JPH0710824B2 - Method for producing methallyl sulfonate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a methallyl sulfonate, more specifically, after isobutylene is sulfonated with a sulfur trioxide / dimethylacetamide complex in a solvent of dichloromethane. The present invention relates to a method for producing a colorless and highly pure methallyl sulfonate by crystallizing a slurry obtained by neutralization.

[Prior art]

The methallyl sulfonate is widely used as a dyeing modifier for acrylic fibers, and industrially requires a high-purity product of 99.9% or more containing no impurities other than water.

Conventionally, as a method for synthesizing such a methallyl sulfonate, a method in which methallyl chloride and sodium sulfite are used as raw materials and these are subjected to a Strecker reaction is generally known.

However, this Strecker method requires advanced purification technology and complicated equipment for separating and refining inorganic salts such as sodium chloride, sodium sulfite, and sodium sulfate, which are present in a large amount in the reaction product, as an upper raw material. Since the methallyl chloride used is expensive, there is a drawback in that its manufacturing cost is high.

As a method for solving these drawbacks, a method has been proposed in which inexpensive isobutylene is used as a raw material and this is directly sulfonated with a complex of sulfur trioxide to synthesize a methallyl sulfonate.

For example, Japanese Examined Patent Publication (Kokoku) No. 48-35249 describes a complex compound obtained from a complex-forming agent such as N, N-dialkyl-substituted carbonamide and N-alkyl-substituted lactam and a stoichiometric amount of sulfur trioxide. The methallyl sulfonate was dissolved in an active halogen alkane, and then isobutylene was added to this solution for a long time (60 to 120 minutes), followed by reaction at a temperature of -20 to + 60 ° C, and then neutralization with a base. A method of manufacturing is disclosed.

Although this production method has the advantage that the amount of inorganic salts by-produced is small, a wide variety of undesirable side reactions occur,
By-products of various compounds with similar solubilities are formed. Moreover, since the expensive complex-forming agent used in the reaction is recovered by vacuum distillation or spray drying, it remains in the crystals of methallyl sulfonate or deteriorates due to heat history. Therefore, the yield of the methallyl sulfonate in the crystallization purification and the yield of the complex-forming agent are reduced, which is a disadvantage that it is not industrially advantageous.

〔Purpose〕

INDUSTRIAL APPLICABILITY The present invention overcomes the above-mentioned deficiencies of the prior art, can extremely suppress side reactions, and also obtains a highly pure methallyl sulfonate in a high yield with a very small amount of by-products with similar solubility. An object of the present invention is to provide an industrially advantageous method for producing a methallyl sulfonate.

〔Constitution〕

According to the present invention, a method for producing methallyl sulfonate by reacting isobutylene with a sulfur trioxide / dimethylacetamide complex in a dichloromethane solvent and neutralizing the obtained reaction mixture with an aqueous alkaline solution, ) Dichloromethane as a reaction solvent is distilled off from the reaction mixture prior to the neutralization step, and (b) is then neutralized with an alkaline aqueous solution to contain a dimethylacetamide / water mixed slurry containing 25% by weight or more of methallyl sulfonate. And (c) heating the mixed slurry to 40 to 120 ° C. to dissolve the methallyl sulfonate, and (d) subsequently cooling to crystallize the methallyl sulfonate. A method for producing a featured methallyl sulfonate is provided.

In general, the reaction of isobutylene and sulfur trioxide is known to produce various by-products via β-sultone of isobutylene as shown in the following reaction formula (JP-A-49- No. 36623, Japanese Patent Publication No. 53-47094).

That is, in the sulfonation reaction of isobutylene, hydroxysulfonic acid, Δ ₁ monosulfonic acid, disulfonic acid, and polymer sulfonic acid are by-produced in addition to the target methallyl sulfonic acid. Among these by-products, Δ ₁ monosulfonate and hydroxysulfonate, which have higher solubility than methallylsulfonate, can be separated relatively easily, but disulfone which has lower solubility than methallylsulfonate. Complete removal of acid salts and the like from the reaction mixture is extremely difficult.

