Preparation method of sodium sarcosinate
By reacting chloroacetic acid with aqueous solution of sodium carbonate with methylamine and recycling methylamine, the existing sodium sarcosine preparation process equipment has solved the problem of high requirements and low yield, and high purity and low cost preparation is achieved. The entire process is free of solid waste and wastewater, and it has green and environmentally friendly characteristics.
Patent Information
- Application Number
- CN202411788691.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-03
- Publication Date
- 2025-04-11
AI Technical Summary
The existing sodium sarcosine preparation process has problems such as high equipment requirements, low yield, and the need for highly toxic raw materials, and lacks a green and environmentally friendly optimized synthesis process.
The preparation method of mixing the aqueous chloroacetic acid solution with the aqueous sodium carbonate solution, then reacting with the aqueous methylamine solution, and then adding a lye solution to recover the methylamine, and finally obtaining high-purity sodium sarcosine by concentration.
It has achieved high purity and low cost sodium sarcosine preparation, good fluidity, easy transportation and storage, and there is no solid waste or wastewater production in the entire process, and it has green and environmentally friendly characteristics.
Abstract
Description
Technical Field
[0001] The present application relates to the field of chemical technology, and in particular to a method for preparing sodium sarcosinate. Background Art
[0002] The structural formula of sodium sarcosinate is CH3NHCHCOONa, also known as sodium N-methylglycinate. It is a white triangular crystal, very soluble in water, slightly soluble in ethanol, and alkaline in water, with a solution pH of about 12-13. When sodium sarcosinate is heated to 210℃-220℃, most of it loses a molecule of water and decomposes, and a small part decomposes into dimethylamine and carbon dioxide. Aqueous solutions with a sodium sarcosinate content of more than 40% are easy to polymerize, with a relative density of 1.198 and a boiling point of 108℃.
[0003] The production processes of sodium sarcosinate mainly include the chloroacetic acid method and the hydroxyacetonitrile method. The chloroacetic acid method is to react sodium chloroacetate and methylamine aqueous solution in the presence of sodium hydroxide at 80°C-85°C and 0.15-0.2MPa pressure for several hours to obtain the product. The chloroacetic acid method needs to be carried out under pressure, and the reaction conditions are relatively high. It has high requirements for equipment used in large-scale industrial production, and the yield is not high. The hydroxyacetonitrile method is mainly a condensation reaction of hydroxyacetonitrile (or hydrocyanic acid and formaldehyde directly involved in the reaction) with monomethylamine, and then alkaline hydrolysis with liquid alkali to produce sodium sarcosinate. However, hydrocyanic acid is highly toxic and the raw materials are difficult to obtain.
[0004] Sodium sarcosinate and its downstream products have a very wide range of uses, and its downstream products are all naturally degradable products, which are environmentally friendly. Its series of products have good application prospects, so it is very important to optimize the green synthesis process. Summary of the invention
[0005] In order to solve the above technical problems existing in the prior art, the present application provides a method for preparing sodium sarcosinate, wherein the sodium sarcosinate prepared by the method has high purity, low cost, good fluidity, and is convenient for transportation, storage and use. In addition, the preparation method provided by the present application generates substantially no solid waste and wastewater during the entire process, is waste-free, and is green and environmentally friendly.
[0006] The preparation method of sodium sarcosinate provided in the present application comprises the following steps:
[0007] S1: mixing a chloroacetic acid aqueous solution and a sodium carbonate aqueous solution to obtain a first mixed solution;
[0008] S2: adding the first mixed solution of step S1 into the methylamine aqueous solution to react, thereby obtaining a second mixed solution containing sodium sarcosinate, methylamine hydrochloride and methylamine;
[0009] S3: adding alkaline solution to the second mixed solution in step S2 to recover methylamine, thereby obtaining tail gas containing methylamine and a third mixed solution after methylamine is removed;
[0010] S4: Concentrating the third mixed solution of step S3 to obtain a material containing sodium sarcosinate.
[0011] In some embodiments, the concentration of the sodium carbonate aqueous solution is 15%-30%, for example, 16%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or any value therebetween. In some embodiments, the concentration of the sodium carbonate aqueous solution is 20%-25%. When the concentration of the sodium carbonate aqueous solution is too high, pH adjustment is difficult to control and is easily out of range. When the concentration of the sodium carbonate aqueous solution is too low, its dosage increases, which reduces the concentration of chloroacetic acid in the system and affects the yield of the final product sodium sarcosinate.
