JP2826637B2 - Method for producing 2-acrylamide-2-methylpropanesulfonic acid - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing high-purity 2-acrylamido-2-methylpropanesulfonic acid.

Prior art and its problems 2-Acrylamido-2-methylpropanesulfonic acid (hereinafter abbreviated as AMS) and its homologues are used to improve the dyeability of acrylic fibers and the like by copolymerizing with acrylic monomers. Have been.

AMS and homologues or copolymers of the homologues of AMS are extremely excellent as a polymer electrolyte, and are used as a flocculant, a dispersant, a thickener, an anti-power failure agent and the like (US Pat. No. 2,983,712). No. 3,332,904).
In addition, AMS and its homologs are also used in water-absorbing polymers and the like.

Conventionally, many methods have been proposed for the production of AMS.
As a typical example, an excess of acrylonitrile is used as a reaction solvent and a reaction raw material, and fuming sulfuric acid and isobutene are supplied therein and reacted, and a small amount of water is added to the obtained mixture to precipitate. A method of collecting the precipitate of AMS by filtration (Japanese Patent Publication No. 50-30059, etc.) and the like.

This method is excellent as an industrial production method, but the reaction product has a yellow color because the acrylonitrile polymer and its sulfate are by-produced, and its AMS purity is low. Requires sophisticated purification steps such as recrystallization. Therefore, by mixing acrylonitrile and fuming sulfuric acid during the production process at a temperature of 0 ° C. or less, preferably at a temperature of −10 ° C., contamination of the resulting AMS impurities and yellowish coloring can be avoided to some extent. Is unsuitable for industrial production due to the need for low temperatures, and the purity of the obtained AMS is still insufficient.

Further, in the above method, when the production scale is to be increased, the quality and yield of the obtained AMS tend to be further reduced, and the burden on the purification step is further increased.

Means for Solving the Problems An object of the present invention is to provide a method for solving the problems of the conventional method and obtaining AMS with high purity and high yield.

That is, the present invention relates to a method for producing 2-acrylamido-2-methylpropanesulfonic acid by reacting acrylonitrile, concentrated sulfuric acid or fuming sulfuric acid, and isobutene; a) Formula IR ₁ -NH-R ₂ I [formula Wherein R ₁ and R ₂ are the same or different and represent hydrogen, an amino group, an alkyl group, an alkyl group having an amino group as a substituent, an aryl group, or a phenyl lower alkyl group. Or an acid addition salt thereof, b) a compound of the formula II Wherein R ₁ ′ represents an amino group, a methylamino group, an ethylamino group, a phenylamino group or a dimethylamino group;
R ₂ has the same meaning as above. R ₁ and R ₂ may combine with each other to form a group —CH ₂ CH ₂ —NH—. R ₃ represents hydrogen, a lower alkyl group, a hydroxyl group or a group —N ＝ C (CH ₃ ) ₂ . Y represents an oxygen atom or a sulfur atom. And c) at least one of sodium sulfite, sodium bisulfite, sodium thiosulfate, sodium hydrosulfite, potassium sulfite, potassium bisulfite, potassium thiosulfate and potassium hydrosulfite. A method for producing 2-acrylamido-2-methylpropanesulfonic acid, characterized in that the reaction is carried out by adding at least one selected from reducing inorganic compounds that are It is related.

The present inventor repeated many experiments to achieve the above object, and as a result, the above a), b) and c) were added to the AMS synthesis reaction system.
AMS having high whiteness and high purity by allowing the reaction to proceed in the presence of at least one specific additive selected from
Was obtained in good yield. Further, according to the study of the present inventors, it has been found that when a compatibilizing agent is added together with the above-mentioned specific additive, the AMS purity and yield obtained can be further improved. The present invention has been completed based on these findings.

The concentrated sulfuric acid used in the present invention may have a concentration of about 80% or more, more preferably 98% or more, and the fuming sulfuric acid may have a sulfur trioxide concentration of about 2 to 30%. Concentrated sulfuric acid or fuming sulfuric acid can be used in an amount of 0.9 to 1.4 times equivalent to isobutene. Acrylonitrile can be used in an excess amount because the unreacted one functions as a reaction solvent.
The equivalent is preferably 20 times equivalent, preferably 5 to 10 times equivalent.

