CN111196766A - Purification and desalination method of L-carnitine crude product - Google Patents
Purification and desalination method of L-carnitine crude product Download PDFInfo
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- CN111196766A CN111196766A CN201811370159.7A CN201811370159A CN111196766A CN 111196766 A CN111196766 A CN 111196766A CN 201811370159 A CN201811370159 A CN 201811370159A CN 111196766 A CN111196766 A CN 111196766A
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Abstract
The invention discloses a purification and desalination method of a crude L-carnitine product, which comprises the following steps: dissolving the crude L-carnitine product in a lower alkyl alcohol mixed solvent added with fatty acid fatty ester, wherein the volume-weight ratio of the mixed solvent to the weight of the crude L-carnitine product is greater than 1, stirring and mixing uniformly, filtering, removing precipitates insoluble in the organic solvent to obtain an L-carnitine solution, and removing the organic solvent by vacuum concentration to obtain the pure L-carnitine product. The purification and desalination method of the invention realizes the purification and desalination by utilizing the characteristics that halide inorganic salt is completely insoluble in lower alkyl alcohol added with fatty acid fatty ester, and L-carnitine can be dissolved in the mixed solvent, and the like, and can obtain the L-carnitine product with high purity.
Description
Technical Field
The invention relates to a production technology of L-carnitine, in particular to a purification and desalination method of a crude product of L-carnitine.
Background
L-carnitine, or L-carnitine, known as L-carnitine or vitamin BT, which is known by the chemical name β -hydroxygamma-trimethylaminebutyric acid, is a white crystalline lens or a white transparent fine powder.
Currently, the main synthetic methods of L-carnitine are: resolution of racemate, biosynthesis and chemical synthesis. The chemical synthesis routes mainly comprise two routes, one is that (R) - (-) -4-halo-3-hydroxybutyrate and trimethylamine are subjected to amination reaction under alkaline condition to generate L-carnitine; the other method is that L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide is hydrolyzed by strong alkali to generate L-carnitine, and the two chemical synthesis methods have the advantages of simple synthetic process route, high unit yield, cheap and easily available raw materials and the like.
The synthesis of L-carnitine by chemical synthesis has been reported in many documents, such as EP-B-295109, EP-A-339764, JP01211551 and US 6566552. The purification and desalination method of L-carnitine obtained by chemical synthesis method is mainly ion exchange method, for example, WO2007139238 and CN1727328A are used to concentrate the synthesized product, then the concentrated product is dissolved by water and treated by anion exchange resin to remove the salt produced in the reaction, such as sodium chloride and other impurities, and finally the mixed solvent of absolute ethyl alcohol and acetone (1 + 7) is used for recrystallization. The process uses 10% ammonia water to wash the exchange resin to obtain the product, and then uses hydrochloric acid solution to regenerate the column, thereby consuming a large amount of ammonia water and hydrochloric acid and generating a large amount of waste water, and consuming a large amount of organic solvent. The CN101735068A method for desalting and purifying in the production of L-carnitine is a nanofiltration membrane method, which needs to adjust the salt concentration in the solution, the pH value of the solution, and needs to purchase equipment such as a liquid storage tank, pump circulation and the like, and has the characteristics of large investment, multiple operation steps and the like. CN101274899A adopts electrodialysis method to remove salt such as sodium chloride and ammonium chloride generated in production, and this technique needs to install one or more electrodialysis devices to purchase osmosis membrane, and has the characteristics of large electric energy consumption, large investment, high operation cost, etc.
Disclosure of Invention
The invention aims to provide a purification and desalination method of a crude L-carnitine product, which utilizes the characteristics that halide inorganic salt is completely insoluble in lower alkyl alcohol added with fatty acid fatty ester, and L-carnitine can be dissolved in a mixed solvent, and the like to realize purification and desalination and obtain a high-purity L-carnitine product.
