WO2023123406A1

WO2023123406A1 - Method for preparing acesulfame potassium

Info

Publication number: WO2023123406A1
Application number: PCT/CN2021/143816
Authority: WO
Inventors: 陈永旭; 周睿; 王从春; 刘刚
Original assignee: 安徽金禾实业股份有限公司
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2023-07-06
Also published as: CN116322984A

Abstract

Disclosed in the present application is a method for preparing acesulfame potassium. The method comprises the following steps: step 1, mixing sulfamic acid and an amine for reaction to prepare amino sulfamate; step 2, reacting the amino sulfamate with diketene to obtain a first material; step 3, reacting the first material with a sulfur trioxide solution to obtain a second material; step 4, reacting the second material with a hydrolysate to obtain a third material; and step 5, reacting an organic phase separated from the third material with a potassium-containing compound to prepare acesulfame potassium, wherein amino acetyl acetyl-N-sulfamate in the first material in step 3 continuously reacts with sulfur trioxide in a constant molar ratio. The present application has the advantage of continuous reaction.

Description

A kind of method for preparing acesulfame potassium

technical field

The invention relates to the field of chemical industry, in particular to a method for preparing acesulfame potassium.

Background technique

Acesulfame potassium, namely AK sugar (Acesulfame-K), the chemical name is 6-methyl-1,2,3-oxathiazin-4(3H)-one-2,2-potassium dioxide (6-Methyl -1,2,3-oxathiazin-4(3H)-one 2,2-dioxide potassium salt), commonly known as acesulfame potassium; appearance is colorless crystal; easily soluble in water, the solubility is 270g/L at 20℃; CAS No.: 55589-62-3; molecular weight: 201.24; melting point (°C): 229-232; relative density (water = 1): 1.81; pH: pH = 5.5-7.5.

Acesulfame K has the advantages of safety, non-toxicity, stable properties, refreshing sweetness, no bad aftertaste, and reasonable price. It is widely used as a sweetener in food and medicine.

At present, the sulfamic acid-sulfur trioxide method is the mainstream process for the production of acesulfame potassium due to the easy availability of raw materials, mild reaction conditions, high product yield and high purity. The research on acesulfame potassium is gradually in-depth along with the development.

In the prior art, CN113454075A pays attention to the acidity and alkalinity of the cyclization reaction; CN111377882A proposes a microreactor for rapid reaction; CN113508110A proposes to perform reaction under pressure mixing in the reactor.

However, sulfur trioxide needs to be dissolved in a solvent as a cyclizing agent. Considering various reasons in current production practice, dichloromethane is the preferred solvent. Dichloromethane has a relatively excellent effect. However, after sulfur trioxide is dissolved in methylene chloride, due to the exothermic reaction during the cyclization reaction, generally speaking, it is reacted at a low temperature (-30 to 0°C), and it is always desired to reduce side reactions during the reaction. In order to reduce the occurrence of impurities, and minimize the decomposition of products.

Contents of the invention

The inventors have found that the sulfur trioxide cyclizing agent used in the prior art has a high viscosity, and the microchannel reaction has the problems of being easily blocked and requiring a large load of pressure; using an ordinary reactor for reaction has a long reaction time , more side reactions, serious product decomposition, and the consequences are reduced yield and increased impurities, which are very unfavorable. In addition, due to the above problems, the cyclization reaction usually uses a reactor reaction, which makes the reaction unable to be carried out continuously. If it cannot be carried out continuously, the automatic control capability of the reaction equipment will be reduced.

The object of the present invention is to provide a kind of method for preparing acesulfame potassium.

In order to achieve the above purpose and other related purposes, the present invention adopts the following technical solutions:

A method for preparing acesulfame potassium, comprising the steps of:

Step 1: mixing and reacting sulfamic acid and amine to prepare amine salt of sulfamic acid;

Step 2: reacting sulfamic acid amine salt with diketene to obtain the first material;

Step 3: reacting the first material with sulfur trioxide solution to obtain the second material;

Step 4: reacting the second material with the hydrolyzate to obtain the third material;

Step 5: reacting the organic phase separated from the third material with a potassium-containing compound to obtain acesulfame potassium;

In step 3, the acetoacetyl-N-sulfamic acid amine salt and sulfur trioxide in the first material are continuously reacted at a constant material ratio.

