CN114456054A - Process for recovering L-tartaric acid from racemized mother liquor in methyldopa production - Google Patents
Process for recovering L-tartaric acid from racemized mother liquor in methyldopa production Download PDFInfo
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- CN114456054A CN114456054A CN202210164835.5A CN202210164835A CN114456054A CN 114456054 A CN114456054 A CN 114456054A CN 202210164835 A CN202210164835 A CN 202210164835A CN 114456054 A CN114456054 A CN 114456054A
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- tartaric acid
- methyldopa
- mother liquor
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- calcium sulfate
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- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 title claims abstract description 116
- 239000012452 mother liquor Substances 0.000 title claims abstract description 55
- YKFCISHFRZHKHY-NGQGLHOPSA-N (2s)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoic acid;trihydrate Chemical compound O.O.O.OC(=O)[C@](N)(C)CC1=CC=C(O)C(O)=C1.OC(=O)[C@](N)(C)CC1=CC=C(O)C(O)=C1 YKFCISHFRZHKHY-NGQGLHOPSA-N 0.000 title claims abstract description 50
- 229940083181 centrally acting adntiadrenergic agent methyldopa Drugs 0.000 title claims abstract description 50
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 29
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims abstract description 111
- 238000006243 chemical reaction Methods 0.000 claims abstract description 54
- 239000001427 calcium tartrate Substances 0.000 claims abstract description 33
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000001914 filtration Methods 0.000 claims abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 23
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000007864 aqueous solution Substances 0.000 claims abstract description 22
- 230000006340 racemization Effects 0.000 claims abstract description 22
- 235000019270 ammonium chloride Nutrition 0.000 claims abstract description 16
- 230000020477 pH reduction Effects 0.000 claims abstract description 9
- 238000004064 recycling Methods 0.000 claims abstract description 4
- 239000000243 solution Substances 0.000 claims description 14
- 239000000047 product Substances 0.000 claims description 13
- 239000012065 filter cake Substances 0.000 claims description 10
- 230000035484 reaction time Effects 0.000 claims description 4
- 238000011084 recovery Methods 0.000 abstract description 7
- 239000002920 hazardous waste Substances 0.000 abstract description 3
- 239000000463 material Substances 0.000 abstract description 3
- 238000009270 solid waste treatment Methods 0.000 abstract description 3
- 238000003912 environmental pollution Methods 0.000 abstract description 2
- 239000012295 chemical reaction liquid Substances 0.000 abstract 1
- 238000003756 stirring Methods 0.000 description 25
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 22
- 235000002906 tartaric acid Nutrition 0.000 description 19
- 239000011975 tartaric acid Substances 0.000 description 19
- 238000010438 heat treatment Methods 0.000 description 12
- 230000007062 hydrolysis Effects 0.000 description 9
- 238000006460 hydrolysis reaction Methods 0.000 description 9
- 238000006386 neutralization reaction Methods 0.000 description 9
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 8
- 238000001035 drying Methods 0.000 description 8
- 239000003456 ion exchange resin Substances 0.000 description 8
- 229920003303 ion-exchange polymer Polymers 0.000 description 8
- 238000004448 titration Methods 0.000 description 8
- XUJNEKJLAYXESH-UWTATZPHSA-N D-Cysteine Chemical compound SC[C@@H](N)C(O)=O XUJNEKJLAYXESH-UWTATZPHSA-N 0.000 description 4
- 229930195710 D‐cysteine Natural products 0.000 description 4
- 239000006227 byproduct Substances 0.000 description 4
- 239000012716 precipitator Substances 0.000 description 4
- 239000003814 drug Substances 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- UMYZWICEDUEWIM-UHFFFAOYSA-N 1-(3,4-dimethoxyphenyl)propan-2-one Chemical group COC1=CC=C(CC(C)=O)C=C1OC UMYZWICEDUEWIM-UHFFFAOYSA-N 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- 108010009736 Protein Hydrolysates Proteins 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- LEVWYRKDKASIDU-QWWZWVQMSA-N D-cystine Chemical compound OC(=O)[C@H](N)CSSC[C@@H](N)C(O)=O LEVWYRKDKASIDU-QWWZWVQMSA-N 0.000 description 1
- 229940123736 Decarboxylase inhibitor Drugs 0.000 description 1
- 206010020772 Hypertension Diseases 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000003276 anti-hypertensive effect Effects 0.000 description 1
