Acesulfame potassium composition and producing method thereof

Abstract

To provide a method for producing purified acesulfame potassium.SOLUTION: A method for producing acesulfame potassium includes a step of preparing a crude acesulfame potassium composition containing acesulfame potassium and acetoacetamide; a step of concentrating the crude acesulfame potassium composition to form an intermediate acesulfame potassium composition containing a water flow and acesulfame potassium with less than 75 weight% water; and a step of separating the intermediate acesulfame potassium composition to form a purified acesulfame potassium composition containing acesulfame potassium and less than 33 wpppm of acetoacetamide. The weight% of acetoacetamide in the purified acesulfame potassium composition is lower than that in the crude acesulfame potassium composition, with the concentration step being conducted at a temperature below 85°C and the separation step being conducted at a temperature below 20°C.SELECTED DRAWING: None

Description

Technical Field

[0001]

[0001] This patent application is related to and claims priority to U.S. Provisional Patent Application No. 62 / 397,509, filed on September 21, 2016, the disclosure of which is incorporated herein by reference in its entirety.

[0002]

[0002] The present invention generally relates to acesulfame potassium and methods for manufacturing acesulfame potassium. More specifically, the present invention relates to a method for manufacturing high-purity acesulfame potassium.

Background Art

[0003]

[0003] Acesulfame potassium has a very strong sweetness and is used as a sweetener in many food-related applications. In conventional acesulfame potassium manufacturing processes, sulfamic acid is reacted with an amine, such as triethylamine, to form an amidosulfamate, such as trialkylammonium amidosulfamate. Next, the amidosulfamate is reacted with diketene to form an acetoacetamide salt. The acetoacetamide salt can be cyclized, hydrolyzed, and neutralized to form acesulfame potassium. Representative acesulfame potassium manufacturing processes are disclosed in U.S. Patents 5,744,010 and 9,024,016.

[0004]

[0004] Typically, the acetoacetamide salt intermediate is cyclized by reacting it with sulfur trioxide in an inorganic or organic solvent to form a cyclic sulfur trioxide adduct. The solvent commonly used in this reaction is an organic solvent such as a halogenated aliphatic hydrocarbon solvent, for example, dichloromethane. The adduct formed by this reaction is subsequently hydrolyzed and then neutralized with potassium hydroxide to form acesulfame potassium.

[0005]

[0005] Acesulfame potassium products and intermediate compositions produced by conventional methods contain undesirable impurities such as acetoacetamide (and acetoacetamide-N-sulfonic acid). Often, regulatory limits or customer guidelines set limits on the content of various impurities. It has been found difficult to remove many of these impurities using standard purification procedures such as evaporation, crystallization, and / or filtration, resulting in consumer dissatisfaction and non-compliance with standards.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0006]

PATENT DOCUMENT 1

PATENT DOCUMENT 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0007]

[0006] There is a need for an improved method for producing high-purity acesulfame potassium compositions that reduces or eliminates the formation of impurities such as acetoacetamide during synthesis.

[0008]

[0007] All references discussed herein are incorporated herein by reference.

MEANS FOR SOLVING THE PROBLEM

[0009]

[0008] This application is a method for producing a finished acesulfame potassium composition, comprising acesulfame potassium, acetoacetamide, composition), which A step of preparing a crude potassium acesulfame composition containing water; concentrating the crude potassium acesulfame composition to form an intermediate potassium acesulfame composition containing a water stream, potassium acesulfame, and less than 33 wppm of acetoacetamide (and optionally less than 33 wppm of acetoacetamide-N-sulfonic acid); and separating the intermediate potassium acesulfame composition to form a purified potassium acesulfame composition containing potassium acesulfame and less than 33 wppm of acetoacetamide; The above method is disclosed. The concentration step is carried out at a temperature lower than 90 °C, and the separation step is carried out at a temperature of 35 °C or lower. The weight percentage of acetoacetamide in the purified potassium acesulfame composition can be lower than the weight percentage of acetoacetamide in the crude potassium acesulfame composition. The intermediate potassium acesulfame composition may contain less than 33 wppm of acetoacetamide-N-sulfonic acid. Preparing the crude acesulfame composition includes reacting sulfamic acid with an amine to form an amidosulfamate; reacting the amidosulfamate with an acetoacetylating agent to form an acetoacetamide salt; reacting the acetoacetamide salt with a cyclizing agent in a cyclizing agent composition to form a cyclic sulfur trioxide adduct; hydrolyzing the cyclic sulfur trioxide adduct to form an acesulfame-H composition containing acesulfame-H; and neutralizing the acesulfame-H in the acesulfame-H composition to form a crude potassium acesulfame composition containing potassium acesulfame and acetoacetamide; can be included. The concentration step can include evaporating the crude potassium acesulfame composition to form an intermediate potassium acesulfame composition containing a water stream, potassium acesulfame, and less than 75% by weight of water; and the evaporation residence time may be less than 180 minutes. Separation can include crystallizing the intermediate potassium acesulfame composition to form potassium acesulfame crystals; and filtering the potassium acesulfame crystals to form a purified potassium acesulfame composition.Preferably, the concentration involves evaporating the crude potassium acesulfame composition to form an intermediate potassium acesulfame composition containing a water stream, as well as potassium acesulfame and less than 50% by weight of water, and the separation involves crystallizing the intermediate potassium acesulfame composition to form a crystal-containing stream containing potassium acesulfame crystals; and filtering the crystal-containing stream to form a purified potassium acesulfame composition. The filtration can be carried out at a temperature of 35 °C or lower, and / or the crystallization can be carried out at a temperature of 35 °C or lower, and / or at least two filtration operations can be included. In some cases, the evaporation can be carried out at a temperature lower than 85 °C, the intermediate potassium acesulfame composition can contain 1 wppb to 33 wppm of acetoacetamide (and optionally less than 33 wppm of acetoacetamide-N-sulfonic acid), and the purified potassium acesulfame composition can contain less than 33 wppm of acetoacetamide. In one embodiment, the evaporation can be carried out at a temperature lower than 60 °C, the residence time in the evaporator is less than 50 minutes, the intermediate potassium acesulfame composition can contain 10 wppb to 25 wppm of acetoacetamide (and optionally less than 30 wppm of acetoacetamide-N-sulfonic acid), and the purified potassium acesulfame composition can contain 10 wppb to 15 wppm of acetoacetamide. In one embodiment, the evaporation can be carried out at a temperature lower than 46 °C, the residence time in the evaporator can be less than 30 minutes, the crystallization can be carried out at a temperature lower than 35 °C, the intermediate potassium acesulfame composition can contain 10 wppb to 12 wppm of acetoacetamide (and optionally less than 20 wppm of acetoacetamide-N-sulfonic acid), and the purified potassium acesulfame composition can contain 10 wppb to 7 wppm of acetoacetamide.In some cases, evaporation is carried out at a temperature in the range of 20°C to 55°C; the evaporator residence time is in the range of 1 minute to 300 minutes; separation is carried out at a temperature in the range of -10°C to 15°C; the separation operation residence time is in the range of 1 to 180 minutes; the crude potassium acetosulfamate composition contains 500 wppm to 2375 wppm of acetoacetamide; the intermediate potassium acetosulfamate composition contains 10 wppb to 20 wppm of acetoacetamide, and 10 wppb to 20 wppm of acetoacetamide-N-sulfonic acid; the purified potassium acetosulfamate composition contains 10 wppb to 10 wppm of acetoacetamide, and 1 wpp. It contains 20 wppm or less of acetoacetamide-N-sulfonic acid. Crystallization can be carried out at a pH lower than 10. The crude acesulfame composition may further contain a solvent, and this method can further include removing the solvent from the crude acesulfame potassium composition before evaporation. This method can include separating a transition phase containing at least 2% by weight of acetoacetamide from the acesulfame-H composition to form a purified acesulfame-H composition; the neutralization can include neutralizing acesulfame-H in the purified acesulfame-H composition to form a crude acesulfame potassium composition containing acesulfame potassium and acetoacetamide. In one embodiment, this method includes reacting sulfamic acid with triethylamine to form an amidosulfamic acid salt; reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt; contacting dichloromethane with sulfur trioxide to form a cyclizing agent composition; reacting the acetoacetamide salt with sulfur trioxide in the cyclizing agent composition to form a cyclic sulfur trioxide adduct; hydrolyzing the cyclic sulfur trioxide adduct to form an acesulfame-H composition; neutralizing acesulfame-H to form a crude acesulfame potassium composition containing acesulfame potassium and acetoacetamide; evaporating the crude acesulfame potassium composition to form an intermediate acesulfame potassium composition containing a water stream and less than 75% by weight of water and acesulfame potassium; crystallizing the intermediate acesulfame potassium composition to form acesulfame potassium crystals; and filtering the acesulfame potassium crystals to form a purified acesulfame potassium composition containing acesulfame potassium and less than 10 wppm of acetoacetamide. Evaporation can be carried out at a temperature lower than 50°C, the evaporator residence time can be less than 30 minutes, filtration can be carried out at a temperature lower than 35°C, and / or crystallization can be carried out at a temperature lower than 35°C. This application also describes the crude, intermediate, and purified compositions of acesulfame potassium produced by the methods described herein.In some cases, the present application describes an acetamiprid potassium composition that contains acetamiprid potassium and less than 33 wppm, preferably less than 10 wppm, of acetoacetamide, and optionally further contains less than 33 wppm, preferably less than 10 wppm, of acetoacetamide-N-sulfonic acid. In some cases, the acetamiprid potassium composition further contains 0.001 wppm to 5 wppm of organic impurities and / or 0.001 wppm to 5 wppm of at least one heavy metal (for example, at least one heavy metal is selected from the group consisting of mercury, lead, and mixtures thereof). In some cases, the acetamiprid potassium composition further contains mercury present in an amount of 1 wppb to 20 wppm and / or lead present in an amount of 1 wppb to 25 wppm.

[0010]

[0009] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0011]

Figure 1

[0010] FIG. 1 is a process flow sheet of an acetamiprid potassium manufacturing process according to one aspect of the present invention.

Figure 2

[0011] FIG. 2 is a process flow sheet of an acetamiprid potassium manufacturing process using one aspect of the treatment scheme of the present invention.

Modes for Carrying Out the Invention

[0012] Introduction :

[0012] Conventional processes for manufacturing potassium acesulfame involve reacting sulfamic acid and an amine in the presence of acetic acid to form an amidosulfamate. Next, the amidosulfamate is reacted with an acetoacetylating agent, such as diketene, to form an acetoacetamide salt. The acetoacetamide salt is reacted with a cyclizing agent, such as sulfur trioxide, to form a cyclic sulfur trioxide adduct. Next, the cyclic sulfur trioxide adduct is hydrolyzed and neutralized by conventional means to form a crude potassium acesulfame composition containing potassium acesulfame. This composition is phase-separated into an aqueous phase and an organic phase. Most of the potassium acesulfame is separated into the aqueous phase. As used herein, the term "crude potassium acesulfame composition" refers to the first product of the neutralization reaction or the aqueous phase formed from the phase separation step (without further purification). The crude potassium acesulfame composition contains at least 5% by weight of potassium acesulfame. In some cases, the crude potassium acesulfame composition can be treated to form the "intermediate potassium acesulfame composition" and / or the "purified potassium acesulfame composition" discussed below.

[0013]

[0013] Conventional potassium acesulfame compositions have been shown to contain several undesirable impurities, among others, acetoacetamide, and acetoacetamide salts, such as acetoacetamide-N-sulfonate triethylammonium salt. Acetoacetamide-N-sulfonic acid and its salts may also be present. The content limits for these compounds in the purified potassium acesulfame composition are often determined by industry purity standards and / or standards defined for specific end products using potassium acesulfame as a sweetener. In some cases, the limits for these impurities are determined by government regulations. For most applications, a high potassium acesulfame purity level is preferred. Thus, the crude potassium acesulfame composition is usually treated by various processing operations to reduce the abundance of these impurities. A non-limiting list of such processing operations includes evaporation, crystallization, and / or filtration.

[0014] Although not bound by theory, it has been found that these processing operations can generate stress on the acesulfame potassium molecule, such as heat stress. This heat stress can also be formed during the hydrolysis step and may affect acesulfame-H, which is a precursor to acesulfame potassium and is also known as sweetener acid. This stress on acesulfame potassium and possibly acesulfame-H can cause the decomposition of these compounds, leading to the formation of undesirable impurities. In some situations, this stress can cause acesulfame potassium / acesulfame-H to decompose into its formation reaction reactants, such as acetoacetamide and / or its salts and / or acetoacetamide-N-sulfonic acid, which may cause the formation of further impurities.

[0015] Also, it has been discovered here that by using specific processing parameters, the stress on acesulfame potassium (or acesulfame-H) can be advantageously reduced or eliminated, and / or the decomposition of the product can be advantageously reduced or eliminated, thereby reducing or eliminating the formation of further impurities and ultimately resulting in a high-purity final product.

[0016] In particular, it has been found that by carrying out the treatment (or individual treatment steps) within a specific temperature range or limit and / or by maintaining the treatment residence time within a specific time range or limit, the decomposition of acetosulfame potassium (or acetosulfame-H) and the formation of impurities (examples of which include the (re)formation of acetoacetamide and its salts) are surprisingly reduced or eliminated. Traditionally, treatment operations, such as evaporation, have been carried out at higher temperatures in order to improve the process rate and to rapidly remove water. By reducing the decomposition of acetosulfame potassium and acetosulfame-H, the formation of a higher purity crude acetosulfame potassium composition as discussed herein is directly led to, thereby simplifying the subsequent treatment operations for forming an intermediate composition or a purified composition of acetosulfame potassium. Also, this process advantageously results in the formation of intermediate compositions and purified compositions of acetosulfame potassium having a low content of acetoacetamide-N-sulfamic acid and / or acetoacetamide.

