JP2002234859A - Method for producing (meth)acrylic ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a highly pure (meth)acrylic ester in a high reaction rate by using an inexpensive solid catalyst which can easily be separated from the product on the finish of the reaction, and to provide a method for producing the (meth)acrylic ester, while effectively preventing the polymerization of the (meth)acrylic ester. SOLUTION: This method for producing the (meth)acrylic ester, comprising the ester interchange reaction of a (meth)acrylic ester with a 3 to 20C alcohol, is characterized by using one or more of calcium oxide, calcium hydroxide, magnesium oxide and magnesium hydroxide and one or more of the hydroxide, halide, carbonate, hydrogen carbonate, carboxylate or alkoxide of sodium or potassium, as catalysts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a (meth) acrylate ester by a transesterification method.

[0002]

2. Description of the Related Art Metal catalysts such as titanium catalysts and tin catalysts, p-toluenesulfonic acid, sulfuric acid, and strongly acidic ion exchange resins are used in the transesterification reaction between (meth) acrylate and alcohols. Such acid catalysts or strongly basic ion exchange resins are known. These catalysts are classified into homogeneous catalysts which dissolve in the reaction solution themselves and heterogeneous catalysts which do not dissolve in the reaction solution.

When a homogeneous catalyst typified by titanium alkoxide is used, the catalyst itself dissolves in the reaction solution, and after the reaction, a separation operation such as distillation is required to separate the product from the catalyst.

On the other hand, when a strongly acidic ion exchange resin or a strongly basic ion exchange resin, which is a heterogeneous catalyst, is used, the separation of the catalyst is easy, but generally the activity or selectivity of the reaction is low and Separation operations such as distillation are required to separate impurities such as olefins generated by dehydration of a part of alcohols. In addition, such impurities not only lower the purity of the reaction solution but also are removed as unnecessary substances, and thus have a problem of lowering the raw material yield and generating waste liquid.

[0005] In order to solve these problems, various heterogeneous solid catalysts have been developed. As a method for producing a (meth) acrylate ester by a transesterification method using an inorganic base as a catalyst, for example, JP-A-50-142
No. 513 discloses a method for producing dimethylaminoethyl (meth) acrylate using calcium hydroxide or calcium oxide as a catalyst, and JP-A-61-50940 discloses a method using a calcium-containing compound and a lithium-containing compound as catalysts. A method for producing a (meth) acrylate is disclosed. Also, Japanese Patent Application Laid-Open No. 56-77242
Japanese Patent Application Publication No. JP-A-2003-115122 discloses a method for producing butyl methacrylate using sodium hydroxide and / or potassium hydroxide as a catalyst.

However, Japanese Patent Application Laid-Open No. 50-142513
In the method described in the publication, the activity of the catalyst is not always sufficient, and in order to obtain a satisfactory activity, it may be necessary to use a large amount of the catalyst or to carry out the reaction for a long time. Further, in the method described in JP-A-61-50940, a sufficient yield may not be obtained in some cases. Also,
In the method described in JP-A-56-77242, the catalyst may be deactivated during the reaction, and the progress of the reaction may be stopped.

Further, depending on the selection of the polymerization inhibitor, the polymerization of the (meth) acrylate ester proceeds during the reaction,
The reaction solution at the end of the reaction may be colored, and then a purification operation such as washing and distillation may be required. Therefore, there is a need for a method that can more effectively prevent polymerization.

[0008] Usually, after the transesterification reaction is performed using these catalysts, the catalyst is separated by filtration or the like.
Trace metals derived from the catalyst may be mixed into the reaction solution,
Operations such as washing and distillation may be required for the removal. It is industrially advantageous if trace metals derived from the catalyst can be removed more easily than by washing or distillation.

[0009]

SUMMARY OF THE INVENTION The present invention provides a method for producing a high-purity (meth) acrylic acid ester at a high conversion using an inexpensive solid catalyst which can be easily separated from the product at the end of the reaction. An object of the present invention is to provide a method for producing a (meth) acrylic ester by effectively preventing polymerization of the (meth) acrylic ester.

[0010]

The above object of the present invention can be solved by the following present invention. (A) (meth) acrylic acid ester, having 3 to 20 carbon atoms
By transesterification with alcohols (meth)
A method for producing an acrylate ester, as a catalyst, calcium oxide, calcium hydroxide, one or more of magnesium oxide or magnesium hydroxide,
Sodium or potassium hydroxide, halide,
A method for producing a (meth) acrylic ester, wherein the transesterification reaction is carried out using at least one of a carbonate, a hydrogen carbonate, a carboxylate and an alkoxide. (B) N represented by the following general formula (1) as a polymerization inhibitor
-Oxyl compound, N-oxyl compound represented by the following general formula (2) or cyclohexane-1-spiro-2 '-(4'-oxoimidazolidin-1'-oxyl) represented by the following general formula (3)- (A) The method for producing a (meth) acrylate according to the above (A), wherein the transesterification reaction is carried out using at least one of 5′-spiro-1 ″ -cyclohexane.