In the present invention, a) a compound represented by Formula I or an acid addition salt thereof, b) a compound represented by Formula II or an acid addition salt thereof, or c) a predetermined reducing inorganic compound is added to the above three-component reaction system. It is essential that the reaction be allowed to proceed by addition.

Specific examples of the compound represented by the formula I or its acid addition salt (a) include, for example, ammonia, methylamine, dimethylamine, ethylamine, diethylamine, n-propylamine, di-n-propylamine, i-propyl Amine, di-i-propylamine, n-butylamine, i
-Butylamine, sec-butylamine, i-butylamine, di-n-butylamine, di-i-butylamine, n
-Amylamine, pentamethylenediamine, n-hexylamine, hexamethylenediamine, n-octylamine, 1,8-diaminooctane, n-decylamine, 1,10
-Alkylamines such as diaminodecane, cyclohexylamine, aniline, N-methylaniline, benzylamine, N-methylbenzylamine, phenylethylamine, arylamines such as diphenylamine, hydrazine, methylhydrazine, N, N-dimethylhydrazine, phenylhydrazine, etc. And the hydrochloride or sulfate of the above compound.

Specific examples of the compound represented by the formula II or the acid addition salt thereof (b) include, for example, urea, thiourea, N-methylurea, 1,1-dimethylurea, 1,3-dimethylurea, N-ethyl Urea, 1,1-diethyl urea, 1,3-diethyl urea, ethylene urea, N-phenyl urea, 1,3-diphenyl urea,
Carbamoyl compounds such as semicarbazide or its hydrochloride or sulfate, acetone semicarbazone, hydroxyurea, tetramethylurea and the like can be mentioned.

Further, as the reducing inorganic compound (c), sodium sulfite, sodium hydrogen sulfite, sodium thiosulfate,
At least one of sodium hydrosulfite, potassium sulfite, potassium hydrogen sulfite, potassium thiosulfate and potassium hydrosulfite is used.

The above-mentioned additives a) to c) may be used alone or in combination of two or more, and the mixing ratio may be 0.1% by weight or more based on the amount of acrylonitrile in the reaction system. It is better to be 3.0% by weight.

In the present invention, when a compatibilizer is used in combination with the above additives, AMS can be obtained with higher purity and higher yield. As such a compatibilizer, a non-aqueous polar solvent that is soluble in the reaction system itself and dissolves the additive is effective, and specifically, tetrahydrofuran, 1,4-dioxane, N, N-
Dimethylformamide, dimethylsulfoxide, acetic acid,
It is preferable to use acetic anhydride, an aliphatic carboxylic acid having 1 to 5 carbon atoms or an anhydride thereof. The optimum type and amount of the compatibilizer are appropriately selected according to the type of the additive before the combination is used. The mixing ratio of the compatibilizing agent is also appropriately selected, but it is usually preferable to be about 0.3 to 10% by weight based on the amount of acrylonitrile in the reaction system.

The addition of the additive and the compatibilizer is not particularly limited.For example, the additive and the compatibilizer may be dissolved after mixing acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid. It is desirable to dissolve in acrylonitrile and / or concentrated sulfuric acid or fuming sulfuric acid before mixing. Of course, the additive may be dissolved in acrylonitrile in advance, the compatibilizer may be dissolved in concentrated sulfuric acid or fuming sulfuric acid, or the compatibilizer may be dissolved in acrylonitrile and the additive may be dissolved in concentrated sulfuric acid or fuming sulfuric acid. Dissolution is about 50
It is preferable to carry out at a temperature of not more than ℃, usually at room temperature.

In carrying out the method of the present invention, for example, acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid in which an additive and a compatibilizer are dissolved in advance as described above are first mixed. In the mixing, in the conventional method, it is necessary to perform at a temperature of −10 ° C. or less for suppressing a side reaction, but in the present invention, the mixing can be performed at an easy operation temperature of 15 ° C. or less, preferably about 0 to 10 ° C. . Gaseous isobutene is blown into the mixture at a temperature of about 20 to 50 ° C. with stirring to cause a reaction. If necessary, a small amount of water is added, the precipitated product is filtered, further washed with acrylonitrile, and dried to obtain AMS. The reaction time, stirring, and other conditions are not particularly limited, and may be performed under appropriate conditions according to a known method.