- 238000011914 asymmetric synthesis Methods 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- GUPPESBEIQALOS-UHFFFAOYSA-L calcium tartrate Chemical compound [Ca+2].[O-]C(=O)C(O)C(O)C([O-])=O GUPPESBEIQALOS-UHFFFAOYSA-L 0.000 description 1
- 235000011035 calcium tartrate Nutrition 0.000 description 1
- GUPPESBEIQALOS-ZVGUSBNCSA-L calcium;(2r,3r)-2,3-dihydroxybutanedioate Chemical compound [Ca+2].[O-]C(=O)[C@H](O)[C@@H](O)C([O-])=O GUPPESBEIQALOS-ZVGUSBNCSA-L 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000003954 decarboxylase inhibitor Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000000413 hydrolysate Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 235000019614 sour taste Nutrition 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/02—Preparation of carboxylic acids or their salts, halides or anhydrides from salts of carboxylic acids
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/41—Preparation of salts of carboxylic acids
- C07C51/412—Preparation of salts of carboxylic acids by conversion of the acids, their salts, esters or anhydrides with the same carboxylic acid part
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
- C07B2200/00—Indexing scheme relating to specific properties of organic compounds
- C07B2200/07—Optical isomers
Abstract
The invention discloses a process for recovering L-tartaric acid from a racemized mother liquor in methyldopa production, which comprises the following steps: (1) adding calcium sulfate and ammonium chloride into the racemization mother liquor in methyldopa production, reacting the calcium sulfate with L-ammonium tartrate in the racemization mother liquor, and filtering to obtain L-calcium tartrate; (2) suspending L-calcium tartrate with water, adding sulfuric acid for acidification reaction, and filtering reaction liquid to obtain wet calcium sulfate and an aqueous solution containing L-tartaric acid; recycling the wet calcium sulfate product to the step (1); the L-tartaric acid is obtained by purifying the aqueous solution containing the L-tartaric acid and is used for producing methyldopa. The method solves the problem of environmental pollution caused by L-tartaric acid in the racemized mother liquor in methyldopa production, also solves the problem of the direction of hazardous waste calcium sulfate generated in the recovery process of the L-tartaric acid, avoids the discharge of the calcium sulfate, realizes the internal circulation of materials, and reduces the solid waste treatment cost.
Description
Technical Field
The invention relates to the field of chemical production, in particular to a process for recovering L-tartaric acid from a racemized mother liquor in methyldopa production.
Background
Methyldopa is a mammalian decarboxylase inhibitor, has an antihypertensive effect, and is currently used clinically as a medicament for treating hypertension.
The common production process of methyldopa is to take veratone (chemical name is 3, 4-dimethoxyphenyl acetone) as a starting material, react the veratone with sodium cyanide and ammonium chloride to generate DL-3- (3, 4-dimethoxyphenyl) -2-amino-2-methylpropanenitrile, DL-aminopropionitrile for short, and then split and hydrolyze by taking L-tartaric acid as a splitting agent to obtain the methyldopa. Therefore, the racemized mother liquor for producing methyldopa contains a large amount of L-tartaric acid.
Tartaric acid, 2, 3-dihydroxysuccinic acid, namely dihydroxysuccinic acid, with the molecular formula C4H6O6. Is a colorless translucent crystal with sour taste or a white fine to coarse crystalline powder. Tartaric acid is an important organic raw material, is widely applied to industries such as medicine, food, chemistry and textile, and particularly shows increasingly economic benefits in medicine and chemistry industries. Tartaric acid is used as an expensive chiral resolving agent, and in actual production, if tartaric acid in wastewater is not recycled, the environment is polluted, great resource waste is caused, and the production cost is greatly increased.
Chinese patent publication No. CN108609767A discloses a method for recycling L-tartaric acid, which comprises adding calcium chloride into wastewater to react to generate calcium tartrate precipitate, separating tartaric acid from wastewater, adding 2-4% sulfuric acid solution as solvent, stirring to react, and filtering the generated calcium sulfate from water to obtain tartaric acid solution. The method uses a large amount of calcium chloride and generates a large amount of calcium sulfate by-products, which is not in accordance with the policies of environmental protection and green economy.
