Preparation method of imazethapyr crystal and herbicide

Abstract

The invention relates to the technical field of pesticide crystals, and discloses a preparation method of imazethapyr crystals and a herbicide. The preparation method of the imazethapyr crystal comprises the following steps: 1) in the presence of water, contacting a sodium imazethapyr solution with hydrochloric acid to obtain a suspension; and 2) cooling the suspension, carrying out solid-liquid separation, drying, and baking to obtain imazethapyr crystals. According to the method, the thickness of the lamellar crystal can be remarkably increased, the original lamellar crystal habit is changed into a cubic-like crystal habit, so that the crystal is easier to roll, the fluidity of the imazethapyr crystal is remarkably enhanced, the bulk density can reach 0.5 g / mL or above, and no organic solvent or additive is adopted in the preparation process, so that the imazethapyr crystal is green and environment-friendly, and is suitable for industrial production. And large-scale industrial production and application are facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of pesticide crystallization, and in particular to a preparation method of imazethapyr crystals and a herbicide. Background Art

[0002] Imidazolin is a highly effective and selective herbicide, commonly used to remove annual grass crabgrass, perennial grass white grass and broad-leaved Xanthium in peanut fields, soybean fields and woodlands. The molecular formula of this substance is C 15 H 19 N3O3, molecular weight is 289.14, the structural formula is as follows,

[0003]

[0004] From the molecular formula of the substance, it can be seen that all the chemical bonds in the molecule are covalent bonds with large bond energy, so the substance is not easy to decompose. The experimental results show that the substance needs to be heated to above 200°C to decompose significantly. Since the substance contains carboxyl groups, it can show weak acidity. Since the N atom is located on or adjacent to the conjugated structure, the electron cloud of the atom is easily dispersed, so the N atom of the molecule is difficult to react with H + Although the molecule contains a conjugated structure, it hardly absorbs light in the visible wavelength range, and its aqueous solution is colorless and transparent. Based on these properties, the crystal can be obtained by the reaction crystallization of sodium imidazolin and hydrochloric acid during the production process. The reaction equation is as follows:

[0005]

[0006] From formula (1), we can see that the reactants are strong acid and weak acid salt, which allows the reaction to proceed thoroughly. Imidazole acetylcholine is the main reaction product. The large amount of this product can easily make its concentration reach the maximum supersaturation concentration, so that the excess solute precipitates in the form of crystals. The unprecipitated part stays in the water to form a saturated solution. This part of the acetazole acetylcholine is ionized into acetylcholine ion and hydrogen ion, as shown in formula (2).

[0007]

[0008] From formula (2), it can be seen that after reaching ionization equilibrium, the imidazole acetyl nicotinic acid in water exists in two forms: molecules and acid radicals, and the solution is weakly acidic. In order to completely convert the raw materials into products, the hydrochloric acid added is excessive, so that the equilibrium moves in the opposite direction. Therefore, the solution after the reaction still contains hydrochloric acid, and the solution is strongly acidic. In addition, the solution system after the reaction also contains sodium chloride and water, and these substances need to be separated from the imidazole acetyl nicotinic acid crystals during the crystallization process.

[0009] The actual raw material liquid contains not only sodium imidazole ethyl nicotinic acid, but also many other impurities, making the solution appear light yellow. The raw material liquid used is an aqueous solution, in which the content of imidazole ethyl nicotinic acid is only 8.90wt%, and it also contains about 0.45wt% of isomer sodium salt, about 0.38wt% of diacid sodium salt, about 1.05wt% of methanol content, about 2.60wt% of sodium chloride, and about 0.99wt% of other impurities. These impurities will also react and remain in the solution after the reaction, limiting the improvement of the purity of the imidazole ethyl nicotinic acid crystal product.

