JPH04356453A - Production of methacrylsulfonate - Google Patents

Abstract

PURPOSE:To efficiently produce a high-purity methacrylsulfonate in high yield. CONSTITUTION:(1) An aqueous solution of a methacrylsulfonate obtained by sulfonating isobutylene and then neutralizing is crystallized by cooling to precipitate seed crystal of the methacrylsulfonate, (2) the aqueous solution containing the seed crystal is crystallized by cooling to precipitate crystal of the methacrylsulfonate, (3) an aqueous solution containing the precipitated crystal of the methacrylsulfonate is subjected to solid-liquid separation into crystal and mother liquor and (4) at least the mother liquor is partially concentrated, circulated to the process (2) and joined to the aqueous solution containing the seed crystal before the crystallization by cooling to give the methacrylsulfonate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing methallyl sulfonate. More specifically, the present invention relates to a method for efficiently producing methallyl sulfonate with high purity and high yield.

0002

[Prior Art] Japanese Patent Publication No. 48-35249 describes N.
, N-dialkyl-substituted carbonamides, N-acyl-azacycloalkanes, N-alkyl-substituted lactams, tetraalkylureas, N,N'-carbonylbis-azacycloalkanes, and N,N'-dialkyl-2-imidazolidi Methallylsulfonic acid obtained by reacting an addition compound of sulfur trioxide and a complex former selected from the group consisting of non-containing compounds with isobutylene in a water-immiscible inert halogen alkane at a temperature of -20 to +60°C. A method is disclosed in which the solution is neutralized with aqueous base and optionally concentrated under reduced pressure or spray dried to isolate the methallyl sulfonate.

[0003] Japanese Patent Publication No. 46-41527 discloses that isobutylene is mixed with sulfur trioxide and aliphatic carboxylic acid N,N
- a complex with an amide compound selected from the group consisting of dialkyl-substituted amides and N-alkyl-substituted lactams, and the reaction is carried out at a temperature of -20 to +60°C in a reaction solvent consisting of an excess of said amide compound; using at least 1 mole of isobutylene to sulfur trioxide, and then the resulting methallylsulfonic acid solution was neutralized with a basic compound selected from the group consisting of organic bases and inorganic bases, and the obtained A method for concentrating a neutralized solution under reduced pressure is disclosed.

JP-A No. 49-43926 discloses a lower aliphatic amide compound selected from the group consisting of sulfur trioxide and N,N-dialkyl-substituted amides of aliphatic carboxylic acids or N-alkyl-substituted lactams. An invention is disclosed that relates to a method for producing methallyl sulfonate using a halogenated hydrocarbon solution.

JP-A-63-51368 discloses that a complex of sulfur trioxide and dimethylacetamide is formed in dichloromethane, then isobutylene is quickly added and mixed to react, and the reaction product is then neutralized with a base. A method for producing methallyl sulfonate is disclosed.

Furthermore, JP-A-63-88167 discloses that isobutylene and a sulfur trioxide/dimethylacetamide complex are reacted in dichloromethane, and the resulting reaction mixture is neutralized with an aqueous alkali solution to produce methallylsulfonic acid. In a method for producing a salt, (a) dichloromethane is distilled off from the reaction mixture prior to the neutralization step, and (b) dimethyl containing 25% by weight or more of methallylsulfonate is then neutralized with an alkaline aqueous solution. While preparing an acetamide/water mixed slurry, (c) heating the mixed slurry to 40 to 120°C to dissolve the methallyl sulfonate, and (d) subsequently cooling it to crystallize the methallyl sulfonate. A method for analysis is disclosed.

[0007] In the above method, that is, in the production of methallyl sulfonate by direct sulfonation of isobutylene, △1 monosulfonate, △2 disulfonate, hydroxysulfonate, Glauber's salt, etc. are produced as by-products. It is known.

The produced methallyl sulfonate is generally obtained by cooling and crystallizing the reaction aqueous solution and then performing solid-liquid separation from the aqueous solution containing the precipitated methallyl sulfonate crystals. In addition, the solid-liquid separated mother liquor is a saturated solution of methallyl sulfonate, and in order to increase the yield of methallyl sulfonate, it is mixed with the new reaction aqueous solution that produced methallyl sulfonate and cooled again. It is desirable to circulate it in crystallization.