Chinese patent publication No. CN113277941A discloses a method for recovering L-tartaric acid from D-cysteine conversion hydrolysate, which comprises the following steps: 1. hydrolysis neutralization of double salt: separating L-tartaric acid in the D-cysteine conversion hydrolysate by using calcium oxide as a precipitator; 2. acidifying: acidifying L-calcium tartrate with sulfuric acid, concentrating, filtering to remove calcium sulfate salt, cooling the filtrate, and crystallizing to obtain L-tartaric acid; 3. preparation of the product: the liquid after recovering the L-tartaric acid is taken as a raw material, and the D-cystine is prepared by adopting the asymmetric synthesis process of the D-cysteine in the prior art. The method uses calcium oxide as a precipitator to separate L-tartaric acid in D-cysteine conversion hydrolysate, and also generates a large amount of calcium sulfate by-products.
At present, the existing tartaric acid recovery process has high energy consumption and high cost, and generates a large amount of calcium sulfate byproducts.
Disclosure of Invention
The invention provides a process for recovering L-tartaric acid from a methyldopa production racemization mother liquor, which has the advantages of simple operation, mild reaction conditions, easy control, high purity of obtained products and high yield, solves the problem of environmental pollution caused by the L-tartaric acid in the methyldopa production racemization mother liquor, solves the problem of removal of dangerous waste calcium sulfate generated in the L-tartaric acid recovery process, avoids discharge of the calcium sulfate, realizes material internal circulation, reduces the solid waste treatment cost, has stable process, and is suitable for industrial production.
The technical scheme of the invention is as follows:
a process for recovering L-tartaric acid from a racemized mother liquor in methyldopa production comprises the following steps:
(1) adding calcium sulfate and ammonium chloride into the racemization mother liquor in methyldopa production, reacting the calcium sulfate with L-ammonium tartrate in the racemization mother liquor, and filtering to obtain a wet L-calcium tartrate product;
(2) suspending the wet L-calcium tartrate product with water, adding sulfuric acid for acidification reaction, and filtering the reaction solution to obtain a wet calcium sulfate product and an aqueous solution containing L-tartaric acid;
recycling the wet calcium sulfate product to the step (1);
(3) the L-tartaric acid aqueous solution is decolored, purified, concentrated, crystallized and dried to obtain the L-tartaric acid which is reused in the procedure of producing and splitting methyldopa. The reaction process of the invention is as follows:
in the existing tartaric acid recovery process, calcium salt with high solubility is generally adopted as a precipitator, and the generated calcium sulfate has low solubility in water and is generally treated as a hazardous waste byproduct, so that the waste of resources is caused.
The process for recovering the L-tartaric acid is a new way, but instead, the calcium sulfate is used as a precipitator, the catalytic amount of ammonium chloride is used for promoting the dissolution of the calcium sulfate into salt and then recovering the L-tartaric acid in the racemization mother liquor in the methyldopa production, and the generated calcium sulfate can be recycled.
In the step (1), in the racemized mother liquor for producing methyldopa, the mass percentage concentration of the L-ammonium tartrate is 5-20%.
In order to improve the recovery rate and purity of the L-tartaric acid, the amount of the calcium sulfate and the ammonium chloride added in the step (1) needs to be specially designed.
Preferably, in the step (1), the molar ratio of the calcium sulfate to the ammonium chloride to the L-ammonium tartrate in the racemized mother liquor for producing methyldopa is 1-1.5: 0.01-0.05: 1.
When the molar ratio is adopted, the L-ammonium tartrate in the methyldopa production racemization mother liquor can basically and completely react with the calcium sulfate, so that the recovery rate of the L-tartaric acid is improved, and the purity of the recovered L-tartaric acid is improved.
Preferably, in the step (1), the reaction temperature is 30-90 ℃; the reaction time is 1-4 h.
Preferably, the filter cake obtained in the step (1) is rinsed for multiple times by using hot water at the temperature of 30-50 ℃ to obtain a wet product of the calcium L-tartrate.
The purity of the recovered L-tartaric acid can be further improved after multiple times of washing.
In the step (2), in the acidification reaction process, the pH value of the reaction system is 0.5-1.
Preferably, in the step (2), the concentration of the sulfuric acid is 50-98%.
Preferably, in the step (2), the acidification reaction time is 0.5-1 h; the acidification reaction temperature is 50-90 ℃.
The process for recovering the L-tartaric acid from the racemized mother liquor in the methyldopa production can adopt a continuous process or an intermittent process.