[0010] The imidazole acetyl nicotinic acid crystal product is an odorless white powder composed of fine off-white flaky crystals. For this reason, the bulk density of the crystal is low, and there is a disadvantage of a large packaging volume in application. The existing crystallization method is to directly mix the two reaction solutions, and the locally generated supersaturation is very high. The solution will nucleate due to the maximum supersaturation, and the crystal surface will also have induced nucleation. In the crystallization process, the rectangular flaky crystals obtained by the existing reaction crystallization method are characterized by a very small ratio of thickness to bottom side length, and the largest is less than 0.2. This feature makes the crystal rolling very poor, and the fluidity of the crystal product is poor; the crystals are also easy to stick together and difficult to wash thoroughly, so that more mother liquor and impurities remain. In order to solve this problem, it is necessary to increase the bulk density of the crystal, which requires changing the shape of each crystal. After careful observation of the crystals, it was found that the crystals were rectangular flakes, and the inventors of the present application believe that this is the main reason for the substandard bulk density. At present, an important method for preparing imidazole acetyl nicotinic acid is to use imidazole acetyl nicotinic acid sodium to react and crystallize with hydrochloric acid, so it is particularly important to improve this reaction crystallization process. By using the currently widely used reaction crystallization method, hydrochloric acid is added to the imidazolin sodium solution, or the imidazolin sodium solution is added to hydrochloric acid, the bulk density of the obtained product is only 0.2398 g / mL and 0.1744 g / mL respectively. The crystals in the product are respectively as follows Figure 1 and Figure 2 As shown. Figure 1 and Figure 2 It can be seen that these crystals are also in the form of rectangular plates. Summary of the invention

[0011] The purpose of the present invention is to adjust the shape of the prepared crystals to be cubic, improve fluidity, and thus increase the bulk density. In order to overcome the problems existing in the prior art, the present invention provides a method for preparing imidazole ethyl nicotinic acid crystals, by which the thickness of the flaky crystals can be significantly increased, the original flaky crystal habit is changed into a quasi-cubic crystal habit, the crystals are more likely to roll, and the fluidity of the imidazole ethyl nicotinic acid crystal product is significantly enhanced, the bulk density can reach more than 0.5 g / mL, and no organic solvents and additives are used in the preparation process, which is green and environmentally friendly and convenient for large-scale industrial production and application.

[0012] In a first aspect, the present invention provides a method for preparing imidazolin crystals, wherein the method comprises the following steps:

[0013] 1) contacting the imidazoline sodium solution with hydrochloric acid in the presence of water to obtain a suspension;

[0014] 2) cooling the suspension and performing solid-liquid separation to obtain imidazoline crystals,

[0015] The volume ratio of water to sodium imidazolin solution is 0.6-6:1.

[0016] The concentration of the sodium imidazolin solution is 0.05-0.1 g sodium imidazolin / g water, the concentration of the hydrochloric acid is 5-20% by weight, and the volume ratio of the sodium imidazolin solution to the hydrochloric acid is 6-11:1.

[0017] Preferably, the volume ratio of the sodium imidazolin solution to hydrochloric acid is 7-9:1.

[0018] Preferably, the volume ratio of water to sodium imidazolin solution is 1-5:1.

[0019] Preferably, the contact conditions include: temperature of 80-110° C. and time of 1-3 h.

[0020] Preferably, in step 2), the cooling rate is 0.1-0.5°C / min.

[0021] Preferably, the method further comprises the steps of washing and drying the solid phase obtained by solid-liquid separation.

[0022] Preferably, the drying includes first-stage drying and second-stage drying.

[0023] Preferably, the conditions for the first stage of drying include: vacuum drying at 20-60°C for 8-24 hours; more preferably, the conditions for the first stage of drying include: vacuum drying at 20-40°C for 12-24 hours.

[0024] Preferably, the conditions for the second stage of drying include: a temperature of 35-60° C. and a time of 8-13 h.

[0025] Preferably, the ratio of the crystal thickness of the imidazolin crystal to the side length of the bottom crystal surface is 0.2-1.

