Glycine chelated magnesium and preparation method thereof

Abstract

The invention relates to the technical field of nutritional supplements, in particular to glycine chelated magnesium and a preparation method thereof.The preparation method includes the steps of raw material preparation, raw material dissolution, chelation reaction, separation, purification, crystallization and drying treatment. The pH value of the reaction system is regulated in the whole process, the product is prepared through seed crystal induced crystallization, the chelation reaction efficiency and the product purity are effectively improved, the production process is simplified, and the method is suitable for large-scale production. The high-purity stable glycine chelated magnesium can be efficiently prepared, the process is simple and easy to control, the production cost is low, the water solubility and bioavailability of the product are excellent, and the method is suitable for application in multiple fields.

Description

Technical Field

[0001] This invention relates to the field of nutritional supplement technology, specifically to a glycine chelated magnesium and its preparation method. Background Technology

[0002] Magnesium is an essential macromineral element for the human body, widely involved in hundreds of enzymatic reactions, energy metabolism, neuromuscular excitability regulation, cellular ion balance maintenance, bone mineralization and growth, and other core physiological processes. It is an indispensable nutrient for maintaining normal physiological functions. Insufficient intake in traditional diets and abnormal physiological metabolism can easily lead to magnesium deficiency in the human body, which in turn can cause dysfunction in multiple systems such as the nervous, cardiovascular, and skeletal systems. Therefore, the development of safe and effective magnesium supplements has always been a research hotspot in the food and pharmaceutical fields.

[0003] Most commercially available magnesium supplements are inorganic magnesium salts such as magnesium oxide, magnesium hydroxide, and magnesium carbonate. These products generally suffer from poor water solubility, low absorption efficiency, and insufficient bioavailability. Furthermore, oral administration can easily irritate the gastrointestinal tract, causing discomfort such as bloating and diarrhea, significantly limiting their application. Glycine chelated magnesium, as a third-generation amino acid chelate mineral supplement, forms a stable double five-membered ring chelate structure with glycine through coordination bonds. It combines the advantages of good water solubility, chemical stability, no gastrointestinal irritation, and easy absorption and utilization by the human body, making it an ideal magnesium fortifier with wide applications in functional foods, health products, and pharmaceutical preparations.

[0004] Existing technologies for preparing glycine-chelated magnesium still have many shortcomings: conventional aqueous solution synthesis methods have low chelation reaction efficiency, high content of free glycine and free magnesium ions in the product, insufficient chelation rate, and easy formation of non-chelated complex salts, which seriously affect product purity and bioavailability; some processes introduce organic phases to construct biphase reaction systems to improve chelation effect, which not only significantly increases production costs but also brings the risk of solvent residue and cumbersome separation and purification processes, making it difficult to achieve large-scale production; in addition, solid-phase synthesis, microwave-assisted processes have problems such as poor reaction uniformity, high equipment requirements, and insufficient product stability, making it impossible to balance product quality and production economy, which seriously restricts the large-scale production and market application of high-quality glycine-chelated magnesium. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a glycine chelated magnesium and its preparation method.

[0006] (II) Technical Solution A method for preparing glycine-chelated magnesium includes the following steps: S1 Raw material preparation: Weigh out glycine and inorganic magnesium source according to the molar ratio of glycine to magnesium ions in the magnesium source of 2.0:1 to 2.5:1, and weigh out chelation promoter at the same time. The amount of chelation promoter used is 0.5% to 2.0% of the mass of glycine. S2 raw material dissolution: Add the weighed glycine to deionized water and stir until completely dissolved to obtain glycine aqueous solution; add the inorganic magnesium source to deionized water and stir to prepare magnesium source slurry, or directly use the inorganic magnesium source for later use; S3 chelation reaction: Under stirring, the magnesium source slurry is added to the glycine aqueous solution in batches, or the inorganic magnesium source is added directly to the glycine aqueous solution in batches, and all chelation promoters are added simultaneously. The pH of the reaction system is adjusted and controlled to 5.5~6.5 throughout the process. The temperature is raised to 60~80℃, and the reaction is stirred and kept at this temperature for 2~4 hours to obtain the chelation reaction solution. S4 Separation, Purification and Crystallization: The chelation reaction solution is filtered while hot to remove unreacted substances. The resulting filtrate is concentrated under vacuum to 1 / 3 to 1 / 5 of its original volume. Glycine-chelated magnesium crystals are added to the concentrate. After standing for crystallization for 1 to 2 hours, the solution is filtered and the crystalline precipitate is collected. S5 Drying treatment: The crystalline precipitate was placed in a vacuum drying oven and dried to obtain glycine chelated magnesium product; The chelation promoter is an organic acid compound with a molecular structure similar to glycine, and its aqueous solution has an ionization constant of 10⁻⁵ to 10⁻².

[0007] Preferably, the inorganic magnesium source in step S1 is one or more of magnesium oxide, magnesium hydroxide, and magnesium carbonate.

