Method for converting betaine powder into hexagonal crystals with sweet smell

Abstract

The invention relates to a method for converting betaine powder into hexagonal crystals with sweet smell, which adopts a phase inversion-differential dissolution method. Adding betaine powder into a crystallizer, adding a mixed solution of ethanol and water as a solvent, heating to 70-85 DEG C, and cooling to room temperature; filtering is not performed temporarily after cooling, betaine powder is added into the crystallizer again, heating is performed to enable the betaine powder to be dissolved, and then cooling is performed to room temperature; and repeating the heating and cooling operations, filtering the crystal slurry after the last cooling, washing the crystal with ethanol, and drying the crystal, thereby obtaining the hexagonal anhydrous betaine crystal product emitting sweet smell. The method has the advantages of simplicity, high efficiency, energy conservation and feasibility, and is an optimal method for improving the quality and the production efficiency of the betaine product at present.

Description

Technical Field

[0001] The present application relates to a method for crystallizing anhydrous betaine, and in particular to a method for producing a new anhydrous betaine crystal product. Background Art

[0002] Betaine is a compound with a quaternary ammonium salt or ammonium structure, and is a derivative of glycine. The molecular structure of natural betaine is the simplest. The chemical name of this substance is trimethylamine betaine, which means that three methyl groups replace the three hydrogen atoms on the nitrogen atom of glycine. The molecular formula is C5H11NO2, the molecular weight is 117.15, and the structural formula is as follows Betaine is widely found in animals and plants. It is an intermediate product of metabolism in animals and plays a very important role in the process of cell metabolism. According to the molecular structure of betaine, the molecule contains both anions and cations. The presence of polar groups makes it very soluble in water. At 20°C, the solubility of betaine in water is about 153 g / 100 g water. For this reason, betaine solid has a strong hygroscopic capacity and is very easy to deliquesce. Betaine particles can quickly absorb water vapor in the air and become liquid when exposed to air with high humidity. Therefore, strict moisture-proof measures are required during the storage and transportation of betaine. In the betaine molecule, the presence of non-polar groups makes it have an affinity with oil and dirt. Although there are weak acid radicals in the molecule, the ability to hydrolyze is greatly weakened by the adjacent positively charged nitrogen atoms, making the betaine aqueous solution neutral, which also makes betaine an excellent skin cleanser. Because betaine has the characteristics of water retention and does not harm the skin, it is also often used in skin care products. The strong binding force of betaine with water enables it to retain cell moisture and maintain osmotic pressure, which can enhance the stress resistance and salt-alkali tolerance of crops in arid areas. The carboxylate group present in the betaine molecule also has the ability to receive protons, which makes betaine useful for neutralizing gastric acid and treating related diseases. Betaine molecules can also be a source of methyl in cell synthesis, which can provide biological functions equivalent to some of methionine. This enables it to promote protein synthesis, thereby increasing the production of products such as meat, eggs, milk and amino acids produced by bacterial fermentation. As a natural ingredient extracted from beets or sugarcane, betaine also has a sweet taste, and there is no risk of blood sugar rising when it is consumed. Therefore, using betaine as a food additive will be beneficial to human health. Therefore, betaine is a multifunctional product.

[0003] Betaine is widely used and its annual consumption is huge. In the past few years, the annual consumption in China alone has reached more than 200,000 tons. Betaine extracted from plants such as sugarcane or beets can no longer meet the demand. Now most betaine products are produced by synthesis. However, there are impurities in the synthesized betaine, which limits its application. Although it has been legalized in food in the United States and Europe, it is not allowed in China and can only be used as a feed additive. Crystallization has a purification effect, which can significantly reduce the impurities and improve the purity and quality of the product. Therefore, it is particularly important to develop a crystallization method for betaine, especially anhydrous betaine. Betaine molecules have a strong binding force with water molecules, and the crystals usually obtained by crystallization from water are monohydrates. The content of betaine in this product is only 86.68%, and the 13.32% of water cannot provide nutrition. The presence of water reduces the nutritional value of betaine crystal products, so when used as food additives, it is expected that the crystals do not contain water. The monohydrate crystals are heated at 110-120°C, and anhydrous betaine can be obtained by removing bound water. However, the dehydrated crystals are no longer transparent, but become white opaque particles, which no longer have the characteristics of crystals. Due to the departure of bound water molecules, cracks and gaps are generated in the particles, and the chemical properties become unstable. Although the disclosed decomposition temperature is as high as 293°C, in fact, a trace decomposition reaction occurs during the drying process, so that the betaine product can decompose and release trimethylamine at room temperature. The substance has a strong and unpleasant amine smell, and even a small amount of release will still be smelled and perceived immediately, thereby reducing the quality and value of the product. When used as a food additive, it is not desirable to have any odor, so anhydrous betaine crystals can only be obtained directly by crystallization to eliminate the odor.

