WO2022246867A1

WO2022246867A1 - Acesulfame potassium preparation method

Info

Publication number: WO2022246867A1
Application number: PCT/CN2021/097015
Authority: WO
Inventors: 周睿; 丁震; 陈永旭; 杨峰宝; 刘刚
Original assignee: 安徽金禾实业股份有限公司
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2022-12-01
Also published as: CN113508110A; CN113508110B

Abstract

Provided is an acesulfame potassium preparation method, comprising: using an acetoacetamide-N-sulfonic acid triethylamine salt solution as a working fluid, and dissolving sulfur trioxide in a solvent to form a cyclizing agent solution as a driving fluid; introducing the working fluid from a nozzle of a Venturi reactor, introducing the driving fluid from an air suction chamber of the Venturi reactor, and controlling the pressure of the working fluid to be higher than that of the driving fluid; mixing the working fluid and the driving fluid in a mixing section and a diffusion section of the Venturi reactor, performing sulfonation cyclization reaction, and spraying a sulfonation cyclization product into a flow reactor; performing hydrolysis reaction on the sulfonation cyclization product and a hydrolysis agent preset in the flow reactor to obtain a hydrolysis product solution; and adding potassium hydroxide into the organic phase of the hydrolysis product solution to obtain acesulfame potassium. The preparation method reduces the probability that organic impurities remaining in the final product acesulfame potassium, improves the purity of acesulfame potassium, and is suitable for large-scale industrial production.

Description

The preparation method of acesulfame potassium

technical field

The invention belongs to the technical field of fine chemical manufacturing, and in particular relates to a preparation method of acesulfame potassium.

Background of the invention

Acesulfame potassium (acesulfame potassium), also known as AK sugar, is a widely used sugar substitute food additive. Its appearance is white crystalline powder. As an organic synthetic salt, its taste is similar to sugarcane, and it is easily soluble in water. , Slightly soluble in alcohol, its chemical properties are stable, and it is not easy to break down and fail; it does not participate in the body's metabolism and does not provide energy; it has high sweetness and low price; it has no cariogenicity; it has good stability to heat and acid.

At present, in the synthesis of acesulfame potassium, the diketene-sulfur trioxide method is widely used. The specific reaction steps include: reacting sulfamic acid with amine to form amine sulfamic acid salt, and then reacting amine sulfamic acid with diketene , forming acetylacetamide salt; in the presence of sulfur trioxide, acetylacetamide salt undergoes a cyclization reaction to form a cyclic sulfur trioxide adduct; the cyclic compound is hydrolyzed to obtain the hydrolyzate (ASH); subsequent oxidation with hydrogen Potassium treatment of the hydrolyzate yields acesulfame potassium (ASK).

In the step of sulfonation ring closure reaction, usually acetoacetamide salt and sulfur trioxide are directly added to the reactor for reaction, such reaction efficiency is not high, and some impurities similar in structure to acesulfame potassium will remain in the In the final product acesulfame potassium, and the reaction yield cannot reach a satisfactory level.

Although some improved technical methods for the steps of the above sulfonation ring closure reaction are disclosed in the prior art, such as Chinese patent CN103613566B, Chinese patent CN111511724A and Chinese patent CN112110876A. However, these technologies still cannot effectively improve the conversion rate of the reaction, and at the same time, they cannot solve the problem that the product (ASH) obtained after hydrolysis of the cyclization and cyclization product has many impurities.

Contents of the invention

In view of the above problems, the present application is proposed in order to provide a method for preparing acesulfame potassium that overcomes the above problems or at least partially solves the above problems.

According to the first aspect of the present application, a kind of preparation method of acesulfame potassium is provided, the method adopts combined reactor to implement, and combined reactor comprises Venturi reactor and flow reactor, the diffuser section of Venturi reactor The outlet is connected to the inlet of the flow reactor; the method comprises:

Sulfonated cyclization step: use acetoacetamide-N-sulfonic acid triethylamine salt solution as working fluid, dissolve sulfur trioxide in solvent to form cyclizing agent solution as injection fluid; working fluid from Venturi reactor The nozzle enters, and the injection fluid enters from the suction chamber of the Venturi reactor, and the pressure of the working fluid is controlled to be higher than the pressure of the injection fluid; the working fluid and the injection fluid are in the mixing section and the diffuser section of the Venturi reactor mixing and performing a sulfonation ring closure reaction, and spraying the sulfonation ring closure product into the flow reactor;

Hydrolysis step: the sulfonated cyclization product undergoes a hydrolysis reaction with a hydrolysis agent preset in the flow reactor to obtain a hydrolyzate solution; and

Salt-forming step: adding potassium hydroxide to the organic phase of the hydrolyzate solution to obtain acesulfame potassium.

