CN115947696A - High-purity thermodynamically stable amicarbazone crystal and preparation method thereof - Google Patents

Abstract

The invention provides a high-purity thermodynamically stable amicarbazone crystal and a preparation method thereof, and relates to the technical field of herbicides

Cell parameters of

α =114.163 °, β =119.268 °, γ =94.136 °, and the purity of the amicarbazone crystals is above 96.5%. The preparation method comprises the following steps: preparing amicarbazone crystal seed, and carrying out induced crystallization by utilizing the amicarbazone crystal seed. The amicarbazone crystals of the application are thermodynamically more stable and are amorphous than the prior crystalsCompared with amicarbazone in a form of a crystal or a shape, the amicarbazone has better herbicidal activity, and especially improves the herbicidal effect of two weeds of barnyard grass and switchgrass.

Description

High-purity thermodynamically stable amicarbazone crystal and preparation method thereof

Technical Field

The invention relates to the technical field of herbicides, in particular to a high-purity thermodynamically stable amicarbazone crystal and a preparation method thereof.

Background

Amicarbazone is developed by Bayer corporation plant protection department and belongs to triazolinone herbicides. Amicarbazone is a photosynthesis inhibitor, and typical symptoms of response to sensitive plants are chlorosis, growth cessation, and tissue withering to death. Amicarbazone can be used to effectively control major annual broadleaf weeds in corn and sugarcane fields and many annual grass weeds in sugarcane fields.

Patent US5194085A and patent US5708184A disclose a process for the preparation of amicarbazone. The method uses tert-butyl isocyanate and 4-amino-3 isopropyl-1H-1, 2, 4-triazole-5- (4H) ketone to carry out condensation reaction to obtain the amicarbazone.

The Acta Crystallographica Section E: structure Reports,2013, vol69,603 Reports a triclopyr crystal having a melting point of 373-378K (100-105 ℃), and discloses a specific single crystal Structure in detail. The crystals are obtained by recrystallization of amicarbazone obtained by the preparation process disclosed in patent US5708184A in a methyl tert-butyl ether solvent.

Patent CN108699010 discloses another crystalline form of amicarbazone with a melting point of 127-132 ℃, and discloses XRD diffraction data. The crystal is obtained by recrystallizing amorphous amicarbazone obtained by the preparation method disclosed in the patent US5194085A in methyl ethyl ketone solvent.

The present inventors have surprisingly discovered a novel crystal of amicarbazone which is highly pure and thermodynamically more stable during the development of amicarbazone products, and have further discovered that the crystal exhibits unexpectedly superior effects in herbicidal activity as compared to the existing amorphous or crystalline forms of amicarbazone.

Disclosure of Invention

The invention provides a high-purity thermostable amicarbazone (formula I) crystal and a preparation method thereof. The amicarbazone (formula I) crystal is not only more thermodynamically stable, but also has better herbicidal activity compared with the existing amorphous or crystal form of amicarbazone, especially against two weeds, namely barnyard grass and switchgrass.

In a first aspect, the present invention provides a high purity, thermodynamically more stable crystalline amicarbazone (formula I) having a purity of greater than 96.5%; preferably, the purity is 98-99.5%; more preferably, the purity is 99% to 99.2%; the melting point of the amicarbazone (formula I) crystal is 138-143 ℃; preferably, the melting point is 139 to 141 ℃;

the amicarbazone (formula I) crystal belongs to triclinic crystal, and the specific crystal form parameters are listed as follows:

the above parameters have the following meanings:

a. b, c = length of side of unit cell;

α, β, γ = angle of unit cell;

z = number of molecules in unit cell.