[0011]

Embedded image (In the general formula (1), R ¹ , R ² , R ³ and R ^{4 each} have 1 to 8 carbon atoms.
And may be linear or branched, and R ¹
And R ² , and R ³ and R ⁴ may form a ring with each other. R ⁵
Is H, OH, OR, OCOR, NHCOR or O-
[(EO) _n + (PO) _m ] -H, R ⁶ is H, and R ⁵ and R ⁶ together may be ＯO. EO represents an ethyleneoxy group, PO represents a propyleneoxy group, n and m are the same or different integers from 0 to 10, and n and m are not simultaneously 0.
R is a hydrogen atom or an alkyl group, an alkenyl group or an aryl group having 1 to 18 carbon atoms. The alkyl group may be linear or branched, and the aryl group may be a hydrogen atom substituted with an alkyl group.

In the general formula (2), R ²¹ , R ²² , R ²³ , R ²⁴
Is an alkyl group having 1 to 8 carbon atoms and may be linear or branched, and R ²¹ and R ²² , and R ²³ and R ²⁴ may form a ring with each other. R ²⁵ is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, an alkenyl group or an aryl group; the alkyl group may be linear or branched; and the aryl group may be a hydrogen atom substituted with an alkyl group. . (C) The above (A) or (B), wherein the (meth) acrylic acid ester obtained by the transesterification reaction is further subjected to removal of trace amounts of metal and a polymerization inhibitor using a solid adsorbent. The method for producing a (meth) acrylic acid ester according to the above).

The solid adsorbent is preferably at least one of activated clay, activated carbon, silica gel and a strongly acidic ion exchange resin.

[0014]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, one or more of calcium oxide, calcium hydroxide, magnesium oxide or magnesium hydroxide and a sodium or potassium hydroxide, halide, carbonate, hydrogencarbonate are used as catalysts. A transesterification reaction between a (meth) acrylic ester and an alcohol having 3 to 20 carbon atoms is performed using at least one of a carboxylic acid salt and an alkoxide.

By performing a transesterification reaction using such a catalyst, a high-purity (meth) acrylic ester can be produced at a high conversion. After the reaction is completed, the catalyst can be easily separated from the reaction solution in a short time by a simple operation such as filtration.

As the catalyst, it is important to use a calcium-containing compound and / or a magnesium-containing compound and a sodium-containing compound and / or a potassium-containing compound. If only one is used,
The reaction time becomes longer, which may lead to a decrease in productivity or progress of polymerization.

Further, in the present invention, N is used as a polymerization inhibitor.
-Oxyl compound, specifically, an N-oxyl compound represented by the above general formula (1), an N-oxyl compound represented by the above general formula (2), or cyclohexane-1-spiro represented by the above general formula (3) -2 '-(4'-oxoimidazolidin-1'-oxyl) -5'-spiro-
It is preferable to use any one or more of 1 ″ -cyclohexane.

The N-oxyl compound has an extremely high polymerization inhibitory effect as compared with commonly used phenol or amine polymerization inhibitors such as hydroquinone and hydroquinone monomethyl ether, and the reaction solution after the reaction is hardly colored. . Further, even if the N-oxyl compound reacts with an excess of (meth) acrylate in the system, the effect of preventing polymerization is hardly impaired. Moreover,
An N-oxyl compound is expected to have an excellent polymerization inhibitory effect in a small amount.

The (meth) acrylate obtained by the transesterification reaction is preferably purified using a solid adsorbent. By using a solid adsorbent, trace amounts of metal and a polymerization inhibitor can be easily removed. As the solid adsorbent to be used, any one or more of activated clay, activated carbon, silica gel and a strongly acidic ion exchange resin is preferable.

Hereinafter, the present invention will be described in detail.

The raw material (meth) acrylate used in the present invention is not particularly limited. However, it is easy to remove the alcohol by-produced from the raw material (meth) acrylate during the reaction to the outside of the system. Acrylic acid esters are preferred, and for example, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and the like, particularly methyl (meth) acrylate, are preferably used.

Here, "(meth) acrylate" means "acrylate" and "methacrylate" as commonly used.

In the present invention, the alcohol to be reacted with the (meth) acrylate has 3 to 20 carbon atoms, and the alcohol includes phenol. In addition,
The alcohol may further have a substituent, and the carbon chain may be linear, branched, or cyclic.
The alcohol may be a primary alcohol, a secondary alcohol, or a tertiary alcohol.