Optionally, in the above method, the pressure of the working fluid is 0.4-1.6 MPa, the pressure of the injection fluid is 0.2-1.4 MPa, and the pressure of the working fluid is 0.2-0.4 MPa higher than the pressure of the injection fluid.

Optionally, in the above method, in the sulfonation and cyclization step, spraying the sulfonation and cyclization product into the flow reactor includes:

The sulfonated cyclization product is sprayed from the outlet of the diffuser section of the Venturi reactor at a pressure of 0.5-1.1 MPa, and sprayed into the flow reactor.

Optionally, in the above method, in the step of sulfonation and cyclization, the temperature of the working fluid and the injection fluid is maintained at -35°C to 0°C, preferably -15°C to 0°C.

Optionally, in the above method, in the hydrolysis step, the reaction temperature of the hydrolysis reaction is -40°C to 0°C, preferably -20°C to 0°C.

Optionally, in the above method, the hydrolysis agent is an aqueous ethanol solution, wherein the mass fraction of ethanol in the aqueous ethanol solution is 60-85%.

Optionally, in the above method, the ratio of the molar mass of sulfur trioxide to the molar mass of water in the hydrolyzing agent is 1:1-1.5.

Optionally, in the above method, the acetoacetamide-N-sulfonic acid triethylamine salt solution is prepared by the following method:

Add triethylamine in the sulfamic acid solution, carry out amination reaction, generate sulfamic acid ammonium salt solution; add diketene to the obtained sulfamic acid ammonium salt solution, under the action of solid acidic catalyst, carry out acylation reaction, obtain Acetoacetamide-N-sulfonic acid triethylamine salt solution.

Optionally, in the above method, the solid acidic catalyst is a molecular sieve catalyst or a solid superacid catalyst.

Optionally, in the above method, the molecular sieve catalyst is HZSM-5 molecular sieve and/or Na-ZSM-5 molecular sieve; the solid superacid catalyst is SO ₄ ²⁻ /Fe ₂ O ₃ type catalyst.

The beneficial effects of the present application are that the present application forms a set of combined continuous reactors by using the Venturi reactor in conjunction with the flow reactor, and on the combined reactor, by controlling acetoacetamide-N-sulfonic acid triethyl The relative pressure of the working fluid formed by the amine salt solution and the injection fluid formed by dissolving sulfur trioxide in the solvent into the Venturi reactor makes the cyclization process of acetoacetamide-N-sulfonic acid triethylamine salt and sulfur trioxide It can be completely carried out in the mixing section and diffuser section of the Venturi reactor, which greatly shortens the reaction time of the cyclization reaction, reduces the probability of organic impurities remaining in the final product acesulfame potassium, and improves the acesulfame potassium. The purity simplifies the post-treatment process of acesulfame potassium and reduces the production cost of acesulfame potassium; at the same time, the reaction can be carried out continuously, which is suitable for large-scale industrial production and improves the production efficiency of acesulfame potassium.

The above description is only an overview of the technical solution of the present application. In order to better understand the technical means of the present application, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and understandable , the following specifically cites the specific implementation manner of the present application.

Modes of Carrying Out the Invention

Exemplary embodiments of the present application will be described in more detail below. It should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided for thorough understanding of this application, and to fully convey the scope of this application to those skilled in the art.

The idea of the present application is that, in the process of preparing acesulfame potassium by using diketene-sulfur trioxide method in the prior art, in the step of sulfonation ring closure reaction, due to the low reaction efficiency, the yield of acesulfame potassium is low and there are many impurities. To solve the problem, a method for combining the Venturi reaction with a flow reactor is provided, and by controlling the reaction conditions, the above-mentioned technical defects are effectively overcome, and the method can realize continuous reaction and is suitable for large-scale industrial production.

The preparation method of acesulfame potassium provided by the application is implemented by a combined reactor, the combined reactor includes a Venturi reactor and a flow reactor, and the outlet of the diffuser section of the Venturi reactor is connected with the inlet of the flow reactor.

