JPH09286765A - Production of aminoalkyl (meth)acrylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aminoalkyl (meth)acrylate, capable of producing the aminoalkyl (meth)acrylate in a high yield by using an alkali metal alcoholate or an alkaline earth metal alcoholate. SOLUTION: Methyl methacrylate, dimethylaminoethanol, magnesium dimethylaminoethylate as a catalyst, and n-hexane as an azeotrpopic agent are charged into a reactor 1 and heated. A low boiling point fraction is cut off from the obtained reaction solution by the use of a rectification tower 2 for removing the unreacted raw materials, and the objective dimethylaminoethyl methacrylate is distilled out from the overhead of a rectification tower 3 for distilling the ester. The residues are heated in a rectification tower 10 for recovering the Michael addition product to distill out the high boiling point Michael addition product. The obtained Michael addition product is returned to the reactor 1 so that the concentration of the high boiling point Michael addition product in the reaction solution is 0.5-10.0wt.%. Since the Michael addition reaction in the reaction solution is thereby suppressed, the yield of the objective compound is improved.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aminoalkyl acrylate or aminoalkyl methacrylate using a transesterification reaction (hereinafter, the actrate and the methacrylate are collectively referred to as “(meth) acrylate”), and more specifically, to a method for producing the same. The present invention relates to a method for producing an aminoalkyl (meth) acrylate in which the yield is improved by suppressing the Michael addition reaction as a side reaction in the presence of a specific azeotropic agent. INDUSTRIAL APPLICATION This invention is utilized for the manufacturing method of dimethylaminoethyl (meth) acrylate, for example. In addition, the aminoalkyl group in the aminoalkyl (meth) acrylate in this specification refers to a disubstituted aminoalkyl group having two hydrocarbon groups.

[0002]

2. Description of the Related Art A method for producing an aminoalkyl (meth) acrylate by transesterification of an alkyl (meth) acrylate with an amino alcohol is already known. For example, when methyl (meth) acrylate and dimethylaminoethanol are used as raw materials, transesterification reaction between them produces dimethylaminoethyl (meth) acrylate and methanol. As the catalyst for the transesterification reaction, alkali metal alcoholates, alkaline earth metal alcoholates, organotin compounds such as dibutyltin oxide, and β-diketone metal compounds such as acetylacetone iron (JP-A-2-17155) are used. There is.

Further, JP-A-57-9739, JP-A-57-9740, and JP-A-58-18045.
No. 7 discloses that an organic solvent, which is hardly soluble in methanol and forms a minimum azeotrope with methanol, is added to a mixed solution of methyl methacrylate and methanol as an azeotropic agent, and distillation is carried out. A method for recovering methyl methacrylate that does not contain methanol is disclosed. The azeotropic mixture of methanol and organic solvent distilled from the top of the column is cooled and condensed, and then separated into an organic solvent layer and a methanol layer by two-layer separation to recover the organic solvent and methanol, respectively. The recovered organic solvent layer is returned to the original rectification column for reuse. Furthermore, JP-A-6-
No. 256271 discloses a method for producing an alkylaminoalkyl ester of (meth) acrylic acid, in which alkyl (meth) acrylate or aminoalkyl (meth) acrylate and methanol or It is disclosed that the Michael adduct with amino alcohol is added to the reaction system to improve the selectivity from raw materials to products.

[0004]

However, according to the method for producing an aminoalkyl (meth) acrylate by the above transesterification reaction, the starting amino alcohol and the by-produced alcohol are the starting material alkyl (meth) acrylate and the formed product. The so-called Michael addition reaction occurs in which the aminoalkyl (meth) acrylate is added to the double bond. Therefore, there is a problem that the yield and selectivity of the target product, aminoalkyl (meth) acrylate, are reduced.
There is a high demand in the art for yield and selectivity, and it is highly desirable to prevent these declines, even insignificant amounts.

