CN106045879B - Method for preparing cyanoacetic acid - Google Patents
Method for preparing cyanoacetic acid Download PDFInfo
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- CN106045879B CN106045879B CN201610662675.1A CN201610662675A CN106045879B CN 106045879 B CN106045879 B CN 106045879B CN 201610662675 A CN201610662675 A CN 201610662675A CN 106045879 B CN106045879 B CN 106045879B
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- cyanoacetic acid
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- aqueous solution
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/30—Preparation of carboxylic acid nitriles by reactions not involving the formation of cyano groups
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/14—Preparation of carboxylic acid nitriles by reaction of cyanides with halogen-containing compounds with replacement of halogen atoms by cyano groups
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/32—Separation; Purification; Stabilisation; Use of additives
- C07C253/34—Separation; Purification
Abstract
The invention discloses a preparation method of cyanoacetic acid, which comprises the following steps: the method comprises the steps of carrying out cyanidation reaction on sodium chloroacetate and sodium cyanide to obtain a sodium cyanoacetate aqueous solution, adding hydrochloric acid into the sodium cyanoacetate aqueous solution for acidification, reacting to obtain a cyanoacetic acid aqueous solution, carrying out reduced pressure dehydration and removing sodium chloride in the dehydration, and then carrying out melt crystallization to achieve the purpose of multistage melt crystallization purification of the cyanoacetic acid. The invention can effectively improve the purity of the cyanoacetic acid by the process methods of cyanidation, acidification, decompression dehydration and crystallization, and does not need to add a solvent in the process of melt crystallization and purification, thereby avoiding the pollution of the solvent to the product, reducing the process of solvent recovery, saving equipment investment, and having high purity and high yield of the purified product.
Description
Technical Field
The invention relates to the technical field of chemical production, in particular to a method for preparing cyanoacetic acid.
Background
Cyanoacetic acid is an important organic synthetic raw material and a medicine and dye intermediate, and is used for manufacturing adhesives, vitamins and the like, and derivatives of methyl cyanoacetate, ethyl cyanoacetate and the like have important applications in the aspects of medicines, agriculture, new materials and the like, so the demand for high-purity cyanoacetic acid is increasingly enhanced. At present, various domestic manufacturers dehydrate the glass lining dehydration kettle for batch dehydration, and the batch dehydration has the disadvantages of complex operation, low equipment utilization rate, high steam consumption and low cyanoacetic acid yield due to long dehydration time.
Disclosure of Invention
According to the defects of the prior art, the invention provides a method for preparing cyanoacetic acid, which comprises the steps of carrying out cyanidation reaction on sodium chloroacetate and sodium cyanide to prepare a sodium cyanoacetate aqueous solution, then adding hydrochloric acid to carry out acidification reaction to obtain a mixed solution of the cyanoacetic acid and sodium chloride, carrying out reduced pressure dehydration and removing sodium chloride in the dehydration, and carrying out melt crystallization to realize the purification of the cyanoacetic acid.
The purpose of the invention is realized by the following technical scheme:
a preparation method of cyanoacetic acid is characterized by comprising the following steps:
(1) cyanidation reaction: performing a cyanidation reaction on sodium chloroacetate and sodium cyanide to generate a sodium cyanoacetate aqueous solution;
(2) and (3) acidification reaction: adding hydrochloric acid into the sodium cyanoacetate aqueous solution in the step (1) for acidification to obtain a mixed solution of cyanoacetic acid and sodium chloride;
(3) and (3) decompression dehydration: evaporating and dehydrating the mixed solution of cyanoacetic acid and sodium chloride in the step (2) under the condition of negative pressure to separate out the sodium chloride, and filtering the sodium chloride;
(4) melting and crystallizing: preheating the crystallizer by adopting a crystallizer to enable the cyanoacetic acid in the step (3) to be in a molten state, and cooling the cyanoacetic acid in the molten state to the crystallization temperature of the cyanoacetic acid at the speed of 10-20 ℃/h to enable the cyanoacetic acid to be crystallized; carrying out solid-liquid separation on the crystallized product, taking the solid-phase product as a raw material, and recovering residual liquid; heating the crystallizer to 40-45 ℃ at the speed of 2-6 ℃/h, preserving heat to partially melt the solid phase product, and taking the discharged non-crystallized mother liquor as a raw material for melting and crystallizing again; and heating the crystal obtained in the crystallizer until the crystal is completely melted to finally obtain the cyanoacetic acid crystal.