[0008] Preferably, in step S1, the molar ratio of glycine to magnesium ions in the magnesium source is 2.2:1.

[0009] Preferably, the chelation promoter is selected from one or more of acetic acid, monochloroacetic acid, and dichloroacetic acid.

[0010] Preferably, the amount of chelation promoter used in step S1 is 0.5% to 1.0% of the mass of glycine.

[0011] Preferably, in step S3, the reaction system is heated to 60-70°C and stirred for 2-3 hours.

[0012] Preferably, in step S3, a chelation promoter is used to simultaneously adjust the pH value of the reaction system, maintaining the pH value of the system within the range of 5.5 to 6.5 throughout the process.

[0013] Preferably, the vacuum concentration in step S4 is carried out by reduced pressure low-temperature evaporation concentration.

[0014] Preferably, in step S5, the vacuum drying temperature is 50~70℃ and the drying time is 4~8 hours.

[0015] Preferably, the glycine chelated magnesium prepared using the above-described method is a white, free-flowing crystalline powder with the molecular formula Mg(C2H4NO2)2·nH2O, where n is 0-4; the product has a purity ≥98% on a dry basis, a chelation rate ≥90%, a magnesium element mass fraction of 12.5%-13.5%, and an infrared spectrum in the range of 1575-1641 cm⁻¹. -1 and 1380~1420 cm -1 The characteristic absorption peak at this location indicates a carboxylate chelate structure.

[0016] (iii) Beneficial technical effects Compared with existing technologies, the beneficial effects of this invention are: Using organic acid compounds with molecular structures similar to glycine as chelation promoters can effectively reduce the activation energy of the chelation reaction, significantly improve the efficiency and selectivity of the chelation reaction, induce glycine and magnesium ions to form a stable double five-membered ring chelate structure, avoid the generation of byproducts such as non-chelated complex salts, and ensure the stability and uniformity of the product chelate structure from the source of the reaction.

[0017] The reaction system is an all-aqueous reaction system, with no organic solvents introduced throughout the process, completely avoiding the risk of solvent residue. At the same time, it greatly simplifies the production process and separation and purification procedures, reducing production energy consumption and raw material costs. The reaction conditions are mild, the process parameters are highly controllable, and no complex production equipment is required, making it easy to achieve continuous industrial-scale production and possessing excellent production economics.

[0018] The resulting glycine-chelated magnesium product has high purity and low content of free impurities. It exhibits excellent water solubility and long-term storage stability, and is a free-flowing powder that can meet the processing and application needs of various scenarios such as food, health products, and pharmaceutical preparations. At the same time, the product is non-irritating to the gastrointestinal tract and has superior human absorption efficiency and bioavailability compared to traditional inorganic magnesium salts and non-chelated magnesium salts. It can safely and efficiently achieve the nutritional supplementation of magnesium and has broad market application prospects. Attached Figure Description

[0019] Figure 1 This is a flowchart of a method for preparing glycine-chelated magnesium disclosed in this invention; Figure 2 This is the infrared spectrum of glycine chelated magnesium from Example 1; Figure 3 This is the infrared spectrum of glycine chelated magnesium in Example 2; Figure 4 This is the infrared spectrum of glycine chelated magnesium in Example 3; Figure 5 The infrared spectrum of the glycine-magnesium oxide blend in Comparative Example 6 is shown below. Figure 6 This is the infrared spectrum of magnesium glycine salt in Comparative Example 7. Detailed Implementation

[0020] according to Figures 1 to 6 The specific embodiments of the present invention are as follows: This specific embodiment details the glycine chelated magnesium protected by the present invention and its preparation method. All operations comply with the hygiene standards for the production of food-grade and pharmaceutical-grade raw materials. All raw materials used are of food-grade or pharmaceutical-grade purity, and all equipment used is conventional industrial equipment, requiring no special customized devices.

[0021] The complete operation process and detailed control requirements for the glycine-chelated magnesium preparation method of the present invention are as follows: The first step is the preparation of raw materials (S1). The core raw materials used in this step include three categories: glycine, inorganic magnesium source, and chelation promoter. L-glycine is selected, with a purity of not less than 99% and free of visible impurities. The inorganic magnesium source is any one or a combination of magnesium oxide, magnesium hydroxide, and magnesium carbonate, with the effective MgO content of magnesium oxide not less than 93%, the effective Mg(OH)2 content of magnesium hydroxide not less than 95%, and the effective MgCO3 content of magnesium carbonate not less than 98%. All magnesium sources are powdered materials that have passed through a 100-mesh sieve to ensure uniform dispersion during the reaction. The chelation promoter is an organic acid compound with a molecular structure similar to glycine, and its aqueous solution must have a stable ionization constant of 10. -5 ~10 -2 Within the specified range, any one or more combinations of acetic acid, monochloroacetic acid, and dichloroacetic acid can be used. These organic acids can reduce the activation energy of the chelation reaction through a synergistic effect with the molecular structure of glycine, and directionally induce the amino nitrogen atom and carbonyl oxygen atom of glycine to form a stable double five-membered ring chelate structure with magnesium ions. When weighing the raw materials, the molar ratio of glycine to magnesium ions in the magnesium source should be controlled within the range of 2.0:1 to 2.5:1, preferably 2.2:1. This ratio can provide sufficient coordination groups for magnesium ions, avoiding the hydrolysis and precipitation of magnesium ions, and can also prevent excessive glycine from causing the free glycine content in the product to exceed the standard. The weighing mass of the chelation promoter is 0.5% to 2.0% of the mass of glycine, preferably 0.5% to 1.0%. This dosage range can achieve the optimal chelation promotion effect without introducing detectable residual impurities into the product, ensuring the food and pharmaceutical safety of the product.