The above amicarbazone crystals exhibit in any combination at least 3, preferably at least 4, more preferably at least 5, and most preferably all, of the X-ray powder diffraction (PXRD) recorded at 25 ℃ with Cu-ka radiation as the following reflections at 2 theta (± 0.2 °):

2θ＝6.73±0.2° (1)

2θ＝6.98±0.2° (2)

2θ＝7.67±0.2° (3)

2θ＝10.78±0.2° (4)

2θ＝11.41±0.2° (5)

2θ＝15.36±0.2° (6)

2θ＝17.46±0.2° (7)

2θ＝19.58±0.2° (8)

2θ＝22.84±0.2° (9)

2θ＝26.75±0.2° (10)

2θ＝28.74±0.2° (11)

2θ＝31.03±0.2° (12)

2θ＝35.46±0.2° (13)

2θ＝36.10±0.2° (14)。

in the present invention, the term X-ray powder diffraction Pattern (PXRD) refers to the experimentally observed diffraction pattern or parameters derived therefrom. The powder X-ray diffraction pattern is characterized by the peak position (abscissa) and the peak intensity (ordinate).

Further, amicarbazone crystals exhibit in any combination at least 3, second preferably at least 4, more preferably at least 5, and most preferably all, as reflections at 2 θ (± 0.2 °) angles in X-ray powder diffraction (PXRD) recorded at 25 ℃ with Cu-ka radiation:

2θ＝6.73±0.2° (1)

2θ＝10.78±0.2° (4)

2θ＝11.41±0.2° (5)

2θ＝15.36±0.2° (6)

2θ＝17.46±0.2° (7)

2θ＝19.58±0.2° (8)

2θ＝22.84±0.2° (9)。

in a second aspect, the present invention provides a process for the preparation of crystalline seeds of amicarbazone crystals having high purity and being thermodynamically stable, the process being a specially developed mode of crystallization comprising the steps of:

mixing amorphous amicarbazone and acetic acid, heating to 60-80 ℃, filtering insoluble matrix substances, adding water, slowly cooling, keeping the temperature for 20 ℃ per hour, standing when the temperature is reduced to 20 ℃, slowly volatilizing the solvent, crystallizing, continuously standing at room temperature for 1 week, and collecting precipitated crystals to obtain the crystal seeds of the amicarbazone crystals.

In a third aspect, the present invention provides a process for the efficient preparation of highly pure, thermodynamically stable amicarbazone crystals, in a specially developed controlled crystallization regime, comprising the steps of:

dissolving amorphous amicarbazone in a solvent, heating to 30-100 ℃ for dissolving, cooling to 10-30 ℃, adding crystal seeds of the amicarbazone crystals prepared by the preparation method of claim 5 in the cooling process, crystallizing, and filtering to obtain high-purity and thermodynamically stable amicarbazone crystals;

the solvent is one or more selected from acetonitrile, toluene, chloroform and methanol.

The crystallization is caused by adding a solvent or water which decreases the solubility;

the weight/volume ratio of the amicarbazone crystals to the solvent is 1;

a possible advantageous way of crystallization before addition of the seeds of amicarbazone crystals is after the dissolution step but before the crystallization step, which may be done by:

adding a solubility-reducing organic solvent to the solution comprising dissolved amorphous amicarbazone;

concentrating the solution comprising dissolved amorphous amicarbazone;

cooling the solution comprising dissolved amorphous amicarbazone or a combination of the above.

The seed crystal of the amicarbazone crystal is added in an amount of 0.01-20 wt% (weight percentage), preferably 0.05-5 wt%.

By controlled crystallization is meant that crystallization is carried out at different temperature stages, the crystallization taking place in total for a period of at least 1 hour to several hours or more, and also for a period of up to several days, e.g. a 1-2 week extension. The crystallization is usually carried out for 1 to 72 hours, in particular for 3 to 24 hours.

In a fourth aspect, the present invention provides a herbicide prepared by formulating the above amicarbazone crystal as an active ingredient.

The amicarbazone crystal provided by the invention is more thermodynamically stable, and compared with the existing amicarbazone in an amorphous or crystal form, the amicarbazone crystal shows an unexpected excellent effect in weeding activity, and the weeding activity on weeds is obviously improved, especially the weeding effect on two weeds, namely barnyard grass and bran millet.

