A method for preparing high-purity glycine

Abstract

The present invention relates to the technical field of glycine preparation, and proposes a method for preparing high-purity glycine, comprising the following steps: S1, using monoethanolamine and water as reaction raw materials, reacting under the action of a catalyst, filtering to obtain glycine salt, acidifying the glycine salt, concentrating to obtain a crude glycine product; S2, recrystallizing the crude glycine product to obtain high-purity glycine; the catalyst is a heavy metal modified molecular sieve. Through the above technical scheme, the problems of low yield and low purity of glycine prepared in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of glycine preparation, and in particular to a method for preparing high-purity glycine. Background Art

[0002] Glycine, as the simplest amino acid, has extremely wide applications in many fields such as chemical industry, medicine, food, and feed. In the chemical industry, glycine is an important organic synthesis intermediate and participates in the synthesis of a variety of fine chemicals; in the pharmaceutical field, glycine can be used in the synthesis of pharmaceutical preparations and plays a role in some drugs for the treatment of liver diseases, muscle diseases, etc.; in the food industry, it is used as a flavoring agent and nutritional supplement; in the feed industry, glycine can promote animal growth and development.

[0003] At present, the production processes of glycine mainly include chloroacetic acid ammonolysis, direct hydantoin process, biological process, etc. Chloroacetic acid ammonolysis is a relatively traditional and widely used production method. Its principle is that chloroacetic acid reacts with ammonia under alkaline conditions to produce glycine. However, this process has many disadvantages, and the production cost is high due to the relatively expensive price of chloroacetic acid and the large amount of raw materials such as ammonia required during the reaction process. The direct hydantoin process uses hydroxyacetonitrile as a raw material to produce glycine under certain reaction conditions. This process has the significant advantage of low production cost, can effectively reduce the cost of raw materials, and can better solve the problem of difficult transportation of hydrocyanic acid. It has good development potential, but its application and popularity in China are still relatively limited. The biological method for preparing glycine is to synthesize glycine using biocatalysts such as microorganisms or enzymes. This process has the advantages of green environmental protection and mild reaction conditions, which is in line with the current concept of sustainable development. However, at this stage, the biological method is still in the stage of technical development and improvement, and it is still facing a series of technical challenges such as the difficulty in controlling the activity and stability of biocatalysts, low reaction efficiency, and high production costs. It has not yet achieved large-scale industrial production and application.

[0004] With increasingly stringent environmental protection requirements and the increasing market demand for high-quality glycine, improvement and innovation of the existing glycine production process is imminent. The current glycine preparation method still has problems of low yield and low purity. Therefore, it is very important to develop a method for preparing high-yield and high-purity glycine. Summary of the invention

[0005] The invention provides a method for preparing high-purity glycine, which solves the problems of low yield and low purity of glycine prepared in the related art.

[0006] The technical solution of the present invention is as follows: The present invention provides a method for preparing high-purity glycine, comprising the following steps: S1, using monoethanolamine and water as reaction raw materials, reacting under the action of a catalyst, filtering to obtain glycine salt, and acidifying and concentrating the glycine salt to obtain crude glycine; S2, recrystallizing the crude glycine to obtain the high-purity glycine; The catalyst is a heavy metal modified molecular sieve.

[0007] As a further technical solution, the mass ratio of monoethanolamine, water and catalyst is 2~6g:12g:15mg.

[0008] As a further technical solution, the reaction temperature is 15-25°C and the reaction time is 1-3h.

[0009] As a further technical solution, the acidification process includes the following steps: adding hydrochloric acid with a mass concentration of 60% to 80% to make the pH value 5.8 to 6.2.

[0010] As a further technical solution, the preparation process of the heavy metal modified molecular sieve includes the following steps: soaking the molecular sieve in a heavy metal nitrate aqueous solution, adding a sodium hydroxide aqueous solution, depositing, and calcining to obtain the heavy metal modified molecular sieve.

[0011] As a further technical solution, in the heavy metal nitrate aqueous solution, the heavy metal nitrate includes one of cadmium nitrate, zirconium nitrate and copper nitrate.