[0022] Next is the S2 raw material dissolution step. The weighed glycine is added to deionized water, with the amount of deionized water being 5-8 times the mass of the glycine. At room temperature, the mixture is stirred continuously at a speed of 150-200 rpm for 10-15 minutes until the glycine is completely dissolved, resulting in a clear, transparent glycine aqueous solution free of visible insoluble matter. The pretreatment of the inorganic magnesium source can be carried out in two ways depending on the material characteristics: The first is pulping. The weighed inorganic magnesium source is added to deionized water, with the amount of deionized water being 10-15 times the mass of the magnesium source. The mixture is stirred continuously at a speed of 200-250 rpm for 5-10 minutes to prepare a uniformly dispersed, clumpy magnesium source slurry. This method avoids excessively high local concentrations of the magnesium source when directly added, which can lead to drastic pH fluctuations in the reaction system and the generation of byproducts. The second method is direct addition. For powdered magnesium sources with excellent dispersibility and no clumping, they can be directly sealed and stored for later use without prior pulping, further simplifying the production process.

[0023] Next is the S3 chelation reaction stage, which is carried out in a reactor equipped with a constant temperature heating jacket, an online pH monitor, a mechanical stirrer, and a sealed feeding port. First, all the prepared glycine aqueous solution is transferred to the reactor, and the mechanical stirrer is turned on and the speed is stably controlled at 180~220 r / min. Then, the magnesium source slurry is slowly added to the reactor in batches at a constant flow rate. If the direct feeding method is used, the magnesium source powder is added to the reactor in 3~5 equal batches, with an interval of 5~8 min between each batch to ensure that the magnesium source is uniformly dispersed in the system and to avoid excessively high local magnesium ion concentrations. After the magnesium source is fed, immediately add all the weighed chelation accelerator to the reaction system. Adjust the initial pH value of the system by using the acidity of the chelation accelerator. At the same time, a small amount of food-grade 10% sodium hydroxide solution or 10% dilute hydrochloric acid can be added to precisely adjust the pH value of the system to the target range of 5.5~6.5. Then turn on the constant temperature heating jacket and heat the reaction system to 60~80℃, preferably 60~70℃. Maintain the stirring speed at 180~220r / min throughout the process and keep the reaction at this temperature for 2~4 hours, preferably 2~3 hours. During the reaction, the pH value of the system was read every 30 minutes using an online pH monitor. If the pH value deviated from the set range of 5.5 to 6.5, it was finely adjusted in time with a small amount of chelation promoter or dilute alkaline solution to ensure that the pH value remained stable within the target range throughout the reaction. This pH range can ensure that the amino and carboxyl groups of glycine are in the optimal coordination activity state, avoid the hydrolysis of magnesium ions to form magnesium hydroxide precipitate, and maximize the synergistic induction effect of the chelation promoter, ensuring that the chelation reaction proceeds efficiently and in a targeted manner, and reducing the formation of by-products.

[0024] The next step is the S4 separation, purification, and crystallization process. After the chelation reaction is complete, heating is stopped, and stirring is maintained. The reaction solution is then filtered while hot at 60-70°C using a 0.45μm precision filter membrane to remove any unreacted magnesium source residue and insoluble impurities, resulting in a clear and transparent chelation reaction filtrate. The filtrate is then transferred to a vacuum concentration vessel and concentrated using a low-temperature evaporation method. The vacuum level inside the concentration vessel is controlled at -0.08 to -0.1 MPa, and the material temperature is maintained at 55-65°C to prevent product structure damage from high temperatures. Concentration is stopped when the filtrate volume is reduced to 1 / 3 to 1 / 5 of its original volume, yielding a high-concentration glycine-chelated magnesium concentrate. Transfer the concentrate to a clean crystallization vessel, start low-speed stirring (50-80 rpm), and add glycine chelated magnesium seed crystals (pre-filtered through a 200-mesh sieve) to the concentrate at room temperature. The amount of seed crystals added is 0.1%-0.3% of the concentrate mass. Immediately stop stirring after adding the seed crystals, seal the crystallization vessel, and let it stand for 1-2 hours to allow the glycine chelated magnesium to fully precipitate and form uniformly sized crystalline particles. After crystallization, filter the crystalline material, collect the precipitate, and remove any residual trace soluble impurities from the filtrate to further improve the purity of the product.

