used in the experiment without the source and specification marked are commercially available analytical pure or chemical pure.

[0080] Example 1

[0081] Preparation of Form I:

[0082] Pyrazolate (compound of Formula I) 200 mg was added to 2 ml of acetonitrile at 5-100 °C, mixed well and dried to obtain the crystalline form of the compound of Formula I, i.e. Form I;

[0083] The yield of the above obtained Form I was 80% and the purity was 99% (PXRD spectrum confirmed the purity, Model of powder diffractometer and important parameters: Rigaku SmartLab, Cu-K target (tube voltage 40 kV, tube current 150 mA)) (see Figure 1-4 ).

[0084] The X-ray powder diffractogram of the Form I is selected from the group consisting of having diffraction peaks at 2Θ values of 10.5±0.2°, 11.7±0.2°, 12.6±0.2°, 13.7±0.2°, 21.0±0.2°, 21.7±0.2°, 24.0±0.2°;

[0085] 12.2±0.2°, 16.3±0.2°, 21.6±0.2°, 23.5±0.2°, 13.7±0.2°, 24.0±0.2°, 30.9±0.2°;

[0086] 9.3±0.2°, 11.4±0.2°, 16.3±0.2°, 19.9±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°;

[0087] 9.3±0.2°, 10.3±0.2°, 13.3±0.2°, 17.6±0.2°, 21.3±0.2°, 25.8±0.2°, 32.1±0.2°;

[0088] Cell parameters:

[0089]

[0090] Space group: P-1.

[0091] Example 2

[0092] Obtaining of Form II:

[0093] Pyrazolate (compound of Formula I) 200 mg was added to 2 ml of n-hexane at 5-100 °C, mixed well and dried to obtain the crystalline form of the compound of Formula I, i.e. Form II;

[0094] The yield of the above-mentioned crystal form II was 90% and the purity was 99% (PXRD spectrum confirmed the purity, powder diffractometer model and important parameters: Rigaku SmartLab, Cu-K target (tube voltage 40kV, tube flow 150mA)) (see Figure 5-8 ).

[0095] The X-ray powder diffraction pattern of the crystalline form II has diffraction peaks at the following 2θ values: 11.0±0.2°, 11.5±0.2°, 16.0±0.2°, 16.9±0.2°, 21.1±0.2°, 26.4±0.2°, and 27.3±0.2°;

[0096] 12.2±0.2°, 16.3±0.2°, 21.6±0.2°, 23.5±0.2°, 17.1±0.2°, 21.1±0.2°, 30.9±0.2°;

[0097] 9.3±0.2°, 11.4±0.2°, 16.3±0.2°, 19.9±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°;

[0098] 9.3±0.2°, 10.3±0.2°, 11.8±0.2°, 17.6±0.2°, 21.3±0.2°, 25.8±0.2°, 32.1±0.2°;

[0099] Unit cell parameters

[0100]

[0101] Space group: P-1.

[0102] Example 3

[0103] Obtaining Form III:

[0104] 5 mg of pyraclostrobin (compound of formula I) was heated at a rate of greater than 5°C / min (in this embodiment, the temperature was increased at a rate of 10°C / min) to 210°C, and then cooled to 195°C and allowed to stand for crystallization to obtain the compound Form III;

[0105] The yield of the prepared form III was greater than 95%, and the purity was above 99% (the purity was confirmed by single crystal diffractometer, instrument model and important parameters: Rigaku 007Saturn 70 (Rigaku, Japan) instrument, Mo target Kα ray Collected at 113.15k) (see Figure 9-10 ).

[0106] The X-ray powder diffraction pattern of the crystalline form III is selected from the following 2θ values ​​with diffraction peaks:

[0107] 6.5±0.2°, 10.9±0.2°, 12.7±0.2°, 17.1±0.2°, 21.1±0.2°, 23.8±0.2°, 27.5±0.2°;

[0108] 12.2±0.2°, 16.3±0.2°, 21.6±0.2°, 23.5±0.2°, 17.1±0.2°, 21.1±0.2°, 30.9±0.2°;

[0109] 9.3±0.2°, 11.4±0.2°, 16.3±0.2°, 19.9±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°;

[0110] 9.3±0.2°, 10.3±0.2°, 11.8±0.2°, 17.6±0.2°, 21.3±0.2°, 25.8±0.2°, 32.1±0.2°;

[0111] Unit cell parameters

[0112]

[0113] Space group: P21 / n.

[0114] Example 4

[0115] The preparation of Form IV is obtained by the following different methods:

[0116] 5 mg of pyraclostrobin (compound of formula I) was heated to 205° C. at a rate of 5° C. / min, and then cooled to 196° C., and crystallized by standing to obtain the compound in form IV;

[0117] The yield of the prepared form IV was greater than 95%, and the purity was above 99% (the purity was confirmed by single crystal diffractometer, instrument model and important parameters: Rigaku 007Saturn 70 (Rigaku, Japan) instrument, Mo target Kα ray Collected at 113.15k) (see Figure 11-12 ).