According to the inventor's research, each raw material is continuously supplied,
It has been found that when the present invention is practiced by employing a continuous method of continuously removing the product, the purity and yield of the obtained AMS are further improved. Therefore, according to the present invention, acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid are supplied at a constant speed to continuously mix them, and then isobutene is supplied to the mixture at a constant speed to continuously react to produce 2-acrylamide. -2-
In producing methyl propane sulfonic acid continuously,
a) Formula I R ₁ —NH—R ₂ I wherein R ₁ and R ₂ are the same or different and each represents hydrogen, an amino group, an alkyl group, an alkyl group having an amino group as a substituent, an aryl group, or a phenyl group; Shows a lower alkyl group. Or an acid addition salt thereof, b) a compound of the formula II Wherein R ₁ ′ represents an amino group, a methylamino group, an ethylamino group, a phenylamino group or a dimethylamino group;
R ₂ has the same meaning as above. R ₁ and R ₂ may combine with each other to form a group —CH ₂ CH ₂ —NH—. R ₃ represents hydrogen, a lower alkyl group, a hydroxyl group or a group —N ＝ C (CH ₃ ) ₂ . Y represents an oxygen atom or a sulfur atom. And c) at least one of sodium sulfite, sodium bisulfite, sodium thiosulfate, sodium hydrosulfite, potassium sulfite, potassium bisulfite, potassium thiosulfate and potassium hydrosulfite A continuous production method of 2-acrylamido-2-methylpropanesulfonic acid, characterized by continuously adding at least one selected from reducible inorganic compounds and a compatibilizer as needed to the reaction system. Include.

The above-mentioned continuous method of the present invention is schematically shown as an example of the first method.
This will be described with reference to the drawings. The apparatus shown in the figure comprises a container 1 containing acrylonitrile and a container 2 containing concentrated sulfuric acid or fuming sulfuric acid. Each of the containers 1 and 2 is mixed by means of feed pipes 1 'and 2' via metering pumps 3 and 4, respectively. 5
Linked to In the illustrated apparatus, the mixer 5 is a static mixer, but is not limited thereto, and may be, for example, a mixer having a stirrer. The mixer 5 is connected to a reactor 6 having an isobutene introduction pipe 13 and a stirring device such as a multistage impeller. The reactor 6 is connected to a buffer container 7 and circulates the reaction mixture via another circulation pump 8 and a heat exchanger 9 while taking out an amount of the reaction mixture corresponding to the raw material supply amount. Reference numeral 10 denotes a crystal filter provided with a crystal take-out port 11 and a filtrate take-out valve 12, which performs solid-liquid separation of the reaction mixture from the buffer vessel 7.

First, acrylonitrile is supplied to the mixer 5 at a constant speed using the pump 3. At the same time, concentrated sulfuric acid or fuming sulfuric acid is supplied to the mixer 5 by the pump 4 at a constant speed. At this time, the additive and the compatibilizer are separately added in advance to acrylonitrile and one or both of concentrated sulfuric acid and fuming sulfuric acid. The supply rates of acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid can be arbitrarily selected and are not limited, but under preferable operating conditions, the former supply rate is usually in the range of 25 to 120 kg / h, preferably 50 to 69 kg / h, and Is preferably 5 to 20 kg / h, more preferably 9 to 11 kg / h. The two supplied to the mixer 5 are mixed at a temperature of about 20 ° C. or lower, preferably 5 to 10 ° C. by cooling, for example, with ice water, and then supplied to the reactor 6. While circulating this mixture using a pump 8, isobutene gas is supplied from a supply pipe 13 provided at the bottom of the reactor in the reactor 6. The feed rate of isobutene can be determined according to the feed rate of acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid, but is usually in the range of 3 to 12 kg / h, preferably in the range of 5 to 7 kg / h. React quickly. On this occasion,
For example, while maintaining the temperature at 30-60 ° C using cooling water, about 20
Preferably, the reaction is consumed within minutes. At the same time as the start of the reaction, the reaction-completed slurry liquid in an amount commensurate with the supply amount of the raw materials is continuously taken out and filtered with a crystal filter 10.
Taken from 12. The crystals separated by the crystal filter 10 are washed with acrylonitrile if necessary, and then dried to obtain high-purity AM.
Obtain S crystal.