[0009] However, by-products accumulate in the mother liquor obtained by solid-liquid separation of methallyl sulfonate as it circulates. Therefore, the crystals of methallyl sulfonate obtained by cooling crystallization from the mixed liquid of the circulating mother liquor of solid-liquid separation and the new reaction liquid have a high content of by-products due to the attached moisture. will increase, and the by-product will remain as an impurity in the methallyl sulfonate.

0010

SUMMARY OF THE INVENTION An object of the present invention is to provide a new method for producing methallylsulfonate. Another object of the present invention is to provide a method for efficiently producing methallylsulfonate with high purity and high yield. Further objects and advantages of the present invention will become apparent from the description below.

[0011]

[Means for Solving the Problems] According to the present invention, the above objects and advantages of the present invention are as follows: (1) An aqueous solution of methallyl sulfonate obtained by sulfonating and then neutralizing isobutylene is subjected to cooling crystallization. (2) subjecting the aqueous solution containing the seed crystals to cooling crystallization to precipitate crystals of methallyl sulfonate; (3) methallyl sulfonate crystals; The aqueous solution containing the precipitated crystals is subjected to solid-liquid separation to separate the crystals and mother liquor, and (4) at least a part of the mother liquor is concentrated and then circulated to the above step (2) for cooling before crystallization. This is achieved by a method for producing methallylsulfonate, which is characterized in that it is combined with an aqueous solution containing seed crystals.

The method for producing methallyl sulfonate by sulfonation of isobutylene in step (1) of the present invention is as follows:
Conventionally known methods are not particularly limited. Generally, isobutylene is sulfonated with sulfur trioxide and a suitable complex forming agent in a solvent, and then neutralized. As this complex forming agent, for example, amide compounds such as dimethylacetamide and dimethylformamide, dioxane, etc. are used. Examples of solvents include methylene chloride, ethylene chloride, trichloroethylene,
Among lower aliphatic halogenated hydrocarbons such as chloroform, carbon tetrachloride, trichloroethane, and tetrachloroethylene, dichloromethane is particularly preferably used. In addition, examples of alkaline aqueous solutions include, for example, alkali metal hydroxides,
Aqueous solutions of bicarbonates and carbonates, especially sodium or potassium hydroxides, bicarbonates and carbonates, are used.

[0013] Such a complex of sulfur trioxide used in the sulfonation reaction of isobutylene is prepared with a complex forming agent in a solvent that is generally 10 times or more, particularly 15 times or more (weight ratio) to the sulfur trioxide. It is preferable that the slurry solution is continuously subjected to the sulfonation reaction of isobutylene as it is, thereby making it possible to produce methallylsulfonic acid with less by-products such as Δ2disulfonic acid. In addition, the amount of isobutylene used is preferably 1.5 mol or more per 1 mol of sulfur trioxide in order to suppress the formation of by-products, and it is particularly preferable to maintain the amount of isobutylene at 2 to 3 mol depending on the amount of isobutylene recycled. practical in relation to its scale. In addition, in the sulfonation reaction, when the reaction temperature becomes higher than 40°C, by-products increase, so it is generally preferable to maintain the reaction temperature at 5 to 30°C.

In general, a method (continuous method) in which a slurry solution containing a sulfur trioxide complex and isobutylene are simultaneously added to a reactor at a fixed molar ratio and mixed to form a sulfonate,
Since homogeneous mixing in a short period of time is insufficient, excess or deficiency of isobutylene occurs in the reactor, and various by-products are likely to be produced in addition to methallylsulfonic acid. Therefore, in this method of continuously sulfonating isobutylene, a slurry solution containing sulfur trioxide/dimethylacetamide complex is introduced from the middle part of the reactor, and isobutylene is dispersed and blown into the reactor from the lower part to make it uniform. By mixing, the formation of by-products such as Δ2 disulfonate can be significantly reduced.

