JP2000072718A - Polymerization inhibitor for (meth) acrylic acid ester comprising (meth) acrylic acid piperidine-1-oxyl ester derivative and method for producing the same - Google Patents

Abstract

(57) [Summary] (Problem corrected) [PROBLEMS] To provide a polymerization inhibitor which exhibits an excellent polymerization inhibitory effect on (meth) acrylic acid esters and does not produce by-products which lower the purity in the system. . SOLUTION: Piperidine-1 methacrylate of the general formula I
-A polymerization inhibitor for methacrylic acid esters comprising an oxyl ester derivative. (R ₁ represents hydrogen or an alkyl group having 1 to 4 carbon atoms.)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a (meth) acrylic acid piperidine-1-oxyl ester derivative useful as a polymerization inhibitor for a (meth) acrylic ester, and a method for producing the same.

[0002]

2. Description of the Related Art Many N-oxyl compounds are known as polymerization inhibitors in the production of (meth) acrylates. JP-B-58-46496 discloses 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-.
Oxyl (hereinafter, this compound is abbreviated as 4HO-TEMPO. In addition, the term "2,2,6,6-tetramethylpiperidine-1-oxyl" is abbreviated as TEMPO.)
4-acetoxy-TEMP, which is an ester derivative of
It is described that O, 4-benzoyloxy-TEMPO and the like are excellent popcorn polymerization inhibitors.

However, when methyl (meth) acrylate is used as a raw material to produce an alkyl (meth) acrylate having a longer chain than a methyl ester by a transesterification reaction,
When these polymerization inhibitors are used, since these polymerization inhibitors are also esters, a part or most of the polymerization inhibitors are transesterified by methyl (meth) acrylate present in a large excess, and the system Undesirable by-products such as methyl acetate and methyl benzoate are mixed into the mixture, which causes a reduction in product purity.

As a method for producing piperidine (meth) acrylic acid 1-oxyl ester derivative represented by the formula (V), for example, 4HO-TEMPO or the like is used.
A method of reacting a -hydroxypiperidine-1-oxyl derivative with (meth) acrylic acid chloride is known (J. poly. Sci. Polymer che).
mystery ed. vol. 10,3295-33
10 (1972)). However, this method requires a reaction in an anhydrous state, and has a problem in handling properties and stability of (meth) acrylic acid chloride as a raw material, and thus cannot be said to be necessarily an industrially advantageous method. Therefore, a method for producing the desired (meth) acrylic acid piperidine 1-oxyl ester derivative represented by the formula (V) with high purity and high yield by using a raw material which is easy to handle and simple operation has been required. .

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and has been made in view of the (meta)
An object of the present invention is to provide a polymerization inhibitor which exhibits an excellent polymerization inhibitory effect on an acrylate ester and which does not generate by-products which lower the purity in the system.

Further, the present invention provides a method for producing a series of piperidine-1-oxyl (meth) acrylate derivatives containing a compound suitable as a polymerization inhibitor in a high yield and a high purity by a simple operation. The aim is to provide a method.

[0007]

DISCLOSURE OF THE INVENTION The polymerization inhibitor for methacrylic esters of the present invention is 4-methacryloyloxy-
2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter abbreviated as 4MA-TEMPO) or the like, and a methacrylic acid piperidine-1-oxyl ester derivative represented by the formula (I) (hereinafter referred to as formula (I)) It is called the compound of I).)
Consists of

[0008]

Embedded image (In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) In addition, the polymerization inhibitor for acrylic acid ester of the present invention is preferably 4
-Acrylic acid piperidine-1-oxyl ester derivative represented by the formula (II) such as -acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter abbreviated as 4A-TEMPO) ( Hereinafter, the formula (I)
I) Compound. ).

[0009]

Embedded image (Wherein, R ₁ has the same meaning as described above.) The present invention also relates to a method for preventing polymerization of methacrylic acid ester using the compound of the formula (I) as a polymerization inhibitor.

[0010] The present invention also relates to a method for preventing the polymerization of an acrylate ester using the compound of the formula (II) as a polymerization inhibitor.

