JP2000128854A - Production of acrylamidoalkanesulfonic acid salt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively obtain the subject compound of constant polymerizability by directly neutralizing a reaction liquor produced by reaction between acrylonitrile and an olefin in an acidic condition with sulfuric acid to effect raising reaction solvent recovery and cutting wastes including waste liquor sludge. SOLUTION: This compound such as 2-acrylamido-2-methylpropanesulfonic acid salt is obtained by directly neutralizing, with e.g. an aqueous solution of sodium hydroxide or the like, a reaction liquor produced by reaction between acrylonitrile and an olefin (pref. an aliphatic olefin, esp. isobutene) in an acidic condition with sulfuric acid, followed by recovering pref. the acrylonitrile unreacted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Sodium acrylate polymers and acrylamide polymers are widely used as dispersants for papermaking and coagulants for water treatment, but the present invention relates to copolymers that modify the properties of these polymers. The present invention relates to an acrylamide alkane sulfonate, which is also widely known as an ionic monomer, and particularly relates to a method for efficiently and inexpensively producing acrylamide alkane sulfonate, which belongs to a chemical production technology. Things.

[0002]

2. Description of the Related Art Acrylamide alkanesulfonic acid and salts thereof are used for various purposes by themselves.
Homopolymers or copolymers as described above are also used for various purposes. For example, a polymer electrolyte containing acrylamide alkane sulfonate as a constituent monomer is used as an admixture for cement, an additive for oil drilling and recovery, and the like, and the polymer electrolyte is widely used for various other uses. . Therefore, there is a strong demand for supplying acrylamidoalkanesulfonic acid and salts thereof at low cost and with good quality (having good polymerizability and stability). In general, acrylamide alkanesulfonic acid salts, for example, sodium salts, are prepared by neutralizing acrylamide alkanesulfonic acid with sodium hydroxide, sodium carbonate, etc., and other salts by neutralizing ammonium hydroxide, amine with water or an organic solvent. ing. And acrylamide alkane sulfonic acid as a raw material is
It is produced by adding a predetermined amount of sulfuric acid or fuming sulfuric acid and an olefin to an excess amount of acrylonitrile, which serves as a raw material and a solvent, and reacting the resulting mixture. .

[0003] However, the inventors of the present invention disclose published patent application 2-50.
Although the method described in Japanese Patent No. 0188 was additionally tested, first of all, regarding the recovery of unreacted raw material acrylonitrile, the recovery rate of acrylonitrile was low due to loss during distillation, and a satisfactory result was not obtained. Further, the reaction product obtained by the method described in the above-mentioned JP-B-50-30059 is recovered by filtration with a glass filter, dried, and then the obtained crystals are neutralized with sodium hydroxide. The obtained reaction filtrate was neutralized with an aqueous sodium hydroxide solution, and acrylonitrile was recovered by distillation.
In this method, equipment and operation for separating and drying the crystals from the reaction product, equipment and operation for neutralizing the crystals, and equipment and operation for recovering acrylonitrile from the filtrate and the like are separately required, and equipment and labor costs are reduced. It was economically unfavorable and the recovery of acrylonitrile was low.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have improved the amount of raw acrylonitrile recovered by simple equipment and operation without the above-mentioned problems, and at the same time, improved the quality (polymerization is good and stable). The enthusiastic study was conducted to provide a method for producing an acrylamide alkane sulfonate with good efficiency, economic efficiency and low cost.

[0005]

Means for Solving the Problems The inventors of the present invention prepared a conventional production method, that is, neutralize acrylamide alkanesulfonic acid obtained by purification to obtain a salt thereof, and convert acrylonitrile and olefin under sulfuric acid. Acrylamide alkane sulfonic acid was obtained by directly neutralizing the reaction solution without separating and purifying the acrylamide alkane sulfonic acid from the reaction solution obtained by reacting the unreacted raw material and solvent, and After that, by performing purification and recovery, etc.,
The inventors have found that the above-mentioned problems can be solved and completed the present invention.