Fig. 1 is a schematic cross-sectional structure diagram of a Venturi reactor 100 according to an embodiment of the present application, as can be seen from Fig. The mixing effect between the jets has an important influence. As shown in Figure 1, the Venturi reactor is mainly composed of nozzle 1, suction chamber 2, mixing section 3, and diffuser section 4.

The preparation method of acesulfame potassium provided by the application is carried out using the above-mentioned Venturi reactor, the difference is that the Venturi reactor of the application is connected to a flow reactor, and by controlling the reaction conditions, the sulfonation The ring closure step is completely carried out in the mixing section 3 and the diffuser section 4 of the Venturi reactor 100 .

Specifically, the preparation method of acesulfame potassium provided in this application at least includes step S110 to step S130:

Sulfonated cyclization step S110: using acetoacetamide-N-sulfonic acid triethylamine salt solution as the working fluid, dissolving sulfur trioxide in the solvent to form a cyclizing agent solution as the injector fluid; the working fluid reacts from the Venturi The injection fluid enters from the nozzle of the Venturi reactor, and the pressure of the working fluid is controlled to be higher than the pressure of the injection fluid; the working fluid and the injection fluid are mixed and diffused in the Venturi reactor. Section mixing and sulfonation cyclization reaction, and the sulfonation cyclization product is sprayed into the flow reactor.

The principle is: the working fluid with higher pressure is compressed and accelerated through the nozzle 1, and the pressure energy is converted into kinetic energy, forming a high-speed and low-pressure area near the outlet of the nozzle 1, and then forming a pressure difference between the inlet and outlet of the suction chamber 2. Under the action of the pressure difference, the injection fluid is sucked into the mixing section through the suction chamber 2. At the entrance of the mixing section 3, the momentum and energy of the working fluid and the ejection fluid begin to exchange with each other, and due to the shearing effect of the high-speed working fluid, the sucked ejection fluid can be broken, which promotes the mutual mixing between the two phases and increases The two-phase contact area is conducive to the mass transfer of the two phases, thereby speeding up the reaction rate, and then the fully mixed two-phase fluid is decelerated and pressurized through the diffuser section, and the kinetic energy is converted into pressure energy, which can be sprayed into the outlet connected to the diffuser section 4 Inside the reactor.

In this step, acetoacetamide-N-sulfonic acid triethylamine salt reacts completely with sulfur trioxide to form a sulfonated ring closure product. The Venturi reactor sprays the sulfonated cyclization product onto the surface of the hydrolyzing agent in the flow reactor.

The use of the Venturi reactor and the setting of working parameters ensure the rapid reaction of acetoacetamide-N-sulfonic acid triethylamine salt and sulfur trioxide, so that the sulfonation ring closure reaction can be completed within 1-15s. It is best to complete the reaction within 1-3s. The short-time reaction reduces the reaction by-products and significantly reduces the impurity content.

Hydrolysis step S120: the sulfonated cyclization product undergoes a hydrolysis reaction with a hydrolysis agent preset in the flow reactor to obtain a hydrolyzate solution.

The sulfonated cyclization product undergoes hydrolysis reaction with the hydrolysis agent preset in the flow reactor. After the cyclization product is hydrolyzed, it becomes the precursor ASH of acesulfame potassium, which is different from the hydrolysis reaction using acidic solution in the traditional process. This application uses a hydrolysis agent, which can shorten the hydrolysis time. With the reduction of the hydrolysis time, the hydrolysis may produce reduction of impurity content. In some embodiments of the present application, the hydrolyzing agent is water or an aqueous ethanol solution, which significantly reduces the content of impurities in the cyclization product ASH, reduces the difficulty of subsequent purification of acesulfame potassium, and reduces the cost of purification of acesulfame potassium.

Moreover, the present application adopts a flow reactor, so that the preparation of acesulfame-K realizes continuity, and is suitable for large-scale process production.

Salt forming step S130: adding potassium hydroxide to the organic phase of the hydrolyzate solution to obtain acesulfame potassium.

After the sulfonated cyclization product is hydrolyzed, potassium hydroxide or aqueous potassium hydroxide solution is usually used to carry out a salt-forming reaction with the hydrolyzed product, thereby obtaining acesulfame potassium (ASK). The so-called salt-forming reaction refers to the process in which the cation of potassium hydroxide is exchanged with the anion of the hydrolyzate to generate the potassium salt of acesulfame.