[0026] Preferably, based on the weight of the imidazole acetyl nicotinic acid crystals, when the amount of the imidazole acetyl nicotinic acid crystals whose ratio is not in the range of 0.2-1 is above 20 weight %, the method further comprises a grinding step.

[0027] Preferably, the bulk density of the imidazolin crystals is 0.5-0.8 g / mL.

[0028] The second aspect of the present invention provides a herbicide, which contains the imidazolin crystals prepared by the preparation method of the imidazolin crystals described in the first aspect of the present invention as an active ingredient.

[0029] Through the above technical solution, the thickness of the plate-like crystals can be significantly increased, so that the crystals form a cubic-like crystal habit, making the crystals easier to roll.

[0030] The crystal not only has a larger particle size, but also has a smaller aspect ratio. The crystal particles are easy to roll. Due to the enhanced fluidity, the crystal can be thoroughly washed, and the residual mother liquor and impurities are also less. Moreover, when the fluidity of the crystalline powder is enhanced, the bulk density is also improved. Therefore, the quality of the imidazolin crystal is significantly improved by the method of the present application.

[0031] Furthermore, no organic solvents or additives are used in the preparation process, which is green and environmentally friendly and convenient for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a picture of the imidazoline crystals obtained in Comparative Example 4.

[0033] Figure 2 This is a picture of the imidazoline crystals obtained in Comparative Example 5.

[0034] Figure 3 This is a picture of the cubic crystals of imidazolin obtained in Example 1. DETAILED DESCRIPTION

[0035] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0036] According to a first aspect of the present invention, a method for preparing imidazolin crystals is provided, wherein the method comprises the following steps:

[0037] 1) contacting the imidazoline sodium solution with hydrochloric acid in the presence of water to obtain a suspension;

[0038] 2) cooling the suspension and performing solid-liquid separation to obtain imidazoline crystals,

[0039] The volume ratio of water to sodium imidazolin solution is 0.6-6:1.

[0040] The concentration of the sodium imidazolin solution is 0.05-0.1 g sodium imidazolin / g water, the concentration of the hydrochloric acid is 5-20% by weight, and the volume ratio of the sodium imidazolin solution to the hydrochloric acid is 6-11:1.

[0041] In the present invention, the water is preferably deionized water. By adding a large amount of water, the concentration of the reactants is significantly reduced, the supersaturation of the reaction product is reduced, and the crystal surface and solution nucleation process are inhibited, the crystal can be well grown, not only the crystal size is increased, but also the crystal thickness is improved, making the crystal particles easier to roll.

[0042] According to the present invention, in order to obtain the cubic crystals of the present invention, preferably, the volume ratio of water to sodium imidazolin solution is 1-5: 1. When the imidazolin crystals are prepared by the volume ratio of the present invention, the crystal size is increased, the crystal thickness is improved, and the crystal particles are easier to roll.

[0043] In the present invention, the imidazolin sodium solution is an aqueous solution.

[0044] According to the present invention, preferably, the ratio of the thickness of the imidazole ethyl nicotinic acid crystals prepared by the preparation method of the present invention to the side length of the bottom crystal face is 0.2-1, and the quasi-cubic shape is obtained. When the quasi-cubic crystals with a ratio of the thickness to the side length of the bottom crystal face of 0.2-1 are obtained, the crystals are more likely to roll, and the fluidity is significantly enhanced, the crystals can be thoroughly washed, the residual mother liquor and impurities are also less, and the loose bulk density can be improved.

[0045] According to the present invention, preferably, based on the weight of the imidazole ethyl nicotinic acid crystals, when the ratio of the thickness to the side length of the bottom crystal surface of the imidazole ethyl nicotinic acid crystals prepared by the preparation method of the present invention exceeds 0.2-1 and the amount of the crystals is above 20 weight%, the method further comprises a grinding step.

[0046] Preferably, the grinding method comprises: grinding the crystals in a mortar.

[0047] Through the above grinding, the crystal can be broken into a cubic crystal (the ratio of thickness to the side length of the bottom crystal face is 0.2-1).