[0012] As a further technical solution, the mass concentration of the heavy metal nitrate aqueous solution is 0.1% to 0.3%, and the mass concentration of the sodium hydroxide aqueous solution is 0.3%.

[0013] As a further technical solution, the molecular sieve includes one of NaX molecular sieve and NaY molecular sieve.

[0014] As a further technical solution, the mass ratio of the heavy metal nitrate aqueous solution, the molecular sieve, and the sodium hydroxide aqueous solution is 1:5 to 15:3.

[0015] As a further technical solution, during the preparation of the heavy metal modified molecular sieve, the immersion temperature is 15-25° C. and the immersion time is 0.5-1.5 h.

[0016] As a further technical solution, during the preparation of the heavy metal modified molecular sieve, the deposition temperature is 15-25° C. and the deposition time is 0.5-1.5 h.

[0017] As a further technical solution, during the preparation of the heavy metal modified molecular sieve, the calcination temperature is 600-700° C. and the calcination time is 1-3 h.

[0018] As a further technical solution, the recrystallization is specifically as follows: dissolving the crude glycine in water to obtain a crude glycine aqueous solution, dropping the crude glycine aqueous solution into the recrystallization solvent, stirring at 15-25°C for 0.5-1.5h after the dropping is complete, filtering, and drying.

[0019] As a further technical solution, the mass ratio of the crude glycine to water is 1:1-3.

[0020] As a further technical solution, the mass ratio of the crude glycine to the recrystallization solvent is 1:3-5.

[0021] As a further technical solution, the recrystallization solvent includes alcohols and ethers, the alcohol includes one of methanol, ethanol, and propanol, and the ether includes one of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether.

[0022] Using a mixed solvent of alcohols and ethers as a recrystallization solvent further improves the yield and purity of the prepared glycine. As a further technical solution, the mass ratio of the alcohol to the ether is 3-5:1.

[0023] As a further technical solution, the mass ratio of the alcohol to the ether is 4:1.

[0024] When the mass ratio of alcohol to ether is 3-5:1, the yield and purity of glycine are further improved, and when the mass ratio of alcohol to ether is 4:1, the yield and purity of glycine are optimal.

[0025] The working principle and beneficial effects of the present invention are: In the present invention, heavy metal modified molecular sieve is used as a catalyst, which can efficiently catalyze the reaction of monoethanolamine and water, reduce unnecessary side reactions, significantly improve the yield and purity of glycine preparation, and meet the growing market demand for high-purity glycine. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the following examples and comparative examples, the model of NaX molecular sieve is 13X, and the manufacturer is Zhengzhou Chaorong Nanomaterial Co., Ltd.; the model of NaY molecular sieve is Y, and the manufacturer is Dalian Zeer Catalytic Materials Co., Ltd.

[0028] Example 1 A method for preparing high-purity glycine comprises the following steps: S1. Using monoethanolamine and water as reaction raw materials, the mass ratio of monoethanolamine, water and heavy metal modified molecular sieve is 6g:12g:15mg, reacting under the action of heavy metal modified molecular sieve at 25°C for 1h, filtering to obtain glycine salt, adjusting the pH of glycine salt to 6.2 with hydrochloric acid with a mass concentration of 80%, concentrating to obtain crude glycine; S2, recrystallizing the crude glycine to obtain high-purity glycine; The preparation process of heavy metal modified molecular sieve includes the following steps: immersing NaY molecular sieve in a cadmium nitrate aqueous solution with a mass concentration of 0.3%, the immersion temperature is 25°C, the immersion time is 0.5h, adding a sodium hydroxide aqueous solution with a mass concentration of 0.3%, depositing at 25°C for 0.5h, and calcining at 700°C for 1h to obtain a heavy metal modified molecular sieve, wherein the mass ratio of the cadmium nitrate aqueous solution, the NaY molecular sieve, and the sodium hydroxide aqueous solution is 1:15:3.