Wherein the sulfur trioxide solution is an inert organic solvent solution of sulfur trioxide.

Wherein the sulfur trioxide solution is a dichloromethane solution of sulfur trioxide.

Wherein the amine in step 1 is triethylamine.

Wherein the mass fraction of acetoacetyl-N-sulfamate in the first material is greater than 35%.

In step 4, the first material and the sulfur trioxide solution are fed into the ring-closure reaction device at a constant ratio.

Wherein, both the first material and the sulfur trioxide solution are sprayed to the reaction position using a spraying device.

Wherein the reaction position is an inclined plane, and the inclined plane is connected with the reactor.

Wherein in step 3, the second material overflows out of the reactor.

It also includes a first material injection device electrically connected to the controller, a sulfur trioxide solution injection device, a first container of sulfur trioxide solution, and a second container of sulfur trioxide solution.

It also includes a one-way valve; wherein the controller controls the opening and flow of the first material injection device and the sulfur trioxide solution injection device according to the artificial setting value; the controller compares the material level of the first container of the sulfur trioxide solution with the setting value. The difference between them is controlled to open the one-way valve between the first container of sulfur trioxide solution and the second container of sulfur trioxide solution.

Wherein the pressure of the first container of the sulfur trioxide solution is greater than the pressure of the second container of the sulfur trioxide solution.

The present invention can be carried out continuously. The material containing the intermediate DKA and the sulfur trioxide solution are sprayed onto the slope in a fixed ratio by spraying. The sprayed material mixes conveniently and evenly, and then flows into the reaction tank. After the reaction is completed, Overflow through the other end of the reaction tank, and then export. In this way, the volume of the reaction tank is small, the control is simple, the reaction is continuous, the requirements for the refrigeration capacity and volume of the equipment are low, and the cost of the equipment is reduced. The storage and use of sulfur trioxide is safe.

Description of drawings

Fig. 1 is the front view of one-sided slope overflow reaction tank;

Fig. 2 is the right view of Fig. 1;

Fig. 3 is a schematic diagram of the control of the sulfur trioxide solution injection equipment.

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the process equipment or devices not specifically indicated in the following examples all adopt conventional equipment or devices in the art. In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude that there may be other method steps before and after the combined steps or other method steps may be inserted between these explicitly mentioned steps, unless otherwise There are instructions; it should also be understood that the combined connection relationship between one or more devices/devices mentioned in the present invention does not exclude that there may be other devices/devices before and after the combined device/devices or those explicitly mentioned Other devices/apparatus can also be interposed between the two devices/apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the sequence of each method step or limit the scope of the present invention. The change or adjustment of its relative relationship is in In the case of no substantive change in the technical content, it shall also be regarded as the applicable scope of the present invention.

A method for preparing acesulfame potassium, comprising the following steps: Step 1: reacting sulfamic acid and amine to prepare sulfamic acid amine salt; reacting sulfamic acid with amine to form sulfamic acid salt, common The uses triethylamine as the amine and produces triethylammonium sulfamate. The amine may also be selected from trimethylamine, tri-n-butylamine, triisobutylamine, triisopropylamine and mixtures thereof. Acetic acid is also generally added to the sulfamic acid and amine to initiate and effectively maintain the reaction, since the reaction is usually carried out with an excess of amine, the addition of acetic acid acts to catalyze and neutralize the amine.

Step 2: reacting sulfamic acid amine salt with diketene to obtain the first material; reacting sulfamic acid amine salt with acetylacetylating agent to form acetoacesulfame triethylamine salt, preferably acetoacetamide-N - triethylammonium sulfonate. Acetoacetylating agents include diketene. Taking the formation of acetoacetamide triethylammonium salt as an example, acetoacetamide-N-sulfonic acid triethylammonium salt and diketene are used as reactants and produce acetoacetamide triethylammonium salt. An organic solvent can be used for the formation reaction of ammonium sulfamate and the formation reaction of acesulfame triethylamine salt, and the organic solvent is preferably dichloromethane, chloroform, trichloroethylene, acetone, glacial acetic acid and mixtures thereof. As shown in the following formula, acesulfame triethylamine salt has isomers. These two isomers can be converted into each other. This conversion affects the increase in yield and reaction time.

