阅读说明：本技术 一种二乙酸钠的合成方法 (Synthetic method of sodium diacetate ) 是由 姚岳平 周学文 于 2021-11-24 设计创作，主要内容包括：本发明提供一种二乙酸钠的合成方法,其包括先使冰醋酸与结晶醋酸钠或者氢氧化钠在水的存在下反应生成二乙酸钠,再将反应体系与溶媒进行混合以使二乙酸钠结晶析出,其中,溶媒为丙酮和/或乙腈。本发明通过向反应体系中加入丙酮和/或乙腈,改变反应体系的极性,从而使二乙酸钠结晶析出,不仅操作简单,而且显著提高了二乙酸钠的收率以及纯度。(The invention provides a synthesis method of sodium diacetate, which comprises the steps of firstly enabling glacial acetic acid to react with crystalline sodium acetate or sodium hydroxide in the presence of water to generate sodium diacetate, and then mixing a reaction system with a solvent to separate out the sodium diacetate crystals, wherein the solvent is acetone and/or acetonitrile. The method changes the polarity of the reaction system by adding acetone and/or acetonitrile into the reaction system, thereby crystallizing and separating out the sodium diacetate, not only having simple operation, but also obviously improving the yield and the purity of the sodium diacetate.)

1. A synthetic method of sodium diacetate is characterized by comprising the following steps: firstly, glacial acetic acid and crystalline sodium acetate or sodium hydroxide react in the presence of water to generate the sodium diacetate, and then a reaction system is mixed with a solvent to separate out the sodium diacetate crystals, wherein the solvent is acetone and/or acetonitrile.

2. The method for synthesizing sodium diacetate according to claim 1, characterized in that: the synthesis method further comprises the following steps of distilling out part of water in the reaction system before mixing the reaction system with the solvent, and then mixing the rest of the reaction system with the solvent, wherein the feeding volume ratio of the solvent to the rest of the reaction system is (1-4): 1.

3. the method for synthesizing sodium diacetate according to claim 2, characterized in that: the feeding volume ratio of the solvent to the rest of the reaction system is (1.5-2.5): 1.

4. the method for synthesizing sodium diacetate according to claim 2, characterized in that: and distilling out part of the water in the reaction system by adopting a reduced pressure distillation mode, and controlling the temperature of the reduced pressure distillation to be 60-80 ℃.

5. The method for synthesizing sodium diacetate according to claim 1, characterized in that: controlling the temperature of the crystallization to be 0-20 ℃,

and/or controlling the crystallization time to be 1-2 h.

6. The method for synthesizing sodium diacetate according to claim 1 or 2, characterized in that: the mass ratio of the glacial acetic acid to the water is 1: (2-10).

7. The method for synthesizing sodium diacetate according to claim 1, characterized in that: controlling the reaction temperature to be 50-80 ℃, and/or controlling the reaction time to be 2-4 h.

8. The method for synthesizing sodium diacetate according to claim 1, characterized in that: the feeding molar ratio of the glacial acetic acid to the crystalline sodium acetate is (1-1.2): 1, the feeding molar ratio of the glacial acetic acid to the sodium hydroxide is (2-2.5): 1.

9. the method for synthesizing sodium diacetate according to claim 1, characterized in that: the synthesis method further comprises the steps of filtering, washing and drying the sodium diacetate after the sodium diacetate is crystallized and precipitated, wherein the sodium diacetate is washed by using the solvent, and the drying temperature is controlled to be 50-70 ℃.

10. The method for synthesizing sodium diacetate according to claim 1, characterized in that: the synthesis method comprises the following steps:

(1) dissolving the crystalline sodium acetate or the sodium hydroxide in the water, adding the glacial acetic acid into a system, and reacting the crystalline sodium acetate or the sodium hydroxide with the glacial acetic acid at 50-80 ℃, wherein the charging mass ratio of the glacial acetic acid to the water is 1: (2-10);

(2) carrying out reduced pressure distillation on the system in the step (1) to remove part of water in the reaction system, wherein the mass of the distilled water is 1-6 times that of the glacial acetic acid;

(3) cooling the system in the step (2), adding the solvent with the volume amount of 1-4 times of that of the system, and crystallizing, wherein the crystallization temperature is controlled to be 0-20 ℃, and the crystallization time is 1-2 hours;

(4) and (4) filtering, washing and drying the system obtained in the step (3) to obtain the finished product of the sodium diacetate.

Technical Field

The invention belongs to the field of synthesis of fine chemical products, and particularly relates to a synthesis method of sodium diacetate.

