JP2003321420A - Method for producing (meth)acrylic ester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an objective (meth)acrylic ester in high selectivity by more effectively preventing polymerization of the (meth) acrylic ester in transesterification a (meth)acrylic ester with an alcohol. <P>SOLUTION: The transesterification is carried out by pressurizing a vapor phase part in a reaction vessel by an oxygen-containing gas to dissolve oxygen in a reaction liquid containing the (meth)acrylic ester and the alcohol. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a (meth) acrylic acid ester by a transesterification reaction.

[0002]

2. Description of the Related Art Conventionally, a method for producing a (meth) acrylic acid ester of an alcohol by a transesterification reaction between a (meth) acrylic acid ester and an alcohol has been known and many proposals have been made.

For example, JP-A-57-93930 discloses a method for producing a methacrylic acid ester using an inorganic weak acid salt of alkali metal (carbonate or the like) as a transesterification catalyst. This catalyst has high catalytic activity,
Moreover, it is described in the same publication that there are few side reactions. Further, the same publication describes that the transesterification reaction is carried out under normal pressure or reduced pressure.

JP-A-6-256260 discloses that by-products produced and / or remaining during the production of (meth) acrylic acid ester are recovered by distillation and added to the next reaction (meth) acrylic acid. A method of making an ester is disclosed. It is described in the publication that this can suppress the production of by-products and improve the selectivity of raw materials for products. Further, in the publication, the transesterification reaction is carried out under a reduced pressure of 300 Torr.

Further, in JP-A-3-118352, in a transesterification reaction of a (meth) acrylic acid ester and a dialkylamino alcohol, a saturated hydrocarbon inert to the reaction is added as an azeotropic agent for an alcohol as a by-product. As a pressurized condition (usually, the pressure is 1.5 to 4.0 at).
A method for producing an acrylic monomer for carrying out the reaction in m) is disclosed. This greatly reduces the reaction time,
It is described in the same publication that effects such that side reactions rarely occur and the loss of the raw material (meth) acrylic acid ester is reduced. Further, the publication describes that when the reaction is not carried out under pressure, the reaction time is long and the reaction yield is poor.

However, the conventional method is not always sufficient in the effect of preventing the polymerization of the (meth) acrylic acid ester, and a method of more effectively preventing the polymerization to produce the (meth) acrylic acid ester with a high selectivity is desired. It is rare.

Further, in the method using the azeotropic agent described in JP-A-3-118352, the raw material cost becomes high,
In consideration of recycling of raw materials, there is also a problem that equipment cost is increased because separation from the azeotropic agent is required.

[0008]

DISCLOSURE OF THE INVENTION The present invention aims to prevent polymerization of a (meth) acrylic acid ester more effectively in a transesterification reaction between a (meth) acrylic acid ester and an alcohol and to achieve a high selectivity. An object of the present invention is to provide a method for producing (meth) acrylic acid ester.

[0009]

The above object can be achieved by the present invention described below. A method for producing a (meth) acrylic acid ester of an alcohol by a transesterification reaction between a (meth) acrylic acid ester and an alcohol, the reaction comprising a (meth) acrylic acid ester and an alcohol in a reactor. There is a liquid phase part which is a liquid and a gas phase part, and the gas phase part is pressurized with an oxygen-containing gas to dissolve oxygen in the reaction liquid, and the transesterification reaction is performed (meta). ) A method for producing an acrylic ester. The method for producing the (meth) acrylic acid ester, wherein the oxygen-containing gas contains 20% by volume or more of oxygen. The method for producing a (meth) acrylic acid ester as described above, wherein the gauge pressure in the gas phase in the reactor is 0.005 to 0.5 MPa during the transesterification reaction.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a gas phase portion in a reactor is pressurized with an oxygen-containing gas, and a transesterification reaction is carried out in a state where oxygen is dissolved in a reaction liquid containing (meth) acrylic acid ester and alcohol. I do. By sufficiently dissolving oxygen in the reaction solution, a high effect of preventing polymerization of the (meth) acrylic acid ester can be obtained, and as a result, the desired (meth) acrylic acid ester can be produced with high selectivity. The dissolved oxygen concentration in the reaction solution at the start of the transesterification reaction is preferably 100 mass ppm or more from the viewpoint that the polymerization of the (meth) acrylic acid ester can be more effectively prevented.

Further, by carrying out the transesterification reaction in a state where the gas phase portion in the reactor is pressurized with the oxygen-containing gas, the amount of dissolved oxygen in the reaction solution can be kept high, and the risk of polymerization is low. It becomes possible to adopt a higher reaction temperature in the state. As a result, the reaction rate is improved and the reaction can be performed more efficiently. During the transesterification reaction, the gauge pressure in the gas phase in the reactor is preferably 0.005 MPa or more.