[0025] Finally, in the S5 drying process, the collected crystalline precipitate is evenly spread on the tray of the vacuum drying oven, with the thickness controlled at 1-2 cm to avoid uneven drying and localized excessive moisture content due to excessive thickness. The door of the vacuum drying oven is closed, and a vacuum is drawn until the vacuum degree inside the oven stabilizes at -0.08 to -0.1 MPa. The drying temperature is set at 50-70℃, and drying is continued for 4-8 hours. During this period, the moisture content of the material is checked every 2 hours until the moisture content of the product is ≤1.0%, at which point drying is stopped. After the temperature inside the vacuum drying oven naturally drops to room temperature, the vacuum is broken, the dried product is taken out, crushed, and passed through an 80-mesh standard sieve to obtain a white, free-flowing crystalline powder of glycine chelated magnesium.

[0026] The glycine-chelated magnesium product obtained by the above method has the molecular formula Mg(C2H4NO2)2·nH2O, where n is 0~4. The product has a purity ≥98% on a dry basis, a chelation rate ≥90%, and a magnesium element mass fraction of 12.5%~13.5%. Infrared spectroscopy analysis shows that the magnesium content is within the range of 1575~1641 cm⁻¹. -1 and 1380~1420 cm -1 The characteristic absorption peak of the carboxylate chelate structure is significantly shifted compared to the infrared characteristic peak of free glycine, confirming the formation of a stable chelate structure.

[0027] The technical solution of the present invention will be further described in detail below through specific embodiments:

[0028] Example 1 In this embodiment, magnesium oxide is used as the inorganic magnesium source, and acetic acid is used as the chelation promoter. The preparation is carried out using the preferred process parameters of this invention, and the specific operation is as follows: 1. Raw material preparation: Weigh out food-grade L-glycine and food-grade light magnesium oxide according to a molar ratio of glycine to magnesium ions in the magnesium source of 2.2:1; weigh out acetic acid as a chelation promoter at 0.8% of the mass of glycine, using an aqueous solution of acetic acid with an ionization constant of 1.8 × 10⁻⁶. -5 ; 2. Raw material dissolution: Add the weighed glycine to 6 times its weight of deionized water, and stir at 180 r / min for 12 min at room temperature until the glycine is completely dissolved to obtain a clear glycine aqueous solution; add the weighed magnesium oxide to 12 times its weight of deionized water, and stir at 220 r / min for 8 min to prepare a uniformly dispersed magnesium oxide slurry without clumping; 3. Chelation reaction: Glycine aqueous solution was added to a reaction vessel equipped with a constant temperature jacket and an online pH monitor. Stirring was started and the speed was kept stable at 200 r / min. Magnesium oxide slurry was slowly added dropwise to the reaction vessel at a constant flow rate. After the addition was complete, all acetic acid was added to the reaction system, and the pH value of the system was adjusted to 6.0±0.2. The constant temperature heating was started, and the system temperature was raised to 70℃. The stirring speed was maintained at 200 r / min throughout the process, and the reaction was carried out at this temperature for 2 hours. The pH value was monitored every 30 minutes during the reaction, and fine-tuned with a small amount of acetic acid or 10% sodium hydroxide solution to ensure that the pH value remained stable between 5.8 and 6.2 throughout the process. 4. Separation, purification, and crystallization: After the reaction is complete, heating is stopped, stirring is maintained, and the mixture is filtered hot through a 0.45μm filter membrane at 65℃ to remove a small amount of insoluble residue, resulting in a clear filtrate. The filtrate is transferred to a vacuum concentration apparatus, and the vacuum degree is controlled at -0.09MPa and the temperature at 60℃. The mixture is concentrated to 1 / 4 of its original volume to obtain a concentrated glycine chelated magnesium solution. The concentrated solution is transferred to a crystallization container and stirred at a low speed of 60r / min. Glycine chelated magnesium crystals that have passed through a 200-mesh sieve are added, with the amount of crystals added being 0.2% of the mass of the concentrated solution. After the addition is complete, stirring is stopped, and the container is sealed and allowed to stand for crystallization for 1.5 hours. The mixture is then filtered, and the white crystalline precipitate is collected. 5. Drying treatment: Spread the crystalline precipitate evenly on the tray of the vacuum drying oven with a thickness of 1.5cm. Control the vacuum degree to -0.09MPa and the drying temperature to 65℃. Continue drying for 6 hours. When the moisture content of the material is ≤1.0%, stop drying, cool to room temperature, take it out, and crush it through an 80-mesh sieve to obtain a white, free-flowing crystalline powder of glycine chelated magnesium.