The amount of these by-products, particularly disulfonic acid, is significantly affected by the types of the complex-forming agent and solvent used, as well as the reaction method and reaction conditions.

The present inventors have used dimethylacetamide as a complex-forming agent and dichloromethane as a solvent to react sulfur trioxide with a complex of dimethylacetamide and isobutylene,
(A) Dichloromethane as a reaction solvent and excess isobutylene are distilled off from the obtained reaction mixture prior to the neutralization step, and (b) then neutralized with an alkaline aqueous solution to give 25% by weight of methallyl sulfonate. A dimethylacetamide / water mixed slurry containing the above is prepared, and (c)
When a specific synthesis condition is selected in which the mixed slurry is heated to 40 to 120 ° C. to dissolve the methallyl sulfonate, and (d) is subsequently cooled to crystallize the methallyl sulfonate, , A high-purity methallyl sulfonate capable of extremely reducing the amount of by-products such as disulfonic acid, and having an excellent effect as an economically advantageous dyeing property modifier of acrylic fiber. The present invention has been completed and the present invention has been completed.

Next, the present invention will be described in more detail.

In the present invention, dimethylacetamide is used as a complex forming agent to form a sulfur trioxide complex. The amount of dimethylacetamide used with respect to sulfur trioxide significantly affects the amount of by-products such as disulfonic acid, and in the present invention, the smaller the amount of free dimethylacetamide, the more preferable the result is. It should be 1.0 to 2.0 mol, preferably 1.02 to 1.5 mol, per mol of sulfur.

The above complex can be obtained by adding sulfur trioxide to a mixed solution of dichloromethane and dimethylacetamide, which is a reaction solvent, and at this time, the amount of dimethylacetamide used is limited in order to suppress coloring and decomposition of dimethylacetamide. It should be 0.65 parts by weight or less to 1 part by weight of dichloromethane.

Further, the addition temperature of sulfur trioxide is 40 ° C. or lower, preferably in order to suppress coloring and decomposition of dimethylacetamide.
20 ℃ or less.

Further, after the addition of sulfur trioxide, it is desirable to further vigorously stir for about 10 to 30 minutes to complete the complex formation reaction.

Next, in the present invention, the sulfonation reaction of isobutylene is carried out in a solvent of dichloromethane using the complex of sulfur trioxide and dimethylacetamide.

The amount of dichloromethane used as the solvent in the present invention is
The amount is 5 parts by weight or more with respect to 1 part by weight of sulfur trioxide, and is preferably 7 to 20 parts by weight from the viewpoint of the effect of suppressing the amount of the by-produced disulfonate and the economy.

There is no particular limitation on the order of mixing the raw materials in this sulfonation reaction, and for example, a method of adding isobutylene to a dichloromethane solution of a sulfur trioxide / dimethylacetamide complex, or vice versa.
A method of adding a dichloromethane solution containing a dimethylacetamide complex, further isobutylene and sulfur trioxide.
Any method such as a method of continuously adding a dimethylacetamide complex solution with dichloromethane in a constant molar ratio can be employed.

The amount of isobutylene used is 1.5 per mol of sulfur trioxide.
From the viewpoint of the effect of suppressing by-products and economy, it is preferably 1.8 to 3.0 mol. The reaction temperature of this sulfonation reaction is 40 ° C or lower, preferably 5 to 30 ° C. If the temperature exceeds 40 ° C, the amount of by-products produced increases, which is not desirable. The reaction time is appropriately 5 to 90 minutes.

Subsequently, in the present invention, the remaining β-sultone in the reaction product is heated to isomerize to methallyl sulfonic acid. The isomerization temperature is 40-60 ° C. If it exceeds 60 ° C, methallylsulfonic acid deteriorates, which is not desirable. The reaction time is suitably 20 to 60 minutes.

When the sulfonation and isomerization reactions are complete, the reaction mixture obtained is first subjected to distillation, dichloromethane and unreacted isobutylene being distilled off from the reaction mixture.
At this time, the distillation temperature is 80 ° C. or lower, preferably 60 ° C. or lower in view of the stability of methallyl sulfonic acid.