In some embodiments of the present application, a salt-forming agent can be used instead of traditional potassium hydroxide or potassium hydroxide aqueous solution to carry out a salt-forming reaction, and inorganic impurities include but are not limited to potassium fluoride, potassium sulfate, etc. In ethanol solution, during the reaction of the sulfonated cyclization product in the organic phase with the salt-forming agent, the inorganic impurities are all dissolved in the water phase and will not be brought into the final product acesulfame potassium; in addition, the salt-forming agent To neutralize the acid ASH corresponding to acesulfame potassium, in this process, the possible chloride of acetoacetamide and acesulfame potassium is favorably reduced, thereby blocking the source of inorganic impurities during the salt formation process source, thereby improving the purity of the final product acesulfame potassium, and simplifying the follow-up process to the crude product of acesulfame potassium, reducing the cost of purifying the crude product of acesulfame potassium. In some embodiments of the present application, the salt-forming agent includes, but is not limited to, an ethanol solution of potassium hydroxide or an ethanol solution of potassium ethoxide.

In summary, the application forms a set of combined continuous reactors by using the Venturi reactor in combination with the flow reactor, and on the combined reactor, by controlling the acetoacetamide-N-sulfonic acid triethylamine salt The relative pressure of the working fluid formed by the solution and the injection fluid formed by dissolving sulfur trioxide in the solvent into the Venturi reactor makes the cyclization process of acetoacetamide-N-sulfonic acid triethylamine salt and sulfur trioxide possible in The mixing section and the diffuser section of the Venturi reactor are completely carried out, which greatly shortens the reaction time of the cyclization reaction, reduces the probability of organic impurities remaining in the final product acesulfame potassium, and improves the purity of acesulfame potassium. The post-treatment process of acesulfame potassium is simplified, and the production cost of acesulfame potassium is reduced; at the same time, the reaction can be carried out continuously, which is suitable for large-scale industrial production, and the production efficiency of acesulfame potassium is improved.

fluid working pressure

In some embodiments of the present application, the pressure of the working fluid and the injection fluid and the pressure difference between the two are not limited, and it is sufficient to control the pressure of the working fluid to be higher than the pressure of the injection fluid; in other embodiments , the pressure of the working fluid is 0.4-1.6MPa, the pressure of the injection fluid is 0.2-1.4MPa, and the pressure of the working fluid is 0.2-0.4MPa higher than the pressure of the injection fluid.

By controlling the pressure and pressure difference of the working fluid and the injection fluid, the purpose of controlling the mixing speed, reaction speed and dosage ratio of the two is achieved, so that the two can be fully and quickly mixed and reacted, and the dosage ratio of the two is controlled at an appropriate level. In the range.

Conditions of injection of sulfonated cyclization product into flow reactor

In some embodiments of the present application, there is no limitation on the conditions for spraying the sulfonated cyclization product into the flow reactor, as long as the sulfonated cyclization product can be sprayed into the flow reactor efficiently and quickly. In other embodiments of the present application, the sulfonated ring closure product is sprayed from the outlet of the diffuser section of the Venturi reactor at a pressure of 0.5-1.1 MPa, and sprayed into the flow reactor.

In the same way, by controlling the injection pressure of the sulfonated cyclization product, the purpose of controlling the dosage ratio of the sulfonated cyclization product and the hydrolyzing agent can be achieved, so that the mixing speed and dosage ratio of the two are in a more reasonable range, and the The reaction is too fast, resulting in insufficient hydrolysis.

Sulfonation ring closure reaction temperature

In some embodiments of the present application, the reaction temperature of the sulfonation cyclization step is not limited, and prior art may be referred to; in other embodiments of the present application, in the sulfonation cyclization step, the working fluid and the primer The temperature of the injection fluid is between -35°C and 0°C. In some other embodiments, it is preferable to maintain the temperature of the working fluid and the ejection fluid between -15°C and 0°C.

Because the sulfonation ring reaction of acetoacetamide-N-sulfonic acid triethylamine salt and sulfur trioxide is an exothermic reaction, thereby it is more suitable to carry out at low temperature, and the reaction environment of low temperature is conducive to suppressing the generation of side reactions, reducing the content of impurities in the product.