[0029] Example 2 In this embodiment, magnesium carbonate was selected as the inorganic magnesium source, and dichloroacetic acid was used as the chelation promoter. The preparation was carried out within the lower limit range of the process parameters of this invention. The specific operation is as follows: 1. Raw material preparation: Weigh out food-grade L-glycine and food-grade magnesium carbonate according to a molar ratio of glycine to magnesium ions in the magnesium source of 2.0:1; weigh out dichloroacetic acid as a chelation promoter at 0.5% of the mass of glycine, using an aqueous solution of dichloroacetic acid with an ionization constant of 5.0 × 10⁻⁶. -2 ; 2. Raw material dissolution: Add the weighed glycine to 6 times its weight of deionized water, and stir at 150 r / min for 15 min at room temperature until the glycine is completely dissolved to obtain a clear glycine aqueous solution; add the weighed magnesium carbonate to 10 times its weight of deionized water, and stir at 200 r / min for 10 min to prepare a uniformly dispersed magnesium carbonate slurry. 3. Chelation reaction: Add glycine aqueous solution to the reaction vessel, start stirring, and stabilize the speed at 180 r / min. Slowly add magnesium carbonate slurry to the reaction vessel at a constant flow rate. After the addition is complete, add all dichloroacetic acid to the reaction system, adjust the pH value of the system to 5.6±0.1, start constant temperature heating, and raise the temperature of the system to 60℃. Maintain the stirring speed at 180 r / min throughout the process and keep the reaction at this temperature for 3 hours. Monitor the pH value every 30 minutes during the reaction to ensure that the pH value remains stable between 5.5 and 5.8 throughout the process. 4. Separation, purification, and crystallization: After the reaction is complete, heating is stopped, stirring is maintained, and the mixture is filtered hot through a 0.45μm filter membrane at 60℃ to remove insoluble residues and obtain a clear filtrate. The filtrate is transferred to a vacuum concentration apparatus, and the vacuum degree is controlled at -0.085MPa and the temperature at 55℃. The mixture is concentrated to 1 / 3 of its original volume to obtain a concentrated glycine chelated magnesium solution. The concentrated solution is transferred to a crystallization container and stirred at a low speed of 50r / min. Glycine chelated magnesium crystals that have passed through a 200-mesh sieve are added at a concentration of 0.1% of the concentrated solution mass. After the addition is complete, stirring is stopped, the container is sealed, and allowed to stand for crystallization for 2 hours. The mixture is then filtered, and the white crystalline precipitate is collected. 5. Drying treatment: Spread the crystalline precipitate evenly on the tray of the vacuum drying oven with a thickness of 1cm. Control the vacuum degree to -0.085MPa and the drying temperature to 50℃. Continue drying for 8 hours. When the moisture content of the material is ≤1.0%, stop drying, cool to room temperature, take it out, and crush it through an 80-mesh sieve to obtain a white, free-flowing crystalline powder of glycine chelated magnesium.

[0030] Example 3 In this embodiment, magnesium hydroxide was selected as the inorganic magnesium source, and monochloroacetic acid was used as the chelation promoter. The preparation was carried out within the upper limit range of the process parameters of this invention. The specific operation is as follows: 1. Raw material preparation: Weigh out food-grade L-glycine and food-grade magnesium hydroxide according to a molar ratio of glycine to magnesium ions in the magnesium source of 2.5:1; weigh out monochloroacetic acid as a chelation promoter at 2.0% of the mass of glycine, with an aqueous solution ionization constant of 1.4 × 10⁻⁶. -3 ; 2. Raw material dissolution: Add the weighed glycine to 7 times its weight of deionized water, and stir at 200 r / min for 10 min at room temperature until the glycine is completely dissolved to obtain a clear glycine aqueous solution; magnesium hydroxide is a highly dispersible powder, which can be directly sealed for use without pre-slurrying. 3. Chelation reaction: Add glycine aqueous solution to the reaction vessel, start stirring, and stabilize the speed at 220 r / min. Add magnesium hydroxide powder in 4 equal batches, with an interval of 6 min between each batch. After the addition is complete, add all the monochloroacetic acid to the reaction system, adjust the pH value of the system to 6.3±0.2, start the constant temperature heating, and raise the temperature of the system to 80℃. Maintain the stirring speed at 220 r / min throughout the process and keep the reaction at this temperature for 4 hours. Monitor the pH value every 30 min during the reaction to ensure that the pH value remains stable between 6.2 and 6.5 throughout the process. 4. Separation, purification, and crystallization: After the reaction is complete, heating is stopped, stirring is maintained, and the mixture is filtered hot through a 0.45μm filter membrane at 70℃ to remove a small amount of insoluble residue, resulting in a clear filtrate. The filtrate is transferred to a vacuum concentration apparatus, and the vacuum degree is controlled at -0.1MPa and the temperature at 65℃. The mixture is concentrated to 1 / 5 of its original volume to obtain a concentrated glycine chelated magnesium solution. The concentrated solution is transferred to a crystallization container and stirred at a low speed of 80r / min. Glycine chelated magnesium crystals that have passed through a 200-mesh sieve are added, with the amount of crystals added being 0.3% of the mass of the concentrated solution. After the addition is complete, stirring is stopped, and the mixture is sealed and allowed to stand for crystallization for 1 hour. The mixture is then filtered, and the white crystalline precipitate is collected. 5. Drying treatment: Spread the crystalline precipitate evenly on the tray of the vacuum drying oven with a thickness of 2cm. Control the vacuum degree to -0.1MPa and the drying temperature to 70℃. Continue drying for 4 hours. When the moisture content of the material is ≤1.0%, stop drying, cool to room temperature, take it out, and crush it through an 80-mesh sieve to obtain a white, free-flowing crystalline powder of glycine chelated magnesium.