That is, the present invention relates to a process for producing an acrylamide alkane sulfonate, which comprises directly neutralizing a reaction solution obtained by reacting acrylonitrile and an olefin under sulfuric acidity. In the invention relating to a method for producing an acrylamide alkane sulfonate, which comprises directly recovering acrylonitrile after directly neutralizing a reaction solution obtained by reacting under acidic conditions, and in those inventions, the acrylamide alkane sulfonate is 2-acrylamide. The present invention relates to a method for producing acrylamide alkane sulfonate, which is 2-methylpropane sulfonate.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Acrylonitrile as a raw material used in the present invention can also serve as a reaction solvent, but there is no particular limitation in quality and the like, and the purpose is sufficiently achieved by generally commercially available industrial use. . The reaction between acrylonitrile and sulfuric acid or fuming sulfuric acid proceeds in equimolar amounts.Acrylonitrile reacts with acrylonitrile because the acrylamidoalkanesulfonic acid generated with the progress of the reaction may precipitate, increasing the concentration of the reaction solution and making stirring difficult. It is desirable that the acrylonitrile function also as a solvent, and therefore, it is desirable that acrylonitrile be used in an amount of 4.0 mol or more per 1 mol of sulfuric acid or fuming sulfuric acid. Sulfuric acid or fuming sulfuric acid may be ordinary sulfuric acid or fuming sulfuric acid, but it is desirable that the amount of iron contained is as small as possible. If the amount of iron exceeds, for example, 20 ppm, the resulting acrylamide alkanesulfonic acid will have a problem of discoloration. The type of olefin is not particularly limited, and may be selected depending on the intended acrylamide alkanesulfonic acid, and may be any olefin such as ethylene, propene, butene, pentene, hexene, styrene, and methylstyrene, but is preferably an aliphatic olefin. And particularly preferably isobutene. The product when using isobutene as the olefin is 2-acrylamido-2-methylpropanesulfonic acid. The preferable addition ratio of the olefin is 0.8 to 1.2 mol, more preferably 0.8 to 1.0 mol, per 1 mol of sulfuric acid. When the addition ratio of the olefin is less than 0.8 mol per mol of sulfuric acid, the acrylamide alkane sulfonate may be colored,
If it exceeds 1.2 mol, there is a possibility that by-products increase.

The reaction conditions of acrylonitrile, sulfuric acid or fuming sulfuric acid and an olefin are not particularly limited. For example, a two-step continuous reaction in which acrylonitrile is mixed with sulfuric acid or fuming sulfuric acid, and then an olefin is added and reacted, and A one-step continuous reaction in which the components are mixed at once and reacted is mentioned, and a preferable reaction temperature is -10.
To 70 ° C, more preferably 30 to 50 ° C. If the reaction temperature is higher than 70 ° C., the amount of by-products of the olefin sulfonate increases, and the product tends to be colored. Conversely, if the reaction temperature is lower than −10 ° C., the sulfate ester is by-produced. It tends to decrease. The alkali used for neutralization is not particularly limited, and any inorganic or organic alkali may be used. For example, inorganic alkalis include hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, sodium carbonate, and hydrogen carbonate. A weak acid salt such as sodium and an organic alkali can be used according to a salt for which ammonium hydroxide or an alkylamine such as methylamine or triethylamine is required. A solvent can be used for the reaction and neutralization, and the solvent used is not particularly limited, and water and various organic solvents can also be used. When neutralized with an inorganic alkali such as sodium hydroxide or sodium carbonate, water or dimethylformamide,
It is preferable to use a polar organic solvent such as dimethyl sulfoxide, ethylene glycol, and methyl alcohol.

The concentration of the alkali used for neutralizing the reaction product is not particularly limited, and may be a generally used industrial product. For example, a 48% by weight aqueous solution of sodium hydroxide or a Can be used after dilution. The amount of alkali used is stoichiometrically equivalent or close to acrylamidoalkanesulfonic acid. The pH of the aqueous layer after neutralization is in the range of 6 to 11, preferably 7 to 10. When the pH is lower than 6, the acrylamide alkane sulfonate solution produced tends to be polymerized during the storage operation and during storage, and when the pH is higher than 11, it is easily hydrolyzed during the treatment operation and during storage of the generated acrylamide alkane sulfonate solution. It is not preferable. The method of neutralizing the reaction product containing acrylamide alkanesulfonic acid is not particularly limited.For example, an alkali solution is put in advance, and the reaction product is slowly poured into a stirred vessel, or conversely, the reaction product is stirred. It is also possible to pour the alkaline solution slowly. The neutralization temperature is preferably between 5 and 60C. Due to the solubility of acrylamide alkane sulfonate obtained when the neutralization temperature is lower than 5 ° C., the reaction solution tends to be a slurry after neutralization, and more coolant is required to remove heat generated during neutralization. It is not economical. If the temperature is higher than 60 ° C., the obtained salt may be polymerized.

The temperature for removing the raw materials and the solvent such as acrylonitrile is preferably 100 ° C. or less. If the temperature is higher than 100 ° C., the obtained salt may be decomposed or polymerized, and if the raw material / solvent is a polymerizable compound such as acrylonitrile, it may be polymerized. The temperature is particularly preferably 60 ° C. or lower, in which case the removal is performed under reduced pressure of 400 torr or lower. As the atmosphere during the neutralization operation and the solvent removal operation, acrylonitrile and acrylamide alkanesulfonic acid or a salt thereof, which are solvents of the slurry, are easily polymerized when left in the absence of dissolved oxygen. It is better to perform operations such as handling in a mixed atmosphere, and to maintain a certain amount of dissolved oxygen.