Types of hydrolyzing agents and hydrolysis reaction conditions

In some embodiments of the present application, in the above method, the hydrolyzing agent is deionized water or an aqueous ethanol solution, preferably an aqueous ethanol solution, wherein the mass concentration of ethanol in the aqueous ethanol solution is preferably 60-85%. After a large number of experiments, the inventor used a hydrolysis agent, especially an aqueous solution of ethanol, and controlled the water content in the hydrolysis agent, which can significantly reduce the content of impurities in the acesulfame precursor ASH, and reduce the difficulty of subsequent acesulfame potassium purification. The cost of acesulfame purification is reduced.

For the consumption of hydrolyzing agent, the application is not limited, the consumption of hydrolyzing agent can be determined according to the consumption of sulfur trioxide, specifically, in some embodiments of the application, the consumption of sulfur trioxide and the content of water in the hydrolyzing agent The ratio of the amount of substances is 1:1-4, in some other embodiments, it is 1:1-1.5. That is to say, the amount of water in the hydrolyzing agent is preferably higher than that of sulfur trioxide.

In some embodiments of the present application, there is no limit to the conditions of the hydrolysis reaction, and any requirement for the hydrolysis reaction can be met; in some embodiments of the present application, reference may be made to the prior art; in other embodiments of the present application, In the hydrolysis step, the reaction temperature of the hydrolysis reaction is -40°C to 0°C, preferably -20°C to 0°C. That is to say, the hydrolysis reaction step of the present application is preferably carried out at a lower temperature. In the present application, any one of the prior art can be used for temperature control, such as air condensation technology, circulating water condensation technology and heat exchange plate Wait. After repeated tests, it was found that -40°C to 0°C is the most suitable temperature for the hydrolysis reaction. If the reaction temperature is lower than -40°C, the hydrolysis may be incomplete, which will result in incomplete hydrolysis, and some cyclization products cannot be converted. The conversion rate of raw materials is low; if the reaction temperature is higher than 0°C, the reaction temperature is too high, and the cyclization product is easy to decompose, which is not conducive to the development of the reaction towards the hydrolysis reaction.

The preparation method of acetoacetamide-N-sulfonic acid triethylamine salt solution

The application does not limit the source of the acetoacetamide-N-sulfonic acid triethylamine salt solution, and can refer to the prior art, and can also be prepared by the following method:

The preparation of acetoacetamide-N-sulfonic acid triethylamine salt solution can be more carefully divided into two small steps. First, it is the preparation of ammonium sulfamate, and then the intermediate is prepared by reacting ammonium sulfamate with diketene , That is, acetoacetamide-N-sulfonic acid triethylamine salt.

The ammonium salt of sulfamic acid is obtained by adding triethylamine to the sulfamic acid solution for amination reaction. Specifically, in some embodiments of the present application, sulfamic acid is dissolved in the first solvent to configure the first reaction solution; triethylamine is dissolved in the second solvent to configure the second reaction solution, and the second The reaction solution is added to the first reaction solution to carry out amination reaction to form a sulfamic acid ammonium salt solution. The first solvent and the second solvent are inert organic solvents that can provide a reaction environment for the amination reaction, such as dichloromethane. Sulfamic acid and triethylamine react exothermicly. During the reaction, the heat generated will vaporize part of the dichloromethane, and the vaporized dichloromethane will leave the reaction system to take away the heat produced. Further, the vaporized dichloromethane Methane can also be recycled.

When the first reaction solution is mixed with the second reaction solution, it is best to gradually drop the second reaction solution into the first reaction solution, which can make the reaction more complete without causing excessive concentration of local reactants and excessive reaction .

A kind of specific implementation of generating sulfamic acid ammonium salt solution is given below, and this embodiment is only used as an illustration, and the specific production process of sulfamic acid ammonium salt solution can adopt any one in the prior art. Accurately weigh according to the consumption ratio of preset sulfamic acid, the first dichloromethane, triethylamine and the second dichloromethane, open the metering tank valve of the reactivity and add the first dichloromethane in the dry reaction kettle, Start the stirring and circulating pump; put in sulfamic acid from the feeding hole. Close the circulation valve, open the feeding valve, send the mixed material in the melting tank to a dry synthesis tank, use circulating water to cool down, and wait for the temperature of the reactor to drop to room temperature (about 20-25° C.) to obtain the first reaction liquid.

With the above process, obtain the second reaction solution in which triethylamine is dissolved in dichloromethane.

