Purification method and application of sucralose-6-acetate

Abstract

The invention belongs to the technical field of sucralose production, and relates to a method for purifying sucralose-6-acetate and application of the sucralose-6-acetate. The purification method comprises the following steps: S1, adding ethyl acetate into an aqueous solution of sucralose-6-acetate, heating and extracting until the concentration of sucralose-6-acetate in the aqueous solution is lower than 0.5 g / L, combining ethyl acetate phases, concentrating, crystallizing, and carrying out solid-liquid separation to obtain a filtrate 1 and a filter cake 1; s2, adding water into the filter cake 1, dissolving, crystallizing, and carrying out solid-liquid separation to obtain filtrate 2 and a filter cake 2; s3, adding water into the filter cake 2 for dissolving, decolorizing, and carrying out solid-liquid separation to obtain filtrate 3; and S4, crystallizing the filtrate 3, and carrying out solid-liquid separation to obtain purified sucralose-6-acetate and filtrate 4. The method has the advantages of low production cost, simpler process, easy control of reaction conditions, simple equipment and the like. Particularly, under the condition that the sucralose-6-acetate solution contains many and impure impurities, the method has higher extraction efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of sucralose production, and in particular relates to a method for purifying sucralose-6-acetate and an application thereof. Background Art

[0002] Sucralose is a sweetener. The current production process of sucralose mainly includes the following five steps: (1) esterification reaction (2) chlorination reaction (3) purification of sucralose-6-acetate (4) alcoholysis reaction (5) separation and purification. In the alcoholysis process using sucralose-6-acetate as raw material, high-purity (more than 99%) sucralose-6-acetate must be used and carried out under anhydrous conditions. At this time, too many impurities will seriously affect the subsequent purification of sucralose, affect the quality of the subsequent sucralose and reduce the yield.

[0003] Chinese invention patent 201210539710.2 discloses a method for separating and purifying sucralose-6-acetate mother liquor, which obtains sucralose-6-acetate crystals through reaction stratification, extraction, decolorization, filtration, and crystallization. The invention is simple, fast, and effective, and significantly improves the purification effect.

[0004] Chinese invention patent 202210020727.0 discloses a production process for sucralose-6-acetate: a mixed solution of glacial acetic acid and a first organic solvent is added to the sucrose acetate concentrate obtained by a single distillation to obtain a white eutectic powder of sucrose-6-acetate and acetic acid; the eutectic body is uniformly dispersed in a second organic solvent, treated with an organic amine to react with acetic acid to form a stable chemical bond, and acetic acid is captured from the eutectic skeleton; the residual organic amine and the formed acetic acid-organic amine combination are washed with a second organic solvent, and after complete drying, a sucrose-6-acetate powder with a concentration of more than 99.8% is obtained; and the powder is dissolved in an N,N-dimethylformamide solution and applied to the next regioselective chlorination reaction, thereby eliminating the adverse effects of impurities on the chlorination reaction process, improving the chlorination yield, and simplifying the purification process of sucralose-6-acetate.

[0005] Chinese invention patent 202311159023.2 discloses a process for purifying sucralose-6-acetate, wherein the chlorinated neutralized liquid is separated through an evaporator and a distillation tower to remove water and 1,1,2-trichloroethane, and the solid residue is filtered to obtain a crude sucralose-6-acetate N,N-dimethylformamide solution. Fresh water and eutectic seeds are added under constant temperature conditions and fully stirred. The precipitated crystals are dried to obtain a light yellow eutectic powder; the eutectic powder is completely dissolved in water, decolorized by activated carbon, and then slowly cooled for recrystallization. After drying, a white sucralose-6-acetate dihydrate product is obtained with a purity of >99.5%.

[0006] However, the existing technology causes a large loss of sucralose-6-acetate during the purification process of sucralose-6-acetate, which is also an important reason for limiting the yield of sucralose in industrial production. Therefore, exploring a better method for purifying sucralose-6-acetate is an important topic in sucralose research. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method for purifying sucralose-6-acetate and application thereof.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] In one aspect, the present invention provides a method for purifying sucralose-6-acetate, comprising the following steps:

[0010] S1, adding ethyl acetate to the aqueous solution of sucralose-6-acetate and heating to extract until the concentration of sucralose-6-acetate in the aqueous solution is lower than 0.5 g / L, combining the ethyl acetate phases, concentrating, crystallizing, and performing solid-liquid separation to obtain filtrate 1 and filter cake 1;

[0011] S2, adding water to filter cake 1 to dissolve, stirring for crystallization, and performing solid-liquid separation to obtain filtrate 2 and filter cake 2;

[0012] S3, dissolving the filter cake 2 with water, decolorizing, and performing solid-liquid separation to obtain filtrate 3;

[0013] S4, stirring the filtrate 3 for crystallization, and separating the solid and the liquid to obtain purified sucralose-6-acetate and the filtrate 4.

