Refining method of high-purity trichloroacetone

Abstract

The invention relates to a refining method of high-purity trichloroacetone, and belongs to the technical field of compound purification, the raw material used in the process is an industrial-grade trichloroacetone crude product with the purity of 50%-70%, in the first step, water is used as a solvent to dissolve, and then cooling crystallization is performed to obtain trichloroacetone solid; and 2, carrying out melt crystallization and heating dissolution on the obtained trichloroacetone solid, carrying out gradient cooling crystallization in a specific temperature range, and slowly heating and sweating the obtained crystal to obtain the trichloroacetone crystal with the purity of 98% or more and the yield of 80% or more (based on trichloroacetone). The method is easy and convenient to operate, safe, environmentally friendly, capable of effectively improving the purity of trichloroacetone, suitable for industrial production and capable of meeting the market requirement of high-purity trichloroacetone.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of trichloroacetone purification, in particular to a refining method of high-purity trichloroacetone. BACKGROUND

[0002] Trichloroacetone, especially high-purity trichloroacetone, has extremely wide application, and can be used for synthesis and research of anti-HIV drugs, imidazole heterocyclic compounds, polycyclic or bridged ring compounds. Trichloroacetone is also an important intermediate for producing folic acid. Folic acid, also known as vitamin M, belongs to the basic varieties of vitamins. As an anti-anemia drug, folic acid is used for treating diseases such as cell anemia and colorectal cancer. In the food and feed industries, folic acid can be used as an anti-anemia drug additive, a nutritional supplement, etc. The content of trichloroacetone directly affects the quality of folic acid. At present, the content of industrial-grade trichloroacetone is only about 50%, and in addition to trichloroacetone, there are also a certain amount of 1,3-dichloroacetone, 1,1-dichloroacetone, 1,1,1,3-tetrachloroacetone, 1,1,3,3-tetrachloroacetone and 1,1,1,3,3-pentachloroacetone and other impurities. These impurities will also participate in the reaction during the synthesis of folic acid, and it is difficult to obtain folic acid meeting the requirements of the international pharmacopoeia. At the same time, using low-purity trichloroacetone as the starting material will generate a large amount of wastewater in the synthesis and refining sections of folic acid, causing serious environmental pollution.

[0003] Patent No. CN 101768066 B discloses a preparation method of high-purity trichloroacetone, which is to use 50% purity trichloroacetone to perform first recrystallization with a hydrocarbon solvent and a polar solvent, and then perform second recrystallization with a hydrocarbon solvent and a fatty acid ester to obtain high-purity trichloroacetone with a purity of 98%. This patent obtains high-purity trichloroacetone by using organic solvents for recrystallization twice, which not only increases the cost, but also is flammable, explosive and pollutes the environment. Moreover, the solvent for the second recrystallization is a mixed solvent of a fatty acid ester and a hydrocarbon solvent. If the fatty acid ester is wrapped inside the crystal during recrystallization, it will not only affect the purity of trichloroacetone, but also seriously affect the properties of folic acid and even destroy the structure of folic acid when the wrapped solvent in trichloroacetone is used in subsequent folic acid production. Patent No. CN 106946676 B discloses a purification method of high-purity trichloroacetone for preparing folic acid. This method uses an aqueous solvent to purify and prepare high-purity trichloroacetone. In the first step, 50% purity trichloroacetone crude product is extracted three times with an aqueous solvent. In the second step, the obtained extract is recrystallized by gradient cooling. Through two steps of purification, the purity of the trichloroacetone crude product with a purity of about 50% is increased to more than 98%, and the trichloroacetone crystallization yield can reach more than 80% based on the raw material.

[0004] Therefore, it is urgent to provide a trichloroacetone purification process with simple process, convenient operation, low cost, environmental protection, high yield and high purity to meet the production needs. SUMMARY

[0005] In view of the problems of complex process, high cost, low yield and low purity in the current trichloroacetone purification process, the application provides a high-purity trichloroacetone refining method, which can increase the purity of low-purity trichloroacetone (50%-70%) to more than 98%.

