JPH11246495A - Production of alkylamino (meth)acrylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject compound useful e.g. as a dyeability improving agent for fiber in high purity by separating and recovering by-produced alkyl alcohol, refluxing to a reactive distillation column and including a polymerization inhibitor in the refluxing liquid, thereby enabling stable distillation in high efficiency. SOLUTION: A compound of formula III is produced by reacting a compound (A) of formula I (R<1> is H or methyl; R<2> is a 1-4C alkyl) with a compound of formula II (R<4> is a 1-8C alkyl; R<3> is H or R<4> ; R<5> is a 1-4C alkylene) using a reactive distillation column (X). In the above process, the byproduced alkyl alcohol (B) is continuously discharged from the distillation column X together with the compound A, the distilled alcohol B is separated and recovered, at least a part of the alcohol B is refluxed to the distillation column X and the reactive distillation is carried out in a state containing an amine-based polymerization inhibitor (C) in the refluxing liquid. Preferably, the reactive distillation is carried out by charging the alcohol B to the refluxing line of the distillation column X or the top of a cooling apparatus in an amount corresponding to 10-200 ppm based on the column top distillate of the distillation column X.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an alkylaminoalkyl (meth) acrylate, and more particularly to a method for producing an alkylaminoalkyl (meth) acrylate by a transesterification reaction between an alkyl (meth) acrylate and an alkylamino alcohol. About the method.

[0002] Alkylamino (meth) acrylates are
It is useful as a dye-improving agent for fibers, an antistatic agent for plastics, a pigment dispersant in paints, an ultraviolet curing assistant, etc.
It is also useful as a raw material for a monomer such as a cationic polymer flocculant.

[0003]

2. Description of the Related Art As a method for producing an alkylamino (meth) acrylate, a method based on a transesterification reaction between an alkyl (meth) acrylate and an alkylamino alcohol is already known. When an alkylamino (meth) acrylate is synthesized by transesterification between an alkyl (meth) acrylate and an alkylamino alcohol, an alkali metal alcoholate, a magnesium alcoholate, a titanium alcoholate,
It is known to use tin compounds such as dibutyltin oxide or acetylacetone metal complex compounds such as acetylacetone. Since this reaction has high polymerizability, charging of a polymerization inhibitor and blowing of an oxygen-containing gas are also used for the purpose of suppressing polymerization. Commonly used polymerization inhibitors include hydroquinone monomethyl ether,
Phenothiazine, substituted phenothiazine and the like,
As the oxygen-containing gas, JP-A-3-112949 discloses that if the distillation atmosphere is distilled in air or a 5% oxygen / nitrogen atmosphere after removing the catalyst, the polymerization in the distillation column kettle and the heater is intense. And a nitrogen atmosphere is employed for this improvement.

After completion of the reaction, unreacted alkyl (meth) acrylate, amino alcohol and the target alkylamino (meth) acrylate are distilled off and rectified to obtain a product. The bottoms are used in the reaction several times as a recovered catalyst, and are discarded due to a decrease in activity.

Further, since the reaction for synthesizing alkylamino (meth) acrylate by transesterification of alkyl (meth) acrylate with alkylaminoalcohol has high polymerizability, unreacted alkyl (meth) acrylate after the reaction is completed.
The bottoms from which the acrylate, amino alcohol and the target alkylamino (meth) acrylate are distilled off contain polymer components, and the viscosity of the recovered catalyst solution increases, making it difficult to handle liquid sending and the like. There was a problem.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and produces an alkylamino (meth) acrylate by subjecting (meth) acrylate and alkylamino alcohol to reactive distillation. In the method, a method for stably and efficiently distilling to produce a high-purity alkylamino (meth) acrylate is provided.