Effect of the Invention As described above, the method of the present invention is advantageous for industrial production because acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid can be mixed at a relatively high temperature.

The AMS obtained by the method of the present invention has a white color without exhibiting a yellow color unlike a conventional product, and has a much paler yellow color and a substantially white color even when colored, even if colored. It has a high purity of about 90% or more, does not require special purification for ordinary use, and has a high yield.

As described above, according to the method of the present invention, AMS having extremely high quality and high purity can be stably obtained as compared with the conventional method.

Examples Hereinafter, the present invention will be described in more detail with reference to Examples. still,
In each of the examples, the addition ratio means a percentage represented by the weight of acrylonitrile used.

Example 1 Dry acrylonitrile in one glass reactor equipped with stirrer, dropping funnel, thermometer and gas injection tube
300 g (5.65 mol) were charged, and 3.0 g (addition rate 1%) of semicarbazide and 9.0 g (addition rate 1.0%) of acetic anhydride were added, followed by stirring at room temperature for 30 minutes.

The internal temperature was cooled to 0 ° C, and 7% fuming sulfuric acid (93% sulfuric acid) was stirred.
%, 7% of sulfur trioxide) was dropped and mixed while maintaining the internal temperature at 0 to 10 ° C over 30 minutes from the dropping funnel.

59.6 g (1.06 mol) of isobutene gas was blown into this mixed solution at an internal temperature of 30 to 40 ° C. over 1 hour, and then the mixture was left stirring at this temperature for 1 hour.

After adding 2.0 g of water to the reaction-terminated liquid and cooling to an internal temperature of 20 ° C., the resulting crystals were collected by filtration. Further, it was washed with acrylonitrile and dried to obtain 186.6 g of white AMS crystals.

The purity of the obtained AMS was 94.7%, and the yield was 85% based on isobutene.

Examples 2 to 13 AMS crystals were obtained in the same manner as in Example 1 except that the additives and compatibilizers were changed to the conditions shown in Table 1. Table 1 shows the results.

Comparative Example 1 In Example 1, acrylonitrile, fuming sulfuric acid and internal temperature were obtained without using semicarbazide and acetic anhydride.
The same operation was performed except that the mixture was added dropwise while maintaining the temperature at 15 to -10 ° C, to obtain 180.0 g of AMS crystals.

The obtained AMS is yellow, and its purity is 82.9%
Met. The yield was 82% based on isobutene.

Example 14 Using the apparatus shown in FIG. 1, the continuous method of the present invention was carried out as follows.

Dried acrylonitrile was put in the container 1, and acetic anhydride was added thereto to be 0.75% by weight and dissolved. Container 2
Was added with 7% fuming sulfuric acid, and urea was added and dissolved therein to 1.55% by weight. The acrylonitrile solution was supplied to the mixer 5 using the pump 3 at a rate of 60 kg / h. Simultaneously, the fuming sulfuric acid solution was supplied to the mixer 5 using the pump 4 at a rate of 10.9 kg / h. After the two supplied to the mixer 5, the jacket is cooled with ice water and mixed at an internal temperature of 8 to 10 ° C., and then filled into the reactor 6, the buffer vessel 7, the circulation pump 8 and the heat exchanger 9. Was. At this time, the operation of the pumps 3 and 4 is temporarily stopped, the stirring of the reactor 6 and the buffer container 7 and the operation of the pump 8 are started, the raw materials of the reaction system are circulated, and the internal temperature of the reactor 6 is reduced to 40. Isobutene gas was blown in at a rate of 6.5 kg / h from the bottom of the reactor while maintaining the temperature at 4545 ° C. 20 minutes after the start of isobutene gas supply,
The operation of the pumps 3 and 4 is started again to continuously supply acrylonitrile, concentrated sulfuric acid or fuming sulfuric acid to continue the reaction. At the same time, the reaction-completed slurry liquid in an amount corresponding to the supply amount of the raw material is continuously dropped into the crystal filter 10 through the overflow pipe at the top of the buffer vessel 7 and filtered. The filtrate is taken out from the pulp 12 and acrylonitrile is distilled. Collected. Crystal filter
The crystals separated in step 10 were washed with acrylonitrile and dried to obtain AMS crystals.