And finally, the cyanoacetic acid crystal obtained can be used as a raw material of the next-stage crystallization.
The molar ratio of the sodium chloroacetate to the sodium cyanide is 0.8-1.0: 1.0-1.2.
The molar ratio of the hydrochloric acid to the sodium cyanoacetate is 1.0-1.5 times, and the mass concentration of the hydrochloric acid is 15-35%.
In the melt crystallization process, the crystallizer is preheated to 80-90 ℃.
The invention has the advantages that: the method effectively improves the purity of the cyanoacetic acid by the process methods of cyanidation, acidification, decompression dehydration and crystallization, does not need to add a solvent in the process of melting, crystallization and purification, avoids the pollution of the solvent to the product, reduces the process of solvent recovery, saves equipment investment, and has high purity and yield of the purified product, the purity of the product reaches 99 percent, and the yield reaches 90 percent.
Detailed Description
The features of the present invention and other related features are described in further detail below by way of examples to facilitate understanding by those skilled in the art:
example 1
(1) Cyanidation reaction: dissolving 98g of chloroacetic acid (with the content of 98%) and 70g of water by stirring, and neutralizing with 258g of 30% sodium carbonate aqueous solution until the pH value is 7.0-7.5 to generate 368g of sodium chloroacetate; heating to 50 ℃, then dropwise adding 106g of sodium cyanide aqueous solution with the mass concentration of 20%, finishing the reaction when the reaction temperature reaches 110 ℃, and cooling to room temperature to obtain sodium cyanoacetate aqueous solution;
(2) and (3) acidification reaction: 206g of hydrochloric acid with the mass concentration of 15% is added into the sodium cyanoacetate aqueous solution obtained in the step (1), and 309g of mixed solution of cyanoacetic acid and sodium chloride is obtained through acidification;
(3) and (3) decompression dehydration: evaporating and dehydrating the mixed solution of cyanoacetic acid and sodium chloride obtained in the step (2) under the condition of negative pressure to separate out sodium chloride, and filtering the sodium chloride;
(4) melting and crystallizing: preheating the crystallizer to 80 ℃ by adopting a crystallizer, enabling the cyanoacetic acid in the step (3) to be in a molten state, and cooling the molten cyanoacetic acid to the crystallization temperature of the cyanoacetic acid at the speed of 10-20 ℃/h to crystallize the cyanoacetic acid; carrying out solid-liquid separation on the crystallized product, reserving the solid-phase product as a raw material, and recovering residual liquid; heating the crystallizer to 40-45 ℃ at the speed of 2-6 ℃/h, preserving the heat to partially melt the solid phase product, and taking the discharged non-crystallized mother liquor as a raw material for melting and crystallizing again; 96g of cyanoacetic acid crystals are obtained in the crystallizer, the product purity reaches 99 percent, and the yield is 90 percent.
Example 2
(1) Cyanidation reaction: dissolving 98g of chloroacetic acid (with the content of 98%) and 70g of water by stirring, and neutralizing with 258g of 30% sodium carbonate aqueous solution until the pH value is 7.0-7.5 to generate 368g of sodium chloroacetate; heating to 50 ℃, then dropwise adding 106g of sodium cyanide aqueous solution with the mass concentration of 20%, finishing the reaction when the reaction temperature reaches 110 ℃, and cooling to room temperature to obtain sodium cyanoacetate aqueous solution;
(2) and (3) acidification reaction: 154g of hydrochloric acid with the mass concentration of 35% is added into the sodium cyanoacetate aqueous solution obtained in the step (1) and is acidified to obtain 509g of a mixed solution of cyanoacetic acid and sodium chloride;
(3) and (3) decompression dehydration: evaporating and dehydrating the mixed solution of cyanoacetic acid and sodium chloride obtained in the step (2) under the condition of negative pressure to separate out sodium chloride, and filtering the sodium chloride;
(4) melting and crystallizing: preheating the crystallizer to 90 ℃ by adopting a crystallizer, enabling the cyanoacetic acid in the step (3) to be in a molten state, and cooling the molten cyanoacetic acid to the crystallization temperature of the cyanoacetic acid at the speed of 10-20 ℃/h to crystallize the cyanoacetic acid; carrying out solid-liquid separation on the crystallized product, reserving the solid-phase product as a raw material, and recovering residual liquid; heating the crystallizer to 40-45 ℃ at the speed of 2-6 ℃/h, preserving the heat to partially melt the solid phase product, and taking the discharged non-crystallized mother liquor as a raw material for melting and crystallizing again; 96g of cyanoacetic acid crystals are obtained in the crystallizer, the product purity reaches 99 percent, and the yield is 90 percent.