[0007]

Means for Solving the Problems Accordingly, the present inventors have:
In the method for producing the alkylamino (meth) acrylate, as a result of specifying the place where the polymerization occurs,
It was found that the alkyl acrylate was polymerized in the distillation column when the by-product alkyl alcohol was azeotropically separated with the alkyl (meth) acrylate using the distillation column, not in the reaction solution.

As a result of intensive studies on such problems, the present inventor has found that the use of the amine polymerization inhibitor (A) in the distillation column during the reactive distillation reduces the polymer content in the recovered catalyst solution. It has been found that the viscosity can be reduced and the viscosity can be reduced. However, since the by-product alkyl alcohol coexists with the alkyl (meth) acrylate, it is preferable to regenerate the alkyl (meth) acrylate in the presence of (meth) acrylic acid and an acid catalyst. For this reason, when the amine-based polymerization inhibitor (A) is mixed into the by-product alcohol, there is a problem in that it reacts with the acid catalyst to lower the catalytic activity. Therefore, the amine polymerization inhibitor (A) is introduced into the reflux line of the reactive distillation column, or is introduced into the cooler of the reactive distillation column, and azeotropic distillation of the by-product alkyl alcohol and alkyl (meth) acrylate is performed. Amine-based polymerization inhibitor (A)
Was found to be able to stably produce an alkylamino (meth) acrylate by removing the phenol from the bottoms, and the present invention was completed.

That is, the present invention provides the following general formula (1)

[0010]

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(Wherein, R ¹ is a hydrogen atom or a methyl group, and R ² is an alkyl group having 1 to 4 carbon atoms), and a (meth) acrylate represented by the following general formula (2):

[0012]

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(Wherein, R ³ is a hydrogen atom or a group having 1 to 1 carbon atoms)
8 is an alkyl group, R ⁴ is an alkyl group having 1 to 8 carbon atoms, and R ⁵ is an alkylene group having 1 to 4 carbon atoms)
With an alkylamino alcohol represented by the following formula (3):

[0014]

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In the method for producing an alkylamino (meth) acrylate represented by the formula (wherein each symbol is as defined above), the alkyl alcohol by-produced in the reaction is reacted with the (meth) acrylate in a reactive distillation column. , The separated alkyl alcohol is separated and recovered, and at least a part of the alkyl alcohol is refluxed to the reactive distillation column, and the amine-based polymerization inhibitor (A) coexists in the reflux liquid. The present invention relates to a method for producing an alkylamino (meth) acrylate, which is characterized in that it is subjected to a reactive distillation at a temperature of 1.

It is preferable from the viewpoint of production that the amine-based polymerization inhibitor (A) is introduced into the reflux line of the reactive distillation column or the upper part of the cooling device.

The amount of the amine polymerization inhibitor (A) to be added ranges from 10 ppm by weight to 2000 parts by weight based on the distillate at the top of the reactive distillation column.
It is preferable for the production to be in the range of ppm by weight.

The amine polymerization inhibitor (A) is introduced into the reflux line of the reactive distillation column, and at least one polymerization inhibitor (B) selected from the group consisting of hydroquinone, hydroquinone monomethyl ether, topanol A and catechol is added to It is preferable from the viewpoint of production that the liquid is charged into the upper part of the cooling device of the distillation column.

According to the above method, alkylamino (meth)
When the distillate obtained during the production of the acrylate is further continuously distilled using a distillation column to isolate the alkyl alcohol, the distillate obtained by distilling the distillate is treated with an alkyl alcohol and an alkyl (meth) acrylate. Is distilled off as an azeotropic composition, and the distillate is distilled in the presence of at least one polymerization inhibitor (B) selected from the group consisting of hydroquinone, hydroquinone monomethyl ether, topanol A and catechol. It is a more preferable method for production of amino (meth) acrylate.

The amount of the polymerization inhibitor (B) to be charged is preferably in the range of 1 ppm by weight to 1000 ppm by weight based on the amount distilled off at the top of the column.