The dissolved oxygen concentration in the reaction solution at atmospheric pressure is about several tens of ppm with respect to the total mass of the reaction solution at a solution temperature of about 100 ° C., although it varies depending on the combination of the raw materials. The dissolved oxygen concentration in the reaction solution under reduced pressure becomes even lower. At such a dissolved oxygen concentration, a sufficient polymerization preventing effect cannot be obtained. In order to obtain a high polymerization inhibiting effect, it is necessary to pressurize the reaction solution to sufficiently dissolve oxygen therein.

The term "(meth) acrylic acid ester" as used herein means "acrylic acid ester" and "methacrylic acid ester" as commonly used. Further, the gauge pressure is a pressure display that represents the atmospheric pressure as 0 (reference).

The present invention will be described in detail below.

The (meth) acrylic acid ester as the reaction raw material is not particularly limited as long as it undergoes a transesterification reaction with the raw material alcohol, and for example, methyl (meth) acrylate, ethyl (meth) acrylate and the like can be used. it can.

The raw material alcohol is not particularly limited and may be appropriately determined depending on the intended (meth) acrylic acid ester. As the raw material alcohol, specifically, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, n-pentanol,
Alkanols such as n-hexanol, n-heptanol, n-octanol, 2-ethylhexanol, tridecanol, lauryl alcohol and stearyl alcohol; alkoxyalkanols such as methoxyethanol, ethoxyethanol, butoxyethanol; alkeno such as allyloxyethanol. Xylalkanols; Alkenols such as allyl alcohol and methallyl alcohol; Phenoxyalkanols such as phenoxyethanol; Cycloalkanols such as cyclohexanol;
3,3,5-trimethylcyclohexanol, 4-te
alkylcycloalkanols such as rt-butylcyclohexanol; cycloalkylalkanols such as cyclohexylmethanol; phenylalkanols such as benzyl alcohol and phenylethyl alcohol; alkylphenylalkanols; haloalkanols such as chloroethanol; cyanoethanol and the like Cyanoalkanols; aminoalkanols such as dimethylaminoethanol and diethylaminoethanol; phenol, 4-
Phenols such as tert-butylphenol and 4-cumylphenol may be mentioned. Above all, higher effects of the present invention can be obtained when the reaction is carried out using alkanols, alkenols, cycloalkanols, and phenylalkanols.

The carbon number of the raw material alcohol is preferably 24 or less. When the carbon number is 25 or more, the reaction rate becomes very slow and the reaction may not proceed in some cases. Further, the (meth) acrylic acid ester produced has a high boiling point, and it tends to be difficult to distill it.

The amount of the (meth) acrylic acid ester as a raw material used (mixing ratio for charging) may be appropriately determined, but is preferably 1 mol or more, and more preferably 1.2 mol or more per 1 mol of the raw material alcohol. The amount of the (meth) acrylic acid ester used as a raw material (mixing ratio for charging) is preferably 5 mol or less, and more preferably 4 mol or less, relative to 1 mol of the raw material alcohol.

In the present invention, when carrying out the transesterification reaction,
It is preferable to add a polymerization inhibitor to the reaction solution.

The polymerization inhibitor used in the present invention is not particularly limited, and any known one can be used. Examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, catechol, phenothiazine, N, N-di-2-naphthyl-p-phenylenediamine, nitric acid and nitrates. 1 polymerization inhibitor
One kind may be used, or two or more kinds may be used in combination.

The amount of the polymerization inhibitor used may be appropriately determined, but from the viewpoint of polymerization inhibition, it is preferably 0.001% or more with respect to the mass of the raw material (meth) acrylic acid ester, and 0.0
05% or more is more preferable. The amount of the polymerization inhibitor used is preferably 1% or less, more preferably 0.5% or less, with respect to the mass of the raw material (meth) acrylic acid ester from the viewpoint of separation during purification.

In order to substantially start the transesterification reaction, both reaction raw materials and the catalyst are brought into contact with each other. Specifically, a polymerization inhibitor is added to a reaction liquid containing (meth) acrylic acid ester as a reaction raw material and an alcohol, and a gas phase portion in the reactor is pressurized with an oxygen-containing gas to dissolve a desired amount of oxygen. After that, the catalyst is added as it is or after being dissolved or suspended in a suitable solvent to the reaction solution to substantially start the transesterification reaction. As a solvent for dissolving or suspending the catalyst, a reaction raw material (meth) acrylic acid ester or alcohol may be used.