The technical scheme of the invention is as follows:
the purification and desalination method of the L-carnitine crude product comprises the following steps:
dissolving the crude L-carnitine product in a lower alkyl alcohol mixed solvent added with fatty acid fatty ester, wherein the volume-weight ratio of the mixed solvent to the weight of the crude L-carnitine product is greater than 1, stirring and mixing uniformly, filtering, removing precipitates insoluble in the organic solvent to obtain an L-carnitine solution, and removing the organic solvent by vacuum concentration to obtain the pure L-carnitine product.
The lower alkyl alcohol is C1-C4 lower alkyl alcohol.
The lower alkyl alcohol is one or more of methanol, ethanol, propanol, isopropanol, butanol or isobutanol.
The fatty acid fatty ester is one or more of methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl butyl ester, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate and butyl butyrate.
The volume percentage concentration of the fatty acid fatty ester in the lower alkyl alcohol is 0.1-10%.
The stirring temperature is-30 ℃ to 10 ℃, and the stirring time is 1 to 10 hours.
Washing the precipitate with lower alkyl alcohol of 0-10 deg.c for 3-5 times, merging the filtrate into L-carnitine solution, vacuum concentrating to eliminate organic solvent and obtain pure L-carnitine product.
The preparation method of the L-carnitine crude product comprises the following steps:
A. reacting the intermediate (R) - (-) -4-halo-3-hydroxybutyrate with trimethylamine under the alkaline catalysis to obtain an L-carnitine reaction solution; or the L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide is used as a raw material and is subjected to hydrogen peroxide water in an alkaline aqueous solution
Obtaining L-carnitine reaction liquid through decomposition;
B. adjusting the L-carnitine reaction solution to be neutral by using inorganic acid, and removing unreacted trimethylamine, water and halogenated alkane by reduced pressure distillation to obtain a thick solid crude product;
C. and (3) cleaning the thick solid crude product by using fatty acid fatty ester to remove residual unreacted organic impurities, and drying to remove water to obtain the L-carnitine crude product.
The fatty acid fatty ester is one or more of methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl butyl ester, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate and butyl butyrate.
The inorganic acid in the step B is hydrochloric acid and/or nitric acid.
The invention has the beneficial effects that:
the impurities contained in the crude product obtained by the chemical synthesis method are mainly trimethylamine inorganic acid salt, water and halide, the crude product of L-carnitine is dissolved in the lower alkyl alcohol mixed solvent added with fatty acid fatty ester by utilizing the characteristics that the halide inorganic acid salt is completely insoluble in the lower alkyl alcohol added with fatty acid fatty ester, and the L-carnitine can be dissolved in the mixed solvent, and the like, so as to remove the halide inorganic acid salt, and finally, the fatty acid fatty ester and the lower alkyl alcohol are removed by vacuum reduced pressure concentration, thereby realizing the purification and desalination of the crude product of L-carnitine. The method does not need to use ion exchange resin, greatly reduces the using amount of the solvent, is more economical and environment-friendly, has high purification speed and good effect, is obviously superior to the prior art, and has outstanding substantive characteristics and remarkable progress.
In the preferred preparation method of the crude L-carnitine, unreacted trimethylamine, water and halogenated alkane can be removed by reduced pressure distillation; the convenience of operation has further been promoted, and is high-efficient swift, and the energy consumption is low.
The method has the advantages of easily obtained raw materials, scientific and reasonable process and simple operation, the purity of the obtained L-carnitine product is up to more than 97 percent, the solvent can be recycled, the recovery rate of the solvent is up to more than 97 percent, the method has little pollution to the environment and is beneficial to large-scale production.
Detailed Description
The present invention will be described in detail with reference to specific examples, but the present invention is not limited thereto.
Example 1
Taking 100g of L-carnitine crude product into 100mL of methanol added with 0.1% methyl formate, stirring for 1 hour at-30 ℃ to uniformly mix the L-carnitine crude product and the methanol, filtering the mixture to remove precipitates insoluble in the organic solvent, washing the precipitates for 3 times by using the methanol stored at the temperature of 0 ℃, merging filtrate into the L-carnitine solution, and concentrating the solution under reduced pressure in vacuum to remove the organic solvent to obtain the pure L-carnitine.