It is preferable in terms of production to blow an oxygen-containing gas having a water content of 0.0001 to 0.05% by volume from the bottom of the distillation column.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The alkyl (meth) acrylate used in the present invention includes, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, n-butyl acrylate, n-butyl acrylate.
Butyl methcrete and the like can be mentioned. Particularly, use of methyl, ethyl and n-butyl (meth) acrylate is preferred.

The alkylamino alcohol used in the present invention includes, for example, dimethylaminoethanol, diethylaminoethanol, dipropylaminoethanol,
Dibutylaminoethanol, dipentylaminoethanol, dihexylaminoethanol, dioctylaminoethanol, methylethylaminoethanol, methylpropylaminoethanol, methylbutylaminoethanol, methylhexylaminoethanol, ethylpropylaminoethanol, ethylbutylaminoethanol, ethylpentylaminoethanol , Ethyloctylaminoethanol, propylbutylaminoethanol, dimethylaminopropanol, diethylaminopropanol,
Examples thereof include dipropylaminopropanol, dibutylaminopropanol, and butylpentylaminopropanol.

The amount of the alkyl (meth) acrylate used in the reaction is usually 1.2 to 10 mol, preferably 1.5 to 5 mol, per mol of the alkylamino alcohol used.
Mol% range.

The alkyl (meth) acrylate may be charged at the beginning of the reaction, or may be added partly.

The above-mentioned alkylamino alcohol may be charged all at once at the start of the reaction, but is preferably added to the reaction system. In this case, it is not necessary to charge at the start of the reaction, but a part of the charge may be charged at the start of the reaction. The molar concentration of the alkylamino alcohol when added to the reaction system is in the range of 25 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less in the reaction system.

The addition time of the alkylamino alcohol is as follows:
It is appropriately selected depending on the raw materials used and the amount, pressure, temperature, catalyst and the like. Usually, the addition may be started at the same time as the start of the reaction, and the addition is carried out so that the alkylamino alcohol concentration in the reaction system is kept at 25 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less.

The catalyst used in the reaction is not particularly limited as long as it is a known one, and examples thereof include titanium alcoholate, aluminum alcoholate, magnesium alcoholate, organotin compounds, zirconium compounds, zinc compounds, lead compounds, and thallium compounds. it can. In particular, organotin compounds such as dibutyltin oxide and dioctyltin oxide are preferred in terms of selectivity. The amount of the catalyst used is in the range of 0.01 to 10% by weight, more preferably 0.02 to 5% by weight, based on the total amount of the alkyl (meth) acrylate and the alkylamino alcohol.

The reaction temperature is 40 to 150 ° C., preferably 6
It can be performed in the range of 0 to 140 ° C. The reaction is usually carried out at normal pressure, but may be carried out under reduced or increased pressure as needed to adjust the reaction temperature.

The solvent need not be used, but can be used. When a solvent is used, the reaction can be carried out in the presence of an alkyl alcohol produced by the transesterification reaction and an inert solvent producing an azeotrope, for example, hexane, benzene, toluene, cyclohexane and the like.

In the reaction, usually, (1) a polymerization inhibitor is added to the liquid phase, and / or (2) an oxygen-containing gas is added to the liquid phase to prevent polymerization of the raw materials and products. Preferably.

Examples of the polymerization inhibitor for the reaction vessel used in (1) include phenothiazine, hydroquinone, hydroquinone monomethyl ether, di-t-butylcatechol, phenyl-β-naphthylamine, paraphenylenediamine, and the like. Alternatively, two or more are used. The amount of these used is 10 to 200 with respect to the total charge.
0 ppm by weight, preferably 100 to 1000 ppm by weight
Used in the range.

As the oxygen-containing gas used in (2), air, oxygen, and a diluent gas of an inert gas of air are used.
Examples of the inert gas include nitrogen, helium, and argon. There is no particular limitation on the oxygen concentration when diluted,
Preferably it is 0.01% by volume or more, more preferably 0.1% by volume. As the oxygen-containing gas to be used, air and gas obtained by diluting air with nitrogen are inexpensive and preferable.

