CN116063194A - Crystal form regulation and control method in glycine crystallization process - Google Patents
Crystal form regulation and control method in glycine crystallization process Download PDFInfo
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- CN116063194A CN116063194A CN202310051341.0A CN202310051341A CN116063194A CN 116063194 A CN116063194 A CN 116063194A CN 202310051341 A CN202310051341 A CN 202310051341A CN 116063194 A CN116063194 A CN 116063194A
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Abstract
The invention provides a method for regulating and controlling a crystal form in a glycine crystallization process, and relates to the technical field of crystal material preparation. The invention provides a method for regulating and controlling a crystal form in a glycine crystallization process, which comprises the following steps: heating and mixing glycine and water to obtain glycine aqueous solution; mixing the glycine aqueous solution with a salt additive to obtain a mixed solution; the mixed solution is subjected to first cooling, seed crystals are added when the temperature of a metastable zone is reduced, second cooling is carried out to a crystal growing temperature, and constant-temperature crystal growing is carried out under the condition of the crystal growing temperature, so that a solid-liquid suspension is obtained; and carrying out solid-liquid separation on the solid-liquid suspension to obtain glycine crystal products. The invention can prevent the agglomeration problem of the product caused by the transformation from the alpha crystal form to the gamma crystal form by controlling the selective generation of single crystal form glycine, and can improve the stability of the quality of glycine crystals.
Description
Technical Field
The invention relates to the technical field of crystal material preparation, in particular to a method for regulating and controlling a crystal form in a glycine crystallization process.
Background
Glycine is an important fine chemical product and has been widely used in the fields of medicine, pesticide, food, feed and the like. For further industrial processing, glycine must be in free-flowing form so that it can be easily removed from the transport vessel and processed into the machinery that produces the desired formulation. However, severe glycine agglomerates are often formed or fully agglomerated during storage and transportation, so that the glycine agglomerates must be mechanically crushed again during production to be used, and the production cost is greatly increased.
Studies have shown that control of the crystal form and particle size during glycine crystallization has a very significant impact on its storage stability. For example, patent 201611106055.6 discloses a method for controlling the granularity of glycine crystals by controlling the supersaturation degree in the nucleation process, and the technical scheme is mainly to control the granularity of the crystallized product by controlling the cooling rate. However, the method has higher requirements on equipment, small adjustable range, and can not change the crystal form of glycine, and the quality stability of the product is not easy to control.
Disclosure of Invention
The invention aims to provide a method for regulating and controlling a crystal form in a glycine crystallization process, which can prevent the agglomeration problem of a product caused by crystal form transformation in a mixed crystal product by controlling the selective generation of single crystal form glycine, has narrower crystal particle size distribution, and can improve the stability of glycine crystal quality.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for regulating and controlling a crystal form in a glycine crystallization process, which comprises the following steps:
heating and mixing glycine and water to obtain glycine aqueous solution;
mixing the glycine aqueous solution with a salt additive to obtain a mixed solution;
the mixed solution is subjected to first cooling, seed crystals are added when the temperature of a metastable zone is reduced, second cooling is carried out to a crystal growing temperature, and constant-temperature crystal growing is carried out under the condition of the crystal growing temperature, so that a solid-liquid suspension is obtained;
and carrying out solid-liquid separation on the solid-liquid suspension to obtain glycine crystal products.
Preferably, the mass ratio of glycine to water is 1:1 to 2.
Preferably, the salt additive is an inorganic salt.
Preferably, the inorganic salt comprises sodium chloride, potassium chloride, sodium nitrate, potassium nitrate or ammonium sulfate.
Preferably, the concentration of the salt additive in the mixed solution is 0.1 to 14wt%.
Preferably, the cooling rate of the first cooling is 0.05-0.2 ℃/min.
Preferably, the temperature of the metastable zone is 55-65 ℃.
Preferably, the mass of the seed crystal is 0.1-2% of the mass of glycine.
Preferably, the cooling rate of the second cooling is 0.5-1.0 ℃/min.
Preferably, the crystal growing temperature is 10-28 ℃; the constant temperature crystal growing time is 0.5-1 h.