[0029] The recrystallization comprises the following steps: dissolving crude glycine in water of which the mass is three times that of the crude glycine to obtain a crude glycine aqueous solution, dropping the crude glycine aqueous solution into a mixed solvent of methanol and ethylene glycol monomethyl ether, stirring at 25° C. for 0.5 h after the dropping is complete, filtering, and drying, wherein the mass ratio of methanol to ethylene glycol monomethyl ether is 5:1, and the mass ratio of the crude glycine to the mixed solvent is 1:5.

[0030] Example 2 A method for preparing high-purity glycine comprises the following steps: S1. Using monoethanolamine and water as reaction raw materials, the mass ratio of monoethanolamine, water and heavy metal modified molecular sieve is 2g:12g:15mg, reacting under the action of heavy metal modified molecular sieve at 15°C for 3h, filtering to obtain glycine salt, adjusting the pH of glycine salt to 5.8 with hydrochloric acid with a mass concentration of 60%, concentrating to obtain crude glycine; S2, recrystallizing the crude glycine to obtain high-purity glycine; The preparation process of heavy metal modified molecular sieve includes the following steps: soaking NaX molecular sieve in a copper nitrate aqueous solution with a mass concentration of 0.1%, the soaking temperature is 15°C, the soaking time is 1.5 hours, adding a sodium hydroxide aqueous solution with a mass concentration of 0.3%, depositing at 15°C for 1.5 hours, and roasting at 600°C for 3 hours to obtain a heavy metal modified molecular sieve, and the mass ratio of the copper nitrate aqueous solution, the NaX molecular sieve, and the sodium hydroxide aqueous solution is 1:5:3.

[0031] The recrystallization comprises the following steps: dissolving crude glycine in water of the same mass as the crude glycine to obtain a crude glycine aqueous solution, dropping the crude glycine aqueous solution into a mixed solvent of ethanol and ethylene glycol monoethyl ether, stirring at 15°C for 1.5h, filtering, and drying, wherein the mass ratio of ethanol to ethylene glycol monoethyl ether is 3:1, and the mass ratio of the crude glycine to the mixed solvent is 1:3.

[0032] Example 3 A method for preparing high-purity glycine comprises the following steps: S1. Using monoethanolamine and water as reaction raw materials, the mass ratio of monoethanolamine, water and heavy metal modified molecular sieve is 4g:12g:15mg, reacting under the action of heavy metal modified molecular sieve at 20°C for 2h, filtering to obtain glycine salt, adjusting the pH of glycine salt to 6.0 with hydrochloric acid with a mass concentration of 70%, concentrating to obtain crude glycine; S2, recrystallizing the crude glycine to obtain high-purity glycine; The preparation process of heavy metal modified molecular sieve includes the following steps: soaking NaX molecular sieve in a zirconium nitrate aqueous solution with a mass concentration of 0.2%, the soaking temperature is 20°C, the soaking time is 2h, adding a sodium hydroxide aqueous solution with a mass concentration of 0.3%, depositing at 20°C for 1h, and calcining at 650°C for 1h to obtain a heavy metal modified molecular sieve, and the mass ratio of the zirconium nitrate aqueous solution, the NaX molecular sieve, and the sodium hydroxide aqueous solution is 1:10:3.

[0033] The recrystallization comprises the following steps: dissolving crude glycine in water with a mass twice that of the crude glycine to obtain a crude glycine aqueous solution, dropping the crude glycine aqueous solution into a mixed solvent of propanol and ethylene glycol monobutyl ether, stirring at 20° C. for 1 hour after the dropping is completed, filtering, and drying, wherein the mass ratio of propanol to ethylene glycol monobutyl ether is 2:1, and the mass ratio of the crude glycine to the mixed solvent is 1:4.

[0034] Example 4 The only difference between this embodiment and embodiment 3 is that the solvent for recrystallization in this embodiment is diethanol monobutyl ether, and the mass ratio of crude glycine to diethanol monobutyl ether is 1:4.