In addition, in the above-mentioned isobutylene sulfonation reaction, removing as much water from the reaction system as possible suppresses the formation of by-products and obtains highly pure methallyl sulfonate. desirable for. In such sulfonation of isobutylene, in order to maintain the reaction system in a state where it is substantially free of water, it is first necessary to remove the water contained in the raw materials, reaction solvent, etc. and entrained. be. That is, the raw materials, isobutylene, sulfur trioxide, complex forming agents such as dimethylacetamide, and reaction solvents, such as chlorinated hydrocarbons, may be used as necessary.
Desiccants such as tetraphosphorus decaoxide, sodium perchlorate, aluminum oxide (activated alumina), silica gel, synthetic zeolite (molecular sieve), calcium chloride,
Or use a dryer to remove the moisture, generally 10p.
It is desirable to pre-treat to below pm.

[0016] Furthermore, in order to prevent moisture from entering or absorbing moisture from the outside air (atmospheric air), these raw materials, complex forming agents, and reaction solvents are used in a closed system using storage tanks, transfer piping, and other equipment. It is preferable. Furthermore, equipment such as the reactor for sulfonating isobutylene and the aging tank for the reaction solution should be kept closed, such as by using a top cover or sealed with dry nitrogen, to prevent moisture from entering from the outside air as much as possible. It is desirable to avoid this. Therefore, in the process of sulfonating isobutylene of the present invention, it is recommended that both the sulfur trioxide/dimethylacetamide complex generation step and the isobutylene sulfonation reaction step be performed in a continuous manner, which inevitably requires equipment. Since a closed system is formed, contamination of moisture from the outside air is avoided.

Next, the reaction solution obtained by sulfonating isobutylene is heated to about 50°C as necessary and generally heated to 15°C.
After ripening for a residence time of 1 minute or more and removing excess isobutylene by distillation, an aqueous alkali solution is added to neutralize in a conventional manner to produce methallyl sulfonate. This neutralized solution undergoes phase separation into an aqueous solution containing methallyl sulfonate and an organic solution containing dimethylacetamide and chlorinated hydrocarbons. Therefore, dimethylacetamide and chlorinated hydrocarbons can be recovered from this organic solution by distillation, and each can be reused. On the other hand, an aqueous solution of methallyl sulfonate is generally extracted by using the same type of chlorinated hydrocarbon as that used as the reaction solvent as an extractant, preferably in a multistage extraction column.
The remaining dimethylacetamide can be removed to an extremely small amount.

Next, in step (1), the aqueous solution of methallyl sulfonate is concentrated to a predetermined concentration by stripping the solvent if necessary, and then cooled to form seed crystals of methallyl sulfonate. is precipitated in advance. In other words, as in the conventional method, a mother liquor obtained by solid-liquid separation of methallyl sulfonate in the subsequent process is circulated and mixed with the resulting aqueous solution of methallyl sulfonate, that is, an aqueous solution without seed crystals, and then cooled. When subjected to crystallization, the amount of water adhering to the cake (solid substance) of methallyl sulfonate obtained by solid-liquid separation is generally 10% by weight or more, so it is necessary to circulate according to the amount of water. This results in by-products accumulated in the mother liquor remaining in the methallylsulfonate cake. Moreover, since by-products remain firmly inside the crystals and cakes of such methallyl sulfonate, the removal effect by water washing is not sufficiently exerted.

On the other hand, in the present invention, as described above, in step (1), the reaction aqueous solution of the newly generated methallyl sulfonate is cooled and crystallized in advance to precipitate seed crystals. The aqueous reaction solution containing the crystals is mixed with the circulating mother liquor of solid-liquid separation, and in step (2), the mixed solution is subjected to main crystallization in the presence of seed crystals to obtain the obtained methallyl sulfonate. The amount of water adhering to the cake is small, and as a result, the amount of residual by-products can be reduced. In addition, crystals of methallyl sulfonate precipitated by preliminary crystallization serve as seed crystals and grow into large crystals in the next main crystallization. Therefore, the obtained crystals of methallyl sulfonate and its cake have little residual by-products inside them, and can be easily removed by washing with water. In such preliminary crystallization of step (1) of the present invention, crystals of methallyl sulfonate are added to the reaction aqueous solution in the following main crystallization step (
It is sufficient to crystallize a necessary amount as a seed crystal in step (2)), and it can generally be obtained at a crystallization temperature of 60 to 70°C. In addition, in the main crystallization step of the present invention, the desired methallyl sulfonate may be crystallized according to conventional methods, and the crystallization temperature is generally 0 to 25°C, preferably 5 to 15°C. used.