[0031] Example 4 In this embodiment, a mixed magnesium source of magnesium oxide and magnesium carbonate, and a mixed chelation promoter of acetic acid and monochloroacetic acid were used for preparation. The specific operation is as follows: 1. Raw material preparation: Weigh food-grade L-glycine and a mixed magnesium source according to a glycine-to-magnesium ion molar ratio of 2.2:1, where the magnesium ion molar ratio of magnesium oxide to magnesium carbonate in the mixed magnesium source is 1:1; weigh a mixed chelation accelerator at 1.0% of the glycine mass, where the mass ratio of acetic acid to monochloroacetic acid in the mixed chelation accelerator is 1:1, and the ionization constant of the aqueous solution of the mixed chelation accelerator is within 10. -5 ~10 -2 Within the range; 2. Raw material dissolution: Add the weighed glycine to 6 times its weight of deionized water, and stir at 180 r / min for 12 min at room temperature until the glycine is completely dissolved to obtain a clear glycine aqueous solution; add the mixed magnesium source to 12 times its weight of deionized water, and stir at 220 r / min for 8 min to prepare a uniformly dispersed mixed magnesium source slurry. 3. Chelation reaction: Add glycine aqueous solution to the reactor, start stirring, and stabilize the speed at 200 r / min. Slowly add the mixed magnesium source slurry to the reactor at a constant flow rate. After the addition is complete, add all the mixed chelation promoter to the reaction system, adjust the pH value of the system to 6.0±0.3, start the constant temperature heating, and raise the temperature of the system to 65℃. Maintain the stirring speed at 200 r / min throughout the process and keep the reaction at this temperature for 2.5 hours. Monitor the pH value every 30 minutes during the reaction to ensure that the pH value remains stable between 5.7 and 6.3 throughout the process. 4. Separation, purification, and crystallization: After the reaction is complete, heating is stopped, stirring is maintained, and the mixture is filtered hot through a 0.45μm filter membrane at 65℃ to remove insoluble residues and obtain a clear filtrate. The filtrate is transferred to a vacuum concentration apparatus, and the vacuum degree is controlled at -0.09MPa and the temperature at 60℃. The mixture is concentrated to 1 / 4 of its original volume to obtain a concentrated glycine chelated magnesium solution. The concentrated solution is transferred to a crystallization container and stirred at a low speed of 60r / min. Glycine chelated magnesium crystals that have passed through a 200-mesh sieve are added at a rate of 0.2% of the mass of the concentrated solution. After the addition is complete, stirring is stopped, the container is sealed, and the mixture is allowed to stand for crystallization for 1.5 hours. The mixture is then filtered, and the white crystalline precipitate is collected. 5. Drying treatment: Spread the crystalline precipitate evenly on the tray of the vacuum drying oven with a thickness of 1.5cm. Control the vacuum degree to -0.09MPa and the drying temperature to 60℃. Continue drying for 7 hours. When the moisture content of the material is ≤1.0%, stop drying, cool to room temperature, take it out, and crush it through an 80-mesh sieve to obtain a white, free-flowing crystalline powder of glycine chelated magnesium.

[0032] The following comparative examples are set up to verify the necessity and technical advantages of the various technical features of the present invention by comparing them with Example 1. Except for the parameters that are explicitly adjusted, all other raw materials, equipment and operating procedures in the comparative examples are completely consistent with those in Example 1: Comparative Example 1 This comparative example does not add any chelation promoter, and the rest of the operation is completely consistent with Example 1. Specifically, the chelation promoter is not weighed in the raw material preparation stage, and the pH value of the system is adjusted to 5.8~6.2 by 10% dilute hydrochloric acid and sodium hydroxide solution in the chelation reaction stage. The remaining steps and parameters are the same as in Example 1, and a white powder product is finally obtained.

[0033] Comparative Example 2 This comparative example does not control the pH value throughout the reaction process, but only adjusts the initial pH value. The rest of the operation is completely consistent with Example 1. Specifically, in the chelation reaction step, the initial pH value is adjusted to 6.0 only after the material is fed. No pH monitoring or fine-tuning is performed during the reaction. The rest of the steps and parameters are the same as in Example 1. Finally, a white powder product is obtained.