Background

Sodium diacetate, also known as sodium diacetate, is a complex of crystalline sodium acetate and glacial acetic acid, is a white, hygroscopic crystalline solid, has the characteristics of moisture absorption and water solubility, and decomposes at temperatures above 150 ℃. The compound feed additive is mainly used as a feed additive and a food additive, is mainly used as a food mildew preventive in the food industry, and has the effects of preventing mildew, preventing corrosion, keeping freshness, improving palatability, increasing nutritive value, helping growth and the like.

The conventional synthesis method mainly uses water as a reaction solvent, after sodium diacetate is generated through reaction, a reaction system is concentrated to saturation, then the temperature is reduced to separate out sodium diacetate, and then the sodium diacetate is dried to obtain a sodium diacetate finished product. The operation is complicated by a cooling crystallization mode, and the obtained crystals can contain other impurities, so that the yield and the purity of the sodium diacetate are not high. In addition, due to the characteristics of moisture absorption and water solubility of sodium diacetate, sodium diacetate is not easy to dry at low temperature and often needs a temperature of more than 100 ℃ to be completely dried, and sodium diacetate is easy to decompose at high temperature, so that the purity of sodium diacetate is further reduced by high-temperature drying.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for synthesizing sodium diacetate with high yield, high purity and simple preparation method.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention provides a synthesis method of sodium diacetate, which comprises the steps of firstly enabling glacial acetic acid to react with crystalline sodium acetate or sodium hydroxide in the presence of water to generate the sodium diacetate, and then mixing a reaction system with a solvent to separate out the sodium diacetate crystals, wherein the solvent is acetone and/or acetonitrile.

Preferably, the synthesis method further comprises the steps of distilling off part of the water in the reaction system before mixing the reaction system with the solvent, and then mixing the rest of the reaction system with the solvent, wherein the feeding volume ratio of the solvent to the rest of the reaction system is (1-4): 1.

further preferably, the feeding volume ratio of the solvent to the rest of the reaction system is (1.5-2.5): 1.

still more preferably, the feeding volume ratio of the solvent to the rest of the reaction system is (1.5-2.0): 1.

preferably, part of the water in the reaction system is distilled out by adopting a reduced pressure distillation mode, and the temperature of the reduced pressure distillation is controlled to be 60-80 ℃.

Further preferably, the temperature of the reduced pressure distillation is controlled to be 65-75 ℃.

Preferably, the temperature of the crystallization is controlled to be 0-20 ℃.

Further preferably, the crystallization temperature is controlled to be 5-10 ℃.

Preferably, the crystallization time is controlled to be 1-2 h.

Further preferably, the crystallization time is controlled to be 1.5-2 h.

Preferably, the charging mass ratio of the glacial acetic acid to the water is 1: (2-10).

Further preferably, the charging mass ratio of the glacial acetic acid to the water is 1: (2-5).

Still further preferably, when the glacial acetic acid and the crystalline sodium acetate are used for reaction, the charging mass ratio of the glacial acetic acid to the water is 1: (4-5); when the glacial acetic acid is used for reacting with the sodium hydroxide, the charging mass ratio of the glacial acetic acid to the water is 1: (2-3).

Preferably, the reaction temperature is controlled to be 50-80 ℃.

Further preferably, the reaction temperature is controlled to be 60-70 ℃.

Preferably, the reaction time is controlled to be 2-4 h.

Further preferably, the reaction time is controlled to be 2-3 h.

Preferably, the charging molar ratio of the glacial acetic acid to the crystalline sodium acetate is (1-1.2): 1.

more preferably, the charging molar ratio of the glacial acetic acid to the crystalline sodium acetate is (1-1.1): 1.

more preferably, the charging molar ratio of the glacial acetic acid to the crystalline sodium acetate is (1.01-1.05): 1.

preferably, the feeding molar ratio of the glacial acetic acid to the sodium hydroxide is (2-2.5): 1.

further preferably, the feeding molar ratio of the glacial acetic acid to the sodium hydroxide is (2-2.3): 1.

preferably, the synthesis method further comprises the steps of filtering, washing and drying the sodium diacetate after the sodium diacetate is crystallized and precipitated, wherein the sodium diacetate is washed by using the solvent, and the drying temperature is controlled to be 50-70 ℃.

Further preferably, the drying temperature is controlled to be 50-60 ℃.