The second reaction solution was added dropwise to the first reaction solution. When the dropwise addition was completed, the pH value was 7-9, and the reaction was left to stand for 1 hour. The material after the above reaction was an ammonium sulfamate solution.

After obtaining the sulfamic acid solution, react the sulfamic acid solution with diketene to obtain acetoacetamide-N-sulfonic acid triethylamine salt as an intermediate for preparing acesulfame potassium.

In the prior art, the reaction between sulfamic acid solution and diketene is carried out in the environment of acetic acid. In the subsequent steps, acetic acid is difficult to be completely removed from the final product acesulfame potassium, and the acetic acid remaining in acesulfame potassium will not only The color of acesulfame potassium is not good, and it will also bring peculiar smell.

In this application, this problem is effectively overcome by adopting solid acidic catalyst instead of traditional acetic acid. Solid-state acidic catalysis can provide sufficient acidic sites for the acylation reaction. On the one hand, it can effectively catalyze the acylation reaction of ammonium sulfamate and diketene. On the other hand, solid-state acidic catalysis will not mix into the reaction product. , no special treatment process is required in the follow-up, which saves the post-treatment economy and time cost; and avoids the adverse effect on the product phase of the final product caused by the acetic acid impurities that are not removed in the prior art remaining in the final product.

In order to increase the flash point of diketene, diketene is dissolved in a third solvent to prepare a third reaction solution. The third solvent is an inert organic solvent that can provide a reaction environment for the amination reaction, such as dichloromethane. Fill the reactor with a solid acidic catalyst, add the ammonium sulfamate solution and the third reaction solution to the reactor in sequence, and react under preset conditions to form acetoacetamide-N-sulfonic acid triethylamine salt solution as an intermediate solution.

In order to realize the continuity of the reaction, in some embodiments of the present application, a continuous reactor can be selected to realize the present application, such as a fixed bed reactor, a continuous stirred tank reactor or a microchannel reactor, etc. Here, the fixed bed reactor is taken as an example to briefly explain the reaction process.

Fill the fixed bed reactor with solid acid catalyst as the catalyst, set the fixed bed reactor to the preset working state, first pass the ammonium sulfamate solution into the fixed bed reactor, and wait for the ammonium sulfamate solution to flow normally Afterwards, the third reaction solution is fed in the same direction, and by controlling the flow rate of the two, the contact time of the two is within the preset condition. At the same time, by controlling the heat exchange device of the fixed bed reactor, the reaction temperature is also in the preset condition. Within the set conditions, the reaction can be ended after the preset reaction time is reached, and the product acetoacetamide-N-sulfonic acid triethylamine salt solution is obtained. Due to the characteristics of the fixed bed reactor, the reaction can be carried out continuously and is suitable for large-scale industrial production.

The type and amount of solid acid catalyst

Some of the solid acid catalysts in this application are molecular sieve catalysts or solid superacid catalysts. Wherein, the molecular sieve catalyst is HZSM-5 molecular sieve and/or Na-ZSM-5 molecular sieve; the solid superacid catalyst is SO ₄ ²⁻ /Fe ₂ O ₃ type catalyst.

The application does not limit the amount of solid acid catalyst, which can be determined according to the type and specification of the reactor selected.

For the consumption and reaction conditions of above-mentioned other unmentioned reaction materials, all can refer to prior art, as in Chinese patent document CN112142687A, the molar ratio n (aminosulfonic acid) of sulfamic acid and diketene: n (diketene): n(triethylamine)=1:1.0-3.0:1.0-4.0; the acylation reaction temperature is -40 to 15°C; the dropping time is 10min-300min; the reaction time is 1-15h, etc.

Preparation of acetoacetamide-N-sulfonic acid triethylamine salt solution:

Amination reaction steps: Dissolve 98kg of sulfamic acid and the first dichloromethane at a molar ratio of 1:6, and control the dissolution temperature at about 20 to 25°C to obtain a dichloromethane solution of sulfamic acid, that is, the first The reaction solution. Dissolution can be in a continuous mixing device or in a reactor.

Dissolving triethylamine and second dichloromethane at a molar ratio of 1:1, controlling the dissolution temperature to be 10 to 30°C, to obtain a second reaction liquid, wherein the mass ratio of sulfamic acid to triethylamine is 1:1.2. Gradually add the second reaction solution dropwise into the reaction kettle where the first reaction solution is located, mix and stir, control the temperature of the system at 20 to 30°C, and control the system to be weakly alkaline, after mixing evenly, the ammonium sulfamate is obtained solution.