According to the study of the present inventors, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter referred to as 4 (M) A-TEMPO)
Abbreviated. ) Is very effective as a polymerization inhibitor for (meth) acrylic acid esters since a small amount can provide a polymerization inhibitory effect. In particular, when 4MA-TEMPO is used as a polymerization inhibitor at the time of producing a methacrylate by a transesterification reaction, or when 4A-TEMPO is used as a polymerization inhibitor at the time of producing an acrylate by a transesterification reaction, the purity of the product is reduced. Since no by-products are formed, high-purity products are obtained in various reactions.

The present invention further relates to a compound of the formula (III) in the presence of tetramethyl titanate.

[0013]

Embedded image (Wherein R ₁ has the same meaning as described above), and a compound represented by the general formula (IV):

[0014]

Embedded image (Wherein, R ₂ represents a hydrogen atom or a methyl group), and reacted with a methyl (meth) acrylate compound represented by the general formula (V):

[0015]

Embedded image (Wherein R ₁ and R ₂ have the same meanings as described above.) The present invention relates to a method for producing a piperidine-1-oxyl (meth) acrylate derivative represented by the formula:

Further, the present invention relates to a method for preparing a hydroxy compound represented by the above general formula (III) in the presence of tetraethyl titanate,

[0017]

Embedded image (Wherein R ₂ has the same meaning as described above), and is reacted with an ethyl (meth) acrylate compound represented by the formula (V): The present invention relates to a method for producing a 1-oxyl ester derivative.

According to these methods, by a simple operation,
High yield, high purity piperidine (meth) acrylate-1
-Oxyl ester derivatives can be produced.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The compound of formula (I) can be used for various purposes as a polymerization inhibitor of methacrylic acid ester, and the compound of formula (II) can be used as a polymerization inhibitor of acrylate ester. . For example, it is used as a polymerization inhibitor when preserving (meth) acrylate, as a polymerization inhibitor in a reaction using (meth) acrylate as a raw material, and as a polymerization inhibitor in a reaction in which (meth) acrylate is formed. be able to.

Specific examples of the compound of the formula (I) include 4MA-TEMPO, 4-methacryloyloxy-2,3,6-trimethyl-2,6-diethylpiperidine-1-oxyl and 4-methacryloyloxy. −2,6
-Dimethyl-2,6-di-n-propyl-3-ethylpiperidine-1-oxyl, 4-methacryloyloxy-
2,6-dimethyl-2,6-di-n-butyl-3-n-propylpiperidine-1-oxyl and the like can be mentioned.

As the compound of the formula (II), specifically, 4A-TEMPO, 4-acryloyloxy-
2,3,6-trimethyl-2,6-diethylpiperidine-1-oxyl, 4-acryloyloxy-2,6-dimethyl-2,6-di-n-propyl-3-ethylpiperidin-1-oxyl, 4- Acryloyloxy-2,6-
Dimethyl-2,6-di-n-butyl-3-n-propylpiperidine-1-oxyl and the like can be mentioned.

The compounds of the formulas (I) and (II) which are the polymerization inhibitors of the present invention are preferably used alone as polymerization inhibitors, but may be used in combination with other polymerization inhibitors.
The form of the combination is not particularly limited. For example, a form in which the polymerization inhibitor of the present invention and another polymerization inhibitor are added simultaneously, and another polymerization inhibitor is added later to the system in which the polymerization inhibitor of the present invention is present. Examples include a type in which the polymerization inhibitor of the present invention is added later to a system in which another polymerization inhibitor is present. Further, the polymerization inhibitor of the present invention may be used as a piperidine compound such as 2,2,6,6-tetramethylpiperidine or 4HO-T
When a piperidine-1-oxyl compound such as EMPO is produced as a raw material, it may remain in the polymerization inhibitor of the present invention depending on a reaction rate or a purification method. These raw materials are conventionally known as polymerization inhibitors, and can be considered as other polymerization inhibitors.

