JP3446469B2 - Method for recovering azeotropic agent in production of aminoalkyl (meth) acrylate - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the recovery of an azeotropic agent in the production of aminoalkyl acrylate or aminoalkyl methacrylate using a transesterification reaction (hereinafter, the actrate and the methacrylate are collectively referred to as “(meth) acrylate”). More specifically, the present invention relates to a method for recovering an azeotropic agent by efficiently recovering the azeotropic agent by improving the two-layer separability of an azeotropic mixture containing by-product methanol and an azeotrope during reaction. INDUSTRIAL APPLICATION This invention is utilized for the manufacturing method of dimethylaminoethyl (meth) acrylate. Incidentally, the aminoalkyl group in the aminoalkyl (meth) acrylate in the present specification means
A di-substituted aminoalkyl group having two hydrocarbon groups.

[0002]

2. Description of the Related Art A method for producing an aminoalkyl (meth) acrylate by a transesterification reaction is already known. For example, when methyl (meth) acrylate and dimethylaminoethanol are used as raw materials, the products dimethylaminoethyl (meth) acrylate and methanol are produced by the transesterification reaction between them. Since this transesterification reaction is an equilibrium reaction, it is necessary to quickly distill the produced methanol out of the system in order to proceed the reaction.

JP-A-2-17155 discloses that at least one β-diketone zinc compound is used as a catalyst,
A method for producing an aminoalkyl (meth) acrylate by reacting an alkyl (meth) acrylate with a dialkylaminoalkyl alcohol is disclosed. In the examples of the above publications, the produced methanol is n-
It is described that the reaction proceeds while being extracted as an azeotropic mixture with hexane from the system.

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.

[0005]

However, in the production of aminoalkyl (meth) acrylate by transesterification, if the azeotropic mixture is separated into two layers and the azeotropic agent is recovered and reused, the degree of reuse increases. As a result, the phenomenon that the azeotropic mixture does not separate into two layers is observed. Therefore, it is necessary to cool the azeotropic mixture to a considerably low temperature in order to improve the two-layer separation property, which is an energy disadvantage. The present invention overcomes the above drawbacks,
In the production of aminoalkyl (meth) acrylate,
It is an object to provide a method for efficiently recovering an azeotropic agent.

[0006]

Means for Solving the Problems The present inventors have found that aminoalkyl alcohols, which are raw materials for aminoalkyl (meth) acrylates, may contain amine compounds such as trialkylamines as impurities. Further, in some cases, attention was paid to the fact that an amine compound was by-produced from an aminoalkyl alcohol in the transesterification reaction.
The present invention has been completed by finding that the concentration of the amine compound present in the azeotrope affects the two-layer separability of the azeotrope.

A method for recovering an azeotropic agent in the production of aminoalkyl (meth) acrylate according to the first aspect of the present invention (hereinafter simply referred to as "method for recovering azeotropic agent" or "main recovery method").
Is a methyl (meth) acrylate and a general formula (1) shown below while recycling the azeotropic agent in the presence of an azeotropic agent that is sparingly soluble in methanol and forms a minimum azeotropic compound with the methanol. ) And a method for recovering an azeotropic agent in the production of an aminoalkyl (meth) acrylate by transesterification with an aminoalkyl alcohol containing an amine compound as an impurity, the method comprising: Then, the azeotropic mixture is cooled to separate the methanol layer and the azeotropic agent layer, and then (1) the aminoalkyl alcohol contained in the methanol layer liquid. Is removed by adsorption, and then the azeotropic agent is recovered from the amine removing solution, or (2) the azeotropic agent contained in the methanol layer solution is recovered. And, thereafter, the recovered co the amine compound contained in the boiling agent was removed by adsorption and then, characterized by recycling the recovered azeotropic agent obtained by the above (1) or (2).

For the amine compound contained in the methanol layer liquid, the methanol compound may be taken out from the [1] separator or the like, and the amine compound may be adsorbed and removed from the methanol layer liquid, or the [2] separator or the like. It is also possible to distill the methanol layer liquid extracted from the above to distill off the azeotropic agent as an azeotropic mixture with methanol, and to adsorb and remove the amine compound after cooling and condensing the distillate.

