JP3407336B2 - Method for purifying aminoethanesulfonic acids - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to an alkali metal hydrochloride, 1,2-ethanedisulfonic acid alkali metal salt (hereinafter referred to as EDS alkali metal salt), which is synthesized from 1,2-dichloroethane and alkali metal sulfite. ) Or the like as an impurity, an unpurified β-chloroethanesulfonic acid alkali metal salt (hereinafter referred to as CES alkali metal salt) aqueous solution is used as a raw material, and this aqueous solution is ammonia or N-substituted amines (hereinafter, these are combined, Aminoethanesulfonic acid, or N, obtained by reacting with amines)
-A method for purifying a substituted aminoethanesulfonic acid (hereinafter collectively referred to as aminoethanesulfonic acids).

The aminoethanesulfonic acid obtained when the amine is ammonia is a drug substance called taurine. When methylaminoethanesulfonic acid obtained when the amine is methylamine is reacted with a fatty acid chloride or the like in the presence of an alkali metal hydroxide, an acylated product is obtained, and the acylated product is Igep.
It is a surfactant that has been known for a long time under the name of on T, and is used as an excellent amino acid-based detergent that is hard and water resistant and does not harm the human body.

[0003]

2. Description of the Related Art Conventionally, as a purification method of aminoethanesulfonic acid, (1) an extraction method using ethyl alcohol as a medium (Ind. & Eng. Chem., 39 906-9.
(1947)) (2) Crystallization method using water as a medium (German Patent 112254)
No. 0) is known.

The method (1) is carried out by using purified C
After sodium ES was reacted with a large excess of amines and excess amines were removed by distillation, hydrochloric acid was added to give aminoethanesulfonic acids as shown in the formula, and the aqueous solution was evaporated to dryness, and then a large amount of 95% was added. % Hot ethyl alcohol is added to extract aminoethane sulfonic acids, and the alcoholic aqueous solution from which the aminoethane sulfonic acids have been extracted is cooled to crystallize the aminoethane sulfones and to perform solid-liquid separation. This is a method of obtaining crystals.

ClC ₂ H ₄ SO ₃ Na + nRNH ₂ → RNHC ₂ H ₄ SO ₃ RNH ₃ + NaCl (R = hydrogen or hydrocarbon alkyl group, n =
15-20) RNHC ₂ H ₄ SO ₃ RNH ₃ + HCl → RNHC ₂ H ₄ SO ₃ H + RNH ₃ Cl (R is the same as above) When this method is adopted as a commercial purification method for aminoethanesulfonic acids, raw material CES sodium In order to obtain a high-purity product, it is not possible to obtain a high-purity product in a single operation because a salt purification process is required, a large amount of alcohol used as an extraction medium is recovered, and a purification process is required. The extraction operation has to be repeated.

[0006] Further, since solid substances containing salt and amine chloride as equimolar amounts are discharged as impurities, it is not preferable from the viewpoint of environmental protection to dispose of them, which is a complicated process such as a separation process. Become.

The method (2) is originally a method for purifying aminoethanesulfonic acids using isethionic acid as a raw material as shown in the formula, and removal of EDS alkali metal salt is not considered.

HOC ₂ H ₄ SO ₃ Na + n RNH ₂ → RNHC ₂ H ₄ SO ₃ Na + H ₂ O RNHC ₂ H ₄ SO ₃ Na + 1 / 2H ₂ SO ₄ → RNHC ₂ H ₄ SO ₃ H + 1 / 2Na ₂ SO ₄ (R and n Is the same as above) That is, the method is the same as the aqueous solution of aminoethanesulfonic acid sodium salt obtained by the formula, as shown in the formula, by adding a mineral acid such as sulfuric acid and hydrochloric acid to convert the aminoethanesulfonic acid to the aqueous solution. Is concentrated to partially crystallize a sodium salt of mineral acid such as Glauber's salt.
By cooling the filtrate obtained by solid-liquid separation at a temperature of ℃ or more to room temperature, the aminoethanesulfonic acids are partially crystallized, and the solid-liquid separation is a method of obtaining the crystals, Since the separated liquid still contains a large amount of aminoethanesulfonic acid, it is recovered and circulated.