In the present invention, by adopting a constitution in which dichloromethane and excess isobutylene are distilled off before the neutralization step,
Since it is possible to prevent water from being mixed into these components, dichloromethane and isobutylene can be reused without dehydration, and the amount of by-products such as mirabilite and hydroxysulfonic acid in the reaction mixture is small. Gives good results.

Next, the reaction mixture obtained by distilling dichloromethane and excess isobutylene was neutralized with an alkaline aqueous solution, and the methallyl sulfonate was added in an amount of 25% by weight or more (the saturated solubility of the methallyl sulfonate at room temperature was 25% by weight). A dimethylacetamide / water mixed slurry containing a) is prepared.

Examples of the alkali used when neutralizing the methallyl sulfonic acid include alkali metal hydroxides, bicarbonates and carbonates, but sodium and potassium hydroxides from the viewpoint of economy and versatility, Bicarbonates and carbonates are preferably used.

The concentration of the alkaline aqueous solution is 17% by weight or more, preferably 20 to 20 from the viewpoint of crystallization efficiency and economic efficiency of the methallyl sulfonate.
48% by weight.

Subsequently, in the present invention, the dimethylacetamide / water mixed slurry of methallyl sulfonate is heated to 40 to 120 ° C. to dissolve the precipitated methallyl sulfonate, and then cooled to perform crystallization. . The temperature during crystallization is 0 to 25 ° C.
From the viewpoint of crystallization efficiency and economy, the temperature is preferably 5 to 15 ° C.

Next, the dimethylacetamide / water mixed slurry containing the crystallized methallyl sulfonate is separated into the methallyl sulfonate and the mother liquor by centrifugation or suction filtration.
At this time, the filter cake is washed to remove the mother liquor containing dimethylacetamide and the side reaction product remaining in the filter cake. As the cleaning liquid, it is preferable to use a saturated aqueous solution of methallyl sulfonate in order to prevent reduction in yield due to dissolution of methallyl sulfonate. The amount of the saturated aqueous solution of methallyl sulfonate used is about the same as the weight of the filter cake.

If necessary, the filter cake may be subsequently washed with a solvent such as methanol or acetone to remove water to obtain high-purity methallylsulfonic acid.

In addition, the separated mother liquor is separated into methallylsulfonate and dimethylacetamide by centrifugation or suction filtration after distilling off water, but the former is returned to the neutralized slurry before crystallization, and the latter Dimethylacetamide is distilled and reused as a complexing agent.

〔effect〕

Since the present invention has the above-mentioned configuration, it has the following remarkable operational effects.

(1) Side reactions are suppressed and the amount of by-products with similar solubility can be extremely reduced, so it is possible to easily obtain a high-purity methallyl sulfonate of 99.9% or more by a purification operation such as crystallization. You can

(2) Since a methallyl sulfonate having an excellent color tone and odor can be obtained, decolorization and deodorization operations can be omitted.

(3) Equipment and process control can be simplified as compared with the method using the Strecker reaction.

(4) The dimethylacetamide is not thermally deteriorated, and the amount of residual dimethylacetamide in the filter cake is small because the methallylsulfonate is crystallized. Therefore, expensive dimethylacetamide can be recovered in high yield. Filterability (speed)
Is also good.

(5) Since the neutralized slurry is allowed to evaporate as it is after the temperature rise, it is not necessary to prepare or concentrate the eluate again.
Labor saving and fuel economy can be saved.

Therefore, the method for synthesizing the methallyl sulfonate of the present invention can easily obtain a high-purity methallyl sulfonate as compared with the conventional method, and thus the methallyl sulfonate of industrially extremely advantageous It can be called a manufacturing method.

〔Example〕

Next, the present invention will be described in more detail by way of examples. Quantitative analysis of methallyl sulfonate, Δ ₁ sulfonate and hydroxy sulfonate was performed using XL ・ 200FT-NMR (Varia
(manufactured by N. Co., Ltd.), and high performance liquid chromatograph LC-3A (manufactured by Shimadzu Corporation) was used for quantitative analysis of disulfonate.