Alcohols include alcohols,
Alkoxyalkanols, alkenoxyalkanols, alkenols, phenols, phenoxyalkanols, cycloalkanols, alkylcycloalkanols, cycloalkylalkanols, phenylalkanols, alkylphenylalkanols, haloalkanols, cyanoalkanols And aminoalkanols.

The phenols include not only those having one benzene ring but also those having two or more benzene rings such as naphthol. Further, the phenol may have one or more substituents other than the hydroxy group.

Among such alcohols, alkanols, alkenols and aminoalkenols are preferred, and alkanols are particularly preferred.

As the alcohols, specifically, n-
Propanol, isopropanol, n-butanol, isobutanol, tertiary butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol, tridecanol, dimethylaminoethanol, diethylamino Ethanol, cyclohexanol, 3,3,5-trimethylcyclohexanol, 4-tert-butylcyclohexanol, phenol, benzyl alcohol, 1-phenylethyl alcohol, 2-phenylethyl alcohol, phenoxyethanol, methoxyethanol, ethoxyethanol, butoxyethanol , Allyl alcohol, methallyl alcohol, phenol, benzyl alcohol, etc., but are not limited thereto. Not intended to be.

The mixing ratio of the (meth) acrylate and the alcohol can be arbitrarily set. From the viewpoint of the productivity of the target compound, the (meth) acrylate is usually prepared by mixing the alcohol (1) with the alcohol (1). 0.1 to 10 mol, preferably 0.3 mol or more, or 4
Mol or less.

In the present invention, as a catalyst, one or more of calcium oxide, calcium hydroxide, magnesium oxide or magnesium hydroxide (calcium-containing compound and / or magnesium-containing compound), sodium or potassium hydroxide, halogen Or any one or more of a compound, a carbonate, a hydrogen carbonate, a carboxylate and an alkoxide (a sodium-containing compound and / or a potassium-containing compound). Any one of calcium oxide, calcium hydroxide, magnesium oxide, and magnesium hydroxide may be used, or a mixture of any two or more of them may be used. In addition, sodium hydroxide, halide, carbonate, hydrogen carbonate, carboxylate or alkoxide, potassium hydroxide, halide, carbonate, hydrogen carbonate, carboxylate or alkoxide is any one kind. May be used, or a mixture of any two or more of them may be used.

The calcium-containing compound and / or the magnesium-containing compound are preferably calcium oxide and calcium hydroxide.

Specific examples of the sodium-containing compound and / or potassium-containing compound include sodium hydroxide,
Sodium fluoride, sodium chloride, sodium bromide,
Sodium iodide, sodium carbonate, sodium bicarbonate, sodium acetate, sodium methylate, potassium hydroxide, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, potassium carbonate, potassium hydrogencarbonate, potassium acetate, potassium methylate And the like. Among them, sodium hydroxide and potassium hydroxide are preferred.

In the present invention, commercially available calcium oxide, calcium hydroxide, magnesium oxide and magnesium hydroxide may be used as they are, but calcium oxide and magnesium oxide are calcined at an arbitrary temperature under the flow of an oxygen-containing gas. It may be used afterwards.

As the sodium or potassium hydroxide, halide, carbonate, hydrogencarbonate, carboxylate or alkoxide, commercially available products can be used as they are, but they may be used by dissolving them in water or raw material alcohols in advance. You may.

In the case of a batch reaction, the total content of calcium and magnesium in the catalyst used is usually 0.0001 to 0.5 mol, preferably 0.001 mol or more or 0 mol or more per mol of alcohol. .25 mol or less. The total content of sodium and potassium in the catalyst used is usually 0.0 to 1 mol of alcohol.
001 to 0.5 mol, preferably 0.001 mol or more or 0.25 mol or less. If the amount of the catalyst used is too small, the productivity may decrease due to a decrease in the yield of the (meth) acrylic acid ester, an increase in the amount of unreacted product recovered, or an increase in the reaction time. On the other hand, if the amount of the catalyst used is too large, the yield of the (meth) acrylic acid ester, the reaction time and the like may not be largely changed.

The molar ratio of the total content of calcium and magnesium to the total content of sodium and potassium in the catalyst used can be set arbitrarily, but is usually 5:95 to 95: 5, preferably 1:95. : 9 to 9: 1.

As to the method of adding the catalyst to the reaction solution, these catalysts may be added after being mixed in advance, or the respective catalysts may be sequentially added in an arbitrary order.

In the present invention, as the mode of the transesterification reaction using the above-mentioned catalyst, generally used techniques such as a fluidized bed type, a fixed bed type, a stirring type or a reactive distillation type can be used. Any of batch type methods may be used.

Further, since the catalyst used in the present invention is a solid catalyst, separation of the reaction solution and the catalyst is extremely easy. That is, when the reaction is performed using a batch reactor, the catalyst can be separated by filtering or decanting the reaction solution after completion of the reaction. In addition, the separated catalyst can be used repeatedly for transesterification. In the case of using a tubular flow reactor, only the reaction liquid can be taken out by filling the reactor with a catalyst and forming a fixed bed.