[0017] Here, further specific terms used herein are defined.

[0018] As used herein, "acetoacetamide-N-sulfonic acid" refers to the molecule shown below. In some cases, acetoacetamide-N-sulfonic acid may be a decomposition product of acetosulfame potassium or acetosulfame-H. The term "acetoacetamide-N-sulfonic acid" as used herein also includes salts of acetoacetamide-N-sulfamic acid, such as potassium salts, sodium salts, and other alkali metal salts.

[0018]

Chemical formula

[0019] As used herein, "acetoacetamide" refers to the following molecule.

[0020]

Chemical formula

[0021]

[0020] The crude asulam composition can be processed to form an intermediate asulam potassium composition and a purified asulam composition, and this processing step can include one or more concentration or separation operations.

[0022]

[0021] The "intermediate asulam potassium composition" refers to a composition obtained by concentrating the crude asulam potassium composition, for example, by removing water from the crude asulam potassium composition. This intermediate asulam potassium composition contains at least 10% by weight of asulam potassium based on the total weight of the intermediate asulam potassium composition, and has a higher weight percentage of asulam potassium than that of the crude asulam potassium composition.

[0023]

[0022] The "purified asulam potassium composition" refers to a composition obtained (preferably directly) by separating the intermediate asulam potassium composition, for example, by crystallization and / or filtration. The purified asulam potassium composition contains at least 15% by weight of asulam potassium based on the total weight percentage of the purified asulam potassium composition, and has a higher weight percentage of asulam potassium than that of the intermediate asulam potassium composition.

[0024]

[0023] As used herein, the "residence time" refers to the time for which a composition (or stream) to be processed, such as a crude asulam potassium composition, is held during a specific processing operation. The residence time starts when the composition to be processed is introduced into the processing operation, and the residence time is (by the treatment It ends when the resulting composition is discharged from the processing operation. As one specific example, the residence time for a concentration operation, such as evaporation, refers to the time from when the crude acetosulfame potassium composition is introduced into the evaporator until the intermediate acetosulfame potassium composition is discharged from the evaporator. As another example, the residence time for a separation operation, such as crystallization, refers to the time from when the crude acetosulfame potassium composition is introduced into the crystallization apparatus until the intermediate acetosulfame potassium composition is discharged from the crystallization apparatus.

[0025]

[0024] The treatment of the crude acetosulfame potassium composition can involve one or more operations, such as a concentration operation and / or a separation operation. Generally, a concentration operation is not regarded as a separation operation. In some embodiments, one or more concentration operations and one or more separation operations constitute the entire treatment of the crude acetosulfame potassium composition, thereby obtaining a purified acetosulfame potassium composition. In some cases, the entire concentration operation can include a plurality of individual concentration operations or units, and the entire separation operation can include a plurality of individual separation operations or units.

[0026]

[0025] As used herein, the "cyclization reaction time" refers to the time from the start of the supply of the acetoacetamide salt to the end of the supply of the acetoacetamide salt. In some cases, when indicated, the cyclization reaction time can include additional time after the end of the supply of the acetoacetamide salt, such as an additional 5 minutes or an additional 1 minute.

[0027]

[0026] As used herein, "wppm" and "wppb" mean parts per million by weight and parts per billion by weight, respectively, based on the total weight of the respective composition as a whole, such as the total weight of the entire crude acetosulfame potassium composition or the total weight of the entire purified acetosulfame potassium composition.

[0028] Formation of Acephate Potassium : A method for producing a high-purity acetosulfame potassium composition is described herein. In one aspect, the method includes preparing a crude acetosulfame potassium composition comprising acetosulfame potassium and acetoacetamide (present in an amount in the range of 1 wppb to 50 wppm in some cases); and treating the crude acetosulfame potassium composition to form a purified acetosulfame potassium composition. This treatment can include concentrating the crude acetosulfame potassium composition to form an intermediate acetosulfame potassium composition comprising a water stream, as well as acetosulfame potassium and a small amount of acetoacetamide; and then separating the intermediate acetosulfame potassium composition to form a purified acetosulfame potassium composition comprising acetosulfame potassium and a small amount of acetoacetamide. As described above, the crude acetosulfame potassium composition can be formed by reacting sulfamic acid with an amine to form an amidosulfamate, and then reacting the amidosulfamate with an acetoacetylating agent to form an acetoacetamide salt. Next, the acetoacetamide salt can be cyclized, hydrolyzed, and neutralized (and optionally phase-separated). These steps are described in more detail below.

[0029]

[0028] Importantly, in some aspects, some parameters of the concentration and / or separation operations are maintained within a specific level and / or a specific range. In some cases, the temperature at which the concentration and / or separation operations are performed is maintained at a low level. Also, in some aspects, the residence time (of the crude acetosulfame potassium composition in the concentration operation or of the intermediate acetosulfame potassium composition in the separation operation) is maintained at a low level. Without being bound by theory, as a result, during the process, for example, during the concentration and / or separation operations, little or no additional impurities, such as acetoacetamide, are generated, thereby providing a purer purified acetosulfame potassium composition. In some cases, the acetosulfame potassium composition in the purified acetosulfame potassium composition or in the intermediate acetosulfame potassium composition The weight percentage of toacetamide is lower than the weight percentage of acetoacetamide in the crude potassium asulam composition, that is, actually the acetoacetamide content decreases during the treatment.

[0030]

[0029] In some embodiments, one or more of the steps constituting the concentration operation, for example the concentration operation, are carried out at a low temperature, for example lower than 90 °C, for example lower than 88 °C, lower than 85 °C, lower than 83 °C, lower than 80 °C, lower than 78 °C, lower than 75 °C, lower than 73 °C, lower than 70 °C, lower than 65 °C, lower than 55 °C, lower than 50 °C, or lower than 46 °C, or maintained at such a temperature. In some cases, the temperature of the concentration operation can be maintained at a temperature higher than 0 °C, for example higher than 10 °C, higher than 15 °C, higher than 20 °C, higher than 22 °C, higher than 25 °C, higher than 35 °C, higher than 40 °C, or higher than 50 °C. Regarding the range, the temperature of the concentration operation can be in the range of 0 °C to 90 °C, for example 25 °C to 90 °C, 55 °C to 90 °C, 10 °C to 88 °C, 10 °C to 85 °C, 75 °C to 88 °C, 80 °C to 88 °C, 15 °C to 85 °C, 75 °C to 85 °C, 20 °C to 83 °C, 20 °C to 80 °C, 22 °C to 78 °C, 25 °C to 75 °C, 25 °C to 73 °C, 15 °C to 50 °C, 25 °C to 65 °C, 22 °C to 50 °C, 20 °C to 55 °C, 25 °C to 70 °C, or 30 °C to 60 °C.

[0031]

[0030] In some embodiments, one or more of the separation operations, e.g., the steps constituting the separation operation, are carried out at a low temperature, e.g., lower than 35°C, lower than 30°C, lower than 25°C, lower than 20°C, lower than 15°C, lower than 10°C, lower than 8°C, lower than 6°C, lower than 5°C, or lower than 0°C, or maintained at such a temperature. In some cases, the temperature of the separation operation can be maintained at a temperature higher than -25°C, e.g., higher than -10°C, higher than 0°C, higher than 5°C, higher than 10°C, higher than 15°C, higher than 25°C, or higher than 30°C. Regarding the range, the temperature of the separation operation can be in the range of -25°C to 35°C, e.g., -10°C to 35°C, 0°C to 35°C, 5°C to 30°C, -10°C to 30°C, -10°C to 25°C, -10°C to 20°C, -10°C to 15°C, 0°C to 25°C, or -10°C to 30°C. Using the above-mentioned temperature in the process advantageously improves the final product purity.

[0032]

[0031] In some embodiments, one or more of the concentration operations, e.g., the steps constituting the concentration operation, are carried out with a short residence time or maintained at such a time. In one embodiment, the residence time is less than 180 minutes, e.g., less than 170 minutes, less than 150 minutes, less than 120 minutes, less than 100 minutes, less than 90 minutes, less than 75 minutes, less than 50 minutes, less than 40 minutes, less than 30 minutes, less than 20 minutes, or less than 10 minutes. Regarding the lower limit, the residence time can be at least 1 second, e.g., at least 10 seconds, at least 1 minute, at least 10 minutes, or at least 15 minutes. Regarding the range, the residence time can be in the range of 1 second to 180 minutes, e.g., 10 seconds to 180 minutes, 1 minute to 180 minutes, 10 minutes to 150 minutes, 1 minute to 50 minutes, 1 minute to 30 minutes, 10 minutes to 100 minutes, 1 minute to 80 minutes, 10 minutes to 80 minutes, 10 minutes to 50 minutes, 15 minutes to 90 minutes, or 15 minutes to 75 minutes. The same limits and ranges of residence time can be applied to one or more of the separation operations, e.g., the steps constituting the separation operation. By using the residence time in the concentration operation and / or the separation operation, the final product purity is advantageously improved.

[0033]

[0032] In some embodiments, one or more of the steps constituting the concentration operation, for example the concentration operation, is carried out or maintained at a low pH. In one embodiment, the pH of the separation is maintained below 10.0, for example below 9.5, below 9.0, below 8.5, below 8.0, below 7.5, below 7.0, or below 6.5. With respect to the range, the pH of the concentration operation is preferably maintained between 6.0 and 10.0, for example between 6.5 and 9.5, between 7.0 and 9.0, or between 7.5 and 8.5. The same pH limits and ranges can be applied to the separation operation, for example one or more of the steps constituting the separation operation. By using a low pH level in the concentration operation or the separation operation, the final product purity is advantageously improved.

[0034]

[0033] When evaporation is used in the concentration operation, the evaporation can be carried out within the temperature limits and ranges described above. In addition to the benefit of reducing the above-mentioned impurities, by using a lower evaporation temperature, the formation of solids in the evaporator, such as solid acesulfame potassium (which can cause safety problems, such as the accumulation of unnecessary pressure, or the explosion of the evaporator) is surprisingly limited or eliminated.

[0035]

[0034] The above parameter limits and ranges can be applied to the individual concentration or separation operations that can make up the entire concentration or separation operation. For example, when the concentration operation may include evaporation, the evaporation can be carried out at a temperature lower than 90 °C, such as lower than 88 °C, lower than 85 °C, lower than 83 °C, lower than 80 °C, lower than 78 °C, lower than 75 °C, lower than 73 °C, lower than 70 °C, lower than 65 °C, lower than 55 °C, lower than 50 °C, or lower than 46 °C. As another example, when the concentration operation may include evaporation, the evaporation can be carried out with a residence time of less than 180 minutes, such as less than 170 minutes, less than 150 minutes, less than 120 minutes, less than 100 minutes, less than 90 minutes, less than 75 minutes, less than 50 minutes, less than 40 minutes, less than 30 minutes, less than 20 minutes, or less than 10 minutes. As another example, when the separation operation includes crystallization, the crystallization can be carried out at a pH lower than 10.0, such as lower than 9.5, lower than 9.0, lower than 8.5, lower than 8.0, lower than 7.5, lower than 7.0, or lower than 6.5.

[0036]

[0035] By carrying out the treatment under the parameters of temperature, pH, and / or residence time discussed here, the stress on the potassium acesulfame molecules (in the crude potassium acesulfame composition) during the separation operation is advantageously minimized. As a result, during the separation operation, less potassium acesulfame decomposes into acetoacetamide. Thus, the intermediate potassium acesulfame composition and the purified potassium acesulfame composition advantageously contain an amount of impurities, such as acetoacetamide, that is less than the amount that would normally be formed by the decomposition of potassium acesulfame (even if present).

[0037]

[0036] In some embodiments, the concentration operation comprises evaporating the crude potassium acesulfame composition to form an intermediate potassium acesulfame composition comprising a water stream, potassium acesulfame, and less than 75 wt%, such as less than 50 wt%, less than 40 wt%, less than 30 wt%, less than 20 wt%, less than 15 wt%, less than 10 wt%, less than 5 wt%, less than 3 wt%, or less than 1 wt% water. The water stream can refer to water that evaporates from the crude potassium acesulfame composition, e.g., water that is not present in the intermediate potassium acesulfame composition. Evaporation can be carried out at the concentration operation parameters mentioned herein.

[0038]

[0037] In some cases, the separation comprises crystallizing the intermediate potassium acesulfame composition or a derivative thereof to form a purified potassium acesulfame composition that may be in the form of potassium acesulfame crystals (or a composition / stream comprising potassium acesulfame crystals). The intermediate potassium acesulfame composition can be a stream or composition obtained from the concentration of the crude potassium acesulfame composition. Crystallization can be carried out at the separation operation parameters mentioned herein.

[0039]

[0038] In some embodiments, the separation comprises filtering the intermediate potassium acesulfame composition (or a crystal-containing derivative thereof) to form a purified potassium acesulfame composition. The crystal-containing derivative of the intermediate potassium acesulfame composition can be a stream or composition obtained from the concentration of the crude potassium acesulfame composition and comprising crystals in either dissolved or solid form. Filtration can be carried out at the separation operation parameters mentioned herein.

[0040]

[0039] In a preferred embodiment, the overall process evaporates the crude potassium acesulfame composition to form a water stream, as well as potassium acesulfame and a small amount (refer to the above limits / ranges) of water forming an intermediate acetosulfame potassium composition comprising; crystallizing the intermediate acetosulfame potassium composition to form acetosulfame potassium crystals; and filtering the acetosulfame potassium crystals to form a purified acetosulfame potassium composition; are included.