The catalyst used in the present invention is not particularly limited, and any known catalyst can be used. Examples of the catalyst include sodium carbonate, basic ion exchange resins, alkali catalysts such as calcium oxide and magnesium oxide, tin catalysts such as di-n-butyltin oxide and di-n-octyltin oxide, and tetra-n-butoxy. Titanium,
Examples thereof include titanium catalysts such as tetra-n-methoxytitanium, solid catalysts such as calcium oxide containing metallic titanium, and the like. The catalyst may be used alone or in combination of two or more.

The amount of the catalyst used may be appropriately determined, but is preferably 0.0001 mol or more, more preferably 0.0004 mol or more, relative to 1 mol of the raw material alcohol. Further, the amount of the catalyst used is preferably 0.5 mol or less, more preferably 0.1 mol or less, relative to 1 mol of the raw material alcohol.

In the present invention, in order to improve the effect of preventing polymerization, the gas phase portion in the reactor is pressurized with an oxygen-containing gas to dissolve oxygen in the reaction solution to carry out a transesterification reaction. At this time, the reaction liquid or the reaction liquid and the gas phase portion of the reactor may be stirred.

The oxygen-containing gas to be used is not particularly limited as long as it preferably contains oxygen in an amount of 20 to 100% by volume, but when considering the cost of raw materials and equipment,
It is preferable to use air.

The dissolved oxygen concentration in the reaction solution at the start of the reaction is
From the point of obtaining a higher polymerization inhibiting effect, 100 mass p
pm or more is preferable. Excessive pressurization for increasing the dissolved oxygen concentration causes high cost of the reactor and peripheral equipment.

During the reaction, the pressure of the gas phase in the reactor may be appropriately determined depending on the combination of the raw materials, the reaction temperature, etc. so that the desired dissolved oxygen concentration in the reaction solution can be obtained. The gauge pressure of the gas phase in the reactor during the reaction is preferably 0.005 MPa or more, and more preferably 0.01 MPa or more, from the viewpoint of obtaining a higher polymerization inhibiting effect. In addition, the gauge pressure of the gas phase in the reactor during the reaction is preferably 0.5 MPa or less from the viewpoint of the cost of the reaction device and peripheral equipment,
0.4 MPa or less is more preferable.

When the gas phase in the reactor is pressurized with air, the gauge pressure is 0.0 if the temperature of the reaction solution is 80 ° C.
The dissolved oxygen concentration in the reaction solution was adjusted to 1 by applying a pressure of 4 MPa or more, or by applying a gauge pressure of 0.25 MPa or more when the temperature of the reaction solution was 140 ° C.
It can be set to 00 ppm or more.

The reaction temperature may be appropriately determined according to the combination of raw materials, but from the viewpoint of reaction rate, it is preferably 60 ° C. or higher, more preferably 80 ° C. or higher. The reaction temperature is
From the viewpoint of preventing the polymerization of (meth) acrylic acid ester, 15
It is preferably 0 ° C or lower, more preferably 140 ° C or lower.

The reaction time may be appropriately determined, but usually,
It can be about 0.5 to 20 hours.

Since the transesterification reaction of the (meth) acrylic acid ester is an equilibrium reaction, it is preferable to carry out the reaction while removing the product out of the system in order to proceed the reaction.

The reactor used in the present invention is
There is no particular limitation as long as the inside of the reactor can be pressurized, and examples thereof include a stirring tank type batch type and continuous type apparatus, and a stirring tank type batch type and continuous type apparatus having a distillation apparatus. Above all, a stirred tank type apparatus having a distillation apparatus is preferable because the product can be removed by distillation. The distillation conditions may be appropriately determined.

After the transesterification reaction is carried out in this way to produce a (meth) acrylic acid ester, the (meth) acrylic acid ester produced is usually purified by a known method such as distillation.

[0035]

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

The analysis (measurement of the contents of raw materials and products in the reaction solution) in the examples was carried out by gas chromatography. The selectivity was defined as the ratio of the number of moles of the target product (butyl methacrylate) produced to the number of moles of the raw material alcohol (n-butanol) consumed by the reaction. The formation of the polymer was visually confirmed.

[Example 1] Methyl methacrylate (496 g, 4.9 g) was placed in a 1 L autoclave in a glass container equipped with a stirring blade, a thermometer, a catalyst inlet and a gas inlet to the gas phase.
5 mol), 220 g (2.97 mol) of n-butanol,
0.254 g of hydroquinone was charged. Then, the reaction solution was heated to 120 ° C. with stirring, and air was supplied to pressurize the inside of the glass container to a gauge pressure of 0.2 MPa to dissolve oxygen in the reaction solution.