Preferably, the synthesis method comprises the following steps:

(1) dissolving the crystalline sodium acetate or the sodium hydroxide in the water, adding the glacial acetic acid into a system, and reacting the crystalline sodium acetate or the sodium hydroxide with the glacial acetic acid at 50-80 ℃, wherein the charging mass ratio of the glacial acetic acid to the water is 1: (2-10);

(2) carrying out reduced pressure distillation on the system in the step (1) to remove part of water in the reaction system, wherein the mass of the distilled water is 1-6 times that of the glacial acetic acid;

(3) cooling the system in the step (2), adding the solvent with the volume amount of 1-4 times of that of the system, and crystallizing, wherein the crystallization temperature is controlled to be 0-20 ℃, and the crystallization time is 1-2 hours;

(4) and (4) filtering, washing and drying the system obtained in the step (3) to obtain the finished product of the sodium diacetate.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the method changes the polarity of the reaction system by adding acetone and/or acetonitrile into the reaction system, thereby crystallizing and separating out the sodium diacetate, not only having simple operation, but also obviously improving the yield and the purity of the sodium diacetate.

Detailed Description

Sodium diacetate is very soluble in water, which undoubtedly increases the difficulty of separating sodium diacetate prepared using water as the reaction solvent. In the prior art, sodium diacetate is concentrated to saturation and then cooled to separate out sodium diacetate crystals, and the method has the defects of low yield, low purity and difficult drying of sodium diacetate. To solve this problem, the applicant has conducted long-term experiments and extensive research to obtain the scheme of the present application, which is further described below.

The invention provides a synthesis method of sodium diacetate, which comprises the following steps:

(1) dissolving crystalline sodium acetate or sodium hydroxide in water, adding glacial acetic acid into the system, and reacting the crystalline sodium acetate or sodium hydroxide with the glacial acetic acid to generate sodium diacetate;

(2) distilling the system of the step (1) under reduced pressure to remove part of the water in the reaction system;

(3) cooling the system in the step (2), and adding a solvent into the system for crystallization, wherein the solvent comprises acetone and/or acetonitrile;

(4) and (4) filtering, washing and drying the system obtained in the step (3) to obtain the finished product of the sodium diacetate.

This application is through adding acetone and/or acetonitrile in to the system, reduces the solubility of sodium diacetate in aqueous, makes sodium diacetate can the crystallization, has not only improved the yield and the purity of sodium diacetate, and the sodium diacetate that the crystallization was appeared is more easily by the drying moreover, has reduced the decomposition risk that the sodium diacetate is dry to be aroused. The method does not need to concentrate the system to a saturated state, not only saves energy consumption, but also avoids the problem that sodium diacetate is easy to be heated and decomposed by long-time evaporation concentration, and further improves the purity of the sodium diacetate.

In the step (1), the mass ratio of the glacial acetic acid to the water is 1: (2-10), for example, the ratio of 1: 2. 1: 3. 1: 4. 1: 5. 1: 6. 1: 7. 1: 8. 1: 9. 1: 10. the larger the mass ratio of the glacial acetic acid to the water is, the higher the probability that the crystalline sodium acetate or sodium hydroxide cannot be completely dissolved is, and the yield of the sodium diacetate is influenced; the smaller the mass ratio of the glacial acetic acid to the water, the longer the time and the energy consumption for subsequent fermentation and concentration increase are, and the method is uneconomical. The feeding mass ratio of glacial acetic acid to water in the application is preferably 1: (2-10).

Further, the charging molar ratio of the glacial acetic acid to the crystalline sodium acetate is (1-1.2): 1, for example, may be 1: 1. 1.01: 1. 1.02: 1. 1.03: 1. 1.04: 1. 1.05: 1. 1.06: 1. 1.07: 1. 1.08: 1. 1.09: 1. 1.1: 1, etc. The feeding molar ratio of the glacial acetic acid to the sodium hydroxide is (2-2.5): 1, for example, may be 2: 1. 2.1: 1. 2.2: 1. 2.3: 1. 2.4: 1. 2.5: 1.

further, the reaction temperature is controlled to be 50-80 ℃, and the reaction time is controlled to be 2-4 h. The reaction temperature is too low, and the reaction rate is reduced; the reaction temperature is too high, and the generated sodium diacetate is easy to decompose. The reaction temperature is controlled to be 50-80 ℃, so that the reaction rate is guaranteed, and the quality of the product is guaranteed.

In the step (2), the temperature of reduced pressure distillation is 60-80 ℃. The higher the temperature of reduced pressure distillation is, the more easily sodium diacetate is decomposed; the lower the temperature of the reduced pressure distillation, the water in the system cannot be distilled out. The temperature of reduced pressure distillation is controlled to be 60-80 ℃, so that the distillation rate is guaranteed, and the quality of the product is guaranteed.

Furthermore, the mass of the distilled water is 1-6 times of that of the glacial acetic acid. The more the amount of water in the system is, the more the amount of water distilled can be increased properly; the smaller the amount of water in the system, the less or no water in the system can be distilled off.

