JPH0377860A - Purification of 2-acylamido-2-methylpropanesulfonic acid - Google Patents

Abstract

PURPOSE:To purify 2-acrylamido-2-methylpropanesulfonic acid (AMS) useful for improving dyeability of fibers, etc., and as a polymer electrolyte, etc., by extracting AMS with concentrated acetic acid in the presence of a specific stabilizer in a hot state. CONSTITUTION:Crude AMS is extracted with concentrated acetic acid, preferably glacial acetic acid as an extraction solvent at >=80 deg.C to purify AMS. One or more compounds selected from a compound shown by the formula R1-NH-R2 (R1 and R2 are H, amino, alkyl, amino-substituted alkyl, aryl or phenyl lower alkyl) or a salt thereof, a compound shown by the formula (R1 and R2 are shown as mentioned above or bonded to form CH2CH2-NH; R3 is H, lower alkyl, OH, etc.; Y is O or S) or an acid addition salt thereof and calcium or barium salt of an inorganic acid or organic acid are used as the stabilizer and the amount of the stabilizer used is 0.2-5 pts.wt. based on 100 pts.wt. AMS.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a purification method for obtaining 2-acrylamido-2-methylpropanesulfonic acid with high purity and high yield.

BACKGROUND ART Conventionally, many methods have been proposed for producing 2-acrylamido-2-methylpropanesulfonic acid (hereinafter abbreviated as AMS).

A representative example of this is No. 17, in which excess acrylonitrile was used both as a reaction solvent and a reaction raw material, and in which fuming sulfuric acid and isobutyne were reacted, and a small amount of water was added to the resulting mixture to precipitate No. 17. Examples include a method of collecting AMS precipitates by filtration (Japanese Patent Publication No. 30059/1983, etc.).

AMS and its analogues are copolymerized with acrylic monomers and used to improve the dyeability of acrylic fibers and the like. In addition, homopolymers or copolymers of AMS and its homologs are extremely excellent as polymer electrolytes, and are used as flocculants, dispersants, thickeners, power outage prevention agents, etc. (U.S. Pat. No. 2,983,712) In addition, AMS and its analogues are also used in water-absorbing polymers and the like.

Among these uses, AMS produced by the above method
The crude crystals can be used as they are, but in applications that require high quality such as fibers, it is not possible to obtain high molecular weight homopolymers or copolymers when using the crude crystals. It is necessary to use highly purified AMS.

As a method for purifying AMS, it is not sufficient to simply wash the crude crystals of AMS with a solvent such as acrylonitrile. Therefore, a purification method of recrystallizing using methanol or aqueous acetic acid (British Patent No. 1090779, Japanese Patent Publication No.
0-30059, JP-A-53-13897, JP-A-54-163524, US Pat. No. 3,506,707, etc.).

However, the AMS solution or slurry is unstable to heat, and due to the heating during the recrystallization, the AMS
], there is a major drawback in that 6% of the polymer is lost through polymerization or decomposition.

In addition, when recrystallizing, about 50% of AMS is lost in the solvent, so it is necessary to repeat the recrystallization with the filtrate, but in this case, there is a disadvantage that the purity of AMS decreases. be. Moreover, the purity of the purified product obtained is insufficient, and it is extremely difficult to obtain AMS with a purity of 95% or higher.

Means for Solving the Problems The present invention solves the problems of the prior art as described above and improves the AMS.
The object of the present invention is to provide a method for purifying AMS with high purity and high yield.

That is, in purifying 2-acrylamido-2-methylpropanesulfonic acid, the present invention provides a) formula R1-NH-R2I where R1 and R2 are the same or different and hydrogen, amino group, alkyl represents an alkyl group, an aryl group, or a phenyl lower alkyl group having an amino group as a substituent. ] or an acid addition salt thereof, b) Formula ■E where R1 and R7 have the same meanings as above aR
l and R2 are bonded to each other to form a group -CH2CH2N H-
may be formed.

R1 is hydrogen, lower alkyl group, hydroxyl group or group -N-
=C(CH3)2. Y represents an oxygen atom or a sulfur atom. ] or an acid addition salt thereof; and C) hot extraction using concentrated acetic acid as an extraction solvent in the presence of at least 11 kinds of stabilizers selected from calcium salts or barium salts of inorganic acids or organic acids. The present invention relates to a method for purifying 2-acrylamido-2-methylpropanesulfonic acid, which comprises performing the following steps.

According to the inventor's research, j bipeds a), b) and C)
When extracting AMS using concentrated acetic acid, glacial acetic acid (7) or glacial acetic acid as an extraction solvent in the presence of a specific stabilizing compound selected from In addition, since concentrated acetic acid, which has low solubility of AMS at room temperature, is used, high purity A can be obtained without loss due to dissolution of AMS.
It has been found that MS can be efficiently obtained with high yield.

The present invention was completed based on this new knowledge.