[0006] The application is achieved by the following technical solutions: A high-purity trichloroacetone refining method, comprising the following steps: (1) Crystallization: industrial-grade trichloroacetone crude product with a content of 50%-70% and water are sequentially added to a beaker, stirred and dissolved, and then filtered after crystallization under cooling to obtain trichloroacetone solids; (2) Melting crystallization: the trichloroacetone solids obtained in the step (1) are dissolved by increasing the temperature, and then recrystallized by decreasing the temperature, and then filtered to obtain trichloroacetone crystals; the trichloroacetone crystals are slowly warmed and sweating until ice slurry appears, and then filtered to obtain high-purity trichloroacetone.

[0007] According to the high-purity trichloroacetone refining method, comprising the following steps: (1) Crystallization: industrial-grade trichloroacetone is added to a beaker, stirred and dissolved at room temperature, slowly cooled to crystallize, and then filtered after a large amount of crystals are precipitated, to obtain trichloroacetone solids, and the filtrate is added to the initial feeding stage as a raw material for recycling; (2) Melting crystallization: the trichloroacetone solids obtained in the step (1) are dissolved by increasing the temperature and keeping the temperature in a certain range, and then a large amount of crystals are precipitated by gradient cooling, and then filtered using a heat preservation funnel, to obtain trichloroacetone crystals, and the filtrate is added to the initial feeding stage as a raw material for recycling; The temperature of the heat preservation funnel is increased by circulating water, the trichloroacetone crystals are slowly warmed in the heat preservation funnel, and then filtered after ice slurry appears, to obtain high-purity trichloroacetone, and the filtrate is added to the initial feeding stage as a raw material for recycling.

[0008] According to the high-purity trichloroacetone refining method, the mass ratio of the industrial-grade trichloroacetone crude product to water in the step (1) is 1:0.4-2.5.

[0009] According to the high-purity trichloroacetone refining method, the dissolving temperature in the step (1) is room temperature, and the dissolving time is 0.5-3h.

[0010] According to the method for refining high-purity trichloroacetone, the cooling temperature in step (1) is -10°C-30°C, and the crystallization time is 1-5 hours.

[0011] According to the method for refining high-purity trichloroacetone, the dissolving temperature in step (2) is 40-55°C.

[0012] According to the method for refining high-purity trichloroacetone, the cooling temperature in step (2) is 5-30°C, the cooling adopts a gradient cooling method, and the cooling rate is 1-5°C / min.

[0013] According to the method for refining high-purity trichloroacetone, the crystallization time in step (2) is 2-5 hours.

[0014] According to the method for refining high-purity trichloroacetone, the filtration in step (2) is performed using an insulation funnel, and the insulation temperature of the insulation funnel is 5-30°C.

[0015] According to the method for refining high-purity trichloroacetone, the slowly heating in step (2) is performed in a heat preservation funnel, the circulating water temperature of the heat preservation funnel is 40-50° C., and the heating time is 2-15 minutes.

[0016] The beneficial effects achieved by the present invention are: The purification method of the present invention no longer uses organic solvents, thus avoiding the potential risks of flammability and explosion. The water added in the method is recycled, and no organic wastewater is generated, which is in line with the concept of green chemical industry. The present invention requires simple equipment, low production environment and operating temperature, less thermal decomposition, and significantly reduced energy consumption; The method of the present invention has high separation efficiency, high product quality, purity and safety; high yield, and is suitable for industrial large-scale purification. DETAILED DESCRIPTION

[0017] The above contents of the present invention are further described in detail below through examples, but this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above contents of the present invention fall within the scope of the present invention. Example 1

[0018] (1) Crystallization: Add 200 ml of industrial-grade trichloroacetone with a content of 58% to a 1000 ml beaker, weigh about 300 g, then add 300 ml of water, stir at room temperature for 1 hour to dissolve, then slowly cool to 0°C until crystals precipitate, continue to keep warm and stir for 3 hours until a large amount of crystals precipitate, and filter the material containing crystals to obtain trichloroacetone solid. The main component of the filtrate is trichloroacetone, which is recycled as raw water.