In the step (3), the feeding volume ratio of the solvent to the system in the step (2) is (1-4): 1, for example, may be 1: 1. 2: 1. 3: 1. 4: 1. the more the addition amount of the solvent is, the more sodium diacetate is easy to crystallize and precipitate from the system, but the more the addition amount of the solvent is, the cost is increased correspondingly; the smaller the amount of the solvent added, the more difficult the sodium diacetate is crystallized out of the system, and the yield of sodium diacetate is lowered. Preferably, the feeding volume ratio of the solvent to the system in the step (2) is (1-4): 1. in addition, the solvent in the present application can be recovered and used for application, and the solvent recovery mode in the present application is not limited, and may be, for example, distillation, rectification, and the like.

Further, after the reduced pressure distillation is finished, the temperature of the system is reduced, wherein the solvent can be added into the system during or after the temperature is reduced, and the temperature of crystallization is controlled to be 0-20 ℃.

In step (4) of the present application, sodium diacetate was washed with a solvent.

Further, the drying temperature is controlled to be 50-70 ℃.

The present invention will be further described with reference to the following examples. However, the present invention is not limited to the following examples. The implementation conditions adopted in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not mentioned are conventional conditions in the industry. The technical features of the embodiments of the present invention may be combined with each other as long as they do not conflict with each other.

Example 1

Adding 136g of crystalline sodium acetate and 300ml of water into a dry 500ml reaction bottle, fully stirring until the crystalline sodium acetate and the water are dissolved, then dropwise adding 63g of glacial acetic acid, controlling the pH to be 3.5-4.0, controlling the temperature to be about 65-70 ℃, carrying out reduced pressure distillation at 70 ℃ after the reaction time is 2 hours, slowly cooling the residual 180ml of reaction solution, adding 300ml of acetone within a half hour in the cooling process, cooling to 5-10 ℃, stirring for crystallization for 1.5 hours, filtering, washing with 50ml of acetone, and drying in a 60 ℃ vacuum drying oven to obtain 138g of sodium diacetate crystals. The yield thereof was found to be 97% and the content thereof was found to be 99.5%.

Example 2

Adding 136g of crystalline sodium acetate and 300ml of water into a dry 500ml reaction bottle, fully stirring until the crystalline sodium acetate and the water are dissolved, then dropwise adding 62g of glacial acetic acid, controlling the pH to be 3.5-4.0, controlling the temperature to be about 65-70 ℃, carrying out reduced pressure distillation at 70 ℃ after the reaction time is 2 hours, slowly cooling the residual 200ml of reaction solution, adding 300ml of acetonitrile within a half hour in the cooling process, cooling to 5-10 ℃, stirring for crystallization for 1.5 hours, filtering, washing with 50ml of acetonitrile, and drying in a 60 ℃ vacuum drying oven to obtain 140g of sodium diacetate crystals. The yield is 98.6%, and the content is 99.4%.

Example 3

Adding 20g of sodium hydroxide and 180ml of water into a dry 500ml reaction bottle, fully stirring until the sodium hydroxide and the water are dissolved, then dropwise adding 60g of glacial acetic acid, controlling the pH to be 3.5-4.0, controlling the temperature to be about 65-70 ℃, carrying out reduced pressure distillation at 70 ℃ after the reaction time is 2 hours, slowly cooling the residual reaction solution to obtain about 90ml of reaction solution, adding 150ml of acetone within a half hour in the cooling process, cooling to 5-10 ℃, stirring for crystallization for 1.5 hours, filtering, washing with 30ml of acetone, and drying in a 60 ℃ vacuum drying oven to obtain 68.5g of sodium diacetate crystals. The yield was 96% and the content was 99.3%.

Example 4

Adding 20g of sodium hydroxide and 180ml of water into a dry 500ml reaction bottle, fully stirring until the sodium hydroxide and the water are dissolved, then dropwise adding 61.5g of glacial acetic acid, controlling the pH to be 3.5-4.0, controlling the temperature to be about 65-70 ℃, carrying out reduced pressure distillation at 70 ℃ after the reaction time is 2 hours, slowly cooling the residual reaction solution of about 100ml, adding 150ml of acetonitrile within half an hour in the cooling process, cooling to 5-10 ℃, stirring for crystallization for 1.5 hours, filtering, washing with 30ml of acetonitrile, and drying in a 60 ℃ vacuum drying oven to obtain 69.5g of sodium diacetate crystals. The yield was 98% and the content was 99.4%.

The present invention has been described in detail in order to enable those skilled in the art to understand the invention and to practice it, and it is not intended to limit the scope of the invention, and all equivalent changes and modifications made according to the spirit of the present invention should be covered by the present invention.