As a result of the study by the present inventors, if the desalted filtrate was simply cooled as in the same method, in view of its dissolution equilibrium,
It was found that it is impossible to obtain high-purity aminoethanesulfonic acid, since a small amount of sodium salt of mineral acid crystallizes during the crystallization of aminoethanesulfonic acid.

Further, although EDS alkali metal salt is not contained as an impurity, in addition to ethylene glycol, as shown in German Patent No. 219,023, isethionic acid is used in the reaction of the formula. Since the salt has very poor reactivity, the reaction cannot be completed despite the reaction conditions under high temperature and high pressure.
The unreacted isethionate remains, and the reaction of the formula is not very selective, and the formed aminoethanesulfonate reacts with the isethionate, and the chemical formula RN (C ₂ H ₄ SO ₃ Na) ₂ ,
It includes aminoethanedisulfonate, aminotriethanesulfonate represented by N (C ₂ H ₄ SO ₃ Na) ₃ . Among these impurities, ethylene glycol, isethionic acid, etc. have a much higher solubility than aminoethanesulfonic acids, and they are accumulated in the separated liquid of crystals of aminoethanesulfonic acid, which gradually increases the viscosity and impairs the filterability. In order to prevent the above, the separated liquid must be released in a timely manner even though it contains a large amount of aminoethanesulfonic acid, which significantly reduces the yield of aminoethanesulfonic acid.

[0011]

DISCLOSURE OF THE INVENTION The object of the present invention is to prepare aminoethane synthesized from an unpurified CES alkali metal salt containing impurities such as alkali metal hydrochloride, alkali metal sulfate and EDS alkali metal salt as a raw material. It is intended to provide a method for purifying aminoethanesulfonic acids, which comprises using water as a medium for purifying sulfonic acids and obtaining highly pure aminoethanesulfonic acid crystals in high yield without releasing a recovered separated liquid.

[0012]

DISCLOSURE OF THE INVENTION The gist of the present invention is produced from 1,2-dichloroethane and an alkali metal sulfite or vinyl chloride and an alkali metal bisulfite which are commercially produced in large quantities at low cost. , Unpurified CES
This is a method for purifying aminoethanesulfonic acids obtained by reacting an alkali metal salt as a raw material with amines as shown in the formulas, and its details will be described below.

ClC ₂ H ₄ SO ₃ M + nRNH ₂ → RNHC ₂ H ₄ SO ₃ RNH ₃ + MCl RNHC ₂ H ₄ SO ₃ RNH ₃ + MOH → RNHC ₂ H ₄ SO ₃ M + RNH ₂ + H ₂ O RNHC ₂ H ₄ SO ₃ M + H ⁺ → RNHC ₂ H ₄ SO ₃ H + M ⁺ (R: hydrogen or an alkyl group consisting of a hydrocarbon, n =
Integer value of 2 or more, M = Na, alkali metal such as K, H ⁺
= Mineral acid such as HCl and H ₂ SO ₄ ) In the technique of the present invention,
The unpurified CES alkali metal salt aqueous solution used in the formula contains inorganic salts such as alkali metal hydrochloride and alkali metal sulfate as well as EDS alkali metal salt as impurities, and in the formula, a large excess amount of amines is contained. However, when the amine supply amount is small, aminodiethanesulfonic acid amine salts and aminotriethanesulfonic acid amine salts are by-produced by the side reaction of the formula (1).

RNHC ₂ H ₄ SO ₃ RNH ₃ + ClC ₂ H ₄ SO ₃ M + RNH ₂ → RN (C ₂ H ₄ SO ₃ RNH ₃ ) ₂ + MCl NH (C ₂ H ₄ SO ₃ NH ₄ ) ₂ + ClC ₂ H ₄ SO ₃ M + NH ₃ → N (C ₂ H ₄ SO ₃ NH ₄ ) ₃ + MCl (R and M are the same as above) Therefore, the aminoethanesulfonic acid aqueous solution obtained in the present invention contains a large amount of inorganic metal such as alkali metal hydrochloride. In addition to salts, a small amount of EDS alkali metal salts, aminodiethanesulfonic acids and aminotriethanesulfonic acids are contained as impurities. In the method of the present invention, first,
The aqueous solution obtained in the reaction of (1) is distilled, and the amines supplied in excess by the formula and liberated by the formula are separated and removed.