[0019] (2) Melt crystallization: Crystallization: The solid trichloroacetone obtained in step (1) above was warmed to 40°C and kept for a certain time to dissolve all the solid trichloroacetone, and then was gradually cooled to 28°C at a rate of 3°C / min, and kept for 3h to precipitate a large amount of crystals. A filter flask was used for filtration, and the temperature of the filter flask was kept at 28°C. The trichloroacetone crystals were obtained by filtration, and the filtrate mainly contained trichloroacetone which could be used as the raw water in step (1).

[0020] Sweating: The circulating water at 43°C was introduced into the filter flask, and the trichloroacetone crystals were slowly warmed. After about 10 min, ice slurry appeared, and the high-purity trichloroacetone 137.68 g was obtained by filtration. The water content was 1.98%, the GC content was 99.32%, and the yield was 81.28%. The filtrate mainly contained trichloroacetone which could be used as the raw water in step (1). Example 2

[0021] (1) Crystallization: In a 1000ml beaker, 200ml of industrial-grade trichloroacetone with a content of 58% was added, about 300g of water was weighed, 150ml of water was added, and stirring was performed at room temperature for 2h. The temperature was slowly lowered to 25°C until crystals precipitated, and the temperature was kept for 1.5h. A large amount of crystals precipitated, and the trichloroacetone solid was obtained by filtration. The filtrate mainly contained trichloroacetone which was used as the raw water for recycling.

[0022] (2) Melt crystallization: Crystallization: The solid trichloroacetone obtained in step (1) above was warmed to 40°C and kept for a certain time to dissolve all the solid trichloroacetone, and then was gradually cooled to 28°C at a rate of 3°C / min, and kept for 3h to precipitate a large amount of crystals. A filter flask was used for filtration, and the temperature of the filter flask was kept at 28°C. The trichloroacetone crystals were obtained by filtration, and the filtrate mainly contained trichloroacetone which could be used as the raw water in step (1).

[0023] Sweating: The circulating water at 43°C was introduced into the filter flask, and the trichloroacetone crystals were slowly warmed. After about 10 min, ice slurry appeared, and the high-purity trichloroacetone 137.68 g was obtained by filtration. The water content was 1.98%, the GC content was 99.32%, and the yield was 81.28%. The filtrate mainly contained trichloroacetone which could be used as the raw water in step (1). Example 3

[0024] (1) Crystallization: 200 ml (about 300 g) of industrial-grade trichloroacetone (content 58%) was added into a 1000 ml beaker, 450 ml of water was added, and the solution was stirred at room temperature for 0.5 h. Slowly cooled to -5°C until crystals precipitated, continue to keep stirring for 3 h, a large amount of crystals precipitated, after filtration, trichloroacetone solid was obtained, the main component of the filtrate was trichloroacetone, which was used as raw material water for recycling.

[0025] (2) Melting crystallization: Crystallization: The trichloroacetone solid obtained in the above step (1) was heated to 40°C and kept for 3 h. The gradient cooling rate was 4°C / min, and the temperature was kept at 15°C for 3 h. The trichloroacetone crystals were obtained by filtration using a cooling funnel, and the main component of the filtrate was trichloroacetone, which was used as raw material water for recycling.

[0026] Sweating: The trichloroacetone crystals were slowly warmed by circulating water at 50°C, and ice slurry appeared after about 5 min. High-purity trichloroacetone 135.42 g was obtained by filtration, the water content was 2.42%, the GC content was 99.08%, the yield was 80.51%, and the main component of the filtrate was trichloroacetone, which was used as raw material water for recycling. Example 4

[0027] (1) Crystallization: 200 ml (about 300 g) of industrial-grade trichloroacetone (content 58%) was added into a 1000 ml beaker, 450 ml of water was added, and the solution was stirred at room temperature for 0.5 h. Slowly cooled to -5°C until crystals precipitated, continue to keep stirring for 3 h, a large amount of crystals precipitated, after filtration, trichloroacetone solid was obtained, the main component of the filtrate was trichloroacetone, which was used as raw material water for recycling.