In the present invention, the reaction pressure for carrying out the transesterification is not particularly limited, and the reaction can be carried out under any of reduced pressure, normal pressure and pressurized pressure. In addition, the reaction temperature is not particularly limited, and can be freely set to be equal to or lower than the boiling point temperature of the reaction solution at the set pressure. The reaction temperature is preferably higher from the viewpoint of reaction kinetics, and is preferably 150 ° C. or lower from the viewpoint of preventing polymerization.

The alcohol by-produced from the raw material (meth) acrylate with the progress of the reaction is usually removed out of the system in order to advance the reaction. It can be taken out of the reaction system as an azeotrope.

In the present invention, it is preferable to add a polymerization inhibitor during the transesterification reaction.

As the polymerization inhibitor used in the present invention, an N-oxyl compound, specifically, an N-oxyl compound represented by the following general formula (1) and an N-oxyl compound represented by the following general formula (2)
-Oxyl compounds, and cyclohexane-1-spiro-2 ′-(4′-oxoimidazolidin-1′-oxyl) -5′-spiro-1 ″ -cyclohexane represented by the following general formula (3) are preferred.

[0043]

Embedded image The N-oxyl compound represented by the general formula (1) will be described.

R ¹ , R ² , R ³ and R ⁴ in the general formula (1) are
It is an alkyl group having 1 to 8 carbon atoms. The alkyl group may be linear or branched. R ¹ and R ² and R ³ and R ⁴ may form a ring with each other.

[0045] As the ^{R 1, R 2, R 3} , R 4, 1~ carbon atoms
5 straight-chain or branched alkyl groups are preferred, and a methyl group,
Preferable examples include an ethyl group, a propyl group and a butyl group. Among them, a methyl group and an ethyl group are preferable.
It is particularly preferred that all of R ¹ , R ² , R ³ and R ⁴ are methyl groups.

R ⁵ in the general formula (1) is H, OH, O
R, OCOR, NHCOR or O-[(EO) _n +
(PO) _m] is -H, R ⁶ is H, or, R ⁵
And R ⁶ together may be = 0.

Here, R is a hydrogen atom or a group having 1 to 1 carbon atoms.
8 is an alkyl group, an alkenyl group or an aryl group. The alkyl group may be linear or branched. The aryl group may have a hydrogen atom substituted with an alkyl group.

EO represents an ethyleneoxy group, PO represents a propyleneoxy group, n and m are the same or different integers from 0 to 10, and n and m are not simultaneously 0.

The group O-[(EO) _{n of the} general formula (1)
+ (PO) _m ] -H, the arrangement of the ethyleneoxy group and the propyleneoxy group can be freely selected. For example, when the ethyleneoxy group and the propyleneoxy group are randomly arranged with respect to each other, or even when each is divided into several blocks and arranged, the sum of the number of ethyleneoxy groups is The case where n is the sum of the number of propyleneoxy groups is m is included in this notation.

As R ⁵ , H, OH and R are OR such as methyl, ethyl, propyl, phenyl and benzyl, and R is OCO such as methyl, ethyl, benzyl, vinyl and allyl.
R, R is NHC such as methyl, ethyl, vinyl, propyl, etc.
OR and O-[(EO) _n + excluding hydrogen of a hydroxyl group such as diethylene glycol, triethylene glycol, tetraethylene glycol and dipropylene glycol.
(PO) _m ] -H.

As R ⁶ , H is preferable.