The method for recovering the azeotropic agent of the second invention is as follows:
In the presence of an azeotropic agent which is sparingly soluble in methanol and forms a minimum azeotropic compound with the methanol, an aminoalkyl (meth) is formed by a transesterification reaction while recycling the azeotropic agent.
A method for recovering an azeotropic agent in producing an acrylate, wherein an azeotropic mixture comprising the methanol and the azeotropic agent is distilled off, and then the aminoalkyl alcohol contained in the distillate. The amine compound derived from is removed by adsorption, then the distillate after the removal of the amine is separated into a methanol layer and an azeotropic agent layer, and the azeotropic agent layer solution is separated from the methanol layer solution and the azeotropic agent layer solution. It is characterized in that the boiling agent is recovered.

The removal of the amine compound by adsorption can be carried out after the distilling azeotropic mixture is cooled and condensed and before the two layers are separated. The method for recovering the azeotropic agent according to the second aspect of the present invention can be used both when the azeotropic agent is recycled and when it is stopped after some recycling.

The method of recovering the azeotropic agent of the third invention is as follows.
In the presence of an azeotropic agent which is sparingly soluble in methanol and forms a minimum azeotropic compound with the methanol, an aminoalkyl (meth) is formed by a transesterification reaction while recycling the azeotropic agent.
A method for recovering an azeotropic agent in producing an acrylate, comprising distilling an azeotropic mixture comprising the methanol and the azeotropic agent, and then cooling the azeotropic mixture to form a methanol layer and an azeotropic agent. It is characterized in that the layers are separated, then the amine compound derived from the aminoalkyl alcohol contained in the azeotropic agent layer liquid is removed by adsorption, and then the amine removal liquid is recycled. [General Formula] R ₁ R ₂ N—R′—OH (1) However, R ₁ is a hydrocarbon group, R ₂ is a hydrocarbon group, and R ′ is an alkylene group.

In the above general formula (1) representing the "aminoalkyl alcohol" in the present invention, R ₁ and R ₂ are respectively an aliphatic hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon. Group, and an aromatic hydrocarbon group substituted with an aliphatic or alicyclic hydrocarbon group, and the like. R ₁ and R ₂ may be the same hydrocarbon group,
It may be a different hydrocarbon group. The carbon number of R ₁ and R ₂ is not particularly limited, but it is preferably 1 to 8 (more preferably 1 to 4). This is R ₁ or R
_In the aminoalkyl alcohol having ₂ or less carbon atoms,
This is because the amine compound contained in the aminoalkyl alcohol as an impurity has a low boiling point, and is easily distilled together with the azeotropic mixture. 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 (1) include dimethylaminoethanol, diethylaminoethanol, di-n-propylaminoethanol, di-n-butylaminoethanol, dibenzylaminoethanol, methylethylaminoethanol, Examples include diethylamino n-propanol and diethylamino i-propanol.

The preferred "azeotropic agent" in the present invention
As, n-pentane, n-hexane, n-heptane, n-octane, 2,5-dimethylhexane, 2,
2,4-trimethylpentane, 2-methylpentane, 3
-Methyl pentane and the like. Among them, it is particularly preferable to use n-hexane because the proportion of methanol in the azeotropic mixture is high.

Typical examples of the above "amine compound" include:
Examples include compounds that are trialkylamines, dialkylamines, and monoalkylamines, where the alkyl group is methyl, ethyl, propyl, butyl, or the like. According to the present invention, the concentration of the amine compound in the azeotropic mixture before the separation of the methanol layer and the azeotropic agent layer is 0.2 wt% or less, more preferably 0.15 wt% by adsorbing and removing the amine compound. Or less, more preferably 0.05 wt
% Or less is preferable. As described above, by reducing the concentration of the amine compound, it becomes possible to separate the methanol layer and the azeotropic agent layer into two layers with high energy efficiency.