The invention provides a method for regulating and controlling crystal forms in a glycine crystallization process, which takes glycine aqueous solution as raw material liquid, and salt additives can be selectively adsorbed on a certain glycine crystal face to change the surface energy of the crystal face to a medium so as to selectively crystallize glycine with a certain crystal form; the addition of the seed crystal is more beneficial to the nucleation of the crystal form, so that the crystallization can be controlled to be carried out in a metastable zone, the control of the nucleation of the crystallization is facilitated, and the granularity of the obtained product is uniform. The invention can generate glycine crystal products with specific crystal forms and uniform granularity, and improve the stability of glycine crystal quality. The results of the examples show that the method of the invention can obtain pure alpha-crystal form glycine or pure gamma-crystal form glycine, and the product has small and uniform particles and little caking.
Drawings
FIG. 1 is an XRD pattern of the pure gamma crystalline form of glycine product obtained in example 1;
FIG. 2 is an XRD pattern of the pure alpha crystal form glycine product obtained in example 2;
figure 3 is an XRD pattern of the alpha and gamma mixed crystal glycine product obtained in example 3.
Detailed Description
The invention provides a method for regulating and controlling a crystal form in a glycine crystallization process, which comprises the following steps:
heating and mixing glycine and water to obtain glycine aqueous solution;
mixing the glycine aqueous solution with a salt additive to obtain a mixed solution;
the mixed solution is subjected to first cooling, seed crystals are added when the temperature of a metastable zone is reduced, second cooling is carried out to a crystal growing temperature, and constant-temperature crystal growing is carried out under the condition of the crystal growing temperature, so that a solid-liquid suspension is obtained;
and carrying out solid-liquid separation on the solid-liquid suspension to obtain glycine crystal products.
The invention heats and mixes glycine and water to obtain glycine aqueous solution. In the present invention, the mass ratio of glycine to water is preferably 1:1 to 2, more preferably 1:1.5. in the present invention, the water is preferably deionized water. In the present invention, the temperature of the heated mixture is preferably 70 to 85 ℃, more preferably 80 ℃.
After the glycine aqueous solution is obtained, the glycine aqueous solution and the salt additive are mixed to obtain a mixed solution. In the present invention, the salt additive is preferably an inorganic salt. In the present invention, the inorganic salt preferably includes sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, or ammonium sulfate.
In the present invention, the concentration of the salt additive in the mixed solution is preferably 0.1 to 14wt%. In the invention, when the concentration of the salt additive is less than 3wt%, the prepared glycine crystal product is pure alpha crystal glycine; when the concentration of the salt additive is 3-7wt%, the prepared glycine crystal product is a mixture of alpha crystal form and gamma crystal form; when the concentration of the salt additive is more than 7wt%, the prepared glycine crystal product is pure gamma crystal glycine. According to the invention, a certain amount of salt additive is added, so that alpha crystals can be strongly inhibited, gamma crystals can be selectively crystallized, and when the concentration of the salt additive exceeds a critical value, the conversion from metastable crystals to stable crystals can be promoted, and pure gamma crystals of glycine can be obtained.
In the present invention, the temperature of the mixed solution is preferably 65 to 75 ℃.
After the mixed solution is obtained, the mixed solution is subjected to first cooling, seed crystals are added when the temperature of a metastable zone is reduced, second cooling is performed to a crystal growing temperature, and constant-temperature crystal growing is performed under the condition of the crystal growing temperature, so that a solid-liquid suspension is obtained.
In the present invention, the cooling rate of the first cooling is preferably 0.05 to 0.2 ℃/min, more preferably 0.1 ℃/min. In the present invention, the first cooling is preferably performed under stirring conditions; the stirring rate is preferably 200 to 800rpm, more preferably 350 to 600rpm.
In the present invention, the temperature of the metastable zone is preferably 55 to 65 ℃, more preferably 58 to 60 ℃.
In the present invention, the mass of the seed crystal is preferably 0.1 to 2% by mass of glycine, more preferably 0.5 to 1.5% by weight.
In the present invention, the cooling rate of the second cooling is preferably 0.5 to 1.0 ℃/min, more preferably 0.6 to 0.8 ℃/min.
In the invention, the crystal growing temperature is preferably 10-28 ℃, more preferably 15-25 ℃; the constant temperature crystal growing time is preferably 0.5 to 1h, more preferably 30 to 40min.