More specifically, N- represented by the general formula (1)
Examples of oxyl compounds include 2,2,6,6-tetrame
Tylpiperidine-N-oxyl, 4-hydroxy-2,
2,6,6-tetramethylpiperidine-N-oxyl,
4-acetyloxy-2,2,6,6-tetramethylpi
Peridine-N-oxyl, 4-acryloyloxy-
2,2,6,6-tetramethylpiperidine-N-oxy
4-methacryloyloxy-2,2,6,6-tetra
Lamethylpiperidine-N-oxyl, 4-benzoylo
Xy-2,2,6,6-tetramethyl-piperidine-N
-Oxyl, 4-methoxy-2,2,6,6-tetrame
Tylpiperidine-N-oxyl, 4-ethoxy-2,
2,6,6-tetramethylpiperidine-N-oxyl,
4-phenoxy-2,2,6,6-piperidine-N-O
Xyl, 4-benzyloxy-2,2,6,6-tetra
Methylpiperidine-N-oxyl, 4-acetylamino
-2,2,6,6-tetramethylpiperidine-N-oxo
Sil, 4-acryloylamino-2,2,6,6-tet
Lamethylpiperidine-N-oxyl, 4-methacryloy
Ruamino-2,2,6,6-tetramethylpiperidine-
N-oxyl, 4-benzoylamino-2,2,6,6
-Tetramethylpiperidine-N-oxyl, 4-cinna
Moylamino-2,2,6,6-tetramethylpiperidi
-N-oxyl, 4-crotonylamino-2,2,
6,6-tetramethylpiperidine-N-oxyl, 4-
Propionylamino-2,2,6,6-tetramethylpi
Peridine-N-oxyl, 4-butyrylamino-2,
2,6,6-tetramethylpiperidine-N-oxyl,
2,2,6,6-tetramethyl-4-piperidone-N-
Oxyl, 4- [H- (EO)_Two-O] -2, 2, 6,
6-tetramethylpiperidine-N-oxyl, 4- [H
-(EO)_Four—O] -2,2,6,6-tetramethylpi
Peridine-N-oxyl, 4- [H- (EO)₆-O]
-2,2,6,6-tetramethylpiperidine-N-oxo
Syl, 4- [H- (EO)₈-O] -2,2,6,6-
Tetramethylpiperidine-N-oxyl, 4- [H-
(EO)_Ten-O] -2,2,6,6-tetramethylpipe
Lysine-N-oxyl, 4- [H-[(EO) _Two+ (P
O)_Four] -O] -2,2,6,6-tetramethylpiperi
Gin-N-oxyl, 4- [H-[(EO)_Four+ (P
O)_Three] -O] -2,2,6,6-tetramethylpiperi
Gin-N-oxyl, 4- [H-[(EO)₆+ (P
O)_Three] -O] -2,2,6,6-tetramethylpiperi
Gin-N-oxyl, 4- [H- (PO)_Ten-O]-
2,2,6,6-tetramethylpiperidine-N-oxy
4- [H- (PO)₆-O] -2,2,6,6-te
Tramethylpiperidine-N-oxyl, 4- [H-
[(EO)_Five+ (PO)_Ten] -O] -2,2,6,6-
Tetramethylpiperidine-N-oxyl and the like.
However, the present invention is not limited to these. Table 1 and Table 2
Representative of these compounds and other oxyl compounds
Here is an example.

[0053]

[Table 1]

[0054]

[Table 2] Next, the N-oxyl compound represented by the general formula (2) will be described.

R in the general formula (2)^{twenty one}, R^{twenty two}, R^{twenty three}, R^{twenty four}
Is R in the general formula (1)¹, R^Two, R ^Three, R^FourSimilar to
And the same applies to preferred ones.

R ²⁵ in the general formula (2) is a hydrogen atom or an alkyl, alkenyl or aryl group having 1 to 18 carbon atoms. The alkyl group may be linear or branched.
The aryl group may have a hydrogen atom substituted with an alkyl group.

R ²⁵ represents a hydrogen atom, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, Tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, phenyl group, biphenyl group,
And a naphthyl group.

Specifically, N- represented by the general formula (2)
Examples of the oxyl compound include 3-dodecyl-8-oxyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro [4.5] decane-2,4-dione (hereinafter, referred to as “oxyl compound”).
Abbreviated as compound 32), 3-octyl-8-oxyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro [4.5] decane-2,4-dione, 8-oxyl- Examples include, but are not limited to, 7,7,9,9-tetramethyl-1,3,8-triazaspiro [4.5] decane-2,4-dione.

Further, cyclohexane-1-spiro-2 ′-(4′-oxoimidazolidin-1′-oxyl) -5′-spiro-1 ″ -cyclohexane (hereinafter, referred to as formula (3)) Compound 33) may be used.

These N-oxyl compounds may be used alone or in combination of two or more.

The N-oxyl compound used in the present invention is particularly preferably 4-acetyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl.

The mass of the N-oxyl compound to be used is usually 0.01 to 5000 ppm, preferably 0.1 ppm or more, based on the mass of the target (meth) acrylate.
Particularly, it is preferably at least 1 ppm, more preferably at most 1,000 ppm, particularly preferably at most 100 ppm. If the amount of the N-oxyl compound is too small, it may be difficult to obtain a sufficient polymerization inhibitory effect, and the yield of the product (meth) acrylate may decrease. On the other hand, N
-Even if the amount of the oxyl compound is too large, a large difference in the polymerization preventing effect may not be recognized.

In the present invention, the transesterification reaction is carried out as described above, and in the case of a batch reaction, the catalyst is separated by filtration or decantation, and then the unreacted (meth) acrylic acid ester and alcohol as raw materials are separated from the reaction solution. The (meth) acrylic acid ester can be obtained by distilling off the compounds. Further, distillation and purification and / or washing operations may be performed to obtain a higher-purity target substance.