The water concentration in the oxygen-containing gas is 0.00
01-0.25% by volume, preferably 0.001-0.1%
5% by volume, more preferably 0.01 to 0.05% by volume
Range. If the water content is less than 0.0001, it is more preferable, but it is expensive and industrial use is difficult. If the water content is large, the catalyst is deactivated and the generated alkylamino (meth) acrylate is hydrolyzed.

The blowing amount of the oxygen-containing gas is as follows:
Although it depends on the type of oxygen-containing gas used and the alkyl (meth) acrylate, the amount of gas that does not fall within the combustion range in the gas phase is preferable, and more preferably 0.01% by volume as oxygen relative to the overhead vapor in reactive distillation. 2% by volume
It is.

The oxygen-containing gas is injected into the liquid phase at the time of the reaction. Preferably, the purpose is to prevent the stirring of the liquid phase by bubbling and the obstruction of the outlet of the kettle due to the sedimentation of the easily sedimentable catalyst. Therefore, it is preferable to provide a blowing unit above the outlet valve for extracting the liquid from the kettle.

Further, in order to obtain the desired product in a high yield,
It is desirable to exclude alkyl alcohol by-produced in the transesterification reaction from the reaction system (so-called reactive distillation).
Specifically, it may be removed out of the system together with the unreacted alkyl (meth) acrylate, or may be removed out of the system by azeotropic distillation using the inert solvent.

In the reaction distillation, a polymerization inhibitor is usually added in the distillation column in the presence of oxygen to prevent polymerization of the alkyl (meth) acrylate in the distillation column. In order to allow oxygen to exist, it is conceivable to blow oxygen-containing gas into the liquid portion of the reaction vessel and blow oxygen-containing gas into the bottom of the reactive distillation column. As the oxygen-containing gas, the above-mentioned oxygen-containing gas is used. As the blowing amount of the oxygen-containing gas,
Although it depends on the type of oxygen-containing gas used and the alkyl (meth) acrylate, the amount of gas that does not fall within the combustion range in the gas phase is preferable, and more preferably 0.01% by volume as oxygen relative to the overhead vapor in reactive distillation. 2% by volume
It is.

As the polymerization inhibitor used in combination with the oxygen-containing gas for the purpose of preventing polymerization in the reactive distillation column, an amine-based polymerization inhibitor (A) is preferable, and the amine-based polymerization inhibitor (A) is contained in the reflux liquid of the reactive distillation column. It is characterized in that distillation is carried out in the coexistence of A).

As the amine polymerization inhibitor (A), diphenylamine, N, N'-diphenyl-p-phenylenediamine, α-naphthylamine, phenyl-β-naphthylamine, N, N'-di-sec-butyl-p -Phenylenediamine, phenothiazine, paraphenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-
Dihydroquinoline, N-phenyl-N'-isopropyl-p-phenylenediamine 4,4'-dioctyl-diphenylamine and the like;
More than seeds are used.

The amount of these used is 10 to 2
000 weight ppm, preferably 100-1000 weight p
pm range.

As a method for coexisting the amine-based polymerization inhibitor (A) in the reflux liquid of the reactive distillation column, the amine-based polymerization inhibitor is dissolved in the distillate of the reactive distillation column or an alkyl (meth) acrylate or the like. A method of supplying to the reflux line or a method of supplying to the upper part of the condenser of the reactive distillation column is employed. When supplying an amine polymerization inhibitor to the reflux line,
Hydroquinone, hydroquinone monomethyl ether, topanol A to suppress polymerization in the distillation tower cooler
And at least one selected from the group consisting of catechol
The kind of polymerization inhibitor (B) is charged into the upper part of the cooling device of the distillation column.

The amount of the polymerization inhibitor (B) charged into the upper part of the cooling device of the distillation column is preferably in the range of 1 ppm by weight to 1000 ppm by weight based on the distillation amount at the top of the column.