[0012] In some embodiments, the concentration of the chloroacetic acid aqueous solution is 40%-80%, for example, 41%, 43%, 45%, 47%, 49%, 50%, 51%, 53%, 55%, 57%, 59%, 60%, 61%, 63%, 65%, 67%, 69%, 70%, 71%, 73%, 75%, 77%, 79% or any value therebetween. In some embodiments, the concentration of the chloroacetic acid aqueous solution is 50%-60%.
[0013] In some embodiments, in step S1, the pH of the first mixed solution is 6-8, for example, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 or any value therebetween. In some embodiments, the pH of the first mixed solution is 6.5-7.5. When the pH is too high, the amount of sodium carbonate is increased to reduce the concentration of chloroacetic acid in the system. When the pH is too low, it is not conducive to the forward reaction of chloroacetic acid and monomethylamine, affecting the yield of the final product sodium sarcosinate.
[0014] In some embodiments, in step S1, the mixing temperature is 5°C-35°C, for example, 7°C, 9°C, 10°C, 11°C, 13°C, 15°C, 17°C, 19°C, 20°C, 21°C, 23°C, 25°C, 27°C, 29°C, 30°C, 31°C, 33°C or any value therebetween. In some embodiments, in step S1, the mixing temperature is 15°C-25°C. When the temperature is too high, the amount of sodium carbonate aqueous solution increases, reducing the concentration of chloroacetic acid in the system. When the temperature is too low, the reaction is slow and energy consumption increases.
[0015] In some embodiments, in step S2, the reaction temperature is 5°C-35°C, such as 7°C, 9°C, 10°C, 11°C, 13°C, 15°C, 17°C, 19°C, 20°C, 21°C, 23°C, 25°C, 27°C, 29°C, 30°C, 31°C, 33°C or any value therebetween. In step S2, the reaction temperature is 15°C-25°C.
[0016] In some embodiments, the concentration of the methylamine aqueous solution is 30%-50%, for example, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or any value therebetween. In some embodiments, the concentration of the methylamine aqueous solution is 35%-45%.
[0017] In some embodiments, the molar ratio of the aqueous chloroacetic acid solution to the aqueous methylamine solution is 1:(5-9), such as 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5 or any value therebetween, based on methylamine and chloroacetic acid. In some embodiments, the molar ratio of the aqueous chloroacetic acid solution to the aqueous methylamine solution is 1:(6-8).
[0018] In some embodiments, the amount of the methylamine aqueous solution is n(chloroacetic acid):n(methylamine)=1:5-9, preferably 1:6-8.
[0019] In some embodiments, the first mixed solution is added at a uniform rate. In some embodiments, the first mixed solution is added in 2-5 hours, such as 2.5 hours, 3 hours, 3.5 hours, 4 hours or 4.5 hours. In some embodiments, the first mixed solution is added in 3-4 hours.
[0020] In some embodiments, in step S3, the alkali solution is selected from sodium hydroxide solution.
[0021] In some embodiments, the concentration of the sodium hydroxide solution is 30%-50%, for example, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or any value therebetween.
[0022] In some embodiments, the molar ratio of the aqueous chloroacetic acid solution to the aqueous sodium hydroxide solution is 1:(1.2-2), such as 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45, 1:1.5, 1:1.55, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or any value therebetween. In some embodiments, the molar ratio of the aqueous chloroacetic acid solution to the aqueous sodium hydroxide solution is 1:(1.3-1.5).
[0023] In some embodiments, the amount of the sodium hydroxide aqueous solution is n(chloroacetic acid):n(sodium hydroxide)=1.0:1.2-1.6, preferably 1.0:1.3-1.5.
[0024] In some embodiments, in step S3, an alkaline solution is added to the second mixed solution at a uniform rate to recover methylamine.
[0025] In some embodiments, the addition of alkali solution is completed in 0.5-2 h, such as 0.7 h, 0.9 h, 1.1 h, 1.3 h, 1.5 h, 1.7 h or 1.9 h. In some embodiments, the addition of alkali solution is completed in 1-1.5 h.
[0026] In some embodiments, the methylamine recovery includes a first stage methylamine recovery during the process of adding the alkali solution to the second mixed liquor and a second stage methylamine recovery after the addition of the alkali solution is completed.