Acylation reaction step: dissolving diketene and third dichloromethane at a molar ratio of 1:1.5, controlling the dissolution temperature at 10 to 20° C. to obtain a third reaction solution.

After the solid superacid catalyst is installed in the fixed bed reactor, the fixed bed reactor is started, and the circulating water is adjusted to make the circulating water work normally.

Pass the sulfamic acid ammonium salt solution into the fixed-bed reactor, and after the sulfamic acid ammonium salt solution flows normally, pass the third reaction solution and the sulfamic acid ammonium salt solution into the fixed-bed reactor in the same direction to control amino The amounts of the ammonium sulfonate salt solution and the third reaction solution are such that the molar ratio of sulfamic acid to diketene is 1:1.1. After the reaction starts, lower the temperature of the cooling water as much as possible, and control the temperature of the reaction system at 20 to 35°C; as the performance of the catalyst declines, the temperature can be slightly increased within the control range.

Control the flow rate of ammonium sulfamate solution and diketene so that the reaction time is controlled at about 100 seconds. The target product acetoacetamide-N-sulfonic acid triethylamine salt solution was obtained.

In this application, the acetoacetamide-N-sulfonic acid triethylamine salt solution of each embodiment and comparative example is prepared by the above-mentioned method unless otherwise specified, and follow the special instruction if there is any special instruction.

Embodiment 1 to Embodiment 5

Sulfonated cyclization step: use acetoacetamide-N-sulfonic acid triethylamine salt solution as working fluid, dissolve sulfur trioxide in solvent to form cyclizing agent solution as injection fluid; working fluid from Venturi reactor The nozzle enters, and the injection fluid enters from the suction chamber of the Venturi reactor. In each embodiment, please refer to Table 1 for the pressure of the working fluid and the pressure of the injection fluid; make the working fluid and the injection fluid in the Venturi reactor The mixing section and the diffuser section are mixed to carry out the sulfonation ring closure reaction, and the sulfonation ring closure product is sprayed into the flow reactor.

Hydrolysis step: the sulfonated cyclization product is subjected to a hydrolysis reaction with an aqueous ethanol solution preset in a flow reactor to obtain a hydrolyzate solution; and

Salt-forming step: adding potassium hydroxide to the organic phase of the hydrolyzate solution to carry out a salt-forming reaction to obtain acesulfame potassium.

Except the reaction conditions enumerated in Table 1, the reaction conditions of each embodiment of other steps are all consistent.

Table 1:

Note: The yield of acesulfame potassium is the ratio of the actual yield of acesulfame potassium to the theoretical yield calculated with diketene.

Example 6

Sulfonated cyclization step: use acetoacetamide-N-sulfonic acid triethylamine salt solution as working fluid, dissolve sulfur trioxide in solvent to form cyclizing agent solution as injection fluid; working fluid from Venturi reactor The nozzle enters, and the injection fluid enters from the suction chamber of the Venturi reactor. In each embodiment, the pressure of the working fluid is 0.8MPa, the pressure of the injection fluid is 0.4MPa, the reaction temperature is -10 ° C, and the reaction time is 3 second; the working fluid and the injection fluid are mixed in the mixing section and the diffuser section of the Venturi reactor to carry out the sulfonation ring closure reaction, and the sulfonation ring closure product is sprayed into the flow reactor.

Hydrolysis step: the sulfonated cyclization product is hydrolyzed with ethanol aqueous solutions of different mass fractions preset in the flow reactor to obtain a hydrolyzate solution; for the specific mass fraction of ethanol, please refer to Table 2, and the hydrolysis reaction temperature is controlled at - 15～0℃.

Wherein, the organic impurity in Table 2 is the organic impurity content of the acesulfame potassium obtained above after one time of impurity removal.

Table 2:

As can be seen from Example 1, in implementing comparative example 1D and implementing comparative example 1E, the pressure of working fluid and injection fluid is the same, in this case, the yield of acesulfame potassium is compared with embodiment 1A, Embodiment 1B and embodiment 1C are relatively low, can only reach 59%～66%; The difference of embodiment 1A, embodiment 1B and implementing comparative example 1D and implementing comparative example 1E is that the pressure of working fluid is greater than the injection fluid The pressure, and the yield of acesulfame potassium has been significantly improved, reaching 89% to 91%.