[0041]

[0040] In one aspect, the method comprises preparing a crude acetosulfame potassium composition comprising acetosulfame potassium, acetoacetamide, and water; and evaporating the crude acetosulfame potassium composition to form a water stream and the intermediate acetosulfame potassium composition (disclosed above). In this aspect, the residence time of the crude acetosulfame potassium composition in the evaporator is less than 180 minutes, such as less than 170 minutes, less than 150 minutes, less than 120 minutes, less than 100 minutes, less than 90 minutes, less than 75 minutes, less than 50 minutes, less than 40 minutes, less than 30 minutes, less than 20 minutes, or less than 10 minutes. With respect to the range, the residence time may be in the range of 1 second to 180 minutes, such as 10 seconds to 180 minutes, 1 minute to 180 minutes, 10 minutes to 150 minutes, 10 minutes to 100 minutes, 10 minutes to 80 minutes, 10 minutes to 50 minutes, 15 minutes to 90 minutes, or 15 minutes to 75 minutes.

[0042]

[0041] In some aspects, the formation of the purified acetosulfame potassium composition from the intermediate acetosulfame potassium composition comprises crystallizing the intermediate acetosulfame potassium composition to form acetosulfame potassium crystals and filtering the crystal-containing stream to form the purified acetosulfame potassium composition. In a preferred aspect, a falling-film evaporator is used to form the intermediate acetosulfame potassium composition.

[0043]

[0042] The crude acetosulfame composition may further contain a solvent. In some embodiments, the concentration operation includes a solvent removal step, for example, stripping the solvent from the crude potassium acetosulfame composition before concentration (evaporation). This method can include the steps of preparing a crude potassium acetosulfame composition; stripping the crude potassium acetosulfame composition to form a solvent stream containing the solvent and a stripped potassium acetosulfame composition containing less than 50% by weight, for example, less than 40% by weight, less than 30% by weight, less than 20% by weight, less than 15% by weight, less than 10% by weight, less than 5% by weight, less than 3% by weight, or less than 1% by weight of the solvent, and then performing the above-mentioned concentration operation and separation operation. It has been found that by removing the solvent, such as methylene dichloride, the concentration efficiency increases surprisingly. In addition to the stripping step, the separation operation can further include evaporation, crystallization, and / or filtration steps.

[0044]

[0043] In some embodiments, the separation operation includes the step of crystallizing an intermediate potassium acetosulfame composition to form a crystal-containing stream containing potassium acetosulfame crystals. Crystallization can be carried out within the pH range and limits discussed above. This method can further include the step of forming a purified potassium acetosulfame composition from the crystal-containing stream. In some embodiments, the forming step includes filtering the crystal-containing stream to form a purified potassium acetosulfame composition. This embodiment can also use the above-mentioned solvent stripping step.

[0045]

[0044] When filtration is used in the separation operation, the filtration is preferably carried out within the temperature limits and ranges of the separation operation discussed herein. When crystallization is used in the separation operation, the crystallization can be carried out within the temperature limits and ranges discussed herein.

[0046] In addition to the temperature limits and ranges, crystallization can be carried out within the pH limits and ranges discussed herein. For example, crystallization can be carried out at a pH lower than 10.0, such as lower than 9.5, lower than 9.0, lower than 8.5, lower than 8.0, lower than 7.5, lower than 7.0, or lower than 6.5. In addition to the benefit of reducing the formation of acetoacetamide, separation of the dimer that may form in side reactions is also found to be improved by carrying out crystallization. Lower pH levels are thought to promote precipitation of the dimer. Higher pH levels are known to promote the solubility of the dimer. Precipitation provides the more efficient separation advantageously.

[0047] In addition to the temperature limits and ranges, crystallization can be carried out within the residence time limits and ranges discussed herein.

[0047] In one aspect, preparing a crude acephate composition (to be subsequently concentrated and separated) involves reacting sulfamic acid with an amine to form an amidosulfamate, and reacting the amidosulfamate with an acetoacetylating agent to form an acetoacetamide salt. Next, the acetoacetamide salt can be reacted with a cyclizing agent, optionally in the presence of a solvent, to form a cyclic (sulfur trioxide) adduct composition. In a preferred aspect, preparing a crude acephate composition further involves hydrolyzing a cyclic sulfur trioxide adduct to form acepham-H, and neutralizing the acepham-H to form a crude acephate composition. In some aspects, the neutralization step involves reacting acepham-H (optionally in the acepham-H composition) with a neutralizing agent to form an acephate composition. This reaction can include reacting acepham-H with a neutralizing agent. The acephate composition contains acephate and impurities. Formation of the cyclic sulfur trioxide adduct can produce a cyclic sulfur trioxide adduct composition containing the cyclic sulfur trioxide adduct, as well as further reaction by-products and impurities. Similarly, formation of acepham-H can produce an acepham-H composition containing acepham-H, as well as further reaction by-products and impurities.

[0048]

[0048] The specific methods used to impart the desired temperature and / or residence time characteristics can vary widely. With respect to temperature, a heat exchange device, such as a cooling device, can be used. Methods for maintaining temperature are well known in the art.

[0049]

[0049] With respect to residence time, appropriate valves, gauges, metering devices, and piping can be used to control each separation stream to maintain the residence time discussed herein.

[0050] The potassium asulam composition formed by one or more of the processes described herein will be a high-purity potassium asulam composition. For example, this potassium asulam composition may contain an amount of acetoacetamide salt as discussed above.

[0050] Acephate Potassium Composition :

[0051] The crude potassium asulam composition is formed by hydrolyzing a cyclic sulfur trioxide adduct to form an asulam-H composition and neutralizing the asulam-H in the asulam-H composition to form the crude potassium asulam composition, as discussed herein. The product of the neutralization step is phase-separated into an aqueous phase and an organic phase. The crude potassium asulam composition can be obtained from the aqueous phase (without further purification). The crude potassium asulam composition contains potassium asulam and acetoacetamide, for example less than 2800 wppm, for example less than 2700 wppm, less than 2600 wppm, less than 2500 wppm, less than 2400 wppm, less than 2000 wppm, less than 1500 wppm, less than 1000 wppm, less than 500 wppm, or less than 100 wppm of acetoacetamide. In some cases, the crude potassium asulam composition is substantially free of (undetectable) acetoacetamide, for example contains no acetoacetamide. With respect to ranges, the crude potassium asulam composition may contain 1 wppm to 2800 wppm, for example 1 wppm to 2700 wppm, 10 wppm to 2700 wppm, 20 wppm to 2500 wppm, 100 wppm to 2500 wppm, 500 wppm to 2500 wppm, 1500 to 2400 wppm, 500 wppm to 2375 wppm, 600 wppm to 2000 wppm, 900 to 1900 wppm, 300 wppm to 1500 wppm, 400 w ppm to 1400 wppm, 600 wppm to 1200 wppm, or 700 wppm to 1100 wppm of acetoacetamide.

[0051]

[0052] The crude potassium asulam composition may further contain acetoacetamide-N-sulfonic acid, which may be present in the amounts discussed above with respect to acetoacetamide.

[0053] The purified potassium asulam composition, which is usually suitable for end consumer use, is formed by treating the crude potassium asulam composition as discussed herein to remove impurities. This purified potassium asulam composition preferably comprises a mixture of potassium asulam and less than 33 wppm, such as less than 32 wppm, less than 30 wppm, less than 25 wppm, less than 20 wppm, less than 15 wppm, less than 12 wppm, less than 10 wppm, less than 7 wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, less than 0.8 wppm, less than 0.5 wppm, or less than 0.3 wppm of acetoacetamide. In some cases, the purified potassium asulam composition substantially does not contain acetoacetamide, for example, does not contain acetoacetamide. With respect to the range, the purified potassium asulam composition may contain 1 wppb to 33 wppm, such as 10 wppb to 32 wppm, 10 wppb to 25 wppm, 10 wppb to 15 wppm, 10 wppb to 12 wppm, 10 wppb to 10 wppm, 10 wppb to 7 wppm, 10 wppb to 5 wppm, 10 wppb to 3 wppm, 100 wppb to 15 wppm, 100 wppb to 10 wppm, or 100 wppb to 5 wppm of acetoacetamide.

[0052]

[0054] The purified acetosulfame potassium composition preferably contains acetosulfame potassium and less than 33 wppm, such as less than 32 wppm, less than 30 wppm, less than 25 wppm, less than 20 wppm, less than 15 wppm, less than 12 wppm, less than 10 wppm, less than 7 wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, less than 0.8 wppm, less than 0.5 wppm, or less than 0.3 wppm of acetoacetamide-N-sulfonic acid. In some cases, the purified acetosulfame potassium composition substantially does not contain acetoacetamide-N-sulfonic acid, for example, does not contain acetoacetamide-N-sulfonic acid. Regarding the range, the purified acetosulfame potassium composition may contain 1 wppb to 33 wppm, such as 10 wppb to 32 wppm, 10 wppb to 25 wppm, 1 wppb to 22 wppm, 10 wppb to 22 wppm, 1 wppb to 20 wppm, 10 wppb to 20 wppm, 10 wppb to 15 wppm, 10 wppb to 12 wppm, 10 wppb to 10 wppm, 10 wppb to 7 wppm, 10 wppb to 5 wppm, 10 wppb to 3 wppm, 100 wppb to 15 wppm, 100 wppb to 10 wppm, or 100 wppb to 5 wppm of acetoacetamide-N-sulfonic acid.

[0053]

[0055] The content of acetoacetamide-N-sulfonic acid and / or acetoacetamide in the crude composition, intermediate composition, or purified composition of acetosulfame potassium can be measured by high-performance liquid chromatography (HPLC) analysis based on the European Pharmacopoeia guidelines on thin-layer chromatography (2017) (compatible with HPLC). The specific measurement method uses an LC Systems HPLC unit manufactured by Shimadzu with a CBM-20 Shimadzu controller, equipped with an IonPac NS1 ((5μm) 150 ×4 mm) analytical column and an IonPac NG1 guard column (35×4.0 mm). For detection (at wavelengths of 270 nm and 280 nm), a Shimadzu SPD-M20A photodiode array detector can be used. It can be carried out. The analysis can be performed at a column temperature of 23 °C. As the first eluent, an aqueous mixture of tetrabutylammonium hydrogen sulfate (3.4 g / L), acetonitrile (300 mL / L), and potassium hydroxide (0.89 g / L) can be used; as the second eluent, an aqueous mixture of tetrabutylammonium hydrogen sulfate (3.4 g / L) and potassium hydroxide (0.89 g / L) can be used. Elution can be carried out in gradient mode according to the following second eluent flow profile. It can be done.

[0054] · 0 - 3 minutes: constant at 80% (v / v); · 3 - 6 minutes: linearly decrease to 50% (v / v); · 6 - 15 minutes: constant at 50% (v / v); · 15 - 18 minutes: linearly decrease to 0%; · 18 - 22 minutes: constant at 0%; · 22 - 24 minutes: linearly increase to 80% (v / v); · 24 - 35 minutes: constant at 80% (v / v). The total flow rate of the eluent may be about 1.2 mL / min. Data collection and calculation can be carried out using LabSolution software manufactured by Shimadzu.

[0055]

[0056] For example, during the concentration operation, one or more intermediate potassium acesulfame compositions can be formed, for example, by evaporation. The intermediate potassium acesulfame composition preferably comprises a mixture of potassium acesulfame and less than 33 wppm, for example less than 30 wppm, less than 25 wppm, less than 20 wppm, less than 15 wppm, less than 12 wppm, less than 10 wppm, less than 7 wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, less than 0.8 wppm, less than 0.5 wppm, or less than 0.3 wppm of acetoacetamide. In some cases, the intermediate potassium acesulfame composition does not contain acetoacetamide, for example, is substantially free of (undetectable) acetoacetamide. With respect to the range, the intermediate potassium acesulfame composition can contain 1 wppb to 33 wppm, for example 10 wppb to 30 wppm, 10 wppb to 25 wppm, 10 wppb to 15 wppm, 10 wppb to 12 wppm, 10 wppb to 10 wppm, 10 wppb to 7 wppm, 10 wppb to 5 wppm, 10 wppb to 3 wppm, 100 wppb to 15 wppm, 100 wppb to 10 wppm, or 100 wppb to 5 wppm of acetoacetamide. The intermediate potassium acesulfame composition can contain a mixture of potassium acesulfame and acetoacetamide.