[0027] In some embodiments, the temperature of the first stage methylamine recovery is 40°C-60°C, for example, 45°C, 50°C or 55°C.
[0028] In some embodiments, the temperature of the second stage methylamine recovery is 60°C-95°C, for example, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C.
[0029] In some embodiments, in step S3, the tail gas containing methylamine is introduced into a methylamine recovery system, preferably a methylamine recovery condensation device, to obtain a recovered methylamine aqueous solution.
[0030] In some embodiments, after the methylamine content in the recovered methylamine aqueous solution reaches 35%-40%, the recovered methylamine aqueous solution is recycled to step S2.
[0031] In some embodiments, in step S4, when the sodium sarcosinate content in the sodium sarcosinate-containing material is 35%-40%, concentration is stopped.
[0032] In some embodiments, in step S4, the concentration is performed under negative pressure conditions.
[0033] In some embodiments, the preparation method further comprises passing the distilled water concentrated in step S4 into a methylamine recovery system to recover methylamine.
[0034] In some embodiments, the method for preparing sodium sarcosinate comprises the following specific steps:
[0035] (1) Mix an aqueous solution of chloroacetic acid and an aqueous solution of sodium carbonate.
[0036] (2) The material described in step (1) is added to a monomethylamine aqueous solution at a uniform rate to react, thereby obtaining a mixed aqueous solution of sodium sarcosinate, monomethylamine hydrochloride and monomethylamine.
[0037] (3) adding liquid caustic soda to the mixed aqueous solution described in step (2) at a uniform rate, controlling the temperature to rise naturally during the addition process, driving out the methylamine tail gas and connecting a methylamine recovery condensation device, and continuing to raise the temperature to drive out the methylamine after the addition of liquid caustic soda is completed. When the free amine content in the aqueous solution is tested to be qualified, the methylamine driving is stopped. When the methylamine aqueous solution content in the methylamine recovery system reaches 35-40%, the reaction can be carried out.
[0038] (4) Weigh the material in step (3) and concentrate the water until the content of sodium sarcosinate is 35-38%, then stop the concentration and discharge the material to obtain sodium sarcosinate. The concentrated distilled water contains a small amount of amine and can enter the methylamine recovery system to continue to absorb methylamine.
[0039] The beneficial effects of this application are:
[0040] (1) The sodium sarcosinate prepared in the present application has high purity, low cost and good fluidity, and is easy to transport, store and use.
[0041] (2) The entire process of this application generates almost no solid waste or wastewater, so this method does not generate "three wastes", is wasteless, is green and environmentally friendly, and is a clean and green process. DETAILED DESCRIPTION
[0042] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. The specific embodiments described here are only used to explain the present application and are not intended to constitute any limitation to the present application.
[0043] Unless otherwise specified, % in the following examples and comparative examples represents mass percentage.
[0044] Example 1
[0045] Take flask No. 1, add 94.5g chloroacetic acid (pure) and 94.5g water, stir and dissolve to obtain 50% chloroacetic acid aqueous solution (or use 80% chloroacetic acid and add a small amount of water). Then add 20% sodium carbonate aqueous solution to the chloroacetic acid aqueous solution, control the temperature to 25°C, add until the pH is 7.3, and obtain a mixed solution.
[0046] Take flask No. 2, add 504.7g of 40% monomethylamine, control the temperature at 20±5°C, and start to add the above mixed solution, control the temperature at 20±5°C during the addition process, and control the addition to end after about 3-4 hours. After the addition is completed, continue to control the temperature at 20-25°C to react for 1-2 hours to obtain a mixed aqueous solution containing sodium sarcosinate, monomethylamine hydrochloride and monomethylamine. After the reaction is completed, transfer the mixed aqueous solution to flask No. 3.
[0047] The temperature was raised to 40°C and 116.7 g of 48% liquid caustic soda was added. The temperature was gradually raised to 60°C during the addition of liquid caustic soda, and methylamine was recovered by tail negative pressure synchronously. After the addition of liquid caustic soda was completed, the temperature was slowly raised by 10°C every half an hour, and the recovery of methylamine was stopped after the temperature reached 95°C. The free amine was sampled and tested to be less than 1% and the recovery was stopped (the methylamine recovery time can be slightly extended if the methylamine absorption effect is poor. The methylamine recovery device is a three-stage absorption bottle, which is put into cold water and placed in an ice water bath).