A typical and preferred example of the method for producing methallyl sulfonate of the present invention is shown in the figure by a block diagram of each step. First, step (a) of forming a complex with sulfur trioxide using dimethylacetamide as a complex forming agent in a methylene chloride solvent, then step (b) of introducing isobutylene and sulfonation to produce methallylsulfonic acid, and recovery and aging step of isobutylene. After that, a step of neutralizing with an aqueous solution of caustic soda to produce sodium methallylsulfonate (SMS), a step of separating the two-phase separated solvent phase of methylene chloride to recover dimethylacetamide, and a step of separating the other one. A step of recovering dimethyl acetamide by solvent extraction of methylene chloride from an aqueous solution containing the SMS, a step of stripping methylene chloride from the aqueous solution of SMS with water vapor, a step of heating and concentrating, and then cooling and crystallizing. A preliminary crystallization step, a main crystallization step, a step of solid-liquid separation of precipitated SMS crystals using a centrifuge, a step of washing the SMS cake with water, and a drying step to prepare the SMS product. get.

[0021] In order to economically recover the SMS discharged into the liquid, the solid-liquid separated mother liquor is circulated to the crystallization step.
It is also preferable that the aqueous solution used to wash the SMS cake is also recycled to the concentration step. Further, the circulating separated mother liquor may be concentrated in advance and subjected to hot filtration, if necessary, and a portion may be discharged as waste liquid.

[0022]

[Function and Effects] Furthermore, according to the present invention, the amount of water adhering to the cake (solid material) obtained by centrifuging the precipitated crystals of methallyl sulfonate is surprisingly small to 10% by weight or less; Accordingly, results with less residual by-products can be obtained. Furthermore, it is advantageous to be able to reduce the amount of water adhering to such a cake of methallyl sulfonate because it can reduce the load in the subsequent drying step. Furthermore, the cake of methallyl sulfonate subjected to solid-liquid separation according to the present invention is recognized to have high cleaning efficiency for by-products deposited by a saturated solution of methallyl sulfonate. The effect of providing the preliminary crystallization step in the present invention is that crystals (seeds) with a small content of preliminary crystallized by-products grow in the main crystallization, and metalyl sulfone consisting of large crystals is produced. This is presumed to be because it is obtained as an acid salt cake. That is, since by-products of methallyl sulfonate, which have strong hygroscopic properties, are not included in the crystals, the amount of adhering moisture in the cake is reduced, and as a result, the amount of by-products remaining due to the adhering moisture is also reduced.

[0023]

EXAMPLES Examples of the present invention will be shown below together with comparative examples, but the present invention is not limited to these examples. Example 1 According to the method for producing methallyl sulfonate shown in Figure 1,
14.7 kg/H of methylene chloride as a reaction solvent as a raw material,
Dimethylacetamide 1.38kg/H, sulfur trioxide 0
．． The sulfonation of isobutylene was carried out continuously with a feed rate of 80 kg/H and a feed rate of 1.8 kg/H of isobutylene. That is, first, dimethylacetamide is added to a reaction solvent of methylene chloride, and then sulfur trioxide is introduced thereto to produce a sulfur trioxide/dimethylacetamide complex in the form of a slurry, and then in a sulfonation reactor, sulfur trioxide/dimethylacetamide is added. The sulfonation reaction was carried out while simultaneously blowing in a slurry solution of dimethylacetamide complex and isobutylene. The sulfonation reaction is carried out using a cylindrical reactor equipped with a stirrer.
A slurry solution of sulfur trioxide/dimethylacetamide complex was introduced from the middle part, and at the same time, isobutylene was introduced from the lower part through a ring-shaped dispersion nozzle provided in the center.