[0056]

[0057] As described above, the crude potassium asulam composition is formed by the above-mentioned reaction, hydrolysis, and neutralization. As discussed herein, the crude potassium asulam composition is concentrated to form an intermediate potassium asulam composition, which is then separated to form a purified potassium asulam composition. In a preferred embodiment, the temperature at which the concentration operation, such as evaporation, is carried out is 90 °C or lower, for example lower than 88 °C, lower than 85 °C, lower than 83 °C, lower than 80 °C, lower than 78 °C, lower than 75 °C, lower than 73 °C, lower than 70 °C, lower than 65 °C, lower than 55 °C, lower than 50 °C, or lower than 46 °C (in some cases, a temperature in the range of 0 °C to 90 °C, for example 25 °C to 90 °C, 55 °C to 90 °C, 10 °C to 88 °C, 10 °C to 85 °C, 75 °C to 88 °C, 80 °C to 88 °C, 15 °C to 85 °C, 75 °C to 85 °C, 20 °C to 83 °C, 20 °C to 80 °C, 22 °C to 78 °C, 25 °C to 75 °C, 25 °C to 73 °C, 15 °C to 50 °C, 25 °C to 65 °C, 22 °C to 50 °C, 20 °C to 55 °C, 25 °C to 70 °C, or 30 °C to 60 °C); the concentration operation uses a residence time of less than 180 minutes, for example less than 170 minutes, less than 150 minutes, less than 120 minutes, less than 100 minutes, less than 90 minutes, less than 75 minutes, less than 50 minutes, less than 40 minutes, less than 30 minutes, less than 20 minutes, or less than 10 minutes (in some cases, a residence time in the range of 1 second to 180 minutes, for example 10 seconds to 180 minutes, 1 minute to 180 minutes, 10 minutes to 150 minutes, 1 minute to 50 minutes, 1 minute to 30 minutes, 10 minutes to 100 minutes, 10 minutes to 80 minutes, 10 minutes to 50 minutes, 15 minutes to 90 minutes, or 15 minutes to 75 minutes); the temperature at which the separation operation, such as crystallization and / or filtration, is carried out is lower than 35 °C, for example lower than 30 °C, lower than 25 °C, lower than 20 °C, lower than 15 °C, lower than 10 °C, lower than 8 °C, lower than 6 °C, lower than 5 °C, or lower than 0 °C (in some cases, a temperature in the range of -25 °C to 35 °C, for example -10 °C to 35 °C, 0 °C to 35 °C, 5 °C to 30 °C, -10 °C to 30 °C, -10 °C to 25 °C, -10 °C to 20 °C, -10 °C to 15 °C, 0 °C to 25 °C, or -10 °C to 30 °C); The separation operation uses a residence time of less than 180 minutes, such as less than 170 minutes, less than 150 minutes, less than 120 minutes, less than 100 minutes, less than 90 minutes, less than 75 minutes, less than 50 minutes, less than 40 minutes, less than 30 minutes, less than 20 minutes, or less than 10 minutes (in some cases, a residence time in the range of 1 second to 180 minutes, such as 10 seconds to 180 minutes, 1 minute to 180 minutes, 10 minutes to 150 minutes, 10 minutes to 100 minutes, 1 minute to 80 minutes, 10 minutes to 80 minutes, 10 minutes to 50 minutes, 15 minutes to 90 minutes, or 15 minutes to 75 minutes is used); the crude potassium acetosulfamate composition contains less than 2800 wppm, such as less than 2700 wppm, less than 2600 wppm, less than 2500 wppm, less than 2400 wppm, less than 2000 wppm, less than 1500 wppm, less than 1000 wppm, less than 500 wppm, or less than 100 wppm of acetoacetamide (in some cases, it may contain 1 wppm to 2800 wppm, such as 1 wppm to 2800 wppm, 10 wppm to 2700 wppm, 20 wppm to 2500 wppm, 100 wppm to 2500 wppm, 500 wppm to 2500 wppm, 1500 to 2400 wppm, 500 wppm to 2375 wppm, 600 wppm to 2000 wppm, 900 to 1900 wppm, 300 wppm to 1500 wppm, 400 wppm to 1400 wppm, 600 wppm to 1200 wppm, or 700 wppm to 1100 wppm of acetoacetamide); the intermediate potassium acetosulfamate composition contains less than 33 wppm, such as less than 32 wppm, less than 30 wppm, less than 25 wppm, less than 20 wppm, less than 15 wppm, less than 12 wppm, less than 10 wppm, less than 7 wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, less than 0.8 wppm, less than 0.5 wppm, or 0.Less than 3 wppm of acetoacetamide (optionally, 1 wppb to 33 wppm, such as 10 wppb to 32 wppm, 10 wppb to 25 wppm, 10 wppb to 15 wppm, 10 wppb to 12 wppm, 10 wppb to 10 wppm, 10 wppb to 7 wppm, 10 wppb to 5 wppm, 10 wppb to 3 wppm, 100 wppb to 15 wppm, 100 wppb to 10 wppm, or 100 wppb to 5 wppm of acetoacetamide) may be included (the intermediate acesulfame potassium composition may contain the same amount of acetoacetamide-N-sulfonic acid); the purified acesulfame potassium composition is less than 33 wppm, such as less than 32 wppm, less than 30 wppm, less than 25 wppm, less than 20 wppm, less than 15 wppm, less than 12 wppm, less than 10 wppm, less than 7 wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, less than 0.8 wppm, less than 0.5 wppm, or less than 0.3 wppm of acetoacetamide (optionally, 1 wppb to 33 wppm, such as 10 wppb to 32 wppm, 10 wppb to 25 wppm, 10 wppb to 15 wppm, 10 wppb to 12 wppm, 10 wppb to 10 wppm, 10 wppb to 7 wppm, 10 wppb to 5 wppm, 10 wppb to 3 wppm, 100 wppb to 15 wppm, 100 wppb to 10 wppm, 100 wppb to 5 wppm of acetoacetamide) may be included (the purified acesulfame potassium composition may contain the same amount of acetoacetamide-N-sulfonic acid).

[0057]

[0058] In certain embodiments, the concentration operation, such as evaporation, is performed at a temperature lower than 85°C, the intermediate acesulfame potassium composition contains 1 wppb to 33 wppm of acetoacetamide (and optionally less than 33 wppm of acetoacetamide-N-sulfonic acid), and the purified acesulfame potassium composition contains less than 33 wppm of acetoacetamide (and optionally less than 33 wppm of acetoacetamide-N-sulfonic acid).

[0058]

[0059] In other specific embodiments, the concentration operation, such as evaporation, is carried out at a temperature lower than 60°C, the residence time in the evaporator is less than 50 minutes, the intermediate potassium acesulfame composition contains 10 wppb to 25 wppm of acetoacetamide (and optionally less than 30 wppm of acetoacetamide-N-sulfonic acid), and the purified potassium acesulfame composition contains 10 wppb to 15 wppm of acetoacetamide (and optionally less than 30 wppm of acetoacetamide-N-sulfonic acid).

[0059]

[0060] In other specific embodiments, the concentration operation, such as evaporation, is carried out at a temperature lower than 46°C, the residence time in the evaporator is less than 30 minutes, the crystallization is carried out at a temperature lower than 35°C, the intermediate potassium acesulfame composition contains 10 wppb to 12 wppm of acetoacetamide (and optionally less than 20 wppm of acetoacetamide-N-sulfonic acid), and the purified potassium acesulfame composition contains 10 wppb to 7 wppm of acetoacetamide.

[0060]

[0061] In other specific embodiments, the concentration operation, such as evaporation, is carried out at a temperature in the range of 25°C to 90°C, the residence time in the evaporator is in the range of 10 seconds to 180 minutes, the separation operations, such as crystallization and filtration, are carried out at a temperature in the range of -10°C to 35°C, the residence time of the separation operations is in the range of 10 seconds to 180 minutes, the crude potassium acesulfame composition contains 1 wppm to 2800 wppm of acetoacetamide and 1 wppm to 2800 wppm of acetoacetamide-N-sulfonic acid, the intermediate potassium acesulfame composition contains 1 wppb to 33 wppm of acetoacetamide and 1 wppb to 33 wppm of acetoacetamide-N-sulfonic acid, and the purified potassium acesulfame composition contains 1 wppb to 33 wppm of acetoacetamide and 1 wppb to 33 wppm of acetoacetamide-N-sulfonic acid.

[0061]

[0062] In other specific embodiments, the concentration operation, such as evaporation, is carried out at a temperature in the range of 25°C to 90°C, the evaporator residence time is in the range of 10 seconds to 180 minutes, the separation operation, such as crystallization and filtration, is carried out at a temperature in the range of -10°C to 35°C, the separation operation residence time is in the range of 10 seconds to 180 minutes, the crude acetosulfame potassium composition contains 1 wppm to 2800 wppm of acetoacetamide and 1 wppm to 2800 wppm of acetoacetamide-N-sulfonic acid, the intermediate acetosulfame potassium composition contains 1 wppb to 33 wppm of acetoacetamide and 1 wppb to 33 wppm of acetoacetamide-N-sulfonic acid, and the purified acetosulfame potassium composition contains 1 wppb to 33 wppm of acetoacetamide and 1 wppb to 33 wppm of acetoacetamide-N-sulfonic acid.

[0062]

[0063] In other specific embodiments, the concentration operation, such as evaporation, is carried out at a temperature in the range of 20°C to 55°C, the evaporator residence time is in the range of 1 minute to 300 minutes, the separation operation, such as crystallization and filtration, is carried out at a temperature in the range of -10°C to 15°C, the separation operation residence time is in the range of 1 to 180 minutes, the crude acetosulfame potassium composition contains 500 wppm to 2375 wppm of acetoacetamide, the intermediate acetosulfame potassium composition contains 10 wppb to 20 wppm of acetoacetamide and 10 wppb to 20 wppm of acetoacetamide-N-sulfonic acid, and the purified acetosulfame potassium composition contains 10 wppb to 10 wppm of acetoacetamide and 1 wppb to 20 wppm of acetoacetamide-N-sulfonic acid.

[0063]

[0064] Acephate potassium compositions (crude compositions and / or purified compositions) may, in some cases, contain organic impurities. Among the organic impurities, haloacephate potassium can be mentioned in particular. Acephate potassium compositions (crude compositions and / or purified compositions) may also contain heavy metals. The organic impurities and / or heavy metals may be present in amounts in the range of 1 wppb to 25 wppm, for example 100 wppb to 20 wppm, 100 wppb to 15 wppm, 500 wppb to 10 wppm, or 1 wppm to 5 wppm, based on the total weight of each acephate potassium composition (crude composition or purified composition). Heavy metals are defined as metals having a relatively high density, for example higher than 3 g / cm 3 higher, or higher than 7 g / cm 3 . Representative heavy metals include lead and mercury. In some cases, the crude or purified acephate potassium composition may contain mercury in amounts in the range of 1 wppb to 25 wppm, for example 100 wppb to 20 wppm, 100 wppb to 15 wppm, 500 wppb to 10 wppm, or 1 wppm to 5 wppm. Regarding the limit, the crude or purified acephate potassium composition may contain less than 25 wppm, for example less than 20 wppm, less than 15 wppm, less than 10 wppm, or less than 5 wppm of mercury. In some cases, the crude or purified acephate potassium composition may contain lead in amounts in the range of 1 wppb to 25 wppm, for example 100 wppb to 20 wppm, 100 wppb to 15 wppm, 500 wppb to 10 wppm, or 1 wppm to 5 wppm. Regarding the limit value, the crude or purified acephate potassium composition may contain less than 25 wppm, for example less than 20 wppm, less than 15 wppm, less than 10 wppm, or less than 5 wppm of lead. In some cases, when potassium hydroxide is formed by a membrane process, the resulting crude or purified acephate potassium composition may have a very low level of mercury, for example less than 10 wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, less than 500 wppb, or less than 100 wppb of mercury, even if present.

[0064] Intermediate Reaction Parameters :

[0065] The reaction for producing high-purity acephate potassium is described in more detail below.

[0065] Amidosulfamic Acid Salt Formation Reaction :

[0066] In the first reaction step, sulfamic acid and an amine are reacted to form a sulfamate. A typical reaction scheme for producing triethylammonium sulfamate using triethylamine as the amine is shown in the following reaction (1).

[0066]

Chemical formula

[0067]

[0067] Acetic acid is also present in the first reaction mixture, and as shown in the following reaction (2), this reacts with an amine, for example triethylamine, to form triethylammonium acetate.

[0068]

Chemical formula

[0069]

[0068] The amines used in these reactions may vary widely. Preferably, the amine includes triethylamine. In one embodiment, the amine can be selected from the group consisting of trimethylamine, diethylpropylamine, tri-n-propylamine, triisopropylamine, ethyldiisopropylamine, tri-n-butylamine, triisobutylamine, tricyclohexylamine, ethyldicyclohexylamine, N,N-dimethylaniline, N,N-diethylaniline, benzyldimethylamine, pyridine, substituted pyridines such as picoline, lutidine, collidine, or methylethylpyridine, N-methylpiperidine, N-ethylpiperidine, N-methylmorpholine, N,N-dimethylpiperazine, 1,5-diazabicyclo[4.3.0]-non-5-ene, 1,8-diazabicyclo[5.4.0]-undec-7-ene, 1,4-diazabicyclooctane, tetramethylhexamethylenediamine, tetramethylethylenediamine, tetramethylpropylenediamine, tetramethylbutylenediamine, 1,2-dimorpholylethane, pentamethyldiethyltriamine, pentaethyldiethylenetriamine, pentamethyldipropylenetriamine, tetramethyldiaminomethane, tetrapropyldiaminomethane, hexamethyltriethylenetetramine, hexamethyltripropylenetetramine, diisobutylenetriamine, triisopropylenetriamine, and mixtures thereof.

[0070] Acetoacetamide Salt Formation Reaction :

[0069] Once formed in reaction (1), the sulfamate is reacted with an acetoacetylating agent to form an acetoacetamide salt, preferably an acetoacetamide-N-sulfonate triethylammonium salt. Preferably, the acetoacetylating agent includes diketene, but other acetoacetylating agents can be used with or without diketene.

[0071]

[0070] In one embodiment, the resulting acetoacetamide salt corresponds to the following formula (3).

[0072]

Chemical formula

[0073]

[0071] In the formula, M + is a suitable ion. Preferably, M + is an alkali metal ion or N + R 1 R 2 R 3 R 4 is. R 1 , R 2 , R 3 and R 4 are, independently of one another, an organic group or hydrogen, preferably H, or C 1 ~C 8 alkyl, C 6 ~C 10 cycloalkyl, aryl, and / or aralkyl. In a preferred embodiment, R 1 is hydrogen, and R 2 , R 3 , and R 4 are alkyl, for example ethyl.

[0074]

[0072] A representative reaction scheme for forming the acetoacetamide salt is to use trialkylammonium amide sulfate and diketene as reactants to produce the acetoacetamide triethylammonium salt as shown in the following reaction (4).

[0075]

Chemical formula

[0076]

[0073] In one embodiment, the reaction is carried out in the presence of a catalyst (which may vary widely). In some embodiments, the catalyst comprises one or more amines and / or phosphines. Preferably, the catalyst comprises triethylamine. In some cases, trimethylamine acts as both a catalyst and a reactant.