For the same reason as described above, a polymerization inhibitor may be added at the time of neutralization and at the time of solvent removal. As the polymerization inhibitor to be used, any one such as hydroquinone, t-butylhydroquinone and hydroquinone monomethyl ether may be used. Although possible, hydroquinone monomethyl ether is preferred. The preferred amount of the polymerization inhibitor is 5 to the final acrylamide alkane sulfonate solution.
It is at most 00 ppm, particularly preferably at most 100 ppm. 5
If it exceeds 00 ppm, the effect of inhibiting the polymerization is strong, and the resulting acrylamide alkane sulfonate takes too long to polymerize.

The solution concentration of the acrylamide alkane sulfonate upon neutralization is preferably 20% by weight to 60% by weight.
If the concentration is lower than 20% by weight, the capacity of the container with respect to the production amount per unit time increases, and the equipment becomes large, which is not preferable. If the concentration is higher than 60% by weight, crystals may be precipitated, Handling becomes difficult.

[0013]

After the reaction, the acrylamide alkanesulfonic acid obtained by filtration and drying is neutralized with an alkali, and unlike the conventional method of forming a salt, the acrylamide alkanesulfonic acid after the reaction of the present invention is directly converted to an alkali. The method of neutralization to form a salt, with simple equipment and operation, improves the recovery amount of raw material acrylonitrile and efficiently manufactures acrylamide alkane sulfonate with good quality (polymerizable and stable). Thus, the recovery and reuse of the reaction solvent can be increased.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples.
The units shown in the examples are weight units. Reference Example 1 (Production of crude 2-acrylamido-2-methylpropanesulfonic acid) A stirrer and two glass reactors each having an inlet tube and an outlet tube were connected, and acrylonitrile and fuming sulfuric acid were converted to the first under the following conditions. Introduced into the reactor, acrylonitrile and fuming sulfuric acid were mixed, and the mixture was led to the second reactor,
The reaction was continuously carried out by introducing isobutylene gas into the reactor. Acrylonitrile was supplied at a rate of 10 mol per 1 mol of fuming sulfuric acid, and isobutylene was supplied at a rate of 0.9 mol to react. The concentration of fuming sulfuric acid is 9%
It is. The first reactor is maintained at -5 ° C to -15 ° C, the residence time is 10 minutes, and the second reactor is 30 ° C to 50 ° C.
C. and the residence time was 40 minutes.

Example 1 412 g of a 6% aqueous sodium hydroxide solution containing 30 ppm of hydroquinone monomethyl ether was cooled with ice water, and stirred while bubbling air with an air pump. Part 52 of the reaction product obtained
8 g was poured slowly, and after stirring for 10 minutes, the pH of the aqueous layer was measured. As a result, the pH was about 7, and a small amount of sodium hydroxide was added to adjust the pH to 8.5. Bath temperature about 60 ℃,
Acrylonitrile / water was distilled off at a reduced pressure of about 150 torr to obtain 494 g of an aqueous solution. The yield based on the charged isobutylene obtained by measuring the concentration of 2-acrylamido-2-methylpropanesulfonic acid by liquid chromatography was 93%. The recovery of acrylonitrile obtained by distillation was 95%. 123 g of acrylamide was added to an aqueous solution corresponding to 44 g of crude sodium 2-acrylamide-2-methylpropanesulfonate obtained by the above method.
Was mixed, and water was further added to adjust the monomer concentration to 20%. After replacing this aqueous solution with nitrogen, potassium persulfate 200pp
m and 200 ppm of sodium sulfite were added to initiate polymerization at 10 ° C. After 10 hours, the copolymer was taken out, and
After vacuum drying at 00 ° C. for 4 hours, it was pulverized. The viscosity of the obtained copolymer powder was measured under the following conditions using an aqueous solution, and the viscosity was 120 cp. (Conditions) Viscometer: B-type viscometer Rotor rotation speed: 6 rpm Concentration of aqueous solution: 0.1% aqueous solution Temperature of aqueous solution: 25 ° C

Example 2 35 mg of hydroquinone monomethyl ether was dissolved in 800 g of the reaction product obtained in Reference Example 1, cooled around with ice water, and stirred while bubbling air with an air pump. 250 g of a 20% aqueous sodium hydroxide solution was slowly poured. After stirring for 10 minutes, the pH of the aqueous layer was measured and found to be about 10. Therefore, a small amount of the reaction slurry was added to adjust the pH to 9. Acrylonitrile / water was distilled off at a bath temperature of about 50 ° C. and a degree of vacuum of about 300 torr to obtain 320 g of an aqueous solution. When the concentration of 2-acrylamido-2-methylpropanesulfonic acid was measured by liquid chromatography, the yield based on the charged isobutylene was 92%. The recovery of acrylonitrile obtained by distillation was 93%. Further, when the same polymerization evaluation was performed as described above, the viscosity was 110 cp.