Reaction liquid temperature 120 ° C., gauge pressure 0.2 M
0.257 g of tetramethyl titanate dissolved in 10 g (0.10 mol) of methyl methacrylate at Pa
(1.49 mmol) was forced into the liquid phase portion in the reactor by air. Then, the reaction was carried out for 3 hours while maintaining the reaction liquid temperature at 120 ° C. and the gauge pressure at 0.2 MPa. During the reaction, the internal reaction liquid was taken out at regular intervals and analyzed. The results are shown in Table 1.

Comparative Example 1 A 1 L autoclave similar to that used in Example 1 was charged with 496 g of methyl methacrylate, 220 g of n-butanol and 0.254 g of hydroquinone.
Then, the reaction solution was degassed for 20 minutes while being stirred, and then the gas phase part was pressurized with nitrogen to a gauge pressure of 0.2 MPa, and the reaction solution was heated to 120 ° C.

Reaction liquid temperature 120 ° C., gauge pressure 0.2 M
In Pa, 0.257 g of tetramethyl titanate dissolved in 10 g of methyl methacrylate was pressed into the liquid phase part in the reactor with nitrogen. Then, in the same manner as in Example 1, the reaction was performed for 3 hours. The results are shown in Table 1. After the reaction, a minute polymer was confirmed in the reactor.

Example 2 A 1 L autoclave similar to that of Example 1 was charged with 492 g (4.91 mol) of methyl methacrylate, 218 g (2.94 mol) of n-butanol, and 0.253 g of hydroquinone. Then, the reaction solution was heated to 130 ° C. with stirring, and air was supplied to pressurize the inside of the glass container to a gauge pressure of 0.3 MPa to dissolve oxygen in the reaction solution.

Reaction liquid temperature 130 ° C., gauge pressure 0.3M
0.253 g of tetramethyl titanate dissolved in 10 g (0.10 mol) of methyl methacrylate at Pa
(1.47 mmol) was forced into the liquid phase portion in the reactor by air. Then, in the same manner as in Example 1, the reaction was performed for 3 hours. The results are shown in Table 1.

[Comparative Example 2] A 1 L autoclave similar to that used in Example 1 was charged with 492 g of methyl methacrylate, 218 g of n-butanol and 0.253 g of hydroquinone.
Then, the reaction solution was degassed for 20 minutes while being stirred, and then the gas phase part was pressurized with nitrogen to a gauge pressure of 0.3 MPa, and the reaction solution was heated to 130 ° C.

Reaction liquid temperature 130 ° C., gauge pressure 0.3M
In Pa, 0.253 g of tetramethyl titanate dissolved in 10 g of methyl methacrylate was pressed into the liquid phase part in the reactor with nitrogen. Then, in the same manner as in Example 1, the reaction was performed for 3 hours. The results are shown in Table 1. After the reaction, a minute polymer was confirmed in the reactor.

[0045]

[Table 1]

In Examples 1 and 2 in which the gas phase in the reactor was pressurized with air to dissolve oxygen in the reaction solution and the transesterification reaction was performed, compared with Comparative Examples in which the reaction was performed in a nitrogen atmosphere. The formation of the polymer was suppressed, and the selectivity of the target product, butyl methacrylate, was high.

[0047]

INDUSTRIAL APPLICABILITY According to the present invention, in the transesterification reaction between a (meth) acrylic acid ester and an alcohol, the polymerization of the (meth) acrylic acid ester can be prevented more effectively, and the object is to achieve a high selectivity ( (Meth) acrylic acid esters can be produced.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Ogawa             20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Rayo             Otake Office F-term (reference) 4H006 AA02 AC48 BA02 BA06 BA10                       BA11 BA30 BA32 BA72 BB60                       BC11 BC13 BC14 KA03                 4H039 CA66 CD10 CD40 CD90

Claims (3)

[Claims] 1. A method for producing a (meth) acrylic acid ester of an alcohol by a transesterification reaction between a (meth) acrylic acid ester and an alcohol, the method comprising: There is a liquid phase part, which is a reaction liquid containing alcohol, and a gas phase part. The gas phase part is pressurized with an oxygen-containing gas to dissolve oxygen in the reaction liquid, and the transesterification reaction is performed. A method for producing a (meth) acrylic acid ester having a feature. 2. The method for producing a (meth) acrylic acid ester according to claim 1, wherein the oxygen-containing gas contains oxygen in an amount of 20% by volume or more. 3. The method for producing a (meth) acrylic acid ester according to claim 1, wherein the gauge pressure in the gas phase in the reactor is 0.005 to 0.5 MPa during the transesterification reaction.