[0028] (2) Melting crystallization: Crystallization: The trichloroacetone solid obtained in the above step (1) was heated to 40°C and kept for 3 h. The gradient cooling rate was 4°C / min, and the temperature was kept at 15°C for 3 h. The trichloroacetone crystals were obtained by filtration using a cooling funnel, and the main component of the filtrate was trichloroacetone, which was used as raw material water for recycling.

[0029] Sweating: The trichloroacetone crystals were slowly warmed by circulating water at 50°C, and ice slurry appeared after about 5 min. High-purity trichloroacetone 135.42 g was obtained by filtration, the water content was 2.42%, the GC content was 99.08%, the yield was 80.51%, and the main component of the filtrate was trichloroacetone, which was used as raw material water for recycling. Example 5

[0030] (1) Crystallization: 200 ml (about 300 g) of industrial-grade trichloroacetone (content 58%) was added into a 1000 ml beaker, 240 ml of water was added, and the solution was stirred at room temperature for 2 h. Slowly cooled to 15 °C until crystals precipitated, continue to keep stirring for 2 h, a large amount of crystals precipitated, after filtration, trichloroacetone solid was obtained, the main component of the filtrate was trichloroacetone, which was used as raw material water for recycling.

[0031] (2) Melting crystallization: Crystallization: The trichloroacetone solid obtained in the above step (1) was heated to 43 °C and kept for 2.5 h. The temperature was gradually reduced to 25 °C, and a large amount of crystals precipitated. The gradient cooling rate was 2 °C / min. The filtration was performed using a thermostatic funnel, and the temperature of the thermostatic funnel was 25 °C. Trichloroacetone crystals were obtained by filtration. The main component of the filtrate was trichloroacetone, which was used as raw material water for recycling.

[0032] Sweating: The above thermostatic funnel was connected to a circulating water at 45 °C, and the trichloroacetone crystals were slowly warmed. After about 10 min, ice slurry appeared. Filtration obtained high-purity trichloroacetone 133.77 g, moisture content was 3.08%, GC content was 98.76%, yield was 81.32%. The main component of the filtrate was trichloroacetone, which was used as raw material water for recycling. Example 6

[0033] (1) Crystallization: 200 ml (about 300 g) of industrial-grade trichloroacetone (content 58%) was added into a 1000 ml beaker, 240 ml of water was added, and the solution was stirred at room temperature for 2 h. Slowly cooled to 15 °C until crystals precipitated, continue to keep stirring for 2 h, a large amount of crystals precipitated, after filtration, trichloroacetone solid was obtained, the main component of the filtrate was trichloroacetone, which was used as raw material water for recycling.

[0034] (2) Melting crystallization: Crystallization: The trichloroacetone solid obtained in the above step (1) was heated to 43 °C and kept for 2.5 h. The temperature was gradually reduced to 25 °C, and a large amount of crystals precipitated. The gradient cooling rate was 2 °C / min. The filtration was performed using a thermostatic funnel, and the temperature of the thermostatic funnel was 25 °C. Trichloroacetone crystals were obtained by filtration. The main component of the filtrate was trichloroacetone, which was used as raw material water for recycling.

[0035] Sweating: The above thermostatic funnel was connected to a circulating water at 45 °C, and the trichloroacetone crystals were slowly warmed. After about 10 min, ice slurry appeared. Filtration obtained high-purity trichloroacetone 133.77 g, moisture content was 3.08%, GC content was 98.76%, yield was 81.32%. The main component of the filtrate was trichloroacetone, which was used as raw material water for recycling. Comparative Example 1

[0036] Crystallization: In a 1000ml beaker, 200ml of about 300g of industrial grade trichloroacetone with a content of 58% was added, 300ml of water was added, and stirring was carried out at room temperature for 1h. The temperature was lowered to about 0℃, and crystals were precipitated. The temperature was continued to be lowered while stirring for 3h, and a large amount of crystals was precipitated. After filtration, trichloroacetone solid was obtained, and the main component of the filtrate was trichloroacetone.

[0037] Re-crystallization: The trichloroacetone solid obtained in the above step (1) was dissolved by being heated to 40℃, and was crystallized by being gradually cooled to 28℃ for 3h. The gradient cooling rate was 3℃ / min. Filtration was carried out using a cooling funnel, and the cooling temperature of the cooling funnel was 28℃. Trichloroacetone crystals were obtained by filtration, and the main component of the filtrate was trichloroacetone.