Examples 3 to 6 Table 1 summarizes the results of performing treatment, recovery, and polymerization evaluation by changing the alkali and the neutralizing solvent in Examples 1 and 2.

Comparative Example 1 The reaction product obtained in Reference Example 1 was suction-filtered from the second reactor and dried under reduced pressure to obtain crude 2-acrylamido-2-methylpropanesulfonic acid. The yield was 91% based on the supplied isobutylene. According to Japanese Unexamined Patent Publication (Kokai) No. 2-500188, calcium hydroxide equivalent to the acid neutralization number and water equivalent to 3% by weight of the reaction product were added to unreacted sulfuric acid and acrylonitrile containing reaction impurities, which were mixed and stirred. . After removing the deposited precipitate using a centrifuge,
Distillation under reduced pressure was performed in the same manner as in Example 1 to recover acrylonitrile. The recovery of acrylonitrile was 85%. Further, about 10% by weight of the obtained crude 2-acrylamido-2-methylpropanesulfonic acid produced cake sludge containing calcium sulfate as a main component. Furthermore, crude 2-
Acrylamide-2-methylpropanesulfonic acid crystal 40 g
Was dissolved in 60 g of water while introducing air with an air pump, and a 16% aqueous NaOH solution was added to adjust the pH to 8. The polymerization was evaluated as in Example 1. Its viscosity was 140 cp.

Comparative Example 2 Similarly to Comparative Example 1, crude 2-acrylamido-2-methylpropanesulfonic acid was obtained. The yield was 91% based on the supplied isobutylene. According to JP-A-5-230007, 8% by weight of aqueous ammonia corresponding to the acid neutralization number was added to acrylonitrile containing unreacted sulfuric acid and reactive impurities which were separated by filtration, followed by mixing and stirring. The supernatant after standing separation was distilled under reduced pressure in the same manner as in Example 1 to recover acrylonitrile.
The recovery of acrylonitrile was 80%. Further, about 10% by weight of the obtained crude 2-acrylamido-2-methylpropanesulfonic acid generated wastewater containing ammonium sulfate as a main component. The polymerization performance of the neutralized salt was 140 cp as in Comparative Example 1.

Comparative Example 3 The reaction product solution obtained in Reference Example 1 was suction-filtered from the second reactor to obtain 2-acrylamido-2-methylpropanesulfonic acid to which the reaction solution was attached, and acrylonitrile having the same weight as the crystal was obtained. , And dried under reduced pressure to obtain crude 2-acrylamido-2-methylpropanesulfonic acid. The yield was 90% based on the supplied isobutylene. Tokiohei 2-500188
To the unreacted sulfuric acid and acrylonitrile containing reaction impurities, calcium hydroxide corresponding to the acid neutralization number and water equivalent to 3% by weight of the reaction slurry were added, followed by mixing.
Stirred. After removing the deposited precipitate using a centrifugal separator, distillation under reduced pressure was performed in the same manner as in Example 1 to collect acrylonitrile. The recovery of acrylonitrile was 70%. Further, about 10% by weight of the obtained crude 2-acrylamido-2-methylpropanesulfonic acid produced cake sludge containing calcium sulfate as a main component. The polymerization performance of the neutralized salt was 380 cp as in Example 1.

Comparative Examples 4 to 6 Table 2 summarizes the results of treating, recovering and evaluating polymerization by changing the alkali and the neutralizing solvent in Comparative Examples 1 and 2.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

According to the present invention, an acrylamide alkane sulfonate having good quality (constant polymerizability) can be produced at a low cost, the recovery rate of the reaction solvent is increased, and sludge such as waste liquid waste sludge is increased. An excellent effect is achieved in that waste can be reduced.

Claims (3)

[Claims] 1. A method for producing an acrylamide alkane sulfonate, which comprises directly neutralizing a reaction solution obtained by reacting acrylonitrile and an olefin under sulfuric acidity. 2. A process for producing an acrylamide alkane sulfonate, which comprises directly neutralizing a reaction solution obtained by reacting acrylonitrile and an olefin under sulfuric acidity and recovering acrylonitrile. 3. The acrylamide alkane sulfonate is
The method for producing acrylamidoalkanesulfonic acid salt according to claim 1 or 2, wherein the method is 2-acrylamido-2-methylpropanesulfonic acid salt.