The detection proves that the chemical purity of the L-carnitine product is 97%.
Example 2
The purification process of the crude L-carnitine is the same as in example 1.
The preparation method of the L-carnitine crude product comprises the following steps:
A. carrying out amination reaction on the intermediate (R) - (-) -4-halo-3-hydroxybutyrate and trimethylamine under the catalysis of inorganic base, and reacting in two phases formed by organic-phase halogenated alkane and water to obtain L-carnitine reaction liquid;
B. adjusting the L-carnitine reaction solution to be neutral by using hydrochloric acid, distilling under reduced pressure to remove unreacted trimethylamine, water and halogenated alkane, and concentrating under reduced pressure and vacuum to obtain a thick solid crude product;
C. and (3) cleaning the thick solid crude product by using fatty acid fatty ester to remove residual unreacted organic impurities, then performing vacuum concentration again under reduced pressure to obtain an L-carnitine solid product, then drying at 110 ℃ for 1 hour, removing water, and crushing to obtain powdery L-carnitine crude product.
Example 3
Taking 100g of L-carnitine crude product, adding 3% ethyl acetate and 1% ethyl propionate into 200mL of absolute ethanol, stirring for 3 hours at-30 ℃ to uniformly mix the L-carnitine crude product and the absolute ethanol, filtering to remove precipitates insoluble in the organic solvent, washing the precipitates for 4 times by using the absolute ethanol stored at 5 ℃, merging filtrate into L-carnitine solution, and removing the organic solvent by vacuum concentration under reduced pressure to obtain the pure L-carnitine product.
Through detection, the chemical purity of the L-carnitine product is 98%.
Example 4
The purification process of the crude L-carnitine is the same as in example 3.
The preparation method of the L-carnitine crude product comprises the following steps:
A. carrying out amination reaction on the intermediate (R) - (-) -4-halo-3-hydroxybutyrate and trimethylamine under the catalysis of inorganic base, and reacting in two phases formed by organic-phase halogenated alkane and water to obtain L-carnitine reaction liquid;
B. adjusting the L-carnitine reaction solution to be neutral by using a mixed solution of hydrochloric acid and nitric acid, removing unreacted trimethylamine, water and halogenated alkane by reduced pressure distillation, and then performing reduced pressure vacuum concentration to obtain a viscous solid crude product;
C. and (3) cleaning the viscous crude solid product by using fatty acid fatty ester to remove residual unreacted organic impurities, then performing vacuum concentration again under reduced pressure to obtain an L-carnitine solid product, drying at 130 ℃ for 5 hours, removing water, and crushing to obtain powdery L-carnitine crude product.
Example 5
Taking 100g of L-carnitine crude product into 500mL of anhydrous isobutanol added with 1% ethyl acetate and 2% ethyl formate, stirring for 10 hours at 10 ℃ to uniformly mix the L-carnitine crude product and the anhydrous isobutanol, filtering to remove precipitates insoluble in the organic solvent, washing the precipitates for 3 times by using the anhydrous isobutanol stored at 10 ℃, merging the filtrate into the L-carnitine solution, and performing vacuum concentration to remove the organic solvent to obtain a pure L-carnitine product;
through detection, the chemical purity of the L-carnitine product is 99%.
Example 6
The purification process of the crude L-carnitine is the same as in example 5.
The preparation method of the L-carnitine crude product comprises the following steps:
A. using L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide as a raw material, hydrolyzing the L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide with hydrogen peroxide in an alkaline aqueous solution, and fully reacting to obtain a L-carnitine reaction solution;
B. adjusting the L-carnitine reaction solution to be neutral by using hydrochloric acid, distilling under reduced pressure to remove unreacted water and halogenated alkane, and then concentrating under reduced pressure in vacuum to obtain a thick solid crude product;
C. and (3) cleaning the thick solid crude product by using fatty acid fatty ester to remove residual unreacted organic impurities, then performing vacuum concentration again under reduced pressure to obtain an L-carnitine solid product, drying at 150 ℃ for 1 hour, removing water, and crushing to obtain powdery L-carnitine crude product.