In particular, 4 (M) A-TEMPO is suitably used as a polymerization inhibitor in the production of (meth) acrylate by transesterification. For example,
(Meth) with low carbon number, such as methyl (meth) acrylate
By using an acrylate and an alcohol or a phenolic OH compound different from the alcohol-derived portion of this ester in a method for producing a (meth) acrylate different from the starting material by a transesterification reaction, high purity is obtained. Can be obtained. In this transesterification reaction, a general catalyst such as a titanium-based catalyst or a tin catalyst can be used. However, the same alkyl group as the alkyl group of the alcohol-derived portion of the raw material (meth) acrylate ester, particularly tetraalkyl titanate, can be used. It is preferable to use a tetraalkyl titanate having a group.

The raw material (meth) acrylate used in the transesterification reaction is preferably methyl (meth) acrylate and ethyl (meth) acrylate. Therefore, the tetraalkyl titanate used in this case is preferably tetramethyl titanate or tetraethyl titanate.

The alcohol or phenolic OH compound used for transesterification is a compound having 3 to 24 carbon atoms, such as n-propanol, isopropanol,
alkanols such as n-butanol, isobutanol, tertiary butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, 2-ethylhexanol, tridecanol, lauryl alcohol, stearyl alcohol; methoxyethanol;
Alkoxyalkanols such as ethoxyethanol and butoxyethanol; alkenoxyalkanols such as allyloxyethanol; alkenols such as allyl alcohol and methallyl alcohol; phenoxyalkanols such as phenoxyethanol; cycloalkanols such as cyclohexanol; Alkylcycloalkanols such as 3,5-trimethylcyclohexanol and 4-tert-butylcyclohexanol; cycloalkylalkanols such as cyclohexylmethanol; phenylalkanols such as benzyl alcohol and phenylethyl alcohol; alkylphenylalkanols;
Haloalkanols such as chloroethanol; cyanoalkanols such as cyanoethanol; aminoalkanols such as dimethylaminoethanol and diethylaminoethanol; phenols such as phenol, 4-tert-butylphenol and 4-cumylphenol; ethylene glycol and diethylene glycol And polyvalent aliphatic alkanols such as trimethylolpropane and pentaerythritol. Among them, alkanols, alkenols, cycloalkanols, and phenylalkanols are preferred.

One example of the production of (meth) acrylate by this transesterification reaction is, for example, when producing i-butyl methacrylate by the reaction of methyl methacrylate with i-butyl alcohol, a catalyst is used. It is preferable to use tetramethyl titanate having the same alkyl group as the methyl group of methyl methacrylate,
As the polymerization inhibitor, 4MA-TEMPO having a common methacrylic acid portion of methyl methacrylate is used. With such a combination, a very pure product can be obtained.

Next, general formulas (I) and (II)
The method for producing the (meth) acrylic acid piperidine-1-oxyl ester derivative represented by the general formula (V) containing

In the general formula (III), R ₁ is
Hydrogen atom, or methyl, ethyl, n-propyl, n-
An alkyl group having 1 to 4 carbon atoms such as butyl, preferably a hydrogen atom.

In the present invention, using such a hydroxy compound and methyl (meth) acrylate represented by the general formula (IV) as raw materials, tetramethyl titanate (Ti
When a transesterification reaction is performed in the presence of (OCH ₃ ) ₄ ), a piperidine-1-oxyl (meth) acrylate derivative represented by the general formula (V) is obtained. R ₁ and R ₂ in formula (V) corresponds to R ₁ and R ₂ of formula (III) and (IV) used as a raw material. Also, instead of methyl (meth) acrylate, (meth)
The same applies when using ethyl acrylate and using tetraethyl titanate instead of tetramethyl titanate.

As the catalyst used in this reaction, tetramethyl titanate is extremely preferred. In place of tetramethyl titanate and tetraethyl titanate, dialkyltin oxide catalysts such as dibutyltin oxide and dioctyltin oxide, which are commonly used for transesterification, cause the catalyst to be mixed into the product, Tetraethyl titanate, tetraisopropyl titanate, tetra-n-titanate
When a titanate compound having an alkyl group having 2 to 12 carbon atoms such as butyl and tetrakis 2-ethylhexyl titanate is used, an ester derived from the catalyst is generated and mixed into the product, so that both have high purity. The compound of the general formula (V) cannot be obtained.