Examples of the method of adsorbing and removing the amine compound include a method of bringing a liquid containing an amine compound into contact with an ion exchanger. Although it is preferable to use an ion exchange resin as the ion exchanger, it is not limited to the resin, zirconium phosphate, titanium phosphate,
An inorganic ion exchanger such as montmorillonite may be used. As the ion exchange resin, H-type and sodium salt type non-aqueous strongly acidic ion exchange resins can be used. When a sodium salt type ion exchange resin is used, it is used after being acid-treated with hydrochloric acid, sulfuric acid or the like to be converted into the H type. When a wet type ion exchange resin is used, or when acid treatment is carried out in advance as described above, water is replaced with methanol before use. Specific examples of the ion exchange resin include trade names “Amberlite IR-122”, “Amberlite IR-124”, and “Amberlite IR-2” manufactured by Rohm & Haas.
00C "," Amberlite IR-200CT "," Amberlite IR-200CP ", and product names" Amberlist 15 "," Amberlist 16 "manufactured by the same company.
"Amberlyst 18" or product name "Levatit SP112", "Levatit S" manufactured by Farbenfabrik Bayer
P120 "or the like can be used.

According to the method for recovering an azeotropic agent of the first invention,
(1) The amine compound contained in the methanol layer solution obtained by separating the azeotropic mixture into two layers is removed by adsorption, and then the azeotropic agent is recovered from the amine removal solution, or (2) The azeotropic agent contained in the methanol layer solution is recovered, then the amine compound contained in the recovered azeotropic agent is removed by adsorption, and then the recovered azeotropic agent obtained in (1) or (2) above is recovered. Recycle the effervescent. Since the amine compound is removed from the recycled azeotropic agent, the concentration of the amine compound in the azeotropic mixture is prevented or suppressed. This allows the azeotropic mixture to reach a temperature close to room temperature, for example 5 to 10 ° C., until the end of the transesterification reaction.
Since it is possible to separate the two layers, the azeotropic agent can be energy-efficiently recovered and recycled.

According to the method for recovering an azeotropic agent of the second invention,
The amine compound contained in the distillate consisting of the azeotropic mixture is removed by adsorption, and then the distillate after removal of the amine is separated into two layers, a methanol layer and an azeotropic agent layer, and the methanol layer solution and The azeotropic agent is recovered from at least one of the azeotropic agent layer liquids. According to this method, even when the distillate contains an amount of an amine compound that hinders easy two-layer separation, the two-layer separation is performed after removing the amine compound in the distillate. Temperature close to, for example 5-10 ° C
The distillate can be separated into two layers. Therefore, the azeotropic agent can be efficiently recovered from at least one of the methanol layer liquid and the azeotropic agent layer liquid.

According to the method for recovering an azeotropic agent of the third invention,
The amine compound contained in the azeotropic agent layer liquid obtained by separating the azeotropic mixture into two layers is removed by adsorption, and then the amine removal liquid is recycled. Since the amine compound is removed from the recycled azeotropic agent, the concentration of the amine compound in the azeotropic mixture is prevented or suppressed. This allows the azeotropic mixture to be separated into two layers at a temperature close to room temperature, for example, 5 to 10 ° C., until the end of the transesterification reaction, as in the method for recovering an azeotropic agent of the first invention. Therefore, the azeotropic agent can be recovered with energy efficiency and recycled.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to Examples. First, the relationship between the amine compound concentration and the two-layer separation temperature will be described. Assuming a case where dimethylaminoethyl methacrylate is produced by transesterification of dimethylaminoethanol and methyl methacrylate using n-hexane as an azeotropic agent, the relationship between the concentration of the amine compound in the azeotropic mixture and the two-layer separation temperature is assumed. Examined. Dimethylaminoethanol usually contains tens to hundreds of ppm of trimethylamine. By recycling the azeotropic agent, this trimethylamine reproduces the state of being concentrated in the azeotrope before the two-layer separation.
Trimethylamine was added to a mixture of hexane, methanol and methylmethacrylate at the concentrations shown in Table 1 below. Here, the reason why the mixture obtained by adding methyl methacrylate to the azeotrope is used is that the raw material methyl methacrylate is distilled out together with the azeotrope in the actual production.

While the experimental temperature was raised from -10 ° C at intervals of 5 ° C, each sample was thoroughly stirred and then allowed to stand, and the separated state was visually evaluated. In Table 1, "separation temperature" indicates the maximum temperature at which clear separation was obtained. Where "clear separation"
The term "is a state in which it is possible to visually confirm that the upper layer and the lower layer form a clear separation interface immediately after standing, without forming an intermediate layer.