Next, the present inventors have found that the solubility of EDS alkali metal salt is temperature-dependent, and that the solubility thereof further decreases in the presence of inorganic salts such as alkali metal hydrochloride and alkali metal sulfate. However, they have found that the higher the concentration of the inorganic salt, the lower the solubility of the EDS alkali metal salt in the low temperature range, and have reached the present invention.

That is, as shown in the formula, pH = 4.5 to 7.0 is adjusted by adding a mineral acid such as hydrochloric acid or sulfuric acid to convert into aminoethanesulfonic acid, and this aqueous solution is treated under atmospheric pressure or The solution obtained by concentrating under reduced pressure to obtain a saturated solubility liquid thereof is cooled to room temperature or lower to crystallize an EDS alkali metal salt as an impurity, and a crystallized solid substance is removed by a solid-liquid separation method such as filtration. . Prior to this step, filtration may be carried out at an elevated temperature of 80 ° C., if necessary, in order to separate out the crystallized inorganic salt.

As described above, in order to selectively crystallize the EDS alkali metal salt without crystallizing the aminoethanesulfonic acid, in the aqueous solution part, the aminoethanesulfonic acid concentration is ≦ 38.5%, the inorganic salt is After concentrating in a saturated aqueous solution having a concentration of ≤17.5%, the temperature is below room temperature, preferably 20
After cooling to below 0 ° C and above 0 ° C, the EDS alkali metal salt is crystallized.

The aqueous solution from which the EDS alkali metal salt has been separated is concentrated again under atmospheric pressure or under reduced pressure. This time, inorganic salts such as alkali metal hydrochloride are partially crystallized in a high temperature range of 80 ° C. or higher, The crystallized inorganic salt is removed by solid-liquid separation by filtration under high temperature. To selectively crystallize the inorganic salt in an aqueous solution of aminoethanesulfonic acid without crystallizing it, in the aqueous solution portion, aminoethanesulfonic acid concentration ≧ 40%, inorganic salt concentration ≦ 17%,
Desirably aminoethane sulfonic acid concentration = 52.5-5
It is good to concentrate to 5% and inorganic salt concentration = 13.5 to 15%.

Next, 3.5% or more and 30% or less, preferably 3.8% or more and 5% or less of water of the separated liquid is added to the separated liquid from which inorganic salts have been partially removed, and then diluted. The diluted aqueous solution is cooled to room temperature, specifically about 20 ° C., the aminoethanesulfonic acids are partially crystallized, and the crystallized aminoethanesulfonic acids are obtained by solid-liquid separation by filtration at room temperature. It is a thing. Since the separated filtrate still contains a large amount of aminoethanesulfonic acid, it is recycled. The step of returning the separated filtrate is preferably mixed with an aqueous solution of an aminoethanesulfonic acid alkali metal salt from which amines have been removed according to the formula, but may be mixed with the aqueous solution after pH adjustment.

As described above, in the method of the present invention, the desalted filtrate is diluted in the crystallization step of aminoethanesulfonic acids in order to obtain a high purity product. That is, when the inorganic salt separation filtrate is cooled without being diluted with water, as described above, due to its dissolution equilibrium, a small amount of an inorganic salt such as an alkali metal hydrochloride is crystallized out together with the aminoethanesulfonic acid, and the filtration thereof is performed. No matter how much water the cake is washed with, the solubility of aminoethanesulfonic acids is extremely higher than that of the above-mentioned inorganic salts, and it is not possible to remove these inorganic salts by only dissolving the aminoethanesulfonic acids. Unable to obtain ethanesulfonic acids.

It is desirable to add 3.8 to 5.0% of the amount of the inorganic salt-separated filtrate as an addition ratio of such diluted water, and even if more water is added, high-purity aminoethane sulfonic acids are obtained. Although it can be obtained, the larger the amount of water added, the less the crystallized substance becomes, which is not desirable.