The process of melt crystallization in the above examples can be repeated, i.e., multi-stage crystallization is performed.
Claims (3)
1. A preparation method of cyanoacetic acid is characterized by comprising the following steps:
cyanidation reaction: performing a cyanidation reaction on sodium chloroacetate and sodium cyanide to generate a sodium cyanoacetate aqueous solution; the molar ratio of the sodium chloroacetate to the sodium cyanide is 0.8-1.0: 1.0-1.2;
and (3) acidification reaction: adding hydrochloric acid into the sodium cyanoacetate aqueous solution in the step (1) for acidification to obtain a mixed solution of cyanoacetic acid and sodium chloride; the molar ratio of the hydrochloric acid to the sodium cyanoacetate is 1.0-1.5 times, and the mass concentration of the hydrochloric acid is 15-35%;
and (3) decompression dehydration: evaporating and dehydrating the mixed solution of cyanoacetic acid and sodium chloride in the step (2) under the condition of negative pressure to separate out the sodium chloride, and filtering the sodium chloride;
melting and crystallizing: preheating the crystallizer by adopting a crystallizer to enable the cyanoacetic acid in the step (3) to be in a molten state, and cooling the cyanoacetic acid in the molten state to the crystallization temperature of the cyanoacetic acid at the speed of 10-20 ℃/h to enable the cyanoacetic acid to be crystallized; carrying out solid-liquid separation on the crystallized product, taking the solid-phase product as a raw material, and recovering residual liquid; heating the crystallizer to 40-45 ℃ at the speed of 2-6 ℃/h, preserving heat to partially melt the solid phase product, and taking the discharged non-crystallized mother liquor as a raw material for melting and crystallizing again; and heating the crystal obtained in the crystallizer until the crystal is completely melted, and finally obtaining the cyanoacetic acid crystal.
2. The method for preparing cyanoacetic acid according to claim 1, wherein: and finally obtaining cyanoacetic acid crystals as the raw material of the next-stage crystallization.
3. The method for preparing cyanoacetic acid according to claim 1, wherein: in the melt crystallization process, the crystallizer is preheated to 80-90 ℃.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610662675.1A CN106045879B (en) | 2016-08-15 | 2016-08-15 | Method for preparing cyanoacetic acid |
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| CN201610662675.1A CN106045879B (en) | 2016-08-15 | 2016-08-15 | Method for preparing cyanoacetic acid |
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| CN107793329A (en) * | 2017-10-30 | 2018-03-13 | 烟台国邦化工机械科技有限公司 | A kind of isolation and purification method of cyanoacetic acid |
| CN109535028B (en) * | 2018-11-15 | 2021-10-08 | 天津科技大学 | Method for preparing pure anilinoacetonitrile by suspension melting crystallization method |
| CN111153834B (en) * | 2019-12-30 | 2022-06-14 | 吉林省舒兰合成药业股份有限公司 | Preparation method of 1, 3-dimethyl cyanoacetylurea |
| CN111793007A (en) * | 2020-07-27 | 2020-10-20 | 河北诚信九天医药化工有限公司 | Method for continuously producing cyanoacetic acid |
| CN112679380A (en) * | 2020-12-24 | 2021-04-20 | 潍坊滨海石油化工有限公司 | Preparation method of solid cyanoacetic acid |
| CN116730866B (en) * | 2023-08-14 | 2023-10-31 | 山东新和成药业有限公司 | Preparation method of cyanoacetic acid |
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| JP3938646B2 (en) * | 2000-01-14 | 2007-06-27 | 株式会社日本触媒 | Acrylic acid production method |
| CN105294491B (en) * | 2015-11-20 | 2017-06-23 | 重庆紫光化工股份有限公司 | A kind of preparation method of cyanoacetic acid and its derivative |
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