[0004] The nutritional value of anhydrous betaine is higher than that of monohydrate betaine, and the production and sale of anhydrous betaine products is the future development direction. However, the anhydrous betaine products produced by the dehydration method of monohydrate betaine have obvious quality defects, which makes the production of anhydrous betaine products by crystallization method have huge market potential. In order to ensure that the obtained crystals are water-free, water cannot be used as a solvent in the crystallization process. However, for betaine, the types of solvents available are limited. From its molecular structure, it can be seen that this is a highly polar molecule, so the solvent that can dissolve it must have a strong polarity. In addition to water, the boiling points of other highly polar solvents are very high, which not only produces side reactions but also increases costs. In addition, other low-boiling point solvents such as methanol are toxic and harmful to the human body, and washing and drying cannot completely remove them. The presence of residual solvents brings certain risks to food safety. In order to enable anhydrous betaine crystal products to be safely used as food additives, the most ideal solvent is ethanol. However, as the polarity of water, methanol and ethanol molecules decreases successively, the solubility of betaine in them gradually decreases. At 20°C, the solubility of betaine has been reduced to 8 g / 100 g ethanol, which is less than one-tenth of its solubility in water. The reduction in solubility directly leads to a reduction in crystallization yield, reducing the economic benefits of anhydrous betaine crystal products. When ethanol is used as a solvent, the yield is very low regardless of whether evaporation crystallization or cooling crystallization is used. At 78°C, the solubility of betaine in ethanol only rises to 24 g / 100 g ethanol, which is still much lower than its solubility in water. This means that only 24 g of anhydrous betaine crystal product can be obtained for every 100 g of ethanol evaporated, with high costs such as energy consumption and time, and low yield and efficiency; and when cooled to 20°C, only 16 g of crystal product can be obtained for every 100 g of ethanol, and the yield is also low. The low yield is an inherent defect of the crystallization method using ethanol as a solvent, which seriously hinders the widespread application of this product.

[0005] For betaine crystal products, the shape of the crystal is also an important factor affecting the quality of the crystal product. The shape of the crystal is determined by the betaine molecule itself and the crystallization conditions. Anhydrous betaine crystals are usually flaky crystals with a thin thickness, which is not conducive to the flow of crystal particles. This directly leads to a decrease in the bulk density, which is generally 0.5~0.6 g / mL, and the highest does not exceed 0.7 g / mL. In addition, the thin flaky anhydrous betaine is very easy to break, which affects the appearance and particle size of the crystal product, thereby reducing the quality of the product. Although the monohydrate betaine crystals no longer have the characteristics of flaky and full particles, their crystals will swell during the dehydration process, thereby reducing the bulk density. As a food additive, people expect the particles to have good fluidity and high bulk density. Therefore, developing a crystallization method for anhydrous betaine and changing the crystal morphology to make it have good fluidity are also a major problem that needs to be solved at present. In addition, the uniformity of the crystal product is also an important feature. Although they undergo the same crystallization process in the crystallizer and the shapes of the crystals are very similar, their sizes are not exactly the same, but show a certain distribution. This means that in the same batch of anhydrous betaine crystal products, there are both crystals of several millimeters in size and crystals of several microns in size. The unevenness of particle size not only affects the appearance, but also reduces the bulk density, thereby reducing the quality of the crystal product. In the same crystallization process, all crystal particles have the same size under ideal conditions, but this is impossible. In fact, it is only possible to make the crystal particles in a certain particle size range a little more, so as to improve the quality of the crystal product as much as possible. As long as the particle size range is narrow enough and the number of crystals in it is large enough, the particle size distribution of the crystal product will be more concentrated, thereby ensuring uniform particle size. In order to achieve this, the existing crystallization method is to add crystal seeds with uniform particle size to the crystallizer, but this strategy also adds more operating steps to the crystallization process, thereby increasing the difficulty. This is because when adding crystal seeds, the lid of the crystallizer needs to be opened, and a large amount of ethanol vapor will overflow, which poses a potential safety risk. The existence of these problems seriously restricts the development of anhydrous betaine crystal product technology.

