Simple and efficient acesulfame potassium continuous flow sulfonation process and application

Abstract

The invention belongs to the technical field of food additive synthesis, and particularly relates to a simple and efficient acesulfame potassium continuous flow sulfonation process and application. The process comprises the following steps: diluting an acylation intermediate with dichloromethane until the mass fraction is 18-20%, and controlling the temperature to be 15-20 DEG C; an SO3 dichloromethane solution with the SO3 mass fraction of 15% is prepared, the equivalent weight of the SO3 dichloromethane solution is 4-6 times that of the acylation intermediate, and the temperature is controlled to be 15-20 DEG C; the two materials are simultaneously pumped into a continuous flow reactor by a pump, so that the conveying is completed within the same time; after entering a continuous flow mixer, materials react at the flow speed of 6-8 m / s (SO3 dichloromethane solution) and 3-5 m / s (diluted acylation intermediate) to generate a cyclization intermediate, and the cyclization intermediate and water jointly flow into a receiving bottle through a three-way pipe. The method can be applied to food additive synthesis and acesulfame potassium industrial production, and an efficient and stable technical scheme is provided for acesulfame potassium sulfonation production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food additive synthesis, and particularly relates to a simple and efficient acesulfame potassium continuous flow sulfonation process and application. BACKGROUND

[0002] Acesulfame, also known as potassium acesulfame acid, is a widely used sweetener, and its synthesis technology has always been the focus of industry research. The existing synthesis methods mainly include four kinds: first, acetoacetamide, sulfur trioxide and potassium hydroxide are used as raw materials, this method needs to be carried out at very low temperature, and the yield is not high, which is not conducive to industrial production; second, aminosulfonic acid, triethylamine, dienone, SO3 and potassium hydroxide are used as raw materials, the reaction yield is about 69%, although it also needs lower temperature, but the overall controllability is higher, the specific process route is that aminosulfonic acid reacts with triethylamine, then reacts with dienone to generate acetoacetamido sulfonic acid triethylamine salt, and then the ring closure is carried out by SO3 to obtain a cyclization intermediate, and finally hydrolysis generates acesulfame precursor acid, since the raw materials are easy to obtain and the conditions are relatively mild, this method is adopted by most manufacturers, however, a large amount of waste acid is generated after hydrolysis, and the reaction energy consumption is high, which gradually does not meet the current green and environmental development trend, and the key to this problem lies in the reaction of the sulfonation section, therefore, reducing the SO3 equivalent of the sulfonation section and increasing the reaction temperature become the core direction of the process improvement; third, aminosulfonic acid fluorine, dienone, potassium carbonate, potassium hydroxide are used as raw materials, the yield can reach more than 90%, but the raw materials contain fluorine and have insufficient cost advantage, which limits large-scale application; fourth, acetoacetamide, potassium carbonate, fluorinated sulfuric acid fluoride and potassium hydroxide are used as raw materials, the yield is about 86%, but some raw materials are not easy to obtain and contain fluorine, which also has application limitations.

[0003] In the above-mentioned methods, the second method is widely used, but there are obvious problems in the sulfonation section: the sulfonation reaction of acesulfame is rapid and releases a large amount of heat instantaneously, the heat accumulation will cause the temperature of the system to rise, which will destroy the intermediate and the cyclization intermediate, and reduce the yield. In the conventional batch reaction, the system needs to be cooled to below -30℃ to balance the temperature, which produces high energy consumption; at the same time, the acylation intermediate and the cyclization intermediate become viscous at low temperature, the mass transfer and heat transfer effect become poor, not only causing local temperature to be too high to make the product deteriorate, but also affecting the mixing effect of the materials, further restricting the production efficiency and product quality. Therefore, a technical solution is urgently needed to effectively improve the reaction efficiency, reduce the energy consumption and improve the reaction conditions, so as to adapt to the green and environmental development requirements and promote the optimization and upgrading of acesulfame production process. SUMMARY

[0004] In view of the above deficiencies, the present application provides an improved scheme for the sulfonation section of acesulfame-K based on a small continuous flow mixer. By designing a special small continuous flow mixer, the intermediate and SO3 are mixed rapidly and fully, and the reaction product cyclization intermediate is quickly transferred to the hydrolysis area, avoiding heat accumulation and destruction, which is beneficial to the improvement of yield, and can also save the energy cost required to reduce the system temperature.

[0005] The technical scheme of the present application is: In one aspect, the present application provides a process for continuous flow sulfonation of acesulfame-K, comprising the following steps: (1) dilute the acylated intermediate with dichloromethane to a mass fraction of 18%-20%, control the temperature at 15-20℃; (2) the SO3 dichloromethane solution is 4-6 equivalents of the acylated intermediate, and the temperature is controlled at 15-20℃; (3) the diluted acylated intermediate of step (1) and the SO3 dichloromethane solution of step (2) are fed into a continuous flow reactor; (4) flow at different flow rates in the mixer and react to form a cyclization intermediate, wherein the flow rate of the SO3 dichloromethane solution in the continuous flow mixer is 6-10 m / s, and the flow rate of the diluted acylated intermediate in the continuous flow mixer is 3-5 m / s; the cyclization intermediate and water flow into a receiving bottle through a three-way pipe.