As described above, various catalysts for the above transesterification reaction are known, but among them, when using an organotin compound such as dibutyltin oxide and a β-diketone metal compound as a catalyst, the selectivity is high. Although it is expensive, it has a drawback that the reaction takes a long time. Furthermore, all of these organotin compounds, acetylacetone metal compounds, and β-diketone zinc compounds are more expensive than alkali metal alcoholates and alkaline earth metal alcoholates, so that the production cost of aminoalkyl (meth) acrylate increases. There was a problem. On the other hand, alkali metal alcoholates or alkaline earth metal alcoholates are inexpensive, and when these are used as catalysts, the transesterification reaction is promoted more efficiently, but this Michael addition reaction is likely to occur, and therefore the amino acid The yield of alkyl (meth) acrylate tends to be significantly reduced. The present invention overcomes the above-mentioned drawbacks and provides an aminoalkyl (meth) which can be produced in high yield and can be efficiently produced.
An object is to provide a method for producing an acrylate.

[0006]

The present inventors have paid attention to the fact that the Michael addition reaction, which tends to occur when an alkali metal alcoholate or an alkaline earth metal alcoholate is used as a catalyst, is an equilibrium reaction. And (meta)
Michael addition reaction of methyl acrylate with methanol or aminoalcohol and / or aminoalkyl (meth) acrylate with methanol or aminoalcohol and azeotropic agent in the reaction solution The present invention has been completed on the finding that the above is efficiently suppressed and the yield of the target product is improved.

The method for producing an aminoalkyl (meth) acrylate according to the first aspect of the present invention comprises: methyl (meth) acrylate;
In a method for producing an aminoalkyl (meth) acrylate by a transesterification reaction in which a reaction liquid composed of an aminoalkyl alcohol represented by the following general formula is heated, in the reaction liquid, it is difficult to dissolve in methanol With an azeotropic agent that forms a minimum azeotrope with
A method for producing aminoalkyl (meth) acrylate, which comprises introducing a Michael adduct of each ester compound having a double bond and amino alcohol or methanol. [General Formula] R ₁ R ₂ N—R′—OH where R ₁ is a hydrocarbon group, R ₂ is a hydrocarbon group, and R ′ is an alkylene group.

In the above general formula representing the "aminoalkyl alcohol" of the present invention, R ₁ and R ₂ are an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and an aliphatic hydrocarbon group. It is selected from aromatic hydrocarbon groups substituted with a group or alicyclic hydrocarbon group. R ₁ and R ₂ may be the same hydrocarbon group or different hydrocarbon groups. The carbon number of R ₁ and R ₂ is not particularly limited, but is usually 1 to 8 (more preferably 1 to 4). The type of R'is not particularly limited, but is usually an alkylene group having 1 to 4 carbon atoms. Specific examples of the aminoalkyl alcohol represented by the above general formula include dimethylaminoethanol, diethylaminoethanol, di-n-propylaminoethanol, di-n-butylaminoethanol, diethylamino-n-propanol, dibenzylaminoethanol and methylethylamino. There is ethanol etc.

In the reaction solution of the present invention, an "azeotropic agent" which is sparingly soluble in methanol and forms a minimum azeotropic mixture with methanol is present in a conventional manner. This azeotropic agent is used to quickly distill off the methanol generated by the reaction from the reaction solution. Preferred "azeotropic agents" include n-pentane, n-hexane, n-heptane, n-
There are octane, 2,5-dimethylhexane, 2,2,4-trimethylpentane, 2-methylpentane, 3-methylpentane and the like. Among them, it is particularly preferable to use n-hexane because the proportion of methanol in the azeotropic mixture is high.

Examples of the above-mentioned "Michael adduct" include methyl (meth) acrylate / methanol Michael adduct (A), methyl (meth) acrylate / aminoalkyl alcohol Michael adduct (B), aminoalkyl (meth) acrylate. / Methanol Michael adduct (C),
Aminoalkyl (meth) acrylate / aminoalkyl alcohol Michael adduct (D) may be mentioned. Of these, since the effect of increasing the yield of the target product is large,
It is preferable to use one or more Michael adducts selected from the above (B), (C), and (D).

This Michael adduct is an unreacted raw material and a residual liquid after distilling the above-mentioned aminoalkyl (meth) acrylate in the reaction liquid and introducing the first bottom liquid containing the above-mentioned Michael adduct. Obtained by introducing a second bottom liquid which is a residual liquid after distilling the above aminoalkyl (meth) acrylate and contains the above Michael adduct, or by distilling the first bottom liquid or the second bottom liquid. In addition, the distillate containing the above Michael adduct is introduced into the reaction liquid by any one or two or more methods. In addition, the above-mentioned Michael adduct synthesized or by-produced in another reaction system may be introduced into the reaction solution. In the present invention, it is particularly preferable to use the above method. This is efficient because the above method recycles the above-mentioned Michael adduct generated in the manufacturing process, and also prevents sludge generated from a catalyst or the like, a polymer obtained by polymerizing raw materials, or the like from being introduced into the reaction liquid. Because it is done.