[0006] From the above practical issues such as the properties and needs of betaine crystals, we can see that the nutritional value of anhydrous betaine crystal products is higher than that of monohydrate betaine products, and the stability is also higher than that of anhydrous betaine products produced by dehydration of the latter, and it does not release odor, so the production of anhydrous betaine crystals is the future development trend of this product. However, the current method of using ethanol as a solvent to produce anhydrous betaine still has technical problems to be solved, such as improving efficiency, changing shape, controlling particle size, and simplifying processes. How to simply and efficiently produce high-quality anhydrous betaine crystal products is a problem that needs to be solved urgently. Summary of the invention

[0007] In view of the above actual conditions and difficulties, the crystallization method in this application is proposed. This method uses betaine powder as raw material, and uses harmless solvent ethanol as the solvent for crystallization, and the product produced is anhydrous betaine crystals. It not only solves the problems of puffing, whitening of particles and release of odor of the original anhydrous betaine products, but also has higher purity and bulk density of the crystal products, and more concentrated particle size distribution. More importantly, the method in this application has lower crystallization and drying temperatures and lower energy consumption, which increases the value of the crystal products while reducing production costs, so that the crystal products have a wide range of application prospects. This application not only absorbs the advantages of the previous development of anhydrous betaine crystal products, but also proposes a new crystallization method-phase transformation-differential dissolution method. This method is simpler and more efficient, not only improves product quality and production efficiency, but also develops a new betaine crystal product. This product not only has the advantages of previous anhydrous betaine crystal products, but also can release a sweet smell and show a new and unique hexagon, which has huge market potential.

[0008] Phase inversion method This method belongs to the transformation process between solid phases and involves the liquid-solid equilibrium state of physicochemistry. The synthesis of betaine is carried out in an aqueous solution, and the extraction of the product from the aqueous solution must be dehydrated. The resulting solid is in an unstable state that is not combined with a solvent. When this raw material is in ethanol, when the unstable solid phase disappears, new crystals that can remain stable with the solution are formed, thereby having the morphology of the crystal. However, the shape of the crystal does not depend on the state of the solution. The two bottoms of the crystals obtained by crystallization from ethanol in the previous method are both rhombuses, while the two bottoms of the crystals of the present application are hexagonal. This is a method similar to suspension crystallization, the difference being that not only the crystal form is transformed, but also the crystal shape is changed and is not unique. The advantage of this method is that the crystallization raw material can be transformed in the same crystallization system, and the disadvantage is that the number of crystals cannot be controlled.

[0009] Differential Dissolution This method involves the difference in dissolution rate between particles and the liquid-solid non-equilibrium state of physicochemistry. The specific surface area of ​​particles of different sizes is different, which directly leads to differences in dissolution rates. Smaller particles have a larger specific surface area and a faster dissolution rate. In addition, small particles are smaller in volume and will be consumed first and disappear during dissolution, reducing the number of crystals in the crystallization system, while larger particles are retained. When dissolving, they do not follow the law of crystallization, and the corners and edges are dissolved faster to form a shape similar to pebbles. Compared with spontaneously nucleated nuclei, the size of these particles is obviously much larger. When crystallizing, they continue to follow the law of crystallization, and the betaine molecules in the solution continue to stack and assemble based on them, thereby forming new larger crystals with more uniform particle size. The advantage of this method is that it replaces the step of adding seeds, which is simpler and safer. The disadvantage is that its effect is greatly affected by solubility.

[0010] The method of the present application comprehensively utilizes the advantages of the above two methods and overcomes their disadvantages, thereby obtaining a new method that is more suitable for the production of anhydrous betaine crystal products.

[0011] The operation steps of the phase inversion-differential dissolution method in the present invention include the following three steps: 1) Add a mixed solution of ethanol and water as a solvent to a crystallizer, then add betaine powder, with a mass ratio of betaine:solvent = 5-13:20, raise the temperature to 70-85°C in 0-0.5 h, keep the temperature constant for 0-4 h, condense the generated steam and reflux to the crystallizer, and then cool to 20-30°C in 0.5-7 h; 2) The betaine powder added to the crystallizer again is 0-0.30 of the mass of the solvent in step 1), and then the temperature is repeatedly raised and lowered 0-19 times according to the method of step 1); 3) After the last cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, quickly remove the ethanol under closed conditions, and then vacuum dry the crystals in an oven at 20-100°C to obtain a hexagonal anhydrous betaine crystal product with a bulk density of 0.6-0.7 g / mL. The generated mother liquor, washing liquid and condensate are returned to step 1) for repeated use.