[0048] According to the present invention, in order to make the crystals more rolling and have better fluidity, preferably, the volume ratio of the sodium imidazolin solution to hydrochloric acid is 7-9:1.

[0049] In the present invention, step 1) may further include a step of diluting the hydrochloric acid, for example, purchasing 36 wt % concentrated hydrochloric acid, and adding deionized water to the concentrated hydrochloric acid to make its concentration between 5-20 wt %.

[0050] In a preferred embodiment of the present invention, the sodium imipenem solution and hydrochloric acid are added to water at different positions at the same time, so that the reactants in the two reaction solutions are greatly diluted when they meet, so that the supersaturation of the reaction product is very low, and the nucleation process of the solution and the crystal surface is inhibited, so that the crystals grow well, and the final crystals not only increase in size, but also increase in thickness.

[0051] According to the present invention, preferably, the contact conditions may include: temperature of 80-110° C., time of 1-3 h; more preferably, the contact conditions include: temperature of 90-100° C., time of 2-3 h.

[0052] According to the present invention, in step 2), the cooling operation can be carried out in the presence of a cooling medium, and the cooling medium commonly used in the art can be used without particular limitation, such as water. Preferably, the cooling rate is 0.1-0.5°C / min, more preferably 0.2-0.4°C / min. Too fast a cooling rate will lead to secondary nucleation of the solution and fine crystal particles, and too slow a cooling rate will lead to low production efficiency. During cooling, the temperature of the circulating medium is set to 10-20°C.

[0053] According to the present invention, in step 2), the solid-liquid separation can be carried out using a solid-liquid separation method commonly used in the art, without particular limitation. For example, a filtration method can be used to obtain a solid phase.

[0054] According to the present invention, water is used for washing. In order to prevent the solid phase obtained by solid-liquid separation from containing other impurities, preferably, the solid phase is washed with deionized water.

[0055] According to the present invention, preferably, the method further comprises a step of drying the solid phase after the washing.

[0056] According to the present invention, preferably, the drying includes first-stage drying and second-stage drying.

[0057] According to the present invention, in order to avoid dissolution of imidacloprid in the solid phase, the drying temperature should not be too high. Preferably, the conditions for the first stage of drying include: vacuum drying at 20-60°C for 8-24h; more preferably, the conditions for the first stage of drying include: vacuum drying at 20-40°C for 12-24h.

[0058] The conditions of the second stage drying include: temperature of 35-60°C and time of 8-13h.

[0059] According to the present invention, preferably, the bulk density of the imidazolin crystals is 0.5-0.8 g / mL. Since the imidazolin prepared by the preparation method of the imidazolin crystals of the present invention is a quasi-cubic crystal, the bulk density of the imidazolin crystalline powder can be significantly improved.

[0060] According to a second aspect of the present invention, there is provided a herbicide comprising imidacloprid crystals prepared by the preparation method of imidacloprid crystals according to the first aspect of the present invention as an active ingredient.

[0061] The present invention will be described in detail below by way of examples, but the present invention is not limited to the following examples.

[0062] Vacuum oven: purchased from Tianjin Maful Technology Co., Ltd., model DZF-1AB

[0063] Blast drying oven: purchased from Tianjin Maful Technology Co., Ltd., model 101-2AB

[0064] Method for determining bulk density: Add the powder into a 10 mL measuring cylinder, weigh the mass of the powder in the measuring cylinder, and divide the mass by the volume to obtain the bulk density.

[0065] Method for determining the tight bulk density: Add the powder into a 10mL measuring cylinder and oscillate by continuously colliding the bottom of the measuring cylinder with the tabletop. When the height of the added powder remains unchanged after 500 collisions, weigh the mass of the powder in the measuring cylinder and divide the mass by the volume to obtain the tight bulk density.

[0066] Purity test method: Determined by high performance liquid chromatography.