[0014] Furthermore, the extraction temperature in step S1 is 50-70°C, preferably 55-65°C; more preferably 60°C.

[0015] Furthermore, the specific gravity of the solution during the crystallization process in step S1 is 1.10-1.15.

[0016] Furthermore, the amount of water added in step S2 is 2-6 times the mass of the filter cake 2, preferably 3-5 times; and more preferably 3-4 times.

[0017] Furthermore, the dissolving temperature in step S2 is 75-95°C, preferably 80-90°C; more preferably 83-87°C.

[0018] Furthermore, the crystallization temperature in step S2 is room temperature, preferably 15-35°C; more preferably 18-30°C.

[0019] Furthermore, the amount of activated carbon added during the decolorization process in step S3 is 0.5-8% of the mass of the filtrate 3; preferably 1-5%; and more preferably 1-3%.

[0020] Furthermore, the decolorization time in step S3 is 0.2-2h, preferably 0.3-1h, and more preferably 0.4-0.6h.

[0021] Furthermore, the crystallization temperature in step S4 is not higher than 0°C, preferably 0 to -10°C, and more preferably 0 to -4°C.

[0022] In some embodiments, the purification method further comprises the following steps:

[0023] The filtrate 1 is concentrated and dried, and then the filtrate 2 is added to dissolve. The obtained solution is extracted with 1,2-dichloroethane to obtain a 1,2-dichloroethane phase. The 1,2-dichloroethane phase is concentrated and dried, and then ethyl acetate is added to dissolve, oxidative hydrolysis, extraction and impurity removal, crystallization, solid-liquid separation, and the filter cake is crystallized once in ethyl acetate phase and once in water to obtain sucralose-6-acetate.

[0024] Furthermore, the oxidative hydrolysis in step S5 is: cooling, adding hydrogen peroxide, adjusting the pH to 9.5-10, and maintaining for at least 7 hours.

[0025] Furthermore, the cooling in step S5 is cooling to a temperature not exceeding 0°C, preferably 0°C.

[0026] Furthermore, the extraction in step S5 is as follows: heating and layering, extracting and washing the aqueous phase and the ethyl acetate phase respectively, combining the ethyl acetate phases and concentrating them to a specific gravity of 1.10-1.15 (40° C.).

[0027] Furthermore, the crystallization temperature in step S5 is -10-10°C, preferably -5-5°C; and more preferably -2-2°C.

[0028] Furthermore, the step of crystallizing the primary ethyl acetate phase in step S5 is the same as the crystallization in step S1.

[0029] Furthermore, the step of primary water crystallization in step S5 is the same as the crystallization in step S2.

[0030] In some embodiments, the purification method further comprises the following steps:

[0031] S5. Concentrate and dry the filtrate 1, then add the filtrate 2 to dissolve it. The obtained solution is extracted with 1,2-dichloroethane to obtain a 1,2-dichloroethane phase. The 1,2-dichloroethane phase is concentrated and dried, then added with ethyl acetate to dissolve it. Cool and add hydrogen peroxide to adjust the pH to 9.5-10, maintain for at least 7 hours, heat and separate the layers, extract and wash the aqueous phase and the ethyl acetate phase respectively, combine the ethyl acetate phases and concentrate them to a specific gravity of 1.10-1.15 (50°C), stir for crystallization, separate the solid and the liquid, and crystallize the filter cake once in the ethyl acetate phase and once in water to obtain sucralose-6-acetate.

[0032] In some embodiments, the filtrate 4 in step S4 can replace water and be used in the dissolution and / or crystallization steps.

[0033] The solid-liquid separation in the present invention includes centrifugation, suction filtration or filter press, preferably suction filtration.

[0034] In another aspect, the present invention provides application of the above purification method in the production of sucralose.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention has the advantages of low production cost, simpler process, easy control of reaction conditions, simple equipment, etc. Especially when there are many and mixed impurities in the sucralose-6-acetate solution, the present invention has higher extraction efficiency. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention in conjunction with specific examples. Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the embodiments of the present invention are for describing specific embodiments rather than for limiting the scope of protection of the present invention.