[0012] Specific operating conditions of the above three steps In step 1), in the mixed solution of ethanol and water, the mass fraction of ethanol is 95-100 wt%.

[0013] In step 1), the mass ratio of betaine powder to solvent is in the range of 5 to 13:20, preferably 5 to 10:20.

[0014] In step 1), the heating time has no significant effect on the quality of the crystal product and is generally 0 to 0.5 h.

[0015] In step 1), the temperature range reached by heating is 70-85°C, preferably 78-85°C.

[0016] In step 1), the time range of maintaining the constant temperature after heating is 0 to 4 h, preferably 0 to 0.5 h.

[0017] In step 1), the steam generated during the crystallization process is condensed and refluxed, and tap water can be used as condensed water.

[0018] In step 1), the cooling time ranges from 0.5 to 7 h, preferably from 1 to 4 h.

[0019] In step 1), the temperature range of cooling is 20-30°C, preferably 25-30°C.

[0020] In step 2), the mass range of the added betaine powder is 0-0.30 of the mass of the solvent in step 1), preferably 0-0.20.

[0021] In step 2), the temperature rise and fall are repeated 0 to 19 times, preferably 2 to 8 times.

[0022] In step 3), the filtration method has a significant effect on the residual amount, and centrifugal filtration is preferred.

[0023] In step 3), after filtering, soak and wash with ethanol, usually twice, and it should be completed quickly. In step 3), the filtration device must be sealed during filtration to prevent water vapor from being adsorbed on the crystal surface.

[0024] In step 3), the mother liquor and washing liquid obtained by filtration can be used in step 1).

[0025] In step 3), the crystal product is first dried at 20-30°C, and then the temperature is raised to 30-100°C for drying after the ethanol on the surface of the crystal evaporates.

[0026] In step 3), the drying method can be air drying or vacuum drying, and vacuum drying is preferred.

[0027] In step 3), the ethanol vapor produced by the vacuum drying method is condensed and can be used in step 1).

[0028] In step 3), the anhydrous betaine crystals emit a sweet smell, are colorless and transparent, and have two hexagonal bottom surfaces, two of which have an angle of 82.5°±1° relative to each other, and the remaining four angles are 138.5°±1°.

[0029] The method of the present application is used to obtain the crystals as shown in the attached Figures 1 to 3As shown in the figure, it can be seen that the bottom surface of the crystal is a hexagon, characterized by two relative angles of 82.5°±1°, the remaining four angles of 138.5°±1°, and the thickness direction is perpendicular to the bottom surface. Figure 4 The bulk density of the crystals ranges from 0.600 to 0.700 g / mL, and the mass proportion of crystal particles with a particle size distribution of 20 to 60 mesh ranges from 90.0 to 100.0 wt%. The test conditions for X-ray powder diffraction are Cu Kα / 40 kV / 100 mA, the diffraction 2θ angle ranges from 2 to 52°, the diffraction rate is 8° / min, and the crystals are not ground. The 2θ angles of the characteristic diffraction peaks with a relative intensity greater than 20% are 12.0°±0.5°, 19.5°±0.5°, 24.3°±0.5°, 36.9°±0.5°, and 50.0°±0.5°. The XRD spectrum is shown in the attached figure. Figure 5 The comparison of the anhydrous betaine crystal product obtained by the crystallization method of the present application, the previous anhydrous betaine crystal product and the commercially available anhydrous betaine crystal product is shown in Table 1.