The concentrated acetic acid used in the present invention is preferably one with a high concentration that has low solubility in AMS at room temperature, preferably 95% or more, more preferably 97% or more, and it is particularly preferable to use glacial acetic acid. Most preferred. By using such concentrated acetic acid, loss of AMS due to dissolution can be substantially prevented.

The amount of acetic acid used in the method of the present invention may be the same amount to an excess amount relative to the crude AMS, and more preferably about 300 to 800 parts by weight relative to 100 parts by weight of AMS in the crude AMS.

Compounds used as stabilizers in the present invention include:
a) Compound represented by formula I or its acid addition salt, b) Formula ■
The compounds represented by or acid addition salts thereof, and C) calcium salts or barium salts of inorganic or organic acids are included.

Specific examples of the compound represented by formula I or its acid addition salt (a) include ammonia, methylamine, dimethylamine, ethylamine, diethylamine, n-propylamine, di-n-propylamine, i-propyl amine, di-propylamine, n-butylamine, i,
-butylamine, 5ee-butylamine, i-butylamine, di-n-butylamine, di-me-butylamine,
Alkylamines such as n-amylamine, pentamethylenediamine, n-hexylamine, hexamethylenediamine, n-octylamine, 1,8-diaminooctane, n-decylamine, 1,10-diaminodecane, cyclohexylamine, aniline, N -Arylamines such as methylaniline, benzylamine, N-methylbenzylamine, phenethylamine, diphenylamine, hydrazine compounds such as hydrazine, methylhydrazine, N,N-dimethylhydrazine, phenylhydrazine, hydrochlorides or sulfates of the above compounds, etc. Can be mentioned.

Specific examples of the compound represented by formula (2) or its acid addition salt (b) include urea, thiourea, N-methylurea,
1,1-dimethylurea, 1,3-dimethylurea, N-ethylurea, 1.16-diethylurea, 1.3-diethylurea, ethyleneurea, N-phenylurea, 1,3-diphenylurea, formamide, N-methylformamide,
N,N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, formanilide,
Acetamide, N-methylacetamide, N,N-dimethylacetamide, N-ethylacetamide, N,N-
Examples include carbamoyl compounds such as diethylacetamide, benzamide, phenylacetamide, acetanilide, propionamide, semicarbazide or its hydrochloride or sulfate, acetone semicarbazone, hydroxyurea, and tetramethylurea.

In addition, examples of the calcium salt or barium salt (C) of an inorganic or organic acid include calcium chloride, calcium acetate, calcium nitrate, calcium nitrite, calcium bromide, calcium formate, barium chloride, barium acetate, barium nitrate, Examples include barium nitrate, barium bromide, barium formate, and the like.

The above stabilizers may be used alone or in combination of two or more. Further, the stabilizer may be added in a small amount to the crude AMS, more preferably 10% of the AMS in the crude AMS.
It is preferable to use about 0.2 to 5 parts by weight relative to 0 parts by weight.

The method of the present invention includes, for example, crude AMS produced by mixing excess acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid 12, blowing gaseous isobutyne into this mixture under stirring, and adding a small amount of water if necessary. It can be applied to all crude AMS produced by the known method. Particularly suitable crude AMS for carrying out the present invention is AMS obtained by proceeding the reaction in the above-mentioned known AMS production method in the presence of additives and, if necessary, a compatibilizer, which form the reaction system. The method using such additives and, if necessary, a compatibilizer is a method developed by the present inventor, and is 1.0% lower than the conventional method. AMS of high purity is obtained, and by purifying this according to the present invention, it becomes possible to obtain AMS of extremely high purity.

In the above method, the additive and 1. Now, the compound represented by formula 1 or its acid addition salt (a) used in the purification method of the present invention and the compound represented by formula 2 or its acid addition salt (a)
b) is used. Moreover, reducing inorganic compounds can be used instead of these. These additives can be used alone or in combination of two or more. Compounds a) and b) and 1- are the same as those exemplified above,
The above reducing inorganic compounds and 17 include, for example, sodium sulfite, sodium hydrogen sulfite, sodium thiosulfate, hydrosulfite! - Examples include storium, potassium sulfite, potassium hydrogen sulfite, potassium thiosulfate, potassium hydrozulfite, etc.

The blending ratio of the additive is preferably 0.1 to 3.0% by weight, preferably 0.1 to 3.0% by weight, based on the amount of acrylonitrile in the reaction system. and 17,
Non-aqueous polar solvents that are soluble in the reaction system themselves and can dissolve additives are effective; specifically, tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, dimethyl sulfoxide, acetic acid, anhydrous Acetic acid, aliphatic carboxylic acids having 1 to 5 carbon atoms, or their anhydrides, etc. can be used, but they are selected as appropriate depending on the type of additive used, and the blending ratio thereof is also selected as appropriate, but usually the reaction system The amount of I7 is preferably about 0.3 to 10.0% by weight based on the amount of acrylonitrile in the composition. Known conditions can be used as they are for the AMS production reaction conditions (i.e., additives and, if necessary, a compatibilizer are added to and dissolved in acrylonitrile and one or both of concentrated sulfuric acid and fuming sulfuric acid, and then the two are mixed. It is sufficient to supply isobutyne to this and react at a temperature of about 20 to 50°C.The mixing of acrylonitrile and concentrated sulfuric acid or fuming sulfuric acid must be carried out by the conventional method by cooling to below 0°C. However, by using additives, it is possible to mix at a temperature of about 1.5°C or lower, particularly 0 to 10°C, which is more advantageous than the conventional method.