The above-mentioned Michael adduct has a concentration of the Michael adduct of 0.5 to 10% in the reaction liquid, based on the total amount of the charged raw materials of methyl (meth) acrylate and aminoalkyl alcohol. 0 wt% (preferably 1.0-5.0 wt%, more preferably 2.0-
It is preferable to introduce it into the reaction solution so that the concentration becomes 4.0 wt%). This is because the desirable lower limit of the concentration of the above Michael adduct in the reaction solution is 0.5 wt%,
This is because if it is less than this concentration, the effect of suppressing the Michael addition reaction is small, and the yield of the target product, aminoalkyl (meth) acrylate, becomes insufficient. Further, the desirable upper limit of the concentration of the above-mentioned Michael adduct is set to 10.0 wt% because the Michael addition reaction can be sufficiently suppressed even at this concentration or less, and if the concentration of the above-mentioned Michael adduct is increased to more than 10.0 wt%. This is because there is a possibility that the production efficiency may be lowered.

In the method for producing aminoalkyl (meth) acrylate of the present invention, a Michael adduct of methyl (meth) acrylate and amino alcohol or methanol, and / or aminoalkyl (meth) acrylate and amino alcohol or methanol are used. Michael adduct of is introduced into the reaction solution. Therefore, since the Michael addition reaction is suppressed, the target product aminoalkyl (meth) is
Acrylate can be obtained in high yield. The Michael adduct is contained in the residual liquid (can liquid) obtained by distilling the aminoalkyl acrylate or the like or the distillate obtained by distilling the residual liquid. Therefore, if this liquid is introduced into the reaction liquid, the Michael addition reaction is suppressed and the residual liquid and the like are effectively used. Further, the presence of an azeotropic agent in the reaction solution allows the methanol to be distilled off quickly. This further suppresses the formation of the above-mentioned Michael adducts of A and C, so that the yield of aminoalkyl (meth) acrylate can be further improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to examples. (1) Effect of use of Michael adduct and azeotropic agent on yield (Example) This example is an example in which both the azeotropic agent and the Michael adduct are used. To a three-necked flask equipped with a fractionation tower and a distiller, methyl methacrylate, dimethylaminoethanol, phenothiazine, magnesium dimethylaminoethylate, n-hexane and a high boiling Michael adduct were added at the following composition ratio and heated. . Methyl methacrylate 200.0 parts by weight Dimethylaminoethanol 89.0 parts by weight Phenothiazine 0.28 parts by weight Magnesium dimethylaminoethylate 1.1 parts by weight n-Hexane 30.0 parts by weight High boiling Michael adduct 9.0 parts by weight

Here, phenothiazine is used as a polymerization inhibitor, magnesium dimethylaminoethylate which is an alkaline earth metal alcoholate is used as a catalyst for transesterification, and n-hexane is used as an azeotropic agent with by-produced methanol. Further, this "high boiling Michael adduct" is produced by the Michael addition reaction of (M1) methyl methacrylate and amino alcohol, (M2) dimethylaminoethyl methacrylate and methanol, (M3) dimethylaminoethyl methacrylate and amino alcohol, respectively. And a mixture of Michael adducts (B, C and D above). The concentration of the high boiling Michael adduct in the above composition is 2.7 wt%. n
-Hexane was refluxed as a reflux liquid, the overhead temperature of the fractionating tower was maintained at 49 to 51 ° C, and the reaction was carried out for 4 hours while distilling the methanol / n-hexane azeotrope to obtain a reaction liquid. It was

Comparative Example 1 Comparative Example 1 is an example in which neither the azeotropic agent nor the Michael adduct is used. To a three-necked flask equipped with a fractionation tower and a distiller, methyl methacrylate 200.0 parts by weight dimethylaminoethanol 89.0 parts by weight phenothiazine 0.28 parts by weight magnesium dimethylaminoethylate 1.1 parts by weight and heated. did. The overhead temperature of the fractionating tower was maintained at 64-66 ° C., and the reaction was carried out for 4 hours while distilling the methanol / methyl methacrylate azeotrope to obtain a reaction solution.