In this reaction, the (meth) compound of the general formula (IV)
It is preferable to use methyl acrylate or ethyl (meth) acrylate of the general formula (VI) in excess with respect to the hydroxy compound of the general formula (III). Furthermore, the reaction can be completed by taking out the produced methanol or ethanol out of the system.

In this reaction, it is generally preferable to remove methanol or ethanol generated by azeotropy with methyl (meth) acrylate or ethyl (meth) acrylate out of the system without using a solvent. As the solvent, for example, hydrocarbons such as benzene, toluene, xylene, hexane, octane, isooctane and cyclohexane can be used. In this case, hexane and cyclohexane are preferable.

[0033] The reaction temperature is 50 ° C to 160 ° C, preferably 80 ° C to 140 ° C. The time required for the reaction can be appropriately selected depending on the reaction time, the type of the catalyst, and the like, and is, for example, 3 hours to 25 hours.

After completion of the reaction, the catalyst is removed by filtration or the like according to a conventional method, and if a solvent is used, the solvent is further distilled off to obtain the compound of the general formula (V)
Can be obtained.

According to this reaction, the desired product can be obtained in a high yield with little generation of by-products. In particular, methyl (meth) acrylate of the general formula (IV) is converted to a compound of the general formula (II)
When the solvent is not used in excess of the hydroxy compound of I), the catalyst may be simply filtered in some cases, so that purification steps such as distillation and recrystallization are not required.
An extremely high-purity (meth) acrylic acid piperidine-1-oxyl ester derivative represented by the general formula (V) can be obtained by a simple operation.

[0036]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.
In addition,% and ppm are all based on weight.

For the following compounds, the following abbreviations are used. 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl: 4HO-TEMPO 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl: 4A-TEMPO 4-methacryloyl Oxy-2,2,6,6-tetramethylpiperidine-1-oxyl: 4MA-TEMPO

[Production example of piperidine-1-oxyl (meth) acrylate derivative] Production examples of piperidine-1-oxyl (meth) acrylate derivative are described in Examples A1 and A2 below and Comparative Examples a1 and a2. Shown in The raw materials, target products, and reaction results used are shown in Table 1.

Example A1 Production of 4MA-TEMPO: 400 g (4 mol) of methyl methacrylate was placed in a 1 L four-necked four-necked flask with a reflux apparatus equipped with a 20-stage Oldershaw distillation column, and 4HO-TEMPO. 172
g (1 mol) and tetramethyl titanate 0.086
g (0.0005 mol) was charged into a flask, and the mixture was stirred under an air stream to perform a transesterification reaction for 6 hours. During this time, methanol generated by the reaction was removed out of the system by azeotropic distillation with methyl methacrylate. At this time, the temperature of the reaction solution was 10
The temperature rose from 5 ° C to 118 ° C.

Next, this reaction solution was distilled under reduced pressure, hexane was added to the obtained crude 4MA-TEMPO crystal, water was added to inactivate tetramethyl titanate, and after filtration, hexane was further added. 4MA-TEMPO having a purity of 99.8% (analysis result by gas chromatography),
236 g were obtained. The crystals were reddish brown crystals having a melting point of 82.5 ° C, and the yield was 98%. No polymer was formed in the tower and the kettle.

Example A2 Production of 4A-TEMPO:
The reaction was performed in the same manner as in Example A1, except that the transesterification reaction was performed for 8 hours using 344 g (4 mol) of methyl acrylate in place of methyl methacrylate. At this time, the temperature of the reaction solution was 95 to 110 ° C.
° C.

Thereafter, a purity of 9 was obtained in the same manner as in Example A1.
9.8% (analysis result by gas chromatograph) of 4A-
TEMPO, 222 g, was obtained. The crystals were reddish brown crystals having a melting point of 103.0 ° C., and the yield was 98%. No polymer was formed in the tower and the kettle.