[0030] Table 1 Comparison of the anhydrous betaine crystals in this application, the previous anhydrous betaine crystals and the commercially available anhydrous betaine crystals In summary, the crystallization method of the present application combines the advantages of the phase conversion method and the differential dissolution method to overcome their shortcomings, thereby developing an anhydrous betaine crystal product with new characteristics. The method has the advantages of simplicity, high efficiency, energy saving and environmental protection, thereby significantly reducing production costs. The anhydrous betaine crystal product not only retains the advantages of existing anhydrous betaine crystal products, but also has new crystal characteristics. Higher product value and lower cost will significantly increase profit margins, thereby obtaining more output value. These advantages fully demonstrate the highlights of the method of the present application, making it feasible to put it into production practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attached Figure 1 The acute angles in the hexagonal base of the anhydrous betaine crystals of the present application Attached Figure 2 An obtuse angle in the hexagonal bottom of the anhydrous betaine crystal of the present application Attached Figure 3 Another obtuse angle in the hexagonal bottom surface of the anhydrous betaine crystal of the present application Attached Figure 4 SEM image of anhydrous betaine crystals obtained by the crystallization method of the present application Attached Figure 5 XRD spectrum of anhydrous betaine crystals obtained by the crystallization method of the present application DETAILED DESCRIPTION

[0032] The present invention is further illustrated by the following examples, but is not intended to limit the present invention.

[0033] Implementation Case 1 Add 40.50 g of betaine powder and 150.46 g of ethanol to the crystallizer, with the mass ratio of betaine powder to solvent being 27:100. Set the stirring speed to 300 r / min, and raise the circulating water temperature to 85.2°C within 15 min to dissolve the betaine powder. Then keep the temperature constant for 0.5 h, and the generated steam is condensed through the condensation straight tube and refluxed to the crystallizer. The cooling medium is tap water. Then cool to 30°C within 4 h.

[0034] 20.79 g of betaine powder was added to the crystallizer again, and the betaine powder accounted for 0.14 of the mass of the solvent. The circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condensation straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 4 h. The temperature rise and fall was repeated twice.

[0035] After cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, then quickly soak and wash twice with n-hexane, seal the Buchner funnel with plastic wrap, and intermittently and slowly filter to remove n-hexane. First, put the Buchner funnel in a vacuum oven at 20°C to dry for 1 hour, and then put it in a blast drying oven at 70°C to dry for 10 hours. A sweet smell can be smelled from the top of the dried crystals. The purity of the obtained anhydrous betaine crystals is 99.8%, the bulk density is 0.675 g / mL, and the mass proportion of 20~60 mesh is 92.70 wt%.

[0036] Implementation Case 2 Add 49.18 g of betaine powder and 150.51 g of ethanol to the crystallizer, with a mass ratio of betaine powder to solvent of 33:100. Set the stirring speed to 300 r / min, and raise the circulating water temperature to 85.2°C within 15 min to dissolve the betaine powder. Then keep the temperature constant for 0.5 h, and the generated steam is condensed through the condensation straight tube and refluxed to the crystallizer. The cooling medium is tap water. Then cool to 30°C within 4 h.

[0037] 0 g of betaine powder was added to the crystallizer again, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condenser straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 4 h. The temperature was raised and lowered twice. After cooling, 29.56 g of betaine powder was added to the crystallizer again. The betaine powder was 0.20 of the solvent mass, and the temperature was raised and lowered three times.

[0038] After cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, then quickly soak and wash twice with n-hexane, seal the Buchner funnel with plastic wrap, and intermittently and slowly filter to remove n-hexane. First, put the Buchner funnel in a vacuum oven at 20°C to dry for 1 hour, and then put it in a blast drying oven at 70°C to dry for 10 hours. A sweet smell can be smelled from the top of the dried crystals. The purity of the obtained anhydrous betaine crystals is 99.6%, the bulk density is 0.649 g / mL, and the mass proportion of 20~60 mesh is 95.29 wt%.

[0039] Implementation Case 3 Add 76.86 g of betaine powder and 150.00 g of ethanol to the crystallizer, with a mass ratio of betaine powder to solvent of 51:100. Set the stirring speed to 300 r / min, and raise the circulating water temperature to 85.2°C within 15 min to dissolve the betaine powder. Then keep the temperature constant for 0.5 h, and the generated steam is condensed through the condensation straight tube and refluxed to the crystallizer. The cooling medium is tap water. Then cool to 30°C within 4 h.

[0040] 0 g of betaine powder was added to the crystallizer again, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condenser straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 4 h. The temperature rise and fall was repeated 8 times.

[0041] After cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, then quickly soak and wash twice with n-hexane, seal the Buchner funnel with plastic wrap, and intermittently and slowly filter to remove n-hexane. First, put the Buchner funnel in a vacuum oven at 20°C to dry for 1 hour, and then put it in a blast drying oven at 70°C to dry for 10 hours. A sweet smell can be smelled from the top of the dried crystals. The purity of the obtained anhydrous betaine crystals is 99.4%, the bulk density is 0.665 g / mL, and the mass proportion of 20~60 mesh is 90.76 wt%.