Compared with the prior art, the invention has the following advantages:
(1) the process has the advantages of simple and convenient process operation, mild reaction conditions, easy control and high purity of the obtained product while improving the yield and reducing the cost.
(2) The pollution of L-tartaric acid in the racemized mother liquor in the methyldopa production to the environment is solved.
(3) The problem of the destination of hazardous waste calcium sulfate generated in the L-tartaric acid recovery process is solved, the calcium sulfate is recycled, the discharge of the calcium sulfate is avoided, the internal circulation of materials is realized, the solid waste treatment cost is reduced, the process is stable, and the method is suitable for industrial production.
Detailed Description
The technical solution of the present invention is illustrated by the following specific examples, but the scope of the present invention is not limited thereto:
example 1: small test for recovering L-tartaric acid from racemized mother liquor in methyldopa production
1. Mother liquor hydrolysis neutralization: adding 500g of methyldopa racemization mother liquor containing 5-20% of L-ammonium tartrate (converted into about 50g of L-tartaric acid, 333mmol) into a 1L three-neck flask with a thermometer and magnetons, heating the system to 40 ℃, slowly adding calcium sulfate (54.40g, 400mmol) and ammonium chloride (0.50g, 9.35mmol), starting stirring, controlling the reaction temperature to 80 ℃, and stirring for 2 hours. After the reaction, the reaction solution is filtered, and the filter cake is rinsed twice (50 ml. times.2) with hot water at 40 ℃ to obtain 123.6g of wet L-calcium tartrate.
2. Acidifying: adding 123.6g of wet L-calcium tartrate and 100ml of water into a 250ml three-neck flask with a thermometer and magnetons, starting stirring, heating a reaction system to 60 ℃, slowly adding 98% concentrated sulfuric acid until the pH value of the reaction system is 0.5-1, filtering to obtain 78.5g of wet calcium sulfate and an aqueous solution containing L-tartaric acid, removing the next batch of wet calcium sulfate for preparing L-calcium tartrate, purifying the aqueous solution containing L-tartaric acid by using ion exchange resin, concentrating until a large amount of tartaric acid is separated out, carrying out hot filtration to obtain L-tartaric acid, drying under reduced pressure to obtain 40.10g of L-tartaric acid, obtaining the yield of 80.2%, recovering the L-tartaric acid, and determining the content of 99.5% by a titration method.
Example 2: small test for recovering L-tartaric acid from racemized mother liquor in methyldopa production
1. Mother liquor hydrolysis neutralization: 500g of methyldopa racemization mother liquor (about 50g, 333mmol converted to L-tartaric acid) containing 5-20% of L-ammonium tartrate is added into a 1L three-necked bottle provided with a thermometer and magnetons, the system is heated to 40 ℃, the wet calcium sulfate (78.5 g, 392mmol) and ammonium chloride (0.50g, 9.35mmol) obtained in the operation 2 of the example 1 are slowly added, stirring is started, the reaction temperature is controlled to be 80 ℃, and stirring is carried out for 2 hours. After the reaction is finished, the solution is filtered, and a filter cake is rinsed twice (50ml multiplied by 2) by hot water with the temperature of 40 ℃ to obtain 128.7g of wet L-calcium tartrate.
2. Acidifying: adding 128.7g of wet L-calcium tartrate and 100ml of water into a 250ml three-neck flask with a thermometer and magnetons, starting stirring, heating a reaction system to 60 ℃, slowly adding 98% concentrated sulfuric acid until the pH value of the reaction system is 0.5-1, filtering to obtain 75.2g of wet calcium sulfate and an aqueous solution containing L-tartaric acid, repeatedly using the wet calcium sulfate in the next operation of preparing L-calcium tartrate, purifying the aqueous solution containing L-tartaric acid by using ion exchange resin, concentrating until a large amount of tartaric acid is separated out, carrying out hot filtration to obtain L-tartaric acid, drying under reduced pressure to obtain 39.2g of L-tartaric acid, obtaining the yield of 78.4%, and recovering the L-tartaric acid with the content of 99.7% determined by a titration method.