After the solid-liquid suspension is obtained, the solid-liquid separation is carried out on the solid-liquid suspension to obtain glycine crystal products. In the present invention, the solid-liquid separation is preferably suction filtration. In the invention, preferably, after the solid-liquid separation, the obtained solid substance is dried to obtain glycine crystal products. In the present invention, the drying temperature is preferably 40 to 60 ℃, more preferably 50 ℃; the drying time is preferably 6 to 24 hours, more preferably 12 hours. In the present invention, the drying is preferably performed in a vacuum environment.
In the invention, the mass ratio of the glycine crystal product with the particle size of 180-425 μm is preferably 74.04-80.68%.
On one hand, the invention utilizes the selectivity of the salt additive to the glycine polymorphic nucleation process to control the generation of single crystal glycine; on the other hand, a certain amount of seed crystals are added in the crystal form nucleation process, and the seed crystals provide more surface area for crystal growth, so that explosive nucleation is inhibited, and a product with uniform granularity is obtained.
The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
Preparing a solution with the mass ratio of glycine to deionized water of 1:2, heating to 80 ℃, keeping the temperature and fully stirring until the glycine is completely dissolved, adding sodium chloride, stirring to completely dissolve the sodium chloride, enabling the concentration of the sodium chloride in the solution to be 12wt%, slowly cooling at the cooling rate of 0.1 ℃/min under the stirring rate of 400rpm, adding gamma seed crystals with the mass of 1.0wt% of glycine when the temperature is reduced to 65 ℃, cooling to 28 ℃ at the cooling rate of 0.5 ℃/min, then carrying out constant-temperature crystal growing for 30min, carrying out vacuum pumping filtration on the obtained solid-liquid suspension, and then placing the solid-liquid suspension in a vacuum drying box at 60 ℃ for 6h to obtain pure gamma crystal glycine, wherein the product with the particle size of 180-425 mu m accounts for 78.34%.
The glycine crystal form prepared in this example was characterized and the results are shown in fig. 1.
FIG. 1 is an X-ray powder diffraction pattern of glycine prepared in example 1. The characteristic diffraction peak of the gamma-glycine crystal form is located at 2θ=25.28, and the corresponding characteristic spectral line is d= 3.520.
Example 2
Preparing a solution with the mass ratio of glycine to deionized water of 1:1.5, heating to 80 ℃, keeping the temperature and fully stirring until glycine is completely dissolved, adding sodium chloride, stirring to completely dissolve sodium chloride, enabling the concentration of sodium chloride in the solution to be 0.1wt%, starting to slowly cool at the cooling rate of 0.2 ℃/min under the stirring rate of 800rpm, adding alpha seed crystals with the mass of 0.5wt% of glycine when the temperature is reduced to 60 ℃, cooling to 10 ℃ at the cooling rate of 0.8 ℃/min, then keeping the temperature for crystal growth for 1h, filtering the obtained solid-liquid suspension by vacuum pumping, and then placing the solid-liquid suspension in a vacuum drying box at 40 ℃ for drying for 24h to obtain pure alpha crystal glycine, wherein the product mass ratio of the particle size of 180-425 mu m is 74.62%.
The glycine crystal form prepared in this example was characterized and the results are shown in fig. 2.
FIG. 2 is an X-ray powder diffraction pattern of glycine prepared in example 2. The characteristic diffraction peak of the alpha crystal form glycine is positioned at 2θ=29.78, and the corresponding characteristic spectral line is d=2.997.
Example 3
Preparing a solution with the mass ratio of glycine to deionized water of 1:2, heating to 80 ℃, keeping the temperature and fully stirring until glycine is completely dissolved, adding sodium chloride, stirring to completely dissolve sodium chloride, slowly cooling at the cooling rate of 0.05 ℃/min under the stirring rate of 600rpm, adding alpha seed crystals with the mass of 1.5% of glycine when the temperature is reduced to 60 ℃, cooling to 20 ℃ at the cooling rate of 1.0 ℃/min, then carrying out constant temperature crystal growth for 30min, filtering the obtained solid-liquid suspension by vacuum pumping, and then placing the solid-liquid suspension in a vacuum drying oven at 50 ℃ for 12h to obtain alpha and gamma mixed crystals with the mass ratio of products with the particle size of 180-425 mu m of 75.69%, wherein the mass ratio of the alpha crystal form of glycine is 31.24%.