[0042] Implementation Case 4 78.70 g of betaine powder and 150.03 g of ethanol were added to the crystallizer, with the mass ratio of betaine powder to solvent being 13:25. The stirring speed was set to 300 r / min, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. The temperature was then kept constant for 0.5 h, and the generated steam was condensed through a condensing straight tube and refluxed to the crystallizer. The cooling medium was tap water. The temperature was then lowered to 30°C within 4 h.

[0043] 0 g of betaine powder was added to the crystallizer again, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condenser straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 4 h. The temperature rise and fall was repeated 11 times.

[0044] After cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, then quickly soak and wash twice with n-hexane, seal the Buchner funnel with plastic wrap, and intermittently and slowly filter to remove n-hexane. First, put the Buchner funnel in a vacuum oven at 20°C to dry for 1 hour, and then put it in a blast drying oven at 70°C to dry for 10 hours. A sweet smell can be smelled from the top of the dried crystals. The purity of the obtained anhydrous betaine crystals is 99.0%, the bulk density is 0.664 g / mL, and the mass proportion of 20~60 mesh is 93.54 wt%.

[0045] Implementation Case 5 Add 99.00 g of betaine powder and 150.13 g of ethanol to the crystallizer, with a mass ratio of betaine powder to solvent of 33:50. Set the stirring speed to 300 r / min, and raise the circulating water temperature to 85.2°C within 15 min to dissolve the betaine powder. Then keep the temperature constant for 0.5 h, and the generated steam is condensed through the condensation straight tube and refluxed to the crystallizer. The cooling medium is tap water. Then cool to 30°C within 4 h.

[0046] 0 g of betaine powder was added to the crystallizer again, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condenser straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 4 h. The temperature rise and fall was repeated 11 times.

[0047] After cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, then quickly soak and wash twice with n-hexane, seal the Buchner funnel with plastic wrap, and intermittently and slowly filter to remove n-hexane. First, put the Buchner funnel in a vacuum oven at 20°C to dry for 1 hour, and then put it in a blast drying oven at 70°C to dry for 10 hours. A sweet smell can be smelled from the top of the dried crystals. The purity of the obtained anhydrous betaine crystals is 99.2%, the bulk density is 0.640 g / mL, and the mass proportion of 20~60 mesh is 94.81 wt%.

[0048] Implementation Case 6 Add 80.15 g of betaine powder and 150.42 g of ethanol to the crystallizer, with a mass ratio of betaine powder to solvent of 53:100. Set the stirring speed to 300 r / min, and raise the circulating water temperature to 80.8°C within 15 min to dissolve the betaine powder. Then keep the temperature constant for 0.5 h, and the generated steam is condensed through the condensation straight tube and refluxed to the crystallizer. The cooling medium is tap water. Then cool to 30°C within 4 h.

[0049] 0 g of betaine powder was added to the crystallizer again, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condenser straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 4 h. The temperature rise and fall was repeated 11 times.

[0050] After cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, then quickly soak and wash twice with n-hexane, seal the Buchner funnel with plastic wrap, and intermittently and slowly filter to remove n-hexane. First, put the Buchner funnel in a vacuum oven at 20°C to dry for 1 hour, and then put it in a blast drying oven at 70°C to dry for 10 hours. A sweet smell can be smelled from the top of the dried crystals. The purity of the obtained anhydrous betaine crystals is 99.6%, the bulk density is 0.622 g / mL, and the mass proportion of 20~60 mesh is 92.12 wt%.

[0051] Implementation Case 7 80.50 g of betaine powder and 150.55 g of ethanol-water solution with a water content of 2 wt% were added to the crystallizer, and the mass ratio of betaine powder to solvent was 53:100. The stirring speed was set to 300 r / min, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condensing straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 4 h.

[0052] 0 g of betaine powder was added to the crystallizer again, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condenser straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 4 h. The temperature rise and fall was repeated 8 times.

[0053] After cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, then quickly soak and wash twice with n-hexane, seal the Buchner funnel with plastic wrap, and intermittently and slowly filter to remove n-hexane. First, put the Buchner funnel in a vacuum oven at 20°C and dry it for 1 h, then put it in a blast drying oven at 70°C and dry it for 10 h. A sweet smell can be smelled from the top of the dried crystals. The purity of the obtained anhydrous betaine crystals is 99.0%, the bulk density is 0.673 g / mL, and the mass proportion of 20~60 mesh is 92.83 wt%.