In a fifth aspect, the present invention provides a herbicide containing amicarbazone, comprising a mixture of amicarbazone crystals with one or more selected from group B;

group B:

b-1: acetolactate synthase inhibitors;

b-2: acetyl-coa carboxylase inhibitors;

b-3: protoporphyrinogen IX oxidase inhibitors;

b-4: 4-hydroxyphenylpyruvate dioxygenase inhibitor;

b-5: inhibitors of phytoene desaturase;

b-6: a photosystem II inhibitor;

b-7: inhibitors of the synthesis of ultra-long chain fatty acids;

b-8: inhibitors of tubulin synthesis;

b-9: an auxin-type herbicide;

b-10: an enolpyruvylsarco phosphate synthase inhibitor;

b-11: (ii) a glutamine synthetase inhibitor; and

b-12: other herbicides.

Preferably, the group B is selected from one or more of nicosulfuron, mesotrione, furaltadone, isoxaflutole, fluroxypyr, atrazine, trifloxysulfuron, primisulfuron, flufenacet.

In a sixth aspect, the invention provides a herbicide composition, wherein the amicarbazone crystal and a pesticide adjuvant are prepared into any agriculturally suitable dosage form, preferably, the dosage form is a suspending agent, a water dispersible granule or a wettable powder.

The beneficial effects of the invention are as follows:

(1) The amicarbazone crystals with the melting point of 138-143 ℃ discovered by the invention are thermodynamically more stable crystals. Can be stored simply and conveniently at room temperature, does not generate crystal transformation phenomenon, and does not influence the further processing and application of products.

(2) The seed crystal obtained by the specific preparation method of the amicarbazone crystal seed provided by the invention has high purity.

(3) The method for preparing the amicarbazone crystals by inducing the high-purity seed crystals is efficient and suitable for large-scale production.

(4) The amicarbazone crystal provided by the invention can be conveniently and directly used in an agricultural preparation, especially a more environment-friendly solid preparation such as a suspending agent, a water dispersible granule, a wettable powder and the like, has obviously improved herbicidal activity on weeds, and especially has herbicidal effect on two weeds such as barnyard grass and switchgrass.

(5) The solid preparation prepared from the amicarbazone crystal and other active herbicide compositions provided by the invention can be widely applied to the control of weeds in crops.

Drawings

FIG. 1 is a graph of X-RAY of amicarbazone crystals according to example B of the present invention.

FIG. 2 is a DSC of crystalline amicarbazone according to example 1 of the present invention.

Figure 3 is an XRD pattern of amicarbazone crystals according to example 1 of the present invention.

FIG. 4 is an X-RAY diagram of crystalline amicarbazone according to example 1 of the present invention.

Detailed Description

The following examples are for clear and complete description of the technical solution of the present invention; it is to be understood that the disclosed embodiments are merely exemplary of the invention, and are not intended to be exhaustive or exhaustive. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

All XRD patterns were determined using an X-ray diffractometer in reflection geometry at 25 ℃ using the following acquisition parameters:

the instrument name: an X-ray diffractometer;

the product model is as follows: x' Pert PRO;

the manufacturer: PNAlytical, netherlands;

light pipe target material: a Cu target;

x-ray wavelength: cu Ka (0.1541 nm);

voltage: 40kV;

current: 40mA;

a detector: an X' Celerator hyper-energy detector;

scanning range: the abscissa start-end values of xy-format data;

step length: the difference between any two abscissa values in the xy format is typically 0.033 °.

All DSC plots were determined using the following acquisition parameters:

the instrument name: mettleltoduo;

the product model is as follows: mettler-Toledo DSC1/400;

measurement parameters are as follows: the initial temperature is 25 ℃, and the temperature is increased by 10 ℃/min; the final temperature was 550 ℃.