Example 3: small test for recovering L-tartaric acid from racemized mother liquor in methyldopa production
1. Mother liquor hydrolysis neutralization: adding 500g of methyldopa racemization mother liquor containing 5-20% of L-ammonium tartrate (converted into about 50g of L-tartaric acid, 333mmol) into a 1L three-neck flask with a thermometer and magnetons, heating the system to 40 ℃, slowly adding calcium sulfate (54.40g, 400mmol) and ammonium chloride (0.18g, 3.36mmol), starting stirring, controlling the reaction temperature to 80 ℃, and stirring for 2 hours. After the reaction is finished, the solution is filtered, and a filter cake is rinsed twice (50ml multiplied by 2) by hot water with the temperature of 40 ℃ to obtain 121.8g of wet L-calcium tartrate.
2. Acidifying: adding 121.8g of wet L-calcium tartrate and 100ml of water into a 250ml three-neck flask with a thermometer and magnetons, starting stirring, heating a reaction system to 60 ℃, slowly adding 98% concentrated sulfuric acid until the pH value of the reaction system is 0.5-1, filtering to obtain 75.9g of wet calcium sulfate and an aqueous solution containing L-tartaric acid, removing the next batch of wet calcium sulfate for preparing L-calcium tartrate, purifying the aqueous solution containing L-tartaric acid by using ion exchange resin, concentrating until a large amount of tartaric acid is separated out, carrying out hot filtration to obtain L-tartaric acid, drying under reduced pressure to obtain 38.90g of L-tartaric acid, obtaining the yield of 77.8%, and recovering the L-tartaric acid with the content of 99.8% determined by a titration method.
Example 4: small test for recovering L-tartaric acid from racemized mother liquor in methyldopa production
1. Mother liquor hydrolysis neutralization: 500g of methyldopa racemization mother liquor (about 50g, 333mmol converted to tartaric acid) containing 5-20% of L-ammonium tartrate is added into a 1L three-neck flask provided with a thermometer and magnetons, the system is heated to 40 ℃, the wet calcium sulfate (75.9 g, 392mmol) and ammonium chloride (0.18g, 3.36mmol) obtained in the operation 2 of the example 3 are slowly added, the stirring is started, the reaction temperature is controlled to be 80 ℃, and the stirring is carried out for 2 hours. After the reaction, the reaction solution is filtered, and the filter cake is rinsed twice (50 ml. times.2) with hot water at 40 ℃ to obtain 123.6g of wet L-calcium tartrate.
2. Acidifying: adding 123.6g of wet L-calcium tartrate and 100ml of water into a 250ml three-neck flask with a thermometer and magnetons, starting stirring, heating a reaction system to 60 ℃, slowly adding 98% concentrated sulfuric acid until the pH value of the reaction system is 0.5-1, filtering to obtain 83.1g of wet calcium sulfate and an aqueous solution containing L-tartaric acid, repeatedly using the wet calcium sulfate in the next operation of preparing L-calcium tartrate, purifying the aqueous solution containing L-tartaric acid by using ion exchange resin, concentrating until a large amount of tartaric acid is separated out, carrying out hot filtration to obtain L-tartaric acid, drying under reduced pressure to obtain 39.9g of L-tartaric acid, obtaining a yield of 79.8%, and recovering the L-tartaric acid with a content of 99.4% determined by a titration method.
Example 5: small test for recovering L-tartaric acid from racemized mother liquor in methyldopa production
1. Mother liquor hydrolysis neutralization: adding 500g of methyldopa racemization mother liquor containing 5-20% of L-ammonium tartrate (converted into about 50g of L-tartaric acid, 333mmol) into a 1L three-neck flask with a thermometer and magnetons, heating the system to 40 ℃, slowly adding calcium sulfate (54.40g, 400mmol) and ammonium chloride (0.89g, 11.66mmol), starting stirring, controlling the reaction temperature to 80 ℃, and stirring for 2 hours. After the reaction, the reaction solution is filtered, and the filter cake is rinsed twice (50 ml. times.2) with hot water at 40 ℃ to obtain 126.4g of wet L-calcium tartrate.
2. Acidifying: adding 126.4g of wet L-calcium tartrate and 100ml of water into a 250ml three-neck flask with a thermometer and magnetons, starting stirring, heating a reaction system to 60 ℃, slowly adding 98% concentrated sulfuric acid until the pH value of the reaction system is 0.5-1, filtering to obtain 79.8g of wet calcium sulfate and an aqueous solution containing L-tartaric acid, removing the next batch of wet calcium sulfate for preparing L-calcium tartrate, purifying the aqueous solution containing L-tartaric acid by using ion exchange resin, concentrating until a large amount of tartaric acid is separated out, carrying out hot filtration to obtain L-tartaric acid, drying under reduced pressure to obtain 41.20g of L-tartaric acid, obtaining the yield of 82.4%, and recovering the L-tartaric acid with the content of 99.8% determined by a titration method.