Example 1 Dichloromethane (2500 g) and dimethylacetamide (300
Liquid sulfur trioxide (250 g) was added dropwise while stirring a mixture of g and 1.1 times mol of sulfur trioxide) at 5 ° C.

Next, the obtained sulfur trioxide / dimethylacetamide complex solution was charged into 4 autoclaves, and after nitrogen substitution, 300 mmH
liquid isobutylene (5 ℃, 350g,
2 times mol) was introduced for 30 seconds with respect to sulfur trioxide.

After reacting at a temperature of 15 to 30 ° C for 30 minutes, the temperature was raised to 45 ° C and the mixture was further stirred for 30 minutes.

After completion of the reaction, distillation was carried out to remove isobutylene and dichloromethane, followed by neutralization with a 20% by weight aqueous sodium hydroxide solution.

The above slurry was heated to 60 ° C. to make a transparent liquid, and then allowed to cool to room temperature with stirring.

After centrifuging the above crystallization slurry (5000 rpm, 10 minutes),
The filter cake was washed with 200 g of a saturated aqueous solution of sodium methallyl sulfonate. Subsequently, the properties of the filter cake dehydrated by centrifugation (5000 rpm, 10 minutes) were examined. The results are shown in Table-1.
Shown in.

Example 2 The sulfonation and isomerization reactions were carried out in the same manner as in Example 1,
A mixture of methallylsulfonic acid (400 g) from which dichloromethane and isobutylene were removed by distillation was prepared from the obtained reaction mixture and dimethylacetamide. The mother liquor by-produced in Example 1 was dehydrated under reduced pressure, 450 g of sodium methallyl sulfonate recovered by filtration and 130 g of water were added,
The mixture was neutralized with a 20% aqueous sodium hydroxide solution.

The high-concentration slurry was heated and dissolved, and the properties of the filter cake obtained by crystallization, centrifugal filtration, washing and dehydration according to Example 1 were examined. The results are shown in Table-1.

Example 3 A mixture of methallyl sulfonic acid (400 g) and dimethylacetamide prepared by carrying out sulfonation and isomerization reactions according to Example 1 and distilling off isobutylene and dichloromethane from the resulting reaction mixture. The mother liquor by-produced in 2 was dehydrated under reduced pressure, and sodium methallylsulfonate recovered by filtration and 130 g of water were added. This mixture was neutralized with a 20 wt% caustic soda aqueous solution and then dissolved by heating. Subsequently, according to Example 1, the properties of the filter cake that was washed and dehydrated after crystallization were examined. The results are shown in Table-1.

Comparative Example 1 The sulfonation and isomerization reactions were performed according to Example 1, and the obtained reaction mixture was directly neutralized with a 20 wt% caustic soda aqueous solution. Next, the same slurry containing 450 g of sodium methallyl sulfonate was placed in a topping flask, and after dichloromethane, water and dimethylacetamide were distilled off under a reduced pressure of 15 to 20 mmHg at an oil bath temperature of 98 ° C. for 2 hours, the residue was characterized. Examined. The results are shown in Table-1.

Claims (1)

[Claims] 1. A method for producing a methallyl sulfonate by reacting isobutylene with a sulfur trioxide / dimethylacetamide complex in a solvent of dichloromethane, and neutralizing the resulting reaction mixture with an aqueous alkali solution, wherein (a) Dichloromethane, which is a reaction solvent, is distilled off from the reaction mixture prior to the neutralization step. (B) Next, a dimethylacetamide / water mixed slurry containing 25% by weight or more of methallyl sulfonate is neutralized with an alkaline aqueous solution. Along with the preparation, (c) heating the mixed slurry to 40 to 120 ° C. to dissolve the methallyl sulfonate, and (d) subsequently cooling to crystallize the methallyl sulfonate. And a method for producing a methallyl sulfonate.