[0006] Specifically, the acylated intermediate in step (1) is diluted with dichloromethane to a mass fraction of 18%, and the storage tank is controlled at a temperature of 15℃.

[0007] Specifically, the acylated intermediate in step (1) is diluted with dichloromethane to a mass fraction of 20%, and the storage tank is controlled at a temperature of 20℃.

[0008] Specifically, the SO3 in the SO3 dichloromethane solution of step (2) has a mass fraction of 15%.

[0009] Specifically, the SO3 dichloromethane solution of step (2) is 4 equivalents of the acylated intermediate.

[0010] Specifically, the SO3 dichloromethane solution of step (2) is 6 equivalents of the acylated intermediate.

[0011] Specifically, the diluted acylated intermediate and the SO3 dichloromethane solution of step (3) are fed in the same time.

[0012] Specifically, the flow rate of the SO3 dichloromethane solution in the continuous flow mixer of step (4) is 7-8 m / s, and the flow rate of the diluted acylated intermediate in the continuous flow mixer is 3-4 m / s.

[0013] Preferably, the flow rate of the SO3 dichloromethane solution in the continuous flow mixer is 8 m / s, and the flow rate of the diluted acylated intermediate in the continuous flow mixer is 4 m / s.

[0014] In one aspect, the present application provides the use of the aforementioned process in the industrial production of Acesulfame-K.

[0015] The beneficial effects of the present application are: (1) Reducing energy consumption: No need to maintain low temperature below-30℃, avoid heat accumulation by continuous flow rapid transfer of products, greatly reduce the cooling energy consumption, save energy cost.

[0016] (2) Improving yield: Continuous flow reaction reduces the probability of intermediate destruction due to high temperature, improves mass transfer and heat transfer, avoids local deterioration, and improves the final yield of Acesulfame-K.

[0017] (3) Improve efficiency and stability: Continuous flow realizes full mixing of materials, uniform reaction, shortens the cycle and improves unit output; stable conditions reduce quality fluctuations and enhance production stability.

[0018] (4) Green and environmentally friendly: Optimize the sulfonation section to reduce side reactions and reduce waste acid production; reduce environmental impact with reduced energy consumption, in line with the trend of green chemical industry.

[0019] (5) Enhance controllability: Material flow rate, ratio, temperature and other parameters can be accurately controlled, with higher operational flexibility, facilitating process optimization and efficiency improvement. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Reaction equation for the sulfonation section in the synthesis of Acesulfame-K.

[0021] Figure 2 Process flow diagram for continuous flow sulfonation reaction of Example 1.

[0022] Figure 3 Analysis and detection map, the retention time in the figure is 5.832 min, which is the peak position of acetylsulfamidic acid, i.e. the peak position of Acesulfame-K precursor acid. DETAILED DESCRIPTION

[0023] The present application will be further clarified by the following examples, which are only a part of the present application and are not intended to limit the present application. The experimental methods used in the following examples are conventional unless otherwise specified. The materials, reagents, etc. used in the following examples are commercially available unless otherwise specified.

[0024] Example 1 A simple and efficient continuous flow sulfonation process for Acesulfame-K, the specific steps are as follows: (1) The acylated intermediate (160 g, which was acetoacetylsulfamic acid triethylate, content 46%, produced by the reaction of aminosulfonic acid, triethylamine, acetic acid and divinyl ketone) taken from the previous stage was diluted with a certain amount of dichloromethane (the mass fraction of the acylated intermediate after dilution was 18%) and placed in a storage tank, and the temperature was controlled at 15°C.

[0025] (2) The prepared SO3 dichloromethane solution (15% of SO3 was dissolved in dichloromethane) was placed in a storage tank, and the temperature was controlled at 15°C.

[0026] (3) The SO3 dichloromethane solution and the acylated intermediate were simultaneously pumped into the continuous flow reactor and made to be pumped in the same time, and they reacted to form the cyclization intermediate in the continuous flow mixer in a very short time. The flow rates of the SO3 dichloromethane solution and the acylated intermediate in the continuous flow mixer were controlled at 8 m / s and 4 m / s, respectively.

[0027] (4) The cyclization intermediate flowed into the hydrolysis area, i.e. flowed into the three-way pipe with water at the same time, and finally flowed into the receiving bottle.

[0028] Example 2 (1) The acylated intermediate (160 g, which was acetoacetylsulfamic acid triethylate, content 46%, produced by the reaction of aminosulfonic acid, triethylamine, acetic acid and divinyl ketone) taken from the previous stage was diluted with a certain amount of dichloromethane (the mass fraction of the acylated intermediate after dilution was 20%) and placed in a storage tank, and the temperature was controlled at 20°C.