Further, in the separated filtrate of aminoethanesulfonic acids, by-produced aminodiethanesulfonic acids and aminotriethanesulfonic acids are accumulated according to the formula. According to the measurement experiment conducted by the present inventors, The solubility of these impurities is almost the same as that of aminoethanesulfonic acids, but the temperature dependence is extremely poor and becomes lower than that of aminoethanesulfonic acids in a high temperature range of about 60 ° C or higher.
When this is accumulated and the concentration is almost the same as that of aminoethanesulfonic acid, it partially crystallizes in the crystallization step of the inorganic salt and becomes in equilibrium, so that it is not mixed with aminoethanesulfonic acid. The inventors found out and completed the technique of the present invention.

[0023]

As is apparent from the above description, according to the present invention, (1) since unpurified CES is used as a raw material and is purified from an aqueous solution obtained by reacting this with amines, purification of the raw material CES is performed. The process can be omitted.

(2) Since water is used as a medium without using a special compound such as alcohol as a medium, the steps of collecting and purifying the medium are not required, and the energy required for them can be saved.

(3) The whole amount of the separated filtrate of aminoethanesulfonic acids can be recovered and circulated without releasing part of the filtrate,
High yields can be maintained without loss of aminoethanesulfonic acids.

[0026]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 1,2 dichloroethane, an unpurified aqueous solution of CES sodium salt produced from sodium sulfite, and liquefied methylamine were added to an aqueous solution obtained by adding caustic soda, and then free methylamine was added. PH removed by distillation = 12.
2650.0 g of the composition liquid shown in Table 1 of 4 was put in a 3 liter separable flask, and 250.2 g of 35% hydrochloric acid was added to adjust the pH to 6.0.

The flask was immersed in an oil bath, heated, and concentrated under reduced pressure of -440 mmHg.

When the amount of evaporated water reaches about 790 ml,
The liquid became cloudy due to the crystallized substance, but the concentration was further continued, and the concentration was stopped when the amount of evaporated water reached 1410 ml.

The amount of the concentrated liquid was 1484.9 g, and when the concentrated liquid was poured into a centrifugal filter which was kept warm by circulating warm water of about 85 ° C. through a jacket to perform solid-liquid separation, 1235.7.
g of filtrate was obtained. Since some solid matter adhered to the inner wall of the flask, about 10 g of water was added to dissolve the solid matter, and the aqueous solution was used for washing the centrifugal filter cake, and the centrifugal filter cake was washed with 27.4 g of fresh water. , 228.5 g of washed primary salt cake and 48.1 g of a recovered aqueous solution were obtained. The analytical values of the washed primary salt cake and the washed and recovered aqueous solution are shown in Table 1.

The filtrate was cooled to 20 ° C. over 1 hour and kept at 20 ° C. for 1 hour to crystallize EDS sodium salt, which was then centrifuged at room temperature for solid-liquid separation. . The filtrate amount is 1165.9 g, the centrifugal filter cake is washed with about 7 g of water as in the previous case, and the aqueous solution is used for washing the cake, and at the same time, 10.5 g of water is used.
The cake was further washed with to obtain 55.5 g of a washed EDS sodium salt cake and 25.6 g of a wash recovery aqueous solution. Table 1 shows the analytical values of the washed EDS sodium salt cake and the washed and recovered aqueous solution.

The filtrate from which the EDS sodium salt was removed was again immersed in an oil bath, and water was evaporated under reduced pressure of -510 mmHg to concentrate the inorganic salt while crystallizing the inorganic salt. Evaporated water amount 44
When the concentration became 0 ml and the concentration was stopped and the concentrated liquid was measured, the amount of the concentrated liquid was 720.3 g.

This concentrated liquid was circulated in warm water of about 85 ° C., poured into a heat-retaining centrifugal filter, and solid-liquid separated to obtain 562.8 g of a filtrate.

As in the previous case, about 15 g of water was placed in a container to dissolve and wash the adhered solid matter, and the centrifugal cake was washed with the aqueous solution, and the centrifugal cake was washed with 24.4 g of water to wash the secondary salt. 149.9 g of cake and 44.
6 g was obtained. The analytical values of the washed secondary salt cake and the recovered water of the washing are shown in Table 1.