[0077]

[0074] In one embodiment where the amidosulfamic acid salt formation reaction and the acetoacetamide salt formation reaction are carried out in separate reactors, the second reaction mixture comprises an amidosulfamic acid salt, diketene, and a catalyst such as triethylamine. Preferably, the catalyst is carried over from the first reaction to the reaction mixture of the second reaction. Next, the second reaction mixture is subjected to conditions effective to form the acetoacetamide salt.

[0078]

[0075] In one embodiment, the composition of the second reaction mixture may be the same as the composition of the first reaction mixture. In a preferred embodiment, the reaction product of the amidosulfamic acid salt formation reaction provides the amidosulfamic acid salt component of the second reaction mixture. In addition to the above components, the second reaction mixture may further contain reaction by-products from the first reaction or unreacted starting materials.

[0079]

[0076] In one embodiment, the amount of the acetoacetylating agent, such as diketene, must be at least equimolar to the amidosulfamic acid salt of the reactants supplied. In one embodiment, this process can use an excess of diketene, but the excess amount is preferably less than 30 mol%, for example less than 10 mol%. Larger excess amounts are also contemplated.

[0080]

[0077] The amidosulfamic acid salt formation reaction and / or the acetoacetamide salt formation reaction can use an organic solvent. Suitable inert organic solvents include any organic solvent that does not react in an undesirable form with the starting materials, cyclizing agents, final products, and / or catalysts in the reaction. The solvent preferably has the ability to at least partially dissolve the amidosulfamic acid salt. Representative organic solvents preferably include halogenated aliphatic hydrocarbons having 4 or fewer carbon atoms, such as methylene chloride, chloroform, 1,2-dichloroethane, trichloroethylene, tetrachloroethylene, trichlorofluoroethylene; aliphatic ketones, preferably those having 3 to 6 carbon atoms, such as acetone, methyl ethyl ketone; aliphatic ethers, preferably cyclic aliphatic ethers having 4 or 5 carbon atoms, such as tetrahydrofuran, dioxane; lower aliphatic carboxylic acids, preferably those having 2 to 6 carbon atoms, such as acetic acid, propionic acid; aliphatic nitriles, preferably acetonitrile; N-alkyl-substituted amides of carbonic acid and lower aliphatic carboxylic acids, preferably amides having 5 or fewer carbon atoms, such as tetramethylurea, dimethylformamide, dimethylacetamide, N-methylpyrrolidone; aliphatic sulfoxides, preferably dimethyl sulfoxide, and aliphatic sulfones, preferably sulfolane.

[0081]

[0078] Particularly preferred solvents include dichloromethane (methylene chloride), 1,2-dichloroethane, acetone, glacial acetic acid, and dimethylformamide, with dichloromethane (methylene chloride) being particularly preferred. The solvent can be used either alone or as a mixture. In one embodiment, the solvent is a halogenated aliphatic hydrocarbon solvent, preferably the solvent is dichloromethane. Chloroform and carbon tetrachloride are also representative solvents.

[0082]

[0079] In one embodiment, the acetoacetamide salt formation reaction is carried out at a temperature in the range of -30°C to 50°C, for example, 0°C to 25°C. The reaction pressure can be widely varied. In a preferred embodiment, the reaction is carried out at atmospheric pressure, although other pressures are also contemplated. The reaction time can be widely varied, preferably in the range of 0.5 hours to 12 hours, for example, 1 hour to 10 hours. In one embodiment, the reaction is carried out by introducing amidosulfamic acid salt and metering in diketene. In other embodiments, the reaction is carried out by introducing diketene and metering in amidosulfamic acid salt. The reaction can be carried out by introducing diketene and amidosulfamic acid and metering in a catalyst.

[0083]

[0080] Once formed, the respective reaction products are optionally subjected to one or more purification steps. For example, the solvent can be separated from the reaction product, for example, by distillation, and the residue (mainly acetoacetamide-N-sulfonate) can be recrystallized from a suitable solvent such as acetone, methyl acetate, or ethanol.

[0084] Cyclization and Hydrolysis :

[0081] The acetoacetamide salt is reacted with a cyclizing agent, for example, the cyclizing agent in a cyclizing agent composition, in the presence of a solvent to form a cyclic sulfur trioxide adduct and, in some cases, a cyclic (sulfur trioxide) adduct composition containing impurities. In some cases, a cooling step is carried out prior to the cyclic sulfur trioxide adduct formation reaction. In one embodiment, the cyclization is carried out by using at least an equimolar amount of the cyclizing agent. The cyclizing agent can be dissolved in an inert inorganic or organic solvent. The cyclizing agent is generally used in a molar excess, for example, 20-fold or less excess, or 10-fold or less excess based on the total number of moles of the acetoacetamide salt. A representative cyclization reaction using sulfur trioxide as the cyclizing agent is shown in the following reaction (5).

[0085]

Chemical formula

[0086]

[0082] In one aspect, the weight ratio of the solvent to the cyclizing agent in the cyclizing agent composition is at least 1:1, for example at least 2:1, or at least 5:1. In one aspect, the weight ratio of the solvent to the cyclizing agent in the cyclizing agent composition ranges from 1:1 to 25:1, for example from 1:1 to 10:1, from 2:1 to 10:1, or from 5:1 to 10:1.

[0087]

[0083] The cyclizing agent may be any compound that initiates the ring closure of the acetoacetamide salt. Sulfur trioxide is a preferred cyclizing agent, but the use of other cyclizing agents is contemplated.

[0084] The cyclizing agent can be added to the reaction mixture either in solid or liquid form, or by condensing it in vapor. Suitable inert inorganic or organic solvents are sulfur trioxide, or a liquid that does not react with the starting materials or final products of the reaction in an undesirable form. Preferred organic solvents include preferably halogenated aliphatic hydrocarbons having 4 or fewer carbon atoms, such as methylene chloride (dichloromethane), chloroform, 1,2-dichloroethane, trichloroethylene, tetrachloroethylene, trichlorofluoroethylene; esters of carbonic acid and lower aliphatic alcohols, preferably methanol or ethanol; nitroalkanes preferably having 4 or fewer carbon atoms, especially nitromethane; alkyl-substituted pyridines, preferably collidine; and aliphatic sulfones, preferably sulfolane, but are not limited thereto. Particularly preferred solvents for the cyclization reaction include dichloromethane (methylene chloride), 1,2-dichloroethane, acetone, glacial acetic acid, and dimethylformamide, and dichloromethane (methylene dichloride) is particularly preferred. Other solvents, such as other solvents mentioned herein, may also be suitable as solvents. The solvent can be used either alone or as a mixture. In one aspect, the solvent is a halogenated aliphatic hydrocarbon solvent, and preferably the solvent is dichloromethane. This process can use these solvents either alone or as a mixture thereof.

[0088]

[0085] In some cases, the solvent in the cyclizing agent composition can be selected from (1) concentrated sulfuric acid, (2) liquid sulfur dioxide, or (3) an inert organic solvent.

[0086] In a preferred embodiment, the same solvent is used in both the acetoacetamide salt formation reaction and the cyclization reaction. As one advantage, the solution obtained in the acetoacetamide salt formation reaction can be used directly in the cyclization without isolating the acetoacetamide salt formation reaction product.

[0089]

[0087] In one embodiment, the reaction temperature for the cyclization reaction is in the range of -70 °C to 175 °C, for example -40 °C to 60 °C. The pressure at which the reaction is carried out can vary widely. In one embodiment, the reaction is carried out at a pressure in the range of 0.01 MPa to 10 MPa, for example 0.1 MPa to 5 MPa. Preferably, the reaction is carried out at atmospheric pressure.

[0090]

[0088] The acetoacetamide salt can be introduced into the cyclization reactor, and a cooled cyclizing agent composition, for example a solution of the cyclizing agent in a solvent in some cases, can be metered into the reactor. In a preferred embodiment, both reactants (the acetoacetamide salt and the cyclizing agent) are fed into the reactor simultaneously. In one embodiment, first the cooled cyclizing agent composition is introduced into the reactor and the acetoacetamide salt is added. Preferably, at least a portion of the cyclizing agent composition is introduced into the reactor, and then, preferably while maintaining the temperature described above, the acetoacetamide salt and (additional) cyclizing agent are metered in continuously or in portions several times.

[0091]

[0089] The acetoacetamide salt can be introduced into the reactor, and the cyclizing agent composition can be metered into the reactor. In a preferred embodiment, both reactants are fed into the reactor simultaneously. In one embodiment, first the cyclizing agent composition is introduced into the reactor and the acetoacetamide salt is added. Preferably, at least a portion of the cyclizing agent composition is introduced into the reactor, and then, preferably while maintaining the temperature described above, the acetoacetamide salt and (additional) cyclizing agent are metered in continuously or in portions several times.

[0092]

[0090] In some embodiments, the formation of the crude potassium asulam composition from the cyclic sulfur trioxide adduct composition comprises the steps of hydrolyzing the cyclic sulfur trioxide adduct to form an asulam-H composition; neutralizing asulam-H in the asulam-H composition to form a crude potassium asulam composition; and forming a potassium asulam composition from the crude potassium asulam composition.

[0093]

[0091] The cyclic sulfur trioxide adduct can be hydrolyzed by conventional means, for example, using water. Thus, the formation step can include the step of hydrolyzing the cyclic sulfur trioxide adduct to form an asulam-H composition. Asulam-H is called a sweetener acid.

[0094]

[0092] A representative hydrolysis reaction scheme is shown in the following reaction (6).

[0095]

Chemical formula

[0096]

[0093] Phase separation is caused by adding water. Most of the sweetener acid asulam-H (6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide) formed by hydrolysis, for example, at least 60 wt%, at least 70%, at least 80%, or at least 90% is present in the organic phase. The remainder of the sweetener acid is present in the aqueous phase, which can be extracted and optionally added to the sweetener acid in the organic phase. When dichloromethane is used as the reaction medium, for example, a molar excess of water or ice based on sulfur trioxide can be added to the cyclic sulfur trioxide adduct / sulfur trioxide solution.

[0097]

[0094] In some cases, the hydrolysis step involves adding water to the cyclic sulfur trioxide adduct. In a preferred embodiment, the weight ratio of water to acetoacetamide salt is higher than 1.3:1, for example higher than 1.5:1, higher than 1.7:1, higher than 2:1, or higher than 2.2:1. By using these ratios, it is possible to result in a decrease in the formation of acetoacetamide-N-sulfonic acid and / or acetoacetamide in the neutralized crude potassium acesulfame composition, for example, the crude potassium acesulfame composition can contain the amount of acetoacetamide-N-sulfonic acid discussed herein.

[0098]

[0095] Surprisingly, the temperature at which water is first supplied to the hydrolysis reaction, as well as the reaction parameters, such as temperature, can have a beneficial effect on the formation of impurities, such as the formation of organic substances, or the formation of 5-chloro-acesulf am potassium. It has been found that at lower temperatures, for example lower than about -35°C, or lower than -22°C, ice tends to accumulate in the reaction mixture. As this ice melts, the initiation of further reactions is caused and the temperature rapidly rises. This temperature rise surprisingly resulted in a product containing a much higher level of impurities. In some cases, hydrolysis involves adding hydrolysis water to the cyclic sulfur trioxide adduct to form a hydrolysis reaction mixture, and reacting this mixture to form an acesulfame-H composition. In some embodiments, the temperature of the hydrolysis reaction mixture, or the temperature at which the hydrolysis water is supplied to the reactor, is maintained at a temperature higher than -35°C, for example higher than -30°C, higher than -25°C, higher than -24°C, higher than -23°C, higher than -22°C, higher than -21.5°C, higher than -21°C, or higher than -20°C. Regarding the range, the temperature of the hydrolysis reaction mixture, or the temperature at which the hydrolysis water is supplied to the reactor, is in some cases maintained at a temperature in the range of -35°C to 0°C, for example -30°C to -5°C, -20°C to -5°C, -30°C to -20°C, -25°C to -21°C, or -25°C to -21.5°C.

[0099]

[0096] After adding water, the reaction solvent, such as dichloromethane, can be removed by distillation, or the acesulfame-H remaining in the organic phase can be extracted with a more suitable solvent. The suitable solvent is sufficiently stable to sulfuric acid and has a satisfactory dissolving ability. Other suitable solvents include esters of carbonic acid, such as dimethyl carbonate, diethyl carbonate, and ethylene carbonate, or esters of organic monocarboxylic acids, such as isopropyl formate and isobutyl formate, ethyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, and neopentyl acetate, or esters of dicarboxylic acids or amides immiscible with water, such as tetrabutyl urea. Isopropyl acetate and isobutyl acetate are particularly preferred.

[0100]

[0097] Here, it has been found that in addition to the organic sweetener acid-dichloromethane phase and the aqueous phase, a transfer phase can be formed. The transfer phase can contain a large amount of impurities, such as acetoacetamide. The transfer phase can contain a larger amount of such impurities than the organic phase. Advantageously, this transfer phase can be removed from the organic sweetener acid-dichloromethane phase, thereby greatly reducing its impurity content. This process can use the step of phase-separating the acesulfame-H composition. By phase separation, a sweetener acid-dichloromethane phase, an aqueous phase, and the above-mentioned transfer phase containing at least 2% by weight, such as at least 5% by weight, at least 10% by weight, at least 20% by weight, at least 30% by weight, or at least 50% by weight of impurities can be formed. This process can include separating the transfer phase from the acesulfame-H composition to form a purified acesulfame-H composition. Next, a purified acesulfame potassium composition can be formed from the purified acesulfame-H composition, for example, by neutralization and treatment.

[0101]

[0098] Combine the organic phases, for example, Na 2 SO 4Dry and evaporate. By appropriately adding an aqueous alkali solution to the organic phase, the sulfuric acid carried over in the extraction can be removed. For this purpose, an aqueous dilute alkali solution can be added to the organic phase until the pH reached in the aqueous phase corresponds to that of pure 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide at the same concentration in the same two-phase system of the extractant and water.

