JPH078843B2 - Method for producing unsaturated quaternary ammonium salt - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an unsaturated quaternary ammonium salt, and more particularly to dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate methyl chloride No. 4 The present invention relates to a method for industrially producing an aqueous solution of a primary ammonium salt with high purity.

The unsaturated quaternary ammonium salt is a raw material of a cationic polymer and the like, and is an industrially useful substance used in a wide range of fields such as a polymer flocculant, a paper strengthening agent and an antistatic agent. Among them, a methyl chloride quaternary ammonium salt of dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate is often used as a cationic monomer used as a raw material of the polymer flocculant.

(Prior Art and Problems) As a cationic monomer which is a raw material for a cationic polymer, a vinyl monomer having a tertiary amino group is used as an acid such as hydrochloric acid or sulfuric acid, or 4 monomers such as methyl chloride, dimethyl sulfuric acid or benzyl chloride. An unsaturated salt obtained by treating with a grading agent is used, and the cationic monomer is polymerized in the state of an aqueous solution to be used for producing a cationic polymer flocculant and the like.

The unsaturated quaternary ammonium salt is synthesized by a quaternization reaction called a Menschutkin reaction, but it is an exothermic reaction, and when the temperature rises, thermal polymerization of the unsaturated quaternary ammonium salt easily occurs, and A problem in industrial processes is that unsaturated quaternary ammonium salts are solid and difficult to handle.

Therefore, in general, when synthesizing a methyl chloride quaternary ammonium salt of dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate, methyl chloride as a quaternizing agent is gradually supplied in the presence of an organic compound or water as a solvent. The method of reacting while heating is adopted.

When water is used as the solvent in this reaction, a high-concentration aqueous solution can be obtained without precipitating the unsaturated quaternary ammonium salt due to its large degree of solvent, but on the other hand, dimethylaminoethyl acrylate or dimethyl Hydrolysis of aminoethyl methacrylate is likely to occur, and there is a problem that the quality and yield of the target unsaturated quaternary ammonium salt are reduced due to impurities derived from the hydrolysis product.
In particular, a reduction in product purity is disadvantageous in that the degree of polymerization is lowered as a raw material of a cationic polymer which is the final application.

Therefore, in the quaternization of a vinyl monomer having a tertiary amino group in an aqueous solvent, it is important to prevent hydrolysis as much as possible, and various methods have been proposed for that purpose.

For example, in JP-A-51-76216, 50 ° C or less, particularly 10 to 30 ° C.
It is disclosed to react at the temperature of. JP-A-52-
In 31016 and JP-A-52-31017, the presence of an unsaturated quaternary ammonium salt in advance and the initial concentration of the raw material of 80
% Or more, and it is also preferable to react at a temperature of 25 to 40 ° C. Also, JP-A-57-
In 126452, it is disclosed that water is intermittently or continuously added in parallel with the addition of the quaternizing agent. Furthermore, in order to suppress hydrolysis, it is recommended to carry out the reaction at a relatively low temperature of 20 to 40 ° C. Has been done.

When the temperature is low in these quaternization reactions, the rate of hydrolysis of the raw materials can be reduced, but at the same time, the reaction rate also decreases, so the space-time yield of the target unsaturated quaternary ammonium salt is reduced. There is a problem that it drops significantly. In addition, when the initial concentration of the raw material is high, precipitation of unsaturated quaternary ammonium salt and generation of scale are likely to occur due to the reaction in a supersaturated state, so that the stirring load of the reaction solution is increased and the reaction temperature is controlled. There is a problem that stable operation on an industrial scale is difficult, such as becoming difficult.

Further, JP-A-55-127351 proposes to carry out the reaction while maintaining the pH of the reaction solution at 6 to 9, and as a concrete method, a quaternizing agent is charged in advance and the vinyl monomer as a raw material is used. And water are added dropwise so that the pH in the system is maintained at 6-9. However, when the quaternizing agent is methyl chloride, a higher pressure reactor is required, which is an industrially disadvantageous method.

Further, in JP-A-61-50947, in the case of using dimethylaminoethyl arylate as a raw material, in order to suppress the by-product of acrylic acid, an aprotech low boiling point organic solvent having compatibility with water is used. It proposes a method of reacting an alkyl (meth) acrylate with methyl chloride while intermittently or continuously adding the mixed solution of (1). However, in the case of using an organic solvent together, an operation of separating and recovering the solvent is necessary, but especially for the use of solvent recycling, an operation such as the removal of a trace amount of accumulated impurities is indispensable, which makes the process complicated industrially. However, it becomes a disadvantageous method in terms of energy cost.

As described above, when dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate is quaternized with methyl chloride, an efficient production method that suppresses the hydrolysis rate of the raw material as much as possible and is also industrially satisfactory is not yet available. The current situation is that it has not been developed.

(Means for Solving the Problems) In view of various drawbacks as described above, the present invention provides an aqueous solution of dimethylaminoethyl acrylate or a methyl chloride quaternary ammonium salt of dimethylaminoethyl methacrylate with high purity and industrially. The present invention provides a method for obtaining the advantage.