Since the alkyl alcohol by-produced in the reaction contains an alkyl acrylate, it is preferable to react it with acrylic acid and use it again as a raw material as an alkyl acrylate.

In the case of esterification with acrylic acid, if there is a basic component in the by-product alcohol solution, a neutralization reaction with the acid catalyst at the time of esterification occurs, causing a decrease in the activity of the catalyst. For this reason, it is preferable to perform distillation and / or adsorption treatment with an ion-exchange resin to remove the basic component before esterification.

In the distillation, an azeotrope of alkyl alcohol and alkyl (meth) acrylate by-product is distilled off from the top of the column,
An alkyl (meth) acrylate is obtained as a bottom liquid.

In the distillation, a polymerization inhibitor is added in the distillation column in the presence of oxygen to prevent polymerization of the alkyl acrylate. In order to make oxygen exist, the oxygen-containing gas may be blown into the distillation column, and the oxygen-containing gas is used as the oxygen-containing gas.

The amount of the oxygen-containing gas blown varies depending on the type of the oxygen-containing gas used and the alkyl (meth) acrylate, but is preferably an amount of gas that does not fall within the combustion range in the gas phase, more preferably a column in the reactive distillation. It is 0.01% to 2% by volume as oxygen with respect to the top steam.

As the polymerization inhibitor used in combination with the oxygen-containing gas for the purpose of preventing polymerization in the distillation column, a polymerization inhibitor having no basicity is preferable, and one or more of the polymerization inhibitors (B) are used. used.

The amount of the polymerization inhibitor (B) used is 1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, based on the amount of distillate.
Used in the range of ppm by weight, diluted with the distillation column distillate,
It is preferable to put in from the top of the cooler.

As the adsorption by the ion exchange resin, a method of circulating a treatment tank filled with a weakly acidic ion exchange resin is preferable.

(Distillation step) After completion of the reaction, unreacted alkyl (meth) acrylate and alkylamino alcohol are first distilled off under reduced pressure, and then the crude alkylamino (meth) acrylate, which is a target product, is removed. The catalyst is distilled off to obtain a bottom product. There are no particular restrictions on the method for recovering the catalyst, but the batch distillation (evaporation) method and distillation (evaporation)
A continuous distillation method using two or more devices is employed.

To prevent polymerization at the time of recovery of the catalyst, it is possible to employ, for example, blowing an oxygen-containing gas into a liquid phase portion and feeding a polymerization inhibitor into a distillation tower cooler.

As the oxygen-containing gas, the oxygen-containing gas at the time of the reaction is employed for the purpose of preventing the deactivation of the catalyst and the hydrolysis of the formed alkylamino (meth) acrylate. The amount of the oxygen-containing gas blown into the liquid phase is preferably such that the gas does not fall into the combustion range in the gas phase, and more preferably 0.1% as oxygen relative to the vapor at the top in the reactive distillation.
It is from 01% by volume to 2% by volume.

As the polymerization inhibitor used in combination with the oxygen-containing gas, the above-mentioned amine polymerization inhibitors are preferable.

These are used in an amount of 0.001 to 2% by weight, preferably 0.01 to 1% by weight, based on the weight of the distillation at the top of the column.
Used in the range.

The crude target alkylamino (meth) acrylate contains unreacted raw materials and high-boiling impurities, so that it is purified by distillation. As a distillation method, batch distillation and continuous distillation in which two or more distillation apparatuses are used to perform a light boiling distillation step and a purification step are employed.

To prevent polymerization at the time of distillation purification, blowing of an oxygen-containing gas into a liquid phase portion, introduction of a polymerization inhibitor into a distillation tower cooler, and the like are employed.

Examples of the polymerization inhibitor used in combination with the oxygen-containing gas include phenothiazine, hydroquinone, hydroquinone monomethyl ether, di-t-butylcatechol, phenyl-β-naphthylamine, and paraphenylenediamine. More than seeds are used.