Step 3: reacting the first material with sulfur trioxide solution to prepare the second material; this step is a ring-closing step. Acesulfametotriethylamine salt is reacted with a cyclizing agent in the presence of a solvent to form a cyclic sulfur trioxide adduct composition. Sulfur trioxide adducts may contain multiple sulfur trioxides. Preferred solvents for the cyclization reaction are dichloromethane, acetone, glacial acetic acid, trichloroethylene and mixtures thereof.

Step 4: reacting the second material with the hydrolyzate to obtain the third material; that is, the hydrolysis step. The cyclic sulfur trioxide adduct can be hydrolyzed to form acesulfame (ACH) via conventional means such as addition of water or other aqueous solution. After hydrolysis, water is used as a solvent to dissolve sulfuric acid, and the target product ACH is mostly dissolved in the organic phase.

Step 5: reacting the organic phase in the third material with a potassium-containing compound to obtain acesulfame potassium; that is, the neutralization step. Neutralization of ACH with base yields a crude acesulfame potassium composition comprising acesulfame potassium and some impurities.

The key content of the present invention lies in step 3, wherein the first material, that is, the mixture containing acetoacetyl-N-sulfanilic acid triethylamine (DKA) and sulfur trioxide are continuously reacted with a constant material ratio.

In the prior art, after the first material is obtained, the first material is put into the reactor, then the temperature of the reactor is lowered to -30° C., and then the sulfur trioxide solution is added dropwise. Sulfur trioxide reacts with DKA to produce sulfur trioxide adducts. This reaction process is violent and exothermic. Generally speaking, continuous cooling is required to maintain the low temperature, and the reaction needs to be maintained for a period of time depending on the rate of sulfur trioxide addition.

In view of this situation, the inventor proposed a new method to change the ring closure reaction: spray and mix the sulfur trioxide solution and the first material at the same time, react directly after mixing, and then flow out of the reactor. Due to the high viscosity of sulfur trioxide solution, it needs to be pressurized for injection. However, the overall pressurization has high requirements on the equipment and is not conducive to safety. Therefore, the inventor designed a sectioned pressurization method. After the sulfur trioxide injection, it is necessary to maintain a certain reaction time with the first material, so the inventor designed a single-side slope overflow reaction tank.

See Figure 1. The one-sided slope overflow reaction tank includes slope 1 and reaction tank 2. FIG. 2 is a right side view of FIG. 1 , wherein the overflow opening 3 can be seen. The sulfur trioxide solution and the first material are simultaneously sprayed onto the reaction position, that is, the one-sided inclined surface, and the areas of the spraying points overlap. In this way, the sulfur trioxide solution and the first material realize uniform liquid mixing, and after mixing, slowly flow into the overflow reaction tank along the one-side slope. The other side opposite to the inclined plane is an overflow port, and the height of the overflow port is lower than the side height of the reaction tank. The reaction liquid flows into the reaction tank from the side, and the mixed liquid that has reacted on one side of the overflow port overflows from the overflow port. In this way, a continuous reaction is realized. Multiple injectors can be used for spraying, and a Venturi injector can be selected for the injector. The impact area of the injector can be substantially elongated.

The purpose of setting the slope is to form a stable gradient reaction material in the reaction tank. After being sprayed on the slope, the spray liquid can flow down from the slope and flow into the reaction tank after being mixed. If it is sprayed directly to the reaction tank, it will cause the chaotic flow of the reaction liquid, which is not conducive to the complete progress of the reaction. The inclination angle of the slope relative to the reaction tank is 20-30°.

The flow of the reaction liquid in the reaction tank can be designed according to the overall capacity of the reaction tank. For example, if the injection volume per hour is 2000L, the overall capacity of the reaction tank can be selected as 2000L to realize the control of the reaction time. The gradient contour line of the reaction degree in the reaction tank is basically parallel to the overflow port, so the reaction can be completely carried out.