All X-RAY plots were determined using the following acquisition parameters:

the instrument name: a single crystal diffractometer;

the product model is as follows: gemini AUltra;

the manufacturer: oxford (warian) british;

measurement parameters are as follows: -103 ℃.

The purity was determined by HPLC using the following parameters:

the instrument name: a high performance liquid chromatograph;

the model is as follows: SPD-20A;

the manufacturer: shimadzu corporation.

Example A: preparation of amorphous azaconazole reported in patent US5708184A

200ml of methyl acetate, 31.3g (2.35 mol content: 96%) of triazolinone (4-amino-3-isopropyl-5-oxo-1H-1, 2, 4-triazol-3-one), 0.3g (0.05 mol) of potassium hydroxide and 0.2g (0.047 mol) of lithium chloride are added into a reaction bottle with a stirring device and a thermometer, the temperature is raised to 55-60 ℃ under the stirring state, 25.6g (2.58 mol) of tert-butyl isocyanate is dripped into the reaction bottle, the reaction bottle is refluxed for 3H, cooled to 20 ℃, filtered, the filtrate is washed by water and then layered, the solvent is removed by reduced pressure distillation, and the residue in the reaction bottle is dried under the vacuum state at 60 ℃ to obtain 57.8g of amorphous amicarbazone with the content of 94%.

Example B: preparation of amicarbazone triclinic crystal reported in the Crystal proceedings

Reference is made to the Crystal science (Acta Crystagonococcus Section E: structure Reports,2013, vol69, 603) preparation method.

5g of amorphous amicarbazone prepared in example A was weighed, and recrystallized by adding methyl tert-butyl ether, and the solvent was slowly evaporated to obtain crystals. As shown in FIG. 1, the diffraction data of the analyzed X single crystal was consistent with the data reported in the Crystal science, but the melting point was measured to be 137 ℃.

Example C: preparation of amicarbazone crystal modification I reported in CN 108699010A reference is made to the preparation method of patent CN 108699010A.

Weighing 5g of amorphous amicarbazone prepared in example A, dissolving in 35ml of nitrobenzene, heating to 60 ℃ for dissolution, stirring at the temperature for 2h, filtering at the temperature, filtering to remove insoluble matrix substances, slowly cooling the solution to 20 ℃, separating out crystals, stirring at the temperature for 2h, filtering the slurry, and washing with nitrobenzene at 20 ℃; and dried under vacuum at 45 ℃ to give crystalline modification I of amicarbazone as reported in patent CN 108699010A.

Example 1: preparation of crystalline amicarbazone seeds

Weighing 0.5g of amorphous amicarbazone prepared in example A, adding 5ml of acetic acid, heating to 70 ℃ to dissolve solids, filtering out insoluble matrix substances, dropwise adding 1ml of water, slowly cooling, keeping the temperature for 20 ℃ per hour, standing for 2 days when the temperature is reduced to 20 ℃, slowly volatilizing the solvent for crystallization, standing for 1 week at room temperature continuously, finding that colorless transparent flaky crystals are separated out, pouring out residual clear liquid, collecting the colorless transparent flaky crystals, analyzing the obtained crystals by DSC, XRD and X-RAY as shown in figures 2, 3 and 4 respectively, and finding that the crystals are amicarbazone crystal seeds.

The crystal seed of the amicarbazone crystal is subjected to an X-RAY single crystal diffraction test, and the measured unit cell parameters are shown in Table 1:

TABLE 1

The amicarbazone crystal seed crystals obtained above were subjected to X-ray powder diffraction (PXRD) with Cu-Ka radiation at 25 deg.C, and the X-ray powder diffraction 2 theta (plus or minus 0.2 deg.) angle was measured, and the data was recorded as follows:

6.73(1)

6.98(2)

7.67(3)

10.78(4)

11.41(5)

15.36(6)

17.46(7)

19.58(8)

22.84(9)

26.75(10)

28.74(11)

31.03(12)

35.46(13)

36.10(14)。

example 2: preparation of amicarbazone crystals

Weighing 15g of amorphous amicarbazone prepared by the method in the embodiment A, adding 20g of methanol, heating and refluxing to dissolve the solid, and filtering out insoluble matrix substances; adding 5g of toluene, slowly cooling to 20 ℃, adding the crystal seeds of the amicarbazone crystals prepared in example 1, stirring for 18 hours, and filtering to obtain the amicarbazone crystals with the purity of 98%, the melting point of 139 ℃ in DSC detection, wherein the crystal form is the same as that in example 1 in XRD detection.

Example 3: preparation of amicarbazone crystals

Weighing 50g of amorphous amicarbazone prepared by the method in the embodiment A, adding 150g of chloroform, heating to reflux, dissolving the solid clearly, and filtering out insoluble matrix substances; then removing part of chloroform, adding the crystal seed of the amicarbazone crystal prepared in the example 1, slowly cooling, stirring for 10 hours, and filtering to obtain the amicarbazone crystal with the purity of 96.5 percent, the melting point of 138.5 ℃ by DSC detection, wherein the crystal form of the amicarbazone crystal is the same as that of the crystal seed prepared in the example 1 by XRD detection.

Example 4: preparation of amicarbazone crystals

Weighing 10g of crystalline amicarbazone prepared by the method in the embodiment B, adding 10g of acetic acid, heating to reflux, dissolving the solid clearly, and filtering out insoluble matrix substances; then, 5g of toluene is added into the seed crystal of the amicarbazone crystal prepared in the example 1, the temperature is slowly reduced, the stirring is carried out for 8 hours, and the amicarbazone crystal with the purity of 99.1 percent and the melting point of 140.1 ℃ detected by DSC is obtained through filtering, and the crystal form of the amicarbazone crystal is the same as that of the amicarbazone crystal in the example 1 detected by XRD.

Example 5: preparation of amicarbazone crystals

Weighing 10g of crystalline amicarbazone prepared by the method in the embodiment C, adding 20g of acetonitrile, heating to reflux, dissolving the solid clearly, and filtering out insoluble matrix substances; then removing about 10g of acetonitrile, adding the crystal seeds of the amicarbazone crystals prepared in the example 1, slowly cooling, stirring for 10h, and filtering to obtain the amicarbazone crystals with the purity of 99.2 percent, the melting point of 140.0 ℃ detected by DSC, wherein the crystal form of the amicarbazone crystals is the same as that of the crystal form of the amicarbazone crystals in the example 1 detected by XRD.

Example 6: amicarbazone crystal form thermodynamic stability test

The amicarbazone crystal prepared in example 2 is placed in a high-temperature (50 +/-2 ℃) oven for 10 days, and samples are respectively taken on the 5 th day and the 10 th day for X-ray powder diffraction analysis, and the result shows that the 2 theta angle of the X-powder diffraction of the amicarbazone crystal compound is consistent with that before storage, which indicates that the amicarbazone crystal compound belongs to a thermodynamically stable crystal form.

Example 7: comparative test for biological activity of amicarbazone crystals

Test samples: preparing the amicarbazone crystals prepared by the method in the example 2 into a test medicament, wherein the code of the medicament is A; preparing the crystalline amicarbazone prepared by the method in the example B into a test medicament, wherein the code of the medicament is B; the crystalline amicarbazone prepared by the method in example C is prepared into a test medicament, and the medicament code is C.

The ingredients and amounts of each test agent are detailed in table 2.