Comparative Example 2 This Comparative Example 2 is an example in which only the azeotropic agent is used and no Michael adduct is used. In a three-necked flask equipped with a fractionator and a distiller, methyl methacrylate 200.0 parts by weight dimethylaminoethanol 89.0 parts by weight phenothiazine 0.28 parts by weight magnesium dimethylaminoethylate 1.1 parts by weight n-hexane 30 0.0 parts by weight was added and heated. n-Hexane is destillated as a distillate, the overhead temperature of the fractionating column is maintained at 49 to 51 ° C., and the reaction is carried out for 4 hours while distilling a methanol / n-hexane azeotrope to obtain a reaction solution. It was

Comparative Example 3 Comparative Example 3 is an example in which only the Michael adduct is used and no azeotropic agent is used. Methyl methacrylate 200.0 parts by weight Dimethylaminoethanol 89.0 parts by weight Phenothiazine 0.28 parts by weight Magnesium dimethylaminoethylate 1.1 parts by weight High boiling Michael addition The product (9.0 parts by weight) was added and heated. Here, the composition of the high boiling Michael adduct used was the same as that of the example. The top temperature of the fractionator is 64
The reaction liquid was obtained by maintaining the temperature at ˜66 ° C. and reacting for 4 hours while distilling the methanol / methyl methacrylate azeotrope.

The reaction liquids obtained in Examples and Comparative Examples 1 to 3 were analyzed by gas chromatography, and the conversion C of dimethylaminoethanol was calculated from the following formula (1).
The yield Y of dimethylaminoethyl methacrylate was obtained from the following equation (2), and the selectivity S was obtained from the following equation (3). In the equations (1) to (3) below, "DMAE"
Is an abbreviation for “dimethylaminoethanol” and “DM” is an abbreviation for “dimethylaminoethyl methacrylate”. Conversion rate C (%) = [reacted DMAE (mol) / charged DMAE (mol)] x 100 (1) Yield Y (%) = [generated DM (mol) / charged DMAE (mol)] x 100 ( 2) Selectivity S (%) = [Yield Y (%) / Conversion rate C (%)] × 100 (3)

Table 1 shows the analysis results of the reaction solutions of Examples and Comparative Examples 1 to 3. Table 1 -------------------------------------- Azeotropic agent Michael conversion C yield Y selectivity S Adduct (%) (%) (%) -------------------------------- 95 92 97 Comparative Example 1 Not used Not used 96 87 91 Comparative Example 2 Used Not used 95 90 95 Comparative Example 3 Not used 96 96 91 95 −−−−−−−−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−

As can be seen from Table 1, comparing Comparative Example 1 in which neither the azeotropic agent nor the Michael adduct is used with the Example in which both the azeotropic agent and the Michael adduct are used, the conversion of dimethylaminoethanol Although the rates C are almost equal, the yield Y of dimethylaminoethyl methacrylate is improved by 5% and the selectivity S is improved by 6% in the examples. This is because the high-boiling Michael adduct is present in the reaction solution in the examples, so that the Michael addition reactions of (M1) to (M3) above are suppressed, and n-hexane is used as an azeotropic agent. Therefore, it is presumed that methanol was rapidly distilled off from the reaction solution, which further suppressed the above-mentioned Michael addition reaction of (M2) and improved the yield Y and the selectivity S of the target product. Further, in Comparative Example 2 using only the azeotropic agent and no Michael adduct, and Comparative Example 3 using only the Michael adduct and no azeotropic agent, dimethylaminoethanol was compared to Comparative Example 1. Although the conversion rates C are almost equal, the yields Y are improved by 3% and 4%, respectively, and the selectivity S is improved by 4%. However, in the examples, the yield Y and the selectivity S are further improved, which is considered to be due to the synergistic effect of using the azeotropic agent and the Michael adduct together.

From the above results, the presence of the high boiling Michael adduct and the azeotropic agent in the reaction solution makes it possible to obtain dimethylamino with a high yield and a high selectivity using a relatively inexpensive alkaline earth metal alcoholate as a catalyst. It turns out that ethyl methacrylate can be synthesized.