[0021]

[Table 1]

From Table 1, the trimethylamine concentration is 0.2
3% (Experiment No. 6) or 0.50 wt% (Experiment No. 6)
In 7), the sample could not be separated into two layers unless it was cooled to -5 ° C or lower. On the other hand, when the trimethylamine concentration is 0.15 wt% (Experiment No. 5) or less, 0
The sample can be separated into two layers well at 10 ° C.
The two-layer separation could be carried out at a temperature of 0 ° C without any problem in practical use. And the trimethylamine concentration is 0.05
At less than wt% (Experiment No. 3), as in the case where trimethylamine does not exist (Experiment No. 1), two-layer separation can be clearly performed at 10 ° C., which is a temperature close to room temperature, resulting in very good separation. Sex was obtained.

As can be seen from the above results, the two-layer separation property improves as the trimethylamine concentration decreases, and in order to perform the two-layer separation at a temperature close to room temperature, 10 ° C., trimethylamine in the liquid before the separation. 0.20w concentration
t% or less is preferable, 0.15 wt% or less is more preferable, and 0.05 wt% or less is further preferable.

Next, the operation of removing the amine compound with the ion exchange resin will be specifically described. "Amberlite IR-200C" as ion exchange resin (ROHM &
(Manufactured by Haas Co., Ltd.), a sample of 500 ml having the following composition was subjected to adsorption treatment under the condition of SV = 6 by a column of 20 mmφ × 315 mm. n-Hexane 45.0 wt% Methanol 48.0 wt% Methyl methacrylate 5.0 wt% Trimethylamine 2.0 wt%

The trimethylamine concentration in the sample after the treatment was 1 ppm or less. Thus, it can be seen that the concentration of trimethylamine was reduced to a concentration at which the two layers could be separated at 10 ° C., which is a temperature close to room temperature, by adsorbing trimethylamine on the ion exchange resin.

Next, application to the manufacturing process will be described. An example of a manufacturing process of dimethylaminoethyl methacrylate to which this recovery method is applied is shown in FIG. That is, a catalyst such as methyl methacrylate, dimethylaminoethanol, an alkali or alkaline earth metal alcoholate, and n-hexane as an azeotropic agent are added to the reaction vessel 1 and heated. The transesterification reaction is allowed to proceed while distilling off by-produced methanol as an azeotropic mixture of n-hexane from the upper part of the reaction kettle 1. The obtained reaction solution is the reaction vessel 1
Is extracted from the bottom of the column and sent to the rectification column 2 via the conduit 11, and the rectification column 2 removes low-boiling components such as unreacted raw materials and azeotropic agents from the top of the column, and then rectifies from the bottom of the column with the conduit Tower 3
The purified product of dimethylaminoethyl methacrylate, which is the target substance, is obtained from the top of the rectification column 3.

Then, the distillate containing n-hexane and methanol from the upper part of the reaction kettle 1 is treated as follows. That is, this distillate is first sent to the low boiling point removal rectification column 4 via the conduit 12, and the low boiling point removal rectification column 4 uses the high boiling point component containing unreacted raw materials and the target substance and mainly methanol. And n-
It is divided into a low-boiling component consisting of an azeotropic mixture with hexane. The high boiling point is returned to the reaction vessel 1 from the bottom of the low boiling point rectification column 4 by a conduit 41. Further, the low boiling point fraction distilled from the top of the low boiling point removal rectification column 4 is sent from the conduit 42 to the first condenser 5 for condensation, and further from the conduit 51 to the separator 6.
Sent to. This low boiling point content contains trimethylamine derived from dimethylaminoethanol as a raw material.
The inside of the separator 6 is maintained at about 10 ° C., and the low boiling point fraction distilled from the top of the low boiling point removal rectification column 4 is mainly n− here.
An upper layer composed of hexane (hereinafter referred to as "azeotrope layer") and a lower layer composed mainly of methanol (hereinafter referred to as "methanol layer")
It is separated into two layers. At this time, most of trimethylamine is contained in the methanol layer. Then, the azeotropic agent layer is recycled by returning it from the conduit 61 to the low boiling point removal rectification column 4 as a reflux liquid.