To this filtrate was added 19.7 g of water and the temperature was 85 ° C.
The temperature was raised to 20 ° C. to obtain a transparent liquid, which was then cooled to 20 ° C. over 1 hour and kept at 20 ° C. for 30 minutes to crystallize methylaminoethanesulfonic acid. This crystallization liquid was poured into a centrifugal filter at room temperature and solid-liquid separation was carried out to obtain 421.8 g of a filtrate.
The centrifuge cake was washed with water in which the container was washed with approximately 8 g of water, and then with 15.1 g of fresh water, and 134.2 g of the washed methylaminoethane sulfonic acid cake and 41.5 g of the same washing recovery aqueous solution. Got The analytical values are shown in Table 1.

Further, 118.7 g of the washed methylamine ethanesulfonic acid cake was put into a vacuum dryer set at 70 ° C. and dried for about 6 hours to obtain 108.8 g of powder. Methylaminoethanesulfonic acid was analyzed by liquid chromatography, EDS sodium salt and methylaminodiethanesulfonic acid were analyzed by ion chromatography, salt and sodium sulfate were analyzed by titration method, and water was analyzed by Karl Fischer method. Acid = 98.71
%, Methylaminodiethanesulfonic acid = 0.04%, E
The values of DS sodium salt = 0.02%, common salt = 0.11%, mirabilite = 0.00%, water = 1.09% were obtained.

[0037]

[Table 1]

Example 2 Primary aqueous solution for washing and recovering salt washed in Example 1 33.0
g, 10.7 g of EDS sodium salt washed and recovered water, 29.3 g of secondary salt washed and recovered water, 23.0 g of methylaminoethanesulfonic acid washed and recovered aqueous solution, and 396.8 g of methylaminoethanesulfonic acid separated filtrate. Into a 3 liter separable flask was placed 1314.7 g of a fresh aqueous solution having the same composition as used in 1.
g was added dropwise to adjust the pH to 5.98, the flask was immersed in an oil bath and heated, and water was evaporated and concentrated under atmospheric pressure.

When the amount of evaporated water reaches about 305 ml,
The liquid became cloudy due to crystallization, so the concentration was stopped and the concentrated liquid was weighed to be 1555.4 g. This concentrated liquid was cooled to 20 ° C., and further maintained at 20 ° C. for 1 hour, then poured into a centrifugal filter at room temperature to perform solid-liquid separation, and 1481.
5 g of filtrate was obtained.

The centrifuge cake was washed with a recovered aqueous solution in which the container was washed with about 7.5 g of water, and fresh water was added at 11.0.
It was washed with g to obtain 60.1 g of washed EDS sodium salt cake and 26.9 g of the same recovered washing aqueous solution. The analytical values of these washed EDS sodium cakes and the same recovered washing aqueous solution are shown in Table 2.

The filtrate from which EDS sodium had been removed was again immersed in an oil bath, heated and concentrated under a reduced pressure of −410 mmHg to crystallize an inorganic salt. Evaporated water volume is about 495 ml
When the concentration became, the concentration was stopped, and the concentration of the concentrated liquid was measured, and it was 980.5 g. This concentrated liquid was poured into a centrifugal filter in which warm water of 85 ° C was circulated in a jacket and solid-liquid separated in the same manner as in Example 1 to obtain 787.6 g of a filtrate. The centrifuge cake was first washed with an aqueous solution in which the container was washed with about 15 g of water, and then with 23 g of water to obtain 182.0 g of the washed primary salt cake and 43.3 g of the recovered aqueous solution for washing the primary salt.
Got The analytical values of the washed primary salt cake were the values shown in Table 2.

This filtrate was mixed with the primary salt washing and recovery aqueous solution, and the container was again immersed in an oil bath and heated to -510 mm.
The water was evaporated under reduced pressure of Hg, and the inorganic salt was concentrated while crystallizing. When the amount of evaporated water reached about 195 ml, the concentration was stopped to obtain 634.3 g of a concentrated slurry liquid. This was again applied to a centrifugal filter in which warm water of 85 ° C was circulated through a jacket, and solid-liquid separation was performed to obtain 564.8 g of a filtrate. The cake was washed with about 7 g of water, washed with an aqueous solution thereof, and then washed with 10.4 g of water to obtain 63.2 g of a washed secondary salt cake and 17.9 g of a recovered washing aqueous solution.
These analytical values were the values shown in Table 2.