[0060] These amounts are used in an amount of 0.1 to the total charged weight.
It is used in the range of 005 to 2% by weight, preferably 0.01 to 1% by weight.

The bottom of the rectification step tower still contains some alkylamino (meth) acrylate.
Therefore, it is desirable to further recover the alkylamino (meth) acrylate in a thin film distillation column or the like.

To prevent polymerization of the thin-film distillation column, it is possible to employ a method in which an oxygen-containing gas is blown into the gas phase and a polymerization inhibitor is introduced into the distillation column cooler.

Examples of the polymerization inhibitor used in combination with the oxygen-containing gas include phenothiazine, hydroquinone, hydroquinone monomethyl ether, di-tert-butylcatechol, phenyl-β-naphthylamine, and paraphenylenediamine. More than seeds are used.

These amounts are used in an amount of 0.1 to the total charged weight.
It is used in the range of 005 to 2% by weight, preferably 0.01 to 1% by weight.

The removal of the catalyst and the steps of purifying and recovering the alkylamino (meth) acrylate are desirably performed at 130 ° C. or lower from the viewpoint of suppressing the thermal polymerization reaction.

An example of the reaction method of the present invention will be described with reference to FIG.

In the reaction vessel 1, alkyl (meth) acrylate and alkylamino alcohol are subjected to transesterification to produce alkylamino (meth) acrylate,
Using the reactive distillation column 3, the alkyl alcohol by-produced is distilled off with the alkyl (meth) acrylate. The polymerization inhibitor (B) is charged from the charging portion of B, and the distillate is cooled by the cooling device 5. Next, a certain amount of the cooled distillate is returned to the reactive distillation column 3 through the piping 6 using the flow control pump 7 and the reactive distillation column reflux line 8. At this time, the polymerization inhibitor (A) is introduced from the column A inlet. The remaining distillate is collected in a receiver 10 through a pipe 9.

A preferred example of the reaction method of the present invention will be described with reference to FIG.

The alkyl (meth) acrylate and the alkylamino alcohol are subjected to a transesterification reaction in the reaction vessel 1 to produce an alkylamino (meth) acrylate.
Using the reactive distillation column 3, the alkyl alcohol by-produced is distilled off with the alkyl (meth) acrylate. The polymerization inhibitor (A) is charged from the charging portion of A, and the distillate is cooled by the cooling device 5. Next, a certain amount of the cooled distillate is returned to the reactive distillation column 3 through the distillation column reflux line 8 using the flow control pump 7 through the pipe 6. The remaining distillate is collected in a receiver 10 through a pipe 9.

Further, the mixture is sent to the distillation column 14 through the pump of the distillation column 12, and alkyl (meth) acrylate is supplied from the bottom of the column, and alkyl alcohol and alkyl (meth) are supplied from the top of the column.
Distill an azeotrope with acrylate. The polymerization inhibitor (B) is charged from the charging portion of C, and the distillate is cooled by the cooling device 16. Next, a certain amount of the cooled distillate is returned to the distillation column 14 through the distillation column reflux line 19 by using the flow control pump 18 through the pipe 17. The remaining distillate is collected in a receiver 21 through a pipe 20.

[0071]

The present invention will be described below in more detail with reference to examples. GPC analysis of the recovered catalyst solution was performed by the following method.

(GPC analysis of recovered catalyst solution)
Using -802 (manufactured by Showa Denko), the sample was analyzed with a THF solvent. The detector used was an RI detector. Also,
The polymer component having a molecular weight of 1,000 or more was used.

The yield was calculated by the following calculation.

Yield (%) = (alkylamino (meth) acrylate yield (mol)) ÷ ((amino alcohol (mol) charged in reaction) − (amino alcohol (mol) recovered by purification)) × 100 Example 1 The following operation was performed using air having a moisture content of 0.037% (hereinafter referred to as air (I)) as a blown gas.