TABLE 2

Examples	Example 2	Example B	Example C
				Test agent	A	B	C
Amicarbazone technical product	70.7％	70.7％	70.7％
				Sodium dodecyl sulfate	4％	4％	4％
Lignosulfonic acid sodium salt	5％	5％	5％
				White carbon black	2.5％	2.5％	2.5％
Sodium tallow fatty acid salt	0.5％	0.5％	0.5％
				Corn starch	17.3％	17.3％	17.3％
Total of	100％	100％	100％

The preparation process of the test medicament is as follows:

weighing amicarbazone, sodium dodecyl sulfate, sodium lignosulfonate, white carbon black, sodium tallowate and corn starch according to a formula proportion, uniformly stirring and mixing, and then crushing by an airflow crushing system until the average particle size is less than 5 microns to obtain the test medicament.

Test targets: barnyard grass, bran millet.

Design of experiments

Dose design: 30g a.i./ha, 45g a.i./ha, 60g a.i./ha, 90g a.i./ha, 120g a.i./ha, 180g a.i./ha, 360g a.i./ha.

Test method

The greenhouse potting method is characterized in that the test soil is soil mixed with laboratory clay and a seedling raising matrix in a volume ratio of 1. Spraying the stem and leaf after seedling. The intelligent biological testing spray tower (HCL-2000) walking type spray tower is adopted for uniform spraying, the spraying pressure is 0.2MPa, the water adding amount is 40L/mu, and the distance between a spray head and a test material is about 50 cm. After the application of the pesticide, all treatments are placed in a plastic greenhouse for growth and culture, and water is supplemented from the bottom of the pot in an infiltration irrigation mode to maintain the soil humidity.

And (4) measuring the fresh weight of the overground part, and calculating the inhibition rate% of the fresh weight. The dose of the medicament is converted into logarithm by using EXCEL software, and the effective dose ED of 90 percent of the test medicament for inhibiting the growth (fresh weight) of the weeds is obtained by a linear regression equation of the logarithm of the dose of the medicament-fresh weight inhibition rate ₉₀ See table 3 for details.

The comparative test results of the post-emergence stem leaf treatment herbicidal activity of each test sample are detailed in table 4.

TABLE 3

TABLE 4

According to tables 3 and 4, the post-emergence stem leaf treatment of each test sample (A (example 2), B (example B) and C (example C)) showed a fresh weight inhibition ratio of-33.2% to 99.9%, -9.1% to 99.3%, -23.2% to 90.9% for barnyard grass, and ED90 values of the fresh weight inhibition ratio were 231.9g a.i./ha, 257.8g a.i./ha and 282.7g a.i./ha, respectively, at 22 days after the application, and the herbicidal activity of each test sample for barnyard grass was ranked as A > B > C under the post-emergence stem leaf treatment conditions.

According to tables 3 and 4, the post-emergence stem and leaf treatment inhibition rates of the test samples (A (example 2), B (example B) and C (example C)) on the fresh weight of the switchgrass at 22 days after the treatment are respectively 36.1-100%, 27.5-100% and 36.3-100%, the ED90 values of the inhibition rates of the fresh weight are respectively 97.9g a.i./ha, 116.6g a.i./ha and 119.4g a.i./ha, and the herbicidal activity of the test samples on the switchgrass under the post-emergence stem and leaf treatment condition is ranked as A > B ≧ C.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the spirit of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A high-purity thermodynamically stable amicarbazone (formula I) crystal, characterized in that the amicarbazone (formula I) crystal is a triclinic crystal, the space group is P1, and the unit cell parameter is

α =114.163 °, β =119.268 °, γ =94.136 °; the purity of the amicarbazone (formula I) crystals is more than 96.5%; preferably, the purity is 98-99.5%; more preferably, the purity is 99% to 99.2%;

2. the high purity, thermodynamically stable amicarbazone (formula I) crystal according to claim 1, characterized in that said amicarbazone (formula I) crystal exhibits at least 3 of the following reflections as 2 Θ (± 0.2 °) angles in any combination in recorded X-ray powder diffraction (PXRD) with Cu-ka radiation at 25 ℃:

2θ＝6.73±0.2° (1)

2θ＝6.98±0.2° (2)

2θ＝7.67±0.2° (3)