The resulting AMS was white and its purity was 99, 3%.

Example 15 In Example 14, the acetic anhydride in the container 1 was replaced with glacial acetic acid, dissolved in acrylonitrile so that the blending ratio became 1.5% by weight, and a stirrer was used instead of the mixer 5 in FIG. AMS crystals were obtained in the same manner except that a mixer having the following formula was used.

The resulting AMS was white and its purity was 99, 4%.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an example of an apparatus for carrying out the continuous method of the present invention. DESCRIPTION OF SYMBOLS 1 ... Acrylonitrile accommodation container 1 '... Acrylonitrile supply tube 2 ... Concentrated sulfuric acid or fuming sulfuric acid accommodation container 2' ... Concentrated sulfuric acid or fuming sulfuric acid supply tube 3 ... Measuring pump 4 ... Measuring pump 5 ... Mixer 6 … Reactor 7… Buffer vessel 8… Circulation pump 9… Heat exchanger 10… Filter 11… Crystal outlet 12… Valve 13… Isobutene supply pipe

Continuation of front page (56) References JP-A-2-96559 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07C 309 / 15,303 / 06

Claims (2)

(57) [Claims] Acrylonitrile, concentrated sulfuric acid or fuming sulfuric acid,
And isobutene to give 2-acrylamide-2-
In producing methylpropanesulfonic acid, a) a compound represented by the formula I R ₁ -NH-R ₂ I wherein R ₁ and R ₂ are the same or different and are hydrogen, an amino group, an alkyl group, an amino group as a substituent, Represents an alkyl group, an aryl group, or a phenyl lower alkyl group. Or an acid addition salt thereof, b) a compound of the formula II Wherein R ₁ ′ represents an amino group, a methylamino group, an ethylamino group, a phenylamino group or a dimethylamino group;
R ₂ has the same meaning as above. R ₁ ′ and R ₂ may combine with each other to form a group —CH ₂ CH ₂ —NH—. R ₃ represents hydrogen, a lower alkyl group, a hydroxyl group or a group —N ＝ C (CH ₃ ) ₂ . Y represents an oxygen atom or a sulfur atom. And c) at least one of sodium sulfite, sodium bisulfite, sodium thiosulfate, sodium hydrosulfite, potassium sulfite, potassium bisulfite, potassium thiosulfate and potassium hydrosulfite A method for producing 2-acrylamido-2-methylpropanesulfonic acid, characterized in that the reaction is carried out by adding at least one selected from the group consisting of reducing inorganic compounds and, if necessary, a compatibilizer to the reaction system. 2. Acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid are supplied at a constant speed to continuously mix them, and then isobutene is supplied to the mixture at a constant speed to continuously react to give 2-acrylamide. In the continuous production of 2-methylpropanesulfonic acid, a) a compound of the formula I R ₁ —NH—R ₂ I, wherein R ₁ and R ₂ are the same or different and are hydrogen, amino group, alkyl group, It represents an alkyl group having an amino group, an aryl group, or a phenyl lower alkyl group as a substituent. Or an acid addition salt thereof, b) a compound of the formula II Wherein R ₁ ′ represents an amino group, a methylamino group, an ethylamino group, a phenylamino group or a dimethylamino group;
R ₂ has the same meaning as above. R ₁ ′ and R ₂ may combine with each other to form a group —CH ₂ CH ₂ —NH—. R ₃ represents hydrogen, a lower alkyl group, a hydroxyl group or a group —N ＝ C (CH ₃ ) ₂ . Y represents an oxygen atom or a sulfur atom. And c) at least one of sodium sulfite, sodium bisulfite, sodium thiosulfate, sodium hydrosulfite, potassium sulfite, potassium bisulfite, potassium thiosulfate and potassium hydrosulfite A method for continuously producing 2-acrylamido-2-methylpropanesulfonic acid, characterized by continuously adding at least one selected from the group consisting of reducing inorganic compounds and, if necessary, a compatibilizer to the reaction system.