The present inventors have studied quaternization reaction with methyl chloride in the presence of water using dimethylaminoethyl acrylate, which is more easily hydrolyzed as a raw material, than dimethylaminoethyl acrylate, and found that when the reaction temperature is high It is not preferable because the degree of decomposition is large and the reaction rate decreases, but it is unavoidable to carry out the reaction at a temperature of 30 ° C. or lower, and the hydrolysis rate is not sufficient even in such a reaction at a low temperature, It has been found that it is difficult to suppress the amount to 1 mol% or less.

However, by introducing an aqueous solution of methyl chloride quaternary ammonium salt of dimethylaminoethyl acrylate into the reaction system at a rate proportional to the supply of methyl chloride from the initial stage of the reaction or immediately after the start, a sufficient reaction rate is obtained. The hydrolysis rate can be controlled to 1 mol% or less at a relatively high temperature of around 45 ° C, and the precipitation of the unsaturated quaternary salt produced and the sudden rise of the reaction temperature can be suppressed, and the target quaternary salt can be obtained in a stable state. The inventors have found that the oxidization reaction can be carried out, and have completed the method of the present invention.

That is, according to the present invention, when methyl chloride is supplied to dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate to react with each other to produce a methyl chloride quaternary ammonium salt aqueous solution of the acrylate or methacrylate, it is proportional to the supply of methyl chloride. By introducing the methyl chloride quaternary ammonium salt aqueous solution of acrylate or methacrylate at a rate in parallel with the supply of methyl chloride and reacting at a temperature of 40 to 50 ° C., the quaternary salt with high quality and high yield can be obtained. It is a method of obtaining an aqueous solution.

The method of the present invention will be further described below. When methyl chloride is supplied to dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate for reaction, an aqueous solution of the methyl chloride quaternary ammonium salt of acrylate or methacrylate introduced into the reaction system in parallel with the supply of methyl chloride is It can be arbitrarily selected in a range lower than the saturation concentration, but a range of 5 to 40% is preferable. The amount of the methyl chloride quaternary ammonium salt of the acrylate or methacrylate as a solute of the solution introduced into the reaction system is 1 mol% with respect to the raw material dimethylaminoethyl acrylate or methacrylate.
The above is preferable.

The introduction of the solution is started after the supply of methyl chloride is started.
Alternatively, it is preferably carried out immediately after the start of the reaction, and it is carried out so as not to cause a rapid rise in the temperature of the reaction solution or precipitation of the produced methyl chloride quaternary ammonium salt too late.

Further, the introduction of the solution can be carried out intermittently, but it is most preferably carried out continuously.

Methyl chloride, which is a quaternary agent, can be supplied in a gaseous form or a liquid form, but is preferably equimolar or more to the acrylate or methacrylate, and preferably in the range of 1.01 to 1.05.

The reaction temperature when satisfying the requirements of the present invention is 35 to 55 ° C, particularly
The range of 40 to 50 ° C is preferred.

Further, in the method of the present invention, it is preferable to use a polymerization inhibitor in order to carry out the reaction at a relatively high temperature.
-Methoxyphenol and the like can be used, and the addition amount of the polymerization inhibitor to the acrylate or methacrylate is preferably in the range of 1000 to 4000 ppm.

After carrying out the quaternization reaction by the method of the present invention as described above,
It is effective to improve the quality of the product that the aging time of 0.5 to 4 hours is taken for the reaction product solution.

Then, a bubbling operation with air or the like is performed on this reaction product solution to separate a slight excess of methyl chloride, thereby obtaining a high yield of an aqueous solution of the methyl chloride quaternary ammonium salt of the acrylate or methacrylate of the product. It can be obtained in purity.

〔Example〕

Hereinafter, the method of the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

When dimethylaminoethyl acrylate is hydrolyzed, it becomes dimethylaminoethanol and acrylic acid, part of which forms a salt of dimethylaminoethanol and acrylic acid, and part of which is quaternized with methyl chloride and saturated quaternary
Form a quaternary ammonium salt. After completion of the quaternization reaction, the hydrolysis rate of dimethylaminoethyl acrylate was evaluated by the following method. The reaction product liquid is analyzed by liquid chromatography, by-produced free dimethylaminoethanol, dimethylaminoethanol and acrylic acid salts, and dimethylaminoethanol and methyl chloride salts and the like are quantified,
The hydrolysis rate was calculated.

Example 1 A 100 glass lining reaction vessel equipped with a stirrer containing 2000 ppm of p-methoxyphenol, a polymerization inhibitor, having a purity of 99.
78% Dimethylaminoethyl acrylate 23.05Kg (16
(0.6 mol) was charged, sealed and heated to 43 ° C.

Then, with stirring, 8.27 Kg (164 mol) of methyl chloride was supplied at a constant rate over 5.9 hours.