Example 7
Adding 8% methyl butyrate and dehydrated ethanol-butanol (20: 80, v/v) into 1000mL of crude L-carnitine product, stirring for 3 hours at 8 ℃ to uniformly mix the crude L-carnitine product and the dehydrated ethanol-butanol (20: 80, v/v), filtering to remove precipitates insoluble in the organic solvent, washing the precipitates for 4 times by using the ethanol-butanol (20: 80, v/v) binary mixed organic solvent stored at 0 ℃, merging the filtrate into L-carnitine solution, and performing vacuum concentration to remove the organic solvent to obtain a pure L-carnitine product;
through detection, the chemical purity of the L-carnitine product is 98%.
Example 8
The purification process of the crude L-carnitine is the same as in example 7.
The preparation method of the L-carnitine crude product comprises the following steps:
A. carrying out amination reaction on the intermediate (R) - (-) -4-halo-3-hydroxybutyrate and trimethylamine under the catalysis of inorganic base, and reacting in two phases formed by organic-phase halogenated alkane and water to obtain L-carnitine reaction liquid;
B. adjusting the L-carnitine reaction solution to be neutral by using nitric acid, removing unreacted trimethylamine, water and halogenated alkane by reduced pressure distillation, and then performing reduced pressure vacuum concentration to obtain a thick solid crude product;
C. washing the thick solid crude product with fatty acid fatty ester to remove residual unreacted organic impurities, performing vacuum concentration again under reduced pressure to obtain an L-carnitine solid product, drying at 110 ℃ for 10 hours, removing water, and crushing to obtain powdery L-carnitine crude product.
Example 9
Adding 3% butyl propionate and dehydrated ethanol-propanol-butanol (30: 50:20, v/v) into 1000mL of crude L-carnitine product, stirring at 3 deg.C for 2 hr to mix, filtering, removing precipitate insoluble in the organic solvent, washing the precipitate with dehydrated ethanol-propanol-butanol (30: 50:20, v/v) at 10 deg.C for 5 times, mixing the filtrate with L-carnitine solution, and vacuum concentrating to remove organic solvent to obtain pure L-carnitine;
through detection, the chemical purity of the L-carnitine product is 98%.
Example 10
The purification process of the crude L-carnitine is the same as in example 9.
The preparation method of the L-carnitine crude product comprises the following steps:
A. using L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide as a raw material, hydrolyzing the L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide with hydrogen peroxide in an alkaline aqueous solution, and fully reacting to obtain a L-carnitine reaction solution;
B. adjusting the L-carnitine reaction solution to be neutral by using nitric acid, removing unreacted water and halogenated alkane by reduced pressure distillation, and then performing reduced pressure vacuum concentration to obtain a thick solid crude product;
C. and (3) cleaning the thick solid crude product by using fatty acid fatty ester to remove residual unreacted organic impurities, then performing vacuum concentration again under reduced pressure to obtain an L-carnitine solid product, drying at 150 ℃ for 3 hours, removing water, and crushing to obtain powdery L-carnitine crude product.
Example 11
Adding 1% ethyl butyrate-5% propyl butyrate-4% butyl butyrate and dehydrated methanol-propanol-butanol (50: 30:20, v/v) into 1000mL of crude L-carnitine product, stirring for 10 hours at 10 ℃ to uniformly mix, filtering to remove precipitate insoluble in the organic solvent, washing the precipitate for 5 times by using the dehydrated methanol-propanol-butanol (50: 30:20, v/v) ternary mixed organic solvent stored at 10 ℃, merging filtrate into L-carnitine solution, and performing vacuum concentration to remove the organic solvent to obtain the pure L-carnitine.
The detection proves that the chemical purity of the L-carnitine product is 97%.
Example 12
The purification process of the crude L-carnitine is the same as in example 11.