[0048] After the methylamine recovery is completed, the condensed water is transferred to the concentration bottle and negative pressure concentration is started to be discharged. The concentrated condensed water is pumped into the methylamine condensation recovery tower to circulate and recover methylamine, and 272.3g of sodium sarcosine feed liquid is obtained, with a yield of 88.99%.
[0049] Example 2
[0050] The only difference from Example 1 is that the concentration of the sodium carbonate aqueous solution is 10%. 220.3 g of sodium sarcosinate-containing feed solution is obtained, with a yield of 72.00%.
[0051] Example 3
[0052] The only difference from Example 1 is that the concentration of the sodium carbonate aqueous solution is 35%. 226.9 g of sodium sarcosinate-containing feed solution is obtained, with a yield of 74.15%.
[0053] Example 4
[0054] The only difference from Example 1 is that the sodium carbonate aqueous solution is added dropwise until the pH reaches 5.5, and the addition is terminated. 205.7 g of sodium sarcosinate-containing feed solution is obtained, with a yield of 67.24%.
[0055] Example 5
[0056] The only difference from Example 1 is that the sodium carbonate aqueous solution is added dropwise until the pH reaches 8.5, and the addition is terminated. 200.1 g of sodium sarcosinate-containing feed solution is obtained, with a yield of 65.39%.
[0057] Example 6
[0058] The only difference from Example 1 is that the sodium carbonate aqueous solution is added dropwise at a controlled temperature of 5° C. 186.2 g of sodium sarcosinate-containing feed solution is obtained with a yield of 60.85%.
[0059] Example 7
[0060] The only difference from Example 1 is that the sodium carbonate aqueous solution is added dropwise at a controlled temperature of 35° C. 230.4 g of sodium sarcosinate-containing feed solution is obtained, with a yield of 75.3%.
[0061] Example 8
[0062] The only difference from Example 1 is that the temperature of the first mixed solution is controlled at 15° C. 235.0 g of sodium sarcosinate-containing feed solution is obtained, with a yield of 76.79%.
[0063] Example 9
[0064] The only difference from Example 1 is that the temperature of the first mixed solution is controlled at 35° C. during the addition process. 257.5 g of sodium sarcosinate-containing feed solution is obtained with a yield of 84.15%.
[0065] Example 10
[0066] The only difference from Example 1 is that the amount of methylamine aqueous solution used is 310.57 g, that is, n (chloroacetic acid): n (methylamine) = 1: 4. 208.9 g of sodium sarcosinate solution is obtained, with a yield of 68.26%.
[0067] Embodiment 11
[0068] The only difference from Example 1 is that the acceleration of the first mixed liquid flow is 2 h. 242.5 g of sodium sarcosinate-containing feed liquid is obtained, with a yield of 79.24%.
[0069] Example 12
[0070] The only difference from Example 1 is that the amount of liquid caustic soda used is 91.7 g, that is, n (chloroacetic acid): n (sodium hydroxide) = 1.0: 1.1. 230.6 g of sodium sarcosinate-containing liquid is obtained, with a yield of 75.36%.
[0071] Example 13
[0072] Add 945.0 kg of chloroacetic acid (pure) and 945.0 kg of water into a mixing kettle, stir and dissolve to obtain a 50% chloroacetic acid aqueous solution (or 80% chloroacetic acid plus a small amount of water). Then add a 20% sodium carbonate aqueous solution to the chloroacetic acid aqueous solution, control the temperature to 25°C, and add until the pH is 7.3 to obtain a mixed solution.
[0073] Add 5047.0 kg of 40% monomethylamine to the synthesis furnace, control the temperature at 20±5°C, and start to add the above mixed solution. The temperature of the addition process is controlled at 20±5°C, and the addition is completed after about 3-4 hours. After the addition is completed, continue to control the temperature at 20-25°C to react for 1-2 hours to obtain a mixed aqueous solution containing sodium sarcosinate, monomethylamine hydrochloride and monomethylamine. After the reaction is completed, the mixed aqueous solution is transferred to the deamination kettle.