Example 6: small test for recovering L-tartaric acid from racemized mother liquor in methyldopa production
1. Mother liquor hydrolysis neutralization: 500g of methyldopa racemization mother liquor (about 50g, 333mmol converted to tartaric acid) containing 5-20% of L-ammonium tartrate is added into a 1L three-neck flask provided with a thermometer and magnetons, the system is heated to 40 ℃, the wet calcium sulfate (79.8 g, 392mmol) and ammonium chloride (0.89g, 11.66mmol) obtained in the operation 2 of the example 5 are slowly added, stirring is started, the reaction temperature is controlled to be 80 ℃, and stirring is carried out for 2 hours. After the reaction is finished, the solution is filtered, and a filter cake is rinsed twice (50ml multiplied by 2) by hot water with the temperature of 40 ℃ to obtain 129.2g of wet L-calcium tartrate.
2. Acidifying: adding 129.2g of wet L-calcium tartrate and 100ml of water into a 250ml three-neck flask with a thermometer and magnetons, starting stirring, heating a reaction system to 60 ℃, slowly adding 98% concentrated sulfuric acid until the pH value of the reaction system is 0.5-1, filtering to obtain 92.5g of wet calcium sulfate and an aqueous solution containing L-tartaric acid, repeatedly using the wet calcium sulfate in the next operation of preparing L-calcium tartrate, purifying the aqueous solution containing L-tartaric acid by using ion exchange resin, concentrating until a large amount of tartaric acid is separated out, carrying out hot filtration to obtain L-tartaric acid, drying under reduced pressure to obtain 42.9g of L-tartaric acid, obtaining the yield of 85.8%, and recovering the L-tartaric acid with the content of 99.2% determined by a titration method.
Example 7: small test for recovering L-tartaric acid from racemized mother liquor in methyldopa production
1. Mother liquor hydrolysis neutralization: adding 500g of methyldopa racemization mother liquor containing 5-20% of L-ammonium tartrate (converted into about 50g of L-tartaric acid, 333mmol) into a 1L three-neck flask with a thermometer and magnetons, heating the system to 40 ℃, slowly adding calcium sulfate (54.40g, 400mmol) and ammonium chloride (0.50g, 9.35mmol), starting stirring, controlling the reaction temperature to be 60 ℃, and stirring for 2 hours. After the reaction is finished, the solution is filtered, and a filter cake is rinsed twice (50ml multiplied by 2) by hot water with the temperature of 40 ℃ to obtain 129.1g of wet L-calcium tartrate.
2. Acidifying: adding 129.1g of wet L-calcium tartrate and 100ml of water into a 250ml three-neck flask with a thermometer and magnetons, starting stirring, heating a reaction system to 60 ℃, slowly adding 98% concentrated sulfuric acid until the pH value of the reaction system is 0.5-1, filtering to obtain 82.3g of wet calcium sulfate and an aqueous solution containing L-tartaric acid, removing the wet calcium sulfate for preparing L-calcium tartrate, purifying the aqueous solution containing L-tartaric acid by using ion exchange resin, concentrating until a large amount of tartaric acid is separated out, carrying out hot filtration to obtain L-tartaric acid, drying under reduced pressure to obtain 38.10g of L-tartaric acid, obtaining the yield of 76.2%, recovering the L-tartaric acid, and determining the content of 99.4% by a titration method.
Example 8: small test for recovering L-tartaric acid from racemized mother liquor in methyldopa production
1. Mother liquor hydrolysis neutralization: 500g of methyldopa racemization mother liquor (about 50g, 333mmol converted to tartaric acid) containing 5-20% of L-ammonium tartrate is added into a 1L three-neck flask provided with a thermometer and magnetons, the system is heated to 40 ℃, the wet calcium sulfate (82.3 g, 392mmol) obtained in the operation 2 of the example 7 and ammonium chloride (0.50g, 9.35mmol) are slowly added, stirring is started, the reaction temperature is controlled to be 40 ℃, and stirring is carried out for 2 hours. After the reaction, the solution is filtered, and the filter cake is rinsed twice (50 ml. times.2) with hot water of 40 ℃ to obtain 135.0g of wet L-calcium tartrate.