On the other hand, the methanol layer is sent from the conduit 62 to the ion exchange column 7 filled with the cation exchange resin "Amberlite IR-200C" (manufactured by Rohm & Haas). While the methanol layer supplied from the conduit 62 flows through the ion exchanger 7, trimethylamine contained in this methanol layer is adsorbed and removed. The methanol layer flowing out from the ion exchanger 7, that is, the amine removing liquid, is sent to the azeotropic agent removing rectification column 8 through the conduit 71. Since this amine removing liquid contains n-hexane, n-hexane is distilled off from the top of the azeotropic agent removing rectification column 8 as an azeotropic mixture with methanol and recovered. The distillate from the top of the column is sent to the second condenser 5 by the conduit 81, condensed by the second condenser 5, and then returned from the conduit 91 to the separator 6. Then, with the azeotrope introduced through the conduit 51, two layers are separated again in the separator 6, and the upper azeotropic agent layer is recycled as a reflux liquid. Further, methanol is extracted from the bottom of the azeotropic agent removing fractionator 8 to the outside of the system. The destination of returning the reflux liquid is preferably the low boiling point removal rectification column 4 like the conduit 61 in the present embodiment. This is because methanol is contained in the reflux liquid, and therefore when the reflux liquid is returned to the reaction kettle 1, there is a risk that the progress of the transesterification reaction may be hindered.

In this way, n-hexane as an azeotropic agent is recovered and recycled. Since trimethylamine in the methanol layer is removed in the ion exchanger 7, the concentration of trimethylamine 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 examples described above, and various modifications may be made within the scope of the present invention according to the purpose and application. For example, in the manufacturing process shown in FIG. 1, the ion exchanger 7 is provided between the separator 6 and the azeotropic agent removing rectification column 8, but according to the present invention, the ion exchanger 7 may be provided in the conduit 91. Good. Also in this case, trimethylamine is removed when recycling the n-hexane recovered from the methanol layer, so that the concentration of trimethylamine 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 trimethylamine is also contained in the azeotropic agent layer at a predetermined distribution rate, the concentration of trimethylamine is suppressed by recycling the azeotropic agent while adsorbing and removing trimethylamine in the azeotropic agent layer. In particular, as an impurity, an amine compound such as an alkyl group higher than a methyl group (eg, propyl group, butyl group, benzyl group, etc.), which is considered to have higher compatibility with an azeotropic agent than trimethylamine, etc., is included. When amino (meth) acrylate is produced from aminoalkyl alcohol as a raw material,
Since these amine compounds are more likely to be concentrated, it is preferable to provide the ion exchanger 7 at this position.

Further, by providing the ion exchanger 7 in the conduit 51, the concentration of trimethylamine in the liquid supplied to the separator 6 is reduced. In this case, regardless of whether to continuously collect and recycle the azeotropic agent,
By applying the recovery method of the present invention, there is an effect that good two-layer separability can be obtained in the separator 6. Further, it is possible to provide the ion exchanger 7 at a plurality of locations among the above locations. Here, in the two-layer separation of the azeotropic mixture, since the amine compound is mainly contained in the methanol layer, a particularly preferable arrangement of the ion exchanger 7 is to allow the amine compound to be efficiently adsorbed and removed. Separator 6
This is a pipe downstream of the methanol outlet of the above, and the most preferable arrangement is between the separator 6 and the azeotropic agent removing rectification column 8. This is because the concentration of the amine compound in the methanol layer passing through the ion exchanger 7 is usually at a level most suitable for the adsorption treatment.

In the manufacturing process shown in FIG. 1, trimethylamine is always removed by the ion exchanger 7. However, when the trimethylamine concentration in the separator 6 becomes high to some extent, batch processing is performed to remove trimethylamine. May be removed. Also in this case, if the trimethylamine concentration in the separator 6 is always kept at 0.2 wt% or less, preferably 0.15 wt% or less, and more preferably 0.05 wt% or less, the azeotropic agent is recovered with energy efficiency. can do.