[0035] Example 5 The only difference between this embodiment and embodiment 3 is that the solvent for recrystallization in this embodiment is propanol, and the mass ratio of crude glycine to propanol is 1:4.

[0036] Example 6 The only difference between this embodiment and embodiment 3 is that the mass ratio of propanol to ethylene glycol monobutyl ether in this embodiment is 6:1.

[0037] Example 7 The only difference between this embodiment and embodiment 3 is that the mass ratio of propanol to ethylene glycol monobutyl ether in this embodiment is 3:1.

[0038] Example 8 The only difference between this embodiment and embodiment 3 is that the mass ratio of propanol to ethylene glycol monobutyl ether in this embodiment is 4:1.

[0039] Example 9 The only difference between this embodiment and embodiment 3 is that the mass ratio of propanol to ethylene glycol monobutyl ether in this embodiment is 5:1.

[0040] Comparative Example 1 A method for preparing high-purity glycine comprises the following steps: S1. Using monoethanolamine and water as reaction raw materials, the mass ratio of monoethanolamine, water and NaX molecular sieve is 2g:12g:15mg, reacting under the action of NaX molecular sieve at 15°C for 3h, filtering to obtain glycine salt, adjusting the pH of glycine salt to 5.8 with hydrochloric acid with a mass concentration of 60%, concentrating to obtain crude glycine; S2, recrystallizing the crude glycine to obtain high-purity glycine; The recrystallization comprises the following steps: dissolving crude glycine in water of the same mass as the crude glycine to obtain a crude glycine aqueous solution, dropping the crude glycine aqueous solution into a mixed solvent of ethanol and ethylene glycol monoethyl ether, stirring at 15° C. for 1.5 hours after the dropping is completed, filtering, and drying, wherein the mass ratio of ethanol to ethylene glycol monoethyl ether is 3:1, and the mass ratio of the crude glycine to the mixed solvent is 1:3.

[0041] Comparative Example 2 A method for preparing high-purity glycine comprises the following steps: S1. Using monoethanolamine and water as reaction raw materials, the mass ratio of monoethanolamine, water and copper oxide is 2g:12g:15mg, reacting under the action of copper oxide at 15°C for 3h, filtering to obtain glycine salt, adjusting the pH of the glycine salt to 5.8 with hydrochloric acid with a mass concentration of 60%, concentrating to obtain crude glycine; S2, recrystallizing the crude glycine to obtain high-purity glycine; The recrystallization comprises the following steps: dissolving crude glycine in water of the same mass as the crude glycine to obtain a crude glycine aqueous solution, dropping the crude glycine aqueous solution into a mixed solvent of ethanol and ethylene glycol monoethyl ether, stirring at 15° C. for 1.5 hours after the dropping is completed, filtering, and drying, wherein the mass ratio of ethanol to ethylene glycol monoethyl ether is 3:1, and the mass ratio of the crude glycine to the mixed solvent is 1:3.

[0042] Comparative Example 3 A method for preparing high-purity glycine comprises the following steps: S1. Using monoethanolamine and water as reaction raw materials, the mass ratio of monoethanolamine to water is 2g:12g, reacting at 15°C for 3h, filtering to obtain glycine salt, adjusting the pH of the glycine salt to 5.8 with 60% hydrochloric acid, concentrating to obtain crude glycine; S2, recrystallizing the crude glycine to obtain high-purity glycine; The recrystallization comprises the following steps: dissolving crude glycine in water of the same mass as the crude glycine to obtain a crude glycine aqueous solution, dropping the crude glycine aqueous solution into a mixed solvent of ethanol and ethylene glycol monoethyl ether, cooling the temperature to 15°C at a rate of -20°C / h after the dropping is completed, and stirring at the temperature for 1.5h, filtering, and drying. The mass ratio of ethanol to ethylene glycol monoethyl ether is 3:1, and the mass ratio of the crude glycine to the mixed solvent is 1:3.