[0118] The X-ray powder diffraction pattern of the crystalline form IV is selected from the following 2θ values ​​with diffraction peaks:

[0119] 6.5±0.2°, 11.6±0.2°, 13.1±0.2°, 15.4±0.2°, 16.0±0.2°, 21.4±0.2°, 25.4±0.2°;

[0120] 9.3±0.2°, 20.3±0.2°, 21.4±0.2°, 15.4±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°;

[0121] 9.3±0.2°, 11.6±0.2°, 13.3±0.2°, 17.6±0.2°, 21.6±0.2°, 21.6±0.2°, 25.8±0.2°;

[0122] Unit cell parameters

[0123]

[0124] Space group: P-1.

[0125] Example 5

[0126] Obtaining Form V:

[0127] 1000 mg of pyraclostrobin (compound of formula I) was added to 2 ml of dichloromethane at 25° C., mixed and dried to obtain the crystal form of the compound of formula I, i.e., crystal form V;

[0128] The yield of the obtained Form V was 95% and the purity was 98% (PXRD spectrum confirmed the purity, powder diffractometer model and important parameters: Rigaku SmartLab, Cu-K target (tube voltage 40kV, tube flow 150mA)) (see Figure 13-15 ).

[0129] The X-ray powder diffraction pattern of the crystalline form V has diffraction peaks selected from the following 2θ values:

[0130] 6.4±0.2°, 11.7±0.2°, 12.8±0.2°, 13.6±0.2°, 14.6±0.2°, 25.7±0.2°, 27.2±0.2°;

[0131] 12.2±0.2°, 16.3±0.2°, 21.6±0.2°, 23.5±0.2°, 13.7±0.2°, 24.0±0.2°, 30.9±0.2°;

[0132] 9.3±0.2°, 11.4±0.2°, 12.8±0.2°, 13.6±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°;

[0133] 1.4±0.2°, 11.7±0.2°, 13.3±0.2°, 17.6±0.2°, 21.3±0.2°, 25.8±0.2°, 32.1±0.2°;

[0134] Example 6

[0135] Obtaining Form VI:

[0136] 5 mg of pyraclostrobin (compound of formula I) was heated to 230° C., then cooled to 25° C., and allowed to stand to obtain the compound crystal form VI.

[0137] The yield of the prepared form VI is greater than 98% and the purity is above 99% (PXRD spectrum confirms the purity, powder diffractometer model and important parameters: Rigaku SmartLab, Cu-K target (tube voltage 40kV, tube flow 150mA)) (see Figure 16-17 ).

[0138] The crystal form VI is amorphous, and its X-ray powder diffraction pattern shows a steamed bun peak at (5-35°).

[0139] Example 7

[0140] Obtaining of Form VII (hydrate):

[0141] 500 mg of pyraclostrobin (compound of Formula I) was added to butanone until completely dissolved, filtered through an organic filter membrane, magnetically stirred at 25° C., and water was added to the solution until solids precipitated, which was then filtered and dried to obtain the compound crystalline Form VII;

[0142] The yield of the prepared form VII was 85% and the optical purity was 99% (PXRD spectrum confirmed the purity, powder diffractometer model and important parameters: Rigaku SmartLab, Cu-K target (tube voltage 40kV, tube current 150mA)) (see Figure 18-21 ).

[0143] The X-ray powder diffraction pattern of the crystalline form VII has diffraction peaks at the following 2θ values: 10.5±0.2°, 11.2±0.2°, 13.6±0.2°, 16.5±0.2°, 17.6±0.2°, 21.1±0.2°, and 24.5±0.2°;

[0144] 13.1±0.2°, 16.5±0.2°, 21.6±0.2°, 23.5±0.2°, 13.7±0.2°, 24.5±0.2°, 30.9±0.2°;

[0145] 9..3±0.2°, 11.4±0.2°, 12.8±0.2°, 17.0±0.2°, 21.3±0.2°, 22.3±0.2°, 25.2±0.2°;

[0146] 5.4±0.2°, 11.2±0.2°, 13.3±0.2°, 17.6±0.2°, 21.3±0.2°, 26.7±0.2°, 32.1±0.2°;

[0147] Unit cell parameters

[0148]

[0149] Space group: P-1.

[0150] Application Examples

[0151] Solubility test

[0152] 1) At 25°C, the solubility of the crystalline forms obtained in the above examples in water was tested (see the table below). The results showed that the solubility of crystalline forms II and V was significantly better than that of crystalline form I.