(2) Application to manufacturing process An example of a manufacturing process of dimethylaminoethyl methacrylate to which the manufacturing method of the present invention is applied is shown in FIG. That is,
Methyl methacrylate, dimethylaminoethanol, magnesium dimethylaminoethylate as a catalyst, and n-hexane as an azeotropic agent are added to the reaction vessel 1 and heated. While trans-producing methanol as an azeotrope of n-hexane from the upper part of the reaction kettle 1, the transesterification reaction between methyl methacrylate and dimethylaminoethanol proceeds. At this time, in the reaction kettle 1, a high boiling Michael adduct is produced by the Michael adduct of (M1) to (M3) together with the Michael adduct of methyl methacrylate and methanol.

The obtained reaction liquid is withdrawn from the bottom of the reaction kettle 1 and sent to a rectification column 2 for removing unreacted raw materials through a conduit 11. In this rectification column 2 for removing unreacted raw materials, a Michael adduct of methyl methacrylate and methanol was distilled from the top of the column together with unreacted methyl methacrylate, dimethylaminoethanol and n-hexane. Are returned to the reaction kettle 1. Fractionation tower for removing unreacted raw materials 2
The residue at the bottom of the column contains the high boiling Michael adduct together with the target product. This residue is sent to the rectification column 3 for ester distillation via a conduit 21. Then, a purified product of dimethylaminoethyl methacrylate, which is a target substance, is obtained from the top of the rectification column 3 for ester distillation.

On the other hand, the residue at the bottom of the ester distillation rectification column 3 contains a high boiling Michael adduct together with the target product which could not be distilled off from the top of the ester distillation rectification column 3. . This residue is sent to the Michael adduct recovery rectification column 10 via a conduit 31 and heated to distill the high boiling Michael adduct from the top of the tower, and the high boiling Michael adduct is introduced into the conduit 10.
Return from 1 to reaction kettle 1. At this time, the total concentration of the above-mentioned four types (A to D) of the Michael adduct in the reaction liquid in the reaction kettle 1 is 0.5 wt% to 10.0 wt% (preferably 2.0 wt% to 4.0 wt%). So that the reaction kettle 1
Adjust the amount of Michael adducts returned to.

According to the present manufacturing process, the high boiling Michael adduct obtained by distilling the residue at the bottom of the rectification column for ester distillation 3 is returned to the reaction kettle 1 so that the Michael addition reaction in the reaction kettle 1 is performed. Is suppressed, which has the effect of improving the yield of the target substance. Since this high boiling Michael adduct is recycled, its impact on manufacturing costs is minimal. Further, by using n-hexane as an azeotropic agent, the by-product methanol in the reaction kettle 1 is n
-Since it is rapidly distilled off as an azeotrope with hexane, the Michael addition reaction between methanol and methyl methacrylate or dimethylaminoethyl methacrylate is suppressed, so that the yield of the target product is further improved.

Further, the method of the present invention is not particularly limited as a catalyst used in the production process to a metal alcoholate such as magnesium dimethylaminoethylate used in the present production process, but is particularly effective in a reaction system using a metal alcoholate as a catalyst. is there. Preferred metal alcoholates include those in which the metal is an alkaline earth metal such as magnesium or an alkali metal such as potassium or sodium, and the alkoxy group is an ethyl group, a propyl group, a butyl group, a dimethylamino group or the like. This has been a problem that a Michael adduct is easily generated when a metal alcoholate catalyst is used, but the application of the present invention can suppress the formation of the Michael adduct even when a metal alcoholate catalyst is used. This is because. Further, the Michael addition product generated in the present production process is recycled to the reaction kettle 1 and is effectively utilized to suppress the Michael addition reaction in the reaction solution.