Immediately after the start of the reaction, the introduction of a separately prepared 10.5% concentration aqueous solution of dimethylaminoethyl acrylate methyl chloride quaternary ammonium salt was started, and 8.88 kg was maintained at a constant rate of 6%.
Introduced over time.

The reaction temperature could be stably controlled at about 47 ° C.

After the reaction product solution was aged for 2 hours, excess methyl chloride was removed by aeration to obtain 39.74 Kg of a methyl chloride quaternary ammonium salt aqueous solution of dimethylaminoethyl acrylate. The aqueous solution of this product was 79.4%, which was within the target concentration range, and the hydrolysis rate of the acrylate could be suppressed to as low as 0.8 mol%.

Example 2 The same reaction vessel as in Example 1 was charged with 23.05 Kg (160.6 mol) of the same dimethylaminoethyl acrylate and sealed.
Heated to 38 ° C.

Next, with stirring, 8.43 Kg (167 mol) of methyl chloride was supplied at a constant rate for 4.9 hours.

Immediately after the start of the reaction, introduction of an aqueous solution of dimethyl quaternary ammonium salt of dimethylaminoethyl acrylate having a concentration of 26.9% prepared from the aqueous solution of the product obtained in Example 1 was started, and 9.35 Kg was introduced at a constant rate for 5 hours. did. The reaction temperature could be stably controlled at about 40 ° C.

After the reaction product solution was heated to 45 ° C and aged for 2.5 hours, 1.54 kg of water was newly added, and then excess methyl chloride was removed by aeration, and a methyl chloride quaternary ammonium salt aqueous solution of dimethylaminoethyl acrylate 4
Obtained 1.79 Kg. The aqueous solution of this product was 79.6%, which was within the target concentration range, and the hydrolysis rate could be suppressed to a low value of 0.75 mol%.

Comparative Example 1 The same aqueous solution as the product in Example 1 was placed in the same reaction vessel as in Example 1.
6.67 Kg was charged, followed by 23.05 Kg (160.6 mol) of dimethylaminoethyl acrylate and 6.18 Kg of water as in Example 1.
Was charged, sealed and heated to 38 ° C. Immediately after reaching 38 ° C,
With stirring, supply of methyl chloride was started, and 8.43 Kg (16
7 mol) was fed at a constant rate over 4.9 hours. The reaction temperature during the feeding of methyl chloride was controlled at about 40 ° C.

The reaction system internal pressure after completion of the supply of methyl chloride was determined in Example 1,
It was higher than that of 2, and the reaction product solution was heated to 45 ° C. and aged for 5 hours. Thereafter, 1.54 kg of water was newly added, and then excess methyl chloride was removed by aeration to obtain 54.66 kg of an aqueous methyl chloride quaternary ammonium salt solution of dimethylaminoethyl acrylate. This product aqueous solution has a concentration of 62%, well below the target concentration of around 80%,
The hydrolysis rate also deteriorated significantly to 12.3 mol%. Examples 1 and 2
Compared with, the yield is greatly reduced, the hydrolysis rate is greatly increased,
The product was unsuitable in terms of quality.

Comparative Example 2 The same reaction vessel as in Example 1 was charged with 23.05 kg (160.6 mol) of dimethylaminoethyl acrylate as in Example 1, sealed and heated to 43 ° C. Then, with stirring, 8.27 Kg (164 mol) of methyl chloride and 7.72 Kg of water were supplied at a constant rate over 5.9 hours and 6 hours. The reaction temperature was controlled at about 47 ° C. After aging the reaction solution for 21 minutes, excess methyl chloride was removed by aeration to obtain 38.45 Kg of dimethylaminoethyl acrylate aqueous solution of quaternary ammonium salt of methyl chloride. This aqueous solution had a lower concentration than the target concentration of 76.9% and a large hydrolysis rate of 3.5 mol%, which was an insufficient value as compared with Examples 1 and 2, and was unsatisfactory as a product.

(Effect of the Invention) In the method of the present invention, when dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate is reacted with methyl chloride to produce a methyl chloride quaternary ammonium salt of the acrylate or methacrylate, the quaternary ammonium salt is used. By supplying a part of the salt aqueous solution to the reaction system together with methyl chloride, the raw material hydrolysis rate is suppressed to 1 mol% or less at a relatively high reaction temperature, and an industrially high-quality unsaturated quaternary ammonium salt is obtained. Aqueous solutions can be produced in high yield. Moreover, since the method of the present invention has a high reaction temperature, it is advantageous in industrial processes in terms of reaction rate and heat removal. In particular, the method of the present invention is most effectively applied to the quaternization reaction of highly hydrolyzable dimethylaminoethyl acrylate.

Claims (1)

[Claims] 1. When dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate is supplied with methyl chloride and reacted to produce a methyl chloride quaternary ammonium salt of the acrylate or methacrylate, at a temperature of 40 to 50 ° C., methyl chloride. The method for producing an unsaturated quaternary ammonium salt aqueous solution, which comprises introducing and reacting the quaternary ammonium salt aqueous solution in parallel at a rate proportional to the supply.