[0074] After transferring to the demethylamine kettle, the temperature is raised to 40°C and 1167.0 kg of 48% liquid caustic soda is added. The temperature is gradually raised to 60°C during the addition of liquid caustic soda, and methylamine is recovered synchronously under tail negative pressure. After the addition of liquid caustic soda is completed, the temperature is slowly raised, increasing by 10°C every half an hour, and the recovery of methylamine is stopped after reaching 95°C. The process is terminated after the free amine is controlled and detected to be less than 1% (the methylamine recovery time can be slightly extended if the methylamine absorption effect is poor. The methylamine recovery device is a three-stage falling film absorption, and the falling film absorption needs to be cooled with ice water).
[0075] After the recovery of methylamine is completed, negative pressure concentration of water is started, and the concentration is stopped until the sodium sarcosinate content reaches 35.18%. The concentrated condensed water is pumped into the methylamine condensation recovery tower to circulate and recover methylamine, and 2758.9 kg of sodium sarcosinate liquid is obtained, with a yield of 87.38%.
[0076] The technical solution of the present application is not limited to the above-mentioned specific embodiments, and all technical variations made according to the technical solution of the present application fall within the protection scope of the present application.
Claims
1. A method for preparing sodium sarcosinate, comprising the following steps: S1: mixing a chloroacetic acid aqueous solution and a sodium carbonate aqueous solution to obtain a first mixed solution; S2: adding the first mixed solution of step S1 into the methylamine aqueous solution to react, thereby obtaining a second mixed solution containing sodium sarcosinate, methylamine hydrochloride and methylamine; S3: adding alkaline solution to the second mixed solution in step S2 to recover methylamine, thereby obtaining tail gas containing methylamine and a third mixed solution after methylamine is removed; S4: Concentrating the third mixed solution of step S3 to obtain a material containing sodium sarcosinate.
2. The preparation method according to claim 1, characterized in that: In step S1, the concentration of the sodium carbonate aqueous solution is 15%-30%, preferably 20%-25%; The concentration of the chloroacetic acid aqueous solution is 40%-80%, preferably 50%-60%.
3. The preparation method according to claim 1 or 2, characterized in that: In step S1, the pH of the first mixed solution is 6-8, preferably 6.5-7.
5.
4. The preparation method according to any one of claims 1 to 3, characterized in that In step S1, the mixing temperature is 5°C-35°C, preferably 15°C-25°C.
5. The preparation method according to any one of claims 1 to 4, characterized in that: In step S2, the reaction temperature is 15°C-35°C, preferably 25°C-30°C; and / or The concentration of the methylamine aqueous solution is 30%-50%, preferably 35%-45%; and / or The molar ratio of the aqueous chloroacetic acid solution to the aqueous methylamine solution is 1:(5-9), preferably 1:(6-8), based on methylamine and chloroacetic acid; and / or The first mixed solution is added at a uniform rate, preferably for 2-5 hours, more preferably for 3-4 hours.
6. The preparation method according to any one of claims 1 to 5, characterized in that: In step S3, the alkali solution is selected from a sodium hydroxide aqueous solution, and preferably the concentration of the sodium hydroxide aqueous solution is 30%-50%; and / or The molar ratio of the aqueous solution of chloroacetic acid to the aqueous solution of sodium hydroxide is 1:(1.2-2), preferably 1:(1.3-1.5), based on sodium hydroxide and chloroacetic acid; and / or The alkali solution is added at a uniform rate, preferably for 0.5-2 hours, more preferably for 1-1.5 hours; and / or The methylamine recovery includes a first-stage methylamine recovery during the process of adding the alkali solution to the second mixed liquor and a second-stage methylamine recovery after the alkali solution addition is completed.
7. The preparation method according to claim 6, characterized in that: The temperature of methylamine recovery in the first stage is 40°C-60°C; the temperature of methylamine recovery in the second stage is 60°C-95°C.
8. The preparation method according to any one of claims 1 to 7, characterized in that: In step S3, the tail gas containing methylamine is passed into a methylamine recovery system, preferably a methylamine recovery condensation device, to obtain a recovered methylamine aqueous solution; Preferably, after the methylamine content in the recovered methylamine aqueous solution reaches 35%-40%, the recovered methylamine aqueous solution is recycled to step S2.
9. The preparation method according to any one of claims 1 to 8, characterized in that: In step S4, when the sodium sarcosinate content in the sodium sarcosinate-containing material is 35%-40%, the concentration is stopped; and / or the concentration is performed under negative pressure conditions.
10. The preparation method according to claim 9, characterized in that: The preparation method further comprises passing the distilled water concentrated in step S4 into a methylamine recovery system to recover methylamine.