Further, as a simpler method, purification can be performed using a solid adsorbent. A small amount of metal components and polymerization inhibitors derived from the catalyst in the reaction product are adsorbed on the solid adsorbent and easily removed by removing this adsorbent.
The acrylate can be purified.

As the solid adsorbent used for the purification, any one or more of activated clay, activated carbon, silica gel and a strongly acidic ion exchange resin are preferable. These may be used alone or in combination of two or more.

The activated clay is obtained by treating naturally occurring acidic clay with sulfuric acid, but may be further treated with acid before use. Activated carbon and silica gel are not particularly limited, and generally commercially available ones may be used. The strongly acidic ion exchange resin is also not particularly limited, and generally commercially available ones can be used.However, the water contained in the resin is replaced by a solvent such as methanol in advance, and then dried by heating under vacuum. It is preferable to remove them.

The contact between the adsorbent and the reactant containing a trace metal and a polymerization inhibitor may be carried out for a certain period of time by a commonly used method such as a fluidized type, a batch type or a fixed bed type. The reaction solution to which the adsorbent has been added may be stirred for more efficient purification.

The contact temperature between the adsorbent and the reactant is not particularly limited, but is preferably from 0 to 100 ° C. If the contact temperature is too high, the (meth) acrylate ester may be polymerized. Usually, the contact time is preferably from 1 to 120 minutes.

The amount of the solid adsorbent used is not particularly limited, but when used in batch purification, it is 0.01 to 100% by mass, preferably 0.1 to 100% by mass, based on the mass of the target (meth) acrylate. It is 1% by mass or more or 10% by mass or less. If too much sorbent is used,
Depending on the type of adsorbent, the target product may also be absorbed and the yield may be reduced. On the other hand, if the amount of the adsorbent used is too small, the treatment effect may be insufficient.

In the present invention, the treatment with the solid adsorbent is preferably performed after removing the catalyst by filtration. That is, after completion of the transesterification reaction, the target product (meth) acrylic acid ester and unreacted (meth) acrylic acid ester and alcohol as raw materials are contained in the reaction solution.
A catalyst and a polymerization inhibitor are included. The purification operation is performed in the following order: (a) filtration of the catalyst, treatment of the adsorbent, unreacted (meth) acrylic acid ester and alcohol of the raw material,
(B) Distillation of unreacted (meth) acrylates and alcohols of raw materials, filtration of catalysts, treatment with adsorbent, (c) filtration of catalysts, distillation of unreacted (meth) acrylates and alcohols of raw materials And adsorbent treatment, but are not limited to these.

[0071]

The present invention will be described below with reference to examples and comparative examples. Methyl methacrylate is abbreviated as MMA.

The components in the reaction solution and the purity of the obtained (meth) acrylate were analyzed by gas chromatography. The content of the N-oxyl compound in the (meth) acrylate was measured by high performance liquid chromatography, and the content of the metal in the (meth) acrylate was measured by ICP emission method.

The definition of the conversion used in the present specification is as follows.

Conversion (%) = (mol number of reacted raw alcohol / mol number of supplied raw alcohol) × 1
00 Yield (%) = (moles of (meth) acrylate obtained / moles of raw material alcohols supplied) × 100 [Example 1] Using a reflux apparatus equipped with a 20-stage Oldershaw distillation column, In a 2L four-necked flask with side tube, MM
A1031 g (10.3 mol), n-butanol 445
g (6 mol), 0.58 g of calcium hydroxide (0.0013 mol per mol of n-butanol), 0.98 g of potassium hydroxide (0.0 mol per mol of n-butanol)
029 mol) and 0.043 g of the N-oxyl compound 8 (described in Table 1), and the mixture was stirred under an air stream to carry out a transesterification reaction for 3 hours. During this time, methanol generated by the reaction was removed from the system by azeotropy with MMA. At this time, the temperature of the reaction solution rose from 102 ° C. to 133 ° C., but no residue or deposit of polymer was found in the kettle or the tower.

Analysis of the reaction solution by gas chromatography revealed that 98.2% of the starting material n-butanol had been converted to n-butyl methacrylate.

Next, the reaction solution was filtered under an air pressure of 150 kPa to separate the catalyst. Then, 8.5 g of activated clay (SA1 manufactured by Nippon Activated Clay Co., Ltd.) was added to the obtained filtrate, and the mixture was stirred at 50 ° C. for 60 minutes. After filtering this treated liquid through a membrane filter (pore size: 0.5 μm), unreacted MMA and butanol were distilled off under reduced pressure to give a purity of 99.
770 g (80.2% yield based on n-butanol) of 8% n-butyl methacrylate was obtained.

When the obtained n-butyl methacrylate was analyzed, both the calcium and potassium metals had the quantification limit.
(30 ppb) or less, and N-oxyl compound 8 is 1 p
pm or less, and the APHA was 5 or less.