In the above-mentioned embodiment, the case of producing dimethylaminoethyl methacrylate from methyl methacrylate was explained, but according to the present recovery method, the same applies to the case of producing dimethylaminoethyl acrylate from methyl acrylate as a raw material. The above effect is obtained, that is, the amine compound is adsorbed and removed to reduce the concentration of trimethylamine in the azeotropic mixture before the two-layer separation, whereby the azeotropic agent can be recovered with energy efficiency. Further, the relationship between the amine compound concentration and the two-layer separation temperature is not limited to the composition shown in Table 1, for example, methanol 20 to 30 wt%, methyl methacrylate 2 to 5 wt.
%, And when trimethylamine was added to a liquid consisting of the balance of n-hexane, similar to the experimental results shown in Table 1,
It was observed that the separation temperature increased as the concentration of trimethylamine decreased.

[0035]

According to the method for recovering an azeotropic agent of the present invention, the concentration of the amine compound can be reduced by adsorbing the amine compound in the azeotropic mixture. As a result, the azeotropic mixture can be separated into two layers at a temperature close to room temperature, for example, 5 to 10 ° C. until the end of the transesterification reaction, so that the azeotropic agent can be recovered with energy efficiency. .

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a manufacturing process of dimethylaminoethyl methacrylate to which the present recovery method is applied.

[Explanation of Codes] 1; Reactor, 4; Fractionator for removing low-boiling substances, 5; First condenser, 6; Separator, 7; Ion exchanger, 8; Fractionator for removing azeotropic agent, 9; Second condenser.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-3-118352 (JP, A) JP-A-2-17155 (JP, A) JP-A-57-24336 (JP, A) JP-A-53- 141214 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C07C 213/06 C07C 213/10 C07C 219/08

Claims (3)

(57) [Claims] 1. In the presence of an azeotropic agent that is sparingly soluble in methanol and forms a minimum azeotropic compound with the methanol, methyl acrylate or methyl methacrylate, as shown below, while recycling the azeotropic agent: In the method of recovering an azeotropic agent in producing an aminoalkyl acrylate or aminoalkyl methacrylate by transesterification with an aminoalkyl alcohol represented by the general formula, an azeotropic mixture consisting of the methanol and the azeotropic agent is distilled. Then, the azeotropic mixture is cooled to separate the methanol layer and the azeotropic agent layer, and then (1) the amine compound derived from the aminoalkyl alcohol contained in the methanol layer liquid It is removed by adsorption, and then the azeotropic agent is recovered from the amine removal solution, or (2) it is contained in the methanol layer solution. The production of an aminoalkyl (meth) acrylate characterized by recovering the entraining agent, thereafter removing the amine compound contained in the recovering entraining agent by adsorption, and then recycling the recovered entraining agent. Method of recovering azeotropic agent in. [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. In the presence of an azeotropic agent which is sparingly soluble in methanol and forms a minimum azeotropic compound with the methanol, methyl acrylate or methyl methacrylate, as shown below, while recycling the azeotropic agent: In the method of recovering an azeotropic agent in producing an aminoalkyl acrylate or aminoalkyl methacrylate by transesterification with an aminoalkyl alcohol represented by the general formula, an azeotropic mixture consisting of the methanol and the azeotropic agent is distilled. Then, the amine compound derived from the aminoalkyl alcohol contained in the distillate is removed by adsorption, and the distillate after the amine removal is separated into a methanol layer and an azeotropic agent layer. Amino acid characterized by separating and recovering the azeotropic agent from at least one of the methanol layer solution and the azeotropic agent layer solution. Alkyl (meth) method for recovering the azeotropic agent in the manufacture of 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. 3. In the presence of an azeotropic agent which is sparingly soluble in methanol and forms a minimum azeotropic compound with the methanol, methyl acrylate or methyl methacrylate, as shown below, while recycling the azeotropic agent: In the method of recovering an azeotropic agent in producing an aminoalkyl acrylate or aminoalkyl methacrylate by transesterification with an aminoalkyl alcohol represented by the general formula, an azeotropic mixture consisting of the methanol and the azeotropic agent is distilled. Then, the azeotropic mixture is cooled to separate into a methanol layer and an azeotropic agent layer, and then the amine compound derived from the aminoalkyl alcohol contained in the azeotropic agent layer liquid is adsorbed. Of the aminoalkyl (meth) acrylate, characterized in that the amine removal liquid is recycled. Method for recovering the azeotropic agent in concrete. [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.