[0024] For each raw material, commercially available products in drums or cylinders are used. Methylene chloride is dried with calcium chloride to reduce the water content to 10 ppm or less, dimethylacetamide is dried with a molecular sieve to reduce the water content to 10 ppm or less, Sulfur trioxide was removed by distillation to remove sulfuric acid, and isobutylene was dried using a molecular sieve to reduce the water content to 10 ppm or less. Note that the supply piping, the complex generation step (apparatus), and the sulfonation reaction step (apparatus) were all kept in a closed system. Next, the reaction liquid extracted from the upper part of the sulfonation reactor was heated to 55°C with a heater, and then placed in an aging tank at 0.
．． It was left to stand for 3 hours. Next, the reaction solution was neutralized with an aqueous solution of caustic soda, and then methylene chloride and dimethylacetamide were separated, and an aqueous solution (temperature: 100
°C) was obtained.

[0025]

[Table 1]

[0026] The reaction aqueous solution was cooled to a temperature of 70°C in the pre-crystallization step to obtain a solution in which seed crystals of methallylsulfonate were precipitated. Next, in the main crystallization step, the solution in which the crystals were precipitated and the mother liquor obtained by solid-liquid separation of the methallyl sulfonate were concentrated and hot-filtered to form the solution shown in Table 2 below.
The same weight of the circulating fluid (temperature: 100°C) having the composition shown was mixed.

[0027]

[Table 2]

Further, the above mixed liquid was cooled to a predetermined crystallization temperature shown in Table 3, and main crystallization was carried out. The resulting slurry containing crystals of methallyl sulfonate was heated to a diameter of 1
After solid-liquid separation using a centrifuge with a 0 cm basket and a rotation speed of 5000 rpm, the moisture content of the cake was measured by the Karl Fischer method, and impurity components were analyzed by liquid chromatography and potentiometric titration. The results are shown in Table 3.

[0029]

[Table 3]

Example 2 In Example 1, the circulating fluid heated to a temperature of 100°C was mixed with the solution in which seed crystals of methallylsulfonate were precipitated at a cooling temperature of 70°C, and then the solution was heated to a predetermined temperature in the same manner. The main crystallization was carried out at cooling temperature. The results obtained are shown in Table 4.

[0031]

[Table 4]

Example 3 In Example 1, the temperature for preliminary crystallization of the reaction aqueous solution was changed to 60°C.
It was carried out in exactly the same manner except that it was cooled to ℃. The results are shown in Table 5.

[0033]

[Table 5]

Comparative Example 1 The reaction aqueous solution in Example 1 was subjected to 1 without pre-crystallization.
It was carried out in exactly the same manner except that the mixture was mixed at a temperature of 00°C. The results are shown in Table 6.

[0035]

[Table 6]

[Brief explanation of drawings]

FIG. 1 is a block diagram showing each step of a typical manufacturing method of the present invention.

[Explanation of sign] B. Complex formation step B Sulfonation process C. Isobutylene recovery and aging process D. Neutralization process E Two-phase separation process F Extraction process G Stripping process H. Concentration process Preliminary crystallization process Nu　Main crystallization process Solid-liquid separation process E Cake cleaning process Wa　Drying process

Claims (1)

[Claims] Claim 1: (1) an aqueous solution of methallyl sulfonate obtained by sulfonating and then neutralizing isobutylene is subjected to cooling crystallization to precipitate seed crystals of methallyl sulfonate; (2) seed crystals of methallyl sulfonate are precipitated; The aqueous solution containing the crystals is subjected to cooling crystallization to precipitate crystals of methallyl sulfonate, (
3) The aqueous solution containing precipitated crystals of methallyl sulfonate is subjected to solid-liquid separation to separate the crystals and mother liquor, and (4
) After concentrating at least a portion of the mother liquor, the above step (2)
A method for producing methallyl sulfonate, characterized in that it is mixed with an aqueous solution containing seed crystals before being cooled and crystallized.