The glycine crystal form prepared in this example was characterized and the results are shown in fig. 3.
FIG. 3 is an X-ray powder diffraction pattern of glycine prepared in example 3. Glycine has characteristic diffraction peaks at 2θ=25.28 and 2θ=29.78, respectively, and no peak is found at other positions, which proves that glycine is a mixed crystal of α and γ.
Example 4
Preparing a solution with the mass ratio of glycine to deionized water of 1:1, heating to 80 ℃, keeping the temperature and fully stirring until glycine is completely dissolved, adding potassium chloride, stirring to completely dissolve potassium chloride, slowly cooling at the cooling rate of 0.2 ℃/min under the stirring rate of 400rpm, adding gamma seed crystals with the mass of 2.0% of glycine when the temperature is reduced to 55 ℃, cooling to 10 ℃ at the cooling rate of 0.6 ℃/min, then carrying out constant-temperature crystal growth for 40min, filtering the obtained solid-liquid suspension by a vacuum pump, and then placing the solid-liquid suspension in a vacuum drying oven at 60 ℃ for 6h to obtain pure gamma crystal glycine, wherein the mass ratio of the product with the particle size of 180-425 mu m is 77.72%.
Example 5
Preparing a solution with the mass ratio of glycine to deionized water of 1:1, heating to 80 ℃, keeping the temperature and fully stirring until glycine is completely dissolved, adding potassium chloride, stirring to completely dissolve potassium chloride, enabling the concentration of potassium chloride in the solution to be 2wt%, slowly cooling at the cooling rate of 0.1 ℃/min under the stirring rate of 400rpm, adding alpha seed crystals with the mass of 2.0wt% of glycine when the temperature is reduced to 58 ℃, cooling to 10 ℃ at the cooling rate of 1.0 ℃/min, then carrying out constant-temperature crystal growing for 30min, filtering the obtained solid-liquid suspension by a vacuum pump, and then placing the solid-liquid suspension in a vacuum drying box at 60 ℃ for drying for 6h to obtain pure alpha crystal glycine, wherein the mass ratio of the product with the particle size of 180-425 mu m is 74.04%.
Example 6
Preparing a solution with the mass ratio of glycine to deionized water of 1:1.5, heating to 80 ℃, keeping the temperature and fully stirring until glycine is completely dissolved, adding potassium chloride, stirring to completely dissolve potassium chloride, enabling the concentration of potassium chloride in the solution to be 7.0wt%, slowly cooling at the cooling rate of 0.2 ℃/min under the stirring rate of 350rpm, adding alpha seed crystals with the mass of 2.0wt% of glycine when the temperature is reduced to 55 ℃, cooling to 25 ℃ at the cooling rate of 0.5 ℃/min, then carrying out constant temperature crystal growth for 30min, filtering the obtained solid-liquid suspension by vacuum pumping, and then placing the obtained solid-liquid suspension in a vacuum drying oven at 50 ℃ for 12h to obtain alpha and gamma mixed crystals, wherein the mass ratio of the product with the particle size of 180-425 μm is 74.79%, and the mass ratio of the glycine in the alpha crystal form is 8.65%.
Example 7
Preparing a solution with the mass ratio of glycine to deionized water of 1:1, heating to 80 ℃, keeping the temperature and fully stirring until glycine is completely dissolved, adding ammonium sulfate, stirring to completely dissolve the ammonium sulfate, enabling the concentration of the ammonium sulfate in the solution to be 8.5wt%, starting slow cooling at the cooling rate of 0.2 ℃/min under the stirring rate of 400rpm, adding gamma seed crystals with the mass of 2wt% of glycine when the temperature is reduced to 55 ℃, cooling to 15 ℃ at the cooling rate of 0.5 ℃/min, then carrying out constant-temperature crystal growing for 30min, filtering the obtained solid-liquid suspension by a vacuum pump, and then placing the solid-liquid suspension in a vacuum drying box at 60 ℃ for 6h to obtain pure gamma crystal glycine, wherein the mass ratio of the product with the particle size of 180-425 mu m is 80.68%.