[0038] The trichloroacetone crystals obtained above were dissolved by being heated to 40℃, and were crystallized by being gradually cooled to 28℃ for 3h. The gradient cooling rate was 3℃ / min. Filtration was carried out using a cooling funnel, and the cooling temperature of the cooling funnel was 28℃. Trichloroacetone crystals 107.74g were obtained by filtration, the water content was 4.35%, the GC content was 99.06%, and the yield was 65.35%. The main component of the filtrate was trichloroacetone.

[0039] The embodiment of the present application adds a body temperature sweating filtration process compared with the comparative example, which effectively improves the recovery rate.

[0040] The present application provides a method for refining high-purity trichloroacetone, which is simple in operation, low in cost, suitable for industrial production, and can effectively remove metal ion impurities in the material to obtain high-purity material products.

[0041] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A method for refining high-purity trichloroacetone, characterized in that: The following steps are involved: (1) Crystallization: Add 50%-70% industrial grade trichloroacetone crude product and water into a beaker, stir and dissolve, cool and crystallize, and filter to obtain trichloroacetone solid; (2) Melt crystallization: The trichloroacetone solid obtained in the above step (1) is dissolved by heating, recrystallized by cooling, and filtered to obtain trichloroacetone crystals; the above trichloroacetone crystals are slowly heated and sweated until they become smooth and filtered to obtain high-purity trichloroacetone.

2. A method for refining high-purity trichloroacetone according to claim 1, characterized in that, (1) Crystallization: Add industrial-grade trichloroacetone to a beaker, add water and stir at room temperature to dissolve, slowly cool until crystals precipitate, continue to keep warm and stir, and filter after a large amount of crystals precipitate to obtain trichloroacetone solid. The filtrate is added as raw material to the initial feeding stage for recycling; (2) Melt crystallization: The trichloroacetone solid obtained in the above step (1) is heated and kept in a certain temperature range to dissolve, and then the temperature is gradually reduced to crystallize and a large amount of crystals are precipitated, and then filtered using an insulating funnel. The trichloroacetone crystals are filtered under the insulating funnel, and the filtrate is added as a raw material to the initial feeding stage for recycling; Circulating water is introduced into the insulating funnel to increase the temperature. The trichloroacetone crystals are slowly heated in the insulating funnel and filtered to obtain high-purity trichloroacetone after becoming shaved. The filtrate is added as a raw material to the initial feeding stage for recycling.

3. A method for refining high-purity trichloroacetone according to claim 2, characterized in that, In the step (1), the mass ratio of industrial grade trichloroacetone crude product to water is 1:0.4-2.

5.

4. A method for refining high-purity trichloroacetone according to claim 2, characterized in that, The dissolution temperature in step (1) is room temperature, and the dissolution time is 0.5-3 hours.

5. A method for refining high-purity trichloroacetone according to claim 2, characterized in that, The cooling temperature in step (1) is -10°C-30°C, and the crystallization time is 1-5 hours.

6. A method for refining high-purity trichloroacetone according to claim 2, characterized in that, The dissolving temperature in step (2) is 40-55°C.

7. A method for refining high-purity trichloroacetone according to claim 2, characterized in that: The cooling temperature in step (2) is 5-30°C, and the cooling adopts a gradient cooling method with a cooling rate of 1-5°C / min.

8. A method for refining high-purity trichloroacetone according to claim 2, characterized in that, The crystallization time in step (2) is 2-5 hours.

9. A method for refining high-purity trichloroacetone according to claim 2, characterized in that: In the step (2), the filtration is performed using a heat preservation funnel, and the heat preservation temperature of the heat preservation funnel is 5-30°C.

10. The method for purifying high-purity trichloroacetone according to claim 2, wherein: The step (2) of slowly raising the temperature is to raise the temperature in a heat preservation funnel, the circulating water temperature of the heat preservation funnel is 40-50° C., and the heating time is 2-15 minutes.