[0038] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0039] Examples 1-6

[0040] S1. Take 500 mL of an aqueous solution containing sucralose-6-acetate (the intermediate product after the chlorination stage of producing sucralose), heat it to 60°C with ethyl acetate for extraction until the concentration of sucralose-6-acetate in the aqueous solution is less than 0.5 g / L, combine the ethyl acetate phases, concentrate to a specific gravity of 1.10 to 1.15 (40°C), cool to 0°C for crystallization, and obtain filtrate 1 and filter cake 1 after suction filtration.

[0041] S2 and filter cake 1 are added with pure water in a mass ratio of 1:3-4, stirred and dissolved at 85°C, then stirred and crystallized at room temperature (15-25°C), and filtered to obtain filtrate 2 and filter cake 2.

[0042] S3. Add pure water to the filter cake 2 at a mass ratio of 1:3-4, stir and dissolve at 85°C, add activated carbon at 1-3% of the mass of the filter cake 2 after complete dissolution, decolorize for 0.5h, and filter to obtain filtrate 3.

[0043] S4, filtrate 3 is stirred for crystallization, and purified sucralose-6-acetate and filtrate 4 are obtained by suction filtration.

[0044] S5. After concentrating and drying the filtrate 1, add the filtrate 2, heat to 70°C, dissolve and extract with 50% of the total volume of 1,2-dichloroethane at room temperature, concentrate and dry the obtained 1,2-dichloroethane phase, add ethyl acetate, heat (60) to dissolve, cool to 0°C and add 20% of the total volume of hydrogen peroxide, adjust the pH to 9.5-10.0 with ammonia water, maintain the pH for at least 7h, heat at 60°C to separate layers, extract and wash the water phase and the ethyl acetate phase respectively, combine the ethyl acetate phase and concentrate to a specific gravity of 1.10-1.15, stir at 0°C for crystallization, filter with suction, and obtain the fine product of sucralose-6-acetate after the filter cake is crystallized once in the ethyl acetate phase and once in pure water.

[0045]

[0046]

[0047] Comparative Example 1

[0048] Take 500 mL of aqueous solution containing sucralose-6-acetate (take the intermediate product after the chlorination stage of sucralose production), add 600 mL of ethyl acetate, and stir and crystallize at 0°C. After the crystallization is completed, filter to obtain filter cake 1 and filtrate 1. The filtrate is phase-separated, and the upper layer is the primary ester phase and the lower layer is the primary aqueous phase. Then add an equal volume of ethyl acetate to the primary aqueous phase for extraction, and then phase-separate, the upper layer is the extracted ester phase, and the lower layer is the high brine, which is directly discharged.

[0049] Add the extracted ester phase to the primary ester phase, then add ammonia water to adjust the pH to 9.5-10, and then add hydrochloric acid to adjust the pH to 7. Separate the phases, discharge the aqueous phase, add 1.25g of activated carbon to the ester phase, and stir at 50°C for 1 hour for decolorization. After decolorization, filter and concentrate the ester phase to a B sugar concentration of 130g / L. Then stir and crystallize at 0°C for 12h. After completion, filter and the solid is crude product 2.

[0050] Add 400mL of ethyl acetate to crude product 1 and crude product 2, stir and dissolve at 70℃. After complete dissolution, crystallize at 0℃ for one hour. Filter by suction, the filtrate is esterified ethyl ester, add to the primary ester phase for concentration and drying. Add 600mL of ultrapure water to the solid, stir and dissolve at 80℃, add 1.5g of activated carbon and stir for one hour to decolorize after complete dissolution. Filter by suction. The filtrate is defatted at a temperature of 80℃ and a vacuum degree of -0.1MPa. Solids precipitate during the defatting process, dissolve at 80℃, and crystallize at room temperature after complete dissolution for 4 hours. After the end, filter by suction, and the solid is sucralose-6-acetate fine product 1.

[0051] Collect the mother liquor of crude product 2 and add 40mL 35% hydrogen peroxide. React for 12h at room temperature. After the reaction is completed, add ammonia water to adjust the pH to 9.5, then add hydrochloric acid to adjust to neutrality, then add 100mL water to wash, separate the phases, extract the first aqueous phase with 200mL ethyl acetate, use the aqueous phase as waste water, and combine the second ester phase with the first ester phase. Then wash the ester phase with 100mL water again, separate the phases, use the aqueous phase as waste water, and combine the third ester phase with the above ester phase. Concentrate the slightly ester phase and crystallize at 8-10℃. Then add 1.5 times the solid ethyl acetate to crystallize the solid again to obtain the fine product of sucralose-6-acetate.