Comparative example 1
Preparing a solution with the mass ratio of glycine to deionized water of 1:2, heating to 80 ℃, keeping the temperature constant and fully stirring until the glycine is completely dissolved, slowly cooling at the cooling rate of 0.1 ℃/min under the stirring rate of 400rpm, adding gamma seed crystals with the mass of 1.0wt% of the glycine when the temperature is reduced to 65 ℃, cooling to 10 ℃ at the cooling rate of 0.5 ℃/min, then growing crystals at the constant temperature for 30min, filtering the obtained solid-liquid suspension by a vacuum pump, and drying in a vacuum drying oven at 60 ℃ to obtain pure alpha crystal glycine, wherein the product with the particle size of 180-425 mu m accounts for 51.15%.
Comparative example 2
Preparing a solution with the mass ratio of glycine to deionized water of 1:2, heating to 80 ℃, keeping the temperature and fully stirring until glycine is completely dissolved, slowly cooling at the cooling rate of 0.2 ℃/min under the stirring rate of 400rpm, adding alpha seed crystals with the mass of 0.5wt% of glycine when the temperature is reduced to 60 ℃, cooling to 10 ℃ at the cooling rate of 0.8 ℃/min, then growing crystals at the constant temperature for 30min, filtering the obtained solid-liquid suspension by a vacuum pump, and drying in a vacuum drying oven at 60 ℃ to obtain pure alpha crystal glycine, wherein the product with the particle size of 180-425 mu m accounts for 66.25%.
Test case
The anti-coalescence properties of the glycine crystalline products prepared in examples 1 to 7 and comparative examples 1 to 2 are shown in Table 1.
TABLE 1 anti-agglomerating Properties of Glycine Crystal products
| Sample of | Initial value | After 15 days of storage | After 30 days of storage |
| Example 1 | Free flow | Free flow | Free flow |
| Example 2 | Free flow | Free flow | Free flow |
| Example 3 | Free flow | Slightly caking | Severe caking |
| Example 4 | Free flow | Free flow | Free flow |
| Example 5 | Free flow | Free flow | Free flow |
| Example 6 | Free flow | Slightly caking | Severe caking |
| Example 7 | Free flow | Free flow | Free flow |
| Comparative example 1 | Free flow | Slightly caking | Severe caking |
| Comparative example 2 | Free flow | Slightly caking | Slightly caking |
As can be seen from Table 1 and FIGS. 1 to 3, compared with comparative examples 1 to 2, the invention can obtain pure alpha or gamma crystal forms of glycine respectively under the condition of adding salt additives, the granularity distribution of the product is obviously narrowed, and the granularity distribution, crystal form, anti-agglomeration property and other quality indexes of glycine products can be effectively improved.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A method for regulating and controlling a crystal form in a glycine crystallization process, which comprises the following steps:
heating and mixing glycine and water to obtain glycine aqueous solution;
mixing the glycine aqueous solution with a salt additive to obtain a mixed solution;
the mixed solution is subjected to first cooling, seed crystals are added when the temperature of a metastable zone is reduced, second cooling is carried out to a crystal growing temperature, and constant-temperature crystal growing is carried out under the condition of the crystal growing temperature, so that a solid-liquid suspension is obtained;
and carrying out solid-liquid separation on the solid-liquid suspension to obtain glycine crystal products.
2. The method according to claim 1, wherein the mass ratio of glycine to water is 1:1 to 2.
3. The method of claim 1, wherein the salt additive is an inorganic salt.
4. A method according to claim 3, wherein the inorganic salt comprises sodium chloride, potassium chloride, sodium nitrate, potassium nitrate or ammonium sulphate.
5. A method according to claim 1 or 3, characterized in that the concentration of the salt additive in the mixed solution is 0.1-14 wt%.
6. The method of claim 1, wherein the first cooling rate is between 0.05 and 0.2 ℃/min.
7. The method of claim 1, wherein the metastable zone has a temperature of 55 to 65 ℃.
8. The method according to claim 1, wherein the mass of the seed crystal is 0.1 to 2% of the mass of glycine.
9. The method of claim 1, wherein the second cooling rate is between 0.5 and 1.0 ℃/min.
10. The method of claim 1, wherein the seeding temperature is 10-28 ℃; the constant temperature crystal growing time is 0.5-1 h.
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