Step 1. (Reactive distillation step) 159.9 parts (1.8 mol) of dimethylaminoethanol and 1549. of methyl acrylate were placed in a 3 L flask having an inner volume equipped with a stirrer, a thermometer, an air blowing tube, and a fractionating tower (the number of theoretical plates is 6). 5 parts (18.0 mol), 16.0 parts of dibutyltin oxide as a catalyst, and 8.7 parts of phenothiazine as a polymerization inhibitor were introduced, and AIR (I) was blown in at 0.5 vol% with respect to the overhead vapor. The mixture was heated with stirring at normal pressure. After the commencement of the distillation, 641.7 parts (7.2 mol) of dimethylaminoethanol was added so that the concentration of dimethylaminoethanol in the reaction system did not exceed 10 mol%, and 0.1 mol of phenothiazine was added to the fractionation column. A 25% by weight methyl acrylate solution was introduced from the reflux line of the fractionation tower so that phenothiazine was 500 ppm by weight based on the amount of the distillate, and 0.25% by weight of hydroquinone monomethyl ether methyl acrylate from the top of the fractionation tower cooler. The solution was added so as to be 250 ppm by weight based on the amount of distillate. The addition time of dimethylaminoethanol was 4 hours. The produced methanol was distilled off as a methanol / methyl acrylate azeotrope at a reflux ratio of 0.5 to 5.0 while maintaining the top temperature of the fractionation tower at 62 to 70 ° C. The reaction was completed in 8 hours, and the reaction mixture was analyzed. The conversion of dimethylaminoethanol was 95% and the selectivity was 98%.

Step 2. (Azeotropic distillation step) The distillate obtained in step 1 was distilled under a normal pressure using a distillation apparatus (the number of theoretical plates is 6). Hydroquinone monomethyl ether 0.25% by weight methyl acrylate solution was charged from the upper part of the condenser of the distillation apparatus so that the hydroquinone monomethyl ether was 50 ppm by weight with respect to the distillate amount, and AIR (I) was supplied from the bottom of the distillation apparatus. 0.5 for rising steam
The azeotropic distillate of methanol / methyl acrylate was taken out at a reflux ratio of 1.5 and a top temperature of 62 ° C. at a reflux ratio of 1.5% by volume, and methyl acrylate was taken out from the bottom of the column.

Step 3. (Catalyst recovery step) The bottom liquid obtained in step 1 is placed in a 3 L flask having an inner volume equipped with a stirrer, a thermometer, an air blowing tube, and an empty tower. Pressure ~ 100m
The liquid containing mainly methyl acrylate was distilled off at mHg and a temperature in the kettle of 75 to 90 ° C, and the pressure was further increased to 100 to 20.
Distillation was performed at a pressure of 80 mmHg and an internal temperature of 80 to 110 ° C. to obtain a liquid containing 73% of dimethylaminoethyl acrylate. A liquid containing dibutyltin oxide and phenothiazine was obtained from the bottom of the can. This solution was used as a catalyst solution in the next reaction. The yield (mol%) was 93.6%. GPC analysis of the recovered catalyst solution showed no polymer component.

Example 2 In Example 1, the water content was 0.01% and the oxygen concentration was 7 VO.
L% / 93% nitrogen gas and N, N'-diphenylamine as a stabilizer in the reactive distillation column were used in the part of the reactive distillation column cooler, except that no stabilizer was supplied to the reflux line. Operated. The yield (mol%) was 93.5. According to GPC analysis of the recovered catalyst solution, there was no polymer component.

Comparative Example 1 In Example 1, the water content was 0.01% and the oxygen concentration was 7 VO.
The same operation was performed except that a gas of L% / 93% of nitrogen and hydroquinone monomethyl ether were used as a stabilizer for the reactive distillation column in the portion of the reactive distillation column cooler, and no particular stabilizer was supplied to the reflux line. . The yield (mol%) is 8
3.7%. According to GPC analysis of the recovered catalyst solution, the polymer component was 8.3 area%.