To this filtrate was added 19.8 g of water and the temperature was 85 ° C.
After heating to 20 ° C to make a transparent liquid, the liquid is cooled to 20 ° C to crystallize methylaminoethanesulfonic acid, further held at 20 ° C for about 1 hour, and then centrifugally filtered at room temperature to obtain 425.5 g of a filtrate. Got The centrifugal cake was washed with an aqueous solution in which the container was washed with about 7.5 g of water, and then further washed with 11.7 g of water,
Washed methylaminoethanesulfonic acid cake 135.5 g
34.7 g of the same washing and recovery aqueous solution was obtained.

The analytical values are shown in Table 2.

[0045]

[Table 2]

Example 3 Methylaminoethanesulfonic acid sodium salt and CES
Methylaminoethanesulfonic acid = 0.93%, methylaminodiethanesulfonic acid = 24.04%, and salt = 6.08%, which were synthesized from sodium salt, pH = 10.
657.0 of an aqueous solution of 65 and 1207.5 g of the same composition liquid as used in Example 1 were put in a 3 liter separable flask and mixed, and 80.9 g of 98% sulfuric acid was added dropwise.
After adjusting the pH to 5.2, the container was immersed in an oil bath and heated, and water was evaporated and concentrated under atmospheric pressure.

When the amount of evaporated water reached 400 ml, precipitation of crystallized substances was observed. Therefore, the concentration was stopped, and 1379.
5 g of concentrated liquid was obtained. This concentrated solution was cooled in the same manner as in Example 2 to crystallize EDS sodium salt, subjected to centrifugal filtration at room temperature, solid-liquid separated, and filtrate 1335.6 g.
Got The centrifugal cake was washed with a total of 13.2 g of water to obtain 27.1 g of washed EDS sodium salt cake and 22.3 g of the same washing recovery aqueous solution. These analytical values were as shown in Table 3.

The filtrate was concentrated again in the same manner as in Example 2 to crystallize the inorganic salt, and when the amount of evaporated water reached 450 ml, the concentration was discontinued to obtain 883.1 g of a concentrated slurry liquid. This concentrated liquid was subjected to a solid-liquid separation by applying a centrifugal filter which was kept warm, to obtain 708.8 g of a filtrate. Centrifuge cake is 3
Washed with 4.9 g water, washed primary salt cake 164.6 g
The same washing and recovery aqueous solution (35.9 g) was obtained. The analytical values of the washed salt cake are shown in Table 3.

This filtrate and the washed and recovered aqueous solution were mixed, immersed in an oil bath, and about 190 ml of water was evaporated under reduced pressure to concentrate the solution to obtain 552.2 g of a concentrated slurry liquid. The concentrate was subjected to solid-liquid separation using a heat-retention centrifugal filter to obtain 467.3 g of a filtrate. The centrifuge cake was washed with a total of 21.3 g of water in the same manner as in Example 2 to obtain 76.0 g of a cake containing methylaminodiethanesulfonic acid and 21.3 g of the same washing recovery aqueous solution as a washing secondary salt cake. The analytical values are shown in Table 3.

17.5 g of water was added to the filtrate, and the temperature was raised to a transparent liquid, followed by cooling to 20 ° C. to crystallize methylaminoethanesulfonic acid, and solid-liquid separation was carried out by centrifugal filtration at room temperature. 354 g of filtrate was obtained, and the total of the centrifugal filter cake was 17.
It was washed with 8 g to obtain 108.7 g of washed methylaminoethane sulfonic acid cake and 32.2 g of the same washing recovery aqueous solution. These analytical values were the values shown in Table 3.

[0051]

[Table 3]

Example 4 EDS cleaning recovery aqueous solution recovered in Example 3 = 10.5
g, secondary salt washing / collection aqueous solution = 10.9 g, methylaminoethanesulfonic acid washing / collecting aqueous solution = 21.5 g, methylaminoethanesulfonic acid separation filtrate = 342.7 g, and the same tissue fluid as the fluid used in Example 1. = 1137.7 g was put into a 3 liter separable flask, 107.4 g of 35% hydrochloric acid was added dropwise with stirring to adjust pH = 5.2, and
The same experiment as in Example 3 was performed, and the experimental results shown in Table 4 were obtained.