[0052] Comparative Examples 2-6

[0053] S1. Take 500 mL of an aqueous solution containing sucralose-6-acetate (the intermediate product after the chlorination stage of producing sucralose), heat it to 60°C with ethyl acetate for extraction until the concentration of sucralose-6-acetate in the aqueous solution is less than 0.5 g / L, combine the ethyl acetate phases, concentrate to a specific gravity of 1.10 to 1.15 (40°C), cool to 0°C for crystallization, and obtain filtrate 1 and filter cake 1 after suction filtration.

[0054] S2 and filter cake 1 are added with pure water in a mass ratio of 1:3-4, stirred and dissolved at 85°C, then stirred and crystallized at room temperature (15-25°C), and filtered to obtain filtrate 2 and filter cake 2.

[0055] S3. Add pure water to the filter cake 2 at a mass ratio of 1:3-4, stir and dissolve at 85°C, add activated carbon at 1-3% of the mass of the filter cake 2 after complete dissolution, decolorize for 0.5h, and filter to obtain filtrate 3.

[0056] S4, filtrate 3 is stirred for crystallization, and purified sucralose-6-acetate and filtrate 4 are obtained by suction filtration.

[0057] S5. After concentrating and drying the filtrate 1, add the filtrate 2, heat to 70°C, dissolve and extract with 50% of the total volume of 1,2-dichloroethane at room temperature, concentrate and dry the obtained 1,2-dichloroethane phase, add ethyl acetate, heat (60) to dissolve, cool to 0°C and add 20% of the total volume of hydrogen peroxide, adjust the pH to 9.5-10.0 with ammonia water, maintain the pH for at least 7h, heat at 60°C to separate layers, extract and wash the water phase and the ethyl acetate phase respectively, combine the ethyl acetate phase and concentrate to a specific gravity of 1.10-1.15, stir at 0°C for crystallization, filter with suction, and obtain the fine product of sucralose-6-acetate after the filter cake is crystallized once in the ethyl acetate phase and once in pure water.

[0058]

[0059] It should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in the field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for purifying sucralose-6-acetate, characterized in that: The steps include: S1, adding ethyl acetate to the aqueous solution of sucralose-6-acetate and heating to extract until the concentration of sucralose-6-acetate in the aqueous solution is lower than 0.5 g / L, combining the ethyl acetate phases, concentrating, crystallizing, and performing solid-liquid separation to obtain filtrate 1 and filter cake 1; S2, adding water to filter cake 1 to dissolve, crystallize, and separate the solid and liquid to obtain filtrate 2 and filter cake 2; S3, dissolving the filter cake 2 with water, decolorizing, and performing solid-liquid separation to obtain filtrate 3; S4. Crystallize the filtrate 3 and separate the solid and liquid to obtain purified sucralose-6-acetate and filtrate 4.

2. The purification method according to claim 1, characterized in that The extraction temperature in step S1 is 50-70°C; and / or The specific gravity of the concentrated solution during the crystallization process is 1.10-1.

15.

3. The purification method according to claim 1, characterized in that The amount of water added in step S2 is 2-6 times the mass of filter cake 2; and / or The dissolving temperature is 75-95°C; and / or The crystallization temperature is room temperature.

4. The purification method according to claim 1, characterized in that The amount of activated carbon added during the decolorization process in step S3 is 0.5-8% of the mass of the filtrate 3; and / or The decolorization time is 0.2-2h.

5. The purification method according to claim 1, characterized in that: The crystallization temperature in step S4 is not higher than 0°C.

6. The purification method according to any one of claims 1 to 5, characterized in that: The following steps are also included: S5. After concentrating and drying the filtrate 1, the filtrate 2 is added to dissolve, and the obtained solution is extracted with 1,2-dichloroethane to obtain a 1,2-dichloroethane phase. After concentrating and drying the 1,2-dichloroethane phase, ethyl acetate is added to dissolve, oxidative hydrolysis is performed, extraction and impurity removal is performed, crystallization is performed, and solid-liquid separation is performed. After the filter cake is crystallized once in ethyl acetate phase and once in water phase, sucralose-6-acetate is obtained.

7. The purification method according to claim 6, characterized in that: The oxidative hydrolysis in step S5 is: cooling, adding hydrogen peroxide, adjusting the pH to 9.5-10, and maintaining for at least 7 hours; and / or The cooling is to a temperature not exceeding 0°C.

8. The purification method according to claim 6, characterized in that: The extraction in step S5 is as follows: heating and layering, extracting and washing the aqueous phase and the ethyl acetate phase respectively, combining the ethyl acetate phases and concentrating them to a specific gravity of 1.10-1.

15.

9. The purification method according to claim 6, characterized in that: The crystallization temperature in step S5 is -10-10°C.

10. Use of the purification method according to any one of claims 1 to 9 in the production of sucralose.

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