[0067] Example 1

[0068] 1) 1000 g of deionized water is added to a container, and the temperature of the circulating medium is set to 100° C.; deionized water is added to 15.564 g of concentrated hydrochloric acid having a mass fraction of 36% to reach 61.202 g; 61.202 g of hydrochloric acid and 443.45 g of an aqueous solution of sodium imidazolin (the concentration of sodium imidazolin is 0.0918 g sodium imidazolin / g water) are added to the container at the same time, and the addition time is set to 2 h 51 min to obtain a suspension;

[0069] 2) Setting the temperature of the circulating medium in the container to 20°C, the suspension is cooled in the container at a rate of 0.2°C / min, and then filtered to obtain a filter cake;

[0070] 3) Wash the filter cake with deionized water and use a vacuum oven to vacuum dry at a temperature of 30°C for 18 hours; dry the obtained dry product in a blast drying oven at a temperature of 40°C for 10 hours.

[0071] 32.12 g of imidazole ethyl nicotinic acid crystals were weighed and measured to have a loose bulk density of 0.5520 g / mL and a tight bulk density of 0.6750 g / mL. The ratio A of the thickness of the crystal to the side length of the bottom crystal face was in the range of 0.2-1. The purity was 98.53%. The imidazole ethyl nicotinic acid crystals were as follows: Figure 3 shown.

[0072] Example 2

[0073] 1) 1200 g of deionized water is added to a container, and the temperature of the circulating medium is set to 95° C.; deionized water is added to 10.529 g of concentrated hydrochloric acid having a mass fraction of 36% to reach 41.404 g; 41.404 g of hydrochloric acid and 300 g of an aqueous solution of sodium imidazolin (the concentration of sodium imidazolin is 0.0923 g sodium imidazolin / g water) are added to the container at the same time, and the addition time is set to 2 h to obtain a suspension;

[0074] 2) Setting the temperature of the circulating medium in the container to 20°C, cooling the suspension in the container at a rate of 0.3°C / min, and then filtering to obtain a filter cake;

[0075] 3) Wash the filter cake with deionized water and use a vacuum oven to vacuum dry at a temperature of 30°C for 18 hours; dry the obtained dry product in a blast drying oven at a temperature of 40°C for 10 hours.

[0076] 21.83 g of imidazolin crystals were obtained by weighing. The loose bulk density of the crystals was 0.5530 g / mL, the tight bulk density was 0.7410 g / mL, the ratio A of the thickness of the crystal to the side length of the bottom crystal face was in the range of 0.2-1, and the purity was 98.34%.

[0077] Example 3

[0078] The steps are the same as those in Example 2, except that:

[0079] In step 1), the amount of deionized water is 1500 g, and the temperature of the circulating medium is set to 90°C.

[0080] 19.7 g of imidazolin crystals were obtained by weighing. The loose bulk density of the crystals was 0.5550 g / mL, the tight bulk density was 0.6850 g / mL, the ratio A of the thickness of the crystal to the side length of the bottom crystal face was in the range of 0.2-1, and the purity was 98.22%.

[0081] Example 4

[0082] 1) 1522.6 g of deionized water is added to a container, and the temperature of the circulating medium is set to 100° C.; deionized water is added to 10.172 g of concentrated hydrochloric acid having a mass fraction of 36% to reach 40 g; 40 g of hydrochloric acid and 290 g of an aqueous solution of sodium imidazolin (the concentration of sodium imidazolin is 0.0837 g sodium imidazolin / g water) are added to the container at the same time, and the addition time is set to 2 h to obtain a suspension;

[0083] 2) Setting the temperature of the circulating medium in the container to 20°C, cooling the suspension at a rate of 0.3°C / min, and then filtering to obtain a filter cake;

[0084] 3) Wash the filter cake with deionized water and use a vacuum oven to vacuum dry at a temperature of 40°C for 12 hours; dry the obtained dry product in a blast drying oven at a temperature of 50°C for 10 hours.

