Production method of amino group-containing (METH)acrylic acid ester

Abstract

To provide a production method capable of obtaining an amino group-containing (meth)acrylic acid ester at a high yield with less impurities by a side reaction without using a large amount of transesterification catalyst.SOLUTION: A production method of a (meth)acrylic acid ester includes the following steps (1) to (2): (1) a step (addition and mixing step) of obtaining a reaction mixture by heating a mixture comprising an N,N-dialkyl alkanolamine having 4 to 6 carbon atoms, a metal alkoxide and an organotin compound and not containing a (meth)acrylic acid alkyl ester and by adding the (meth)acrylic acid alkyl ester at a temperature of the mixture being equal to or lower than the boiling point of an alcohol to be distilled off; and (2) a step (transesterification step) of performing transesterification by further applying heat after the addition and mixing step (1) and by distilling off the alcohol at a temperature of the mixture exceeding the boiling point of the alcohol to be distilled off.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing an amino group-containing (meth)acrylic acid ester. [Background technology]

[0002] The (meth)acrylic acid ester can be formed by transesterifying (meth)acrylic acid methyl ester or the like with an alcohol corresponding to the (meth)acrylic acid ester in the presence of a transesterification catalyst and removing the by-product low-boiling alcohol (methanol, etc.).

[0003] As a transesterification method with high reaction efficiency and minimal impurities due to side reactions, a transesterification method has been proposed in which the step of adding a transesterification catalyst is carried out multiple times each time the rate of production of the by-product alcohol slows down (Patent Document 1). However, there is a problem in that a large amount of transesterification catalyst is required to achieve a sufficient yield of (meth)acrylic acid ester. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2006-206590 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above-mentioned problems of the conventional art, and an object of the present invention is to provide a method for producing a (meth)acrylic acid ester, which can produce an amino group-containing (meth)acrylic acid ester in high yield with few impurities due to side reactions, without using a large amount of a transesterification catalyst. [Means for solving the problem]

[0006] As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention is a method for producing a (meth)acrylic acid ester, which comprises obtaining an amino group-containing (meth)acrylic acid ester by distilling off an alcohol from a reaction mixture containing an N,N-dialkylalkanolamine having 4 to 6 carbon atoms and an alkyl (meth)acrylate having 1 to 4 carbon atoms in the alkyl group, and performing a transesterification reaction. The method for producing a (meth)acrylic acid ester has the following steps (1) to (2). (1) A step of heating a mixture containing an N,N-dialkylalkanolamine having 4 to 6 carbon atoms, a metal alkoxide, and an organotin compound and not containing an alkyl (meth)acrylate, and adding an alkyl (meth)acrylate at a temperature at which the temperature of the mixture is equal to or lower than the boiling point of the alcohol to be distilled off to obtain a reaction mixture (addition mixing step). (2) A step of further heating after the addition mixing step of (1) and distilling off the alcohol at a temperature at which the temperature of the reaction mixture exceeds the boiling point of the alcohol to be distilled off to perform a transesterification reaction (transesterification step). [Effect of the Invention]

[0007] The method for producing a (meth)acrylic acid ester of the present invention has an effect that an amino group-containing (meth)acrylic acid ester can be obtained in a high yield with few impurities due to side reactions without using a large amount of a transesterification catalyst. [Embodiments for Carrying Out the Invention]

[0008] The present invention is a method for producing a (meth)acrylic acid ester, which comprises obtaining an amino group-containing (meth)acrylic acid ester by distilling off an alcohol from a reaction mixture containing an N,N-dialkylalkanolamine having 4 to 6 carbon atoms and an alkyl (meth)acrylate having 1 to 4 carbon atoms in the alkyl group, and performing a transesterification reaction.

[0009] Examples of N,N-dialkylalkanolamines having 4 to 6 carbon atoms that can be used in the present invention include 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, and 4-(dimethylamino)butanol. Of these, 2-(dimethylamino)ethanol and 4-(dimethylamino)butanol are preferred in terms of product yield.

[0010] Examples of the (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 4 carbon atoms that can be used in the present invention include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. Of these, methyl (meth)acrylate and ethyl (meth)acrylate are preferred from the viewpoint of the boiling point of the alcohol produced, and methyl methacrylate is more preferred.

[0011] The alcohol distilled off from the reaction mixture containing the N,N-dialkylalkanolamine having 4 to 6 carbon atoms and the (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group is an alcohol derived from the (meth)acrylic acid alkyl ester used, and is methanol in the case of methyl (meth)acrylate, ethanol in the case of ethyl (meth)acrylate, propyl alcohol in the case of propyl (meth)acrylate, and butanol in the case of butyl (meth)acrylate. By distilling off the alcohol, a transesterification reaction is carried out between an N,N-dialkylalkanolamine having 4 to 6 carbon atoms and a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms.

[0012] The production method of the present invention is a production method of a (meth)acrylic acid ester comprising the following steps (1) and (2). (1) A step of heating a mixture containing an N,N-dialkylalkanolamine having 4 to 6 carbon atoms, a metal alkoxide, and an organotin compound, but not containing an alkyl (meth)acrylate, and adding an alkyl (meth)acrylate at a temperature equal to or lower than the boiling point of the alcohol being distilled off to obtain a reaction mixture (addition and mixing step). (2) A step of further heating the reaction mixture after the adding and mixing step (1) and distilling off the alcohol at a temperature exceeding the boiling point of the alcohol to be distilled off to carry out transesterification (transesterification step).

[0013] Examples of the metal alkoxide contained in the mixture prepared in the adding and mixing step include residues obtained by removing hydrogen atoms from hydroxyl groups of monoalcohols having 1 to 4 carbon atoms (methanol, ethanol, n-propanol, sec-propanol, n-butanol, iso-butanol, and tert-butanol), and examples of the metal atom that constitutes the metal alkoxide include alkali metal atoms. Preferred metal alkoxides include sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium methoxide, and lithium ethoxide, and from the viewpoints of basicity and reaction selectivity, sodium methoxide and potassium methoxide are more preferred, and sodium methoxide is particularly preferred.

[0014] Examples of the organotin compound contained in the mixture prepared in the addition and mixing step include trialkyltin compounds, dialkyltin compounds, and diaryltin compounds, with dialkyltin compounds being preferred, dibutyltin oxide, dibutyltin diacetate, and dibutyltin dilaurate being more preferred, and dibutyltin oxide being particularly preferred from the viewpoint of reactivity.

[0015] From the viewpoint of suppressing side reactions, the amount of substance of the metal alkoxide contained in the mixture prepared in the addition mixing step is preferably 0.002 mol to 0.0025 mol, more preferably 0.002 mol, per 1 mol of the N,N-dialkylalkanolamine.

[0016] From the viewpoint of suppressing the reaction time, the amount of substance of the organotin compound contained in the mixture prepared in the addition mixing step is preferably 0.002 mol to 0.0025 mol, more preferably 0.002 mol, per 1 mol of the N,N-dialkylalkanolamine.

[0017] From the viewpoint of suppressing side reactions, the molar ratio of the metal alkoxide to the organotin compound (number of moles of metal alkoxide: number of moles of organotin compound) contained in the mixture prepared in the addition mixing step is preferably 0.8:1 to 1.2:1, and most preferably 1:1. Examples of side reactions that can be suppressed by adjusting the amount of substance of the metal alkoxide and the organotin compound include the reaction between the oxygen atom of the N,N-dialkylalkanolamine and the unsaturated bond of the alkyl (meth)acrylate. Examples of impurities generated by side reactions include (methyl)propanoic acid alkyl ester derivatives formed by bonding the residue obtained by removing a hydrogen atom from the hydroxyl group of the N,N-dialkylalkanolamine to the unsaturated bond of the alkyl (meth)acrylate as a raw material and the produced amino group-containing (meth)acrylate ester.

[0018] The mixture prepared in the addition mixing step can be obtained by mixing a dialkylalkanolamine having 4 to 6 carbon atoms, a metal alkoxide, and an organotin compound in a mixing container equipped with a stirrer. It is preferable to use a reaction vessel equipped with a heating device and a condenser as the mixing container, as it enables continuous performance of the preparation of the reaction mixture and subsequent steps (such as the transesterification step).

[0019] The mixture prepared in the adding and mixing step may contain components other than the dialkylalkanolamine having 4 to 6 carbon atoms, the metal alkoxide, and the organotin compound, as long as it does not contain the (meth)acrylic acid alkyl ester. If the (meth)acrylic acid alkyl ester is contained, side reactions are likely to occur, resulting in a reduced yield. Components that may be contained in the mixture include a polymerization inhibitor and the above-mentioned alcohols in which the alkyl group has 1 to 4 carbon atoms. As the polymerization inhibitor, known polymerization inhibitors can be used, and preferred examples include phenothiazine, hydroquinone, mequinol, and catechol.

[0020] The production method of the present invention includes a step (addition and mixing step) of heating the mixture prepared in the addition and mixing step, and adding an alkyl (meth)acrylate ester at a temperature of the mixture not higher than the boiling point of the alcohol being distilled off to obtain a reaction mixture.

[0021] The mixture can be heated using a reaction vessel equipped with a heater and a condenser, and the reaction vessel may be a batch or continuous reaction vessel.

[0022] The mixture is preferably heated under atmospheric pressure. The rate at which the temperature of the mixture is increased is not limited as long as the temperature can be increased to a temperature not exceeding the boiling point of the alcohol being distilled off.

[0023] In the adding and mixing step, the (meth)acrylic acid alkyl ester is added at a temperature of the mixture not higher than the boiling point of the alcohol being distilled off. The amount of the (meth)acrylic acid alkyl ester to be added is preferably 1.0 to 2.0 moles per mole of N,N-dialkylalkanolamine contained in the mixture.

[0024] The boiling point of the alcohol to be distilled off, which is a guideline for adding the alkyl (meth)acrylate to the mixture, is the boiling point of alcohol at 1 atmosphere, and the boiling point of methanol is 64°C, the boiling point of ethanol is 78°C, and the boiling point of butanol is 98°C. When an alkyl (meth)acrylate is added at a temperature exceeding the boiling point of the alcohol to be distilled off, side reactions are likely to occur and the yield deteriorates.

[0025] The addition of the alkyl (meth)acrylate may be carried out at a temperature below the boiling point of the alcohol to be distilled off. From the viewpoint of suppressing side reactions, the temperature of the mixture is preferably from 10 °C lower than the boiling point of the alcohol to be distilled off to a temperature below the boiling point of the alcohol.

[0026] The addition of the alkyl (meth)acrylate is preferably carried out while stirring with a stirrer attached to the addition reactor. The addition and mixing of the alkyl (meth)acrylate are preferably carried out under atmospheric pressure. If the temperature in the reaction vessel is below the boiling point of the alkyl alcohol during the addition and mixing of the alkyl (meth)acrylate, the heating during the addition of the alkyl (meth)acrylate may be stopped or continued, and the temperature in the reaction vessel during the addition of the alkyl (meth)acrylate may be constant, rising, or falling.

[0027] In the addition and mixing step, it is preferable to have a temperature maintaining step of maintaining the temperature in the reaction vessel constant before adding the alkyl (meth)acrylate. By maintaining the temperature in the reaction vessel constant when adding the alkyl (meth)acrylate, side reactions are less likely to occur and the yield is improved. As the temperature to be kept constant in the temperature maintaining step, when the alcohol to be distilled off is methanol, it is preferably 64 °C, and when it is n-butanol, it is preferably 98 °C. The time for keeping the temperature constant can be changed depending on the scale of the reactor, but 60 minutes is preferable, and 30 minutes is particularly preferable.

[0028] The production method of the present invention has a step (transesterification step) of further heating after the above addition and mixing step to distill off the alcohol and perform transesterification.

[0029] The heating after the above-mentioned addition and mixing step is carried out by heating the reaction vessel with an attached heating device or the like. By performing the heating, the alcohol generated in the transesterification reaction vaporizes, and the alcohol vaporized by an attached condenser or the like is cooled and liquefied, so that the alcohol is distilled off outside the reaction system, the transesterification reaction proceeds, and an amino group-containing (meth)acrylate is generated.

[0030] There is no limitation on the heating device in the transesterification reaction step. The upper limit of the temperature in the reaction vessel in the transesterification reaction step is preferably 150 °C. The pressure in the reaction vessel in the transesterification reaction may be in any state of reduced pressure, normal pressure, and increased pressure, but the transesterification reaction step is preferably carried out under atmospheric pressure.

[0031] The production method of the present invention may have a step of purifying the generated amino group-containing (meth)acrylate. The purification of the amino group-containing (meth)acrylate can be carried out by known methods such as solvent extraction, distillation, and rectification.

[0032] The step of purifying the amino group-containing (meth)acrylate may be carried out by adding a polymerization inhibitor. As the polymerization inhibitor, phenothiazine, hydroquinone, mequinol, catechol, etc. can be used.

[0033] The production method of the (meth)acrylate of the present invention can produce an amino group-containing (meth)acrylate in a high yield while suppressing side reactions. Therefore, the amino group-containing (meth)acrylate obtained by the production method of the present invention can be preferably used as a synthetic raw material for resin for paints, resin for adhesives, ion exchange resins, lubricating oil additives, compounding agents for rubbers, paper processing agents, and fiber treating agents.

Example

[0034] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[0035] <Example 1> Production of Amino Group-Containing (Meth)acrylate (addition mixing process) 153 g of 2-(dimethylamino)ethanol (Tokyo Chemical Industry Co., Ltd.), 1.3 g of phenothiazine (Seiko Chemical Co., Ltd.) as a polymerization inhibitor, 0.8 g of dibutyltin oxide (Nitto Kasei Co., Ltd.) as a catalyst, and 0.8 g of 24 wt% sodium methoxide (methanol solution) (Nippon Soda Co., Ltd.) were added to a four-necked flask equipped with a stirrer, thermometer, air inlet tube, and a distillation apparatus using a Vigreux tube, and the mixture was stirred to prepare a mixture. Heating was then started while stirring, and once the temperature in the flask reached 64°C, the heating was adjusted to maintain 64°C for 1 hour. Then, 247 g of methyl methacrylate was added at 64° C. with stirring to obtain a reaction mixture. (Interesterification process) The reaction mixture was then further heated, and the vaporized components (azeotropic mixture of methanol and methyl methacrylate) were distilled off while cooling with a Vigreux tube to carry out the transesterification process. Vaporization began when the reaction mixture reached 94°C. The maximum temperature reached at the top of the Vigreux tube during distillation was 75°C, and the vaporized components were distilled off until the temperature dropped to 60°C after reaching the maximum. Heating was continued as the vaporized components were distilled off, raising the temperature inside the reaction vessel. When the temperature inside the reaction vessel reached 120°C, heating was stopped, terminating the transesterification reaction and yielding a transesterification reaction mixture containing an amino group-containing (meth)acrylic acid ester. It took 9 hours from the start of distillation to reach 120°C. The reaction mixture after the transesterification reaction was subjected to gas chromatography (GC) analysis under the measurement conditions described below, and the ratio (product yield) of the amino group-containing (meth)acrylic acid ester [2-(dimethylamino)ethyl methacrylate] to the remaining N,N-dialkylalkanolamine [2-(dimethylamino)ethanol] contained in the reaction mixture, and the ratio (by-product ratio) of the methylpropanoic acid alkyl ester derivatives [methyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate and 2-(dimethylamino)ethyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate] produced by side reactions were calculated by the methods described below and are shown in Table 3.

[0036] <Measurement Conditions of GC> GC apparatus: Agilent 7890A GC Column: DB-WAX (30 m × 0.25 mm × 0.25 μm) Carrier gas: Helium Injector temperature: 250 °C Detector temperature: 250 °C Temperature program: The initial temperature of 40 °C is held for 5 minutes, then the temperature is increased at a rate of 10 °C / min to 250 °C and held for 10 minutes. Sample injection volume: 1 μL Analysis time: 30 minutes

[0037] <Calculation Procedure for Product Yield (%) and By-Product Ratio (%)> (1) Relative Sensitivity of Each Component in GC Analysis Approximately 1 g of methyl methacrylate, approximately 1 g of 2-(dimethylamino)ethanol, approximately 1 g of methanol which is the alcohol to be distilled off, approximately 1 g of 2-(dimethylamino)ethyl methacrylate which is an amino group-containing (meth)acrylate ester, and approximately 1 g of methyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate and approximately 1 g of 2-(dimethylamino)ethyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate which are by-products were weighed to the fourth decimal place, and all were dissolved in 100 g of acetone to prepare a standard sample with known component amounts. GC analysis of the standard sample was performed under the above conditions, and the component amounts of each component and the peak areas of each component in the standard sample were substituted into the following calculation formula to determine the relative sensitivity of each component with respect to 2-(dimethylamino)ethyl methacrylate. Note that five standard samples with known component amounts containing the same content were prepared, and GC measurement and calculation were performed for each of them. The decimal part of the arithmetic mean value was rounded down to obtain the relative sensitivity of each component. Calculation formula (1): Relative sensitivity of methyl methacrylate (K1) = {weight value of methyl methacrylate / weight value of 2-(dimethylamino)ethyl methacrylate} ÷ {peak area of methyl methacrylate / peak area of 2-(dimethylamino)ethyl methacrylate} Calculation formula (2): Relative sensitivity (K2) of 2-(dimethylamino)ethanol = {Weight value of 2-(dimethylamino)ethanol / Weight value of 2-(dimethylamino)ethyl methacrylate} ÷ {Peak area of 2-(dimethylamino)ethanol / Peak area of 2-(dimethylamino)ethyl methacrylate} Calculation formula (3): Relative sensitivity (K3) of methanol = {Weight value of methanol / Weight value of 2-(dimethylamino)ethyl methacrylate} ÷ {Peak area of methanol / Peak area of 2-(dimethylamino)ethyl methacrylate} Calculation formula (4): Relative sensitivity (K4) of by-product 1 = {Weight value of by-product 1 / Weight value of 2-(dimethylamino)ethyl methacrylate} ÷ {Peak area of by-product 1 / Peak area of 2-(dimethylamino)ethyl methacrylate} Note that by-product 1 means methyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate. Calculation formula (5): Relative sensitivity (K5) of by-product 2 = {Weight value of by-product 2 / Weight value of 2-(dimethylamino)ethyl methacrylate} ÷ {Peak area of by-product 2 / Peak area of 2-(dimethylamino)ethyl methacrylate} Note that by-product 2 means 2-(dimethylamino)ethyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate.

[0038] (2) Calculation of product yield (%) For the reaction mixture obtained in Example 1, GC analysis was performed. From the obtained chromatogram, the peak areas of 2-(dimethylamino)ethyl methacrylate and 2-(dimethylamino)ethanol were read, and the read peak areas and the relative intensity (K2) of 2-(dimethylamino)ethanol were substituted into the following calculation formula (6) to obtain the product yield. Calculation formula (6): Product yield (%) = {(Peak area of 2-(dimethylamino)ethyl methacrylate) ÷ 157} ÷ [{(Peak area of 2-(dimethylamino)ethyl methacrylate) ÷ 157} + K2 × {(Peak area of 2-(dimethylamino)ethanol) ÷ 89)}] × 100 In the calculation formula (6), 157 is the molecular weight of 2-(dimethylamino)ethyl methacrylate, and 89 is the molecular weight of 2-(dimethylamino)ethanol.

[0039] (3) Calculation of the by-product ratio (%) From the chromatogram obtained by GC analysis of the reaction mixture obtained in Example 1, the peak areas of methyl methacrylate, 2-(dimethylamino)ethanol, methanol, 2-(dimethylamino)ethyl methacrylate, methyl 3-[2-(dimethylamino)ethoxy]-2-methylpropanoate, and 2-(dimethylamino)ethyl 3-[2-(dimethylamino)ethoxy]-2-methylpropanoate were read, and the read peak areas and the relative intensities of each component were substituted into the following calculation formula (7) to calculate the by-product ratio (%). Calculation formula (7): By-product ratio (%) = (F1 + F2) / (F1 + F2 + F3 + F4 + F5 + S0) In the calculation formula (7), F1 is the value obtained by multiplying the peak area of methyl 3-[2-(dimethylamino)ethoxy]-2-methylpropanoate by the relative intensity of methyl 3-[2-(dimethylamino)ethoxy]-2-methylpropanoate. F2 is the value obtained by multiplying the peak area of 2-(dimethylamino)ethyl 3-[2-(dimethylamino)ethoxy]-2-methylpropanoate by the relative intensity of 2-(dimethylamino)ethyl 3-[2-(dimethylamino)ethoxy]-2-methylpropanoate. F3 is the value obtained by multiplying the peak area of methyl methacrylate by the relative intensity of methyl methacrylate. F4 is the value obtained by multiplying the peak area of 2-(dimethylamino)ethanol by the relative intensity of 2-(dimethylamino)ethanol. F5 is the value obtained by multiplying the peak area of methanol by the relative intensity of methanol. S0 is the peak area of 2-(dimethylamino)ethyl methacrylate.

[0040] <Example 2> to <Example 3>, <Comparative Example 1> Production of (meth)acrylate The transesterification reaction mixtures of Examples 2 and 3 and the comparative transesterification reaction mixture of Comparative Example 1 were obtained in the same manner as in Example 1, except that the N,N-dialkylalkanolamine and (meth)acrylic acid ester were changed to the compounds and amounts shown in Table 1, and the temperature at which the (meth)acrylic acid alkyl ester was added and the temperature and time conditions in the transesterification step were changed to those shown in Table 1. The product yield and by-product ratio were calculated for each of the transesterification reaction mixture and the comparative transesterification reaction mixture in the same manner as in Example 1, and are shown in Table 3.

[0041] In Example 2, 2-(dimethylamino)ethanol was replaced with 4-(dimethylamino)-1-butanol, 2-(dimethylamino)ethyl methacrylate with 4-(dimethylamino)butyl methacrylate, methyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate with methyl 3-[2-(dimethylamino)]butoxy]-2-methylpropanoate, and 2-(dimethylamino)ethyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate with 2-(dimethylamino)butyl 3-[2-(dimethylamino)]ethoxy]-2-methylpropanoate, respectively, and standard samples were prepared, analyzed by GC, and the product yield and proportion of by-products were calculated.

[0042] In Example 3, methyl methacrylate was changed to butyl methacrylate and methanol to butanol, respectively, and standard samples were prepared and analyzed by GC, and the product yield and proportion of by-products were calculated.

[0043] Comparative Example 2: Production of (meth)acrylic acid ester A mixture containing all raw materials was prepared by adding 150 g of 2-(dimethylamino)ethanol (Tokyo Chemical Industry Co., Ltd.), 250 g of methyl methacrylate (Tokyo Chemical Industry Co., Ltd.), 1.3 g of phenothiazine (Seiko Chemical Co., Ltd.) as a polymerization inhibitor, 0.8 g of dibutyltin oxide (Nitto Kasei Co., Ltd.) as a catalyst, and 0.8 g of 24 wt% sodium methoxide (methanol solution) (Nippon Soda Co., Ltd.) to a four-neck flask equipped with a stirrer, thermometer, air inlet, and Vigreux condenser. The mixture was heated, and the vaporized components (an azeotropic mixture of methanol and methyl methacrylate) were cooled and distilled off using the Vigreux condenser. Vaporization began when the reaction mixture temperature reached 94°C, and the vaporized components were distilled off while the Vigreux condenser overhead temperature was between 60 and 75°C. The temperature inside the reaction vessel was increased to remove the vaporized components by distillation, and heating was stopped when the temperature reached 120°C to terminate the transesterification reaction, thereby obtaining a comparative transesterification reaction mixture containing an amino group-containing (meth)acrylic acid ester (Table 2). The product yield and the proportion of by-products were calculated for the comparative transesterification reaction mixture obtained in the same manner as in Example 1, and the results are shown in Table 3.

[0044] [Table 1]

[0045] [Table 2]

[0046] [Table 3]

[0047] As can be seen from the comparison results between Examples 1 to 3 and Comparative Examples 1 and 2, the production method of the present invention makes it possible to produce an amino group-containing (meth)acrylic acid ester in high product yield while suppressing the generation of impurities, without using a large amount of an organotin compound as a transesterification catalyst. [Industrial Applicability]

[0048] According to the production method of the present invention, it is possible to provide a production method that can yield a high-purity amino group-containing (meth)acrylic acid ester.

Claims

1. A method for producing a (meth)acrylic acid ester, which comprises obtaining an amino group-containing (meth)acrylic acid ester by distilling off an alcohol from a reaction mixture containing an N,N-dialkylalkanolamine having 4 to 6 carbon atoms and an alkyl (meth)acrylate having 1 to 4 carbon atoms in the alkyl group and performing a transesterification reaction, the method for producing a (meth)acrylic acid ester having the following steps (1) to (2). (1) A step of heating a mixture containing an N,N-dialkylalkanolamine having 4 to 6 carbon atoms, a metal alkoxide, and an organotin compound and not containing an alkyl (meth)acrylate, and adding an alkyl (meth)acrylate at a temperature at which the temperature of the mixture is equal to or lower than the boiling point of the alcohol to be distilled off to obtain a reaction mixture (addition and mixing step). (2) A step of further heating after the addition and mixing step of (1) and distilling off the alcohol at a temperature at which the temperature of the reaction mixture exceeds the boiling point of the alcohol to be distilled off to perform a transesterification reaction (transesterification step).

2. The method for producing an aminoalkyl (meth)acrylate according to claim 1, wherein the molar ratio of the metal alkoxide to the organotin compound (number of moles of metal alkoxide: number of moles of organotin compound) is 0.8:1 to 1.2:1.

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