[0080]

According to the method of the present invention, not only the polymerization of alkylamino (meth) acrylate and various by-products during distillation but also the formation of salts due to hydrolysis can be prevented. A high purity alkylamino (meth) acrylate can be produced, and the residual liquid after distillation of the liquid subjected to distillation is prevented from becoming highly viscous, and the residual liquid can be easily sent and transferred. , Alkylamino (meth) acrylate can be stably distilled.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of a manufacturing method according to the present invention.

FIG. 2 is a flowchart illustrating an example of a manufacturing method according to the present invention.

[Explanation of symbols]

 1. Reaction kettle 2. Connection piping 3. Reactive distillation column 4. Distillation line 5. Cooling device 6. Connection piping 7. 7. Flow control pump 8. Reactive distillation column reflux line Connection piping 10. Receiver 11. Connection piping 12. Flow control pump 13. Connection piping 14. Distillation tower 15. Connection piping 16. Cooling device 17. Connection piping 18. Flow control pump 19. Distillation tower reflux line 20. Connection piping 21. Receiver 22. Connection piping 23. Connection piping 24. Heat exchanger 25. Connection piping A. Polymerization inhibitor (A) charging section B. C. Injection section for polymerization inhibitor (B) Polymerization inhibitor (B) charging section

Claims (7)

[Claims] [Claim 1] The following general formula (1) (Wherein, R ¹ is a hydrogen atom or a methyl group, and R ² is an alkyl group having 1 to 4 carbon atoms), and (meth) acrylate represented by the following general formula (2): (Wherein, R ³ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁴ is an alkyl group having 1 to 8 carbon atoms, R ⁵
Is an alkylene group having 1 to 4 carbon atoms) with an alkylamino alcohol represented by the following general formula (3): (Wherein each symbol is the same as described above), a method for producing alkylamino (meth) acrylate represented by the formula: , And at least a portion of the alkyl alcohol is refluxed to the reactive distillation column, and reactive distillation is carried out in the presence of the amine polymerization inhibitor (A) in the reflux liquid. A method for producing an alkylamino (meth) acrylate. 2. The production method according to claim 1, wherein the amine polymerization inhibitor (A) is introduced into a reflux line of a reactive distillation column or an upper part of a cooling device. 3. The amount of the amine-based polymerization inhibitor (A) charged is:
10 to 200 ppm by weight based on the distillate at the top of the reactive distillation column
3. The production method according to claim 1, wherein the amount is in a range of 0 ppm by weight. 4. An amine polymerization inhibitor (A) is charged into a reflux line of a reactive distillation column, and at least one polymerization inhibitor (B) selected from the group consisting of hydroquinone, hydroquinone monomethyl ether, topanol A and catechol. Is charged into the upper part of the cooling device of the distillation column.
4. The production method according to 2 or 3. 5. An alkyl alcohol obtained by continuously distilling a distillate obtained in producing an alkylamino (meth) acrylate by the method according to claim 1 using a distillation column. When isolating the distillate, the above-mentioned distillate is distilled off with an azeotropic composition of alkyl alcohol and alkyl (meth) acrylate, and the distillate comprises hydroquinone, hydroquinone monomethyl ether, topanol A and catechol. A method for producing an alkylamino (meth) acrylate, wherein the distillation is carried out in the presence of at least one polymerization inhibitor (B) selected from the group. 6. The distillation method according to claim 4, wherein the amount of the polymerization inhibitor (B) is in the range of 1 to 1000 ppm by weight based on the amount of distillation at the top of the column. 7. A water content of 0.0001 from the bottom of the distillation column.
7. The method according to claim 1, wherein an oxygen-containing gas of 0.05% by volume is blown into the gas.