[0085] 19.3 g of imidazolin crystals were obtained by weighing. The loose bulk density of the crystals was 0.6044 g / mL, the tight bulk density was 0.7121 g / mL, the ratio A of the thickness of the crystal to the side length of the bottom crystal face was in the range of 0.2-1, and the purity was 98.53%.

[0086] Comparative Example 1

[0087] The steps are the same as those in Example 1, except that 58 g of deionized water is added in step 1).

[0088] 33.84 g of imidazole ethyl nicotinic acid crystals were obtained by weighing. The loose bulk density of the crystals was 0.2037 g / mL, the tight bulk density was 0.3653 g / mL, the ratio A of the thickness of the crystal to the side length of the bottom crystal face was not in the range of 0.2-1, and was less than 0.2, and the purity was 97.89%.

[0089] Comparative Example 2

[0090] The steps are the same as those in Example 1, except that in step 1), the concentration of the sodium imidazolin solution is 0.4 g sodium imidazolin / g water, and the concentration of the hydrochloric acid is 34% by weight.

[0091] 109.15 g of imidazole ethyl nicotinic acid crystals were obtained by weighing. The loose bulk density of the crystals was determined to be 0.2056 g / mL, the tight bulk density was 0.3325 g / mL, the ratio A of the thickness of the crystal to the side length of the bottom crystal face was not in the range of 0.2-1, and was less than 0.2, and the purity was 97.16%.

[0092] Comparative Example 3

[0093] The steps are the same as those in Example 1, except that in step 1), 120 g of sodium imidazolin solution is added.

[0094] 8.41 g of imidazole ethyl nicotinic acid crystals were obtained by weighing. The loose bulk density of the crystals was determined to be 0.2254 g / mL, the tight bulk density was 0.3376 g / mL, the ratio A of the thickness of the crystal to the side length of the bottom crystal face was not in the range of 0.2-1, and was less than 0.2, and the purity was 97.95%.

[0095] Comparative Example 4

[0096] Add hydrochloric acid to the imidazoline sodium solution, that is:

[0097] 1) 144.914 g of sodium imidazole ethyl nicotinate aqueous solution (the concentration of sodium imidazole ethyl nicotinate is 0.0986 g sodium imidazole ethyl nicotinate / g water) is added to a container, and the temperature of the circulating medium is set to 100° C.; deionized water is added to 5.086 g of concentrated hydrochloric acid with a mass fraction of 36% to reach 20 g; 20 g of hydrochloric acid is added to the container, and the addition time is set to 2 hours to obtain a suspension;

[0098] 2) Setting the temperature of the circulating medium in the container to 20°C, the suspension is cooled in the container at a rate of 0.2°C / min, and then filtered to obtain a filter cake;

[0099] 3) washing the filter cake with deionized water, and vacuum drying it in a vacuum oven at a drying temperature of 30° C. for 7 h; drying the obtained dried product in a blast drying oven at a drying temperature of 50° C. for 11.5 h;

[0100] 11.2 g of imidazolin crystals were weighed and obtained. The loose bulk density of the crystals was 0.2398 g / mL, the tight bulk density was 0.3081 g / mL, the ratio A of the thickness of the crystal to the side length of the bottom crystal surface was not within the range of 0.2-1, and was less than 0.2, and the purity was 97.47%. Figure 1 shown.

[0101] Comparative Example 5

[0102] Add the sodium imidazolin solution to hydrochloric acid, that is:

[0103] 1) Add deionized water to 5.086 g of concentrated hydrochloric acid with a mass fraction of 36% to make 60 g, add the 60 g of hydrochloric acid into a container, and set the temperature of the circulating medium to 100° C.; add 144.914 g of an aqueous solution of sodium imidazole ethyl nicotinate (the concentration of sodium imidazole ethyl nicotinate is 0.0986 g sodium imidazole ethyl nicotinate / g water) into the container, set the adding time to 2 h, and prepare a suspension;

[0104] 2) Setting the temperature of the circulating medium in the container to 20°C, the suspension is cooled in the container at a rate of 0.2°C / min, and then filtered to obtain a filter cake;

[0105] 3) Wash the filter cake with deionized water and use a vacuum oven to vacuum dry at a temperature of 30°C for 19.5 hours; dry the obtained dry product in a blast drying oven at a temperature of 50°C for 10 hours.