As can be seen from Examples 1 to 5, the factors affecting the yield of acesulfame potassium except pressure control mainly include the sulfonation ring closure reaction time and reaction temperature. 1. Under the reaction conditions of the reaction time of 1-10s, the yield of acesulfame potassium can achieve a more ideal effect.

In Example 6, the ethanol aqueous solution of different mass fractions was used to hydrolyze the sulfonated cyclization product, and the subsequent salt-forming reaction was carried out. As can be seen from Table 2, the ethanol content in the ethanol aqueous solution is between 60% and 85% %, the amount of organic impurities in the final product acesulfame potassium has reached below 10ppm.

The above description is only a specific implementation manner of the present application, and those skilled in the art can make other improvements or modifications on the basis of the above embodiments under the above teaching of the present application. Those skilled in the art should understand that the above specific description is only to better explain the purpose of the present application, and the protection scope of the present application should be based on the protection scope of the claims.

In addition, those skilled in the art will appreciate that although some embodiments described herein include some features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the present application. and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.

Claims

A kind of preparation method of acesulfame potassium, it is characterized in that, described method adopts joint reactor to implement, and described joint reactor comprises Venturi reactor and flow reactor, the outlet of the diffuser section of described Venturi reactor Connected to the inlet of the flow reactor; the method comprises:

Sulfonated cyclization step: acetoacetamide-N-sulfonic acid triethylamine salt solution is used as the working fluid, sulfur trioxide is dissolved in the solvent to form a cyclizing agent solution as the injection fluid; the working fluid is extracted from the Venturi The nozzle of the reactor enters, and the ejection fluid enters from the suction chamber of the Venturi reactor, and the pressure of the working fluid is controlled to be higher than the pressure of the ejection fluid; the working fluid and the ejection fluid are Mixing in the mixing section and the diffuser section of the Venturi reactor to carry out the sulfonation ring closure reaction, and spraying the sulfonation ring closure product into the flow reactor;

Hydrolysis step: the sulfonated cyclization product undergoes a hydrolysis reaction with a hydrolysis agent preset in the flow reactor to obtain a hydrolyzate solution; and

Salt forming step: adding potassium hydroxide to the organic phase of the hydrolyzate solution to obtain acesulfame potassium.
The method according to claim 1, characterized in that, the pressure of the working fluid is 0.4-1.6 MPa, the pressure of the injection fluid is 0.2-1.4 MPa, and the pressure of the working fluid is higher than that of the injection fluid. The pressure of the fluid is 0.2-0.4MPa higher.
The method according to claim 1, characterized in that, in the sulfonation and cyclization step, spraying the sulfonation and cyclization product into the flow reactor comprises:

The sulfonated cyclization product is sprayed from the outlet of the diffuser section of the Venturi reactor at a pressure of 0.5-1.1 MPa, and sprayed into the flow reactor.
The method according to claim 1, characterized in that, in the step of sulfonation and cyclization, the temperature of the working fluid and the injection fluid is maintained at -35°C to 0°C, preferably -15°C to 0°C.
The method according to claim 1, characterized in that, in the hydrolysis step, the reaction temperature of the hydrolysis reaction is -40°C to 0°C, preferably -20°C to 0°C.
The method according to claim 1, characterized in that the hydrolysis agent is an aqueous ethanol solution, wherein the mass fraction of ethanol in the aqueous ethanol solution is 60-85%.
The method according to claim 1, characterized in that, the ratio of the molar mass of the sulfur trioxide to the molar mass of water in the hydrolyzing agent is 1:1-1.5.
method according to claim 1, is characterized in that, described acetoacetamide-N-sulfonic acid triethylamine salt solution is made by following method:

Add triethylamine in the sulfamic acid solution, carry out amination reaction, generate sulfamic acid ammonium salt solution; add diketene to the obtained sulfamic acid ammonium salt solution, under the action of solid acidic catalyst, carry out acylation reaction, obtain Acetoacetamide-N-sulfonic acid triethylamine salt solution.
The method according to claim 8, characterized in that, the solid-state acidic catalyst is a molecular sieve catalyst or a solid-state superacid catalyst.
The method according to claim 9, characterized in that, the molecular sieve catalyst is HZSM-5 molecular sieve and/or Na-ZSM-5 molecular sieve; the solid superacid catalyst is SO 4 2- /Fe 2 O 3 type catalyst .