[0102] Neutralization :

[0099] By neutralizing acesulfame-H, a non-toxic salt of acesulfame-H, such as potassium acesulfame, is produced. In one embodiment, the neutralization is carried out by reacting acesulfame-H with a suitable base, such as potassium hydroxide, especially potassium hydroxide produced by the membrane method. Other suitable bases include, for example, KOH, KHCO 3 、K 2 CO 3 、and potassium alcoholate. A typical reaction scheme using potassium hydroxide as the neutralizing agent is shown in the following reaction (7).

[0103]

Chemical formula

[0104]

[0100] In some cases, the neutralization is carried out at a low pH level or maintained at such a pH level, which can advantageously further result in a reduction or elimination of the formation of impurities, such as acetoacetamide salts. In this context, "carried out" means starting the neutralization process at a low pH level, and "maintained" means carrying out the process such that the pH is reliably maintained within a low pH range throughout the neutralization process. In one embodiment, the neutralization process is carried out at a pH lower than 10.0, for example lower than 9.5, lower than 9.0, lower than 8.5, lower than 8.0, lower than 7.5, lower than 7.0, or lower than 6.5, or maintained at such a pH. With respect to the range, the neutralization process is preferably carried out at a pH between 6.0 and 10.0, for example between 6.5 and 9.5, between 7.0 and 9.0, or between 7.5 and 8.5, or maintained at such a pH.

[0105]

[0101] In some cases, the pH during the neutralization process can be maintained within the desired range by manipulating the components of the neutralization reaction mixture containing acesulfame-H and the neutralizing agent (and further the solvent). For example, the composition of the neutralization reaction mixture can include 1 wt% to 95 wt%, for example 10 wt% to 85 wt%, or 25 wt% to 75 wt% of the neutralizing agent; and 1 wt% to 95 wt%, for example 10 wt% to 85 wt%, or 25 wt% to 75 wt% of acesulfame-H. These concentration ranges are based on the mixture of the neutralizing agent and acesulfame-H (excluding the solvent).

[0106]

[0102] In one embodiment, an aqueous potassium base solution can be used to neutralize acesulfame-H and directly extract it from the purified organic extraction phase. Next, potassium acesulfame can be precipitated in crystalline form, if appropriate, after evaporation of the solution, which can also be recrystallized for purification.

[0107]

[0103] In one aspect, this process is not a small-scale batch process or a laboratory-scale process. For example, the method of the present invention for producing a purified acetosulfame potassium composition can produce at least 50 grams, such as at least 100 grams, at least 500 grams, at least 1 kilogram, or at least 10 kilograms of the purified acetosulfame potassium composition per batch. With respect to speed, the method of the present invention can produce at least 50 grams, such as at least 100 grams, at least 500 grams, at least 1 kilogram, or at least 10 kilograms of the purified acetosulfame potassium composition per hour.

[0108]

[0104] Figure 1 shows a representative acetosulfame potassium process 100 according to the method described herein. Process 100 includes a sulfamic acid amide formation reactor 102 and an acetoacetamide salt formation reactor 104. Although Figure 1 shows separate reactors for two intermediate formation reactions, other configurations, such as a one-reactor process, are within the scope of the intent of this method. Sulfamic acid is supplied to the sulfamic acid amide formation reactor 102 through the sulfamic acid supply line 106. One or more amines, preferably triethylamine, are supplied to the sulfamic acid amide formation reactor 102 through the amine supply line 108. In addition to sulfamic acid and one or more amines, acetic acid is also supplied to the sulfamic acid amide formation reactor 102 (through the supply line 110). The reaction mixture obtained in the sulfamic acid amide formation reactor 102 is as discussed above. In the sulfamic acid amide formation reactor 102, sulfamic acid and an amine are reacted (in the presence of acetic acid) to produce a crude sulfamic acid amide salt composition, which is discharged from the reactor 102 through line 112. Although not shown, a reaction solvent, such as dichloromethane, can also be present in the sulfamic acid amide formation reactor 102.

[0109]

[0105] Send the crude amidosulfamate composition within line 112 to the acetoacetamide salt forming reactor 104. Through supply line 114, supply diketene to the acetoacetamide salt forming reactor 104. Within the acetoacetamide salt forming reactor 104, react the amidosulfamate with diketene to produce a crude acetoacetamide salt composition and discharge it from the reactor 104 through line 118. Although not shown, dichloromethane can also be present within the acetoacetamide salt forming reactor 104.

[0110]

[0106] Through supply lines 121 and 123, supply the cyclizing agent (sulfur dioxide) and the solvent (dichloromethane) to container 119. Container 119 is preferably a container in which a cyclizing agent composition containing these two components is formed. Discharge the cyclizing agent composition containing both the cyclizing agent and the solvent from container 119 through line 125.

[0111]

[0107] Through line 118, send the crude acetoacetamide salt composition to the cyclizing reactor 120. Also, send the cyclizing agent composition (through line 125) to the cyclizing reactor 120. Line 125 is preferably formed of the materials discussed here and with dimensions and a shape that facilitate the residence time discussed here. Within the cyclizing reactor 120, cyclize the acetoacetamide salt in the crude acetoacetamide salt composition within line 118 and discharge an annular sulfur trioxide adduct stream through line 124.

[0112]

[0108] The cyclic sulfur trioxide adduct in line 124 is sent to hydrolysis reactor 126. Water is supplied to hydrolysis reactor 126 through water supply line 128. In hydrolysis reactor 126, the cyclic sulfur trioxide adduct is hydrolyzed to produce a crude ace sulfam-H composition, which is discharged from hydrolysis reactor 126 through line 130 and sent to phase separation unit 132. Phase separation unit 132 separates the contents of line 130 into an organic phase 134 and an aqueous phase 136. Organic phase 134 contains a major amount of ace sulfam-H in line 130 and a solvent such as methylene chloride. Aqueous phase 136 is discharged through line 137, which contains triethylammonium sulfate and, optionally, sulfuric acid and a small amount of ace sulfam-H. The aqueous phase can be further purified to separate and / or recover ace sulfam-H and / or triethylammonium sulfate. The recovered ace sulfam-H can be combined with the ace sulfam from the organic phase (not shown).

[0113]

[0109] The organic phase 134 is discharged from phase separation unit 132 and sent to extraction column 138 (through line 140). Water is supplied to extraction column 138 through water supply line 142. The residual sulfate is extracted from the contents of line 140 with water, and the purified ace sulfam-H composition is discharged from extraction column 138 through line 144. The extracted sulfate is discharged from extraction column 138 through line 145.

[0114]

[0110] The purified asulam-H composition within line 144 is sent to neutralization unit 146. Potassium hydroxide is also supplied to neutralization unit 146 (through line 148). The addition of potassium hydroxide to neutralization unit 146 (by line 148) can be adjusted to achieve and / or maintain the desired pH level during the neutralization discussed herein. The asulam-H in the asulam-H composition purified by potassium hydroxide is neutralized, producing a product containing potassium asulam, dichloromethane, water, potassium hydroxide, and impurities such as acetoacetamide, which is discharged from neutralization unit 146 through line 150. This product can be regarded as a crude potassium asulam composition.

[0115]

[0111] The crude potassium asulam product stream within line 150 can be sent to treatment zone 156 to recover purified potassium asulam (as shown to be discharged by stream 152). In addition to purified potassium asulam, dichloromethane and potassium hydroxide can be separated from the crude potassium asulam product stream as shown by stream 154. The contents of stream 154 can be recovered and / or recycled to the process. Treatment zone 156 can include one or more of the treatment steps described herein, such as stripping, evaporation, crystallization, and filtration.

[0116]

[0112] The product within line 150 is sent to phase separation unit 160. Phase separation unit 160 separates the product within line 150 into an organic phase 162 and an aqueous phase 164. Aqueous phase 164 contains a major amount of potassium asulam within line 150 and some impurities. Organic phase 162 contains potassium hydroxide, dichloromethane, and water, and these components can be further processed to recover them. Aqueous phase 164 (without further treatment) can be regarded as a crude potassium asulam composition. Aqueous phase 164 can optionally be treated to form a purified potassium asulam composition.

[0117]

[0113] The aqueous phase 164 is sent to the processing unit 156 through line 166. Within the processing unit 156, the aqueous phase 164 is processed to obtain a purified acephate potassium composition (a product that can be sold) (shown to be discharged through stream 152). In addition to the purified acephate potassium composition, dichloromethane and potassium hydroxide can be separated. These components are discharged from the processing unit 156 through line 154. The contents of stream 154 can be recovered and / or recycled to the process.

[0118]

[0114] Figure 2 shows a representative processing area. The crude acephate potassium product stream 250 is supplied to the processing area 256. In particular, the crude acephate potassium product stream 250 is supplied to the stripper 252 to strip the solvent therefrom. The solvent in stream 254 is discharged from the stripper 252 and sent for further processing, such as reuse or recycling. The stripped acephate potassium stream 257 contains a small amount of solvent, which is discharged from the stripper 252 and sent to the evaporator 258. It has been found that by removing the solvent prior to evaporation, unexpectedly improved benefits of the evaporation operation are provided.

[0119]

[0115] The evaporator 258 removes water from the stripped acephate potassium stream in line 257 to form a water stream 260 and an intermediate acephate potassium composition stream 262. The evaporator 258 is preferably a falling-film evaporator. The intermediate acephate potassium composition stream 262 is sent to the crystallizer 264 to generate a crystal-containing stream 266 and a recycle stream 268. The crystal-containing stream 266 is then sent to the filtration unit 270 to filter out impurities and generate a purified acephate potassium composition stream 272 and an impurity stream 274. The processing unit can be beneficially operated with the separation parameters discussed herein.

[0120]

[0116] The present invention also relates to the following forms.

[0117] Form 1: A method for manufacturing a purified acephate potassium composition, comprising (a) Preparing a crude acetosulfame potassium composition containing acetosulfame potassium, acetoacetamide, and water; (b) Concentrating the crude acetosulfame potassium composition to form an intermediate acetosulfame potassium composition containing a water stream, acetosulfame potassium, and less than 33 wppm of acetoacetamide; (c) Separating the intermediate acetosulfame potassium composition to form a purified acetosulfame potassium composition containing acetosulfame potassium and less than 33 wppm of acetoacetamide; comprising; The above method, wherein the concentration step (b) is carried out at a temperature lower than 90 °C, and the separation step (c) is carried out at a temperature of 35 °C or lower.

[0121]

[0118] Form 2: The preparing step (a) is reacting sulfamic acid with an amine to form an amidosulfamic acid salt; reacting the amidosulfamic acid salt with an acetoacetylating agent to form an acetoacetamide salt; reacting the acetoacetamide salt with a cyclizing agent in a cyclizing agent composition to form a cyclic sulfur trioxide adduct; hydrolyzing the cyclic sulfur trioxide adduct to form an acetosulfame-H composition containing acetosulfame-H; and neutralizing the acetosulfame-H in the acetosulfame-H composition to form a crude acetosulfame potassium composition; The method of Form 1, comprising.

[0122]

[0119] Form 3: The method according to any one of the above forms, wherein the intermediate acetosulfame potassium composition contains less than 33 wppm of acetoacetamide-N-sulfonic acid.

[0120] Form 4: The method according to any one of the above forms, wherein the concentration comprises evaporating the crude acetosulfame potassium composition to form an intermediate acetosulfame potassium composition containing a water stream, acetosulfame potassium, and less than 75% by weight of water.

[0123]

[0121] Form 5: Any of the methods of the above forms where the evaporation residence time is less than 180 minutes.

[0122] Form 6: Any of the methods of the above forms where the intermediate potassium acesulfame composition contains less than 33 wppm of acetoacetamide-N-sulfonic acid.

[0124]

[0123] Form 7: The separation comprises: crystallizing the intermediate potassium acesulfame composition to form potassium acesulfame crystals; and filtering the potassium acesulfame crystals to form a purified potassium acesulfame composition; Any of the methods of the above forms.

[0125]

[0124] Form 8: Any of the methods of the above forms where the filtration is carried out at a temperature of 35°C or lower.

[0125] Form 9: Any of the methods of the above forms where the crystallization is carried out at a temperature of 35°C or lower.

[0126] Form 10: Any of the methods of the above forms where the crystallization is carried out at a pH lower than 10.

[0126]

[0127] Form 11: The evaporation is carried out at a temperature lower than 85°C, the intermediate potassium acesulfame composition contains 1 wppb to 33 wppm of acetoacetamide, and the purified potassium acesulfame composition contains less than 33 wppm of acetoacetamide. Any of the methods of the above forms.

[0127]

[0127]

[0128] Form 12: Any of the methods of the above forms where the intermediate potassium acesulfame composition further contains less than 33 wppm of acetoacetamide-N-sulfonic acid.

[0129] Form 13: The evaporation is carried out at a temperature lower than 60°C, the evaporation residence time is less than 50 minutes, the intermediate potassium acesulfame composition contains 10 wppb to 25 wppm of acetoacetamide, and the purified potassium acesulfame composition contains 10 wppb to 15 wppm of acetoacetamide. Any of the methods of the above forms.

[0128]

[0130] Form 14: Any of the methods of the above forms, wherein the intermediate acephate potassium composition contains less than 30 wppm of acetoacetamide-N-sulfonic acid.

[0131] Form 15: Any of the methods of the above forms, wherein the evaporation is carried out at a temperature in the range of 20°C to 55°C; the residence time in the evaporator is in the range of 1 minute to 300 minutes; the separation is carried out at a temperature in the range of -10°C to 15°C; the residence time of the separation operation is in the range of 1 to 180 minutes; the crude acephate potassium composition contains 500 wppm to 2375 wppm of acetoacetamide; the intermediate acephate potassium composition contains 10 wppb to 20 wppm of acetoacetamide and 10 wppb to 20 wppm of acetoacetamide-N-sulfonic acid; and the purified acephate potassium composition contains 10 wppb to 10 wppm of acetoacetamide and 1 wppb to 20 wppm of acetoacetamide-N-sulfonic acid.