[0054] Implementation Case 8 Add 79.18 g of betaine powder and 150.05 g of ethanol to the crystallizer, with a mass ratio of betaine powder to solvent of 53:100. Set the stirring speed to 300 r / min, and raise the circulating water temperature to 85.2°C within 15 min to dissolve the betaine powder. Then keep the temperature constant for 0.5 h, and the generated steam is condensed through the condensation straight tube and refluxed to the crystallizer. The cooling medium is tap water. Then cool to 30°C within 2 h.

[0055] 0 g of betaine powder was added to the crystallizer again, and the circulating water was heated to 85.2°C within 15 min to dissolve the betaine powder. Then the temperature was kept constant for 0.5 h, and the generated steam was condensed through a condenser straight tube and refluxed to the crystallizer. The cooling medium was tap water. Then the temperature was lowered to 30°C within 2 h. The temperature rise and fall was repeated 8 times.

[0056] After cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, then quickly soak and wash twice with n-hexane, seal the Buchner funnel with plastic wrap, and intermittently and slowly filter to remove n-hexane. First, put the Buchner funnel in a vacuum oven at 20°C and dry it for 1 hour, and then put it in a blast drying oven at 70°C and dry it for 10 hours. A sweet smell can be smelled from the top of the dried crystals. The purity of the obtained anhydrous betaine crystals is 99.5%, the bulk density is 0.647 g / mL, and the mass proportion of 20~60 mesh is 95.14 wt%.

[0057] The technical solutions proposed and disclosed in the present invention can be realized by those skilled in the art by referring to the contents of this article and appropriately changing the conditions, routes and other links. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, relevant technicians can obviously modify or re-combine the methods and technical routes described herein without departing from the content, spirit and scope of the present invention to realize the final preparation technology. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all deemed to be included in the spirit, scope and content of the present invention.

Claims

1. A method for converting betaine powder into hexagonal crystals with a sweet smell, characterized in that: The phase inversion-differential dissolution method comprises the following steps: 1) Add a mixed solution of ethanol and water as a solvent to a crystallizer, then add betaine powder, with a mass ratio of betaine:solvent = 5-13:20, raise the temperature to 70-85°C in 0-0.5 h, keep the temperature constant for 0-4 h, condense the generated steam and reflux to the crystallizer, and then cool to 20-30°C in 0.5-7 h; 2) The betaine powder added to the crystallizer again is 0-0.30 of the mass of the solvent in step 1), and then the temperature is repeatedly raised and lowered 0-19 times according to the method of step 1); 3) After the last cooling, filter the crystal slurry, quickly soak and wash the crystals twice with ethanol, quickly remove the ethanol under closed conditions, and then vacuum dry the crystals in an oven at 20-100°C to obtain a hexagonal anhydrous betaine crystal product with a bulk density of 0.6-0.7 g / mL. The generated mother liquor, washing liquid and condensate are returned to step 1) for repeated use.

2. The method according to claim 1, characterized in that In step 1), in the mixed solution of ethanol and water, the mass fraction of ethanol is 95-100 wt%.

3. The method according to claim 1, characterized in that In step 1), the mass ratio of betaine powder to solvent is in the range of 5 to 10:

20.

4. The method according to claim 1, characterized in that In step 1), the temperature range reached by heating is 78~85°C.

5. The method according to claim 1, characterized in that In step 1), the time range of constant temperature after heating is 0~0.5 h.

6. The method according to claim 1, characterized in that In step 1), the cooling time ranges from 1 to 4 h.

7. The method according to claim 1, characterized in that In step 1), the temperature range of cooling is 25~30°C.

8. The method according to claim 1, characterized in that In step 2), the mass range of the added betaine powder is 0 to 0.20 of the mass of the solvent in step 1).

9. The method according to claim 1, characterized in that In step 2), the temperature rise and fall are repeated 2 to 8 times.

10. The method according to claim 1, characterized in that In step 3), the anhydrous betaine crystals emit a sweet smell and have a shape of two hexagonal bottom surfaces, two of which have an angle of 82.5°±1° relative to each other, and the remaining four angles are 138.5°±1°.

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