[Example 2] Synthesis of n-butyl methacrylate and treatment with activated clay were carried out in the same manner as in Example 1 except that the catalyst filtration residue recovered in Example 1 was used as a catalyst. The reaction temperature was 103 to 131 ° C., and the reaction time was 3.5 hours.

As a result, the conversion based on n-butanol was 9
As a result, 782 g of n-butyl methacrylate having a purity of 99.8% (yield based on n-butanol of 91.6%) was obtained at 6.6%.

When the obtained n-butyl methacrylate was analyzed, both the calcium and potassium metals had the quantification limit.
(30 ppb) or less, and N-oxyl compound 8 is 1 p
pm or less, and the APHA was 5 or less.

Example 3 0.58 g of calcium hydroxide (0.001 to 1 mol of n-butanol) as a catalyst
3 mol) and 0.98 g of sodium hydroxide (0.0041 mol with respect to 1 mol of n-butanol), the synthesis of n-butyl methacrylate and the treatment with activated clay were carried out in the same manner as in Example 1. The reaction temperature was 105 to 133 ° C, and the reaction time was 2.5 hours.

As a result, the conversion based on n-butanol was 9
758 g of n-butyl methacrylate having a purity of 99.9% and a purity of 7.5% (88.8% yield based on n-butanol) were obtained.

When the obtained n-butyl methacrylate was analyzed, both calcium metal and sodium were below the quantification limit (30 ppb), and N-oxyl compound 8 contained 1
At less than ppm, the APHA was less than 5.

Example 4 Synthesis of n-butyl methacrylate and treatment with activated clay were carried out in the same manner as in Example 1 except that the catalyst filtration residue recovered in Example 3 was used as a catalyst. The reaction temperature was 103 to 128 ° C, and the reaction time was 2.5 hours.

As a result, the conversion based on n-butanol was 9
790 g of n-butyl methacrylate (3.25%, yield 92.5% based on n-butanol) having a purity of 99.8% were obtained.

When the obtained n-butyl methacrylate was analyzed, both calcium metal and sodium were below the limit of quantification (30 ppb), and N-oxyl compound 8 contained 1
At less than ppm, the APHA was less than 5.

Comparative Example 1 16.7 parts by mass of calcium hydroxide (0.0 mol per mol of n-butanol) was used as a catalyst.
N-butyl methacrylate was synthesized in the same manner as in Example 1 except that only 376 mol) was used.

As a result, the reaction was carried out for 4 hours, and the conversion based on n-butanol was 91.0%. Thus, when calcium hydroxide alone was used as the catalyst, its activity was low despite the large amount of use.

Comparative Example 2 0.98 g of potassium hydroxide (0.002 to 1 mol of n-butanol) as a catalyst
N-butyl methacrylate was synthesized in the same manner as in Example 1 except that only 9 mol) was used.

As a result, the conversion based on n-butanol reached 74.4% in a reaction time of 2.5 hours, but the reaction did not proceed thereafter, and the conversion based on alcohol was 74.6 even in a reaction time of 5 hours. %Met.

Comparative Example 3 n-Butyl methacrylate was synthesized in the same manner as in Example 1 except that the catalyst filtration residue collected in Comparative Example 2 was used as a catalyst.

As a result, the reaction was carried out for 5 hours, and the conversion rate based on n-butanol was 2.4%. in this way,
It can be seen that when potassium hydroxide alone was used as the catalyst, the activity was lost.

Reference Example 1 Synthesis of n-butyl methacrylate and treatment with activated clay were carried out in the same manner as in Example 1 except that 0.043 g of hydroquinone was used instead of the N-oxyl compound 8 as a polymerization inhibitor. Reaction temperature is 103-131
C. and the reaction time was 3 hours. The conversion based on n-butanol was 96.4%. The obtained n-butyl methacrylate was colored yellow and was APHA100.

From Example 1 and Reference Example 1, it can be seen that the N-oxyl compound is excellent in colorability.

[Example 5] Using the apparatus used in Example 1, 1051 g (10.5 mol) of MMA, 652 g (3.5 mol) of lauryl alcohol, and calcium hydroxide 3
2.6 g (0.12 per mole of lauryl alcohol)
57 mol), 16.3 g of potassium hydroxide (0.0830 mol with respect to 1 mol of lauryl alcohol) and 0.045 g of N-oxyl compound 8 (described in Table 1) were charged into a flask and stirred under a stream of air. For 6.5 hours. During this time, methanol generated by the reaction was removed from the system by azeotropy with MMA. At this time, the temperature of the reaction solution rose from 90 ° C. to 121 ° C., but no residue or deposit of polymer was found in the kettle or the tower.

When the reaction mixture was analyzed by gas chromatography, 99.9% of the raw material lauryl alcohol was converted to lauryl methacrylate.