2θ＝10.78±0.2° (4)

2θ＝11.41±0.2° (5)

2θ＝15.36±0.2° (6)

2θ＝17.46±0.2° (7)

2θ＝19.58±0.2° (8)

2θ＝22.84±0.2° (9)

2θ＝26.75±0.2° (10)

2θ＝28.74±0.2° (11)

2θ＝31.03±0.2° (12)

2θ＝35.46±0.2° (13)

2θ＝36.10±0.2° (14)。

3. a high purity, thermodynamically stable amicarbazone (formula I) crystal according to any one of claims 1 to 2, characterized in that said amicarbazone (formula I) crystal exhibits in any combination at least 3 of the following reflections as 2 Θ (± 0.2 °) angles in X-ray powder diffraction (PXRD) recorded at 25 ℃ with Cu-ka radiation:

2θ＝6.73±0.2° (1)

2θ＝10.78±0.2° (4)

2θ＝11.41±0.2° (5)

2θ＝15.36±0.2° (6)

2θ＝17.46±0.2° (7)

2θ＝19.58±0.2° (8)

2θ＝22.84±0.2° (9)。

4. the high purity, thermodynamically stable amicarbazone (formula I) crystal according to any one of claims 1-2, wherein said amicarbazone (formula I) crystal has a melting point of 138-143 ℃; preferably; the melting point is 139-141 ℃.

5. A process for preparing high purity, thermodynamically stable crystalline seed crystals of amicarbazone (formula I), characterized in that:

mixing amorphous amicarbazone and acetic acid, heating to 60-80 ℃, filtering insoluble matrix substances, adding water, slowly cooling, keeping the temperature for 20 ℃ per hour, standing when the temperature is reduced to 20 ℃, slowly volatilizing the solvent, crystallizing, continuously standing at room temperature for 1 week, and collecting precipitated crystals to obtain the crystal seeds of the amicarbazone (formula I) crystals.

6. A method for efficiently preparing high-purity thermodynamically stable amicarbazone (formula I) crystals, which is characterized in that:

dissolving amorphous amicarbazone in a solvent, heating to 30-100 ℃ for dissolving, cooling to 10-30 ℃, adding crystal seeds of amicarbazone (formula I) crystals prepared by the preparation method of claim 5 in the cooling process, crystallizing, and filtering to obtain high-purity and thermodynamically stable amicarbazone (formula I) crystals;

the solvent is one or more selected from acetonitrile, toluene, chloroform and methanol.

7. The process for efficiently producing high purity, thermodynamically stable amicarbazone (formula I) crystals according to claim 6, wherein said crystallization is induced by the addition of a solubility-reducing solvent or water.

8. A herbicide, which is prepared by formulating the crystals of amicarbazone (formula I) according to any one of claims 1 to 2 as an active ingredient.

9. A herbicide formulation, as claimed in claim 8, which comprises amicarbazone (formula I) crystals and a mixture of one or more selected from group B;

group B:

b-1: an acetolactate synthase inhibitor;

b-2: acetyl-coa carboxylase inhibitors;

b-3: protoporphyrinogen IX oxidase inhibitors;

b-4: 4-hydroxyphenylpyruvate dioxygenase inhibitor;

b-5: inhibitors of phytoene desaturase;

b-6: a photosystem II inhibitor;

b-7: inhibitors of the synthesis of ultra-long chain fatty acids;

b-8: a tubulin synthesis inhibitor;

b-9: an auxin-type herbicide;

b-10: an enolpyruvylsarco phosphate synthase inhibitor;

b-11: (ii) a glutamine synthetase inhibitor; and

b-12: other herbicides.

10. A herbicide composition, which is prepared by mixing the amicarbazone (formula I) crystal according to any one of claims 1 to 2 with a pesticide adjuvant into any one of agriculturally suitable dosage forms, preferably, the dosage forms are suspending agents, water dispersible granules and wettable powder.

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