The preparation method of the L-carnitine crude product comprises the following steps:
A. using L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide as a raw material, hydrolyzing the L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide with hydrogen peroxide in an alkaline aqueous solution, and fully reacting to obtain a L-carnitine reaction solution;
B. adjusting the L-carnitine reaction solution to be neutral by using a mixed solution of hydrochloric acid and nitric acid, removing unreacted water and halogenated alkane by reduced pressure distillation, and then performing reduced pressure vacuum concentration to obtain a thick solid crude product;
C. washing the thick solid crude product with fatty acid fatty ester to remove residual unreacted organic impurities, performing vacuum concentration again under reduced pressure to obtain an L-carnitine solid product, drying at 150 ℃ for 10 hours, removing water, and crushing to obtain powdery L-carnitine crude product.
Claims (10)
1. A purification and desalination method of L-carnitine crude product is characterized by comprising the following steps:
dissolving the crude L-carnitine product in a lower alkyl alcohol mixed solvent added with fatty acid fatty ester, wherein the volume-weight ratio of the mixed solvent to the weight of the crude L-carnitine product is greater than 1, stirring and mixing uniformly, filtering, removing precipitates insoluble in the organic solvent to obtain an L-carnitine solution, and removing the organic solvent by vacuum concentration to obtain the pure L-carnitine product.
2. The method for purifying and desalting the crude L-carnitine product of claim 1, which comprises the following steps: the lower alkyl alcohol is C1-C4 lower alkyl alcohol.
3. The method for purifying and desalting crude L-carnitine as claimed in claim 2, which comprises the following steps: the lower alkyl alcohol is one or more of methanol, ethanol, propanol, isopropanol, butanol or isobutanol.
4. The method for purifying and desalting crude L-carnitine as claimed in any one of claims 1 to 3, which comprises the following steps: the fatty acid fatty ester is one or more of methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl butyl ester, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate and butyl butyrate.
5. The method of claim 4, wherein the method comprises the following steps: the volume percentage concentration of the fatty acid fatty ester in the lower alkyl alcohol is 0.1-10%.
6. The method for purifying and desalting the crude L-carnitine product of claim 1, which comprises the following steps: the stirring temperature is-30 ℃ to 10 ℃, and the stirring time is 1 to 10 hours.
7. The method for purifying and desalting the crude L-carnitine product of claim 1, which comprises the following steps: washing the precipitate with lower alkyl alcohol of 0-10 deg.c for 3-5 times, merging the filtrate into L-carnitine solution, vacuum concentrating to eliminate organic solvent and obtain pure L-carnitine product.
8. The method of claim 1, wherein the method for preparing the crude L-carnitine comprises the following steps:
A. reacting the intermediate (R) - (-) -4-halo-3-hydroxybutyrate with trimethylamine under the alkaline catalysis to obtain an L-carnitine reaction solution; or L- (-) -3-cyano-2-hydroxypropyl trimethylammonium halide is used as a raw material and hydrolyzed in alkaline aqueous solution hydrogen peroxide to obtain L-carnitine reaction solution;
B. adjusting the L-carnitine reaction solution to be neutral by using inorganic acid, and removing unreacted trimethylamine, water and halogenated alkane by reduced pressure distillation to obtain a thick solid crude product;
C. and (3) cleaning the thick solid crude product by using fatty acid fatty ester to remove residual unreacted organic impurities, and drying to remove water to obtain the L-carnitine crude product.
9. The method of claim 8, wherein the method comprises the steps of: the fatty acid fatty ester is one or more of methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl butyl ester, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate and butyl butyrate.
10. The method of claim 8, wherein the method comprises the steps of: the inorganic acid in the step B is hydrochloric acid and/or nitric acid.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114031514A (en) * | 2021-11-26 | 2022-02-11 | 开原亨泰营养科技有限公司 | Method for recovering L-carnitine in electrodialysis concentrated water in L-carnitine production process |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114031514A (en) * | 2021-11-26 | 2022-02-11 | 开原亨泰营养科技有限公司 | Method for recovering L-carnitine in electrodialysis concentrated water in L-carnitine production process |
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Application publication date: 20200526 |