[Comparative Example a1] Production of 4MA-TEMPO: The procedure of Example A1 was repeated, except that 0.75 g (0.003 mol) of dibutyltin oxide was used instead of tetramethyl titanate. For 9 hours. At this time, the temperature of the reaction solution was 105
C. to 118.degree.

Thereafter, the same treatment as in Example A1 was carried out to obtain a compound having a purity of 99.4% (analysis result by gas chromatography).
233 g of MA-TEMPO were obtained, but dibutyltin oxide could not be removed by filtration.
-3000 pp of dibutyltin oxide in TEMPO
m remained.

[Comparative Example a2] Production of 4A-TEMPO:
In Example A2, instead of tetramethyl titanate,
A transesterification reaction was performed for 10 hours in the same manner as in Example A2 except that 1.02 g (0.003 mol) of tetra-n-butyl titanate was used. At this time, the temperature of the reaction solution was 10
The temperature rose from 5 ° C to 118 ° C.

Thereafter, the same treatment as in Example A2 was performed to obtain 4A having a purity of 99.5% (analysis result by gas chromatography).
-TEMPO, 222 g was obtained, but butyl acrylate derived from the catalyst could not be completely removed.
-1500 ppm of butyl acrylate remained in TEMPO.

[Test Example of Polymerization Prevention Effect] The following Example B1,
B2 and Comparative Examples b1 and b2 illustrate the effect of 4 (M) A-TEMPO obtained in Examples A1 and A2 as a polymerization inhibitor.

Example B1 4M obtained in Example A1
As a result of adding 10 ppm of A-TEMPO to methyl methacrylate and conducting a polymerization test at 120 ° C., no polymerization was performed for 200 hours or more.

[Comparative Example b1] As in Example B1, 10 ppm of hydroquinone was added to methyl methacrylate to give 1
As a result of a polymerization test at 20 ° C., polymerization was performed in 7 hours.

Example B2 4A obtained in Example A2
-Add 10 ppm of TEMPO to methyl acrylate,
As a result of conducting a polymerization test at 90 ° C., no polymerization was performed for 200 hours or more.

[Comparative Example b2] As in Example B2, 10 ppm of hydroquinone was added to methyl acrylate, and
As a result of a polymerization test at ℃, polymerization was carried out in 7 hours.

[Production Example of (Meth) Acrylate by Transesterification] Next, in Examples C1 and C2 and Comparative Examples c1 and c2, as a polymerization inhibitor in the production of (meth) acrylate by transesterification. The result using 4 (M) A-TEMPO is shown. The raw materials, target products, and reaction results used are shown in Table 2.

Example C1 Production of butyl methacrylate: Using a reflux apparatus equipped with a 20-stage Oldershaw distillation column, 400 g (4 mol) of methyl methacrylate, n-butyl were placed in a 1 L four-necked flask with a side tube. 74 g of alcohol
(1 mol), tetramethyl titanate 0.17 g (0.0
01 mol) and 4MA-TEM prepared in Example A1
0.028 g of PO was charged into the flask, and the mixture was stirred under an air stream to perform a transesterification reaction for 4 hours. During this time, methanol generated by the reaction was removed out of the system by azeotropic distillation with methyl methacrylate. At this time, the temperature of the reaction solution rose from 105 ° C to 120 ° C.

Next, this reaction solution was distilled under reduced pressure to give a purity of 9%.
9.8 g of 9.8% (analysis result by gas chromatography) of butyl methacrylate were obtained. The yield was 98%.
No polymer was formed in the tower and the kettle.

Example C2 Production of butyl acrylate:
In Example C1, 344 g (4 mol) of methyl acrylate was used in place of methyl methacrylate.
4A-TEM manufactured in Example A2 in place of TEMPO
The reaction was carried out in the same manner as in Example C1, except that a transesterification reaction was performed for 4 hours using 0.026 g of PO. At this time, the temperature of the reaction solution rose from 100 ° C to 115 ° C.

Next, this reaction solution was distilled under reduced pressure to give a purity of 9%.
126 g of 9.8% butyl acrylate (analysis result by gas chromatography) was obtained. The yield was 98%. No polymer was formed in the tower and the kettle.