[0053]

[Table 4]

Comparative Example 1 2650.0 g of the same composition used in Example 1 was placed in a 3 liter separable flask and 35% hydrochloric acid 250.2 was added.
After g was added dropwise to adjust the pH to 6.0, the container was immersed in an oil bath and concentrated under atmospheric pressure. As in Example 1, when the amount of evaporated water reached about 790 ml, the concentrated liquid became cloudy due to crystallized substances, but the concentration was further continued, and the concentration was stopped when the amount of evaporated water was 1410 ml. The concentrated liquid amount was 1485.7 g.

Promptly, do not cool this concentrate 85
Apply a centrifuge filter that circulates warm water at ℃ in the jacket to solidify.
Liquid separation was performed to obtain 1240.8 g of a filtrate. The centrifugal cake was washed with a total of 49.0 g of water in the same manner as in Examples 2 to 4, and 226.3 g of the washed primary salt cake and the recovered washing aqueous solution 5
9.1 g was obtained. Table 5 shows the analytical values of the washed primary salt cake.

The filtrate and the recovered washing aqueous solution are mixed, the container is again immersed in an oil bath, and concentrated under atmospheric pressure. When the amount of evaporated water is about 470 ml, the concentration is stopped and the concentrated slurry liquid 8 is added.
26.3 g was obtained. This concentrate is approximately 90% as before.
Apply hot water at ℃ to a centrifugal filter that circulates through a jacket,
40.9 g of filtrate was obtained. Centrifugal cake is 45.6g in total
The washed secondary salt cake (171.5 g) and the same washed recovered aqueous solution (52.1 g) were obtained. These analytical values were the values shown in Table 5.

The filtrate was cooled to 20 ° C. with slow stirring as it was without adding water, further cooled to 20 ° C. for 1 hour, and kept at 20 ° C. for another hour to crystallize methylaminoethanesulfonic acid. I let it out. This slurry liquid was subjected to centrifugal filtration at room temperature to obtain 424.0 g of a filtrate. The centrifugal cake was washed with a total of 32.6 g of water to obtain 180.4 g of the washed methylaminoethanesulfonic acid cake and 55.8 g of the same washing recovery aqueous solution. These analytical values were the values shown in Table 5.

[0058]

[Table 5]

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C07C 309/14 C07C 303/44 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. An aminoethane sulfonic acid ammonium salt or an N-substituted aminoethanesulfonic acid N-substituted amine obtained by reacting (I) an aqueous solution of a β-chloroethanesulfonic acid alkali metal salt with ammonia or an N-substituted amine. After adding an alkali metal hydroxide to the salt to convert it into an alkali metal salt, the reaction aqueous solution is distilled, and (II) a mineral acid is added to the obtained aqueous solution to adjust the pH to 4.5 to 7.0. Converting the alkali metal salt to aminoethanesulfonic acid or N-substituted aminoethanesulfonic acid, (II
I) The obtained aqueous solution is concentrated by evaporating water under atmospheric pressure or under reduced pressure to obtain a saturated aqueous solution, the saturated aqueous solution is cooled to 20 ° C. or lower, and the crystallized impurities are removed by filtration. (IV) The resulting aqueous solution was concentrated again while evaporating water under atmospheric pressure or reduced pressure to partially crystallize impurities, and the crystallized product was filtered while keeping the temperature at 80 ° C. or higher to obtain a solid. -Liquid separation, (V) After diluting the obtained separated liquid with 3.5% or more and 30% or less of the aqueous solution, the diluted aqueous solution is cooled to room temperature and aminoethane sulfone is added. A method for purifying aminoethanesulfonic acids, which comprises a step of partially crystallizing an acid or N-substituted aminoethanesulfonic acid and subjecting the crystallized product to solid-liquid separation at room temperature. 2. The separated liquid obtained in step (V) is added to step (I).
Mixed with the aqueous solution obtained in step (1) to step (V)
A method for circulating and purifying aminoethanesulfonic acids, which comprises repeating