[0029] (2) The prepared SO3 dichloromethane solution (15% of SO3 was dissolved in dichloromethane) was placed in a storage tank, and the temperature was controlled at 20°C.

[0030] (3) The SO3 dichloromethane solution and the acylated intermediate were simultaneously pumped into the continuous flow reactor and made to be pumped in the same time, and they reacted to form the cyclization intermediate in the continuous flow mixer in a very short time. The flow rates of the SO3 dichloromethane solution and the acylated intermediate in the continuous flow mixer were controlled at 8 m / s and 4 m / s, respectively.

[0031] (4) The cyclization intermediate flowed into the hydrolysis area, i.e. flowed into the three-way pipe with water at the same time, and finally flowed into the receiving bottle.

[0032] Comparative Example The comparative example was set according to the example 1, and the difference between the comparative example and the example 1 was shown in table 1: Table 1

[0033] Effect example The yield of the sulfonation reaction of the acesulfame precursor acid (acesulfame acid), the process energy consumption, and the reaction time.

[0034] The detection method is liquid phase analysis, and the specific detection method is as follows: the chromatographic column is SHIMADZU Shim-pack C18 column (4.6*150 mm, 5 um) 8# column; the wavelength is 227 nm; v is 10 uL; T is 40 DEG C; F is 1.0 mL / min; the sample solvent is 40% ACN aqueous solution; the A pump is 0.01 mol / L tetrabutylammonium bisulfate (TBAHS) solution (70%); the B pump is ACN (30%); and the isocratic elution is 70% A:30% B for 30 min.

[0035] The detection results are shown in Table 2: Table 2

[0036] It can be known from the results in Table 2 that the production efficiency of the method used in the embodiment of the present application is greatly improved, the reaction time is shortened to 1 / 10 of the traditional process, the yield of the reaction after sulfonation and hydrolysis can reach 80%-85%, which is greatly improved compared with the traditional process, and the analysis detection spectrum is shown in Figure 3 At the same time, this means that the amount of SO3 used can be reduced by about 10% under the condition that the yield is unchanged, and the energy consumption will also be reduced.

[0037] The above detailed description is a specific description of one feasible embodiment of the present application, and the embodiment is not used to limit the patent scope of the present application. It should be noted that any equivalent implementation or change made without departing from the present application should be included in the scope of the technical scheme of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A continuous flow sulfonation process for acesulfame potassium, characterized in that, Includes the following steps: (1) Dilute the acylation intermediate with dichloromethane to a mass fraction of 18%-20% and control the temperature at 15℃-20℃; (2) SO3 dichloromethane solution is 4-6 equivalents of acylation intermediate, temperature controlled at 15℃-20℃; (3) The diluted acylation intermediate from step (1) and the SO3 dichloromethane solution from step (2) are fed into a continuous flow reactor; (4) The cyclization intermediate is generated by flowing and reacting at different flow rates in the mixer. The flow rate of SO3 dichloromethane solution in the continuous flow mixer is 6-10 m / s, and the flow rate of diluted acylated intermediate in the continuous flow mixer is 3-5 m / s. The cyclization intermediate and water flow into the receiving bottle through a three-way pipe.

2. The process according to claim 1, characterized in that, The acylation intermediate in step (1) is diluted with dichloromethane to a mass fraction of 18%, and the storage tank temperature is controlled at 15°C.

3. The process according to claim 1, characterized in that, The acylation intermediate in step (1) is diluted with dichloromethane to a mass fraction of 20%, and the storage tank is kept at a temperature of 20°C.

4. The process according to claim 1, characterized in that, The SO3 mass fraction in the dichloromethane solution in step (2) is 15%.

5. The process according to claim 1, characterized in that, The SO3 dichloromethane solution in step (2) is 4 equivalents of the acylation intermediate.

6. The process according to claim 1, characterized in that, The SO3 dichloromethane solution in step (2) is 6 equivalents of the acylation intermediate.

7. The process according to claim 1, characterized in that, In step (3), the diluted acylated intermediate and SO3 dichloromethane are dissolved and beaten within the same time period.

8. The process according to claim 1, characterized in that, In step (4), the flow rate of the SO3 dichloromethane solution in the continuous flow mixer is 7-8 m / s, and the flow rate of the diluted acylated intermediate in the continuous flow mixer is 3-4 m / s.

9. The process according to claim 8, characterized in that, In step (4), the flow rate of the SO3 dichloromethane solution in the continuous flow mixer is 8 m / s, and the flow rate of the diluted acylated intermediate in the continuous flow mixer is 4 m / s.

10. The application of the process according to any one of claims 1-9 in the industrial production of acesulfame potassium.

Images