Comparative Example c1 Production of butyl methacrylate: In Example C1, 0.75 g (0.003 mol) of dibutyltin oxide was used instead of tetramethyl titanate, and 4A-TEMP was used instead of 4MA-TEMPO.
A transesterification reaction was carried out in the same manner as in Example C1, except that 0.028 g of O was used. At this time, the temperature of the reaction solution rose from 105 ° C to 120 ° C. Next, this reaction solution was distilled under reduced pressure to obtain 139 g of butyl methacrylate having a purity of 99.7% (analysis result by gas chromatography).
The yield was 98%. No formation of a polymer was observed in the column and the kettle, but 100 ppm of butyl acrylate not detected in Example C1 was detected in the product.

[Comparative Example c2] Production of butyl methacrylate: The transesterification was carried out in the same manner as in Example C1, except that 0.028 g of 4-benzoyloxy-TEMPO was used in place of 4MA-TEMPO. went. At this time, the temperature of the reaction solution was 105 ° C to 120 ° C.
Up. Next, this reaction solution was distilled under reduced pressure to obtain 139 g of butyl methacrylate having a purity of 99.7% (analysis result by gas chromatography). The yield is 98%,
No polymer was found in the tower and the kettle, but 90 ppm of methyl benzoate, which was not detected in Example C1, was detected in the product.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

According to the present invention, there is provided a polymerization inhibitor which exhibits an excellent polymerization inhibitory effect on (meth) acrylic acid esters and does not produce by-products which lower the purity in the system. Can be.

Further, according to the present invention, a series of (meth) acrylic acid piperidine-1-oxyl ester derivatives containing a compound suitable as such a polymerization inhibitor can be obtained in a high yield and a high purity by a simple operation. The resulting manufacturing method can be provided.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Junichi Doi 20-1 Miyukicho, Otake City, Hiroshima Prefecture Inside Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Teruo Tani 1600-1 Matsumotocho, Matsuto City, Ishikawa Prefecture Inside the Matsuto Plant, Osaka Organic Chemical Industry Co., Ltd. (72) Inventor Shinji Suzuki 18-8, Katayamacho, Kashiwara City, Osaka Prefecture Inside the Kashiwara Plant, Osaka Organic Chemical Industry Co., Ltd. No. 18-8 Osaka Organic Chemical Industry Co., Ltd. Kashiwara Plant F-term (reference) 4C054 AA02 BB01 BB03 CC07 DD04 DD08 EE01 EE04 EE08 FF26 4H006 AA02 AB46 AD41 4J011 AB01 NA02

Claims (6)

[Claims] 1. A polymerization inhibitor for methacrylic acid esters comprising a piperidine-1-oxyl methacrylate derivative represented by the formula (I). Embedded image (In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) 2. An acrylic acid ester polymerization inhibitor comprising a piperidine-1-oxyl acrylate derivative represented by the formula (II). Embedded image (Wherein, R ₁ has the same meaning as described above.) 3. A method for preventing polymerization of methacrylic acid esters, wherein the piperidine-1-oxyl methacrylate derivative represented by the formula (I) is used as a polymerization inhibitor. 4. A method for preventing the polymerization of acrylate, wherein the piperidine-1-oxyl acrylate derivative represented by the formula (II) is used as a polymerization inhibitor. 5. A compound of the formula (III) in the presence of tetramethyl titanate (Wherein R ₁ has the same meaning as described above) and a hydroxy compound represented by the general formula (IV): (Wherein, R ₂ represents a hydrogen atom or a methyl group), and reacted with a methyl (meth) acrylate compound represented by the following general formula (V): (Wherein R ₁ and R ₂ have the same meanings as described above.) A method for producing piperidine-1-oxyl (meth) acrylate derivative represented by the formula: 6. In the presence of tetraethyl titanate, a hydroxy compound represented by the general formula (III) and a hydroxy compound represented by the general formula (VI): (Wherein R ₂ has the same meaning as described above), and is reacted with an ethyl (meth) acrylate compound represented by the formula (V): A method for producing a 1-oxyl ester derivative.