In order to control the injection of the sulfur trioxide solution, a controller is used in the present invention to control the sulfur trioxide solution. Referring to Fig. 3, wherein the second container 4 of sulfur trioxide solution is connected to the first container 5 of sulfur trioxide solution, and the first container 5 is connected to the sulfur trioxide solution injection device 6; The first container and the second container of sulfur trioxide solution are electrically connected with the controller 7 . A first material injection device (not shown) electrically connected to the controller is also included.

The sulfur trioxide solution first container can pressurize the sulfur trioxide solution stored, and can be ejected by the sulfur trioxide solution injection device 6 after pressurization. In order to reduce the energy consumption of the pressure device and improve safety, and prevent damage caused by a large amount of sulfur trioxide ejection, a check valve is set between the first container of sulfur trioxide solution and the second container of sulfur trioxide solution; The first container can receive the material delivery from the second container of sulfur trioxide solution, so that the first container of sulfur trioxide solution and the second container of sulfur trioxide solution can use different pressure control strategies. The controller controls the opening and flow of the first material injection device and the sulfur trioxide solution injection device according to the artificial setting value; the controller compares the material level of the first container of the sulfur trioxide solution with the calculated value according to the artificial setting value. Difference, for example, when the material level in the first container is maintained at 30%, or when 40%, control opens the one-way valve between the first container of sulfur trioxide solution and the second container of sulfur trioxide solution, to the sulfur trioxide solution. The solution first container is fed with sulfur trioxide solution. In this way, the pressure of the first container of the sulfur trioxide solution is greater than the pressure of the second container of the sulfur trioxide solution, preparing for injection of high-viscosity fluid at low temperature.

In the present invention, the sulfur trioxide solution is mixed with the first material in a fixed quantity, that is, the mixed reaction of DKA and the fixed quantity of sulfur trioxide is realized. This is very effective for reducing side reactions and increasing productivity.

Example 1

Dissolve 10,000 mol of sulfamic acid in about 35,000-42,000 mol of dichloromethane. When the reaction is over, check the pH value of the solution, which shows that the pH value is between 6.5-7. Then add 10500-10150 mol of triethylamine dropwise to the solution in the previous step, stirring while adding dropwise, and the dropwise adding time is about 4 hours. Then add glacial acetic acid dropwise to the solution in the previous step, the amount of glacial acetic acid is the reaction amount of the remainder of triethylamine, stir while adding dropwise, maintain the temperature at 15°C for 2 hours. Subsequently, 10500-10150 mol of diketene was added dropwise to the solution in the previous step, and the initial condition of the reaction was controlled to be 10°C. Stirring while adding was added dropwise for about 5 hours. During the dropwise addition, the temperature of the reaction solution was controlled to rise slightly. 25°C; then transfer it to a reaction kettle, gradually lower the temperature under control, and react for 60 minutes under temperature-controlled conditions, with a final temperature of 3-5°C. After the reaction is completed, quickly cool down to about 0°C and use it as a raw material for the cyclization reaction.

The amount of DKA in the reactant was detected, and the mass fraction of DKA was about 41.9%.

In the case of obtaining the first material above, the inventor dissolved 60,000 mol of sulfur trioxide in 120,000 mol of methylene chloride, mixed uniformly, and sprayed it with the above first material in a constant ratio to a single-sided slope overflow reaction tank. Control the temperature of the reaction tank to -30°C, select a suitable length, width and height of the reaction tank, control the reaction time of the reactants to 30-120 minutes, and the reactants flow out from the overflow port.

After the reaction is completed, the overflowing reactant is hydrolyzed, and the organic phase is extracted. ACH is dissolved in the organic phase. ACH is measured, and the mass fraction of ACH is about 7.4%.

Comparative example 1

In the case of obtaining the first material above, the inventor dissolved 60,000 mol of sulfur trioxide in 120,000 mol of dichloromethane, and after mixing evenly, added the solution of sulfur trioxide in dichloromethane dropwise into the first material. Maintain the reaction temperature at -30°C for 120-300 minutes.

After the reaction is completed, the reactant is hydrolyzed, and the organic phase is extracted. ACH is dissolved in the organic phase, and ACH is measured, and the mass fraction of ACH is about 5.1%.