[0034] Comparative Example 3 In this comparative example, the molar ratio of glycine to magnesium ions was adjusted to 1.8:1, which is lower than the lower limit specified in this invention. The remaining operations were completely consistent with those in Example 1. Specifically, in the raw material preparation step, the raw materials were weighed according to the molar ratio of glycine to magnesium ions of 1.8:1. The remaining steps and parameters were the same as in Example 1, and a white powder product was finally obtained.

[0035] Comparative Example 4 The comparative example adjusted the reaction temperature to 50°C and the reaction time to 1 hour, which is lower than the parameter range specified in this invention. The remaining operations are completely consistent with Example 1. Specifically, the chelation reaction step is heated to 50°C and stirred for 1 hour. The remaining steps and parameters are the same as in Example 1, and a white powder product is finally obtained.

[0036] Comparative Example 5 In this comparative example, no glycine chelated magnesium crystals were added during the crystallization process. Natural static crystallization was used, and the rest of the operation was completely consistent with Example 1. Specifically, after the concentrate was transferred to the crystallization container, no crystals were added, and the container was directly sealed and allowed to stand for crystallization for 1.5 hours. All other steps and parameters were the same as in Example 1, and a white powder product was finally obtained.

[0037] Comparative Example 6 This comparative example is a physical mixture of glycine and magnesium oxide. The specific operation is as follows: according to the same raw material ratio as in Example 1, glycine and magnesium oxide are weighed, placed in a clean mortar, and ground thoroughly until they are mixed evenly to obtain a white powdery physical mixture, which serves as the control sample.

[0038] Comparative Example 7 This comparative example is a simple double salt product without chelation promoter. The specific operation is as follows: according to the same raw material ratio as in Example 1, glycine and magnesium oxide are weighed and added to sufficient deionized water. No chelation promoter is added and the pH value of the reaction process is not controlled. The reaction is stirred at 60°C for 1 hour. After the reaction is completed, it is directly concentrated and dried to obtain a white solid product, which serves as the control sample.

[0039] The products obtained in the above embodiments and comparative examples were subjected to infrared spectroscopy detection and performance verification, and the results are as follows: The infrared spectra of the products obtained in Examples 1-3 correspond to the following, respectively. Figure 2 , Figure 3 , Figure 4 All are between 1575 and 1641 cm -1 and 1380~1420 cm -1 The product exhibits a distinct absorption peak characteristic of the carboxylate chelate structure, which shifts significantly compared to the characteristic peak of free glycine, confirming that the product has formed a stable double five-membered ring chelate structure. The product purity and chelation rate are in line with expectations, and it has excellent water solubility with no obvious impurities.

[0040] The infrared spectrum of the physical mixture in Comparative Example 6 corresponds to... Figure 5 Spectral characteristics superimposed on the spectra of glycine and magnesium oxide raw materials Figure 1 The characteristic shift of the chelate structure was not observed, confirming that a coordination chelate structure was not formed; the infrared spectrum of the simple complex salt product of Comparative Example 7 corresponds to... Figure 6 Only the basic characteristic peaks of α-amino acids were observed, and no shift of the characteristic absorption peaks of the chelate structure was observed, confirming that an effective chelate structure was not formed.

[0041] The core chelation performance and purity of the products from the examples and comparative examples are compared in the table below: Table 1 Sample number Chelation rate (%) Dry basis purity (%) Mass fraction of magnesium (%) Free glycine content (%) Free magnesium ion content (%) Example 1 94.5 98.7 13.0 0.28 0.18 Example 2 93.4 98.2 12.9 0.32 0.22 Example 3 92.5 98.1 12.8 0.36 0.24 Example 4 93.8 98.4 12.9 0.30 0.20 Comparative Example 1 61.2 84.7 11.2 3.42 4.15 Comparative Example 2 54.6 79.8 10.5 4.18 5.42 Comparative Example 3 70.8 87.6 14.1 2.76 3.58 Comparative Example 4 65.7 85.8 11.5 3.18 3.95 Comparative Example 5 79.6 91.8 12.7 1.18 0.78 Comparative Example 6 4.2 / 8.6 48.2 9.80 Comparative Example 7 11.8 69.7 10.8 42.3 8.45 The application performance and stability indicators of the examples and comparative examples are compared in the table below: Table 2 Sample number Dissolution rate of simulated gastrointestinal fluid in vitro for 30 minutes (%) Angle of repose of powder (°) Accelerated stability test chelation rate and retention rate (%) Complete dissolution time (s) for 1% concentration Example 1 95.8 33 98.2 50 Example 2 94.6 34 97.5 55 Example 3 94.2 35 97.3 56 Example 4 95.3 33 98.0 52 Comparative Example 1 71.5 43 81.6 135 Comparative Example 2 64.8 46 74.2 165 Comparative Example 3 77.6 41 84.5 115 Comparative Example 4 69.2 44 79.3 145 Comparative Example 5 84.7 39 89.6 90 Comparative Example 6 34.2 50 / 360 Comparative Example 7 41.5 48 59.2 255 As shown in Tables 1 and 2, the glycine-chelated magnesium products of Examples 1-4 prepared using the optimized process of this invention achieve high standards in core chelation performance, dry basis purity, and free impurity control. Furthermore, they exhibit excellent performance in in vitro gastrointestinal fluid dissolution efficiency, powder flowability, water solubility, and accelerated storage stability, with all key indicators significantly superior to those of the comparative examples. The outstanding performance of these examples fully demonstrates the core technical features of this invention, including synergistic chelation promoter action, precise pH control throughout the process, optimized glycine-magnesium molar ratio, isothermal-controlled chelation reaction, and seed-induced crystallization. These features enable efficient and directional chelation reactions, fundamentally improving product quality and application suitability.