In the purification method of the present invention, crude AMS produced by a known method or the above method discovered by the present inventor is hot extracted with concentrated acetic acid in the presence of the stabilizers a) to C) above, and then, Cool to room temperature and collect crystals by filtration, wash with acetic acid if necessary and dry to obtain purified AMS.

The extraction temperature in the method of the present invention is preferably about 80°C or higher, more preferably in the range of 90 to 100°C.

In addition, the extraction time is appropriately selected depending on the extraction conditions such as the concentration of acetic acid, the type of stabilizer, and their blending ratio.
Normally, about 80 minutes is sufficient.

In this method, acetic acid contained in the filtrate after filtering the crystals is recovered by simple distillation.1. It can be reused and is economical.

Effects of the Invention In the method of the present invention, AMS has an improvement of 1. compared to the conventional method.
It can be obtained with extremely high purity and high yield, and can be suitably used in various applications, and can be used to expand its applications.

Example The present invention will be explained in more detail with reference to Examples below.

In addition, for each hit, the addition rate of the stabilizer is the addition weight expressed as a percentage of the weight of AMS in the input AMS crude crystals, and the alteration loss rate of AMS is the addition rate of the stabilizer added as a percentage of the weight of AMS in the input AMS crude crystals. It means the difference between the weight of AMS in the crystals and the weight of the total detected AMS after extraction, expressed as a percentage of AMS17) polymerization in the input AMS crude crystals.

Reference Example (Production of AMS Crude Crystals) 360 g of dried acrylonitrile and 3 mL of urea were placed in a reactor equipped with a stirrer, a dropping funnel, a thermometer, and a gas blowing tube.
．． 6g of acetic anhydride and 10g of acetic anhydride were charged and stirred at room temperature for 30 minutes.While stirring, the internal temperature was cooled to 0°C (7), and 0% fuming sulfuric acid (
97.2 g of sulfuric acid (90% sulfuric acid, 1.0% sulfur trioxide) was added dropwise and mixed from the dropping port -1 over 30 minutes while maintaining the internal temperature at 0 = 10°C.

Add 62.5g of isobutine gas to this mixture at an internal temperature of 30~
Bubbling was carried out at 40° C. for 1 hour, and the mixture was left stirring at this temperature for 1 hour.

Add 2 Og of water to the reaction completed solution and cool to an internal temperature of 20°C (
Later, the produced crystals were collected by filtration (2. Washed with acrylonitrile and dried to obtain 3 g of white AMS crude crystals 18).

The yield of AMS obtained was 86.7% based on fuming sulfuric acid,
Purity was 95.2%.

Example〕.

A M S crude crystal 1 obtained in the above reference example was placed in a glass reactor Q (equipped with a stirrer, a cooling reflux device, and a thermometer).
50.0 g and 750 g of 98% glacial acetic acid were charged, and urea was further added at an addition rate of 3%.

Stir this slurry 1. After heating to 100° C. and extracting at this temperature for 1 hour, the mixture was cooled to room temperature. The crystals were collected by filtration, washed with 50 ml of glacial acetic acid, and then dried.

The AMS crystals obtained were white, and the yield was 143.7
g (yield rate 95.8%). The purity of this AMS was 98.2% and its degradation loss was 0.6%.

Examples 2 to 11 and Comparative Examples] In Example 1, the stabilizer and extraction temperature and time were changed to those shown in Table 1, and the extraction and treatment were carried out according to the conditions. The results are shown in Table 1.

Claims (1)

[Claims] [1] In purifying 2-acrylamido-2-methylpropanesulfonic acid, a) formula IR_1-NH-R_2 [wherein R_1 and R_2 are the same or different, 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 its acid addition salt, b
) Formula II ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R_1 and R_2 have the same meanings as above. R_1 and R_2 bond to each other to form a group -CH_2CH_
2-NH- may also be formed. R_3 is hydrogen, lower alkyl group, hydroxyl group, or group -N
=C(CH_3)_2 is shown. Y represents an oxygen atom or a sulfur atom. ] or an acid addition salt thereof, and c) hot extraction using concentrated acetic acid as an extraction solvent in the presence of at least one stabilizer selected from calcium salts or barium salts of inorganic acids or organic acids. A method for purifying 2-acrylamido-2-methylpropanesulfonic acid, the method comprising: