JP7655030B2 - Method for producing (meth)acrylic acid ester - Google Patents

Description

The present invention relates to a method for producing a hydroxybenzophenone-based compound by reacting a hydroxybenzophenone with a (meth)acrylic anhydride,
The present invention relates to a method for producing a (meth)acrylic acid ester of a hydroxybenzophenone.

As a method for producing a (meth)acrylic acid ester of a hydroxybenzophenone, Non-Patent Document 1 describes a method in which (meth)acrylic acid chloride is reacted with 4-hydroxybenzophenone in anhydrous acetone in the presence of triethylamine. This method generates hydrochloric acid and requires an amine in an amount equal to the moles of (meth)acrylic acid chloride and a large amount of solvent. Patent Document 1 describes a method in which (meth)acrylic anhydride is reacted using triethylamine. This method also requires an amine in an amount equal to the moles of (meth)acrylic anhydride and a large amount of solvent. Patent Document 2 describes a method in which (meth)acrylic anhydride is reacted in the presence of a catalytic amount of sulfuric acid, but since highly corrosive sulfuric acid is used, equipment made of highly corrosion-resistant materials must be used, and side reactions such as Friess transition and coloring of the reaction solution progress due to the action of sulfuric acid. Patent Document 3 describes a method in which (meth)acrylic anhydride is reacted using a catalytic amount of sodium methacrylate or sodium acetate. According to the study by the present inventors, it was found that in this method, the unsaturated bond of the methacryloyl group of the compound of formula (2) is subjected to an addition reaction with the carboxyl group of the methacrylic acid to generate a Michael adduct, resulting in a decrease in yield. Then, this Michael adduct is removed by purification,
It was found that when attempting to obtain a high-purity (meth)acrylic acid ester of a hydroxybenzophenone, the yield was significantly reduced.

JP 2003-261506 A Special Publication No. 2012-512216 Special Publication No. 2016-539913

(J. Appl. Polym. Sci., 57(8), 997 (1995))

The present invention aims to suppress the by-production of a Michael adduct, produce a (meth)acrylic ester of a hydroxybenzophenone in a high yield, and reduce the purification load in a method for producing a (meth)acrylic ester of a hydroxybenzophenone.

（式（１）中、Ｒ^１、Ｒ^２はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、炭素
数１～１０のアルキル基、または炭素数１～１０のアルコキシ基を示す。）

（式（２）中、Ｒ^１、Ｒ^２はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、炭素
数１～１０のアルキル基、または炭素数１～１０のアルコキシ基を示し、Ｒ^３は水素原子
またはメチル基を示す。）
［２］前記リチウム、マグネシウム、カルシウム、バリウム、ストロンチウムから選ばれ
る少なくとも一種の金属またはその塩および前記式（１）で表されるアルコール、前記（
メタ）アクリル酸無水物の合計質量に対し、３倍以下の溶媒を使用することを特徴とする
、［１］に記載の（メタ）アクリル酸エステルの製造方法。
［３］前記リチウム、マグネシウム、カルシウム、バリウム、ストロンチウムから選ばれ
る少なくとも一種の金属またはその塩および前記式（１）で表されるアルコール、前記（
メタ）アクリル酸無水物の合計質量に対し、１倍以下の溶媒を使用することを特徴とする
、［１］に記載の（メタ）アクリル酸エステルの製造方法。
［４］前記塩が酸化物、水酸化物、炭酸塩、炭酸水素塩、有機酸塩であることを特徴とす
る、［１］～［３］のいずれか一項に記載の（メタ）アクリル酸エステルの製造方法。
［５］前記塩がマグネシウム、カルシウムから選ばれる少なくとも一種の酸化物、水酸化
物、炭酸塩、炭酸水素塩、有機酸塩であることを特徴とする、［１］～［３］のいずれか
一項に記載の（メタ）アクリル酸エステルの製造方法。
［６］下記式（１）で表される構造を含み、総量１００％とした際にマイケル付加物が０
．５％以下である、下記式（２）で表される（メタ）アクリル酸エステル。

（式（１）中、Ｒ^１、Ｒ^２はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、炭素
数１～１０のアルキル基、または炭素数１～１０のアルコキシ基を示す。）

（式（２）中、Ｒ^１、Ｒ^２はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、炭素
数１～１０のアルキル基、または炭素数１～１０のアルコキシ基を示し、Ｒ^３は水素原子
またはメチル基を示す。） The above problems are solved by the present invention.
[1] A method for producing a (meth)acrylic acid ester represented by the following formula (2), which is obtained by reacting an alcohol represented by the following formula (1) with (meth)acrylic anhydride in the presence of at least one metal selected from the group consisting of lithium, magnesium, calcium, barium, and strontium, or a salt thereof:

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)

(In formula (2), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, and R ³ represents a hydrogen atom or a methyl group.)
[2] At least one metal selected from lithium, magnesium, calcium, barium, and strontium or a salt thereof and an alcohol represented by the formula (1),
The method for producing a (meth)acrylic acid ester according to [1], characterized in that a solvent is used in an amount three times or less than the total mass of (meth)acrylic anhydride.
[3] At least one metal selected from lithium, magnesium, calcium, barium, and strontium or a salt thereof and an alcohol represented by the formula (1),
The method for producing a (meth)acrylic acid ester according to [1], characterized in that a solvent is used in an amount equal to or less than 1 times the total mass of (meth)acrylic anhydride.
[4] The method for producing a (meth)acrylic acid ester according to any one of [1] to [3], wherein the salt is an oxide, a hydroxide, a carbonate, a hydrogencarbonate, or an organic acid salt.
[5] The method for producing a (meth)acrylic acid ester according to any one of [1] to [3], wherein the salt is at least one oxide, hydroxide, carbonate, hydrogencarbonate, or organic acid salt selected from magnesium and calcium.
[6] A compound having a structure represented by the following formula (1), the total amount of which is 100% and which contains no Michael adduct:
A (meth)acrylic acid ester represented by the following formula (2), in which the content of the (meth)acrylic acid ester is 0.5% or less:

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)

(In formula (2), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, and R ³ represents a hydrogen atom or a methyl group.)

According to the method for producing a (meth)acrylic acid ester of the present invention, it is possible to suppress the formation of Michael adducts and obtain a (meth)acrylic acid ester of a hydroxybenzophenone with few impurities in high efficiency and high yield. In addition, it is possible to reduce the purification load of the (meth)acrylic acid ester of a hydroxybenzophenone.

Hereinafter, an embodiment of the present invention will be described in detail.
In this specification, (meth)acrylic acid means acrylic acid and/or methacrylic acid. (Meth)acrylic anhydride means acrylic anhydride and/or methacrylic anhydride, and (meth)acrylic acid ester means acrylic acid ester and/or methacrylic acid ester. In addition, Michael adduct means a compound in which a carboxy group of (meth)acrylic acid is added to an unsaturated bond of a methacryloyl group or an acryloyl group of a (meth)acrylic acid ester represented by formula (2) by Michael addition.

（式（１）中、Ｒ^１、Ｒ^２はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、炭素
数１～１０のアルキル基、または炭素数１～１０のアルコキシ基を示す。）

（式（２）中、Ｒ^１、Ｒ^２はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、炭素
数１～１０のアルキル基、または炭素数１～１０のアルコキシ基を示し、Ｒ^３は水素原子
またはメチル基を示す。） In the present invention, an alcohol represented by the following formula (1) is reacted with (meth)acrylic anhydride to produce a (meth)acrylic ester represented by the following formula (2).

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)

(In formula (2), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, and R ³ represents a hydrogen atom or a methyl group.)

Examples of the alcohol represented by formula (1) include 2-hydroxybenzophenone, 2-hydroxy-5-methylbenzophenone, 2-hydroxy-4-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone, 5-chloro-2-hydroxybenzophenone,
5-chloro-2-hydroxy-4-methylbenzophenone, 4'-chloro-5-fluoro-2-hydroxybenzophenone, 4-allyloxy-2-hydroxybenzophenone,
2,4-dimethoxy-4'-hydroxybenzophenone, 2',5-dichloro-2-hydroxybenzophenone, 5-bromo-2-hydroxybenzophenone, 2-hydroxy-
4-n-octyloxybenzophenone, 3-hydroxybenzophenone, 4-fluoro-4'-hydroxybenzophenone, 4-chloro-4'-hydroxybenzophenone, 2
From the viewpoint of corrosiveness, structures not containing halogen atoms are preferred, and from the viewpoint of reaction rate, 4-hydroxybenzophenones are preferred. From the viewpoint of compound stability, R ¹ and/or R 2 are preferred.
Alternatively, ^R2 is preferably a hydrogen atom or an alkyl group. From the viewpoints of reaction rate and stability, 4-hydroxybenzophenone is most preferred.

The (meth)acrylic acid ester represented by the formula (2) can be produced by using lithium, magnesium,
The reaction is carried out in the presence of at least one metal selected from calcium, barium, and strontium or a salt thereof as a catalyst. From the viewpoint of the amount of Michael adduct by-product, at least one metal selected from lithium, magnesium, and calcium or a salt thereof is preferred. The salts include oxides, hydroxides, carbonates, hydrogen carbonates, sulfates, chlorides, nitrates, phosphates,
Examples of suitable salts include salts with inorganic acids such as borates; organic acid salts such as acetates, (meth)acrylates, and benzoates; and complex salts such as acetylacetonates and cyclopentadienyl complexes. From the viewpoint of activity, oxides, hydroxides, hydrogencarbonates, chlorides, and organic acid salts of lithium, magnesium, calcium, barium, and strontium are preferred, and oxides, hydroxides, carbonates, hydrogencarbonates, and organic acid salts are more preferred because they do not contain halogens. (Meth)
Acrylate salts are more preferred. These may be completely or partially dissolved. In the reaction, the above-mentioned catalyst compound may be used in the system. The catalyst may be used alone or in combination of two or more. Examples of the method of charging the catalyst into the reactor include a method of charging the entire amount into the reactor at the beginning, a method of charging a part of the catalyst at the beginning and feeding the remainder later, and the like.
The amount of the catalyst used is 0.0001 to 0.002 in terms of a molar ratio to the alcohol represented by formula (1).
From the viewpoint of smoothly proceeding with the reaction, the molar ratio is preferably 0.0005 times or more, and more preferably 0.001 times or more. On the other hand, from the viewpoint of removing the catalyst and suppressing side reactions,
This molar ratio is preferably 0.2 times or less, and more preferably 0.1 times or less.

The amount of (meth)acrylic anhydride used is preferably 0.5 to 5 times the amount of the alcohol represented by formula (1) in terms of molar ratio. From the viewpoint of the yield of the (meth)acrylic acid ester based on the alcohol, this molar ratio is preferably 0.9 or more, more preferably 1 or more, and even more preferably 1.1 or more.
From the viewpoint of reducing the load for treating the remaining (meth)acrylic anhydride at the end of the reaction, this molar ratio is preferably 2 times or less, more preferably 1.5 times or less, and even more preferably 1.3 times or less.

In the present invention, a solvent can be used. Examples of the solvent include hexane,
Aliphatic hydrocarbons such as heptane, pentane, cyclohexane, etc.; aromatic hydrocarbons such as toluene, xylene, etc.; ethers such as diethyl ether, diisopropyl ether, methyl tert-butyl ether, tetrahydrofuran, etc.; ketones such as acetone, methyl ethyl ketone, diisopropyl ketone, methyl isobutyl ketone, etc. can be used. In terms of solubility, ketones such as acetone, methyl ethyl ketone, diisopropyl ketone, methyl isobutyl ketone, etc. are preferred. The amount of the solvent used is at least one metal selected from lithium, magnesium, calcium, barium, and strontium or a salt thereof, and a solvent represented by the formula (1):
The amount of the solvent used is 0.01 to 10 times the total mass of the alcohol represented by the formula (I) and (meth)acrylic anhydride, but from the viewpoints of reaction rate and purification load, the amount of the solvent used is preferably 3 times or less, and more preferably 1 time or less. From the viewpoint of the dissolution amount, the amount of the solvent used is preferably 0.05 times or more, and more preferably 0.1 times or more.

The reaction temperature can be in the range of 0 to 130° C. In order to ensure that the reaction proceeds smoothly, the reaction temperature is preferably 20° C. or higher, and more preferably 40° C. or higher. On the other hand, in order to suppress polymerization and side reactions, the reaction temperature is preferably 110° C. or lower, and more preferably 90° C. or lower.

The reaction time may be appropriately determined based on the charge ratio and the reaction temperature, but is usually 0.5 to 48 hours. The time at which the conversion rate of the alcohol represented by formula (1) is 70% or more is preferable, and the time at which the conversion rate is 90% or more is more preferable. On the other hand, from the viewpoint of productivity, the reaction time is preferably 18 hours or less, more preferably 12 hours or less, and even more preferably 8 hours or less.

In the present invention, a polymerization inhibitor can be used. The polymerization inhibitor is introduced into the reactor, but it can also be introduced into the piping, the top of the reflux cooling tower, or midway through the tower.
Examples of the polymerization inhibitor include quinone-based polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, and benzoquinone; 2,6-di-tert-butylphenol; 2,4-di-
tert-Butylphenol, 2-tert-butyl-4,6-dimethylphenol, 2
alkylphenol-based polymerization inhibitors such as 2,4,6-di-tert-butyl-4-methylphenol and 2,4,6-tri-tert-butylphenol; alkylated diphenylamines;
, N'-diphenyl-p-phenylenediamine, phenothiazine, and other amine-based polymerization inhibitors, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-acetamino-2,2,6,6-tetramethylpiperidine-N-oxyl, and other hindered amine-based polymerization inhibitors, and copper dithiocarbamate-based polymerization inhibitors, such as copper metal, copper sulfate, copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, and other. These polymerization inhibitors may be used alone or in combination of two or more.
The amount of polymerization inhibitor added depends on the type and conditions, but is generally 0.01 to 0.01% by weight of the reaction solution.
It is used in the range of 1 to 10,000 ppm. In addition, by bubbling an oxygen-containing gas into the reaction liquid, the polymerization inhibition effect may be improved.

There are two ways to charge the raw materials into the reactor: 1) charging all the raw materials at once before the reaction;
1) A method in which one of the raw materials is charged entirely into a reactor, and the other raw material is charged after that, 2) A method in which one of the raw materials is charged entirely into a reactor, and the other raw material is charged partially, or 3) A method in which one of the raw materials is charged entirely into a reactor, and the other raw material is charged partially, or 4) A method in which all of the raw materials are charged partially. In the case of charging the raw materials partially, the remaining raw materials may be fed in portions or continuously after the start of the reaction.

Examples of reaction methods include a batch method in which all raw materials are charged into a single reactor and the reaction is completed, a continuous method in which raw materials are continuously fed into a reactor and reacted continuously, and a circulation method in which a reactor and a blending tank are provided and the raw materials are reacted in the reactor while circulating between the reactor and the blending tank. The reaction may be carried out while recovering the by-product (meth)acrylic acid. The pressure may be any of reduced pressure, atmospheric pressure, and pressurized pressure.
The reaction liquid can be subjected to treatments such as concentration, distillation, washing, treatment with an adsorbent, and crystallization to purify the (meth)acrylic acid ester represented by formula (2).

After the reaction is completed, if (meth)acrylic anhydride remains, it may be removed by a treatment such as distillation or extraction. It may be reacted with a compound such as water or alcohol that is easily reactive with (meth)acrylic anhydride to form a (meth)acrylic acid ester or (meth)acrylic acid, or it may be reacted with a basic substance and an acidic substance or an aqueous solution thereof to form (meth)acrylic acid or a salt of (meth)acrylic acid. The generated (meth)acrylic acid ester, (meth)acrylic acid, or salt of (meth)acrylic acid can be removed by the above-mentioned distillation, extraction, or washing. Examples of alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol,
Examples of the alcohol include linear or branched aliphatic alcohols such as tert-butyl alcohol, isobutyl alcohol, etc., unsaturated alcohols such as allyl alcohol, etc., cyclic alcohols such as cyclopentanol, cyclohexanol, etc., aromatic alcohols such as phenol, benzyl alcohol, etc., and polyhydric alcohols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, glycerin, etc. Among these alcohols, from the viewpoint of removing the generated (meth)acrylic acid ester, alcohols having 4 or less carbon atoms are preferred, and methyl alcohol or ethyl alcohol is more preferred.
The treatment temperature with alcohol is preferably in the range of 0 to 100° C. From the viewpoint of heat treatment time, the treatment temperature is more preferably 20° C. or higher, and further preferably 40° C. or higher. On the other hand, from the viewpoint of suppressing polymerization and side reactions, the treatment temperature is more preferably 100° C. or lower, and more preferably 80° C. or lower.
The treatment temperature when forming a salt of (meth)acrylic acid is preferably in the range of 0 to 100° C. From the viewpoint of heat treatment time, the treatment temperature is more preferably 10° C. or higher, and even more preferably 20° C. or higher. On the other hand, from the viewpoint of suppressing polymerization and side reactions, the treatment temperature is more preferably 80° C. or lower, and even more preferably 60° C. or lower.
The following is more preferred:

These treatments may be carried out while the catalyst and the like remain, or after they have been removed by washing or extraction as described below.
In these treatments, a solvent inert to the reaction may be used. Examples of the inert solvent include:
The amount of the solvent used may be 0.1 to 50 times the mass of the (meth)acrylic acid ester represented by formula (2).
The treatment time is usually 0.01 to 48 hours. In order to eliminate (meth)acrylic anhydride, the treatment time is preferably 0.1 hours or more, and more preferably 0.2 hours or more. In terms of suppressing polymerization and side reactions, the treatment time is preferably 24 hours or less, more preferably 12 hours or less, and even more preferably 6 hours or less.

Examples of the method for purifying the (meth)acrylic acid ester represented by formula (2) by distillation include simple distillation and distillation using a multi-stage distillation column (rectification column). Examples of the distillation column include Raschig rings, Lessing rings, etc. made of stainless steel, glass, ceramics, etc.
Packed towers using packings having shapes such as Dixon packing, Pall ring, saddle, and Sulzer packing, and plate towers such as perforated plate towers and bubble cap towers can be used. The distillation tower and the reactor can be connected in any of the following ways: the distillation tower is connected to the top of the reactor, the distillation tower is connected to the top of another vessel connected to the reactor, or the reactor is connected to any position from the top to the bottom of the distillation tower. In any of the connection ways, there may be one or more paths between the reactor and the distillation tower, and a device such as a heat exchanger may be interposed in the middle. In the distillation, an internal reflux method that does not use a reflux unit, or a method that uses a reflux unit to control the reflux ratio can be used.
The distillation temperature can be in the range of 10 to 250° C. From the viewpoint of suppressing polymerization and side reactions, the distillation temperature is preferably 200° C. or lower, more preferably 150° C. or lower. From the viewpoint of maintaining a sufficient amount of steam, the distillation temperature is preferably 40° C. or higher, more preferably 60° C. or higher.

Examples of a method for washing the (meth)acrylic acid ester represented by formula (2) include a method for washing with water, an aqueous solution of a salt such as table salt or sodium sulfate, or an aqueous solution of a basic substance. Examples of basic substances include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, hydroxides of alkaline earth metals such as calcium hydroxide and magnesium hydroxide,
Examples of the basic substance include alkali metal carbonates such as sodium carbonate and potassium carbonate; alkaline earth metal carbonates such as calcium carbonate and magnesium carbonate; alkali metal bicarbonates such as sodium bicarbonate and potassium bicarbonate; alkaline earth metal bicarbonates such as calcium bicarbonate and magnesium bicarbonate; and organic bases such as pyridine, 4-(dimethylamino)pyridine, and triethylamine. Two or more of these basic substances can be used in combination. Washing can be performed once or multiple times. Furthermore, washing can be performed multiple times with aqueous solutions of different basic substances. After washing with the basic substance, washing with water is preferably performed to remove the basic substance remaining in the organic layer. The water used for washing is preferably distilled water or pure water deionized with an ion exchange resin or the like.

Furthermore, before washing with the aqueous solution of a basic substance, washing with water or an aqueous solution of an acidic substance may be performed. Examples of the acidic substance include inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, boric acid, hydrochloric acid, and heteropolyacids, and organic acids such as acetic acid, methanesulfonic acid, paratoluenesulfonic acid, and camphorsulfonic acid.

A solvent may be used when washing the (meth)acrylic acid ester represented by formula (2). As the solvent, any of the above-mentioned solvents that dissolve in 100 g of water in an amount of 20 g or less can be used. The mass of the solvent is preferably 0.1 to 30 times, more preferably 0.5 to 5 times, the mass of the reaction liquid. If the amount of the solvent is small, the (meth)acrylic acid ester represented by formula (2) may be easily dissolved in the water or aqueous solution used for washing.
Acrylic acid esters may migrate. If the amount is large, a large reactor is required and the time and energy required for concentration increases.

Examples of the method for reducing the amount of impurities by treating the (meth)acrylic acid ester represented by formula (2) with an adsorbent include column chromatography and a method in which the adsorbent is suspended to adsorb the impurities and then the adsorbent is separated. Examples of the adsorbent include activated clay, hydrotalcites, porous polymers, ion exchange resins (cation exchange resins or anion exchange resins), activated carbon, adsorption resins, silica gel, silica-alumina-based adsorbents, alumina gel, activated alumina, silicon dioxide, and zeolite. The amount of the adsorbent used is 0.05 to 20% by mass based on the (meth)acrylic acid ester represented by formula (2). In particular, 0.5 to 10% by mass is preferred. If the amount is too small, the effect of reducing impurities is not sufficient, and if the amount is too large, the amount of the adsorbent with respect to the adsorbent of formula (2) is too large.
As a result, the total adsorption amount of the (meth)acrylic acid ester represented by formula (2) increases, and the loss due to adsorption of the (meth)acrylic acid ester represented by formula (2) and the load when separating the adsorbent by filtration or the like become large. The temperature when the (meth)acrylic acid ester represented by formula (2) is contacted with the adsorbent is not particularly limited, but is usually 0 to 100°C. From the viewpoint of suppressing side reactions during treatment, the temperature when contacting is preferably 60°C or less, particularly 40°C or less. The time when the reaction liquid is contacted with the adsorbent varies depending on the type of adsorbent and the amount used, but is usually
The time is preferably about 1 to 120 minutes, and particularly preferably about 3 to 60 minutes.

After the adsorption treatment with the adsorbent, the (meth)acrylic acid ester represented by formula (2) and the adsorbent can be separated by a method such as filtration. Examples of the filter include membrane filters made of fluororesins such as polytetrafluoroethylene. A solvent may be used when contacting the (meth)acrylic acid ester represented by formula (2) with the adsorbent. As the solvent, those listed above can be used. The mass of the solvent is preferably 0.1 to 30 times, more preferably 0.5 to 5 times, the mass of the reaction liquid.

Examples of the method for crystallizing the (meth)acrylic acid ester represented by formula (2) include a method of dissolving the ester in a solvent and then lowering the temperature of the solution to precipitate crystals, a method of concentrating the solution to precipitate crystals, and a method of adding a solvent with low solubility to the (meth)acrylic acid ester solution represented by formula (2). Examples of the solvent include the same as those described above. Two or more of these may be mixed and used. A solvent may be used when crystallizing the ester. Examples of the solvent include those described above. The mass of the solvent is preferably 0.1 to 30 times, more preferably 0.5 to 5 times, the mass of the reaction solution.

The present invention will be described in detail below with reference to examples.
The following examples are not intended to be limiting.
The measurement and evaluation methods used in the present invention are as follows.

In the examples, analysis was performed by gas chromatography (hereinafter, abbreviated as GC) under the following conditions using anisole as an internal standard and acetone as a dilution solvent.
Column: J&B Scientific DB-1, length 30m x inner diameter 0.53
mm
Film thickness: 3 μm
Injection temperature: 200°C
Detector temperature: 250°C
Column temperature and time: 60°C for 1 minute, heated at 10°C/min, held at 250°C

4-Hydroxybenzophenone and 4-methacryloyloxybenzophenone were quantified by a calibration curve method, and the conversion rate and the yield based on 4-hydroxybenzophenone were calculated.
The yield of the Michael adduct in which methacrylic acid was added to the methacryloyl group of 4-methacryloyloxybenzophenone was calculated from the GC peak area of each compound according to the following formula.
A: GC peak area of Michael adduct B: GC peak area of 4-hydroxybenzophenone C: GC peak area of 4-methacryloyloxybenzophenone Michael adduct yield (%) = A/(A+B+C) x 100

Example 1
Into a five-neck flask equipped with a reflux condenser, 18.5 g (0.12 mol) of distilled and purified methacrylic anhydride (manufactured by Aldrich Co., Ltd.), 19.8 g (0.1 mol) of 4-hydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.20 g (0.005 mol) of heavy magnesium oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 5 g of methyl isobutyl ketone,
10 mg of 2,6-di-tert-butyl-p-cresol (Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was heated in an oil bath and reacted at 80° C. for 5 hours. The liquid after the reaction was analyzed, and the following was found:
The conversion of 4-hydroxybenzophenone was 99.8%, the yield of 4-methacryloyloxybenzophenone (MBP) was 99.5%, and the yield of the Michael adduct was 0.2%.

(Examples 2 to 14)
The heavy magnesium oxide in Example 1 was replaced with 0.005 mol of the catalyst shown in Table 1.
The liquid after the reaction was analyzed and the results are shown in Table 1.

(Comparative Examples 1 to 4)
The heavy magnesium oxide in Example 1 was replaced with 0.005 mol of the catalyst shown in Table 1.
The liquid after the reaction was analyzed and the results are shown in Table 1.

Details of each catalyst in the table are as follows:
- Heavy magnesium oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・Lithium hydroxide (Tokyo Chemical Industry Co., Ltd.)
・Lithium carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・Lithium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
- Magnesium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・Magnesium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Magnesium acetate tetrahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
- Magnesium methacrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・Calcium oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Calcium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・Calcium methacrylate (Tokyo Chemical Industry Co., Ltd.)
- Barium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Strontium hydroxide (Sigma-Aldrich)
4-Dimethylaminopyridine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・Sodium methoxide (Tokyo Chemical Industry Co., Ltd.)
・Sodium carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・Calcium carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

(Examples 15 to 19)
The same procedure as in Example 1 was carried out, except that the heavy magnesium oxide in Example 1 was replaced with 0.0005 mol of the catalyst shown in Table 2, methyl isobutyl ketone was not used, and the reaction was carried out at 90° C. for 5 hours. The results of analysis of the liquid after the reaction are shown in Table 2.

(Example 20)
The same operation as in Example 1 was carried out, except that the heavy magnesium oxide in Example 1 was changed to 0.0001 mol, methyl isobutyl ketone was not used, and the reaction was carried out at 90° C. for 7 hours. Analysis of the liquid after the reaction showed that the 4-hydroxybenzophenone conversion was 99.4%, the 4-methacryloyloxybenzophenone (MBP) yield was 99.2%, and the Michael adduct yield was 0.1%.

(Example 21)
The same operation as in Example 1 was carried out, except that 38.5 g of methyl isobutyl ketone was added initially as a solvent. The liquid after the reaction was analyzed, and as a result, the conversion of 4-hydroxybenzophenone was 99.2%, the yield of 4-methacryloyloxybenzophenone (MBP) was 99.0%, and the yield of Michael adduct was 0.2%.

(Comparative Example 5)
In Comparative Example 3, except that 120 g of methyl isobutyl ketone was added initially,
The reaction mixture was analyzed, and the conversion rate of 4-hydroxybenzophenone was 66.1%, and the yield of 4-methacryloyloxybenzophenone (MBP) was 63.8%.
The Michael adduct yield was 2.0%.

In all of Examples 1 to 21, the 4-hydroxybenzophenone conversion rate and the 4-methacryloyloxybenzophenone (MBP) yield were very high, and the Michael adduct yield was kept low. On the other hand, in Comparative Examples 1 to 5, in which a catalyst different from that of the present invention was used, the 4-methacryloyloxybenzophenone (MBP) yield was low, and a large amount of Michael adduct was by-produced.

From the above examples, it is apparent that the production method of the present invention exhibits excellent 4-hydroxybenzophenone conversion and 4-methacryloyloxybenzophenone (MBP) yield, sufficiently suppresses the by-production of Michael adducts, and enables a reduction in the purification load.

Claims (4)

A method for producing a (meth)acrylic acid ester represented by the following formula (2), which is obtained by reacting an alcohol represented by the following formula (1) with (meth)acrylic anhydride in the presence of magnesium (meth)acrylate:

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)

(In formula (2) and formula (1), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, and R ³ represents a hydrogen atom or a methyl group.) 2. The method for producing a (meth)acrylic ester according to claim 1, wherein a solvent is used in an amount three times or less than a total mass of the magnesium (meth)acrylate, the alcohol represented by the formula (1), and the (meth)acrylic anhydride. 2. The method for producing a (meth)acrylic acid ester according to claim 1, wherein a solvent is used in an amount equal to or less than 1 times the total mass of the magnesium (meth)acrylate, the alcohol represented by the formula (1), and the (meth)acrylic anhydride. A reaction product of an alcohol represented by the following formula (1) and (meth)acrylic anhydride , the reaction product containing a (meth)acrylic acid ester represented by the following formula (2), wherein in a gas chromatography analysis of the reaction product, a ratio of a peak area of the Michael adduct to a total ( 100% ) of a peak area of a Michael adduct of the alcohol, a peak area of the alcohol , and a peak area of the (meth)acrylic acid ester is 0.1 % or less.

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)

(In formula (2) and formula (1), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, and R ³ represents a hydrogen atom or a methyl group.)