[0153]

[0154] 2) Accelerated stability test:

[0155] Take appropriate amount of the crystalline powder obtained in the above embodiment to be tested and put it into respective sample bottles, seal them and place them in a constant temperature box at 50±2℃ for 90 days. Take samples from the constant temperature box on the 10th day, 30th day and 90th day respectively, cool them to room temperature and test their PXRD. The PXRD spectrum ( Figure 22-26 ) were compared to determine the storage and crystal transformation of each crystal form. The test results showed that, with the exception of the amorphous form (VI), several other solid forms, including the hydrate (form VII), were able to exist stably within the maximum test period (3 months). The detailed results are as follows:

[0156]

[0157] 3) Water suspension stability test: At 25°C, the crystalline powder obtained in the above example was placed in a glass sample bottle filled with 10 mL of high-purity water. A magnetic rod was added, the bottle was sealed, and the mixture was stirred at 300 rpm. Samples were taken with a pipette at 8 h, 24 h, 48 h, and 168 h, and the PXRD results were directly tested after filtration. The PXRD spectrum ( Figure 27-31 ) Comparison and evaluation of the suspension stability of each crystalline form in water were conducted. Samples of Form V were taken after one week and found to have transformed into a hydrate (Form VII). The amorphous form (Form VI) first transformed into Form II after 8 hours, and then into a hydrate (Form VII) after one week. Detailed results are as follows:

[0158]

[0159] Indoor herbicidal activity assay:

[0160] The experiment selected barnyard grass as the test weed. The test material culture, pesticide preparation and treatment were performed according to the national agricultural industry standard, i.e., Pesticide Indoor Biological Test Standard Herbicide Part 4: Activity Test Stem Leaf Spray Method (N / Y 1155.4-2006).

[0161] Investigation method 1: A series of concentration gradient suspending agents were respectively configured for each crystal form. After 21 days of indoor test treatment, the growth state of the test barnyard grass was observed and recorded, and the fresh weight of the aboveground part was weighed, the fresh weight control effect E (%) of each crystal form was calculated and compared, E = (C-T) / C*100, wherein E is the fresh weight control effect, C is the fresh weight of the aboveground part of the control barnyard grass, and T is the fresh weight of the aboveground part of the treated barnyard grass. The logarithmic value of the dose of the pesticide and the probability value of the control effect were subjected to regression analysis by using the standard statistical software DPS or SPSS, and the ED 98 (98% effective drug dose) and the 95% confidence interval were respectively calculated. The test result statistical analysis is as follows:

[0162]

[0163] Investigation method 2: After 21 days of 1.25 g / mu suspending agent test treatment, the growth state of the test barnyard grass was observed and recorded, and the fresh weight of the aboveground part was weighed, the fresh weight control effect E (%) of each crystal form was calculated and compared, E = (C-T) / C*100, wherein E is the fresh weight control effect, C is the fresh weight of the aboveground part of the control barnyard grass, and T is the fresh weight of the aboveground part of the treated barnyard grass.

[0164] Herbicidal activity grading evaluation:

[0165] A class - very high activity, control effect 90-100%;

[0166] B class - high activity, control effect 80-90%;

[0167] C class - relatively high activity, control effect 70-80%;

[0168] D class - moderate activity, control effect 50-70%;

[0169] E class - low activity, control effect 10-50%;

[0170] F class - almost no activity, control effect 0-10%;

[0171] Indoor herbicidal activity experiment results of each crystal form (1.25 g / mu suspending agent):

[0172] Crystal form name Form I Form II Crystalline Form VII (hydrate) Evaluation level C A A

[0173] The above-mentioned barnyardgrass control activity test results show that under the experimental conditions, the three crystal forms involved in the present invention have large differences in weed control effects, and crystal forms II and VII have significantly better weed control effects than the currently commercially available crystal form I.

[0174] Field trials

[0175] Crop experiment: Three rice varieties (three leaves and one heart, namely, Gujing, Zhongxianghuangzhan and Xiuzhan 15), three barnyard grasses, and one Leptochloa

[0176] Weed test method: 20m 2 Each treatment was repeated 3 times for one plot. The rice was sprayed on the stems and leaves 12 days after direct seeding. Water was applied 48 hours after spraying and the water was retained for 5-7 days.

[0177] 20 days after treatment, the treated and control areas were observed and the weed control efficacy and crop safety were calculated using the same survey method as in Test Example 1 by visual inspection.

[0178] Experimental location: Sanya, Hainan

[0179] The results are listed in Table 1.

[0180] Table 1: Field herbicidal activity test results of compound 2

[0181]

[0182] The above results show that the effects of the crystal forms involved in the field experiment on barnyard grass are consistent with the indoor results, and they have outstanding weed control effects on weeds and are very safe for wheat. At the same time, crystal forms II and VII have significantly better weed control effects than the currently commercially available crystal form I.

Claims

1. A crystalline form II of quinoxaline, characterized in that: The structural formula of Form II is , the unit cell parameters are as follows Space group: P-1.

2. A method for preparing the pyraclostrobin crystal form II according to claim 1, characterized in that: Pyraclostrobin is added to a solvent at 5-100° C., mixed and dried to obtain pyraclostrobin crystal form II; the solvent is n-hexane; the pyraclostrobin structural formula is .

3. An application of the pyraclostrobin crystal form II according to claim 1, characterized in that: Application of the pyraclostrobin crystal form II in the preparation of herbicides.

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