[0106] 11.0 g of imidazolin crystals were weighed and obtained. The loose bulk density of the crystals was 0.1744 g / mL, the tight bulk density was 0.2834 g / mL, the ratio A of the thickness of the crystal to the side length of the bottom crystal surface was not within the range of 0.2-1, and was less than 0.2, and the purity was 97.68%. Figure 2 shown.

[0107] Table 1

[0108]

[0109] In Table 1, the ratio A refers to the ratio of the thickness of the crystal to the side length of the bottom crystal face.

[0110] It can be seen from the results in Table 1 that when the volume ratios of water to sodium imipenem solution and the volume ratios of sodium imipenem solution to hydrochloric acid within the scope of the present invention are used, the bulk density can reach above 0.5 g / mL.

[0111] pass Figure 1 It can be seen that the imidazolin sodium crystals obtained by adding hydrochloric acid to the imidazolin sodium solution are in the form of flakes, and the specific operation is shown in Comparative Example 4; Figure 2 It can be seen that the imidazolin sodium solution is added to hydrochloric acid to obtain imidazolin crystals in the form of flakes. The specific operation is shown in Comparative Example 5. Figure 3 It can be seen that the imidazolin crystals obtained by the preparation method of the imidazolin crystals of the present invention are cubic-like, and the specific operation is shown in Example 1.

[0112] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing imidazoline crystals, characterized in that: The method comprises the following steps: 1) contacting the imidazoline sodium solution with hydrochloric acid in the presence of water to obtain a suspension; 2) cooling the suspension and performing solid-liquid separation to obtain imidazoline crystals, The volume ratio of water to sodium imidazolin solution is 0.6-6:

1. The concentration of the sodium imidazolin solution is 0.05-0.1 g sodium imidazolin / g water, the concentration of the hydrochloric acid is 5-20% by weight, and the volume ratio of the sodium imidazolin solution to the hydrochloric acid is 6-11:

1.

2. The preparation method according to claim 1, wherein The volume ratio of the sodium imidazolin solution to hydrochloric acid is 7-9:1; Preferably, the volume ratio of water to sodium imidazolin solution is 1-5:

1.

3. The preparation method according to claim 1, wherein The contact conditions include: temperature of 80-110° C. and time of 1-3 h.

4. The preparation method according to claim 1, wherein In step 2), the cooling rate is 0.1-0.5°C / min.

5. The preparation method according to claim 1, wherein The method also includes the steps of washing and drying the solid phase obtained by solid-liquid separation; Preferably, the drying includes first stage drying and second stage drying.

6. The preparation method according to claim 5, wherein: The conditions of the first stage of drying include: vacuum drying at 20-60°C for 8-24h; Preferably, the conditions for the first stage of drying include: vacuum drying at 20-40° C. for 12-24 hours.

7. The preparation method according to claim 5, wherein: The conditions of the second stage drying include: temperature of 35-60°C and time of 8-13h.

8. The preparation method according to claim 1, wherein The ratio of the thickness of the imidazolin crystal to the side length of the bottom crystal surface is 0.2-1; Preferably, based on the weight of the imidazole acetyl nicotinic acid crystals, when the amount of the imidazole acetyl nicotinic acid crystals whose ratio is not in the range of 0.2-1 is above 20 weight %, the method further comprises a grinding step.

9. The preparation method according to claim 1, wherein The bulk density of the imidazolin crystals is 0.5-0.8 g / mL.

10. A herbicide comprising the imidazolin crystals prepared by the method for preparing the imidazolin crystals according to any one of claims 1 to 9 as an active ingredient.

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