[0043] Test example The yield and purity of the high-purity glycine obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were tested. The purity of glycine was tested by high performance liquid chromatography, and the chromatographic conditions were as follows: chromatographic column: aminopropyl bonded silica gel chromatographic column, 250mm×4.6mm, 5μm; mobile phase: a mixed solution of acetonitrile and phosphate buffer in a volume ratio of 72:28, wherein the concentration of phosphate buffer was 15mmol / L, 0.2wt% triethylamine was added, and the pH was adjusted to 6.2 with phosphoric acid; flow rate: 1.0mL / min; column temperature: 25°C; injection volume: 20μl; detection wavelength: UV210nm. The glycine yield was calculated as follows: A=[(m2×B) / M2] / (m1 / M1) m2 is the mass of the obtained high-purity glycine, B is the purity of glycine measured by high performance liquid chromatography, M2 is the molar mass of glycine, m1 is the mass of monoethanolamine, and M1 is the molar mass of monoethanolamine.

[0044] The yield and purity test results of high-purity glycine obtained in Examples 1 to 9 and Comparative Examples 1 to 3 are shown in Table 1.

[0045]

[0046] By comparing Example 2 with Comparative Examples 1 to 3, it can be seen that the yield and purity of glycine can be improved by using heavy metal modified molecular sieve for catalysis.

[0047] By comparing Examples 3, 6 to 9 with Examples 4 to 5, it can be seen that the use of alcohols and ethers as recrystallization solvents can further improve the yield and purity of glycine. By comparing Examples 3, 6 and 7 to 9, it can be seen that when the mass ratio of alcohol to ether is 3 to 5:1, the yield and purity of glycine can be further improved, and when the mass ratio of alcohol to ether is 4:1, the yield and purity of glycine are optimal.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing high-purity glycine, characterized in that: The following steps are involved: S1, using monoethanolamine and water as reaction raw materials, reacting under the action of a catalyst, filtering to obtain glycine salt, and acidifying and concentrating the glycine salt to obtain crude glycine; S2, recrystallizing the crude glycine to obtain the high-purity glycine; The catalyst is a heavy metal modified molecular sieve.

2. The method for preparing high-purity glycine according to claim 1, characterized in that: The mass ratio of the monoethanolamine, water and catalyst is 2-6 g:12 g:15 mg.

3. The method for preparing high-purity glycine according to claim 1, characterized in that: The preparation process of the heavy metal modified molecular sieve comprises the following steps: soaking the molecular sieve in a heavy metal nitrate aqueous solution, adding a sodium hydroxide aqueous solution, depositing, and calcining to obtain the heavy metal modified molecular sieve.

4. The method for preparing high-purity glycine according to claim 3, characterized in that: In the heavy metal nitrate aqueous solution, the heavy metal nitrate includes one of cadmium nitrate, zirconium nitrate and copper nitrate.

5. The method for preparing high-purity glycine according to claim 3, characterized in that: The mass concentration of the heavy metal nitrate aqueous solution is 0.1% to 0.3%, and the mass concentration of the sodium hydroxide aqueous solution is 0.3%.

6. The method for preparing high-purity glycine according to claim 3, characterized in that: The molecular sieve includes one of NaX molecular sieve and NaY molecular sieve.

7. The method for preparing high-purity glycine according to claim 3, characterized in that: The mass ratio of the heavy metal nitrate aqueous solution, the molecular sieve and the sodium hydroxide aqueous solution is 1:5-15:

3.

8. The method for preparing high-purity glycine according to claim 1, characterized in that: The recrystallization is specifically as follows: dissolving the crude glycine in water to obtain a crude glycine aqueous solution, dropping the crude glycine aqueous solution into a recrystallization solvent, stirring at 15-25° C. for 0.5-1.5 h after the dropping is complete, filtering, and drying.

9. The method for preparing high-purity glycine according to claim 8, characterized in that: The recrystallization solvent includes alcohols and ethers, the alcohol includes one of methanol, ethanol, and propanol, and the ether includes one of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether.

10. The method for preparing high-purity glycine according to claim 9, characterized in that: The mass ratio of the alcohol to the ether is 3-5:1.

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