[0129]

[0132] Form 16: (i) the evaporation is carried out at a temperature lower than 46°C; (ii) the residence time in the evaporator is less than 30 minutes; (iii) the crystallization is carried out at a temperature lower than 35°C; (iv) the intermediate acephate potassium composition contains 10 wppb to 12 wppm of acetoacetamide; and (v) the purified acephate potassium composition contains 10 wppb to 7 wppm of acetoacetamide.

[0130]

[0133] Form 17: Any of the methods of the above forms, wherein the intermediate acephate potassium composition contains less than 20 wppm of acetoacetamide-N-sulfonic acid.

[0134] Form 18: Any of the methods of the above forms, wherein the crude acephate potassium composition further contains a solvent, and the method further includes removing the solvent from the crude acephate potassium composition before the evaporation.

[0131]

[0135] Form 19: A method according to any of the preceding forms, wherein the weight percentage of acetoacetamide in the purified acephate potassium composition is lower than the weight percentage of acetoacetamide in the crude acephate potassium composition.

[0132]

[0136] Form 20: Separating a transfer phase containing at least 2% by weight of acetoacetamide from the acephate-H composition to form a purified acephate-H composition; A method according to any of the preceding forms, further comprising this.

[0133]

[0137] Form 21: A method according to any of the preceding forms, wherein the neutralization comprises neutralizing acephate-H in the purified acephate-H composition to form a crude acephate potassium composition containing acephate potassium and acetoacetamide.

[0134]

[0138] Form 22: The concentration evaporates the crude acephate potassium composition to form a water stream and an intermediate acephate potassium composition containing acephate potassium and less than 50% by weight of water. The separation comprises crystallizing the intermediate acephate potassium composition to form a crystal-containing stream containing acephate potassium crystals, and filtering the crystal-containing stream to form the purified acephate potassium composition. A method according to any of the preceding forms.

[0135]

[0139] Form 23: A method according to any of the preceding forms, wherein the filtration comprises at least two filtration operations.

[0140] Form 24: A purified acephate potassium composition that can be produced, is being produced, or can be obtained, or is obtained by a method according to any of Forms 1 to 22.

[0136]

[0141] Form 25: A method for producing a purified acephate potassium composition, comprising (a) Step of reacting sulfamic acid with triethylamine to form an amidosulfamic acid salt; (b) Step of reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt; (c) Step of contacting dichloromethane with sulfur trioxide to form a cyclizing agent composition; (d) Step of reacting the acetoacetamide salt with sulfur trioxide in the cyclizing agent composition to form a cyclic sulfur trioxide adduct; (e) Step of hydrolyzing the cyclic sulfur trioxide adduct to form an acesulfame-H composition; (f) Step of neutralizing the acesulfame-H to form a crude acesulfame potassium composition containing acesulfame potassium and acetoacetamide; (g) Step of evaporating the crude acesulfame potassium composition to form an intermediate acesulfame potassium composition containing a water stream, as well as acesulfame potassium and less than 75% by weight of water; (h) Step of crystallizing the intermediate acesulfame potassium composition to form acesulfame potassium crystals; and (i) Step of filtering the acesulfame potassium crystals to form a purified acesulfame potassium composition containing acesulfame potassium and less than 10 wppm of acetoacetamide; comprising; The above method, wherein the evaporation is carried out at a temperature lower than 50°C and the residence time in the evaporator is less than 30 minutes.

[0137]

[0142] Form 26: The method of Form 24, wherein the filtration is carried out at a temperature lower than 35°C and the crystallization is carried out at a temperature lower than 35°C.

[0143] Form 27: A purified acesulfame potassium composition that can be produced by or can be produced or obtained by the method of Form 24 or 25.

[0138]

[0144] Form 28: An acesulfame potassium composition containing acesulfame potassium and less than 33 wppm, preferably less than 10 wppm, of acetoacetamide.

[0145] Form 29: A potassium acesulfame composition of Form 27 or 28 further comprising acetoacetamide-N-sulfonic acid in an amount of less than 29.33 wppm, preferably less than 10 wppm.

[0139]

[0146] Form 30: A potassium acesulfame composition of any one of Forms 27 to 29 further comprising 0.001 wppm to 5 wppm of organic impurities and / or 0.001 wppm to 5 wppm of at least one heavy metal.

[0140]

[0147] Form 31: A potassium acesulfame composition of Forms 27 to 30, wherein the at least one heavy metal is selected from the group consisting of mercury, lead, and mixtures thereof.

[0148] Form 31: A potassium acesulfame composition of Forms 27 to 31, wherein the mercury is present in an amount of 1 wppb to 20 wppm.

[0141]

[0149] Form 31: A potassium acesulfame composition of Forms 27 to 32, wherein the lead is present in an amount of 1 wppb to 25 wppm.

Examples

[0142]

[0150] The following examples are included to illustrate the processes and compositions and are not intended to limit the scope of the present application. Formation of Crude Acephate Potassium Composition :

[0151] 100 mmol of sulfamic acid with a purity of 99.5% was suspended in 50 mL of dichloromethane in a flask while refluxing. With continuous stirring, 105 mmol of trimethylamine was added within about 3 minutes. During this time, the temperature rose to about 42 °C (the boiling point of dichloromethane) due to the acid / base exothermic reaction. This first reaction mixture was stirred for an additional about 15 minutes until no solid precipitate was visible in the flask. Next, 10 mmol of acetic acid was added to the first reaction mixture and stirred for an additional about 15 minutes. At this point, 110 mmol of diketene was added dropwise within 7 minutes of acetic acid addition to form a second reaction mixture. After adding all of the diketene to the second reaction mixture and after a reaction time of about 15 minutes, the second reaction mixture was cooled. The resulting cooled second reaction mixture contained about 30% of the triethylammonium salt of acetoacetamide-N-sulfonate. Additional batches of the cooled second reaction mixture were prepared as needed.

[0143]

[0152] In a separate container, an iodine trioxide / dichloromethane composition containing about 15 wt% iodine trioxide and about 85 wt% dichloromethane was prepared by bringing the two components into contact with each other.

[0144]

[0153] The second flask (a four-neck round-bottom flask equipped with a mechanical stirrer, a thermometer, and a feed vessel) was placed in a cooling bath containing a mixture of isopropanol and dry ice. Approximately 200 g of an acetoacetamide-N-sulfonate triethylammonium salt solution and approximately 577 g of a sulfur trioxide / dichloromethane composition were weighed. First, approximately 15 wt% (about 87 g) of the entire sulfur trioxide / dichloromethane composition was fed into the reaction flask under continuous stirring with a mechanical stirrer. When the temperature of the flask contents reached -35 °C (by the cooling bath), the remainder of the sulfur trioxide / dichloromethane composition and all of the acetoacetamide-N-sulfonate triethylammonium salt solution were fed into the second flask. The time when the solvent came into contact with the cyclizing agent before the formation of the cyclic sulfur trioxide adduct, for example, before the acetoacetamide-N-sulfonate triethylammonium salt solution was fed into the second flask, was less than 1 hour. The feeding rate was controlled so that the temperature of the contents of the second flask was maintained between -25 °C and -35 °C during the feeding / cyclization reaction. After feeding the reactants, the reaction was allowed to proceed for an additional approximately 1 minute. Next, the cooling bath was removed.

[0145]

[0154] After approximately 1 minute, the temperature of the flask contents reached approximately -22 °C. At this point, hydrolysis was initiated by feeding deionized water into the flask. The water was fed over a period of 10 minutes. The hydrolysis reaction was exothermic. The water was added slowly so that the temperature was maintained between -20 °C and -5 °C. After adding the water, the reaction mixture was allowed to reach room temperature.

[0146]

[0155] The hydrolysis product was phase-separated using a separatory funnel. The heavier organic sweetener acid-dichloromethane phase (acesulfame-H composition) was separated and removed, and the remaining aqueous phase was discarded.

[0147]

[0156] The acetosulfam-H in the acetosulfam-H composition was neutralized with a 10% potassium hydroxide solution. The neutralization was carried out at 25°C ± 1°C. The addition of potassium hydroxide was completed within 20 minutes. After the neutralization process was completed, further phase separation was carried out using a separatory funnel to obtain an aqueous phase containing potassium acetosulfamate (and some impurities) and an organic phase. The aqueous phase was regarded as the crude potassium acetosulfamate composition. This crude potassium acetosulfamate composition was divided into two parts and treated as discussed below. The remaining dichloromethane in the organic phase was discarded.

[0148] Example 1: Evaporation / Crystallization :

[0157] The first part of the crude potassium acetosulfamate composition was evaporated in a rotary evaporator at 45°C under reduced pressure for about 20 minutes. As a result, about 50% of the water evaporated from the crude potassium acetosulfamate composition. After removing the water, an intermediate potassium acetosulfamate composition remained. Next, the intermediate potassium acetosulfamate composition was separated and cooled to 5°C, for example, in a refrigerator.

[0149]

[0158] Upon cooling, crude crystals containing mostly potassium acetosulfamate precipitated. These crude crystals were regarded as the purified potassium acetosulfamate composition. The crude crystals were separated from the liquid and analyzed for yield and impurities, such as acetoacetamide. Tests for acetoacetamide (AAA) content were carried out using the HPLC apparatus and techniques discussed here. In particular, the HPLC analysis was performed using an LC Systems HPLC unit manufactured by Shimadzu, which had a CBM-20 Shimadzu controller and was equipped with an IonPac NS1 ((5μm) 150 × 4 mm) analytical column and an IonPac NG1 guard column (35 × 4.0 mm). A Shimadzu SPD-M20A photodiode array detector was used for detection (at wavelengths of 270 nm and 280 nm). Sep The analysis was performed at a column temperature of 23°C. As the first eluent, an aqueous mixture of tetrabutylammonium hydrogen sulfate (3.4 g / L), acetonitrile (300 mL / L), and potassium hydroxide (0.89 g / L) was used; as the second eluent, an aqueous mixture of tetrabutylammonium hydrogen sulfate (3.4 g / L) and potassium hydroxide (0.89 g / L) was used. The elution was carried out in gradient mode according to the following second eluent flow profile.

[0150] · 0 - 3 minutes: constant at 80% (v / v); · 3 - 6 minutes: linearly decreasing to 50% (v / v); · 6 - 15 minutes: constant at 50% (v / v); · 15 - 18 minutes: linearly decreasing to 0%; · 18 - 22 minutes: constant at 0%; · 22 - 24 minutes: linearly increasing to 80% (v / v); · 24 - 35 minutes: constant at 80% (v / v). The total flow rate of the eluent was about 1.2 mL / min. Data collection and calculation were performed using Shimadzu's LabSolution software.

[0151] Comparative Example A: Evaporation / Crystallization :

[0159] The second part of the crude potassium acetosulfamate composition was evaporated in a rotary evaporator at 90°C under reduced pressure for about 180 minutes. As a result, about 50% of the water evaporated from the crude potassium acetosulfamate composition. After removing the water, an intermediate potassium acetosulfamate composition remained. Next, the intermediate potassium acetosulfamate composition was separated, for example, by cooling to 5°C in a refrigerator.

[0152]

[0160] Upon cooling, crude crystals containing mostly potassium acetosulfamate precipitated. These crude crystals were regarded as the purified potassium acetosulfamate composition. The crude crystals were separated from the liquid and analyzed for yield and impurities, such as acetoacetamide. Regarding the acetoacetamide content The tests to be conducted were carried out using the HPLC apparatus and techniques discussed above. The results regarding Example 1 and Comparative Example A are shown in Table 1.

[0153]

Table 1

[0154]

[0161] The temperature of the concentration of the crude potassium asulam composition and the separation operation of the intermediate potassium asulam composition affects the formation of acetoacetamide. Without being bound by theory, it is considered that acetoacetamide impurities are formed as a result of thermal stress during the high-temperature concentration of the crude potassium asulam composition, for example, during the initial evaporation process. As shown, when the temperature of the concentration operation is maintained below 90 °C, no further separation after crystallization is necessary to maintain the acetoacetamide content below a suitable level, for example, less than 10 wppm.

[0155] Example 2 and Comparative Examples B - D :

[0162] Also, the decomposition effects of temperature and pH on the potassium asulam composition during the treatment were studied. Potassium asulam was diluted in water sufficient to form a 16% aqueous solution. This aqueous solution was divided into a plurality of portions (Example 2 and Comparative Examples B - D). These portions of the aqueous solution (except for Example 2) were heated under reflux condensation to simulate the concentration operation. In Comparative Example D, before heating, a small amount of 10% potassium hydroxide was added to each portion of the aqueous solution to adjust the pH of the resulting solution to about 9.8. For each portion, crystals (intermediate potassium asulam composition) were removed from the remaining liquid (after heating), and analyzed for impurities formed by decomposition, such as acetoacetamide-N-sulfonic acid (AAA-NSH). The tests regarding the acetoacetamide-N-sulfonic acid content were carried out using the HPLC apparatus and techniques discussed above. The treatment conditions and the obtained impurity contents are shown in Table 2.

[0156]

Table 2

[0157]

[0163] As shown in Table 2, during conventional concentration operating conditions, the use of high temperature, long heating times (simulating residence times), and high pH causes the decomposition of potassium acesulfame (or acesulfame-H), which results in the formation of further impurities, such as acetoacetamide-N-sulfonic acid. By using the concentration operating parameters discussed herein, the impurities formed during decomposition are reduced or eliminated, thereby resulting in a purified potassium acesulfame composition of higher purity, i.e., a purified potassium acesulfame composition having a low acetoacetamide-N-sulfonic acid content.