According to the present production process, by recycling n-hexane as an azeotropic agent as follows, this azeotropic agent can be used energetically advantageously. That is, the distillate from the upper part of the reaction kettle 1 containing n-hexane and methanol is sent to a low boiling point removal rectification column 4 through a conduit 12 to obtain a high boiling point content containing unreacted raw materials and target substances. It is divided into a low boiling point content mainly consisting of an azeotropic mixture of methanol and hexane. The high boiling point is returned from the bottom of the low boiling point rectification column 4 to the reaction vessel 1 through the conduit 41, and the low boiling point is fed through the conduit 4
After 2 were feed condensed in the first condenser 5, and sends via line 51 to the separator 6. This low-boiling component is contained as an impurity in dimethylaminoethanol as a raw material, or during an ester exchange reaction, an amine compound such as trimethylamine produced as a by-product from an aminoalkyl alcohol (hereinafter,
(Abbreviated as "amine compound") is included. The inside of the separator 6 is kept at about 10 ° C., where the low boiling point is mainly composed of n-hexane (hereinafter referred to as “azeotropic agent layer”) and the lower layer mainly composed of methanol (hereinafter referred to as “azeotropic agent layer”). And "methanol layer"). At this time, most of the amine compound is contained in the methanol layer. The azeotropic agent layer is
It is returned from the conduit 61 to the low boiling point rectification column 4 for recycling.

On the other hand, the methanol layer is made to flow through the ion exchange column 7 filled with the cation exchange resin via the conduit 62 to adsorb and remove the amine compound contained in the methanol layer, and then to remove the amine removing liquid. It is sent from the conduit 71 to the azeotropic agent removing rectification column 8. After distilling n-hexane contained in the amine removing liquid together with methanol from the top of the azeotropic agent removing rectifying column 8, the distillate is sent from the conduit 81 to the second condenser 9 to be condensed, It is returned to the separator 6 by the conduit 91 and recycled. The methanol remaining in the azeotropic agent removing rectification column 8 is withdrawn from the system through the bottom of the column.

The reason why the amine compound is removed from the methanol layer is to prevent the amine compound from being concentrated when n-hexane contained in the methanol layer is recycled. When the concentration of the amine compound in the separator 6 becomes high, the temperature at which the two layers can be separated is lowered, which requires cooling to perform the two-layer separation, which is not preferable in terms of energy. According to this manufacturing process,
Since the amine compound in the methanol layer is removed in the ion exchanger 7, the concentration of the amine compound is suppressed even if n-hexane is recycled. Therefore, the low boiling point component from the top of the low boiling point removing rectification column 4 can be continuously separated into two layers in the separator 6 at about 10 ° C. which is a temperature close to room temperature. As a result, the energy required for cooling the separator 6 can be saved, so that the azeotropic agent can be recovered with energy efficiency and recycled.

The present invention is not limited to the specific embodiments described above, but may be variously modified within the scope of the present invention in accordance with the purpose and application. For example, in the above manufacturing process, the high boiling Michael adduct is returned to the reaction kettle 1 as the distillate from the top of the Michael adduct recovery rectification column 10. The residue at the bottom of the column (corresponding to the “first bottom liquid” in the claims) may be returned to the reaction kettle 1. When the unreacted raw material removal rectification column 2 in FIG. 1 is a rectification column for distilling the unreacted raw material and the target product, the residue at the bottom of the unreacted raw material removal rectification column 2 (Corresponding to the “second can liquid” described in the claims) may be returned to the reaction kettle 1. Furthermore, two or more of the distillate from the top of the rectification column 10 for recovering Michael adduct, the first bottom liquid, the second bottom liquid, and the distillate of the second bottom liquid are used in the reaction kettle 1. May be returned to.

In the above manufacturing process, the composition ratio of each Michael adduct of the high boiling Michael adducts returned to the reaction kettle 1 is not particularly limited, but the ratio of the above B, C and D Michael adducts is increased. It is preferable. Also, by allowing one or two kinds of adducts selected from these Michael adducts to be present in the reaction solution, the effect of suppressing the Michael addition reaction in the reaction solution can be similarly obtained.

In the above examples, the case of producing dimethylaminoethyl methacrylate from methyl methacrylate as a raw material has been described. However, according to the production method of the present invention, even in the case of producing dimethylaminoacrylate from methyl acrylate as a raw material. The same effect can be obtained. That is, by adding a high boiling Michael adduct to the reaction solution and using an azeotropic agent, magnesium dimethylaminoethylate, which is a relatively inexpensive catalyst, can be used to obtain a high yield of the target product, dimethylaminoacrylate. Can be manufactured in. Further, in the above-mentioned examples, the case of producing an aminoalkyl (meth) acrylate by using magnesium dimethylaminoethylate which is an alkaline earth metal alcoholate as a catalyst has been described, but according to the production method of the present invention, an alkali metal alcoholate or other Similarly, when a metal alcoholate is used as a catalyst, aminoalkyl (meth) acrylate can be produced in high yield. Further, the present invention may be applied to a system using a catalyst other than metal alcoholate.