Next, this reaction solution was filtered under an air pressure of 150 kPa to separate the catalyst. Then, 24 parts by mass of activated clay (SA1 manufactured by Nippon Activated Clay Co., Ltd.) was added to the obtained filtrate, followed by stirring at 50 ° C. for 60 minutes. The treated liquid was filtered through a membrane filter (pore size 0.5 μm) to separate activated clay, and then the filtrate was heated to 80 ° C., and the system was gradually depressurized and finally depressurized to 10 kPa to reduce
Was distilled off. Thus, 814 parts by mass of lauryl methacrylate having a purity of 99.8% (yield based on lauryl alcohol: 91.4%) was obtained.

When the obtained lauryl methacrylate was analyzed, it was found that both calcium and potassium were quantified.
(30 ppb) or less, and N-oxyl compound 8 is 1 p
pm or less, and the APHA was 5 or less.

[Examples 6 to 14] Transesterification was carried out in the same manner as in Example 5 except that the starting alcohols, catalysts and N-oxyl compounds as polymerization inhibitors shown in Table 3 were used. The corresponding methacrylic acid ester was obtained at the reaction temperature, reaction time, and standard conversion rate for alcohols shown in (1).

The methacrylic acid ester obtained was treated with activated clay in the same manner as in Example 5 except that the amount of the activated clay was changed as shown in Table 3. When the obtained methacrylic acid ester was analyzed, the metal components were all below the quantification limit (30 ppb), and the N-oxyl compound was 1
At less than ppm, the APHA was less than 5.

[0101]

[Table 3]

[0102]

According to the present invention, it is possible to produce a high-purity (meth) acrylic ester at a high conversion using an inexpensive solid catalyst which can be easily separated from the product at the end of the reaction. ) It is possible to produce a (meth) acrylate by effectively preventing polymerization of the acrylate.

Continuation of the front page (72) Inventor Motomu Okita 20-1 Miyukicho, Otake-shi, Hiroshima F-term in Central Research Laboratory of Mitsubishi Rayon Co., Ltd. 4H006 AA02 AC48 AD17 BA02 BA06 BA29 BA30 BA32 BA37 BA68 BA72 BA94 KA03 4H039 CA66 CD10 CD90

Claims (4)

[Claims] 1. A method for producing a (meth) acrylate by a transesterification reaction between a (meth) acrylate and an alcohol having 3 to 20 carbon atoms,
As the catalyst, any one or more of calcium oxide, calcium hydroxide, magnesium oxide or magnesium hydroxide, and any one of sodium or potassium hydroxide, halide, carbonate, hydrogen carbonate, carboxylate or alkoxide A method for producing a (meth) acrylic ester, wherein the transesterification reaction is carried out using the above. 2. An N-oxyl compound represented by the following formula (1), an N-oxyl compound represented by the following formula (2) or cyclohexane-1- represented by the following formula (3) as a polymerization inhibitor: Spiro-2 '-(4'-oxoimidazolidin-1'-oxyl) -5'-spiro-
2. The transesterification reaction using one or more 1 ''-cyclohexanes.
The method for producing the (meth) acrylic ester according to the above. Embedded image (In the general formula (1), R ¹ , R ² , R ³ and R ^{4 each} have 1 to 8 carbon atoms.
And may be linear or branched, and R ¹
And R ² , and R ³ and R ⁴ may form a ring with each other. R ⁵
Is H, OH, OR, OCOR, NHCOR or O-
[(EO) _n + (PO) _m ] -H, R ⁶ is H, and R ⁵ and R ⁶ together may be ＯO. EO represents an ethyleneoxy group, PO represents a propyleneoxy group, n and m are the same or different integers from 0 to 10, and n and m are not simultaneously 0.
R is a hydrogen atom or an alkyl group, an alkenyl group or an aryl group having 1 to 18 carbon atoms. The alkyl group may be linear or branched, and the aryl group may be a hydrogen atom substituted with an alkyl group. In the general formula (2), R ²¹ ,
R ²² , R ²³ and R ²⁴ are alkyl groups having 1 to 8 carbon atoms and may be linear or branched, and R ²¹ and R ²² , and R ²³ and R ²⁴ may form a ring with each other. . R ²⁵ is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, an alkenyl group or an aryl group; the alkyl group may be linear or branched; and the aryl group may be a hydrogen atom substituted with an alkyl group. . ) 3. The method according to claim 1, wherein the (meth) acrylate obtained by the transesterification reaction is further subjected to removal of trace metals and a polymerization inhibitor using a solid adsorbent. A method for producing a (meth) acrylic ester. 4. The method according to claim 1, wherein the solid adsorbent is activated clay, activated carbon,
4. The method for producing a (meth) acrylate according to claim 3, wherein the resin is at least one of silica gel and a strongly acidic ion exchange resin.