2. Acidifying: adding 135.0g of wet L-calcium tartrate and 100ml of water into a 250ml three-neck flask with a thermometer and magnetons, starting stirring, heating a reaction system to 60 ℃, slowly adding 98% concentrated sulfuric acid until the pH value of the reaction system is 0.5-1, filtering to obtain 71.2g of wet calcium sulfate and an aqueous solution containing L-tartaric acid, repeatedly using the wet calcium sulfate in the next operation of preparing L-calcium tartrate, purifying the aqueous solution containing L-tartaric acid by using ion exchange resin, concentrating until a large amount of tartaric acid is separated out, carrying out hot filtration to obtain L-tartaric acid, drying under reduced pressure to obtain 37.5g of L-tartaric acid, obtaining the yield of 75.0%, and recovering the L-tartaric acid with the content of 99.6% determined by a titration method.
The above-mentioned embodiments are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions, equivalents, etc. made within the scope of the principles of the present invention should be included in the scope of the present invention.
Claims (8)
1. A process for recovering L-tartaric acid from a racemized mother liquor in methyldopa production is characterized by comprising the following steps:
(1) adding calcium sulfate and ammonium chloride into the racemization mother liquor in methyldopa production, reacting the calcium sulfate with L-ammonium tartrate in the racemization mother liquor, and filtering to obtain a wet L-calcium tartrate product;
(2) suspending the wet L-calcium tartrate product with water, adding sulfuric acid for acidification reaction, and filtering the reaction solution to obtain a wet calcium sulfate product and an aqueous solution containing L-tartaric acid;
recycling the wet calcium sulfate product to the step (1);
(3) the L-tartaric acid aqueous solution is decolored, purified, concentrated, crystallized and dried to obtain the L-tartaric acid which is reused in the procedure of producing and splitting methyldopa.
2. The process for recovering L-tartaric acid from the methyldopa production racemization mother liquor according to claim 1, wherein the mass percent concentration of the L-ammonium tartrate in the methyldopa production racemization mother liquor is 5-20%.
3. The process for recovering L-tartaric acid from the methyldopa production racemization mother liquor according to claim 1, wherein in the step (1), the molar ratio of the calcium sulfate to the ammonium chloride to the L-ammonium tartrate in the methyldopa production racemization mother liquor is 1-1.5: 0.01-0.05: 1.
4. The process for recovering L-tartaric acid from the racemized mother liquor in methyldopa production according to claim 1, wherein in the step (1), the reaction temperature is 30-90 ℃; the reaction time is 1-4 h.
5. The process for recovering L-tartaric acid from the racemized mother liquor in methyldopa production according to claim 1, wherein the filter cake obtained in the step (1) is rinsed with hot water at 30-50 ℃ for multiple times to obtain a wet product of L-calcium tartrate.
6. The process for recovering L-tartaric acid from the racemized mother liquor in methyldopa production according to claim 1, wherein in the step (2), the pH value of the reaction system is 0.5-1 in the acidification reaction process.
7. The process for recovering L-tartaric acid from the racemized mother liquor in methyldopa production according to claim 1, wherein in the step (2), the concentration of the sulfuric acid is 50-98%.
8. The process for recovering L-tartaric acid from the racemized mother liquor in methyldopa production according to claim 1, wherein in the step (2), the acidification reaction time is 0.5-1 h; the acidification reaction temperature is 50-90 ℃.
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| CN102093208A (en) * | 2010-12-27 | 2011-06-15 | 常茂生物化学工程股份有限公司 | Method for producing L (+) tartaric acid |
| CN111233651A (en) * | 2020-03-17 | 2020-06-05 | 山东新华制药股份有限公司 | Method for recovering and preparing L (+) -2, 3-dihydroxysuccinic acid from polybara production wastewater |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102093208A (en) * | 2010-12-27 | 2011-06-15 | 常茂生物化学工程股份有限公司 | Method for producing L (+) tartaric acid |
| CN111233651A (en) * | 2020-03-17 | 2020-06-05 | 山东新华制药股份有限公司 | Method for recovering and preparing L (+) -2, 3-dihydroxysuccinic acid from polybara production wastewater |
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