[0042] The comparative examples, due to the absence of key process steps and deviation of process parameters from the protection range, showed a significant decline in product chelation efficiency and purity, a surge in free impurity content, and a marked deterioration in application performance. The physical mixtures and simple complex salts did not form a stable chelated structure and were completely devoid of application value as chelated magnesium supplements, further confirming the necessity, advancement, and practicality of the technical solution of this invention.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing glycine-chelated magnesium, characterized in that, Includes the following steps: S1 Raw material preparation: Weigh out glycine and inorganic magnesium source according to the molar ratio of glycine to magnesium ions in the magnesium source of 2.0:1 to 2.5:1, and weigh out chelation promoter at the same time. The amount of chelation promoter used is 0.5% to 2.0% of the mass of glycine. S2 raw material dissolution: Add the weighed glycine to deionized water and stir until completely dissolved to obtain glycine aqueous solution; add the inorganic magnesium source to deionized water and stir to prepare magnesium source slurry, or directly use the inorganic magnesium source for later use; S3 chelation reaction: Under stirring, the magnesium source slurry is added to the glycine aqueous solution in batches, or the inorganic magnesium source is added directly to the glycine aqueous solution in batches, and all chelation promoters are added simultaneously. The pH of the reaction system is adjusted and controlled to 5.5~6.5 throughout the process. The temperature is raised to 60~80℃, and the reaction is stirred and kept at this temperature for 2~4 hours to obtain the chelation reaction solution. S4 Separation, Purification and Crystallization: The chelation reaction solution is filtered while hot to remove unreacted substances. The resulting filtrate is concentrated under vacuum to 1 / 3 to 1 / 5 of its original volume. Glycine-chelated magnesium crystals are added to the concentrate. After standing for crystallization for 1 to 2 hours, the solution is filtered and the crystalline precipitate is collected. S5 Drying treatment: The crystalline precipitate was placed in a vacuum drying oven and dried to obtain glycine chelated magnesium product; The chelation promoter is an organic acid compound with a molecular structure similar to glycine, and its aqueous solution has an ionization constant of 10. -5 ~10 -2 .

2. The method for preparing glycine-chelated magnesium according to claim 1, characterized in that, The inorganic magnesium source in step S1 is one or more of magnesium oxide, magnesium hydroxide, and magnesium carbonate.

3. The method for preparing glycine-chelated magnesium according to claim 1, characterized in that, In step S1, the molar ratio of glycine to magnesium ions in the magnesium source is 2.2:

1.

4. The method for preparing glycine-chelated magnesium according to claim 1, characterized in that, The chelation promoter is selected from one or more of acetic acid, monochloroacetic acid, and dichloroacetic acid.

5. The method for preparing glycine-chelated magnesium according to claim 1, characterized in that, In step S1, the amount of chelation promoter used is 0.5% to 1.0% of the mass of glycine.

6. The method for preparing glycine-chelated magnesium according to claim 1, characterized in that, In step S3, the reaction system is heated to 60-70°C and stirred for 2-3 hours.

7. The method for preparing glycine-chelated magnesium according to claim 1, characterized in that, In step S3, a chelation promoter is used to simultaneously adjust the pH value of the reaction system, maintaining the pH value of the system within the range of 5.5 to 6.5 throughout the process.

8. The method for preparing glycine-chelated magnesium according to claim 1, characterized in that, The vacuum concentration in step S4 is carried out using a reduced-pressure, low-temperature evaporation concentration method.

9. The method for preparing glycine-chelated magnesium according to claim 1, characterized in that, In step S5, the vacuum drying temperature is 50~70℃ and the drying time is 4~8 hours.

10. A glycine-chelated magnesium prepared by the method according to any one of claims 1-9, characterized in that, The glycine-chelated magnesium is a white, free-flowing crystalline powder with the molecular formula Mg(C2H4NO2)2·nH2O, where n is 0~4. The product has a purity ≥98% on a dry basis, a chelation rate ≥90%, a magnesium element mass fraction of 12.5%~13.5%, and an infrared spectrum in the range of 1575~1641 cm⁻¹. -1 and 1380~1420 cm -1 The characteristic absorption peak at this location indicates a carboxylate chelate structure.

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