In the embodiment of the present invention, the first material and the sulfur trioxide solution are added in equal proportions, so there is no excess material during the reaction process, which reduces the occurrence of side reactions. The reaction time of the reactants in the reaction tank is short, and the possibility of product decomposition is significantly reduced. These two factors are the main reason why the ACH content number is improved in the method of the present invention. The comparative example is a routinely used process, and the components in the solution are always changed during the reaction of this process, which affects the progress of the reaction.

From the perspective of the overall equipment cost, due to the continuous reaction, the reactor and cooling device are all made of miniaturized equipment, and the price is significantly reduced; in addition, after continuous operation, the number of on-site operators is reduced, and automatic control can be realized.

Due to the continuous operation, the equipment no longer needs two steps of discharging and feeding, and the overall utilization rate of the equipment has been improved. Continuous production can also be achieved using microchannels, but the volume of microchannel reactions is smaller. The invention makes the continuous production of the industrial production scale possible, reduces the production cost and improves the quality of the product.

The above examples are intended to illustrate the disclosed embodiments of the present invention, and should not be construed as limiting the present invention. In addition, various modifications set forth herein, as well as changes in the method and composition of the invention, will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been specifically described in connection with various specific preferred embodiments of the invention, it should be understood that the invention should not be limited to these specific embodiments. In fact, various modifications as mentioned above which are obvious to those skilled in the art to obtain the invention should be included in the scope of the present invention.

Claims

A method for preparing acesulfame potassium, comprising the steps of:

Step 1: mixing and reacting sulfamic acid and amine to prepare amine salt of sulfamic acid;

Step 2: reacting sulfamic acid amine salt with diketene to obtain the first material;

Step 3: reacting the first material with sulfur trioxide solution to obtain the second material;

Step 4: reacting the second material with the hydrolyzate to obtain the third material;

Step 5: reacting the organic phase separated from the third material with a potassium-containing compound to obtain acesulfame potassium;

It is characterized in that: in the step 3, the acetoacetyl-N-sulfamic acid amine salt in the first material and sulfur trioxide react continuously at a constant material ratio.
The method for preparing Acesulfame Potassium as claimed in claim 1, is characterized in that:

Wherein the sulfur trioxide solution is an inert organic solvent solution of sulfur trioxide.
The method for preparing Acesulfame Potassium as claimed in claim 1, is characterized in that:

Wherein the sulfur trioxide solution is a dichloromethane solution of sulfur trioxide.
The method for preparing Acesulfame Potassium as claimed in claim 1, is characterized in that:

Wherein the amine in step 1 is triethylamine.
The method for preparing Acesulfame Potassium as claimed in claim 1, is characterized in that:

Wherein the mass fraction of acetoacetyl-N-sulfamate in the first material is greater than 35%.
The method for preparing Acesulfame Potassium as claimed in claim 1, is characterized in that:

In step 4, the first material and the sulfur trioxide solution are fed into the ring-closure reaction device at a constant ratio.
The method for preparing Acesulfame Potassium as claimed in claim 1, is characterized in that:

Wherein, both the first material and the sulfur trioxide solution are sprayed to the reaction position using a spraying device.
The method for preparing Acesulfame Potassium as claimed in claim 7, is characterized in that:

Wherein the reaction position is an inclined plane, and the inclined plane is connected with the reactor.
The method for preparing Acesulfame Potassium as claimed in claim 1, is characterized in that:

Wherein in step 3, the second material overflows out of the reactor.
The method for preparing Acesulfame Potassium as claimed in claim 1, is characterized in that:

It also includes a first material injection device electrically connected to the controller, a sulfur trioxide solution injection device, a first container of sulfur trioxide solution, and a second container of sulfur trioxide solution.
The method for preparing acesulfame potassium as claimed in claim 10, is characterized in that:

It also includes a one-way valve; wherein the controller controls the opening and flow of the first material injection device and the sulfur trioxide solution injection device according to the artificial setting value; the controller compares the material level of the first container of the sulfur trioxide solution with the setting value. The difference between them is controlled to open the one-way valve between the first container of sulfur trioxide solution and the second container of sulfur trioxide solution.
The method for preparing acesulfame potassium as claimed in claim 10, is characterized in that:

Wherein the pressure of the first container of the sulfur trioxide solution is greater than the pressure of the second container of the sulfur trioxide solution.