[0158]

[0164] While the invention has been described in detail, modifications within the spirit and scope of the invention will readily occur to those skilled in the art. Considering the above discussion, the relevant knowledge in the art, and the references discussed above in connection with the background and detailed description (all of these disclosures are incorporated herein by reference). Further, it should be understood that in the above and / or the appended claims, the various forms of the invention as well as the multiple parts of the various aspects and various features shown can be combined or exchanged fully or partially. As will be recognized by those skilled in the art, in the above description of the various aspects, these aspects showing other aspects can be appropriately combined with other aspects. Further, those skilled in the art will recognize that the above description is for illustrative purposes only and is not intended to limit the invention. The description of the claims of the original application of this application at the time of filing is transcribed below. [1] A method for producing a purified potassium acesulfame composition, comprising: (a) preparing a crude potassium acesulfame composition comprising potassium acesulfame, acetoacetamide, and water; (b) concentrating the crude potassium acesulfame composition to form a water stream and an intermediate potassium acesulfame composition comprising potassium acesulfame and less than 33 wppm of acetoacetamide; (c) Separating the intermediate acesulfame potassium composition to form the purified acesulfame potassium composition containing acesulfame potassium and less than 33 wppm of acetoacetamide; comprising; The method as described above, wherein the concentration step (b) is carried out at a temperature lower than 90 °C and the separation step (c) is carried out at a temperature of 35 °C or lower. [2] The step (a) of preparing is reacting sulfamic acid with an amine to form an amidosulfamate; reacting the amidosulfamate with an acetoacetylating agent to form an acetoacetamide salt; reacting the acetoacetamide salt with a cyclizing agent in a cyclizing agent composition to form a cyclic sulfur trioxide adduct; hydrolyzing the cyclic sulfur trioxide adduct to form an acesulfame-H composition containing acesulfame-H; and neutralizing the acesulfame-H in the acesulfame-H composition to form the crude acesulfame potassium composition; The method according to [1], comprising. [3] The method according to [1], wherein the intermediate acesulfame potassium composition contains less than 33 wppm of acetoacetamide-N-sulfonic acid. [4] The concentration is evaporating the crude acesulfame potassium composition to form a water stream and the intermediate acesulfame potassium composition containing acesulfame potassium and less than 75% by weight of water; The method according to [1], comprising. [5] The method according to [4], wherein the evaporation residence time is less than 180 minutes. [6] The method according to [5], wherein the intermediate acesulfame potassium composition contains less than 33 wppm of acetoacetamide-N-sulfonic acid. [7] The separation is crystallizing the intermediate acesulfame potassium composition to form acesulfame potassium crystals; and Filtering the acephate potassium crystals to form the purified acephate potassium composition; The method according to [4], comprising. [8] The method according to [7], wherein the filtration is carried out at a temperature of 35 °C or lower. [9] The method according to [7], wherein the crystallization is carried out at a temperature of 35 °C or lower.

[10] The method according to [7], wherein the crystallization is carried out at a pH lower than 10.

[11] The evaporation is carried out at a temperature lower than 85 °C, the intermediate acephate potassium composition contains 1 wppb to 33 wppm of acetoacetamide, and the purified acephate potassium composition contains less than 33 wppm of acetoacetamide. The method according to [4].

[12] The method according to

[11] , wherein the intermediate acephate potassium composition further contains less than 33 wppm of acetoacetamide-N-sulfonic acid.

[13] The evaporation is carried out at a temperature lower than 60 °C, the residence time in the evaporator is less than 50 minutes, the intermediate acephate potassium composition contains 10 wppb to 25 wppm of acetoacetamide, and the purified acephate potassium composition contains 10 wppb to 15 wppm of acetoacetamide. The method according to [4].

[14] The method according to

[13] , wherein the intermediate acephate potassium composition contains less than 30 wppm of acetoacetamide-N-sulfonic acid.

[15] The evaporation is carried out at a temperature in the range of 20 °C to 55 °C, the residence time in the evaporator is in the range of 1 minute to 300 minutes, the separation is carried out at a temperature in the range of -10 °C to 15 °C, the residence time of the separation operation is in the range of 1 to 180 minutes, the crude acephate potassium composition contains 500 wppm to 2375 wppm of acetoacetamide, the intermediate acephate potassium composition contains 10 wppb to 20 wppm of acetoacetamide and 10 wppb to 20 wppm of acetoacetamide-N-sulfonic acid, and the purified acephate potassium composition contains 10 wppb to 10 wppm of acetoacetamide and 1 wppb to 20 wppm of acetoacetamide-N-sulfonic acid. The method according to [4].

[16] (i) The evaporation is carried out at a temperature lower than 46 °C; (ii) the residence time in the evaporator is less than 30 minutes; (iii) the crystallization is carried out at a temperature lower than 35 °C; (iv) the intermediate potassium acesulfame composition contains 10 wppb to 12 wppm of acetoacetamide; and (v) the purified potassium acesulfame composition contains 10 wppb to 7 wppm of acetoacetamide, the method according to [4].

[17] the method according to

[16] , wherein the intermediate potassium acesulfame composition contains less than 20 wppm of acetoacetamide-N-sulfonic acid.

[18] the method according to [4], wherein the crude potassium acesulfame composition further contains a solvent, and the method further comprises removing the solvent from the crude potassium acesulfame composition before the evaporation.

[19] the method according to [1], wherein the weight percentage of acetoacetamide in the purified potassium acesulfame composition is lower than the weight percentage of acetoacetamide in the crude potassium acesulfame composition.

[20] separating a transfer phase containing at least 2% by weight of acetoacetamide from the acesulfame-H composition to form a purified acesulfame-H composition; the method according to [2], further comprising this.

[21] the method according to

[20] , wherein the neutralization comprises neutralizing the acesulfame-H in the purified acesulfame-H composition to form the crude potassium acesulfame composition containing potassium acesulfame and acetoacetamide.

[22] the method according to [1], wherein the concentration comprises evaporating the crude potassium acesulfame composition to form a water stream and an intermediate potassium acesulfame composition containing potassium acesulfame and less than 50% by weight of water, the separation comprises crystallizing the intermediate potassium acesulfame composition to form a crystal-containing stream containing potassium acesulfame crystals, and filtering the crystal-containing stream to form the purified potassium acesulfame composition.

[23] the method according to

[22] , wherein the filtration comprises at least two filtration operations. A purified acetosulfame potassium composition produced by the method described in

[24] [1].

[25] A method for producing a purified acetosulfame potassium composition, comprising: (a) reacting sulfamic acid with triethylamine to form an amidosulfamate; (b) reacting the amidosulfamate with diketene to form an acetoacetamide salt; (c) contacting dichloromethane with sulfur trioxide to form a cyclizing agent composition; (d) reacting the acetoacetamide salt with sulfur trioxide in the cyclizing agent composition to form a cyclic sulfur trioxide adduct; (e) hydrolyzing the cyclic sulfur trioxide adduct to form an acetosulfame-H composition; (f) neutralizing the acetosulfame-H to form a crude acetosulfame potassium composition containing acetosulfame potassium and acetoacetamide; (g) evaporating the crude acetosulfame potassium composition to form a water stream and an intermediate acetosulfame potassium composition containing acetosulfame potassium and less than 75% by weight of water; (h) crystallizing the intermediate acetosulfame potassium composition to form acetosulfame potassium crystals; and (i) filtering the acetosulfame potassium crystals to form a purified acetosulfame potassium composition containing acetosulfame potassium and less than 10 wppm of acetoacetamide; ; wherein the evaporation is carried out at a temperature lower than 50 °C and the residence time in the evaporator is less than 30 minutes.

[26] The method according to

[25] , wherein the filtration is carried out at a temperature lower than 35 °C and the crystallization is carried out at a temperature lower than 35 °C.

[27] A purified acetosulfame potassium composition produced by the method according to

[25] .

[28] An acetosulfame potassium composition containing acetosulfame potassium and less than 33 wppm, preferably less than 10 wppm of acetoacetamide. The potassium acesulfame composition according to

[28] , further comprising acetoacetamide-N-sulfonic acid of less than 33 wppm, preferably less than 10 wppm.

[30] The potassium acesulfame composition according to

[28] , further comprising 0.001 wppm to 5 wppm of organic impurities and / or 0.001 wppm to 5 wppm of at least one heavy metal.

[31] The potassium acesulfame composition according to

[30] , wherein the at least one heavy metal is selected from the group consisting of mercury, lead, and mixtures thereof.

[32] The potassium acesulfame composition according to

[31] , wherein the mercury is present in an amount of 1 wppb to 20 wppm.

[33] The potassium acesulfame composition according to

[31] , wherein the lead is present in an amount of 1 wppb to 25 wppm.

Claims

1. 1. A method for producing a purified acesulfame potassium composition, comprising: (a) providing a crude acesulfame potassium composition comprising acesulfame potassium, acetoacetamide, and water; (b) concentrating the crude acesulfame potassium composition to form an intermediate acesulfame potassium composition comprising acesulfame potassium and less than 75% by weight water, and a water stream; (c) separating the intermediate acesulfame potassium composition to form the purified acesulfame potassium composition comprising acesulfame potassium and less than 33 wppm acetoacetamide, wherein the weight percent of acetoacetamide in the purified acesulfame potassium composition is lower than the weight percent of acetoacetamide in the crude acesulfame potassium composition; Including; The above process, wherein the concentrating step (b) is carried out at a temperature below 85° C. and the separating step (c) is carried out at a temperature below 20° C.

2. The preparing step (a) reacting a sulfamic acid with an amine to form an amidosulfamate; reacting said amidosulfamate salt with an acetoacetylating agent to form an acetoacetamide salt; reacting the acetoacetamide salt with a cyclizing agent in a cyclizing agent composition to form a cyclic sulfur trioxide adduct; hydrolyzing the cyclic sulfur trioxide adduct to form an acesulfame-H composition comprising acesulfame-H; and neutralizing the acesulfame-H in the acesulfame-H composition to form the crude acesulfame potassium composition. The method of claim 1 , comprising:

3. 2. The method of claim 1, wherein the intermediate acesulfame potassium composition contains less than 33 wppm acetoacetamide-N-sulfonic acid.

4. 2. The method of claim 1, wherein said concentrating comprises evaporating said crude acesulfame potassium composition to form a water stream and said intermediate acesulfame potassium composition.

5. 5. The method of claim 4, wherein the evaporation residence time is less than 180 minutes.

6. 6. The method of claim 5, wherein the intermediate acesulfame potassium composition contains less than 33 wppm acetoacetamide-N-sulfonic acid.

7. The separation comprises: crystallizing the intermediate acesulfame potassium composition to form acesulfame potassium crystals; and The acesulfame potassium crystals are filtered to obtain the purified acesulfame potassium composition. To form; The method of claim 4 , comprising:

8. 8. The method of claim 7, wherein the filtration is carried out at a temperature of 35° C. or less.

9. 8. The method of claim 7, wherein the crystallization is carried out at a temperature of 35° C. or less.

10. 8. The method of claim 7, wherein the crystallization is carried out at a pH below 10.

11. 5. The method of claim 4, wherein the evaporation is conducted at a temperature below 85° C., the intermediate acesulfame potassium composition contains from 1 wppb to 33 wppm acetoacetamide, and the purified acesulfame potassium composition contains less than 33 wppm acetoacetamide.

12. 12. The method of claim 11, wherein the intermediate acesulfame potassium composition further comprises less than 33 wppm acetoacetamide-N-sulfonic acid.

13. 5. The method of claim 4, wherein the evaporation is conducted at a temperature below 60° C., the evaporation residence time is less than 50 minutes, the intermediate acesulfame potassium composition comprises from 10 wppb to 25 wppm acetoacetamide, and the purified acesulfame potassium composition comprises from 10 wppb to 15 wppm acetoacetamide.

14. 14. The method of claim 13, wherein the intermediate acesulfame potassium composition contains less than 30 wppm acetoacetamide-N-sulfonic acid.

15. 5. The method of claim 4, wherein said evaporation is conducted at a temperature in the range of 20° C. to 55° C., said evaporation residence time is in the range of 1 minute to 300 minutes, said separation is conducted at a temperature in the range of −10° C. to 15° C., said separation operation residence time is in the range of 1 minute to 180 minutes, said crude acesulfame potassium composition comprises 500 wppm to 2375 wppm acetoacetamide, said intermediate acesulfame potassium composition comprises 10 wppb to 20 wppm acetoacetamide and 10 wppb to 20 wppm acetoacetamide-N-sulfonic acid, and said purified acesulfame potassium composition comprises 10 wppb to 10 wppm acetoacetamide and 1 wppb to 20 wppm acetoacetamide-N-sulfonic acid.

16. (i) the evaporation is carried out at a temperature below 46°C; (ii) the evaporation residence time is less than 30 minutes; (iii) the crystallization is carried out at a temperature below 35° C.; (iv) the intermediate acesulfame potassium composition comprises 10 wppb to 12 wppm acetoacetamide; and (v) The method of claim 4, wherein the purified acesulfame potassium composition contains from 10 wppb to 7 wppm acetoacetamide.

17. 17. The method of claim 16, wherein the intermediate acesulfame potassium composition contains less than 20 wppm acetoacetamide-N-sulfonic acid.

18. 5. The method of claim 4, wherein the crude acesulfame potassium composition further comprises a solvent, and the method further comprises removing the solvent from the crude acesulfame potassium composition prior to the evaporation.

19. separating a transition phase comprising at least 2% by weight of acetoacetamide from said acesulfame-H composition to form a purified acesulfame-H composition; The method of claim 2 further comprising:

20. The neutralization removes the acesulfame-H in the purified acesulfame-H composition.

20. The method of claim 19, comprising neutralizing to form said crude acesulfame potassium composition comprising acesulfame potassium and acetoacetamide.

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