When recycling n-hexane as an azeotropic agent, the ion exchanger 7 is used in the manufacturing process shown in FIG.
Is provided between the separator 6 and the azeotropic agent removing rectification column 8, but the ion exchanger 7 may be provided in the conduit 91. Also in this case, since the amine compound is removed when recycling the n-hexane recovered from the methanol layer, the concentration of the amine compound is suppressed.

Further, the ion exchanger 7 may be provided in the conduit 61 which is a pipe for returning the azeotropic agent layer to the rectification column 4 for removing low boiling substances. Since the amine compound is also contained in the azeotropic agent layer at a predetermined distribution rate, the concentration of the amine compound is suppressed by recycling the azeotropic agent while adsorbing and removing the amine compound in the azeotropic agent layer. In particular, aminoalkyl alcohols containing an amine compound having a higher compatibility with an azeotropic agent, such as an alkyl group higher than a methyl group (eg, propyl group, butyl group, benzyl group, etc.), as a raw material In the case of producing (meth) acrylate, it is preferable to provide the ion exchanger 7 at this position because the amine compound derived from these aminoalkyl alcohols is more likely to be concentrated.

Further, by providing the ion exchanger 7 in the conduit 51, the concentration of the amine compound in the liquid supplied to the separator 6 is reduced. In this case, there is an effect that good two-layer separability can be obtained in the separator 6 regardless of whether or not the azeotropic agent is collected and recycled. Further, the ion exchanger 7 may be provided at a plurality of locations among the above locations.

[0037]

According to the method for producing an aminoalkyl (meth) acrylate of the present invention, in the presence of a specific azeotropic agent,
Furthermore, by allowing a Michael adduct of alkyl (meth) acrylate and amino alcohol or methanol and / or a Michael adduct of aminoalkyl (meth) acrylate and amino alcohol or methanol to exist in the reaction liquid, The Michael addition reaction in the inside can be suppressed. This improves the yield of aminoalkyl (meth) acrylate. Further, if a residual liquid (can liquid) obtained by distilling the above aminoalkyl acrylate or the like or a distillate obtained by distilling this residual liquid (containing the above Michael adduct) is used, The reaction is suppressed and the residual liquid is effectively used, which is very useful from the viewpoint of the entire reaction system.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a manufacturing process of dimethylaminomethacrylate to which the manufacturing method of the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Reactor, 2; Fractionation column for removing unreacted raw materials, 3; Fractionation column for ester distillation, 4; Fractionation column for removing low-boiling substances, 6; Separator, 7; Ion exchanger, 8; Fractionator for removing boiling agent, 1
0: Fractionation tower for recovering Michael adduct.

Claims (2)

[Claims] 1. An aminoalkyl acrylate (c) is obtained by a transesterification reaction in which a reaction solution comprising methyl acrylate (a) or methyl methacrylate (b) and an aminoalkyl alcohol represented by the following general formula is heated.
Alternatively, in the method for producing aminoalkyl methacrylate (d), an azeotropic agent which is hardly soluble in methanol and forms a minimum azeotropic mixture with methanol is present in this reaction solution, and each ester compound (a ), (B), (c) or (d) and a Michael adduct of amino alcohol or methanol are introduced, a method for producing an aminoalkyl (meth) acrylate. [General Formula] R ₁ R ₂ N—R′—OH where R ₁ is a hydrocarbon group, R ₂ is a hydrocarbon group, and R ′ is an alkylene group. 2. A residual liquid after distilling the aminoalkyl acrylate or the aminoalkyl methacrylate from the transesterification reaction product liquid of the (a) or (b) and the aminoalkyl alcohol in the reaction liquid. And a first can liquid containing the above-mentioned Michael addition product,
A second bottom liquid, which is a residual liquid after the unreacted raw material and the above aminoalkyl acrylate or the above aminoalkyl methacrylate is distilled from the above reaction product liquid, and contains the above Michael adduct, or the above first can liquid or the above The method for producing an aminoalkyl (meth) acrylate according to claim 1, wherein a distillate containing the Michael adduct, which is obtained by distilling the two-can solution, is introduced.